1994 Annual Summary Report on Rsults NEDO-WE-NET-94

International Clean Energy Network Using Hydrogen Conversion

(WE-NET)

March, 1995

New Energy and Industrial Technology Development Organization

020005192-8

NEDO

Preface

Because of the exhaustion of fossil fuel and uncertainty for global environment, Japanese government has been taking an active part in development of new energy for the past 20 years.

In 1992,Agency of Industrial Science and Technology in the Ministry of Inter­national Trade and Industry (MITI) presented the project entitled International Clean Energy Network Using Hydrogen Conversion(WE-NET:World Energy Net­work), as a part of the New Sunshine Project.

The WENET project aims at efficient utilization of energy with its focus on renewable energy that is unevenly distributed in the world. This project will include hydrogen production from water by harnessing renewable energy,transportation of hydrogen by converting to the form suitable for transportation,and supply to large energy consuming areas.

This project term is divided into three phases extending over a 28-year period,from 1993 to 2020. The target of this project is the establishment of not only hardware technologies such as hydrogen energy but of software technologies that will realize its introduction throughout the world.

The world wide diffusion of the WE-NET project will contribute to the reduc­tion of carbon dioxide,alleviation of international energy supply and demand,and creating opportunities for more energy production and for fostering export indus­tries in countries blessed with renewable energy.

Efforts have to be made to find out solutions for environmental problems in­cluding global warning and energy crisis that will both become world scale seri­ous problems in the 21st century. It is an important theme to develop WE NET project into an international cooperative research program on a global scale. We hope that this project will contribute to the leading of broad and active discussion on policies and R&D of clean energy.

March,1995

New Energy and Industrial Technology Development Organization

List of participants in International Clean Energy Network Using Hydrogen Conversion(WE-NET)

development Committee>

Chairman: Dr.Kazuo FuekiMember : Ph.D.Seijiro Ihara

Professor emeritus,University of TokyoProfessor

Department of Systems Engineering, Nippon Institute of Technology

Dr.Kazuo Takeya Former Professor,Faculty of Engineering,University of Tokushima

Yoshiko Nakahara Director,Department of Energy & the Environment, Osaka National Research Institute,AIST

Dr.Kenzo Fukuda Project ManagerWE NET Center,

Dr. Kazuo KontaniThe Institute of Applied EnergyDirector General,Energy Engineering Department, Mechanical Engineering Laboratory

Mr.Hiroyuki Kobayashi Director, General Manager Planning Department

Mr.Hiroyasu OnishiJapan Ethanol Co.Ltd.Manager,Engineering Development Department,The Central Electric Power Council

(Tasks entrusted to>

The Institute of Applied EnergyEngineering Advancement Association of JapanThe Japan Research and Development Center for MetalsCentral Research Institute of Electric Power IndustryJapan Power Engineering and Inspection CorporationElectric Power Development Co. Ltd.L ondon Research Centre Imperial College Consultants Ltd.

Agency of Industrial Science and Technology (AIST)

Review and Investigation for Promoting International Cooperation

Conceptual Design of the Total System

Conceptual Design of the Total System

Study on a Global Network

—National-level Energy Estimation and Assessment

—City-level Energy Estimation and Assessment

Development of Hydrogen Production Technologies

—Safety Measures and Evaluation Technologies

Development Committee

New Energy and Industrial Technology Development Organization (NEDO)

Investigation and Study for Evaluating and Reviewing R&D

Development of Hydrogen Transportation and Storage Technology

. Development of Large-capacity Hydrogen Liquefaction Facility

-Development of Liquid Hydrogen T ransportation T anker

— Development of Liquefied Hydrogen Storage Facility

— Development of Devices for Common Use

— Development of Hydrogen Absorbing Alloysfor Small Scale Transportation and Storage System

Development of Cryogenic Materials Technology

Feasibility Study on Utilization of Hydrogen Energy

Study for an Optimum System for Hydrogen Combustion Turbine

— Development of the Combustion Control Technology'

—Development of Turbine-blade, Rotor and Other Major Components

— Development of Major Auxiliary Equipment

—Development of Super-pyrogenic Materials

Study of Innovative and Leading T echnologies

Development of Hydrogen Combustion Turbine

Implementing Structure of WE NET Project

Table of Contents

I .Summary

1. Items and targets of R&D ...................................................................................... i2. Summary of FY 1994 results ................................................................................ v3. Development toward tomorrow ............................................................................ ix

11.1994 Annual Summary of Results under Each Individual Subtask

1. Subtask 1: Investigation and study for evaluating and reviewing R&D ............ 12. Subtask 2: Review and investigation for promoting international cooperation * * 33. Subtask 3: Conceptual design of the total system .................................................. 8

3.1 Conceptual designs of the total system ............................................................ 83.2 Study on a global network ..............................................................................193.3 National-level energy estimation and assessment ........................................ 253.4 City-level energy estimation and assessment ................................................ 303.5 Safety measures and assessment ....................................................................38

4. Subtask 4: Development of hydrogen production technologies .......................... 405. Subtsak 5: Development of hydrogen transportation and storage technology • • 52

5.1 Development of large-capacity hydrogen liquefaction facilities ................... 525.2 Development of the liquid hydrogen transportation tanker ......................... 595.3 Development of the liquid hydrogen storage facility ..................................... 695.4 Development of devices for common use ......................................................... 775.5 Development of hydrogen absorbing alloys for small scale transportation

and storage system ...........................................................................................826. Subtask 6: Development of cryogenic materials technology .............................. 877. Subtask 7: Feasibility study on utilization of hydrogen energy ...................... 948. Subtask 8: Development of a hydrogen-combustion turbine ............................ 101

8.1 Study for an optimum system for hydrogen-combustion turbine ............... 1018.2 Development of combustion control technology ........................................... 1068.3 Development of turbine blades, rotors and other major components • • • • 1138.4 Development of major auxiliary equipment ................................................. 1158.5 Development of super-pyrogenic materials ................................................. 117

9. Subtask 9: Study of innovative, and leading technologies .............................. 120

I. Summary

I .Summary

International Clean Energy Network Using Hydrogen Conversion (WE-NET) aims at establishment of technologies for constructing the world wide hydrogen energy network. This system will include hydrogen production from water by make use of electrolysis utilizing reproduceable energies such as hydraulic, solar, geothermal, wind and so on, conversion into transportable medium, transporta­tion to energy consumption areas and utilization for consumption.

1. Items and target of R & DR&D for Phase I is divided into the following 9 subtasks.

1.1 Subtask 1 investigation and study for evaluating andreviewing R&D

Terget of this subtask:• Coordinating all of the individual subtasks related to hydrogen production, transportation, storage and utilization (including hydrogen combustion tur­bine), and overall evaluation of the results

• Formulation of optimum development porgrams• Investigation and study of advances in domestic and foreign technologies re­

lated to WE-NET project, and reflection of these advancements upon future programs

1.2 Subtask 2 : Review and investigation for promotinginternational cooperation

Target of this subtask:• Information exchange with countries or organizations involved in similar

projects• Review and investigation of the method, framework and policy for developing

WE NET project into an international cooperative research program whose ob­jective is establishing a world scale system

1.3 Subtask 3 : Conceptual design of the total systemTarget of this subtask:

• Development of a conceptual design enocompassing the total system, including such facilities as for electric generation using renewable energy, hydrogen pro­duction, production of transportation medium, storage, transportation, and uti­lization, and technological and economical evaluation

- Estimation of the effect of the introduction of hydrogen energy on long-term

i

Pig. 1 Schematically Illustrates WE-NET,

energy supply and demand, both from a global viewpoint and from the view­point of each country

• Development of safety measures and evaluation technologies viewed at the total WE-NET system

1.4 Subtask 4 : Development of hydrogen production technologiesSolid Polymer Electrolyte Water Electrolysis has been selected as the electroly­

sis medthod for WE-NET project.Target of this subtask:

• Research required for increasing the scale of Solid Polymer Electrolyte Water Electrolysis and the elongation of membrane life

• Development of elemental technology concerning Solid Polymer Electrolyte (Ion exchange membrane), anode and cathode catalysts, materials of cell parts, and so on, and the bench scale test of them

• Establishment of technology required for pilot plant construction

1.5 Subtask 5 : Development of hydrogen transportation andstorage technology

Although there is very little experience in handling liquid hydrogen as a me­dium for transportation both in Japan and abroad, liquid hydrogen offers the advantages of being easily transportable in large amounts, being easily converted thus requires simple technology, and being convenient in case of utilization in consuming areas. Therefore, the development stage for Phase I will chiefly re­search the handling of liquid hydrogen.

Other possible forms of hydrogen transportation will be dealt with in Subtask 3 (Conceptual design of the total system) in consideration of R&D progress and practicality of liquid hydrogen.

Target of this subtask:- Basic study and development of the elemental technology required for hydrogen

liquefaction, transportation, storage, and so on• To obtain information required for long-distance marine transportation and

small scale transportation and storage• Development of elemental technology in some fields concerning large-capacity

hydrogen liquefaction facility and various devices for common useA) Development of large-capacity hydrogen liquefaction facilityB) Development of liquid hydrogen transportation tankerC) Development of liquid hydrogen storage facilityD) Development of devices for common use (large-capacity liquid hydrogen

pumps, adiabatic piping, valves)

in

E) Development of hydrogen-absorbing alloys for small-scale transportation and storage system

1.6 Sub task 6 : Development of cryogenic materials technologyTarget of this subtask:

• To obtain fundamental knowledge about toughness, fatigue and serration caused by liquid hydrogen behavior at low temperature

• Establishment of a method to evaluate cryogenic material proper for hydrogen embrittlement in order to judge whether new cryogenic materials development is necessary

• Investigation and evaluation of welding techniques and materials usable in the state of liquid hydrogen

• Presentation of desires from the materials’ point of view regarding Develop­ment of Hydrogen Transportation and Storage Technology (SubtaskS)

1.7 Subtask 7 : Feasibility study on utilization of hydrogen energyTarget of this subtask:

• Investigation of technologies using hydrogen and estimation of the consumption of hydrogen in different fields, such as electric power, transportation,other in­dustry or civil use

• Investigation of different methods of using hydrogen gas, liquid hydrogen, methanol, and so on to clarify the merits and demerits of implementing each technology

• Extracting developmental themes of hydrogen utilization• Investigation and evaluation of technology using liquefied hydrogen cryogenic

energy

1.8 Subtask 8 : Development of hydrogen-combustion turbineTarget of this subtask:

• Investigation and research of elementary technologies for a hydrogen combus­tion turbine that is expected to perform dramatically higy efficiency

• Establishment of basic technologies needed to construct a pilot plant• The R&D is planned as follows:

A) Study for an optimum system for hydrogen-combustion turbineB) Development of the combustion control technologyC) Development of turbine blade, rotor and other major componentsD) Development of major auxiliary equipmentE) Development of super-pyrogenic materials

IV

1.9 Subtask 9 : Study of innovative and leading techologiesWE-NET is a superlongterm project that aims at world-wide diffusion in the

year around 2030. That means there may be some certain innovative and pio­neering technologies not included in its R&D objects though promising for the future will make much progress. On the other hand, incorporation of existing technologies in WE-NET project may be necessary depending upon the trend of technological improvements.

Such being the case, targets of this subtask are:- Research and evaluation of innovative, pioneering, and existing technologies • Research of elementary technology, and reflection of promising technologies

upon WE-NET project

Schedule of R&D for Phase I is shown in Table-1

2. Summary of FY 1994 results.In FY 1994, research on the existing technologies was the center of R&D activi­

ties in each developmental field, but a study on elementary technologies was also commenced in some fields. Major results obtained will be summarized below;

2.1 Subtask 1 : Investigation and study for evaluating andreviewing R&D

Investigation of a pilot plant of Phase II was commenced.

2.2 Subtask 2 : Review and investigation for promotinginternational cooperation

a. International symposium was held to promote exchanges of technologies and information; and

b. Investigations were made on the formation of global network and long-term vi­sion.

2.3 Subtask 3 : Conceptual design of the total systema. The conceptual design of total system was made with liquid hydrogen as the

target to estimate facility cost and economy on a trial basis.b. In order to evaluate the effects obtained by introducing the hydrogen energy on

the bases of world scale, nation-scale and municipal scale, improvement and co­ordination of the existing simulation model were commenced.

c. Selection on accident cases to occur and investigation of analytical codes were started for safety evaluation.

v

2.4 Subtask 4 : Investigation and development of hydrogenproduction technologies

Based on three different technologies of electrode bonding methods, chemical plating, hot press method and porous electrocatalyst method, a small capacity laboratory cell evaluation facility with a capacity of 50 cm3 was made to carry out performance evaluation. Also, developments on hydrogen production by zero- gap method and on high temperature and strength solid electrolyte were com­menced.

2.5 Sub task 5 : Development of hydrogen transportation andstorage technology

a. Development of large-capacity hydrogen liquefaction facilityProcess investigations were carried out roughly on the helium Brayton cycle

and hydrogen Claude cycle as the liquefaction cycle.b. Development of liquid hydrogen transportation tanker

Basic specifications were determined and a conceptual design was made on a tanker carrying square-shaped tanks with the same capacity as that carrying sphere-shaped tanks each with a capacity of 200,000 m3, the external appear­ances of which are shown in Figs. 2 and 3.c. Development of liquid hydrogen storage facility

Basic system flow was investigated and specifications of facility unit of storage site were determined roughly.d. Development of devices for common use (large capacity hydrogen pumps, adia­

batic piping, valves)A survey was continuously carried out on large-capacity liquid hydrogen

pump, heat insulation piping, liquid hydrogen valve and measurement units to extract technical themes.e. Development of hydrogen absorbing alloys for small-scale transportation and

storage systemInvestigations were made on magnesium alloys small in weight but large in

hydrogen storage capacity as well as on the improvement effect of characteristics by nano-crystallization.

2.6 Subtask 6 : Development of cryogenic materials technologyOut of typical existing structural materials, stainless steels, SUS304L and

SUS316L and aluminum alloy, A5084, were selected and tested on mechanical properties at the helium temperature level as well as on the hydrogen embrittlement to collect data for them.

vi

R & D item 1993 1994 1995 1996

1. Investigation and study for evaluating and reviewing R & D < ■>

2. Review and investigation for promoting international cooperation <■

3. Conceptual design of the total system

(1) Conceptual design of the total system

(2) Study on global network

(3) National-level energy estimation and assessment

(4) City-level energy estimation and assessment

(5) Safety measures and assessment

4. Development of hydrogen production technologies <r ■>

5. Development of hydrogen transportation and storage technology

(1) Development of large-capacity hydrogen liquefaction facility

(2) Development of liquid hydrogen tanker

(3) Development of liquid hydrogen storage facility

(4) Development of devices for common use

(5) Development of hydrogen-absorbing alloys for a small-scale

transportation and storage system

<r

6. Development of cryogenic materials technology <■

7. Feasibility study on utilization of hydrogen energy < >

8. Development of hydrogen-combustion turbine

(1) Study for an optimum hydrogen-combustion turbine system

(2) Development of combustion control technology

(3) Development of trubine blades, rotor and other major

components

(4) Development of major auxiliary equipment

(5) Development of super-pyrogenic materials

9. Study of innovative and leading technologies <

Table-1 Schedule of R&D for WE-NET, Phase I

Fig.2 Liquid hydrogen transportation tanker (sphere-shaped)

Fig.3 Liquid hydrogen transportation tanker (square-shaped)

Vlll

2.7 Subtask 7 : Feasibility study on utilization of hydrogen energyField investigation were carried out on various hydrogen utilization technolo­

gies to extract technical problems and analyzed them.

2.8 Sub task 8 : Development of hydrogen-combustion turbinea. Study for an optimum system for hydrogen-combustion turbine

Several types of system of hydrogen-combustion turbine were investigated and an electric power generation efficiency of 60% was confirmed to be attained as shown in Table 2.b. Development of combustion control technology

A small-scale burner was made for achieving the basic test of hydrogen-oxygen combustion burner and flame stability and combustibility were evaluated.c. Development of turbine blade, rotor and other major components

Though evaluated based on the calculation, even when both moving and station­ary blades were made of existing metallic materials, it was confirmed that they could be withstood the turbine inlet temperature of 1700 °C by improving the cooling technology of blades.d. Development of major auxiliary equipment

Research and investigation were made on the heat-transfer promotion technol­ogy of high temperature heat exchanger as well as on its type, structure and materials to be used and so on. Oxygen production system utilizing the cryogen­ics of liquid hydrogen was also researched and investigated.e. Development of super-pyrogenic materials

Heat-resistant alloy, intermetallic compound, ceramic-system composite and C/ C composite which are promised as materials for making ultra-high temperature components such as blade of hydrogen combustion turbine were tested and evalu­ated to make clear their basic characteristics (physical, chemical and mechanical properties).

2.9. Subtask 9 : Study of innovative and leading technologiesIn order to find innovative and leading technologies, research and investigation

were carried out and at the same time, the evaluation procedures of these tech­nologies were considered.

3. Development toward tomorrowResearch, basic investigation and study of elementary technologies and other

investigations will be carried out continuously to FY 1994 to obtain necessary information for the optimum design of the total system and make sure of establish­ment of technologies required to design and construct a pilot plant.

IX

Table 2 Outline and efficiencies of various types of hydrogen-combustion turbine proposed

Cycle Two-stage reheat/regenerative Ran- kine cycle

Inert gas circulating cycle Topping extraction cycle Bottoming reheat cycle Two-stage reheat Rankine cycle

Systemstructure

H2 Oz HzOz » *

Hz Oz Hz Oz Hz OzH U H

----- ©j^---

Outline Rankine cycle is the base.

Water vapor is the working medium.

Efficiency is improved by reheat and so on.Compressor is not needed.

Combined cycle is the base.

Topping cycle has water vapor and inert gas as the working medium, and bottoming cycle has water vapor as the working medium.

System structure is the same as the normal gas turbine and steam turbine combined cycle.

Combined cycle is the base.

Both topping and bottoming cycles have water vapor as the working medium.

This cycle features that topping and bottoming cycles have the same work­ing medium.

Combined cycle is the base.

Both topping and bottoming cycles have water vapor as the working medium.

This cycle features that topping and bottoming cycles have the same work­ing medium.

Rankine cycle is the base.

Water vapor is the working medium.

Efficiency is improved by reheat and so on. Compressor is not needed.

Efficiency (See note)

60%(1700%, 75bar)

55%(1700%, 50bar)

62%(1700%, 50bar)

62%(1700%, 50bar)

62%(1700%, lOObar)

Notes i Efficiency is in terms of HHV (Higher Heating Value) at the generating end. Values in parentheses show highest temperatures and pressures at the inlet.

II. 1994 Annual Summary of Results under Each Individual Subtask

II. 1994 Annual Summary of Results under Each Individual Subtask

1. Subtask 1 : Investigation and study for evaluating andreviewing R&D

Phase I of the WE-NET project covers surveys and studies for overall evalua­tion and development plans involved in the project. The aim of the first phase is to work out a draft plan for Phase II of the project, including the assessment of research and development results in Phase I and the construction of pilot plants. The research plan for fiscal 1994, which ended March 1995, called for an analy­sis of the current state of research and development activities on elemental tech­nologies for the WE-NET system, total coordination of the whole project, intersegmental assessment of development results and a study on the research and development program in Phase I with an outlook on plans for the following years.

In order to achieve these objectives, a special committee, consisting of subtask committee chairmen, experts from various sectors concerned and researchers di­rectly involved in development activities, was set up to examine research plans and achievements of individual subtask groups for elemental technologies as well as for the total WE-NET system. In addition, a leading researchers panel, consist­ing of the heads of subtask research units, to find the current state of research and development activities and to coordinate inter-subtask affairs.

Researches for fiscal 1994 were conducted under these plans and arrange­ments for facilitating their implementation. Studies by the committee found that the plans for carrying out the subtasks are appropriate and well-fitted for attain­ing the objectives of the whole Phase I program. The research efforts in fiscal 1994 were rated high in that desired results were being achieved steadily accord­ing to the plans and that the first draft image of the WE-NET system, in particu­lar, was worked out in the form of energy and system flows. These results have made it easier to objectively find the positioning of each subtask in the whole system.

However, the committee holds the view that too much importance should not be attached to the current estimates relating to economical evaluation of the WE- NET (e.g., the power generating cost of hybrogen combustion turbine) because the evaluation was made on the basis of diverse assumptions and inferences.

Mean while, the leading researchers panel discussed and adjusted inter-subtask boundary problems of which major topics covered as many as 13 items.

Based on the results of these research and development efforts, an attempt was

1

made to review the whole Phase I program and work out a draft research plan for fiscal 1995. The review led to the recognition that the Phase I program should remain basically the same as originally drafted and that surveys and studies for overall evaluation and development plans involved in the WE-NET project should be continued to permit the assessment of Phase I achievements in fiscal 1996.

2

2. Subtask 2 : Review and investigation for promotinginternational cooperation

This research is intended to clarify how to collaborate with relevant countries and to exchange technical information internationally for the purpose of develop­ing this project into a real international joint one, in the International Clean En­ergy Network Using Hydrogen Conversion (WE-NET) Project.

In FY1993, the tasks that will be required for promoting international coopera­tion in WE-NET were extracted and sorted by studying similar projects.

In FY1994, research, examination and measures were carried out on the fol­lowing items based on the examination from the previous fiscal year as the devel­opment stage for realizing international cooperation in the WE-NET project.

1. Measures for obtaining international understanding and cooperation for WE- NET

2. Measures for promoting international exchange of technical information.

3. Measures for forming international network

4. Examination for formulation of long-term vision for international cooperation

5. Identification of Hydrogen Opportunities in Canada and Alaska

6. Review and Forecast of Hydrogen Activities in Canada The summary is illustrated in the following.

2.1 Measures for obtaining international understanding and cooperation for WE-NET

Being a project based on the premise of international cooperation, it is impor­tant that the concept of WE-NET is understood extensively and accurately among the agencies and parties abroad for it to obtain their cooperation. Accord­ingly, drafting and implementation of measures that are needed to promote the basic approach of WE-NET abroad was taken up as the priority task for this fiscal year, resulting in implementation of the following.

(1) Preparation and distribution of English materials for thorough understanding of WE-NET Project by allAn English introductory leaflet and a synopsis of Report on the Results from

3

FY1993 were prepared by NEDO and distributed among the participants at the International Hydrogen and Clean Energy Symposium (IHCE ’95) held in Tokyo in February 1995 and among pertinent parties overseas.

(2) Presentation at international conferencesInternational conferences and symposiums that are held around the world pro­

vide effective opportunities for introducing the concept and plans of WE-NET to overseas. For this reason, international conferences related to hydrogen technol­ogy that are scheduled in the near future were studied and the method of presen­tation was examined. Under the determination that an ideal timing of announce­ment would be the 11th World Hydrogen Energy Conference which will be held on June 1996 in Germany, a target has been set on this conference and the ap­proach for respective sub-tasks was made.

(3) Holding of international symposiumIn holding the International Hydrogen and Clean Energy Symposium (IHCE ’95)

sponsored by NEDO, a full-scale back up of the operation was carried out as a part of international cooperation activities under the WE-NET subtask 2. As many as 50 participants from 11 countries joined from overseas, among 434 attendants. In addition to the lectures for introducing overall planning of WE- NET and the content of technical development, introduction of the actual contents of research and development in respective subtasks made a great contribution to further understanding of the present situation of WE-NET. In addition, signifi­cant results in building the foundation for future cooperation were obtained through exchange of information during the symposium and subsequent technical exchange sessions.

2.2 Measures for promoting international exchange of technical information

In developing WE-NET into an international joint research project under inter­national cooperation, it will be essential to implement exchange of information and discussion with pertinent organizations on a regular basis while maintaining close cooperation with the countries involved. As the basis for drafting measures to promote international exchange of technical information, an ideal method of technical information exchange and a possible scenario for its implementation were reviewed through studies of present situation at oversea research organiza­tions of hydrogen-related technologies, studies of present situation of technical information exchanges at various occasions including IEA(International Energy Agency)’s meetings and hydrogen-related international conferences.

4

In the study of research organizations at respective countries, a total of 3disor­ganizations and companies that are implementing hydrogen related technology were listed on a field and region basis.

As for the present situation regarding exchange of technical information, tech­nical exchange sessions were held and opinions were exchanged with related sub­tasks this fiscal year with Canadian Liquid Air, Daimler-Benz Aerospace and Airbus and Stanford University. In addition, 9 overseas study missions were sent from respective subtasks and information was exchanged with each party involved. Meanwhile, at IEA, multilateral cooperation is under way at the Hydro­gen Executive Committee as well as at three workshops for photoproduction of hydrogen, integrated systems and metal hydrides for hydrogen storage, under the leadership of New Sunshine Project Promotion Headquarters, Agency of Indus­trial Science & Technology, MITI.

Furthermore, for the world wide activities in the major hydrogn related confer­ences held in this fiscal year, the status of presentations such as at the 10th world Hydrogen Energy conference, held in Florida, June, 1994, and at the 6th Ameri­can Hydrogen conference held in Virginia, March, 1995 was outlined.

