LOGO

Production

Production from hydrocacbon

Steam methane reforming(SMR): • This is today's most efficient method for the production of

synthesis gas CO + H2. With raw material is natural gas should be

applied in the gas sources such as the U.S., Saudi Arabia. In addition, the source of naphtha is to be used in Europe.

• The reactions:

Besides natural gas, naphtas are also used as raw materials:

• Generally, a nickel catalyst is used for the reaction, loaded to an alumina base material at 10–15 wt%. Besides nickel, platinum and ruthenium are also used as catalysts.

Production from hydrocarbon

Partial Oxidation (POX):

This process can be used with diverse materials, from gases, liquids and even solids

such as coal.

The reactions:

POX can easily be performed without the presence of a catalyst. High temperatures

of 1200–1450°C and pressures of 3 –7.5 MPa (Texaco process) are needed to

ensure high conversion rates.

The catalytic partial oxidation (CPO) reaction, however, can take place at lower

temperatures and may lead to a significantly enhanced H2 yield from the fuel

Production from hydrocarbon

Coal Gasification

During World War II, the syngas is produced by this

method for the production of gasoline. At present,

hardly used due to its high price. However in some

coal-rich countries such as South Africa, it was

maintained. The reactions:

Then CO is converted to CO2 and H2:

Production from hydrocarbon

LOGO Water Electrolysis

Electrical energy input∆G = 237.13 kJ

Energy from environmentT∆S = 48.7 kJ

Energy exchange the processes for one mole of water ∆H = 285.83 kJ

Perry's Chemical Engineers' Handbook, Section 2.Physical and Chemical Data

Electrolysis of water is the decomposition of water (H2O) into oxygen (O2) and hydrogen gas (H2) due to an electric current being passed through the water.

Alkaline electrolysis

- Alkaline electrolyte electrolyzers represent a

very mature technology that is the current

standard for large-scale electrolysis.

Common electrolyte: aqueous potassium

hydroxide (KOH) at 30% concentration

Operation Conditions: 70-100oC and 1- 30bar

Operational voltage: 1.7-2.2 V

Current density: 0.2-0.6 A/cm2

Electricity Consumption: 4.2 – 5.6 kWh/Nm3

Can utilize cost effective electrode

materialsDiaphragm often asbestos

Efficiency: 70-80% (based on hydrogen HHV) [1]

Russell H. Jones & George J. Thomas, “Materials for the Hydrogen economy”, 2008, p.40

PEM Electrolysis [1]

Polymer electrolyte water electrolysis (PEWE) uses a polymer electrolyte membrane as a medium of ion transfer instead of solution electrolyte in AWE. This method is often called polymer electrolyte membrane or proton exchange membrane (PEM) water electrolysis, too.

Operational principle The water flows from the plate to the

anode through the current collector, and reacts to make protons.

Current collectors are porous conductors that allow electrons to transfer from electrode to outer circuit and allow reactant gas from bipolar plate to electrode.

The protons are transported through the PEM to cathode side, and hydrogen is generated at the cathode.

The PEM also works as a separator of product gases.

[1] Seiji Kasahara et al., “Water electrolysis” in

“ Nuclear hydrogen production handbook”, 2011

Advantages

Corrosive liquid electrolyte is not required

Construction of facility is easy

No electric resistance by gas bubbles between electrodes can be made.

Purity of product gas is high

Disadvantages

Components should be corrosion resistant due to strong acidity of the PEM.

Uniform contact between the PEM and the electrodes should be achieved

Cost of the PEM, electrodes and current collectors is high

PEM Electrolysis

Steam electrolysis[1]

The process of the high-temperature electrolysis (HTE) of steam is a reverse reaction of the

solid-oxide fuel cell (SOFC): an oxygen ionic conductor is usually used as a solid-oxide

electrolyte.

The electrical energy demand, ΔG, decreases with increasing temperature. The ratio of ΔG to

ΔH is about 93% at 100°C and about 70% at 1000°C

An assembly unit consisting of 15 cells

Outer diameter: 12mm

Active area: 75 cm2

Hydrogen production rate: 100 NL/h.

Operation Conditions: 800oC

Operational voltage: 1.3 V

Current density: 0.45 A/cm2 [1] Seiji Kasahara et al., “Steam electrolysis” in

“ Nuclear hydrogen production handbook”,

2011

Photoelectrolysis

Photoelectrolysis involves splitting water directly into hydrogen (H2) and oxygen (O2) using the energy of sunlight.

The reactive decomposition occurs at 1.23 V, so the minimum bandgap for successful water splitting is 1.23 eV, corresponding to light of 1008nm. [2]

Operational principle [3]

TiO2 electrode electrowas irradiated with light consisting of wavelengths shorter than 415 nm (3.0 eV), photocurrent flowed from the Pt electrode to the TiO2 de through the external circuit.

The direction of the current revealed that the oxygen occurs at the TiO2 electrode and the hydrogen occurs at the Pt electrode.

This observation shows that water can be decomposed, using UV light, without the application of an external voltage.

