A vital instrument in the fight against climate change As part of the fight against climate change, CCS technology (Carbon Capture and geological Storage) is considered to be a solution that is necessary to lower CO2 emissions attributable to human activities. Today, these emissions stand at 30 billion tonnes per year, of which only half is naturally captured by oceans, soil and forests. A total of 22% of the world’s CO2 emissions come from transport and 66% come from industrial facilities (fossil-fuel power plants, iron and steel plants, cement works, refineries, etc.). All scenarios, including those of the International Energy Agency (IEA) and of the European Union, rely on CCS to help lower CO2 emissions. France, for example, has committed itself to dividing its emissions by four by 2050 compared with 1990. CCS is practically the only solution that can lower the emissions of industrial facilities.

THANKS TO CO2 CAPTURE, FLUE GASES EMITTED BY INDUSTRY AND POWER PLANTS DO NOT CONTAIN CO2

With regards to electricity production, attention is placed in particular on coal. As the rate of capture envisaged is generally 90%, a power plant that meets current performance standards and is supplied with international-grade coal would see its emissions fall from around 850 to 230 gCO2/kWhe (these figures include emissions associated with the coal extraction and procurement process).

Carbon capture aims to trap carbon dioxide and stop it from being released into the atmosphere through an industrial process that makes use of innovative technology. The carbon dioxide is then compressed and transported through a pipeline or by ship to deep geological formations with suitable characteristics, particularly in terms of containment, into which it is injected. The EDF Group stands out among electricity producers thanks to a carbon intensity of less than 100 gCO2/kWhe (compared to an average of 346 gCO2/kWhe in Europe) due to its nuclear power plants in France and the UK. Never theless, the Group cont inue s to proac t i ve ly reduce i t s emiss ions through a CCS programme that has been in place since 2007 and brings together p r o d u c t i o n , t h e r m a l engineering, research and development, and subsidiaries. Its aim is to ensure that the Group has a comprehensive view of technological changes and costs so that it can prepare itself as well as possible with regards to choices which will have to be taken in the future.

EDF R&D FEBRUARY 2013 innovation.edf.com

Technologyunveiled

CO2 capture

CO2 emissions from coal

Le Havre thermal power plant

Existing capture technology is based on several demonstration projects. An assessment of the energy performance of this technology, based on pilot results and extrapolated to a scale of 1:1 using simulation tools, does not currently reveal any major differences.

Capture technologyThere are three types of technology:• Post-combustion is the most mature.

CO2 is captured in fumes resulting from the combustion process (hence the term, ‘post-combustion’). Post-combustion absorption in a chemical solvent consists of separating CO2 from the other gases present in the fumes released by the boilers. Similar technology has in fact been used for around 50 years by the oil and gas industry to separate CO2 that is naturally present in certain natural gas reservoirs. The application of this technology to electricity production or to other industrial sectors would require a research, development and demonstration phase as the fumes emitted by these sectors are more difficult to process than natural gas. The development of the two other types of technology is less advanced.

• Oxy-combustion involves burning coal in the presence of pure oxygen (not air) to ensure that the fumes only contain CO2 and water, thereby faci l i tat ing the removal of CO2. Combustive oxygen is obtained by separating oxygen and nitrogen from the air using a cryogenic process.

• Pre-combustion is based on the prior gasification of coal, which produces a mixture of CO2 and hydrogen, and then the conversion of this mixture in the presence of water vapour to obtain CO2 and hydrogen, followed by the pressurised separation of CO2.

From pilots to demonstratorsThere are tens of industrial pilots in operation (on a scale of between 1:1000 and 1:100). Demonstrators (units which are almost industrial in size and are required to confirm industrial costs) constitute the next stage. The European Union intends to contribute to the funding of two or three industrial CCS demonstrators. Others are planned in the US, China, Australia and the Middle East. Due to funding difficulties caused by the current economic downturn, this industrial demonstration stage has fallen behind schedule. In France, Total operates in Lacq a gas-fired boiler that allows up to 10 tonnes of CO2 to be captured per hour using the oxy-combustion method. In Le Havre, EDF is testing an advanced form of technology on fumes emitted by a coal-fired unit.