2.3 Measures for forming international networkAs mentioned in the previous chapter, WENET is a project that is materialized

under international understanding and cooperation. Therefore, for efficient pro­motion of WE NET, it is essential to establish a system for promoting develop­ment under participation and cooperation with various overseas organizations. As preceding step for this, it will be important to form international networks on various levels that can examine the direction of the project and on how to share of responsibilities.

For this reason, the problems and tasks were extracted by studying policies and status of development at countries that are actively pursuing hydrogen energy,such as United States, Canada and Germany. These studies were made based on the papers that were presented at the 10th World Hydrogen Energy Conference, while analyzing opinions on WE NET from overseas, thereby examin­ing the measures for forming an international network.

As an example of this measure, an idea is proposed to creat something like a WE-NET International Forum. It’s details , however, will have to be examined further along with the preparation of the long-term vision of the project.

2.4 Examination for preparation of long-term vision for international cooperation

In order to develop WE NET into a joint international project by meeting the

5

requirements mentioned above, a development of strategic measures based on a long term vision will be required.

The initial works for making long-term vision include:

(1) Clarification of project philosophy that offers common awareness of the prob­lems and to indicate the purpose that can be endorsed among the countries involved .

(2) Clarification of merit that can be obtained through participation and coopera­tion in the project by the countries involved.

(3) Clarification of development scenario that secures conformity with energy and environmental policies of the countries involved and at the same time offers synergetic effect through cooperation.

Moreover, materialization of international cooperation requires, for instance,in terms of cooperation in frontier technology, the symmetrical access of researchers, substantiation of funds and protection of intellectual rights; in terms of cooperation with developing countries, support system, it’s form and contents. The future task would be to identify these tasks further and examine the measures for each task by considering the timing of its implementation, and then, to prepare them for long term vision.

2.5 Identification of Hydrogen Opportunities in Canada and AlaskaTo assist in consideration of energy transport from overseas in the form of

liquid hydrogen which is assumed in WE-NET, scenarios, including economic analysis, for exporting liquid hydrogen from British Columbia (B.C.) and Alaska to Japan was studied by the Hydrogen Industry Council of Canada(HIC). Costs of liquid hydrogen delivered to Japan include its production, liquefaction, electricity transmission of 1,000km, ocean transport, storage and shipping facilities as well as 10% contingency for losses during loading and transfer of liquid hydrogen and were estimated as follows.

B.C. Alaska1GW Scenario CA$ 4.05/kg CA $ 5.50/kg4GW Scenario CA$ 3.74/kg CA $ 5.18/kg

End results indicated that costs were mainly dependant on hydroelectricity costs, set at 3c/ kWh for B.C and 5c/kWh for Alaska.

In selecting the lowest cost scenario of B.C, an investment of CA $ 3,785M for 1GW scenario and CA $ 11.253M for the 4GW scenario would be required.

6

2.6. Review and Forecast of Hydrogen Activities in CanadaTo complement the study on hydrogen energy development program in various

countries of the world, hydrogen activities in Canada were reviewed by HIC.The Canadian strategy for hydrogen development can be defined according to

the three elements listed below.

(1) Development based on natural energy resources

(2) A focus on developing world leading hydrogen technologies

(3) Promotion of international partnership for the world supply of clean energy The principal Canadian R&D programs are discussed and projects and activi­

ties are identified as part of hydrogen development in Canada, such as the Alberta Hydrogen Research Program and the Euro-Quebec Hydro-Hydrogen Pilot Project. A special section of the report is dedicated to Canadian firms active in the hydro­gen sector, presenting their project involvements and technological assets.

7

3. Subtask 3 : Conceptual design of the total system

3.1 Conceptual design of the total systemThe objective of the conceptual design of the total system is to describe the

design configuration of a system ranging from the hydrogen production to its utilization by conducting a concept design on a practical scale and at the same time to present a technological development target from the viewpoint of economic efficiency by making cost estimate and analysis of hydrogen, etc.In the fiscal 1993, which was the first year for this research, an investigation

was conducted on the present situation of each individual technology of the pro­cesses from the hydrogen production to its utilization as well as on the present situation of the similar projects overseas. Based on this investigation, eligible technologies were selected which were applicable to the WE-NET system, and thus a system was established, on the basis of which a concept design would be executed from the fiscal 1994 onward. Based on these results, in the fiscal 1994, in order to evaluate as a whole system the technology currently under research and development in WE NET, concept design, cost estimate and analysis of the whole system have been conducted and a technological development target has been presented based on the economic evaluation. This system comprises the hy­drogen production by means of solid polymer water electrolysis, large scale trans­portation and storage of hydrogen in the form of liquid hydrogen, and a hydrogen combustion turbine power generation. In addition, the computer software has been developed to enable efficient execution of concept design,cost estimate and analysis.

The present development situation has been investigated and its concept has been studied regarding the large scale transportation of liquid hydrogen by air.

3.1.1 Conceptual design(1) Basic conditions

In order to make a conceptual design, it is necessary to specify the scale of a hydroelectric power plant and the distance of transportation between supply area and consumption area, and for cost estimation it is necessary to determine the generation cost. However, these figures will be used only as parameters because it is difficult to specify them due to existence of a large number of supply areas of hydroelectric power resources and consumption areas of hydrogen.

The scale of a hydroelectric power plant is set to 1,000 MW -4,000 MW, con­sidering the scale of required power in the consumption area, and the distance of transportation is set to 5,000 km - 20,000 km, considering the estimated distance between supply area and consumption area. The generation cost is set to 2 - 5

8

yen/kWh, considering a hydroelectric power generation cost in Asia.

(2) Conceptual designConceptual design has been conducted based on the set up design conditions

and study cases. System flow diagram of the total system is shown in Figure 3-1- 1.

The design conditions have been set up based on the data such as the capacity of the facilities constituting the base of the design, the number of systems, electric power consumption rate, etc. obtained from the companies conducting element technology research on this system in WE-NET. As for the method of power sup­ply to each facility, it is assumed that in a supply area power will be supplied from a hydroelectric power plant and in a consumption area it will be supplied from a hydrogen-combustion gas turbine power plant. Also, the gasified hydrogen generated during transfer, storage and transportation of liquid hydrogen will be re liquefied at a loading point, supplied to a hydrogen-combustion gas turbine power plant at an unloading point and used as navigational fuel during transpor­tation.

The conceptual design was conducted on two cases. One was the basic case through a combination of the scale of power supply and the distance of transpor­tation. The other was a variation case to evaluate an impact of a change in the basic specifications of the facilities on energy efficiency and costs. As for the facility specifications in the basic case, the water electrolysis efficiency was set to its final target value of 90 % (hydrogen production unit requirements.94 kWh/Nm3), the navigation speed of a tanker to 25 kn which is the upper limit value of the present research and development target value, and the boil off rate during transportation to 0.2 %/day. On the other hand, in the variation case, the water electrolysis efficiency was set to 80 % which is the lower limit value of the interim target value (hydrogen production unit requirement: 4.43 kWh/Nm3), the navigation speed of a tanker to 20 kn which is the lower limit value under study as a development target, and the boil off rate during transportation to 0.4 %/day.

The results showed that in the basic case the system efficiency was about 70 % at the receiving point of hydrogen and about 37 % at the sending end of a hydro­gen-combustion gas turbine power plant as shown in Table 311. The breakdown of energy loss is as follows: About 28 % in the hydrogen production and liquefac­tion processes (about 20 % in the hydrogen liquefaction process and about 8 % in the hydrogen production process) and about 32 % in the hydrogen-combustion gas turbine power generation process. It was thought that a fairly high system effi­ciency was obtained in this study as most of gasified hydrogen generated inside the system was recovered. System efficiency is slightly different depending on the

9

cases, which is mainly attributable to the differences in gasification losses during transportation.

Table 3-1-1 : Energy balance (Basic case) (Unit: %)

Case Case 1 Case 2 Case 3 Case 4 Case 5 Case 6

ConditionsPower scale (MW) 1,000 1,000 1 ,000 4,000 4,000 4,000Transportation distance (km) 5,000 10,000 20,000 5,000 10,000 20,000

Hydroelectric power energy 100.0 100.0 100.0 100.0 100.0 100.0

LossesHydrogen production losses 7.9 7.9 7.9 7.9 7.9 7.9Hydrogen liquefaction losses 19.8 19.8 20.0 19.8 19.8 19.8Transportation losses 0.7 1 .4 2.8 0.7 1 .4 2.8Other losses 1.2 1 .2 1 .2 1 .2 1.2 1 .2

Hydrogen energy 70.4 69.7 68.1 70.4 69.7 68.1

Hydrogen power generation energy

37.7 37.2 36.5 37.7 37.3 36.6

Note: Percentage of hydrogen energy is calculated on the basis of the volume of hydrogen received. Percentage of hydrogen power generation energy is calculated on the basis of the power generating at sending end.

In the variation case the impact was the largest when the electric power con­sumption rate of hydrogen production facilities was altered as shown in Table 3 1-2. In this case, the hydrogen production losses were almost twice, and the sys­tem efficiency dropped to 34.3 %. This fact indicates that the amount of produced hydrogen decreased due to an increase in the electric power consumption rate (decrease in energy efficiency) because the supplied power was constant.

A decrease in system efficiency was minimal because the impact of changes in the navigation speed of a tanker and boil off rate during transportation were insignificant.

10

Loading SiteG02

A

Oxygen Gas Cooler

(1 1

IndustrialWater

WaterPurifier

I

I

OxygenSideGas Liquid Separator

Hydrogen Gas Cooler

CirculationCooler

APressure Vessel

Power Reception : 4.000MWTransport Distance : 10,000km

CirculationPump

soCirculationHeater

DC Power

Annual Power Reception : 31.22X10®kWhHydrogen Production Plant

Capacity : 32,490Nm3 /hX25 units

Flow: 73.0(61.4) t/h Pressure : 1 kg/cm 2g Temperature : RT

Vent/Flare Stack Capacity: 14.3 t/h

Flare Stack Capacity : 11.6 t/h

BDG Compressor

Return Gas Blower

Capacity : 19.7 t/h Pressure : 0.2kg/cm^g Temperature : 0.2~

A

HydrogenSideGas Liquid Separator

Flow : 2.7(14.3) t/h Pressure : 8kg/cm2 g Temperature : RT

Capacity : 14 .3 t/h Discharge pressure : 8kg/cm2 g Temperature : RT

Material Hydrogen Compressor

HydrogenPurifier

Recycle Hydrogen Compressor

KhKH

Flow : 19.7 t/h Pressure : 0.2kg/cm 2 g Temperature : 20k~

Exhaust Gas Dissipation

NitrogenProductionPlant

Capacity: 33,400Nm 3/h

StorageTank

GN2 Cold Box

NitrogenLiquefier

Flow : 2.8 t/h Pressure : 0.05kg/cm2 g Temperature : 20k~

Expansion Turbine

Flow : 8.1 t/h Pressure : 0.2kg/cm2g Temperature: 20k~

LN2 StorageTank

Capacity: 334,000Nm3/h

Hydrogen Liquefactin PlantCapacity : 2601/dX7 units

Flow: 75.7 t/h Pressure : 1 kg/cm2 g Temperature : 20.6k

Nigrogen Liquefier Flow : 9,240Nm3 /h-N2

Flow: 583. Pressure:

. Delivery PumpOx T I Flow : 583.5 t/hStorage Tank Pressure :1 kg/cm

Capacity : 42,000m2 X 5 units Temperature : 20.4kPressure: 0.05kg/cm 2gTemperature: 20.4kBOR : 0.1 %/dAcceptance flush: 1%

5 t/h2kg/cm g

TunkerCapacity: 165,000m3

Pressure : 0.05kg/cm2g Temperature: 20.4K BOR : 0.2%/d Acceptance flash : 1.3% (Holding vessels : 3 vessels)

Figure 3-1-1 WE-NET System Flow11 ~ 12

Table 3-1-2 : Energy Balance (Variation Case)Scale of hydroelectric power generation: 4,000 MW,

Transportation distance: 5,000 km (Unit:%)

Case Basic Case? Case8 Case9

ConditionsHydrogen production unit requirement (kWh/Nm3-H2) 3.94 4.43 3.94 3.94Tanker navigation speed (kn) 25 25 20 25Tanker boil off rate during transportation (%/day) 0.2 0.2 0.2 0.4

Hydroelectric Power Generation Energy 100.0 100.0 100.0 100.0

LossesHydrogen production losses 7.9 16.2 7.9 7.9Hydrogen liquefaction losses 19.8 18.0 19.8 19.8Gastification losses during transportation 0.7 0.6 0.9 1.4Other losses 1.2 1.1 1.2 1.2

Hydogen Energy 70.4 64.1 70.3 69.7

Hydrogen power generation energy 37.7 34.3 37.6 37.3

Note ! Percentage of hydrogen energy is calculated on the basis of the volume of hydrogen received. Percentage of hydrogen power generation energy is calculated on the basis of the power generating at sending end.

(3) Cost estimateThe costs of facilities used in each process from hydrogen production, liquefac­

tion, storage, transportation to its utilization through hydrogen-combustion gas turbine power generation as well as hydrogen and power generation were esti­mated in each case based on the hydroelectric power plant scale, hydroelectric power generation cost, and distance of transportation. The basic data such as costs of facilities, scale factor, annual running cost, etc. were obtained by request from the companies conducting the element technology research on this system in WE NET. Cost of power generation was estimated constant throughout the plant’s life. Costs of land acquisition and construction of berth were not included because it is quite difficult to estimate them due to a great fluctuation.

Table 3 1-3 and Figure 3-1-2 shows the cost estimate in the basic case.

13

Table 3-1-3: Cost Estimate(Basic case, Hydroelectric power generation cost: 2 yen/

kWh)

Case Casel Case2 Case3 Case4 Case5 Case6

Power scale (MW) 1,000 1,000 1,000 4,000 4,000 4,000Tranportation distance (km) 5,000 10,000 20,000 5,000 10,000 20,000

Total facility cost (108yen) 4,607 4,940 5,461 14,624 15,275 16,387

Hydrogen cost (yen/Nm3) 11.38 12.95 15.62 10.08 10.84 12.15

(yen/Mcal) 11.38 12.95 15.62 10.08 10.84 12.15

Power generation cost (Yen/kWh) 37.04 39.67 43.97 30.12 31.36 33.52

Note: Hydrogen cost is calculated on the basis of the volume of hydrogen received. Power generation cost is calculated on the basis of the power generating at send­ing end.

As shown in Table 3 1-3, the cost of hydrogen is about 10 to 16 yen/Mcal which is almost 10 times more than the current GIF price of LNG. The power generation cost in the case of a hydroelectric power plant with the capacity of 4,000 MW is about 30 to 34yen/kWh, while in the case of a hydroelectric power plant with the capacity of 1,000 MW is about 37 to 44 yen. This shows that the cost is lower as the plant scale becomes greater from the viewpoint of scale merit. This power generation cost is about 3 to 4 times more than the current power generation cost using LNG.

In order to study the impact of the facility specifications such as hydrogen production unit requirement on the power generation cost, cost estimate was con­ducted for the variation case as shown in Table 314.

14

50

PowerGenerationCost(Yen/kWh)

40

30

20

10

0

□ Hydroelectric Power Generation Hydrogen Production

Hill Hydrogen Liquefaction 0 Hydrogen Storage(Loading point) §| Hydrogen Tanker§§ Hydrogen Storage(Landing point) g Hydrogen Combustion Turbin

43.97

39.6737.04

Distance 5,000km 10,000km 20,000km 5,000km 10,000km 20,000km

Power Scale 1 , 0 0 0 M W 4 , 0 0 0 M W

Figure 3-1-2. Cost Estimate(Basic Case. Hydroelectroc power ganeration cost: 2 yen/kWh)

15

Table 3-1-4: Cost Estimation (Variation Case)Scale of hydroelectric power generation: 4,000 MW, Hydroelectric power generation cost:2 yen/kWh,

Transportation distance: 5,000 km

Case Basic Case? CaseS Case9

Hydrogen production unit requirement (kWh/Nm3-H2) 3.94 4.43 3.94 3.94Tanker navigation speed (kn) 25 25 20 25

Tanker boil off rate during transportation (%/day) 0.2 0.2 0.2 0.4

Power generation cost (yen/kWh) 30.12 30.62 30.57 30.36

Note: Power generation cost is calculated on the basis of the power generating at sending end.

As shown in Tabled-1-4, in the case where the hydrogen production unit re­quirement was changed from 3.94 kWh/Nm3 to 4.43 kWh/Nm3 and the navigation speed of a tanker from 25 kn to 20 kn, the power generation cost increased by about 0.5 yen/kWh, and in the case where the boil off rate during transportation by tanker was changed from 0.2 %/day to 0.4 %/day, the cost increased by ap­proximately 0.3yen/kWh. However, this cost estimate was made on the assump­tion that the basic facility cost was constant although the facility capacity of water electrolysis and tanker was changed. Therefore, an increase in these costs will become smaller if the facility cost can be cut down by downgrading the facil­ity specifications.In the basic case, the storage capacity of the storage facilities (at a unloading site) were originally set to 30 days of hydrogen consumption, which was considered to be the minimum capacity of the existing thermal electric power plant

However, since the storage cost forms a large proportion of the power genera­tion cost, cost estimate was also made in the case where the storage capacity was changed. The result showed that the storage cost for 10 days was equivalent to 2 yen/kWh in terms of the power generation cost.

16

3.1.2 System design softwareIn order to efficiently conduct the concept design, cost estimate, and analysis of

the whole system, the software to calculate the energy flow, system configuration, costs, etc. has been developed by using the hydroelectric power generation scale, transportation distance, and hydroelectric power generation unit cost as param­eters.

In this fiscal year a computer program was generated to apply it to the system composed of facilities for producing and liquefying hydrogen and for storing liq­uid hydrogen, a tanker for transporting liquid hydrogen, and hydrogen-combus­tion gas turbine power generating facilities, and this program was utilized in making the concept design and calculating the costs.

The functions and features of this program are as follows;

(1) Inputting calculating conditionIt is designed so that an estimate case, parameter varying range, design condi­

tion, and cost estimate condition are set by one operation from the input table. Therefore, the conditions, etc. can be easily changed.

(2) Calculation processingAs for the calculation processing which is the core of the program, the energy

flow, system configuration, facility costs, other costs, etc. are calculated by one operation based on the input calculation condition to automatically make lists and graphs.

(3) User interfaceA user can perform a series of processing ranging from condition input to cal­

culation processing, result display, and printing by operating the program accord­ing to a processing selection menu displayed on the screen.

3.1.3 Concept of transporting liquid hydrogen by airA Canadian company was requested to conduct an investigation and study on

the concept of large scale transportation of liquid hydrogen by air. The summary is given below.

(1) Present situation of developmentIt is indispensable for the air transport of liquid hydrogen to develop a large

aircraft. At present the airports are in an extreme state of congestion with air­planes taking off and landing. Therefore the aircraft manufacturing companies have been vigorously trying to develop a very large aircraft. It is thought that a

17

single fuselage aircraft which can house a cylindrical liquid hydrogen tank is suitable to transport liquid hydrogen. The company is studying the basic concept on the large scale transportation of liquid hydrogen in cooperation with its asso­ciates.

(2) Concept of air transport of liquid hydrogenGerman and Russian aerospace firms are jointly making a liquid hydrogen air

transport plan in which the top of the airframe is extended to place a liquid hydrogen tank. Since liquid hydrogen is lower in temperature than LNG, heat leak control of liquid hydrogen is more difficult, but it is thought that a boil off rate of 0.2 %/day or less can be achieved by employing a multi-layered super insulation. Assuming that the loading capacity is 3,000 m3 and an aircraft transports liquid hydrogen 10 times/day, transportation of 30,000 m3/day, that is 900,000 m3/ month, is possible. Design requirements for aircraft development and liquid hy­drogen producing and receiving facilities have also bee studied and a comparison with marine transportation of liquid hydrogen has been made.

3.1.4 Future themes of studyIn fiscal 1994 the conceptual design was carried out based on the development

target data submitted by the enterprises and institutions conducting the research and development in order to evaluate the technology researched and developed in WE NET as the whole system. However, as it has not been long since the research and development was started and the element technology development is now being conducted, the data will be reviewed according to the progress in the re­search and development.

In fiscal 1995 a conceptual design on the system mainly composed of existing technologies will be carried out, and a comparison and evaluation will be made between the liquid hydrogen transportation and storage system developed in fis­cal 1994 and the present system.

In fiscal 1996 a conceptual design on the system mainly composed of innova­tive technologies will be conducted and an overall comparison and evaluation will be made on the basis of the outcome of the concept design carried out so far.

18

3.2 Study on a gloval network

’’Global Network Studies” will cover renewable resource volume data survey and the simulation analysis using a global energy model. The goals of the WE- NET Phase I (1993^1996) studies will;

(1) survey renewable energy resources such as hydro-power and solar energy to confirm the feasibility of the WE-NET project from viewpoint of the resource volume converting to hydrogen.

(2) develop a energy model to analyze condition for introduction of hydrogen energy, amount of that and effects by modification of a existing global energy model.

(3) conduct simulation analysis of condition for introduction of hydrogen energy, amount of that and effects for various cases, by the data obtained on survey of renewable energy resources into the modified energy model.

To this end, where survey of renewable energy resources converting to hydro­gen is concerned, a study carried over from fiscal 1993 was continually con­ducted as to hydro power and solar energy. As to the modification of a global energy model, a study was conducted on the structure of the OECD GREEN model in preparation for modification. At the same time, a modification design and modi­fication work were conducted to suit to the analysis of the WE-NET.

3.2.1 Survey of renewable energy resources converting to hydrogen

In fiscal 1993, survey of renewable energy resources converting to hydrogen was conducted for hydro power and solar energy. As a result of the survey, as to hydro power, it has been found out that the unexplored hydro power resource volume is roughly equals to today’s aggregate generated energy throughout the entire world, and hydro-power resources can sufficiently serve as resources to hydrogen in the early stages of practical WE-NET operation. As for solar energy, assuming that photovoltaic power generation system is used as hydrogen-produc­tion resources in desert areas and it’s conversion efficient rate is about 15%, the energy resource volume of the world major desert regions amount to approxi­mately 70 times as much as today’s worldwide demand for energy, meaning that solar energy is abundantly available as future hydrogen-production resources.

19

During fiscal 1994, a study carried over from fiscal 1993 was conducted con­cerning hydro power and solar energy. As to hydropower energy, a reappraisal was conducted of the world’s potential hydro power resources, that were deter­mined by research conducted in fiscal 1993, based on the latest materials. In parallel with this, region-by-region potential hydro power resources were esti­mated in accordance with the GREEN model’s zoning pattern. Furthermore, to obtain a measure of generating costs in future hydrogen production, data has been collected about generating cost for hydro power generation projects,in the plan­ning stage and the construction stage alike, in the Asian region. Based on the data, a study was conducted regarding the relationship among power station out­put, the amount of annual power generation, and generating cost. As a result, the following have been found out:

(1) Even among medium-scale 100-to-300-MW plants,some feature lower generat­ing costs. However, many of them concentrate on and in the vicinity of US$0.06/kWh.

(2) Where large-scale power stations rated at 1,000 MW and upward are con­cerned, many of them feature less than US$0.04/kWh in generating cost. There are quite a few stations capable of operating at even less than US$0.02/ kWh.

(3) As for the highest generating costs at individual generating output levels, there is a right-leaning relationship all the way up to 4,000 MW.As for solar energy, data concerning long term cost prospects for photovoltaic

power generation and so forth was collected, in order to study data that becomes necessary to be input into the GREEN model when simulation analyses will be performed from fiscal year 1996 onward.

3.2.2 Study of the GREEN model structureIn preparation for modification of the GREEN model, the model’s individual

functions as well as it’s portions to be modified were identified. In particular, a detailed study was conducted of production and energy structures.

As a result of this, for the addition of the ability to analyze hydrogen energy use, it has been decided that modeling efforts shall be made based upon the exist­ing model’s back stop idea.

Furthermore, current version of GREEN spans the period 1985-2050, the model solves for eight years within this time range of 65 years. Initially, the model has an inter-year gap of five years, after 2010, the inter-year gap is 20

20

years.Considering that the use of hydrogen energy is scheduled to begin after the year

2020 under the WE-NET project, the year 2020 was inserted to divide the inter­year gap into 10 years.

3.2.3 Modification of GREEN modelDesign and modification work was carried out for the GREEN model: the incor­

poration of the ability to analyze the hydrogen energy and the addition of new calculation years. In particular,as for the former concerned with the incorpora­tion of the hydrogen-analysis ability, a study was conducted to draw up a modifi­cation design which would make it possible to perform analyses by taking full advantage of the current model’s features while at the same time taking into ac­count the properties of hydrogen to be supplied under the WE-NET project.

(1) Concept of hydrogen supplyIn the case of analyses to be performed using the GREEN model, untapped

hydro power generation and photovoltaic power generation in desert zones are assumed to be major sources of energy to produce hydrogen.