Technical Target: Photoelectrochemical Hydrogen Production *Characteristics Unit 2003 Status 2006 Status 2013 Target 2018 Target

Usable semiconductor bandgap

eV 2.8 2.8 2.3 2.0

Chemical conversion process efficiency (EC)

% 4 4 10 12

Plant solar-to-hydrogen efficiency (STH)

% Not availble Not availble 8 10

Plant durability Hr Not availble Not availble 1000 5000

* Todd G. Deutsch & John A. Turner , Semiconductor Materials for Photoelectrolysis , May 16th, 2012 , p.3

Photoelectrolysis

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• Small system size

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• Low efficiency

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This GaInP2 /GaAs multiple-band-gap photoelectrochemical cell uses only illumination and can generate hydrogen at greater than 12% conversion efficiency.

Photobiological hydrogen

Microalgae and cyanobacteria are photoautotrophic organisms because they

can use light as the energy source and the carbon dioxide as carbon source

Under anaerobic conditions, microalgae can produce H2, by water photolysis,

using light as the energy source. The catalyst is a hydrogenase, an enzyme that

is extremely sensitive to oxygen, a by-product of photosynthesis.

Photobiological hydrogen

• The photosynthetically active radiation

(400–700 nm for green algae, and 400–

950 nm for purple bacteria) or on the full

solar irradiance (all wavelengths).

• In the Netherlands, 420 h would be

needed for the production of 1 GJ of

hydrogen per year. In southern Spain,

this would be 250h.

LOGO

An application-specific issue.

Hydrogen Storage

Physical storage of H2

Chemical storage of hydrogen

New emerging methods

Hydrogen Storage Overview

Compressed

•Volumetric and Gravimetric densities are inefficient, but the technology is simple, so by far the most common in small to medium sized applications.•3500, 5000, 10,000 psi variants.

Liquid (Cryogenic)

•Compressed, chilled, filtered, condensed•Boils at 22K (-251 C).•Slow “waste” evaporation•Kept at 1 atm or just slightly over.

•Gravimetrically and volumetrically efficient but very costly to compress

Metal Hydrides (sponge)

•Sold by “Interpower” in Germany•Filled with “HYDRALLOY” E60/0 (TiFeH2)•Technically a chemical reaction, but acts like a physical storage method•Hydrogen is absorbed like in a sponge.•Operates at 3-30 atm, much lower than 200-700 for compressed gas tanks•Comparatively very heavy, but with good volumetric efficiency, good for small storage, or where weight doesn’t matter

Carbon Nanofibers

Complex structure presents a large surface area for hydrogen to “dissolve” into

Early claim set the standard of 65 kgH2/m2

and 6.5 % by weight as a “goal to beat”

The claim turned out not to be repeatable

Research continues…

Methanol

Broken down by reformer, yields CO, CO2, and H2 gas.

Very common hydrogen transport method Distribution infrastructure exists – same as

gasoline

Ammonia

Slightly higher volumetric efficiency than methanol Must be catalyzed at 800-900 deg. C for hydrogen

release Toxic Usually transported as a liquid, at 8 atm. Some Ammonia remains in the catalyzed hydrogen

stream, forming salts in PEM cells that destroy the cells

Many drawbacks, thus Methanol considered to be a better solution

Alkali Metal Hydrides

“Powerball” company, makes small (3 mm) coated NaH spheres.

“Spheres cut and exposed to water as needed”

H2 gas released

Produces hydroxide solution waste

Sodium Borohydrate

Sodium Borohydrate is the most popular of many hydrate solutions

Solution passed through a catalyst to release H2

Commonly a one-way process (sodium metaborate must be returned if recycling is desired.)

Some alternative hydrates are too expensive or toxic The “Millennium Cell” company uses Sodium

Borohydrate technology

Amminex

•Essentially an Ammonia storage method•Ammonia stored in a salt matrix, very stable•Ammonia separated & catalyzed for use•Likely to have non-catalyzed ammonia in hydrogen stream •Ammonia poisoning contraindicates use with PEM fuel cells, but compatible with alkaline fuel cells.

Amminex

•High density, but relies on ammonia production for fuel.

•Represents an improvement on ammonia storage, which still must be catalyzed.

•Ammonia process still problematic.

Diammoniate of Diborane (DADB)

So far, just a computer simulation.

Compound discovered via exploration of Nitrogen/Boron/Hydrogen compounds (i.e. similar to Ammonia Borane)

Thermodynamic properties point towards spontaneous hydrogen re-uptake – would make DADB reusable (vs. other borohydrates)

Solar Zinc production

Isreli research effort utilizes solar furnace to produce pure Zinc

Zinc powder can be easily transported

Zinc can be combined with water to produce H2

Alternatively could be made into Zinc-Air batteries (at higher energy efficiency)

Alkaline metal hydride slurry

SafeHydrogen, LLC Concept proven with Lithium

Hydride, now working on magnesium hydride slurry

Like a “PowerBall” slurry Hydroxide slurry to be re-

collected to be “recycled” Competitive efficiency to Liquid

H2

Storage Method Comparison

Sodium Hydride slurry .9 1.0 Must reclaim used slurry

DADB .1 - .2 .09-.1 (numbers for plain “diborane”and sodium borohydride, should be similar)

Amminex 9.1 .081

Zinc powder unsure

US DOE goal 9.0 .081