Post-combustionCa p t u r i n g CO 2 u s i n g c h e m i c a l absorption is based on CO2 separation from the flue gas using an amine aqueous solution. The fumes, from which par ticles and nitrogen and sulphur oxide have been removed, are cooled (to around 45°C) before entering a column which maximises liquid/gas contact (thereby facilitating

HOW DOES IT WORK?

ONE GOAL: LIMIT THE GREENHOUSE EFFECT

KEY POINTS

Global greenhouse gas

emissions

Under its ‘business as usual’

scenario (an average increase

in temperature of +6°C), the

IEA predicts that the world

will emit 58 billion tonnes

of CO2 in 2050 (double the

emissions of 2009). The

share of fossil-fuel electricity

production would continue

to make up around 40%

of these emissions.

Under the ‘+2°C’ scenario,

emissions in 2050 fall to

around 16 billion tonnes of

CO2. CCGS accounts for just

under 20% of this reduction,

shared equally between

electricity production (coal,

gas) and industry (steel

works, cement works,

refineries, etc.).

The share of fossil-fuel

electricity production would

fall to around 15%.

Emissions of a coal-fired

power plant

A current pulverized-coal

power plant (net efficiency =

45%) with an output of 800

or 1,000 MWe emits around

550 tonnes of CO2/h or 700

tonnes of CO2/h

(direct emissions).

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Three ways to capture CO2

Carbon capture pilot, Le Havre plant

the transfer of CO2 between ascending fumes and descending solvent) while limiting the fumes’ loss of pressure. At the bottom of the absorption column, solvent which contains CO2 is pumped up to the head of the regeneration column where the pressure and temperature conditions (2.5 bar, 120°C) allow the CO2 to be desorbed; the CO2 is then compressed after a dehydration stage. At the bottom of the regeneration column, solvent that contains a small amount of CO2 is returned to the top of the absorption column to absorb more CO2. The heat necessary to keep the regeneration column at the right temperature is taken from the coal-fired power plant’s steam cycle. This extracted steam, which no longer completely fulfils its role in the turbine, lowers the amount of electricity produced. This is the main factor behind the energy penalty associated with a carbon capture unit integrated to a power plant.

Oxy-combustionA cryogenic unit that removes gases from air typically produces oxygen that

is 95% pure. This combustive oxygen is mixed with a large share of the combustion fumes (made up of water and CO2). The mixture is recycled and injected into a boiler to control combustion. As the atmosphere in the boiler differs from combustion in the open air, corrosion problems are more significant. Nothing more than condensation is used to separate the CO2 from water. A CO2 purification stage, which takes place during compression, is still necessary. In the case of oxy-combustion, the energy penalty is mainly attributable to the energy consumption of today’s O2 production processes.

Pre-combustionThis more complex method, which involves IGCC plants (prior gasification of coal), appears to be less interesting. Hydrogen is burned on its own to produce electricity in a combined cycle (or used in other industrial applications). Once captured, the CO2 is dehydrated and compressed in a unit so that it may be packaged for transport.

unveiledTechnology

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DID YOU KNOW?

EDF and ALSTOM, with

the support of ADEME,

are developing a post-

combustion CO2 capture

research demonstrator at the

Le Havre power plant. EDF

is coordinating the entire

project. ALSTOM is in charge

of process research and

construction. Dow Chemical

supplies the solvent that is

being tested. The pilot will

be operated and the results

will be jointly interpreted by

EDF and ALSTOM in 2013. The

tests will be used to validate

the energy and environmental

performance of this process

(lower consumption of energy

and solvent, etc.) and its

flexibility when in operation.