Since hydro power produced hydrogen (hydro power hydrogen) and solar power-produced hydrogen (solar power hydrogen) differ from each other in the following points in terms of the available amounts of resources and cost, provi­sions shall be made when writing software programs in order that analyses may be performed on them independently of each other.

a. Hydro power hydrogen(D Since supply sources of hydrogen in large quantities mean excessive supplies

of hydro power, hydrogen supplier countries (regions) are limited to countries (regions) having excessive supplies of hydro power.

© Since there is a limit to untapped potential hydro power resources, the amounts of resources that can be exploited are limited.

© Since the cost of hydro power generation is low, hydro power hydrogen be­comes dominant in the early stages of the WE-NET practical utilization.

b. Solar power hydrogen® Since potential high-volume supply sources of hydrogen are desert zones, hy­

drogen supplier countries (regions) are limited to ones situated in desert zones (regions).

© Up until the year 2050, to which the analysis period extends,there are unlim­ited supplies of solar power hydrogen.

21

(D Since the cost of photovoltaic power generation is higher than that of hydro power generation, solar power hydrogen grows in demand as supplies of hydro power hydrogen near their limitations in terms of the exploitable hydro power resources.

Figure 3-2-1 is a conceptual graph depicting hydrogen supply. As to the use of the WE-NET hydrogen, hydro power hydrogen which is more cost-competitive is considered to become dominant in the early phases of practical WE-NET opera­tion. While on the other hand, the use of solar hydrogen is expected to proceed as supplies of hydro power hydrogen begin nearing a plateau due to limitations aris­ing from the available resources of hydro power. In order for the use of solar hydrogen to proceed, it is of course necessary for its comparably high initial cost to considerably come down to a level at which it can rival hydro power hydrogen on the strength of some innovative technology.

Supply of Hydrogen

Fuel: Upper Supply Limit on Hydropower Hydrogen

Solarpower Hydrogen

Hydropower Hydrogen

Fig.3-2-1 Conceptual graph showing hydrogen supply

(2) Adding hydrogen-related analysis capability to the model The GREEN model incorporates seven back stop technologies which are as­

sumed to become commercially available in the future by dividing them into the following three headings:

® Carbon based back stop (CBS)--Coal liquefaction, oil shale, etc.

® Carbon-free back stop (CFBS) - Biomass, etc.

(D Back stop electric option (ElecBS) - Solar energy, wind energy, nuclear fusion, etc.

22

WE-NET hydrogen is no different from back stop technologies,meaning that they are new forms of energy waiting to be put to practical use in the future. Based on the back stop idea behind the current model, it has been decided to integrate hydrogen energy into the model.To be more specific, the following three elements shall be added to the Green model’s energy structure as shown in Fig. 3-2-2.

CD hydro power hydrogen fuel

(D Solar power hydrogen fuel

© Hydrogen electric power generation

Hydrogen electric power generation reflects consideration given to the develop­ment of hydrogen combustion turbines, which represents part of the WE-NET project. As for hydrogen for use as fuel, hydro power hydrogen or solar hydrogen will be supplied.

OOPEnergy Additional Nesting in Modified GREEN Model

undle

Non-Electric

Oil +Gas +Hydrogen Fue undle

ElectricOil + Gas Composite Fuel

Hydrogen Fue Fuel Bundle

Hydropower So 1arpowerHydrogen Hydrogen

Hydrogen Electric Conv CFBSPower Generation

Crude 0i e f i n e d Natural GasComposite Fuel Composi te Fue Composite Fuel

CBS Conv CFBS CBS Conv CFBS CBS Conv CFBS

Fig.3-2-2 Energy nesting in modified GREEN model

(3) Program modification work and future themes of studyProgram modification work consists of the integration of hydrogen energy into

the model in order to impart the ability to analyze the impact of hydrogen energy use and the addition of computation years. As for the former, efforts have been underway with the target dates for completing basic work by the end of fiscal 1995. As to the latter, fundamental work has already been completed during

23

fiscal year 1994 by adding the years 2020 and 2040 to the original calculation years that were spaced at 20-year intervals beyond the year 2010 in order that the calculation years occur every 10 years.

During fiscal year 1995, the work to incorporate the ability to analyze hydro­gen energy use shall be continually carried out. Major themes are as follows:

(D Development of computer programs as to constraints on supply and supplier regions, that arise from the use of WE-NET hydrogen and resultant discrepan­cies from the current back stop idea.

® Study of analytical scenarios and input data concerning hydro power hydrogen and solar hydrogen.

© Investigation of basic GREEN model data for the sake of preparing input data.

24

3.3 National-level energy estimation and assessment

3.3.1 R&D GOALS

Hydrogen energy is expected to play an important role in a future energy sys­tem if many technologies related to hydrogen energy are combined effectively to constitute ’’hydrogen economy.’’ This suggests that system analysis from an en­ergy system point of view is indispensable to get plausible perspectives on the commercialization of the technologies to be developed in the WE-NET project The goal of this study is to draw country-level perspectives on production, trans­portation, and consumption of hydrogen energy. To achieve the goal, simulation studies on future energy systems are to be executed to assess their potential economic and environmental impacts.

3.3.2 Results in the preceding year

Surveying the energy models developed to date, we selected the MARKAL (MARKet ALlocation) model as a simulation tool to attain the above objective. The model can evaluate the mix of energy supply/demand technologies optimally meeting the specified demand. We then examined the model modifications re­quired to analyze energy systems including hydrogen energy. The study revealed that major modifications required were addition of hydrogen related technologies, modification of planning horizon, and simplification of the model to facilitate sen­sitivity analyses.

3.3.3 Results in Fiscal Year 1994

1. ObjectivesThe objective of the study in this year is to complete the above-mentioned modi­

fications of the MARKAL and to verify the capability of the modified model through sample studies.

2. Study ResultsThe MARKAL comprises the matrix generator program that describes the fun­

damental model structure, model data that exhibits detailed characteristics of various technologies, and report generator program that offers summary reports on the computation results.

(1) Addition of hydrogen-related technologies

25

Major technologies added are described below along with the required data for the technologies:a) Import of hydrogen - upper limit of the imported quantity, CIF price, etc.;b) Hydrogen turbine efficiency, capital cost, etc.;c) Additive to town gas - Upper limit of addition.

The technologies taken into account in the MARKAL are listed in table 3-3-1;in the table, the technologies are classified into the newly added ones, the already included ones, and the not considered ones.

Table 3-3-1 The technologies taken into account in the MARKAL

Type Technologies newly added

Technologies already included

Technologies not included

Pro­duction

NoneElectrolysis Thermochemical cycle Steam reforming

etc.

Solar chemical cycle etc.

Import Import None

Electric­ity

Hydrogenturbine

Fuel cell Conventional thermal, etc.

Conver­sion

Town gas synthesis

Methanol synthesis Delivery

Production of ammonia, etc.

Utiliza­tion

NoneIndustrial furnaceRaw materialsAircraft fuelAutomobile fuel

Rocket fuelReforming of oil, etc.

etc.

The model is applied to the studies on the effect of hydrogen import on genera­tion mix and emission of carbon dioxide. Fig. 3-31 depicts a sample result. The result shows that installed capacity of hydrogen based generation source in­creases and emission of carbon dioxide decreases as quantity of imported hydro­gen increases. This result suggests the validity of the above-mentioned modifica­tion of the model. It should be noted that the input data for the analysis is tenta­tive and requires much revision in the future.

26

500 1000 1500 1000 1500

5 30.00 ro 25.00 -£ 20.00 -uron 15.00 -CDU 10.00 -"□V 5.00 -15to 0 00c 0 500 1000 1500

Imported Hydrogen (1 OOOOt)

(a) Installed capacity hydrogen- related generation source

cs11.8011.60ID**o 11.4011.20

4 11.00o 10.80b

10.60 0 500Imported Hydrogen (1 OOOOt)

(b) Emission of carbon dioxide

Fig.3-3-1 Hydrogen import v.s. generation mix and emission of carbon dioxide.[Note] Values are for 2025.

(2) Modification of time horizonThe planning horizon of the MARKAL was from 1980 to 2025 in the last year

studies. However, if we consider the R&D schedule in the WE-NET project, hy­drogen energy will not be widely used until in the middle of the next century. This requires the modification of the planning horizon of the.MARKAL. On the other hand, if we could decrease the number of time periods (the number of the time periods has been fixed to be nine), we could greatly mitigate the computa­tional burden of the model. We thus modify the time periods of the model.

Although the decrease of the number of time periods would highly contribute to the relief of computational burden, the modification might cause the increase of errors described below:a) Increase of computational error and/or terminating effect;b) Increase of modeling error for the processes with lead time of some years in it -- e.g., nuclear fuel cycle.

Sample studies are executed to examine the effect of the modification. Fig. 3 3 2 depicts the effects of the number of time periods on installed capacities of elec­tricity generation sources. If we consider the uncertainties inescapable in the assumption of this kind of study, the results implicate that the errors due to the decrease of time periods are negligible. Studies on the topics such as nuclear fuel cycle can be, however, a few exceptions. The calculation with fewer time periods is, therefore, preferable in the study on hydrogen economy.

27

y go

1 1 1 222333333333333 4 5 6 1 6 C 1 2345689DEGH

□ 9 Time Sections

B 4 Time Sections

0 1 Time Sections

Generation Sources

Fig. 3-3-2. Effect of the change in the number of time periods on installed capacities of electricity generation sources

(3) Scale reduction of model by eliminating technologiesSensitivity analyses under various conditions are indispensable to estimate

market penetration of hydrogen energy to a future energy system. This analysis is, however, highly difficult to carry out because of the huge size of the model. We thus examine the possibility of reducing model size by eliminating the technolo­gies of little relevance to hydrogen economy. Sample studies are performed on the effects of reducing model size; the eliminated technologies in the sample study are listed in table 3-3-2.

Table 3-3-2 Eliminated technologies in the sample study.

Class Eliminated technologies

EnergyConversion

ElectricityGeneration

Part of central-type renewable energy(Solar thermal, wind and wave power, etc.)

High temperature gaseous reactor etc.

1 vvllllUlUgj

Conversion Part of coal conversion technologies (high cost type of coal liquefaction)

Demand TechnologyPart of iron factory technologies

(co-firing with coal)Part of energy conservation

Fig. 3-3 3 depicts a sample result. The results reveal that reduction described above brings little effect on the market penetration of hydrogen-related technolo­gies. The mitigation of computational burden is, however, not so prominent as that in the case of reducting the time periods.

28

□ Reduction Case

0 Original Case

EEEEEEEEEEEEEEEEEEEEEEE 00001 1 1 1 223333337788888 1 67A34561C1 2389B6C12ABC

Generation Sources

Fig.3-3-3. Effect of the reduction of technologies of little relevance to hydrogen energy.

3.3.4 Future themes of study

(1) Study on scenarios on energy system in the twenty-first century;

(2) Collection of related data and revision of the existing data;

(3) Improvement of report generator program.

29

3.4 City-level energy estimation and assessment

This report describes work undertaken within the first year of research car­ried out by the London Research Centre and Imperial College under the WE-NET Project (Phase I) - International Clean Energy Network Using Hydrogen Conver­sion.

3.4.1 R&D goalsSpecific objectives for Fiscal 1994 were:

• to review previous work and current research programmes on hydrogen of the European Community;

• to prepare preliminary conceptual designs; and• to agree a taxonomy of hydrogen technologies and to complete a preliminary

evaluation of them.

3.4.2 Fiscal 1994 R&D results(1) Review of previous and current research

A detailed review was undertaken of all relevant literature and databases relat­ing to hydrogen research carried out within Europe both under European Union programmes and by other institutions. The report includes a detailed appendix setting out the results of this research. The information gathered has been used in developing the conceptual design and, in particular, in providing the data on costs, efficiencies and the other characteristics of technologies used in the HY- RES model (see below).

(2) Methodology for conceptual designA suite of modelling tools has been developed known collectively as the BY­

RES model. The name signifies that it is based on the concept of the Reference Energy System, but that it is specific to hydrogen. Also that it is a high resolu­tion’ model in that it deals in detail with meeting the end use requirements for energy through the supply of hydrogen. Figure 3 4 1 shows the basic structure of the model.

The main inputs to the HY-RES model are:• data describing the energy requirements of the city, taking into account the

differing geographical characteristics of energy demand;• a conceptual design for the energy supply system, expressed as a conventional

Reference Energy System; and• data bases containing information on the main characteristics of the technolo­

gies utilized at the nodes of the Reference Energy System.

30

The HY-RES model can be used to calculate the energy balance, and the techni­cal and economic characteristics, of any conceptual design.

Data from theReferenceCity

Technologydatabases

ReferenceEnergySystem

tSystem

conceptualdesign

►Evaluation according to chosen criteria

Figure 3-4-1 Modeling methodology

Production Conversion Transmission Transmission Storage Conversion Distribution Storage Use

Hydrogen

1Heat

distribution!

Hydrogen

Metalhydrides

Electricity

Heat

-i Domestic | Commercial]

Industrial I

- Transport

Figure 3-4-2 Hydrogen Reference Energy System

The Reference Energy System used in the HY-RES model is shown in Figure 3- 4-2 and is a conventional representation of energy flows in a hydrogen system. The various operations of production, conversion, transmission, transmission, storage, conversion, distribution, storage and use are shown along the top of Fig­ure 3-4-2. Storage appears twice, because storage may either be in large quanti­ties at or near the points of production or in small quantities near the point of use. Transmission (or bulk transport) appears as two consecutive operations because transmission can often require consecutive operations such as pipeline transport and shipping.

The energy needs of domestic, commercial, industrial and transport activity results in a flow through the energy supply system, which is charted by the Refer­ence Energy System.

31

(3) The taxonomy of hydrogen technologiesThe classification or taxonomy of technologies has been derived from the speci­

fication of the Operation used in the HY-RES model. In this first phase of the project, the technologies included in each category represent those for which data are available in the literature. In later phases, the database of technologies will be reviewed and extended, with best estimates made of central values and ranges.

(4) The alternative system conceptsThe Reference Energy System was used to represent alternative conceptual

systems for the supply and delivery of energy to meet domestic, commercial, in­dustrial and transport needs. The concepts were deliberately chosen to be simple because the objective at this stage was to demonstrate the value of the approach and not to make detailed assessments of closely specified systems.

Within the city, it is possible to devise many different systems of energy distri­bution to meet the demand for energy services. For example, the demand for residential space heating could be satisfied by the direct supply of district heat from a Combined Heat and Power (CHP) plant, by distributing electricity to dwell­ings for use in individual space heaters, or by distributing hydrogen for use in individual fuel cells or boilers. Different patterns will be investigated during the course of this project, and assessed through consideration of the resulting energy balance. Two concepts have been investigated so far, and these are based on the Reference City

The Reference City is intended to provide a spatially differentiated description of the end-use activities governing energy demand in an urban environment. Ini­tially, a relatively small part of London, divided into nine lxl kilometre grid squares, was selected and the energy using activities were assessed according to historical records. The urban area chosen for study was Kingston-on-Thames. This is a town in the western suburbs of London which is characteristic of a large number of similar suburban centres, with a degree of local economic activity, but also acting as a dormitory town for London.

The objective in this initial phases of Subtask 3 was to develop the method­ological tools and to demonstrate their applicability. Two configurations were therefore selected for comparison which have characteristics of 'centralised’ and dispersed’ arrangements. Figure 3-4-3 show the spatial arangement of the two configurations.

(5) Comparison of costsA comparison was made of the costs of meeting the energy needs of the area

under these two arrangements. The most significant conclusion which may be

32

1. Centralised

Heat Electricity

2. Dispersed

Figure 3-4-3 Alternative spatial concepts for hydrogen system

33

drawn from this pilot study is that it is not possible to compare alternative hydro­gen concepts in terms of the cost per gigajoule of delivered energy, because the different efficiencies of different concepts and the different end-use costs distort such comparisons. The only fair comparison is between the total costs of meeting the energy demands of an urban area by different concepts. This means that a integrated, holistic approach such as that followed in the present study is essen­tial. Any methodology for meaningful comparison must include:

• a spatially differentiated description of energy demand;• an integrated supply balancing the demand for heat and power; and• a representation of the chain from primary production to end-use.

The methodology used here meets those requirements.Conclusions about the two concepts examined must remain tentative because

the data on the technologies is not yet complete and more work needs to be under­taken to improve the accuracy of the cost estimates. However, on the basis of the present results it appears that there is no significant difference in the total cost between the two concepts considered. On the other hand, there are significant differences in the final volume of delivered hydrogen, the thermal efficiencies of the respective supply chains, the cost per GJ of delivered hydrogen and the infra­structure needed to realise the concepts. The general conclusion is that cost differences between widely differing concepts may not be great, but that the sup­porting infrastructures are quite different. In this situation the concept which evolves most easily out of present energy supply structures may be preferred. Of the two concepts considered, the centralised concept appears to be the one which is most easily achieved from present practice.

(6) Energy balancesThere is not a striking difference between the volumes of total final energy use

in each case. The lowest total is for the centralised hydrogen concept. This is low compared to the conventional supply structure because of the significant reduc­tion in the amount of electricity used for space heating, and low compared to the dispersed hydrogen concept because final use is met with electricity and heat, and the conversion losses have been absorbed upstream.

Although the centralised hydrogen concept requires the lowest volume of en­ergy delivered to the consumer, it requires the greatest amount of energy deliv­ered at the city boundary. This is because of the conversion losses in the central fuel cell, the heat only-boilers and the storage and distribution of liquid hydrogen, all of which occur within the city boundaries.

The structure of energy in final use is significantly different in each case. In the conventional case there is a mixed fuel supply, with natural gas predominant.

34

In the dispersed hydrogen concept it is predominantly gaseous hydrogen and in the centralised hydrogen concept it is mainly heat and a significant quantity of electricity.

The great difference between the infrastructure requirements of the two hydro­gen concepts is important as it suggests that it will be difficult to maintain a commitment to both options in the same area because the infrastructure specifica­tions are entirely different

(7) Environmental impactsThe environmental impacts for the two hydrogen concepts and the conventional

supply system were compared. It is assumed for the conventional supply concept, that electricity generated outside the city is produced from Combined Cycle Gas Turbine (CCGT) plant at 45% efficiency. As is to be expected, the environmental impacts from either hydrogen concept are much less than from the conventional concept. The dispersed hydrogen concept produces less NOx than the centralised concept because of the continued reliance on internal combustion engines for transport in the centralised concept.

(8) Relationship to other modelling work within Subtask 3Other models are being used within other activities undertaken as part of

Subtask 3. The GREEN model, developed by OECD, is being used to analyze the global economy and its consequences for energy trade. The MARKAL model is being used to estimate the future structure of energy demand, costs and environ­mental impacts at a fairly large scale. The HY-RES model complements these studies by providing technology assessment at the level of the city and permitting a more effective assessment of the influence of spatial considerations on techno­logical choice.

35

MODELS

Details oftechnologicalsystems

GREEN

MARKAL

HY-RES

▲^_______

REFERENCECITY

Global economies and trade

Terms of trade for hydrogen

Aggregate cost structures and environmental impacts

Prices and availability of hydrogen

Spatial influence and technology choice

Impact of fuel availability and price changes on energy demand

Land use, transport and energy demand interaction

Figure 3-4-4 Relationship between modelling activities

The relationship between these models is shown in Figure 3-4-4. It is not proposed, at this stage, that there should be a formal linkage between HY-RES and the other modelling activities, nor that data should be transferred from the MARKAL to the HY-RES model, but the diagram provides a useful illustration of the relationship between the modelling elements. Eventually, at a much later stage of maturity, a formal linkage with transfer of data could be envisaged.

(9) Overall conclusionsThe methodology proposed here is both necessary and suitable for the examina­

tion of hydrogen concepts. It is necessary because the spatial details of the final demand have a determinant effect on the choice of technological chains of energy supply and these can be transmitted back as far as the primary production of hydrogen.

The only valid economic criteria for comparing hydrogen concepts is the total cost, from production to use, in satisfying the energy-related needs of the area. On this criterion of total cost there seems to be little to choose between the two concepts so far examined. This is a tentative result because the data has not been fully validated and there are many possible concepts which have not yet been examined. If the conclusion is upheld by further work, then it will be important because it suggests that the most suitable hydrogen concepts may be those which

36

can be developed most easily from present supply structures. The ease of transi­tion from present structures may be the most appropriate criterion for choice of concept.

The HY-RES model is well adapted to search for the most cost-effective manner of introducing hydrogen into urban energy supply. Also, the model is a useful supplement to the other modelling tasks being undertaken within Subtask 3.

3.4.3 Priorities for FY95The work in FY94 has demonstrated the value of the method and underpinned

the development of suitable databases and system concepts. These still need to be refined and this will be continued in FY95.

Priority will be given to identifying the most effective ways of using moderate quantities of hydrogen in the medium term, rather than in identifying the optimum design of an energy sector entirely fuelled by hydrogen. Assessment of cost- effective means of introducing hydrogen will be the priority of the work in FY95. The HY-RES model can easily be adapted to address this problem. The Reference Energy System can be expanded to include both conventional energy technologies and novel hydrogen using technologies. The data for conventional technologies is easily available, so the Reference Energy System can be solved for economic and environmental criteria. On the basis of these criteria the most useful way of employing limited quantities of hydrogen can be identified.

The main objectives of for FY95 will be to:•develop alternative system concepts both in detail and complexity, especially in relation to the processes occurring within national boundaries;

•extend and complete the data bases, with especial reference to technologies ap­propriate to processes occurring within national boundaries;

•identify the environmental improvements resulting from the use of hydrogen in various applications;

•identify reference urban environments to be studied, and develop an interface between the HY-RES model and these references; and

•analyse the most cost effective strategies for incorporation of hydrogen into ur­ban energy systems, taking into account the environmental benefits. Draw con­clusions relating to the appropriate scale and location of hydrogen using tech­nologies.

37

3.5 Safety measures and assessment

3.5.1 Targets of R&DThe first phase of this development project aims to sample contingent trouble

and accident events in each of the WE-NET systems that will be built in the years ahead. Based on estimated effects of such events, a study will be conducted to find the safety function the system should have, and then an attempt will be made to work out a basic strategy for ensuring safety from the viewpoint of risk preven­tion. To attain these objective, a research team has been assigned to conduct necessary surveys and studies. In addition, a committee, consisting of experts from various sectors concerned and researchers directly involved in development tasks, has been organized to carry out research activities on safety designs, study specifications for safety analyses and evaluate the analysis findings.

Prior to these assessments, the collection and filing of relevant data started in fiscal 1993 were continued in fiscal 1994, the second year of the first phase, followed by the commencement of research activities to develop a simulation code which appears useful for safety evaluation. The following are the items covered by these surveys and studies:

3.5.2 Study and evaluation of safety designs(1) Survey on current state of safety designs, cases of accidents and applicable

laws and specificationsA survey was conducted on the methods of system safety design actually used

at such facilities as chemical and energy plants, followed by an analysis of their features. Also cases of accidents involving liquid hydrogen in Japan were sur­veyed, but since no published report was available, information was gathered on cases of troubles and the details of plant safety designs through interviews with special institutions or experts in this line. In addition, a survey was carried out on cases of accidents, including those involving gaseous hydrogen, in other coun­tries (e.g., a 1988 explosion at a North Sea gas field resulting in 165 deaths). An attempt was also made to find what are required for liquid hydrogen storage and consumption facilities under the application laws and specifications now in force.

(2) Identification of contingent trouble and accident events in each category ofWE-NET systemsResearch efforts in fiscal 1994 were focused on gathering information on the

designs of hydrogen production plants (water electrolysis) and storage facilities (liquid tanks). First of all, the scope of research in this area was confined to identifying and analyzing the hazards of gaseous and liquid hydrogen and to

38

3.5.3 Prearrangements for safety analysis of various accidents(1) Collection of information required for safety analysis

Following research on relevant Japanese literature in fiscal 1993, a survey was conducted in fiscal 1994 on similar materials in the United States to collect useful information for safety analysis (including manuals on safe handling of hydrogen issued by the National Aeronautics and Space Administration or related organiza­tions). Literature on a l,500gallon liquid hydrogen leak test, among other experi­ments on a relatively large scale, was studied and analyzed in detail to provide useful data for computer simulations.

(2) Development of simulation programsThe subtask group set about the development of a simulation code for preparing

models of changes in the distribution of hydrogen concentration resulting from the vaporization and dispersion of liquid hydrogen when it began leaking. Re­search activities were also commenced to improve a simulation code capable of assessing the effects of compressed gas tank explosions on structures and humans around the tank sites, so it will be applicable to hydrogen gas.

3.5.4 Future themes of studyIn the years ahead, surveys and studies will be continued on the safety ideas,

objectives and design guidelines which are considered necessary in specifying the safety function for each category of WE-NET systems. Most of necessary surveys on cases of accidents and the applicable laws, specifications and stan­dards had been completed by the end of fiscal 1994. However, a look at the current state of safety management at existing plants in Japan and abroad in­dicates that finding and analyzing the underlying philosophies of the applicable laws and specifications and safety rules under them is very useful in studying safety guidelines. Accordingly, these research efforts will be continued in the years to come. Meanwhile, contingent trouble and accident events in each cat­egory of WE NET systems will be identified with consideration given to the trends of related subtasks.

