Spain pioneers pre-combustion carbon capture

Pedro Casero of ELCOGAS in front of the designated lot of the world’s first pre-combustion carbon dioxide capture plant. The plant will be integrated with an existing IGCC plant in Puertollano, 200 km south of Madrid.

Pedro Casero of ELCOGAS in front of the designated lot of the world’s first pre-combustion carbon dioxide capture plant. The plant will be integrated with an existing IGCC plant in Puertollano, 200 km south of Madrid.

The world’s first plant capturing CO2 prior to combustion in a thermal power plant is to be commissioned during the first half of 2009. The 14 MWt pilot plant will be integrated with an existing power plant, ELCOGAS in Puertollano, Spain, and will capture 35 000 tons of CO2, while producing 700 tons of pure H2 annually.

Bellona recently visited ELCOGAS in Spain to learn about the plans. The plant will most likely be the world’s first carbon dioxide capture plant applying the so-called pre-combustion technology. This technology involves removal of CO2 prior to the combustion of fossil fuels. Read more about various carbon capture technologies here.

A budget of €18 500 000 is being provided partially by the state and regional governments, partially by the industrial owners of ELCOGAS (ENDESA, EDF, Iberdrola, Hidrocantábrico, ENEL, EDP, Siemens, BWE, and Krupp Koppers).

The project is part of a national strategic research program, released by the Ministry of Education and Science, called PSE-CO2 (www.ciemat.es), aiming to develop and demonstrate the technical and commercial feasibility of large-scale Carbon dioxide Capture and Storage (CCS).

A plan for full-scale CCS at the plant has yet to be made.

High power efficiency

The ELCOGAS plant is of the Integrated Gasification Combined Cycle (IGCC) type. IGCC is a modern thermal power plant technology, and ELCOGAS is one of four existing IGCC plants worldwide. The plant has been operated commercially since the mid-90s. At the same time, the plant is considered research infrastructure and has been allowed flexible terms for feeding power to the grid.

The plant’s installed capacity is 335 MW (ISO) and achieves a net efficiency of 42.5 per cent, 10 to 15 per cent higher than existing conventional thermal power plants. As the technology matures, efficiencies above 50 per cent are expected of IGCC plants.

Biomass combustion

Another advantage of the IGCC concept is its high fuel flexibility. In addition to the conventional fuels, coal of various quality and petroleum coke, IGCCs can utilize biomass and waste for fuel. Biomass combined with carbon capture would result in a negative net climate effect; it would remove CO2 from the atmosphere.

The first step of the IGCC process is converting the solid fuel to synthesis gas (gasification), a mixture of hydrogen and carbon monoxide (CO). Particles and sulphur are removed from the gas, partially to be sold as raw materials for other industries. The synthesis gas is then undergoes combustion in a gas turbine, generating electric power.

Heat generated during gasification and combustion is used to generate steam, which subsequently runs a turbine to generate more power. This combination of gas and steam turbines is the origin of the term combined cycle, a concept often used in modern natural gas power plants.

Mature technology

The CO2 capture plant is currently under detail engineering, and construction is due to start in the middle of 2008. The chosen concept is solely using commercially available technology.

The first process modification is running the synthesis gas through a so-called water-gas-shift (WGS) reactor. This reforms the gas to a gas mixture consisting of about 50 per cent hydrogen and 39 per cent carbon dioxide, which combined with a pressure of 16 bar provides ideal conditions for CO2-capture.

Various technologies are commercially available for separating CO2 from hydrogen, as this separation is common in ammonia plants. For this first pilot plant, Linde Gas is contracted to deliver a turnkey chemical absorption plant, utilizing an amine as absorption fluid.

Amine absorption is currently the most mature of the contending technologies for capturing CO2. Other technologies, such as solid adsorbents and membranes, are however also under development. To facilitate development of these novel concepts, the ELCOGAS CO2-capture project welcomes cooperation with technology developers on testing and demonstration.

Hydrogen

Product flexibility is yet another advantage of the IGCC technology. Besides generating electric power by combusting the synthesis gas, the process is well-suited for producing hydrogen.

The introduction of CO2-capture enhances this possibility, as it provides a gas rich (80 per cent) on hydrogen. Pure hydrogen already has a wide array of industrial applications, and could play an enabling role as an energy carrier in making the transport sector climate neutral.

Cooperation with China

The experience from the IGCC plant in Puertollano lays a solid foundation for international cooperation. Among other things, ELCOGAS expertise is contributing to realizing the first IGCC plant with CO2-capture in China, the GreenGen project.

China’s power generation is dominated by coal power (80 per cent), and has grown by 12-15 per cent annually since 2003. In 2005 alone, capacity grew by 70 GW, equivalent to the total installed capacity of Great Britain. This development has made China the world’s largest emitter of greenhouse gases.

Heavy emissions of SOx, NOx and particles from conventional coal power plants close to city centers are also a main issue for the air quality of Chinese cities. The IGCC technology cuts these emissions to the level of natural gas power plants, and to one tenth of state-of-the-art Pulverized Coal plants.