Various road maps are counting on the fact that this technology will be commercially available as from 2020. As the industrial demonstration stage is behind schedule, the first full-scale units are expected to be built in around 2025. The next few years will be decisive in terms of development planning. The key problem posed by existing capture technology is its impact on the power plant’s output: today, it is reduced by 15% to 25% when compared with a power plant that does not capture CO2, thereby almost doubling the cost of the electricity produced. Furthermore, more than ever before, fossil -fuel power plants will have to be flexible, adapt their output to instantaneous demand and complement an ever-increasing number of power plants fed by intermittent renewable sources (wind, solar). Several points still need to be val idated to guarantee the flexibility of a power plant with CCS. Flexibility could differ, in particular, in accordance with the capture technology selected. Improvements are necessary to

control these challenges. In addition to programmes that aim to improve current capture processes, EDF is also working on innovative disruptive processes which are less advanced but whose energy performance promises to be far better. These processes include, for example: non-aqueous solvents, membranes, adsorption and chemical looping. The future of this technology will also depend on the price of a tonne of CO2. Today, the development and deployment of CCS technology are hindered by non-technical barriers. With regards to carbon capture, these include:• funding mechanisms, which are

insufficient for the demonstrators and not stable enough over time,

• the high financial risk of projects, • the env i ronmenta l cha l l enges ,

specific to each form of technology, wh i ch a re s t i l l b e ing s tud i ed ,

• t h e i n v o l v e m e n t o f i n d u s t r y t o m a n u f a c t u r e t h e m a i n component s and consumables .

Fabrice Chopin, CCS project manager, EDF R&DNicolas Vaiss iere, programme manager, EDF R&D

Amine: an organic compound derived from ammonia by replacement of one or more hydrogen atoms by an organic group. Amines are widely used in industry.

CCS: Carbon (CO2) Capture and geological Storage.

EEPR: European Energy Programme for Recovery.

Direct emissions: CO2 emitted during combustion; emissions attributable to the fuel’s extraction and procurement stages are not considered.

Specific emissions: quantity of CO2 emitted during the production of a kWh of electrical energy, expressed as gCO2/kWhe.

GHG: Greenhouse gas. Water vapour is the main natural GHG. CO2 is the main and the most widely known man-made GHG. However, other gases have a higher global warming potential, even though they are released into the atmosphere in far smaller quantities: methane (23 times the 100-year global warming potential of CO2), nitrous oxide (310 times), industrial fluorinated gases (CFC, etc. - 1,000 to 1,700 times).

IGCC: Integrated Gasification Combined Cycle. A power plant made up of a coal gasification unit coupled with a combined cycle.

NER300: New Entrants Reserve. A European fund that supports the energy sector. NER300 funds may be used for demonstration operations involving innovative renewable energy and CCS projects. As the price of a tonne of CO2 on the European market collapsed, the NER300 programme’s budget was significantly reduced in 2011/12.

Energy penalty: the energy necessary to capture a given amount of CO2. For power plants, it is expressed as a percentage reduction of the plant’s efficiency to capture 90% of the CO2 contained in the flue gases.

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www.edf.fr

Please do not print this document unless you need to. EDF R&D publication - 1 av Général de Gaulle 92141 Clamart CedexPublishing Director: Stéphane Andrieux Editorial secretary: Florence Metge-LaymajouxThe author, not EDF, is responsible for the content of this publication.

© 2013 EDFReproduction is forbidden without authorisation from the author.Photo credits: EDF, Marc Didier - Guy Castellanc and Yann Le Moullec.

The EDF Group is ISO 14001 certified.

> for more information In FranceClub CO2: http://www.captage-stockage-valorisation-co2.fr/

In EuropeZEP (Zero Emission Platform): http://www.zeroemissionsplatform.eu/

InternationalIEA (International Energy Agency): : http://www.iea.org/topics/ccs/

unveiledTechnology

Contact:

communication-rd@edf.frhttp://innovation.edf.com

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