In the area of simulation models used as a safety evaluation technique, contin­ued efforts will be made to develop simulation models for leak or explosion behav­ior of liquid hydrogen based on the findings obtained up to fiscal 1994. It is expected that this will provide capability to estimate the effects of accident events assumed for WE-NET systems which will be built in the years ahead, and to feed back such information to safety measures.

working out a basic strategy for future studies on accident events.

39

4. Subtask 4 : Development of hydrogen production technologies

This study aimed at establishing a hydrogen production technologies by the solid polymer electrolyte water electrolysis that is expected to produce hydrogen at higher efficiency and lower cost than conventional hydrogen production tech­nologies, in the project of International Clean Energy Network using Hydrogen Conversion(WENET).

The study in 1993 was partly reconsigned to three incorporations having their own unique technologies before they started investigation for making high the characteristic performanceof water electrolysis cell.

In 1994, the study had two incorporations participated newly to carry devel­opments of the elemental technologies for the solid polymer electrolyte water elec­trolysis on the basis of their own unique cell types and of the synthesizing tech­nique of high temperature solid polymer electrolyte. The study does not include those investigation and developments, but also survey of the electrolyte water electrolysis technologies and economic evaluation of the hydrogen production plant by way of the solid polymer electrolyte water electrolysis to reflect to the study .

4.1 Survey of water electrolysis technologies

The survey of water electrolysis technologies was investigations of the current situation of water electrolysis technologies and materials for the cell to promote efficiently the development of hydrogen production technologies by the solid poly­mer electrolyte water electrolysis in the WE-NET project.

The solid polymer electrolyte water electrolysis has the following advantages.(a) The electrolyte is so stable that the cell structure can be made simply.(b) There is no corrosive electrolyte, allowing the reliability to be made high and

kept easily.(c) The ion exchange membrane works a pore free separator so that the gas can be

separated easily, providing highly pure product gas.(d) The current density can be made higher than the alkaline water electrolysis,

providing higher operation efficiency.However, solid polymer electrolyte water electrolysis involves the following

future technical problems to be further studied.(a) Higher characteristics and stability of the electrode materials(b) Higher characteristics of the solid polymer electrolyte membrane(c) Increase of temperature of electrolysis

40

Further, the survey arranged current and future subjects of electrode materi­als, including metals such as platinum, gas diffusion electrode, and ceramics elec­trode. The survey also made consideration of the ion exchange membrane and oxide composite diaphragm.

4.2 Economic evaluation of the hydrogen production by way of the solid Polymer electrolyte water electrolysis

The study investigated effects of the current density and energy efficiency to the hydrogen production cost by the solid polymer electrolyte water electrolysis plant. The study then evaluated economy of the plant to verify validity of the development target.

4.2.1 Details of the investigation

(1) Conditions to the Investigation- Amount of hydrogen production: 32,000 Nm3/h (see remark)- Current density : 1 and 3 A/cnf (development target in WE-NET)- Energy efficiency: 90 % (development target in WE-NET)- Electrode area : 1 to 3 m2 (development target in WE-NET)

Remark: Basic unit for calculation of the facility cost used for the economic evaluation of hydrogen supply system in the "Survey on Hydrogen Combustion Turbine” consigned under Sunshine program 1992

(2) Results of the Investigationa. Construction costs of the plant

Table 4-1 construction costs of the plant(Unit: billion Yen)

Type Solid Polymer Electrolyte Alkaline

Current density 3 A/cnf 1 A/cnf -

Equipment cost 5.23 10.8 15.7

Working cost 1.57 3.2 4.3

Plant cost (Total) 6.8 14.0 20.0

41

b. Hydrogen production cost

Fig.4-1 Current Density vs. Hydrogen Cost

£ 30

8S

20

oMH-

Energy Efficiency:90X

5 Yen/kWh

2 Yen/kWh -O-------O-

900 " 70 75 80 85

Energy Eff iciency(X)Fig.4-2 Energy Efficiency vs

Hydrogen Cost

4.2.2 Conclusions- The construction costs are competitive enough to the conventional alkaline wa­ter electrolysis production plant.

- To decrease the hydrogen production cost, it is effective to make high the current density, while increase of the energy efficiency does not contribute so much.

4.3 Development of the element technology by non-electrolytic plating

4.3.1 Investigation of the element technology with small cell evaluation apparatus

(1) Fabrication of small cell evaluation apparatusTo make the evaluation tests of small cells with electrode area of 50 cnf, an

evaluation apparatus of the following specifications was fabricated on the basis of the plan made in the previous fiscal year.- Electrode area: 50 cnf- Current density: 0.2 to 3 A/cnf- Number of stack: 1 pc- Electrolysis temperature: up to 80 *C- Electrolysis pressure: atmospheric pressure- Water supply: 0.05 to 0.5 1/min.

42

(2) Fabrication and evaluation of membrane electrode assembliesThe company fabricated membrane electrode assemblies with electrode area of

50 cm2 before having carried out evaluation and analysis of the following items. As a result, the company confirmed that the water could be elctrolyzed with these membrane electrode assemblies up to 3 A/cnf of the target value of the project. The maximum energy efficiency obtained was around 84% at 1 A/cm2 and around 73 % at 3 A/cnf.

a. Fabrication method of the test membrane electrode assemblyThe test membrane electrode assembly was fabricated by way of an adsorption

reduction growth method that was a variation of non electrolytic plating method used.

b. Effects of electrocatalyst electrode materialsThe company carried out electrolysis characteristic performance tests with

platinum and iridium used as kinds of electrocatalyst. It was found that if both the anode and cathode had iridium, the best characteristic performance was ac­complished. It was also found that if the anode had no iridium, the cell voltage was increased.

c. Effects of the current collector material structure (Fig.4-3)The standard current collector used was of platinum-plated expanded titanium.

Since it was seen that the contact area became narrow, the company made evalu­ations of the current collectors of titanium fiber sintered metal with platinum plating and titanium fiber sintered metal covered with titanium powder by flame spraying with platinum plating. The company confirmed that the latter had the cell voltage decreased.

—Q- Pt Plated Ti Mesh —O- Pt Plated Sintered Ti —A- Pt Plated Sintered Ti with

Thermal Spray Coating

1.8 —

1.6 —

Current Density (A/cm2)

Fig.4-3 Effects of current collector material on I -V characteristics

43

2 in H

a En

ergy

C

urre

nt

Cel

l(p

pm)

Effic

ienc

y (.%

) Effic

ienc

y (%) Volta

ge (V)

d. Effects of electrolysis conditions (Figs. 4-4 & 4-5)The company carried out electrolysis in a current density range of 0 to 3 A/ cnf

before having evaluated effects of the current density. The cell voltage increased linearly in higher range than 1 A/cnf. The cell voltage was decreased and the energy efficiency was increased with the electrolysis temperature, although the current efficiency was decreased.

97 -

96 -

Current Density (A/cm2)

Fig. 4-4 Effects of current density on cell characteristics

I________ i________ i________ i________ i30 50 70 90

Temperature (°C)

Fig. 4-5 Effects of temperature on cell characteristics

4.3.2 Technical investigation of larger scaleThe company extracted technical problems of manufacturing facility and evalu­

ation apparatus associated with larger membrane electrode assemblies and searched solutions for them. The problems included creation of fabrication tech­nique of the larger membrane electrode assemblies and creation of the cell struc­ture and assembling method to make uniform flow in the cell, the current distribution uniform, and the contact pressure.

4.4 Development of the element technology by hot press method

To achieve higher the efficiency and current density in the solid polymer elec­trolyte water electrolysis, the company investigated in this year (1) fabrication of the membrane electrode assembly and composition of electrode and (2) structure of the current collector, close contact of the current collector with the membrane electrode assembly and structure of the cell frame. Also, the company designed

44

and constructed test stands to evaluate life performance of the membrane elec­trode assembly.

4.4.1 Fabrication and evaluation of the membrane electrode assembly

The company investigated fabrication of the electrode, bonding of the electrode to the membrane, amount of electrocatalyst in the electrode and effect of addition of Teflon and ion-exchange resin into the electrode. The company fabricated the membrane electrode assemblies having 50 cnf electrode area. The company tested all incorporating the assemblies and obtained the following results.(a) Iridium dioxide was most superior as an electrocatalyst for anode.(b) The cell voltage was increased if amount of the electrocatalyst was less than2

mg/cm.(c) The cell voltage was not affected by addition of Teflon which was added to

increase the bonding strength of the electrode.(d) The cell voltage decreased a little by addition of the ion-exchange resin, al­

though it was added with the intention of raising the cell voltage.(e) The cell voltage decreased with electrolysis temperature increase.

4.4.2 Investigation of the cell structureThe company investigated structure and contact pressure of the current

collector and structure of the cell frame with use of 50 cnf cells. The company obtained the following results.(a) The titanium fiber sintered plates were superior to expanded metal meshes as

a current collector.(b) Optimum contact pressure of titanium fiber sintered plate to the current

collector was 20 to 25 kg/cnf.(c) Generated gases exhausted well with the cell having grooves of 2 mm wide and

3 mm deep at intervals of 4 mm on the cell frame and with exhaust pipes of 6 mm inside diameter placed on the frame.On the basis of the investigation results, the company fabricated the cell with

50 cm electrode area before having carried out a water electrolysis test at atmo­spheric pressure and 80°C. The resulted cell voltage, as shown in Fig.4-6, was 1.62 V at the current density of 1 A/cm and 1.83 V at 3 A/cnf.

45

2

K

o

<3

1.9

1.8

1.7

1.6

1.5

1.4

El(Anc

jctroxje T

de Aremp.

ea 580

Ocm2

SC

0 0.5 1 1.5 2 2.5 3 3.5Current Density(A/cm2)

Fig.4-6 Performance of the laboratory cell

4.4.3 Construction of the test stand for life evaluationTo evaluate durability of the cell having high electrolysis characteristic perfor­

mance, the company investigated the system configuration, water circulating method and temperature regulating method and constructed test stands of the following specifications for evaluating cell lives.- Electrode area: 50 cnf- Current density: up to 3.0 A/cnf- Number of stacking cell: 1 pc- Electrolysis temperature: up to 80- Electrolysis pressure: atmospheric pressure- Water supply: natural circulation by gas lift

Fig.4-7 shows intermediate results of the life test carried out for the cell having 50 cnf electrode area with use of the test stand. The cell had iridium dioxide as an anode electrocatalyst and platinum black as a cathode electrocatalyst. The cell voltage was 1.67V in 470 hours after the start of the life test. The current efficiency was so good as 97.9 % which was calculated from the amount of gener­ated hydrogen gas.

46

50 100 150 200 250 300 350 400 450 500Time (Hi

Fig.4-7 Cell performance vs. time

4.5 Development of the element technology by porous sintered electrode

To make the efficiency and the current density higher in the development of water electrolysis cell using solid polymer electrolyte, the company studied the electrode and the solid polymer electrolyte that were important components for the cell.

In this year, the company designed the basic structure of porous electrode. On the basis of the design, the company tried to set up the water electrolysis system and carried out electrolysis experiments. The company also tried to increase the heat resistance of the solid polymer electrolyte, particularly in improvement of Nafion.

4.5.1 Experimental preparation

(1) Preparation of the porous electrodeThe company prepared the electrode sintered under various conditions and

studied effects of particle size of raw powder, sintering temperature and sintering time on the cell voltage, gas permeability, water permeability and mechanical strength. Then the company evaluated the differences of the porous electrode with the sintering condition. As a result, it was found that a good condition suitable for the electrode were 150 (i, 850 °C and around two hours. No marked characteristic changes with the sintering time were observed in the range of tests.

47

Cell Voltage CV]

(2) Selection of catalysts and plating methodsThe company compared smooth plated platinum with platinum black for the

cathode electrocatalysts. Platinum black showed lower cell voltage. The com­pany also tested Pt, Ir, Ir02, Ru02 and mixed oxides for the anode electrocatalysts. Then it was found that Ir02 and Ru02 were suitable catalysts for the anode. Since it was anxious that Ru02 might be soluble, further study will be continued in future.

4.5.2 Studies on the water electrolysis system

(1) Set up of the 50 cnf Water Electrolysis System (Fig. 4-8)Based on the results mentioned above, the company set up the cell with 50 cnf

electrode area and carried out electrolysis tests. The cell voltage of the system coincided well with a result of a beaker-scale test made for the cell with 2 cnf electrolysis area. Any changes of the performance was not observed with the electrode area made larger.

The system achieved the energy efficiency of 80 % at 1.0 A/cnf of current density.

Sintering Conditions Particle Diameter : 150/im Temperature : 850°C Sintering Time : 2hr

Water Electrolysis Conditions Electrode area '• 60.Bed Cel I Temp. : 80°cElectrolyte : Nafion117 Cathode catalyst '• IrOz Anode catalyst : Pt-black

.0 1.0 2.0 3.0 Current Density [A/cnD

a case of beaker scale test

50cnf water electrolysis cell

Fig.4-8 Experimental Result of 50cm2 Water Electrolysis Cell

(2) Life test systemTo examine long-term characteristic changes of the materials used for current

collector, electrocatalyst and electrolyte that are components of the water elec­trolysis cell, the company made the life test system and has been carrying out continuous water electrolysis experiments.

48

4.5.3 High-strength solid polymer membrane electrolyteTo develop high heat resistant solid polymer electrolyte, improving of Nation

and sulfonation of other heat resistant resins were investigated. The polymer membrane having characteristics as an electrolyte equal to Nation even at high temperature was obtained by blending the heat resistant resin. That is,the mem­brane is expected to have a mechanical strength at high temperature.

4.6 Development of the element technology by zero gap method

The company carried out selections of solid polymer electrolyte (ion exchange membrane), anode and cathode electrocatalysts, electrolysis cell and cell compo­nent materials. Subsequently, the optimization of the cell structure has been in­vestigated by surveying, analyzing and examining previous techniques given in references and documents.

4.6.1 Cell structureAs a result of the survey and investigation of the cell structures and cell compo­

nent materials, the company proposed a water electrolysis cell prepared by the zero gap method that a solid polymer electrolyte (ion exchange membrane) was put in between the electrocatalysts supported on current collectors. This method has superior advantages: (1) the electrolysis membrane can be selected or replaced as desired and (2) the electrolysis cell can be easily assembled or disassembled or maintained.

4.6.2 Electrode materials and electrocatalysts(1) As to the preparation of the anode current collector, iridium powder or mix­

ture of iridium oxide and ruthenium oxide derived by the thermal decomposi­tion was mixed with a blend liquid of Teflon and Nation and subsequently hot- pressed on the porous titanium fiber substrate. It was found that the porous titanium fiber substrate had a good permeability of water and gas at high cur­rent density and a superior electrical conductivity. In addition, the anode cata­lyst derived from the oxide mixture of iridium and ruthenium oxides exhibited the highest electrocatalytic activity.

(2) As to preparation of the cathode current collector, the cathode electrocatalysts such as platinum powder, platinum supported on carbon powder and thermally decomposed platinum and ruthenium powders mixed with solvent naphtha or Teflon liquid were supported on the carbon cloth or porous stainless fiber substrate and examined.

49

4.6.3 Survey of the solid polymer electrolyteThe company performed the characterization of several membranes such as a

perfluorosulfonic acid, improved perfluorosulfonic acid, perfluorocarboxylic acid, single sided chain perfluorosulfonic acid and ethylenetetrafluoroethylene polymer types.

4.6.4 Trial designing of water electrolysis apparatusTrial designing for the estimation on long-run stability of a water electrolysis

cell with 150 cof electrode area was performed.

4.6.5 Extraction of problems with scaling upThe company made clear technical problems with the application of the cell

structure and plant facility to the larger scale water electrolysis apparatus and investigated a conceptual structure of it. The expected technical problems in making the larger water electrolyzer include(a) Optimization of cell structure- Supporting technique of electrocatalysts on the larger surface of the electrode- Homogeneous junction of the larger scale electrode with solid polymer electro­

lyte membrane- Stacking structure of the cells that provides high current density and minimum

internal contact resistance.(b) Optimization for plant facility- Homogenous water supply to cell and measurement of water flow- Collection of evoluted hydrogen and oxygen and its control

4.7 Development of high temperature solid polymer electrolyte

The company is developing novel high temperature high strength solid polymer electrolytes for use in high temperature electrolyzers. The ultimate goal of this project is to develop solid-state, high temperature PEM electrolyzer that pro­duces hydrogen more efficiently than existing PEM electrolyzers. The basis of this cell is a solid polymer electrolyte that will operate at high temperatures(200 ~ 300*0). The performance goals are a coulombic efficiency approaching 100% and energy requirements of ~3.2kWh m3 of H2 at 2A/cnf and^3.8kWh m3 of H2 at 3A/cnf. The company expects that the development of solid polymer electro­lytes that operate at moderate to high temperature will leads to significant in­creases in the efficiency of water electrolyzers, because the electrical efficiency of steam electrolysis increases with temperature, owing to the decrease in both thermodynamic(open circuit) potential and electrode polarization (so that the ki­

50

netics at the electrodes are considerably faster). Commercially available perfluorinated hydrocarbon sulfonate ionomers are known to be chemically un­stable at temperatures higher than 100~~150°C and therefore cannot be used for this application.

The company has synthesized novel high temperature solid polymer electro­lytes that are thermally stable up to about 450“C in air(Fig.4-9). The thermal stability of these polymers represents a tremendous improvement with respect to commercially available perfluorinated hydrocarbon sulfobate ionomers presently used in electrolyzers. The good film forming properties of the new solid polymer electrolytes have been demonstrated. These solid polymer electrolytes were pre­pared from monomers newly synthesized by the company.

a new solid polymer electrolyte

Nation®

TEMPERATURE (°C)

Fig.4-9 Thermogravimentric analysis of solid polymer electrolyte and Nation under a flow of humid air.

51

5. Subtask 5 : Development of hydrogen transportation andstorage technology

5.1 Development of Large capacity hydrogen liquefaction facilities

The author made investigation of the current situation of the large hydrgen liquefying equipment in the last fiscal year, particularly in surveying and dis­cussing the technical documents.

5.1.1 Liguefying capacity and process efficiencyThe last investigation could not make clear in detail the hydrogen liquefying

process at a scale of 300tons per day that is expected in the present investigation. In the present investigation, he carried out procsss calculations specifically.

To make the process calculations, the hydrogen liquefying capability has to be decided in advance.

The present investigation assumed that the electric power capacity of each hydrogen-combustion turbine was 500 MW, the heat exchange efficiency was 60%, and the liquefying equipment operating efficiency was 90%. It also assumed that the necessary liquid hydrogen was 600 tons per day with use of two liquefy­ing equipments of the plant. The liquid hydrogen therefore was 300 tons per day with one liquefying equipment.

As for the process efficiency directly related to the unit power consumption of the liquid hydrogen, it made use of the survey investigation carried out in 1974 by Strobridge1*. The Strobridge’s survey depicted in percent Carnot the process efficient of the cryogenic process excluding the air separator. Strobridge showed a diagram that correlated the process scale with the process efficiency in which the process scale is converted to freezing at 4.2K. The author compared the corre­lation diagram with the large-scale helium refrigeratorliquefier that was con­structed and a large-scale helium refrigerator liquefier that was in the planning stage. He comfirmed that the correlation diagram could be used for the present cryogenic process. Fig.5 11 depicts a curve illustrating a relationship between the liquefying capability and process efficiency in which the freezing capability at 4.2K is converted to hydrogen liquefying capability.

The figure shows that the process efficiency of the hydrogen liquefying equip­ment of 300 tons per day is approximately 35%. The present investigation was made to aim the process efficiency at 40%. Fig.51-2 depicts a curve illustrating a curve of the unit power consumption of liquid hydrogen with respect to the percent Carnot. The figure shows that the unit power consumption of liquid hy-

52

drogen is 0.92kWh/Nm3 when the process efficiency is 40%.

100. 00

IE-5 IE-4 IE-3 IE-2 IE-1 IE+0 lEtl 1E+2 1E+3Capability of Liquefying [t/day]

Fig. 5-1-1 A curve of the percent Carnot with respect to the capability of hydrogen liquefying.

Fig. 5-1-2 A curve of the unit power consumption of liquid hydrogen with respect to the percent Carnot.

The investigated liquefying process includes a helium Brayton cycle and hydro­gen Claude cycle. For the hydrogen Claude cycle, the author also inspected a cryogenic compression process so that we can use a centrifugal compressor used for the large equipment besides the ordinary room-temperature compressor.

For the process calculations, the author assumed that the adiabatic efficiency of the expansion turbine was 85%, the adiabatic efficiency of the compressor was 80% at any of the room and cryogenic temperatures, and the raw hydrogen gas to be liquefied was at l.OSatm and supplied at room temperature. The process calcu­lations included a power consumption of the liquefying process that had to in­crease the pressure of raw hydrogen gas if needed. The liquid nitrogen used as auxiliary coolant was included the process efficiency calculation in which it was converted to power consumption of 0.5kWh/Nm3.

53

As a result of the investigation, it was made clear that the helium Brayton cycle had lower efficiency than the hydrogen Claude cycle. The author therefore car­ried out the investigation of hydrogen Claude cycle with the process pressure changed.

Fig.51-3 and 51-4 depict circuit diagrams illustrating the process of the hy­drogen Claude cycle of the room-temperature compression carried out in the present brief investigation. The both liquefying processes used a continuous con­version to convert the ortho-hydrogen to para hydrogen.

Recycle compressorRaw hydrogen

Low-temperature nitrogen gas

Liquid nitrogen

Liquid hydrogen storage

The marks of equipments

J^j : Compressor

/\ : Expansion turbine

: Expansion valve

: Ortho-para convertor

I I : Heat excahnger

f%l : Ortho-para converting catalyzer filling

Fig. 5-1-3 Arrangement process of the raw hydrogen expansion turbines.

Recycle compressor

Gas nitrogen

Raw hydrogen

Liquid nitrogen

ammonia freezer

Liquid hydrogen storage

Fig. 5-1-4 A two-stage expansion process.

In order to increase the process efficiency, the process shown in Fig.5-1-3 has the expansion turbines arranged also in the raw hydrogen line to make use of the high pressure of the raw hydrogen. The process shown in Fig.5-1-4 uses a two-

54

stage expansion in the recycle system to prevent the expansion from increasing the energy loss.

The process also uses an ammonia freezer for cooling the raw hydrogen system to make the cooling at as high a temperature level as possible.

The process efficiency was obtained with the process pressure changed. As a result, the process efficiency was made high with the pressure being made high in the both processes.Table-5-11 shows investigation results for the highest process efficiency in the range of the present process investigation.

Table 5-1-1 Brief investigation results of the hydrogen liquefying process of 300tons per day.

Process Arranged process of the raw hydrogen expansion turbines

(Fig.-3)

Two-stage expansion process

(Pig. -4)Raw hydrogen pressure 50 atm (5. 07 MPa) 30 atm (3.04 MPa)Recycle high pressure 50 atm (5. 07 MPa) 60 atm (6. 08 MPa)Recycle low pressure 8.3 atm (0.84 MPa) 6. 0 atm (0. 61 MPa)Required power 113 MW 115 MWPercent Carnot 44 % 43 %

As shown in Table-5-1-1, the hydrogen Claude cycle of the room-temperature compression was higher than 40% that was the target efficiency.

Fig.5 1-5 depicts a circuit diagram illustrating the cryogenic compression pro­cess with use of the centrifugal compressor with the density increased when the hydrogen gas of low molecular weight is at low temperature.

As shown in the figure, the cryogenic compression was made at the liquid nitro­gen temperature, and the compression heat was removed by the latent heat of the liquid nitrogen. The pressure of the raw hydrogen entering the process was set at 30 atm (3.04 MPa). The pressure was increased by the room-temperature com­pressor. In the process calculation, the power consumption of the compressor was made less to around 35MW. However, the consumption of nitrogen was as much as around 100MW, the process efficiency was only 34% that was lower than the target efficiency.

55

5.1.3 Elements of the equipments investigationThe imporotant machines, including the expansion turbines and compressors,

were investigated briefly as to whether or not the adiabatic efficiency assumed in the process investigation could be obtained.

The design conditions given to the expansion turbines and compressors were based on the cryogenic compression process shown in Fig.5-1-5 in view of the investigation of also development elements of the equipments. Because it is thought that the cryogenic compression process has larger number of issues than the room-temperature compression process, we firstly start the studies of the important machines for the cryogenic compression process in this fiscal year.

Table 51-2 shows results of the investigation with the expansion turbines used being reaction turbines having high efficiency.

Table 5-1-2 Results of the investigation of the expansion turbines

T1 T2 T3 T4

Flow rate [kg/s] 9.0 10.4 0.75 3.5Inlet pressure [atm] 20 20 20 30Inlet temperature [K] 82 50 29 29Outlet pressure [atm] 4 4 14.5 21.4Outlet temperature [k] 48 28 29 25Number of stages 2 1 1 1Impeller diameter [mm] 150 150 50 75Revolution frequency [rpm] 53,000 60,000 68,000 46,000

56

For the adiabatic efficiency, there are development elements that have not been solved yet. However, the efficiency of 85% assumed in the process calculation could be accomplished with future consistent research and development.

For the investigation of compressors, it was used the centrifugal type both for the room-temperature and cryogenic compressions. The stages was to a relatively low circumferential speed of 350m/s except for the first stage of the room-tem­perature compressor.Table 5-1-3 shows some results of the investigation.

Table 5-1-3 Results of the investigation of the compressors

C 1 C 2 C 3Flow rate [kg/s] 21 0.8 3.5Suction pressure [atm] 4 1.1 1.1Suction temperature [K] 82 82 306Dischage pressure [atm] 20 4 30Number of stages 8 6 36Impeller diameter [mm] 490-870 210-320 290-750Revolution frequency [rpm] 13, 0000—7, 700 21, 0000-31, 000 10, 0000—26, 000

If one unit of room-temperature compressor is used, the first stage impeller diameter was 1,060mm. Two compressors were arranged in parallel in view of strength. It was expected that the adiabatic efficiency was higher than 80% as assumed in the result of process calculation. The efficiency has to undergo further research and development as with the expansion turbines.

As described above, the author calculated the hydrogen liquefying process of 300tons per day although that was brief one. He could obtained the approximate dimensions of the expansion turbines and compressors that were important ma­chines. It could be also found that the target process efficiency of higher than 40% for the room-temperature compression process could be obtained although the process efficiency was based on various assumptions.However, to make the process efficiency high, the process pressure has to be made high. The expansion turbines and compressors should be subject to severe design conditions. Since the process flow rate is predicted high, the cryogenic compres­sion process having the centrifugal compressors investigated to use consumes much energy to remove the compression heat, resulting in deterioration of the process efficiency. Therefore, to use centrifugal type suitable for large-scale com­pressors, it is insufficient to simply make the temperature low to increase the density. Further investigation has to be made in future.

The present process investigation assumed conditions besides the adiabatic

57

efficiency of the expansion turbines and compressors. To increase the accuracy of process efficiency, we have to examine the assumed conditions for validity.

The expansion turbines and compressors also have to be investigated as to not only the thermodynamic characteristics associated with the adiabatic efficiency, but also important engineering factors, such as bearing load and type, and method of their research and development.

References1) T.R.Strobridge, ’Cryogenic Refrigerators on Updated Survey’, NBS Technical

Note 655 (1974).

58

5.2 Development of the liquid hydrogen transportation tankerThe studies we made last fiscal year(fiscal 1993) include:

(1) Study of properties of liquid hydrogen(2) Study of data on tank material, heat insulation material and support material(3) Study of the current situations on LNG carrier and on-land hydrogen tank

technologies(4) Study of technological issues on liquid hydrogen tanker(5) Study of related documents

We have continued the study of the related documents and performed concrete test design. Furthermore, we have made the following studies this fiscal year in an attempt to define technological issues of the liquid hydrogen tanker more clearly.

5.2.1 Study of basic requirements(1) Capacity of cargo tank

When a 1,000MW class power plant uses 1,200 tons of liquid hydrogen per day,the required capacity is 14,000 tons/tanker = 2 00,000 nf/tanker, consider­ing the loss by boil off gas, assuming that a round voyage requires 20 days and two tankers are used to load every 10 days.

(2) Number of cargo tanksConsidering the arranging factor to keep ship balance in voyage, equiping fac­

tor for piping, stability in damaged condition, we set up 4 tanks for spherical tank system and 2 tanks for prismatic tank system.

(3) Ship typeConsidering the required ship speed, mono-hull ship as present LNG tanker can

be used. But the cargo is so light hydrogen, large capacity and small displacement ship is preferable. Therefore, we study not only mono-hull ship but also twin-hull ship which has these characteristics.

(4) EnduranceWe set up the endurance of 6,000 nautical miles which covers the distance of

almost routes.

(5) Cruising speedBecause we assume the 10 days voyage for 6,000 nautical miles, cruising speed

is 20^-25 knots.

59

(6) Boil off rateWe set up boil off rate on the assumption that boil off gas is used for fuel of

main engine. Assuming that gas burnning ratio is 20 ~40%, we set up that boil off rate is 0.2 ^-0.4%/day.

(7) Hydrogen characteristics which is used for studiesHydrogen characteristics are shown in Table 5-21 comparing with

LNG(methane).

Table 5-2-1 Hydrogen characteristics

liquid hydrogen LNG(methane) column

boiling point -253 °C -163 °Cliquid specific gravity 71 kg/m' 424 kg/m3 boiling pointlatent heat of vaporization 447 kJ/kg 510 kJ/kg boi 1ing pointexplosion limit 4 - 76 % 5 - 15 % atomosphereminimum ignition energy 0. 02 mJ 0. 28 mJ atomospherehigher calorific value 142.060 kJ/kg 56. 000 kJ/kghigher calorific value 12. 770 kJ/m3 45, 920 kJ/m3 gas(0 °C, latm)higher calorific value 10, 086, 260 kJ/m3 23, 744, 000 kJ/m3 liquid

5.2.2 A study on elementary technologiesBased on the technologies of LNG carrier, we studied each feature technology

and defined the issues.

(1) Presumption of ship type and engine horsepowerIn case of mono-hull ship, liquid hydrogen tanker has smaller draft than LNG

tanker, because of its light cargo. Liquid hydrogen tanker obtains only 6 meters draft by cargo weight. Therefore, the ship needs multi-shaft type ship considering propeller immersion. But the single-shaft type ship is also able to be realized by supplying ballast water. And it is also required to make the deeper draft to save the wind pressure area.

In case of twin-hull ship, draft keeping is comparatively easy, because we can arrange cargo tank on the deck and the displacement is small. Because the propel­ler to be multi-shaft too, the optimal ratio of ship type, scale and propeller size will be the theme to be investigated. Considering that there is no need of ballast water,twin-hull ship is thought profitable on the propeller efficiency. But we must sufficient study for the determination of twin-hull ship elements because we don’t have example of large similar ship.

60

For presuming horsepower of liquid hydrogen tanker, there are two methods. One of the methods is to calculate it by presuming the hull resistance from similar ship, one more method is to measure the hull resistance by tank test. In the case of mono-hull ship, presuming from LNG tanker become effective method.

(2) Ensuring the stability and maneuverabilityThe cargo of liquid hydropgen tanker is so light and the breadth of hull be­

comes large. Therefore, the hull has no problem on stability in damaged condition.But became of excessive metacenter hight, it is necessary to sutdy the strength

of tank and the comfort of the crew.For the maneuverability, it is required to establish optimal area of rudder. By

reason of small draft of the mono-hull ship, it is required consideration of using multi-rudder or special rudder for increasing rudder area. And it is required to study the maneuverability in condition of low speed and a strong wind.

(3) General plan of arrangementGeneral plan of arrangement is performed by following process.

CD The concept of cargo containment system is determined, then an outline of ship form and dimensions is determined and we plan the whole of the hull. And we establish the hold length and breadth preliminary.

® We arrange the bow in front of cargo area which has a length considering the resistance efficiency and arrange the engine room in the stern which is able to accommodate the main engine. And we make an outline of conception by settin up propeller at the rear of engine room.

(3) The length-breadth ratio, the breadth-depth ratio and the length depth ratio of a ship show severally the index of the required horsepower, the ability of resto­ration and the longitudinal strength. Therefore, we carry out the preliminary studies of the ratios.

® We calculate the displacement from light ship weight and dead weight. And we imagine the ship type corresponding to ship speed and try to look for a draft from the length and breadth of the ship.

(D Considering a collision, we arrange the cargo tank at a adequate distance from the ship’s sides. And we make the cargo tank to be protected by the hull struc­ture, which is able to absorb large energy of a collision.

© We adjust the outline of the hull by well ballanced arranging of living facili­ties, hydrogen handling equipment, fuel tank, ballast tank and mooring equip­ment.

61

(4) Design of hull structureUp to now, the design techniques of hull structure with three factors of pecu­

liarity, large size and high-speed like a liquid hydrogen tanker has not been estab­lished. The structural design of a ship is commonly studied for the longitudinal strength, the transverse strength and the local strength. But in the case of the liquid hydrogen tanker which is different from common ship, design loads should be determined by tank test in addition to the methods provided in ’’Rule and Regulation for The Construction and Classification”

(5) Selection of main engineOn condition that boil off gas is used for fuel and that the system allows burn­

ing with heavy oil, we compared characteristics for main engines of three types described as follows. And we carried out the plan of engine room for the type of "Hydrogen gas fired boiler/steam turbine”

• Hydrogen gas fired boiler/steam turbine• Hydrogen gas fired gas turbine• Hydrogen gas fired Diesel engine

(6) Design of the tank(D We studied the A5083-O and SUS304 series for using tank material.

• Both the materials slowly increase tensile strength with dropping temperature. And aluminum increases elongation a little with dropping temperature, but stainless steel decreases a little.

• High tensile steel is greatly embrittled by hydrogen in low-temperature. But it is reported that aluminum and austenite stainless steel are not affected by hy­drogen embrittlement. And it is said that hydrogen does not affect the penetra­bility of metal in the liquid hydrogen temperature.

• It is known that the fatigue crack propagation speed of aluminum drops in low- temper atu re( -19 6 "C) and that the fatigue strength of stainless steel drops in room temperature and high pressure(4MPa) hydrogen. It is required that fa­tigue characteristics of metals will be made clear in future.

• Aluminum is corroded by chlorine ion and stainless steel is also corroded in high temperature or damp conditions. But as anticorrosion measures are estab­lished, use in low temperature is not a problem.

© The IGC code, which is applied to design of self-supporting tank loading on LNG carriers, is realized on the concept of ’’Leak Before Failure”. Therefore we try to carry out conceptual design of the liquid hydrogen tanker, based on the design specifications of the LNG tanker. Namely, it is required that we have to assure safety and reliability by the following :

62

• Proof of integrity by fatigue failure analysis• Proof of little crack extention and little quantity of leaked liquid from cracks• Arrangement of equipments to allow safe disposition of leaked liquid

(3) Thermal contraction is larger than in the LNG tank. Therefore, it is required that we must take care of fatigue strength of welded part and must study pro­cessing methods starting with welding.

(7) Tank support ® Spherical tank

The important matter in supporting structure is in adhering tank to hull with­out restraining thermal deformation. Supporting method by cylindrical skirt has satisfactory results for the Moss type LNG tanker. In the case of liquid the hydro­gen tanker, if heat invation from cylindrical skirt becomes a problem, it is able to use low thermal conduction stainless steel in the middle of the skirt.

The method of suspending inner skin by hanger rod has technical issues for connecting structure of cargo tank and rod, and trespass heat.(D Rectangular tank

In the case of the LNG tanker, the cargo tank is only set on the support base at the bottom of the ship. Therefore, horizontal displacement of tank by thermal contraction is not restrained on the support base. Thermal contraction of the liquid hydrogen tank is only larger than in the LNG tank, and the same method will basically be used in both.

(8) Thermal insulation of liquid hydrogen tankBecause liquid hydrogen is ten times more vaporable than LNG, for obtaining

equal boil off rate with LNG, heat insulating material with 1/10 thermal conduc­tivity should be used or the thickness of insulating layer should be 10 times greater. For improving adiabatic capacity, if adiabatic shield cooled by liquid nitrogen is arranged at the middle of the insulating layer, the boil off becomes 1/ 5. If liquid helium or hydrogen is used instead of liquid nitrogen, adiabatic effi­ciency becomes larger. Pearlite vacuum insulation method is used for existing on- land liquid hydrogen spherical tanks. For this method, increasing pack rate of pearlite by vibration and heat hysteresis is problematic. Multi-layer insulating material is best in adiabatic efficiency, but needs high vacuum space.

Fig.5-2 1 shows the plan of adiabatic structure of tank loading on the liquid hydrogen tanker. For obtaining the target of boil off rate(0.2 ^-0.4%/day), the thickness of the insulating layer should be about 50~ 100cm, which does not present a problem in terms of practicality.

63

nitrogen gas vacuum nitrogen gas

rocjm temperature

\ „ y

y.vacugm panel or . multilayer insulant

liquid hydrogen side

rojm temperature

\ B /helium gas or hydrogen gas

m.

PDF or perlite

liquid hydrogen

Outer Shell Inner Shell Tank Skin Outer Shell Inner Shell Tank Skin

Example Example 2Fig. 5-2-1 The plan of adiabatic structure

5.2.3 Test resultsWe worked out general arrangement and midship section drawings for each

tank system as test results. Fig.5-2-2 and Fig.5-2-3 show general arrangement and midship section drawings for spherrical and rectragular types in the case of the mono-hull ship.

5.2.4 Future research directions and tasksWe classified issues resulted from the above studies into the following catego­

ries; design issues, issues requiring experiments, and issues to be taken up by other sub-task. The following results have been obtained from these efforts:

(1) We have confirmed that technologies on the extension of the existing technolo­gies can be used for general feature technologies (arrangement plan, stability, hull construction, etc.) of the ship. However, the feature technologies of the large-sized twin hull ship requires further studies.

(2) The basic concept to ensure safety in tank design has been defined. We have confirmed it necessary to establish the design philosophy on the liquid hydro­gen tanker including the tank. 3

(3) We have confirmed it necessary to develop new technologies beyond the cur­rent technological level; for example, the tank thermal insulation method will require thermal insulation performance 10 times of that of the LNG tank. We have proposed concrete thermal insulation methods this fiscal year; panel insu­lation plus vacuum space method, and thermal insulating material(PUF) with gas backup.

64

Ship type : Mono-hull ship Tank capacity : 200,000m3Tank system : Double skin spherical 4-tank system

Overall length 335mLength between perpendiculars 320m Breadth(molded) 55mDepth(molded) 31mSummer load line(molded) 10m

Main engine : Hydrogen gas fired boiler/steam turbine Approx. 40,000PS x 2 unit

Propel equipment : Propeller (twin shaft)Ship speed : Approx. 25 knots

VACUUM SPACE

N? SPACE

TANK COVER

OUTER SKIN

fcd §

Midship Section

General Arrangement of Liquid Hydrogenn Tanker

Fig.5-2-2 Mono-hull ship loading spherical tank

65

Ship type : Mono-hull ship Tank capacity : 200,000m3 Tank system : SPB 2-tank system

Overall length 310mLength between perpendiculars 288m Breadth(molded) 48mDepth(molded) 21.4mSummer load line(molded) 10m

Main engine : Hydrogen gas fired boiler /steam turbine Approx. 40,OOOPS x 2 unit

Propel equipment : Propeller (twin shaft) Ship speed : Approx. 25 knots

; TANK DOME

. N, SPACE

VACUUM SPACE

PANEL INSULATION

/ Q

L.W1.

—in------gr

Midship Section

—------ ~---------------------------------- ---------------- i------------- ppIHMWIIDJWMmiUWWaWW LV"MWM^V.WMMMUMMUMUV4| “

111 --- LHZ tank - "" ff """. . . LH2 tank;!|—10CX OOQdi3:-:-——... . -.-.-.ylOO, OOQmV.:——

W »/.\\\WAW.>rAWdVs\%v 5-

=D

CD

l

General Arrangement of Liquid Hydrogenn Tanker

Fig.5-2-3 Mono-hull ship loading rectangular tank

(4) It has been confirmed that the same method as that of the LNG carrier is applicable basically to the tank support method.However, impact on the intruding heat, measures against thermal shrinkage, connections with the insulation material and related details have been con­firmed to remain as major issues to be solved in future.

(5) It has been confirmed that the same method as that of the LNG carrier is applicable basically to the dome structure. It has also been confirmed that the impact of cryogenic temperature and others require detailed studies.

(6) Development of the main engine using hydrogen fuel as well as development of tank material and common equipment have been confirmed to require making an effective use of the study results of other sub-task and other fields. Table5-2-2 summarizes the issues discussed above.

67

Table 5-2-2

Study item Issue Correspondence

Estimation technologies of

ship type and horse power

Monotype-hull ship : Measures against small draft (ensuring

draft, propeller efficiency, rudder)

T\vin hull ship : Design of the optimum ship type

Study on the extension

of the existing design

technologies

Ensuring the stability and

maneuverability

Impact of increase in wind area on propeller efficiency

General arrangement plan Optimum arrangement plan

Hull construction design

technology

Design load calculation method of high speed ship

Strength of the connection between hulls of twin hull ship

(Tank test)

(Structure analysis)

Selection of main engine

and auxiliary engine

Development of hydrogen fired boiler, steam turbine hydrogen

fuel gas turbine and hydrogen fired diesel engine of about

40.000 to 50,000 PS

Waiting for study in

other fields

Development of fuel battery (auxiliary equipment)

Tank design Characteristics of tank material (aluminum. SUS) in the liquid

hydrogen (brittleness, fatigue strength and hydrogen infiltra­

tion on weld zones)

Request the study to

be made by Sub-task 6

Establishment of design philosophy with consideration given to

safety

Design study

Tank support method Study of strength

Measures against heat from the support

Structure of the connection with thermal insulation material

Measures against thermal shrinkage of the tank

Study of experiment

and design

Tank thermal insulation

method

Confirmation of each thermal insulation method

Follow-up characteristics of thermal insulation material

according to tank deformation

Creation and maintenance of highly vacuum space

Experiment and design

study (in corporation

with Sub-task 5-3)

Dome and its surrounding

equipment

Dome : Follow-up characteristics according to tank thermal

shrinkage

Ensuring the strength for vacuum

Measures against heat

Experiment and design

study

Piping : Development of vacuum double piping

Others : Measures against safety value freezing

Development of level gauge, flowmeter, pressure gauge,

thermometer and strain gauge for liquid hydrogen tank

Request the study to

be made by Sub-task 6

68

5.3 Development of the liquidhydrogen storage storage facilityDevelopment of the the liquid hydrogen storage equipment can be broadly clas­

sified into two phases ; design of the total system for storage equipment and research of the storage equipment. To study the current technologies in the cur­rent fiscal year (1994) according to "design of the total system for storage equip­ment” phase, we studied the following items ; (l)similar large liquid storage sys­tem, (2)existing liquid hydrogen storage equipment, (3)peripheral technologies for in-ground storage tank and (4)underground bedrock storage tank. To study the basic system flow, initial study of the system was made on the large storage system. To study material and structure of thermal insulation in the "research of the storage equipment” phase, study was on (l)similar large cryogenic storage tank, (2)existing liquid hydrogen storage tank and (3)related documents. Initial study of the conceptual design was made on four types of thermal insulation structure. The following describes the outline of these studies.

5-3-1 Design of the total system for storage equipment

A. Study of current technologies

(1) Study of similar large liquid storage system.Storage system was studied last year on LNG receiving terminals in Japan.

Placing the study target on overseas LNG receiving terminals this year, we stud­ied the loading equipment, vaporization equipment, BOG disposal equipment, BOG reliquefaction equipment, return gas equipment, exhaust gas disposal equipment, safety equipment, and inert gas production equipment.

Based on these research results, we worked out the typical plant flow and equipment layout of each plant, thereby providing reference information on liquid hydrogen storage plant.

Comparison of these study results with the terminals in Japan has revealed two characteristics ; l)a greater number of BOG reliquefaction equipment are in­stalled, and 2)gas is returned to the LNG carrier by the storage tank pressure in some terminals when LNG is received from the LNG carrier. It has also shown that there is no difference in other equipment.

We picked up the tasks to be studied when they are applied to the liquid hydro­gen storage equipment. Since the temperature is lower than that of LNG, a great number of equipment(loading arm, vaporization equipment, cryogenic compres­sor, hydrogen pump, etc.) must be developed.

(2) Research of existing liquid hydrogen storage equipment.

69

The existing liquid hydrogen storage equipment uses the gas pressure feed system to feed the tank liquid from the storage ; therefore, the design tank pres­sure of 5 or 7kg/cm2 is used in may cases. The tanks of this type have increased plate thickness both in Japan and abroad. When consideration is given to material, processing, and X-rays at the site, the maximum practical plate thickness is 50mm. Accordingly, the maximum capacity is 16,000m3 when the internal pres­sure is assumed as Skg/cnf.

(3) Research of peripheral technologies for in-ground storage tank.The in-ground storage tank features highly earthquake proof design, as well as

safety in the protection against liquid leakage. The in-ground storage tank is more advantageous for the storage of a amount of liquid hydrogen in order to ensure cryogenic properties as well as security and safety.

In fiscal 1993, we studied the documents on cryogenic properties of concrete, reinforcing bars and reinforced concrete as component members of the storage structure, and frozen soil control, especially thermal property of the ground and frozen soil characteristics. In fiscal 1994, study was made on the achievements gained both in Japan and abroad regarding the structural component members of the LNG in-ground storage equipment and control of the frozen soil surrounding the storage area, in order to provide basic data on the applicability to liquid hydrogen storage.

The result of the study has revealed that a minimum temperature of — IGO'C is assumed for the cryogenic properties of reinforced and prestressed concrete and their components, concrete, reinforced bar and prestress steel. To ensure satisfac­tory performances against possible liquid leakage in the event of earthquake, it is necessary to comfirm cryogenic properties on the —250*0 level for reinforced and prestressed concrete component members.

Furthermore, the freezing method based on cryogenic properties of the frozen soil is utilized in underground construction works, and its effect has already been demonstrated. The in-ground storage tank requires freezing control and manage­ment. Research and development required for the development of the liquid hy­drogen in ground storage tank includes ljresearch and development of the ex­periment equipment, measuring technique and experiment know how for use at the temperature of — 250“C, 2)improvement of the concrete structure members and development of new material, 3)experimental studies on freezing properties of soft rock and hard rock, and 4)study of expanding the scope of using the frozen soil.

(4) Study of bedrock storage tank

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To obtain information on the conceptual design of the underground liquid hy­drogen bedrock storage system, we continued the document studies of fiscal 1993 on underground cryogenic liquid gas storage,and mechanical and thermal proper­ties.

The current conditions of underground cryogenic liquid gas storage are as fol­lows : underground LNG storage test has been successful in the clay layer, and commercial use of the underground LNG storage in the bedrock is already started. However, there is no record of having succeeded with LNG. This is because bedrock shrinks when it is cooled, causing cracks in the bedrock ; LNG enters these cracks resulting in generation of a great amount of boil off gas. To prevent this, Sweden and other countries are studying thermal insulation material and grout curtain. Since there is no extensive clay layer Japan, bedrock should be considered as the ground where the liquid hydrogen storage facility are to be constructed

For the cryogenic properties of the rock, underground LNG storage is the target for the time being, so study has been made down to a minimum temperature of — 180°C. However, no research has been made in the temperature range below this limit. Accordingly, clarification of the cryogenic properties of the rock in the liquid hydrogen temperature range can be said to be one of major tasks for re­search and development.

B. Study of basic process flow for a great amount of liquid hydrogen storage.

To configure the system flow of the liquid hydrogen storage equipment, we estimated on the storage plant size and basic process flow.

The following studies have been made on two types of plants ; ®the storage plant adjacent to the hydrogen liquefaction plant and ©storage plant adjacent to the power plant:

• Study was made on interfaces among the hydrogen liquefied plant, power plant and hydrogen tanker, thereby setting up the storage plant size and conditions for the study.

• An approximate plant layout was assumed.• Thermal and material balance tables of the overall plant were worked out un­

der these conditions.• Functions of each unit constituting the storage plant were defined.• The capacity of each unit was set up according to the result of studying the

thermal and material balance.Our study project for the next fiscal year is to continue to follow the interface

71

conditions in conformity to the progress in other sub-tasks, to develop the basic flow of the storage plant into flow for each unit, and to study individual unique detailed specifications.

5-3-2 Research of the storage equipment

A. Thermal insulation material and structure.

(1) Study of the types of similar large cryogenic storage tanks and thermal insula­tion structure.We used questionnaire formats and documents to study the similar large cryo­

genic storage tanks such as aboveground storage tank, cryogenic in-ground stor­age tank, and superconducting magnetic energy storage thermal insulation struc­tures. Following the study of the thermal insulation structure of the general sec­tion conducted in the proevious year, study was made on the thermal insulation structure of the penetrations(nozzles) and tank internal fixed sections(anchors) of aboveground storage tank and cryogenic in-ground storage tank this year. The nozzles of the LNG aboveground storage tank is supported by the internal tank to ensure strength, while the interface(connections) with the external tank uses the bellows to ensure sealing properties. The thermal insulation material mainly uses glass wool to absorb the nozzle deformation.

The LNG in-ground storage tank nozzle is supported by the external tank roof. The thermal insulation material uses rigid urethane foams. The cold reserving structure of the LNG in-ground storage tank corner is closely related to the mem­brane structure ; therefore, it is classified according to the membrane type.

Since a great force is applied to the lower support of the pump barrel of the LNG in-ground storage tank, the structure of anchoring directly to the concrete body is used.

These studies have provided general information on the types and thermal in­sulation structures of the similar large liquid storage tanks. Application of the thermal insulation structure for LNG directly to the liquid hydrogen is difficult, and it is important to make efforts on the study and research of the thermal insulation structure for the fluid having a temperature below that of liquid hy­drogen. 2

(2) Study of the experience of using the existing liquid hydrogen storage tank.In the previous year, we used questionnaire formats and documents to study

the general outline on the experience of using liquid hydrogen storage tanks with a greater capacity, and the thermal insulation structure. The result of the study

72

has revealed that the greatest capacity of the existing liquid hydrogen storage tank in Japan is 540m3 at the Tanegashima Space Center, outside Japan, 3,218m3 at J.F. Kennedy Space Center of NASA, the largest tank with perlite vacuum insu­lation in the world.

As a result, the perlite vacuum insulated storage tank is used in the large stor­age tank because of its freedom in the site area, relatively stable insulation perfor­mance and excellent workability. On the one hand, the multilayer vacuum insu­lated storage tank is used in the smaller storage tank bacause of its capability of making an effective use of storage tank space and minimizing the thermal insula­tion and heat capacity. To prevent the thermal insulation material from avsorbing moisture, they adopt the method of direct charging of the thermal insulation material(perlite) into the thermal insulation layer to ensure a high vacuum, or the thermal insulation process(insulation of the multilayer insulation on the storage tank) in the air-conditioned room.However, the large liquid hydrogen storage sys­tem planned in the WE NET requires development of feature technologies such as thermal insulation support structure of the internal tank(liquid storage), in addi­tion to the experience with these thermal insulation.

(3) Study of documents on thermal insulation material and thermal insulationstructureTo get a deeper insight into the thermal insulation technologies having been

researched and developed so far and to make an effective use of them for the development of large and medium-sized liquid hydrogen storage tanks, we studied the documents on thermal insulation material and thermal insulation structure in low-temperature and cryogenic fields.

In fiscal 1993 and 1994, study was made on the material and structure of the non-vacuum insulation, vacuum powder insulation, multilyaer insulation, other vacuum insulations, and thermal insulation support members. At the same time, the performance test apparatus for the thermal insulation material and thermal insulation structure in the current research and development project were also studied in fiscal 1994.

As a result, we could get an approximate picture of the performances at the temperature of 20K regarding the heat conduction and mechanical strength of the thermal insulation material and support material used in many thermal insulation methods. At the same time, we obtained much information on thermal insulation structure and support structure. We could also get a clear picture of various test apparatus mainly to obtain thermal properties such as heat conduction rate, as performance test apparatus for thermal insulation material and thermal insula­tion structure. However, almost no large on-land storage tank is included as an

73

object of research in general. Most of the research projects are related to space such as liquid hydrogen rocket and superconductive cryostat. Accordingly, this must be taken in account carefully in making reference to the documents studied for the development of large and medium sized liquid hydrogen storage tanks.

The results of the study have been described in summaries for each document studied. For the report, the information obtained during the period of fiscal 1993 and 1994 will be described in the form of a report according to the classification.

B. Conceptual report

Based on the interface conditions, the internal capacity of the storage tank was set to 50,000kl, storage pressure to 0.2kg/cnfG, and thermal insulation perfor­mance to 0.1% per day(as a target), which is equivalent to about the same as that of the LNG. Under these conditions, storage types were classified, with major emphasis placed on thermal insulation structure, and the companies in charge were determined ; thus the conceptual design was worked out, and technological tanks were picked up.

(1) Type 1We worked out conceptual design of the spherical tank and aboveground stor­

age tank(flat bottomed cylindrical tank) using the vacuum powder insulation. The micro-sphere having a loading capacity was used as the bottom insulation mate­rial of the aboveground storage tank(flat bottomed cylindrical tank). This mate­rial requires confirmation in the future experiment because of lack of design data 2 3

(2) Type 2We worked out the conceptual design of the aboveground storage tank(flat-

bottomed cylindrical tank) based on the vacuum insulation method using the solid insulation. Since thermal insulation performances greater than those of the LNG by one digit are required, we studied the characteristics of the current thermal insulation material. Based on the result of this study, we devised a new thermal insulation structure and obtained thermal insulation performances.

Firstly, we studied the parameter of the storage shape which would minimize the heat intrusion, thereby calculating the optimum dimensions.

To achieve the initial target of 0.1 percent per day regarding the most impor­tant thermal insulation structure, we studied the following :CD Form insulation(urethane) plus vacuum thermal insulation material ® Urethane surface covered with metallic membrane(3) Thermal insulation by vacuum panel

74

Then the characteristics and issues of each method were picked up.Furthermore, in order to improve the thermal insulation performance, we de­

vised the method of using the thermal insulation shield, and made thermal analy­sis. We have confirmed that substantial improvement of the performance is pos­sible. The future task is to evaluate the above mentioned thermal insulation meth­ods and to find out the optimum method in combination with the storage tank structure.

(3) Type 3Conceptual design of membrane type large liquid hydrogen storage tank was

worked out as one type of the large liquid hydrogen storage tank. Two types of thermal insulation were considered ; vacuum thermal insulation and non-vacuum thermal insulation. The membrane is a stainless type thin film maintaining liquid and air tightness while absorbing thermal shrinkage, and is mainly used in the LNG in-ground storage tank. We clarified the design conditions for the membrane and strength evaluation method when applied to the liquid hydrogen storage tank.

In the vacuum insulation, multilayer insulation was adopted, and GFRP(glass fiber reinforced plastic)made cylindrical support column was used as thermal insulation support material. BOG generation rate was 0.093% per day for 180 layers having a thickness of 650mm.

The non-vacuum insulation type uses the normal-pressure PUF(polyurethane foam) as thermal insulation material and support material. PUF had nitrogen charged into the normal-temperature side and helium into the low-temperature side. Furthermore, membranes were provided between two layers to ensure he­lium gas tightness. The helium filled PUF was 2,500mm thick and nitrogen filled PUF was 3,900mm thick, with BOG genaration rate exhibiting 0.099% per day.

Tasks as common items included sealing property of the membrane, strength at the cryogenic temperature, the thermal insulation performance of the multilayer material for vacuum insulated storage tank, workability, vacuum making method, thermal insulation performance of the helium filled PUF for non- vacuum insu­lated storage tank, helium gas replacement method and impact of PUF creep.

(4) Type 4We worked out the conceptual design of the aboveground storage tank(flat

bottomed cylindrical tank) and spherical tank based on non-vacuum insulation using the powder insulation material. In order to ensure the required thermal insulation performance with the realistic thermal insulation thickness, shields were provided in the thermal insulation space. Study was made on the enclosed shield type and open shield type.

75

The parameter of thermal insulation thickness was studied for each type of each storage tanks and shields, to get up the optimum dimensions. We could get the dimensions which could be realized from the viewpoint of storage tank strength. However, the insulation thickness had to be made much larger than those of other vacuum insulation methods.

Because of non-vacuum insulation, only helium gas can be used as gas to be filled into the thermal insulation space in order to ensure that gas on the side in contact with the internal tank does not liquefied at the liquid hydrogen tempera­ture. However, the enclosed shield type has an advantage in that nitrogen gas can be used in the thermal insulation space on the outer side. Such characteristics and tasks were picked up.

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5.4 Development of devices for commom useThe research group carried out investigation of the following four urgent

themes for the second year running in the work of "Development of Devices for Common Use”of the development of hydrogen transportation and storage technol­ogy according tothe WE-NET Working Plan in 1994. The technology is a theme of subtask 5.

- Large liquid hydrogen pumps• Vacuum adiabatic piping of large diameter• Liquid hydrogen valves• Instrumentations

First, the investigetion was started with examination of the previous tech­niques to review the current technical level. With the results and along the com­ing study policy, the research group carried out conceptual designs of the compo­nents of the four themes and technical investigation needed for the design works.

5.4.1 large liquid hydrogen pumpsThe large liquid hydrogen pumps investigated for use in the WE NET Working

Plan is to serve to transport liquid hydrogen to a hydrogen liquefying facility, tanker, and other various places. Basic specifications and structures of the pumps, as shown in Fig.5-4-1, are decided with respect to an aspect of perfor­mance characteristics as a high-capacity pumps, environmental aspects of treat­ing the liquid hydrogen of combustible and explosive cryogenic fluid, and service­able aspects of operationability and maintenability.

.Performance,

Large capacity pump High revolutionpump

Large liquid hydrogen pump

Low-temperatureembrittlement

Simple structure Easy startability Safety /

Hydrogenembrittlement

ironment

Fig.5-4-1 Factors required for the large liquid hydrogen pumps

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Of the large liquid hydrogen pumps, the research group carried out investiga­tions, including types of pump to develop a high and low pressure transport pumps chiefly, the low NPSH that is a basic element technique of the pumps along with motors, and bearings. The group also investigated the elements with respect to actual conceptual designs to make clear problems of the high-capacity pumps. The group found from the investigations that the problems must be clarified in detail through further element development in future.

Last year, the research group examined the previous techniques for the pumps before having investigated their concepts. This year, on the basics of the results, the group carried out quantitative investigation of achievability of the liquid hy­drogen pump according to the basic specifications of the pump worked out in the investigation of system to obtain the possibility.

As a result of the examination and investigation, the research group found that it would be possible to design and manufacture the liquid hydrogen pump of simple structure having high characteristic performance, durability, and safe per­formance on the basis of a vertical axis wet air pump having an axial-flow pump or mixed flow pump connected directly with a wound rotor induction motor.

5.4.2 Adiabatic pipingAs to the adiabatic piping that is indispensable as common arrangement for

transporting liquid hydrogen, the research group carried out the following techni­cal surveys of it as the surveys in continuation of the last year. The surveys were about thermal expansion and contraction mechanism of the cryogenic piping, joint structure of adiabatic piping, and adiabatic piping at an LNG base.

• Thermal expansion and contraction mechanism :Survey of the present techniques of measures for thermal stress due to

cryogenic expansion and contraction absorbing mechanism, for the cryogenic piping of long distance and large diameter.

• Joint structure :Survey of the joint used at an umbilical point of the H II rocket as a similar

existing joint technique in connection with development of the joint structure of loading arm needed to load in and unload out of a tanker the liquid hydrogen.

• LNG base :Survey of scales and operational techniques of the unloading piping of existing

LNG bases that are relatively similar to the final scale and system configuration of the liquid hydrogen storage base of the WE-NET Working Plan.

Also, the research group carried out the following fundamental survey and investigation of basic dimensions and weights,adiabatic structure, thermal expan­sion and contraction structure, and joint structure of the adiabatic piping in con­

78

nection with the apparatus development that was a study theme beginning with this year.

- Basic dimensions and weights :Interface conditions among the facilities were arranged for estimating scale of

the base to decide conditions required for the adiabatic piping to decide desired development values, such as opening diameter and piping length, of the adiabatic piping for liquid hydrogen.

• Adiabatic structure :Selection of the adiabatic structure for liquid hydrogen piping was investigated

by classifying adiabatic methods for cryogenic piping.• Thermal expansion and contraction structure :

Comparison investigation was made on thermal expansion and contraction structures for relaxing thermal stress due to thermal expansion and contraction of pipe material caused by external air temperature and cryogenic internal fluid.

• Joint structure :Preliminary survey was made as to amount of adsorption gas since the gas was

adversely adsorbed and accumulated in piping at the liquid hydrogen temperature when the coupling joint of loading arm was mounted and removed frequently.

As a result of the survey of vacuum adiabatic piping of large diameter, it was found that for the piping technique for transporting large amount of cryogenic LHgStably and safely, it is needed to combine selectively a shield built-in multi­layer adiabatic structure to be used as adiabatic structures, self-bending of pip­ing, method of bellows expansion and contraction joint, and hinge/gimbal type in addition to the vacuum adiabatic piping technique accumulated up to the present, depending on requirements, including diameter, heat entrance limit, and design pressure.

As a result of the preliminaly survey of the amount of adsorption gas at the liquid hydrogen, it was found that the joint structure had to be subjected to a treatment to decrease the adsorption if the joint was made to contact air as being removed and mounted repeatedly.

The research group is scheduled to investigate the basic design of the structure in detail from the next year on the basis of the above-described results obtained by the survey and investigation in this year. The group also intends to decide test methods items that have to be checked by element tests.

5.4.3 Liquid Hydrogen ValvesThe research group carried out survey of the existing techniques before having

investigated the techniques needed to develop the actual liquid hydrogen valves.In the investigation, the group made up tentative specifications of the liq­

79

uid hydrogen valves likely needed in the assumed system, evaluated the optional individual techniques and while selecting appropriate techniques, decided the fi­nal details of the arrangements. In particular, the group carried out investigation of the following items in detail since they would be key points in development of the arrangements.

(1) Materials(2) Flow characteristics(3) Valve drive mechanism(4) Seal

For the system assumed for designing and fabricating the liquid hydrogen valve, it was estimated that two types of remote-control valves were needed broadly. One included glove halve of pneumatic operation, and the other was but­terfly valves ofpneumatic operation. The existing valves of both types were not large enough to use in the assumed system. Even the present largest valves are for the rocket test facility, but far larger ones are needed in use for the system.

One of the most important technical problems in developing the liquid hydrogenvalves is the one associated with the large size in the element technique. Desk work is limited to the problem. The research group hopes that element tests shouldbe started to confirm that the techniques of liquid hydrogen valves investigatedhere can appropriately reflect on the actual ones.

5.4.4 InstrumentationInstrumentation technique is indispensable for treating large amount of

hydrogenin the WE NET Working Plan. In this year, continuing from the last year, the research group investigated types of liquid level gauge and flow meter and method of leakage detection as to their conceptual design, particularly in their technical problems and items to be solved.

For the types of liquid level gauge, the group surveyed an ultrasonic liquid level gauge type, electrostatic capacity type, and pulse reflection type. For the pulse reflection type promising of them, the group carried out its conceptual de­sign so that it can undergo a developed element test in future.

For the methods of flow measurement, the research group carried out surveillanceof the previous techniques and investigation of technical problems separately for each of objects of measuring dealings, designating an operating point in the system,and detecting little leakage. On the basis of a result, of the flow meters, the group investigated a turbine flow meter, Coriolis flow meter, and volu­metric flow meter particularly in their features and development items. Of the

80

leakage detection types, the group investigated a contact combustion type, semi­conductor type, gas thermal conduction type, and infrared absorption type, thereby having clarified their features and problems to use.

As a result, the above-mentioned methods were not always used for any of the applications. They have to be used selectively depending on necessity. As for the elements to be developed for the large scale, it was made clear that they should be confirmed as soon as possible.

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5.5 Development of hydrogen absorbing alloys for small scale transportation and storage system

Hydrogen storage alloys which reversibly absorb and desorb large amounts of hydrogen have the following characteristics as a medium for transport and stor­age of hydrogen,

• Large hydrogen-packing densities(more than 1,000 times in volume and 1% in weight).

• Easy handling without the use of high pressure vessels or adiabatic ones.' Safe operation under moderate conditions and almost free from explosion.• Good compatibility with environments because of simple hydriding and

dehydriding reactions with nontoxic alloys.• Stable storage without hydrogen losses for a long term.• Relatively rapid charge and discharge rates of hydrogen.• Considerably good durability of the alloy.• Various alloys and their controllable properties.

In this year, applicabilities of the alloys(metal hydrides) to hydrogen storage uses in International clean Energy Network Using Hydrogen Conversion have been preliminarily examined in order to clarify the rationale for R&D activities in SubtaskS 5. The applications investigated are as follows,

• Portable hydrogen storage containers.• Stationary hydrogen storage units for dispersive consumers.• Hydrogen fuel tanks for motor vehicles.- Storage and compression units of boil off hydrogen in a plant composed of

hydrogen combustion turbines and liquid hydrogen tanks.In addition, production methods of magnesium alloys and hydrogenation prop­

erties of nanocrystalline hydrides have been studied in international collabora­tion with Canadian institute as a part of surveys on the present R&D status of hydrogen storage alloys. R&D activities of hydrogen energy systems and metal hydrides in foreign countries were also investigated by attending the Fall Meeting of the Electrochemicals Society and visiting research facilities in USA., Germany and Spain.

5.5.1 Survey of hydrogen storage alloys(1) Production methods of magnesium alloys

Magnesium alloys are produced by melting methods using additive fluxes or cover gases such as SF3 in refineries. The casting processes, conditions and appa­ratuses were surveyed. The melting method using SFg as cover gas will be appli­cable to the industrial production of Mg based hydrogen storage alloys, although

82

the casting processes have to be modified becase of a volatile nature of melted magnesium. Other casting methods of magnesium alloys such as sintering and mechanical alloying were also surveyed. Finally, preparation methods of Mg- based hydrogen storage alloy samples were reviewed with respect to LaMgbased ternary alloys by melting, a Mg2Ni intermetallic compound by sintering,and amor­phous Mg-Ni based alloys by mechanical alloying.

(2) Nanocrystalline metal hydridesNanocrystalline alloys are defined as material with nano-scale grains, typi­

cally 50 nm or less. The alloys are known to exhibit unusual mechanical and chemical properties. Metallographic and hydriding properties of nanocrystalline FeTi, Mg2Ni and LaNi5 alloys prepared by ball-milling have been reported. They show hydriding characteristics superior to those of conventional crystalline FeTi, Mg2Ni and LaNi5. Especially, activation becomes much easier and resistance to air is much improved. The hydriding characteristics are further improved by addi­tion of a small amount of Pd as ahydrogenation catalyst. The catalyzed materials show substantially enhanced hydrogenation kinetics and are much less sensitive to air exposure. The nanocrystalline alloys have advantages of mitigation of acti­vation treatments and handling without too much care about the protection against air and humidity.

5.5.2 Examination on applicabilities of hydrogen storage alloy tohydrogen transport and storage systems

(1) Portable hydrogen storage containers.First, hydride storage units developed up to date were surveyed on design

parameters(hydrogen storage capacity, operating temperature, absorption pres­sure, alloy composition, heat exchanging method).

Next, specifications and operating charasteristics of a portable hydride storage container developed by Japnese Company was introduced.

Small portable hydride storage units are commercially available as a hydrogen generator and a hydrogen tank for fuel cells. Most of the portable hydride units are fabricated with small and simple alloy containers and are operated with exter­nal air heat exchange. Although the portable units have volumetric and safe ad­vantages over compressed hydrogen cylinders, the commercialization has not made progress yet. Reduction in price and weight is required in order to enlarge their demands in various uses for transporting and storing hydrogen.

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(2) Stationary hydrogen storage unitsApplicability of matal hydrides to stationary hydrogen storage systems at re­

mote areas where liquid hydrogen is transported by trailers and freight trains has been examined in comparison with that of gaseous or liquid hydrogen. Gas­eous hydrogen storage methods have volumetric and safe disadvantages and ap­pear to be unsuited for stationary hydrogen storage units for dispersive consum­ers, especially for home and town uses. It is advisable to utilize liquid hydrogen tanks delivered by trailers and freight trains as hydrogen storage units for hydro­gen storage facilities where boil off hydrogen discharged from the tanks is effec­tively consumed. However, liquid hydrogen storage methods are not always suit­able for consumers who use relatively small amounts of hydrogen variably and intermittently, because boil off hydrogen is continuously liberated throughout a storage term and supplementary means to use it efficiently and to handle it safely are required in addition to liquid hydrogen tanks. It is considered that hydride storage methods are useful for consumers who use hydrogen in intermittent and variable manners hourly and seasonally and are highly applicable to stationary hydrogen storage units for individual houses located dispersively at remote ar­eas.

Although stationary hydrogen storage units using metal hydrides have the dis­advantage of a relatively high cost, they have the advantages of a large hydrogen packing density, an easy and safe handling and a stable long term storage over gaseous and liquid hydrogen storage units. For their widespread use, economical improvement is essentially by exploring cheap hydrogen storage alloys less than ¥ 100/kg. The alloys with hydrogen absorption capacities more than 1.6 wt% and the hydrogen storage capacities of about 300Nm3/m3 are also desired to be devel­oped.

(3) Hydrogen fuel tanks for motor vehiclesLiterature surveys on hydrogen fueled vehicles and their hydride fuel tanks

have revealed that most of the prototype vehicles using the hydride tank are satisfactory to a certain degree in driving performances. Applicability of the hydride tanks to the vehicles has been investigated from the point of view of safety, convenience and economics. It can be said that the hydride tanks are satis­fied with laws and regulations for automobiles and dangerous things in Japan,because they are capable of storing hydrogen at pressures less than IMPa and without its leakage and are sufficiently protective against firing and explo­sion in traffic accidents. The most important research issue for the tank is elonga­tion of a running distance per hydrogen charge. Hydrogen storage alloys capable of absorbing hydrogen at a ratio of about 3wt% and desorbing it below 100X3 are

84

desired to be developed. Reduction of the tank cost, shorting of refueling time and accurate measuring method of retained hydrogen capacity are also important re­search issues.

(4) Storage and compression units of boil off hydrogenIn a l,000MW class power generation plant composed of hydrogen combustion

turbines with an electric power conversion efficiency of 60% and liquid hydrogen tanks with a storing scale of a 30-day consumption amount, supplementary hydro­gen storage facilities with a capacity of more than lOOkNm3 are estimated to be required to capture a huge amount of boil off hydrogen discharged from liquid hydrogen tanks and flashed during transfer operations of liquid hydrogen from its tanker to tanks.

Hydrogen storage alloys absorb hydrogen at low temperatures and pressures, and desorb it at high temperatures and high pressures. This characteristic enableas a hydride container to function as not only a hydrogen storage unit but also a compressor. Hydrogen discharge pressures can be also elevated in a way of multi stage absorption desorption repetition by a combination of the containers filled with the alloys with different equilibrium hydrogen pressures in a range of temperature. For example, it is possible to elevate hydrogen pressure from 0.1 to 5 MPa in the three stage repetition at two temperature of 20 and 80 °C. In addition,the hydride storage units allow to store gaseous hydrogen compactly, 1/ 300 in volume ratio between the unit and atmospheric pressure hydrogen. There­fore, hydrogen storage alloys are considered to be applicable to storage and compression units to capture boil off hydrogen and to supply it for hydrogen combustion turbines. For stationary hydride storage units and vehicular hydride fuel tanks,the relatively small number of hydrogen absorption and desorption times results in the increase of hydrogen storage costs. However, the hydride storage and compression units in the plant can be operated in a 12-hour inter­vale-hour absorption, 6-hour desorption) or less, the number of the absorption and desorption times exceeds 14,000 in 20 years, bringing about the consider­able decrease of the hydrogen storage cost per cycle. Warm waste heat to dis­charge hydrogen will be available from hydrogen combustion turbines. Further­more, the use of the hydride storage compression units makes it possible to elimi­nate some hydrogen compressors for storing boil off hydrogen in its gaseous state and supplying it for the turbines.

Feasibility studies to make use of hydride storage and compression units in the plant are planned to be performed in the succeeding years.

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5.5.3 On-site surveys on R&D activities of hydrogen energy systems and hydrogen storage alloys in foreign countries

(1) Fall meeting of the electrochemical societyHydrogen and Metal Hydride Batteries Symposium was held in the meeting.

Thirty seven presentations in the symposium ranged from fundamental studies such as characterization of hydrogen storage alloy and elucidation multi-compo­nent effects to applied ones such as performance tests of Ni MH batteries, recy­cling of the alloys and so on. Commercialization of Ni MH batteries have brought a large progress in R&D of the alloys.

(2) ERGENICS Inc.Ergenics Inc. is a pioneer in various applications of hydrogen storage alloys

and manufactures hydride storage units. Information was exchanged on R&D ac­tivities ofthe alloys.

(3) Institute National De Tecnica Aerospecial(INTA)Operating tests of a hydrogen production and storage system are performed.

The system is composed of a photovoltaic equipment(8.5kW), an alkaline water electrolyzer(5.2kW), a hydride storage tank(24Nm3) and a compressed hydrogen storage vessel.

(4) Gesellschalt Fur Elektrometallurgie MBH(GFE)GFE manufactures and sells various kinds of hydrogen storage alloys and hy­

dride storage units with a hydrogen capacity from 1 to 100 Nm3. The company has shown a high capability of both developing and manufacturing the alloys and the hydride units.

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6. SubtaskG: Development of cryogenic materials technology

6.1 R&D goalsThis R&D project aims at developing low temperature materials that are used

in hydrogen liquefaction, transportation, and storage facilities. While working to develop structural materials which can be used under liquid hydrogen conditions and appropriate welding methods for them, we also attempt to identify conditions which these materials require for hydrogen transportation and storage technol- ogy.

Three existing materials which can be applied for liquid hydrogen storage tanks or tankers were selected for evaluation test at liquid helium temperature(4K) and room temperature(RT). The materials were two austenitic(y ) stainless steels, SUS304L and SUS316L which had been already used for liquid helium circumstance and a non-heat-treatable aluminum alloy, A5083, which had been frequently used as structural materials for LNG tankers. Welded joints of each materials were made and test specimens were taken from base metal, weld metal and heat-affected zone(HAZ). Some of specimens were hydrogen charged before the testing for evaluating susceptibility to hydrogen embrittlement. In addition, tensile and fatigue test in high pressure hydrogen gas atomosphere were conducted at RT.

25mm thick plates of the three materials were used. Welded joints were made by Tungsten Inert-gas arc welding (TIG) for the stainless steels, and by Metal Inert-gas arc welding (MIG) for the aluminum alloy. All of test specimens were extracted from the center of thickness of the plates. Hydrogen charging treatment was performed in high temperature, high-pressure hydrogen gas atmosphere. Hy­drogen contents after the charging was about 30ppm for stainless steels and about O.OSppm for A5083.

Table.61 shows the summary of evaluation result on susceptibility to low temperature embrittlement and to embrittlement of weldment of specimens with­out the hydrogen charging by comparing the testing value of each specimen with those of base metal at RT.

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Table 6-1 Summary of low temperature embrittlement and embrittlement of weldment of specimens without hydrogen charging

Properties

Position

Tensi1e strength

Elongation •Reduction

of area

Charpyabsorbed

energy

Fracture toughness

( J I c )

Fatigue1 i f e

(In air)

Materials RT 4 K RT 4 K RT 4 K RT 4 K RT 4 K

S 3 0 4 L Base metal B © B O B O B

(Fe-18Cr-8Ni) Weld metal © © © # © O ©

S 3 1 6 L Base metal B © B O B O B O B

(Fe-17Cr-12Ni-2Mo) Weld metal © © © s O • O • ©

A 5 0 8 3 Base metal B © B © B o B © B

( A 1 - 5 M g ) Weld metal © © © # O # O # O

Amount of reduction in (In comparison with base metal

properties at RT)

© Below 20%0 From 20 to 50%# Above 50%

6.2 Low temperature embrittlement of base metal and weld metal.

6.2.1 Tensile PropertiesThe tensile properties of base metals of the stainless steels without hydrogen

charging at RT and 4K were equivalent to the conventional data. At 4K, tensile strength of base metal and weld metal of both steels increased remarkably and reached about three times larger than those at RT. Their elongation and reduction of area at 4K were tend to decrease slightly. Judging from the fact that the most embrittled value of elongation of welds at 4K was still more than 20% and the morphology of the fracture surfaces were completely elastic, it is considered that the tensile properties of SUS304L and SUS316L without hydrogen charging were sufficient for practical use.

In A5083 alloy, tensile properties of base metal and its weld metal without hydrogen charging were nearly the same as conventional data except that elonga­tion of weld at 4K was only 40% of that of base metal.

6.2.2 Charpy impact property(D SUS304L Embrittlement of weld metal and HAZ in absorbed energy was

not observed both at RT and at 4K. Low temperature embrittlement occurred for all kinds of specimens. In particular, the absorbed energy of weld metal at 4K was

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the lowest. © SUS316L The absorbed energy of base metal and weld metal was reducedremarkably by decreasing test temperature to 4K. Particularly, absorbed energy of the weld metal reduced about 85% of that at RT. It is presumed that hydrogen and low temperature embrittlement of weld metal is related to the formation of d -ferrite in the weld metal, since the observation of fracture surface and micro­structure near the fracture surface showed that the crack along the interface of d -ferrite was predominant.

(3) A5083 The impact energy of base metal was about 36J at RT, but it showed about 50% lower value at 4K. The weld metal had a very low absorbed energy, 5.5J, at 4K. Since the absorbed energy(19.2J) at RT obtained in the present study were relatively lower than the conventional values, it is assumed that there were some problems in welding condition in this experiment.

6.2.3 Fracture toughnessFracture toughness of the base metal and weld metal of SUS316L and A5083

was investigated. K]C, converted from JIC obtained from the fracture toughness test with unloading-compliance technique, was used to evaluate fracture tough­ness at RT and 4K.

The base metal of SUS316L exhibited high KIC values both at RT and at 4K. While its weld metal had a high KJC value at RT, it showed a very low K]C at 4K.The decrease in K[C of the weld at 4K was attributed to the presence of brittle S -ferrite phase because in the weld metal specimen tested at 4K, crack was found to extend preferentially along d -ferrite phase.

The base metal of A5083 showed little change in K1C as the testing temperature was decreased to 4K. On the other hand, KJC of the weld metal, which was about 75% of that of the base metal at RT, decreased at 4K by about 50% of that at RT.

6.3 Hydrogen embrittlement of base metal and weld metal

Table 6.2 shows the summary of evaluation on susceptibility to hydrogen by comparing testing values of specimens after the hydrogen charging with those before the charging.

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Table 6-2 Summary of hydrogen embrittlement

Properties of hydrogen charged mat era Is Fatigue life

( H 2 gas )x. Propert ies Tensilestrength

Elongation •Reduction

of area

Charpyabsorbed

energy

Fracture toughness ( J I c )

Fat igue life

(Air)

Materials RT 4K RT 4 K RT 4 K RT 4 K RT RT

S 3 0 4 L (Fe-18Cr-8Ni)

Base ■ eta 1 O © O O © O O O

Weld metal © © O O © • O O

S 3 1 6 L (Fe-17Cr-12Ni-2Ko)

Base metal O O © © © 0 O O © ©

Weld metal © © O 0 e # • • © ©

A 5 0 8 3 (Al-5Mg)

Base metal O © © o © - © o © ©

Weld metal 0 0 © o © - © - © ©

Amount of reduction in properties

after hydrogen charging

(Hydrogen embrittlement)

© Below 20%

O From 20 to 50%

• Above 50%

Susceptibility is unknown

owing to small amount of

the original value

6.3.1 Tensile PropertiesIn the stainless steels, the test results of hydrogen charged specimen showed

the reduction of elasticity at RT and the large reduction of elasticity at 4K. The quasi-cleavage fracture surfaces were observed partly on the fracture surfaces of weld metal specimens. The reduction of elasticity is thought to be due to the change of the stability of austenitic phase in the stainless steels and the amount of d -ferrite in the weld metal. Therefore, it is considered that the relationship be­tween mechanical properties and welding rod, welding method, S -ferrite content should be investigated more in detail hereafter.

In A5083, charging hydrogen into the base metal did not change their tensile properties. On the other hand, the tensile strength and elongation of the welded joint and weld metal decreased at 4K by hydrogen charging. Careful consider­ation must be taken in practical application because after the charging, the amount of drop in tensile strength was very large and the elongation value(7%) of the welds at 4K was very small.

6.3.2 Charpy impact property®SUS304L At RT, the remarkable reducing of absorbed energy did not oc­

curred in both base metal and weld metal by the hydrogen charging. At 4K, how­ever, the absorbed energy of hydrogen charged weld metal was the smallest

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value,56J, which was about 34% of that of uncharged one. It was assumed that the above embrittlement was related to the amount of d ferrite and content of hydrogen in the weld metal.

® SUS316L Hydrogen charging had little effect on the absorbed energy of the base metal at RT. Even at 4K, it reduces the absorbed energy only about 15% of that of the uncharged one. On the other hand, the absorbed energy of weld metal specimen was reduced by the hydrogen charging about 50% of that of uncharged weld metal.

(3) A5083 The absorbed energy of base metal and weld metal at RT did not decreased by the hydrogen charging. At 4K, the effect of the hydrogen charging on the absorbed energy remained not clear.

6.3.3 Fracture toughnessAfter the hydrogen charge, K]c values did not change significantly for the base

metal of SUS316L both at RT and at 4K. However, the hydrogen charging reduced KIC of the weld metal at RT as well as at 4K. d -ferrite / austenite boundary in the weld metal was found to become the preferential path of the crack by the hydro­gen charging and this led to reduction of KIC of hydrogen charged weld metal specimen in SUS316L.

In A5083, K]C test result of the hydrogen charged specimens indicates that effect of hydrogen charging on K]C was not clear both at RT and at 4K. K]C value of A5083 alloy had a excellent correlation with reduction of area in tensile test.

6.3.4 Fatigue propertyFatigue studies on hydrogen charged and uncharged specimens SUS304L,

SUS316L and A5083 alloys were conducted at RT.In SUS304L, hydrogen charging resulted in decrease of fatigue life of base

metal. Although in SUS316L and the weld metal of SUS304L, differences in the morphology of fracture surface between charged and uncharged specimens were observed, there were no evident difference in fatigue life between them. The fa­tigue life of weld metal in A5083 was lower than that of base metal,but no clear change in fatigue life by the hydrogen charging was recognized.

6.4 Tensile and fatigue properties in high pressure hydrogen gas.Tensile and fatigue properties of SUS304L ,SUS316L and A5083 alloy were

investigated at RT both in high pressure hydrogen gas and in argon gas(for com­parison).

CD Tensile properties In SUS304L, hydrogen reduced the ultimate tensile strength, the elongation and the reduction of area and in SUS316L, it reduced the

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elongation and the reduction of area.In both steels, hydrogen also showed marked effect on the fracture surface.

Dimple rupture was observed on y matrix and d -ferrite phase in argon gas, while quasi cleavage fracture was observed on y matrix and cleavage fracture was also observed on d “ferrite phase in hydrogen gas. The hydrogen suscepti­bility of the base metal was larger than that of the weld metal.

In A5083, hydrogen showed little effect on the tensile properties both of the base metal and the weld metal. Only dimple rupture was observed on the fracture surface both in argon and hydrogen gas.

® Fatigue properties In SUS304L, hydrogen reduced the number of cycles to failure in base metal and weld metal. Hydrogen also showed marked effect on the fracture surface in the fatigue test. Striations were observed on y matrix and S “ferrite phase in argon gas, whil equasi cleavage fracture was observed on y matrix and cleavage fracture was observed on d “ferrite phase in hydrogen gas. The hydrogen susceptibility of the base metal was larger than that of the weld metal. In SUS316L, hydrogen showed little effect on the number of cycles to fail­ure, but showed a little effect on the fracture surface. Though striations were observed on y matrix , cleavage fracture was also observed on d “ferrite phase in hydrogen gas. In A5083, hydrogen showed little effect on fatigue life both of the base metal and of the weld metal. Little difference were also observed on the fracture surface both in argon and in hydrogen gas. From the above results, the order of the hydrogen susceptibility to fatigue life of the alloy used can be shown as follows; A5083<SUS316L<SUS304L

6.5 On-site survey & literature surveyVisits to factories related to liquid hydrogen and laboratories with extra-low

temperature testing equipments both in Japan and abroad were made and a lot of useful information was obtained about the application of low temperature materi­als to the liquid hydrogen facilities or about technical problems in evaluating testing at extra-low temperature.In addition, literature survey of extra-low temperature materials and evaluating

test methods at extra-low temperature was also conducted as the last financial year and clear understanding for the low temperature materials and low tempera­ture testing equipments were obtained.

6.6 ConclusionsFrom above research activities, it is concluded that basic and systematic test­

ing for the existing candidate materials was successfully conducted for evaluating their hydrogen susceptibility and low temperature susceptibility. And deep un­

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derstanding of research and development policy of cryogenic materials used for liquid hydrogen storage & transportation system had been acquired.

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7. Sub task 7 : Feasibility study on utilization of hydrogen energy

On the basis of the application scheme of hydrogen we studied in fiscal 1993, we have selected and investigated the following four application techniques this fiscal year.

(1) Cryogenic power generation(2) Power generation(3) Automobile(4) Fuel cell using oxygen and hydrogenAlthough the latest progress in each application technique differs in terms of

utilization of hydrogen, we concentrated our effort in investigating the present trend of development, advantages of utilizing hydrogen, and problems in technical development for each application technique.

In the area of cryogenic power generation we studied mainly about the power generation cycle using liquefied hydrogen on the basis of the LNG cryogenic power generation, while in the area of power generation we proposed a new sys­tem using hydrogen as its fuel and picked up technical problems. In the area of automobile, we first investigated the circumstances of the future automobile and then, based on the result of the investigation, we analyzed fundamental direction and position in developing hydrogen car. In the area of fuel cell, we selected five different types of fuel cells and studied utilization of hydrogen and oxygen in terms of technique and application.

Investigation and study about each application technique includes the follow­ing.

7.1 Investigation and study about cryogenic power generationCryogenic power generation is one of effective applications of cold heat of lique­

fied hydrogen. We studied what power generation cycle would be suitable for liquefied hydrogen cryogenic power generation on the basis of LNG cryogenic power generation which has already been put into practice.

The LNG cryogenic power generation cycle is classified broadly into Rankine cycle and Brayton cycle, out of which only the Rankine cycle has been put in service in a practical or demonstration plant. The Brayton cycle, in which the compressor inlet temperature of the gas turbine cycle using LNG combustion gas is lowered by the cold heat of LNG to reduce the compressor power, is still under study because of technical problems and high installation cost.

The Rankine cycle comes in an LNG direct expansion system and a secondary

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medium system, and a combination of the two. For the liquefied hydrogen cryo­genic power generation system, a combination of the hydrogen direct expansion cycle and the secondary medium Rankine cycle is suitable in view of effective utilization of cold heat exergy and high feasibility of practical plant. Because the boiling point of liquefied hydrogen (20.28K) is far lower than that of LNG and accordingly the temperature range up to the normal temperature is broad, it is necessary to install multiple secondary medium Rankine cycles and select suitable working gas (secondary medium) for the temperature range to make effective uti­lization of the cold heat.

For example, when hydrogen is circulated in a cycle where it is pressurized up to 5.17 MPa (51 atm) and then expanded to 0.963 MPa (9.5 atm) by a reheating two-stage turbine (hydrogen direct expansion cycle), the utilization factor of the cold heat exergy is 13.9%. To the contrary, when each argon Rankine cycle and propane Rankine cycle (two cycles) are installed as the second medium, the utiliza­tion factor of the cold heat exergy improves to as high as 24.4%.

Because the feeding condition of hydrogen, which is determined by the applica­tion mode of hydrogen, has not yet been defined, we do not attempt to cover the optimum operating condition of the cycle nor the most suitable type of operating gas in this study. When the application mode of hydrogen is clearly defined, however, it is necessary to examine these matters.

Although our study was mostly concentrated on the cycle itself, it is necessary to develop equipment and devices applicable to a cryogenic system, including liquefied hydrogen pump, turbine, and heat exchanger, which are required to real­ize the above cycle. It is anticipated that those equipment and devices can gener­ally be developed on the basis of those currently in service for the LNG cryogenic power generation. However, because the material property of liquefied hydrogen is significantly different from that of LNG, for example, it is far colder in tempera­ture and lower in density.

In addition to the above, total design of the cryogenic power generation system must be determined in consideration of many other factors including the stability of the system against load variation and the economy. It is also necessary to provide a sub system which, in case that the cryogenic power generation system is shut down due to a failure, can supply hydrogen gas at prescribed pressure, temperature, and volume to the processes requiring hydrogen.

7.2 Investigation and study about power generationStationary power generation system currently in service includes general

large-scale electric power generation system and so-called electro thermal cogen­eration system in relatively small scale. We have investigated and studied the

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hydrogen cogeneration system.Diesel engine for cogeneration employs light oil or kerosene as its fuel. To

substitute hydrogen for the fuel, the point is how to minimize emission of air pollutant and increase thermal efficiency. Since use of hydrogen as the fuel does not cause any emission of particles, or black smoke and hydrocarbon, it is only necessary to give consideration to NOx as possible air pollutant. The simplest solution is to avoid using the air as oxidizer but to use inert gas, such as argon or helium, or steam as the working gas. Because such inert gas is composed of monoatomic molecules, its ratio of specific heat is higher than that of the air, and accordingly improved thermal efficiency can be expected from a thermodynamic point of view. On the other hand, although the above effect cannot be expected from use of steam, adding a Rankine cycle to the system as the bottoming cycle will make it possible to recover the waste heat energy and hopefully improve the thermal efficiency.

In this investigation and study, we have proposed six different types of engine systems using hydrogen as the fuel.

Because the proposed power generation system not only features zero NOx emission and high thermal efficiency but is free from black smoke emission, there is no need to limit the output to reduce concentration of the black smoke emission and therefore there is a great possibility of increasing the output. Accordingly, the proposed system can be called ’’Zero Emission CryoDiesel” power generation system.

The following three brief categories can be derived from the proposed system. ® Closed circulation type H2/02 combustion diesel system

This system aims at higher efficiency resulting from diesel combustion and NOx free operation resulting from hydrogen and oxygen combustion. By employ­ing a closed circulation design with monoatomic gas or steam as the working gas, this system aims to increase thermal efficiency of the diesel cycle in case of using monoatomic gas or to increase thermal efficiency of the condensing turbine or the cogeneration system itself.® Open cycle air combustion engine system

Basic concept of this system, which intakes the atmospheric air to run the hy­drogen combustion cycle, is the same as that of the conventional engines. The system aims to achieve lower NOx emission and higher thermal efficiency by means of lean burn. To eliminate knocking due to premix combustion, a system using a rotary engine and a system employing a sub-chamber jet method have been proposed. It is highly probable that both of them are realized in the near future as the conventional technique improves.(D New Sterling engine

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This is a new internal combustion Sterling engine, employing hydrogen-oxygen catalytic combustion. Zero NOx emission and high thermal efficiency can be ex­pected.

We have picked up common technical problems which must be resolved to put the above three different types of hydrogen combustion power generation system into practice.

The closed diesel system in (T) above leaves the most problems yet to be solved. In particular, the technique of jet and diffusion combustion of hydrogen has not yet reached a practicable level although it is already introduced in several cases as trial. In addition, we can say that the combustion technique of hydrogen in the monoatomic gas or steam still falls under the category which has not yet been established technically. There still remain a number of combustion technique for hydrogen yet to be solved, some of which are high pressure jet technique, acceler­ated diffusion and mixing technique, and firing technique.

Development of the open air combustion system in ® above is regarded very much practical because most of the knowledge obtained through the past develop­ment of different types of hydrogen engines can be applied basically. We evaluate that the system can possibly be put into practice through short-term development.

The catalytic combustion system in ® above is a technique that has almost been established firmly. We however still think it necessary to investigate feasi­bility of internal combustion Sterling engine, expected increase in thermal effi­ciency, and characteristic of the system.

We believe the proposed development of the power generation systems using hydrogen, which we have just reviewed in this investigation and study, complies with the concept of the next generation system using hydrogen. It is highly recom­mended to continue investigation and study.

7.3 Investigation and study about automobileTo set more practical objectives of the development, including standing position

and purpose of hydrogen automobiles, we have investigated roles of today’s auto­mobiles, various social requirements for the automobiles and technical develop­ment to meet the requirements, and direction of future technical development. In parallel with the above, we have analyzed current and future development level of the technology for hydrogen automobiles and summarized technical matters yet to be developed.

The result of our investigation was as follows.

® Japanese automobile transportation predominates the material transportationat present and has been significantly contributed to our convenient social liv-

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ing as a means to move and transport people and materials for commuting, leisure, and shopping. On the other hand, spread of a countless number of automobiles as a result of pursuing the convenience has not only given a rise to local and global environmental issues and energy issues but lowered the trans­portation efficiency because of traffic backup resulting from delayed develop­ment of driveways. To cope with these problems, conventional fuel automo­biles have been subjected to various technical development for cleaning the exhaust gas and improving the fuel consumption to conform to the regulatory limit Emphasis has been put on developing and putting alternate fuel automo­biles, using methanol or natural gas, and electric automobiles into practice.

(D In the over all trend of the automobiles, the present hydrogen automobile, in terms of technical development on fuel conversion of automobiles, is regarded as a less air-polluting, energy-saving alternate energy automobile to be com­pleted after the year 2010. On the other hand, in terms of technical develop­ment on electrical automobiles, development of hydrogen automobile is re­garded as the development of hydrogen battery automobile or, in a more distant future, that of fuel cell automobile for increasing the driveing distance. It is expected that the application of the hydrogen automobiles include passenger cars and buses.

(D The above understanding or expectation is derived from the pending technical problem, which is common to other alternate fuel automobiles, that the energy storage density of the automobile fuel is much lower than that of conventional gasoline or kerosene fuel. Accordingly, the key point for developing the hydro­gen automobile is to develop suitable fuel tanks for automobiles.

® However, it is expected that need for developing the hydrogen automobiles will surely increase bacause of various pressing requirements for automobiles, in­cluding energy issues, environmental preservation, and improved or more con­venient social living. To be able to meet the demands, we have proposed funda­mental technical development, comprising development of hydrogen automo­biles for transportation facilities and battery cells for automobiles, and techni­cal development for constructing infrastructures such as hydrogen service sta­tions.For us to propose the technical development of the hydrogen automobiles to be

realized after the year 2000, we should not limit our effort of development to the technique on fuel tanks, which is a simple elementary technique, but challenge to develop innovative hydrogen automobiles. It is also necessary to create a clear vision of the automobile including that of the transportation issues which the automobile transportation is now facing with.

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7.4 Fuel cell using oxygen and hydrogenIf hydrogen can be utilized as the fuel of the fuel cells, existing reformers which

produce hydrogen from petrochemical fuels such as natural gas (methane) are no longer necessary, resulting in reduced facility cost, improved thermal efficiency, enhanced operability, and reduced facility installation area. Because of this, fuel cells are expected worldwide to be a very effective application technique of hy­drogen in the age of hydrogen energy in the future. If oxygen can be produced easily by utilizing the cold heat of the liquefied hydrogen that is transported by the sea, it is possible to further improve the power generation efficiency by using the oxygen as oxidizer for the fuel cells.

In our study, we regard the fuel cells using hydrogen and oxygen (air) as the primary application technique of hydrogen and have investigated the following technically and in terms of application.(D Starting with the investigation of present techniques for various fuel cells, we

make clear loss of various fuel cells through utilization of hydrogen and oxygen (air), and study possible problems in the development.

© We estimate applicable fields of the fuel cells using hydrogen and oxygen (air), investigates possible applications of the fuel cells, and, at the same time, study possible problems in introducing and popularizing the fuel cells in the fields.

© We estimate market size and demand for hydrogen in each applicable field.® According to the results from CD to ® above, we investigate the future of the

fuel cells using oxygen and hydrogen.

The results were as follows.

Among the available fuel cell techniques, the most highly developed is the phos­phoric acid type cell. In the development of the fuel cells using oxygen and hydro­gen, it is found that the fuel cell of low temperature operating type, particularly solid polymer electrolyte type, enjoys the greatest advantage of using hydrogen and that, if oxygen is used as oxidizer, 60% or higher power generation efficiency can be expected with the solid polymer electrolyte type and about 50% or so can be expected with the phosphoric acid type or alkali type. However, because there is no limitation to the quantity of CO with the molten carbonate fuel cell of high- temperature operating type and the solid oxide fuel cell from the beginning and also because it is possible to reform the inside of the fuel cells using petrochemical fuels, it is concluded that we cannot expect much advantage in using hydrogen.

As a result, in the application field of the fuel cells using oxygen and hydrogen, it is expected with high probability that the fuel cell of low-temperature operating type can be applied to the power adjusting power supply for the electric utility,

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residential use (independent house or apartment houses) on the basis of cogenera­tion, and many other applications including transportation and mobile power sup­ply where any or some of exhaust gas, noise, vibration, low efficiency, and con­tinuous operating hours cause problems.

Subjects of the technical development for each type of fuel cell include; im­proved life during the hydrogen oxygen operation, higher current density, protec­tion from COg in the air for the alkali type; water repellent performance of the electrodes for the solid polymer electrolyte type; optimized system for C02 recy­cling for the molten carbonate type; cell material with wider allowable operating temperature range for the solid oxide type. Problems common to all types of the fuel cells are to establish a cell cooling and heat recovery system, establish an optimized operation control method, and to ensure operation reliability and safety (all these become more important for the high-temperature operating type), and to establish a hydrogen recycle and created water removal system.

Common problems to be solved in introducing and popularlizing the fuel cells in the applicable fields include establishment and optimization of a hydrogen supply system, compact design of the cell body, safety measures for the entire system, and political support for the introduction of the fuel cell. In the field of cogenera­tion, we think it important to provide an optimum system suitable for electro­thermal demands of each user. In the field of transportation and mobile power supply, we think it important to reduce weight of the hydrogen storage container and take necessary measure for outdoor utilization.

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8. Subtask 8 : Development of a hydrogen-combustion turbine

8.1 Study for an optimum system for hydrogen combustion turbine

8.1.1 Outline of the R&D results in the past yearIn FY1994, the survey on high temperature properties of the gases used in the

H2 combustion turbine systems, and examination on the power generating cycles, that enables us to obtain higher efficiency, were performed.(D Concerning to the high temperature properties of the steam, ”NBS Steam

Tables” is the favorable, because it covers the most wide range and the data in it is well fits to the JSME steam tables.

(2) According to the simple calculation of the efficiency of each proposed cycles, the efficiency of each cycle becomes higher in following order. (Where maxi­mum temperature is set at 1700°C)Inert gas circulation cycle < Steam circulation cycle < Steam direct expansion

cycle < Topping extraction cycle and Bottoming reheat cycle

8.1.2 ObjectivesIn FY1994, examination on optimum cycle are done with doing following items.

- The calculation of cycle efficiencies in same condition.• According to the rough design of main component, improvement of the assumed

efficiencies of turbines and compressors, and consideration of the feasibility of each component.

• The starting up procedures.

8.1.3 Outline of the R&D results in FY1994

(1) Comparison of each cycles by calculation in same condition.The basic condition for cycle calculation were established(Table 8-1-1), and

efficiencies of each cycles are calculated under this condition. (Table 8-1-2)

(2) Sensitivity studiesSensitivity studies were performed to evaluate the influence of operating and

design parameters. As a result, Inert gas circulation cycle can not achieve the efficiency over than 60%.

(3) Rough design of main components

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A rough design of main component were done to improve the assumed efficiency of each component and examine the feasibility of the component.(Table 81-3)

8.1.4 Future plansIn FY1995, conceptual design of 500MW power plants using selected cycles

will be performed, and basic plans of pilot plant will be examined.

Table 8-1-1 Assumption for Estimating Cycle Performance

Parameter Value

Maximum Temperature of the cycle 1300, 1500, 1700, 20001:

Compressor adiabatic efficiency 0.89

Expander adiabatic efficiency 0.93

Turbine Coolant Rate 0%, 15%

Combustor Combustion efficiency 1.0

Combustor Pressure Drop 5% of inlet

Heat Exchanger Pressure Drop 5% of inlet

Pumping Power not considered

Component Mechanical efficiency 99%

Generator electrical efficiency 98.5 %

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Table 8-1-2 Estimated gross efficiencies of proposed cycles calculated with the basic condition

Cycles Inert Gas Circulation Cycle -Ar Inert Gas Circulating Cycle-COz Bottoming Reheat Cycle *' Bottoming *2

Maximum Temp.('C) 1500 1700 1500 1700 1500 1700 1500 1700

Coolant Rate (%) 0 15 0 15 0 15 0 15 0 15 0 15 0 15 0 15

Efficiency (HHV,%) 51.1 48.8 54.0 52.0 52.2 50.3 55.4 53.9 60.4 58.7 61.5 60.2 61 60.1 62.2 61.4

Cycles Topping Extraction Cycle Steam Direct Expansion Cycle New Rankine Cycle Reheat Rankine Cycle*3

Maximum Temp.("C) 1500 1700 1500 1700 1500 1700 1700

Coolant Rate (%) 0 15 0 15 0 15 0 15 0 15 0 15 0 Film Closed

Efficiency (HHV,%) 60.1 59.1 61.5 60.5 56.4 54.8 58.5 55.5 58.7 57.2 60.2 58.9 65.3 60~61 63''-64

1 Re-combustor is placed after bottoming first turbine.2 Re combustor is placed before bottoming first turbine.3 The maximum pressure is set at BOObar. When the maximum pressure is set

at lOObar, the efficiency decrease by 3points.Concerning to the effect of the coolant rate, both the conventional film cool­ing and the steam closed cycle cooling are considered here.

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Table 8-1-3 Dimensions of turbines (500MW New Rankine Cycle Power Plant)

Unit H T I H T I L T L T

Inside diameter at the turbine inlet m 0.81 0.42 2.59 1.68

Outside diameter at the turbine inlet m 0.84 0.51 2.80 2.50

Inside diameter at the turbine outlet m 0.89 0.36 2.51 1.68

Outside diameter at the turbine outlet m 0.94 0.59 3.08 3.37

length of the passage m 1.60 0.54 3.20 3.60

Number of the stages Wt 12 3 6 4

Turbine speed rpm 3,000 17,700 3,000 3,000

Overall adiabatic efficiency % 77.2 92.5 94.6 93.0

104

105

(e)Steam direct expansion cycle

(a)Inert gas circulation cycle (b)Topping extraction cycle

(f)New rankine cycle

(g)reheat rankine cycle(c)Bottoming reheat cycle(*1) (d)Bottoming reheat cycle(*2)

Fig. 8-1-1 Hydrogen combustion turbine cycles

8.2 Development of combustion control technology

8.2.1 R&D goalsThe research objective is to establish the technologies needed to build a hydro­

gen combustion turbine pilot plant, by conducting necessary studies and develop­ing component technologies. In order to accomplish this objective, a reaction analysis of hydrogen/oxygen combustion and investigation of the basic structure of a hydrogen/oxygen combustor was performed in 1993. Results showed that the hydrogen/oxygen combustor needed a burner with superior combustion sta­bility and stoichiometric combustion.

8.2.2 ObjectiveIn order to define the basic structure of a burner to be used in a hydrogen/

oxygen combustor, the fundamental combustion characteristics of hydrogen/oxy­gen mixed with steam were investigated using burner combustion test devices.

The combustor wall cooling method with steam, as well as the combustion gas dilution method, were also investigated.

8.2.3 Burner combustion test(1) Combustion test under atmospheric pressure conditions using three burner

types (coaxial, collision, 02 swirl) were performed to determine the effect of the burner types on combustion stability. As the result of the test, it was found that combustion stability was the greatest with the 02 swirl burner type, followed by the coaxial burner and the collision burner, when 02 concentration was more than 60%. Stability was nearly same for all three burner types when 02 concentration was less than 60%.(Fig.8.2.1 ^Fig.8.2.2)

(2) Combustion test of a pilot burner(coaxial type) to be used in a hydrogen/oxgen combustor was performed to determine the conditions of combustion stability. As a result of the test, it was confirmed that the pilot flame was stable at an equivalance ratio range from 0.9 to 2.0. The flame was also observed with and without 02 swirl.(Fig.8-2 3 ^-Fig.8-2-4)

(3) A study was performed to confirm the blow-out limit of flames and the hydro­gen and oxygen concentration in the combustion gas using a multi-hole jet burner type (hydrogen:multi-hole jet, oxdizing agent: oxgen-f- steam (02:21%)). As the result of the test, it was found that the equivalence ratio of blow-out limit

was 0.1 when 02 concentration was 21% and that the equivalence ratio of blow­out limit was constant for steam temperatures from 200X3 to 350X3 . Concerning

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hydrogen and oxygen concentration in the combustion gas, when hydrogen and oxygen concentration in the combustion gas was lowest, the equivalence ratio was nearly 1.08. .(Fig.8-2-5 ^Fig.8.2.8)

8.2.4 Combustor wall cooling method and combustion gas dilution method.It was found that the combustor wall can be cooled to a predetermined tempera­

ture by using convection cooling outside of the liner together with film cooling inside of the liner and a thermal barrier coating on the liner itself. Convection cooling and a thermal barrier coating are also used on the transition piece. A study was performed to confirm the flow pattern in the combustor using CFD.

It was observed that steam from all holes moved to the core of the combustor, and a circulation flow was formed at the liner dome of the primary combustion zone. The effectiveness in achieving flame stability was thus demonstrated.

8.2.5 Future OutlookContinuing on the path started by the 1994 R&D activities, the most suitable

structure for a burner to be used in a hydrogen/oxygen combustor will be stud­ied, and cooling and diluting structure will be investigated in detail. A study will be performed on the conceptual design of a combustor for use in a 500MW hydro­gen combusution turbine.

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^ To Exhaust Duct

Combustor

WV1(Inlet Valve)

WV3(Outlet Valve)

Cooling Water

PCV7Pilot Burner02-Steam Mixture

Hg-Steam MixtureBurner PCV6

FV.WV : Valve: Filter: Thermo Couple : Pressure Control Valve

Shop Air

Impinge Type Coaxial Type Coaxial Swirl Type Schematic Structure of Injectors

Figure 8-2-1 Experimental Apparatus

—@—Impinge Type - -a - - Coaxial Type

-•B--Coaxial Swirl Type

Stjable Flame

X 40

! Blovy-out

02 vol%

Figure 8-2-2 Stable Flame Region

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(^Combustor (Impingement + film cooling)*)

(Hydrogen)

V "nozzlT J (steam + Oxygen) (steam)

Outlet gas temperatureHeater

208kg/h2.5MPa

SatulationGas sampling

probe

Gas chromatography

60.29 kg/h

7.53 kg/h

Fig. 8-2-5 Diagram of burner foundamental test

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Steam temperature Ts : 200 °C Pressure P: 0.17 MPaMean velocity Vr': 17 m/s

Oxygen concentration 02 (%'

Fig. 8-2-6 Flame Stabilization: effect of oxygen concentration

Oxygen concentration 02 : 21 % Pressure Mean velocity Vrz: 17 m/s

crSteam temperature Ts (°C)

Fig. 8-2-7 Flame Stabilization: effect of steam temperature

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Steam mass flow rate Oxygen mass flow rate Steam temperature Pressure Mean velocity

Gg: 160 kg/h G02:35.5 kg/h

TS :445°C P: 0.53 MPa

Vr': 17 m/s

Equivalence ratio <j>

Fig. 8-2-8 Combustion characteristic: exhaust gas compositions

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8.3 Development of turbine blades, rotors and other major components

8.3.1 Research ObjectivesAs a part of hydrogen utilizing new technology development WE-NET Project),

the survey and research as well as the basic technology development, which are necessary for the development of pilot plant, are implemented, and the technologi­cal means required for the research of key technologies in the next phase are studied.

Research contents in this fiscal year;The surveys and component tests on the cooling technology of turbine moving

and stationary blades are conducted to develop the conceptual design of blade cooling systems and the rotor cooling test methods and equipment are investi­gated.

8.3.2 Outline of Research Achievement(1) Development of Cooling Technology for Turbine Moving and Stationary

BladesIn this fiscal year, the conceptual design of the following 3 different schemes

have been developed to establish the feasibility of moving and stationary blade cooling in 1700°C class high temperature condition.

* Enhanced film cooling scheme’ Enhanced internal cooling scheme* Full coverage film cooling(FCFC) schemeIn addition to the above, the heat transfer and cooling tests on elements level

have been implemented to have the result reflected to the conceptual design.First, in Enhanced film cooling scheme, the selection tests of the cooling hole

geometry with a high cooling effectiveness have been completed and the cooling hole having long horizontal length have been selected (with more than 15%abs superior cooling effectiveness over the conventional diffuser hole).

Next, by means of the enhanced film cooling scheme based on the above results, the feasibility design of the 1700°C class first stage moving and stationary blade have been studied and the results of cooling medium reduction by 1.7% to 1.2% (absolute value, in terms of percent of the inlet flow rate) over the conventional technology are obtained.

In the enhanced internal cooling scheme, the characteristics identification tests of the high heat transfer performance turbulence promoters at low aspect ratio has been completed. The trial design of the first stage moving and stationary blade of 1700°C class operating temperature has been studied based on this re-

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suits with= the conclusions that the target blade cooling performances can be fea­sible. In addition, the study of high pressure and low temperature cooling medium supply system (300°C) for the moving and stationary blade has been implemented.

A trial design of the first stage moving and stationary blade of 1700*0 class temperature has been studied according to the full coverage film cooling (FCFC) scheme, and the prospect has been established to realize the cooling performance near the target. In order to identify the performance of the components employed in the trial design, the plan of the heat transfer performance test to be imple­mented in future has been formulated.

In addition to the above activities, the survey of papers published last 10 years (from 1985 to 1994) on the film cooling technology has been conducted. The basic film cooling tests based on this data accumulations will be scheduled for the next term.

In addition, the conceptual design on the film cooling scheme with different features from above has been under studied.

(2) Development of Rotor Cooling TechnologyIn this fiscal year, the studies on the test method, equipment and instrumenta­

tion guideline for identification of the rotor heat transfer performance have been mainly implemented.One sub contractor has completed the studies on the test method and equipment in the rotating field, and the study on the thermal boundary conditions of rotor disc, in order to clarify the rotor heat transfer performance.

Another sub contractor has completed the instrumentation plan and the mea­surement method of rotor heat transfer performance (the distribution of the hot gas streams diffused into the cavity and disk surface), to conclude the design and manufacture of the test model.

8.3.3 Future CommitmentConcerning the development of the cooling technology for the turbine moving

and stationary blades, it is being planned to implement the identi- fication of the total blade cooling performance at component level, the optimization of the blade cooling design conditions to match the cycle characteristics, the mechanical evalu­ation of the blade design by means of thermal stress analysis, the identification test of the aeronautic and heat transfer performance of blades at component level based on the achievement of this fiscal year.

Concerning the development of the rotor cooling technology, it is being planned to clarify the heat transfer performance by implementing tests on the test equip­ment prepared in this fiscal year.

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8.4 Development of major auxiliary equipment

8.4.1 Research ObjectivesAs a part of the hydrogen utilizing new technology development(WE-NET), the

survey and research as well as the basic technology development which are neces­sary for the development of pilot plant are implemented, and the technological means required for the research of key technologies in the next stage are studied.

Research contents in this fiscal year;The surveys and researches on the heat transfer promotion technologies and

type, construction, material of high temperature heat exchanger are implemented. The studies on the basic technology of high efficiency and compact cryogenic heat exchanger for production of liquid oxygen are implemented, and in addition, the feasibility of improving the performance(energy consumption per unit oxygen production) of oxygen production system utilizing cold heat of liquid hydrogen are studied.

8.4.2 Outline of Research Achievements

(1) The following researches have been implemented in this fiscal year on thedevelopment of cold heat utilization technology.

* Survey and study of fundamental conditions of vaporizing system.* Survey and study of site conditions of cold heat utilization plant.* Study of energy per unit oxygen production.* Study of system performance.Based on the survey and study of the fundamental conditions of hydrogen va­

porizing system, it has been determined that the open rack system using sea water can be adopted as the design of liquid hydrogen vaporizing system. In addition, the thermal characteristics and the transport characteristics of the para hydrogen and ortho hydrogen have been studied and reviewed and it was revealed that aluminum alloy can be applied as the material.

Through the survey and study of site conditions of cryogenic heat utilization system, the amount of cryogenic heat which can be utilized in the oxygen produc­tion process has been estimated. It was also found that nitrogen has the high potential as the cryogenic heat transfer medium. The oxygen production schemes have been compared and evaluated to establish the basic concept of the system.

In the study of energy consumption per unit oxygen production, the studies have been conducted on the system by which the unit energy input can be reduced to less than 0.4 kWh/Nm3. In addition, studies have been implemented on the amount of liquefied gas generated as a byproduct.

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In this fiscal year, simulation studies have been conducted on the system with the emphases placed on the single column system, to analyze the oxygen purity, characteristics of byproducts, and the reduction of system energy consumption. (A prospect has been established to drastically reduce the energy consumption per unit oxygen production down to 0.33 kWh/Nm3 or so)

(2) The following efforts have been implemented in this fiscal year for the devel­opment of high temperature heat exchanger.

* Survey and study of heat transfer promotion technology.* Survey and study of heat exchanger type and construction.* Survey and study of heat exchanger materials.As the result of survey and study of heat transfer promotion technology, it was

found that the segment fin is effective for the convection heat transfer outside the tubes.In addition, it was found out that the active utilization of radiation heat transfer (radiation plate, etc.) is promising as the means of promoting heat transfer outside tubes.

Through the survey and study of heat exchanger type and construction, a bayo­net type is preferable when the structural integrity at high temperature is re­quired, and a straight tube or U tube type should be applied for the regenerative heat exchanger. A long term component developments are required for the ce­ramic type heat exchanger.

As the result of the survey and study of heat exchanger materials, the high temperature strength of nickel, cobalt and niobium based alloy is limited to tem­perature of 1000 *C.

It was found that, although ceramics have superior strength at high tempera­ture condition, there are still problems of material jointing and leakage.

8.4.3 Future CommitmentIt is being planned to survey a wide range system design of the oxygen produc­

tion system based on the result of this fiscal year for the development of cryogenic heat utilization technology.

As the studies of component level of high temperature heat exchanger have been almost completed , it is being planned to evaluate its feasibility as a practical equipment.

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8.5 Development of super-pyrogenic materials

8.5.1 R&D goalsIn the World Energy Network(WE-NET) project, a hydrogen combustion tur­

bine, which is expected to have good preservation of the environment and achieve greatly high efficiency up to 55-60%,will be developed as one of the utilization techniques of hydrogen. For the purpose, technical subjects essential to the devel­opment are surveyed, and then the fundamental technology required for develop­ing the elemental technology of a pilot plant. In a field of ultrahigh temperature materials technology, machining techniques, property evaluation and structural design application of the materials are fundamentally studied to select the ultra- high-temperature materials for their applications to hydrogen combustion turbine components through improvements and advances of existing materials.

In FY’94 which is the second year of Phase I program in this project, focusing on heat-resistant alloys, intermetallic compounds, ceramic and carbon/carbon composite materials which are expected to be applicable to the hydrogen combus­tion turbine, design and experimental production of these materials are conducted and then their basic properties are obtained, based on the technical subjects pointed out in FY’93. Also, some technical problems to be solved in future are found.

The results obtained are summarized as follows:

(1) Development of advanced single-crystal superalloy and materials for hybrid cooled blade

• Experimentally making TMS63Mod. which is a modified alloy of the single- crystal(SC) superalloy developed in Japan, this SC alloy was found to have the almost same strength as the most extreme SC alloy in the second generation.

- Two kinds of hollow and porous textile were experimentally made, and then the textile made by burning an organic fiber interwoven with a ceramic fiber was selected. Experimentally making a fiber-reinforced ceramic(FRC) shell model by using a CVI(Chemical Vapor Infiltration) method for forming a SiC matrix on the textile selected, a basic technique for the formation of FRC was established.

(2) Development of ODS(oxide dispersion strengthened) alloy and thermal barrier coating(TBC) for cooled vane

• A structure model of porosity-controlled TBC was proposed. Also, coating treatment was tried after selecting each material for the structure model, and then technical problems to be improved were found.

• The high-temperature oxidation behavior at 1150°C and an air environment

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was examined for the ODS alloy selected as a candidate material for the cooled vane. The air flow through the porous coating layer was experimentally char­acterized.

(3) Development of intermetallic compounds(IC) material• The elements added to MoSi2 with high melting-point were selected to improve

the mechanical properties and oxidation-resistance of the IC material. Compar­ing applicability to manufacturing process between solution and powder meth­ods, the powder method being able to control the chemical composition of an IC material was found to be better.

• The oxidation resistance properties of the materials made experimentally were obtained at high- and intermediate-temperatures(l70O^C and 500 °C,respectively) in an air environment.

(4) Development of ceramic-matrix composite(CMC) material• Conducting high-temperature heating tests in air and argon environments at

1300, 1500 and 1600°C by using the CMC material(SiC matrix with a long fiber of SiC) made experimentally, its oxidation resistance and thermal degrada­tion properties were obtained. Some technical problems to be solved as well as their countermeasures were found from the test results.

- Experimentally making coating materials of A1203, Zr02 and Y203, their oxida­tion resistance properties were obtained from heating tests at 1300°C in an air environment.

(5) Development of multi-structure ceramic material and evaluation method of fracture behaviors at ultrahigh temperatures under mixed-mode conditions

• A basic concept of multi-structure ceramic material was proposed. Also, ex­perimentally making a CMC material((Si3N4+TiN)matrix/SiC fiber) which is a candidate for a core material of the multi-structure ceramic, it may be possible to increase its toughness and introduce a function of fracture detection into the core material.

• An environment-controlling system was framed in an apparatus for corrosion tests under ultrahigh-temperature H20+H2 environments. Conducting corro­sion tests as well as bending tests after the corrosion tests on Al203/SiC and SiC by means of the apparatus, it was found that the two materials showed similar behaviors of corrosion-resistance and strength-degradation.

(6) Development of 3-dimensional fiber-reinforced composite material• A candidate material for a reinforced fiber, fiber orientation and others were

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examined for carbon-carbon composite and CMC materials with a 3-dimen­sional textile and fiber-reinforced structure. Experimentally making sample materials based on the results, their mechanical properties including bending strength at 2000°C were obtained.

(7) Development of experimental evaluation method for ultrahigh-temperature materials

• As a part of evaluation of mechanical properties, it was found that there was no change in the tensile strength of a carbon-carbon composite material after cyclic loading at 1600°C. Also, strain measurement procedure for creep tests was improved.

• A method of measuring the thermal properties of a carbon-carbon composite material was partly improved. A high-temperature X-ray diffraction method was found to be applicable to analyses of material structures and reaction be­haviors at high temperatures.

• Existing apparatuses were modified to conduct oxidation and erosion tests of the effects of gaseous and flow conditions on the oxidation resistance of a mate­rial.

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9. Subtask 9 : Study of innovative, and leading technologiesExecutive Summary

9.1 PurposesThe aim of the surveys and studies dealt with in this section is to facilitate

research and development activities under the WENET project through the in­vestigation and assessment of conventional technologies as well as innovative, pioneer technologies (including the minimum elemental research as necessary). Promising technologies found by these studies will be examined closely and pro­posed as new areas or items of technological development for the project.

In phase I, Subtask 9 calls for carrying out the following activities. ^Establishment of investigation method for and actual investigation of innova­

tive, pioneer technologiesAn intermediate scenario that takes into account the process of introducing a

hydrogen energy system gradually will be worked out in a bid to set specific targets step by step and to look for those technologies which are capable of attain­ing such targets.

b. Establishment of evaluation method for and actual evaluation of innovative, pio­neer technologiesA wide variety of technologies with significantly different lead times will be

assessed by a common criterion through the establishment of an evaluation method that does not depend on the technology to be assessed.

c. Elemental research on innovative, pioneer technologiesA basic study on the minimum required scale will be conducted on those tech­

nologies which are found to have sufficient technological significance and to re­quire elemental research for assessment as a result of the investigation in para­graphs a and b above.

d. Survey on trends of conventional technologies and their evaluation Conventional technologies will be examined to find whether some of them may

become promising WE NET components, depending on the trends of their im­provements. Then the usefulness of some technologies will be evaluated.

e. Study on new areas and items of technology developmentPromising new technologies found by surveys and studies in paragraphs a

through d above will be examined closely and proposed as new areas or items of technological development under the WE-NET project.

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9.2 Details of research activities in fiscal 1994Research activities in fiscal 1994 were focused on establishing an investigation

method and evaluation criteria for innovative, pioneer technologies.a. Establishment of investigation method for and actual investigation of innova­

tive, pioneer technologiesi .Establishment of investigation method

The WE NET project has to deal with a great diversity of technologies which require a long period of research activities. This makes it very difficult to narrow down the range of technologies that have to be investigated and evaluated. A technology investigation method was developed to solve this problem. The follow­ing are its major features:

• Preparation of an intermediate scenario that takes into account the process of gradually introducing a hydrogen energy system.

• Identification of those technologies which are necessary to make the scenario viable and, as such, have to be covered by research and development activities.

• Feasibility study on the viability of the scenario.• Identification of the technologies that cause a bottleneck in making the scenario

viable.• Investigation of the technologies that can break the bottleneck.

ii .Technological surveys for intermediate scenario and feasibility studyA standard application form for technological researches was worked out and

the following investigations were started.• Investigation of technologies for developing new intermediate scenarios or re­

fining the existing ones.• Investigation of technologies for carrying out feasibility studies.

b. Establishment of evaluation method and actual evaluation of innovative, pioneer technologies

i .Establishment of evaluation criteriaA new evaluation method was developed which can assess the viability of inno­

vative, pioneer technologies as a future principal component of the WE NET with respect to various (nine) items, such as environmental load, economical efficiency, technological maturity and required lead time, using a common criterion that does not depend on the technology to be assessed.

9.3 Research plan for fiscal 1995a.Investigation of innovative, pioneer technologies

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In order to examine the appropriateness of the method established in fiscal 1944 and to investigate related technologies, the following research activities will be carried out in fiscal 1995:

• Investigation of technologies for developing new intermediate scenarios or re­fining the existing ones.

• Investigation of technologies for carrying out feasibility studies.• Performance of a feasibility study and the identification of those technologies

which cause a bottleneck in making the intermediate scenario viable.

b. Evaluation of innovative, pioneer technologiesThe appropriateness of the method established in fiscal 1994 will be examined

and assessed with respect to:• Whether it is appropriate as a technology to make the intermediate scenario

viable;• Whether it is worth a feasibility study; and• Whether it is capable of breaking the bottleneck.

c. Survey on Trends of Conventional Technologies and Their Evaluation Conventional technologies will be examined and evaluated by the same method as for innovative, pioneer technologies to find whether they can be promising WE NET component technologies, depending on the trends of their improvements.

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If you wish to cite the contents of this report, please contact to obtain prior consent as follows;New Energy and Industrial Technology Development Organization

(NEDO)Hydrogen, Alcohol and Biomass Department

Tel: +81-3-3987-9481 Fax: +81-3-5992-1349

For the summary of research results on hydrogen energy com­piled by the National Research Institute, please contact as fol­lows.

Ministry of International Trade and Industry Agency of Industrial Science and Technology New sunshine Project Promotion Headquaters

Tel : +81-3-3501-9471 Fax: +81-3-3501-9489

Person in charge : Ms. Hamaguchi

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