Cutting the cost of capturing CO2

A project funded by the European Union and led by SINTEF, the Norwegian research organisation, with ten other European partners aims to demonstrate a cost-effective CO2 capture technology that could herald a new generation of power-generation plants with integrated CO2 capture.

Power generation based on fossil fuels is one of the major contributors to global CO2 emissions. Measures have been taken at both national and European levels to reduce CO2 emissions from power stations as we move towards a low-carbon future.

The DemoCLOCK project, with a budget of €8.2 million, is based on a special version of a technology called Chemical Looping Combustion (CLC). This new CO2 capture technology is believed to be cost-effective and has already been tested in the laboratory with promising results.

“CLC itself is believed to be on the verge of becoming one of the most cost-effective ways of capturing CO2 from power plants. DemoCLOCK aims to demonstrate the technical, economic and environmental feasibility of implementing a packed bed-based chemical looping combustion (CLC) concept in large-scale power plants. This version of CLC is even less complex and more compact than the original CLC concept,” says Dr Shahriar Amini of SINTEF, who is the project coordinator of DemoCLOCK.

Building a test reactor in Spain

All the partners in the DemoCLOCK project will work towards the proof of feasibility: the medium-scale demonstration of a 500kW packed bed CLC reactor in the Elcogas company’s Integrated Gasification Combined Cycle (IGCC) power plant in Puertollano in Spain, the largest IGCC power plant in Europe.

SINTEF, Eindhoven University of Technology (TU/e), the Flemish Institute for Technological Research (VITO) and the Energy Research Centre of the Netherlands (ECN) will test the materials to be used in the reactors. Céramiques Techniques et Industrielles (CTI) will undertake large-scale fabrication of the materials; SINTEF will lead the conceptual design phase and collaborate with TU/e to deliver an optimised reactor performance; Array Industries will take care of the detailed engineering design, construction and integration of the demonstration plant in Puertollano, which will be operated by ECN and Array Industries.

In order to ensure that all health, safety and environmental aspects are taken into account in the design, construction and operation of the reactor, the Institute for Ecology of Industrial Areas (IEIA), Verbia Nano Technologies and VITO will perform environmental impact and waste management assessments.

The implementation plan will be led by Politecnico di Milano in collaboration with Foster Wheeler Italiana, in order to confirm the technical and economical feasibility of integrating the process into large-scale power generation.

The commercialisation phase will be led by Foster Wheeler Italiana, and the entire project will be coordinated by SINTEF.

The original CLC concept

Fossil fuel power generation is based on burning fuel with oxygen from the air, just as we burn wood in a fire. The resulting CO2 is diluted in large amounts of nitrogen left over from the air, which makes it very difficult to economically separate, capture and store.

CLC overcomes this problem by never allowing direct contact between the air and the fuel, so that the CO2 does not mix with nitrogen in the first place. Two reactors, an air reactor and a fuel reactor, are used in the CLC process, and an oxygen carrier in the form of metal oxide granules is circulated between them. In the air reactor, oxygen from the air is transferred to the oxygen

DemoCLOCK participants:

(DemoCLOCK: Demonstration of cost-effective medium-size Chemical Looping Combustion through packed beds using solid hydrocarbons as fuel for power production with CO2 capture)

n SINTEF, Norway n Politecnico di Milano, Italy n Verbia Nano Technologies, Spain n Flemish Institute for Technological Research (VITO), Belgium n Elcogas, Spain n Energy research Centre of the Netherlands, (ECN), the Netherlands n Institute for Ecology of Industrial Areas (IEIA), Poland n Foster Wheeler Italiana, Italy n Céramiques Techniques et Industrielles (CTI), France n Array Industries, the Netherlands n Eindhoven University of Technology (TU/e), the Netherlands

carrier in a process called oxidation, producing lots of heat and a harmless stream of oxygen-poor air. The resulting oxygen-rich oxygen carrier is then transferred to the fuel reactor, where it provides the fuel with oxygen in the total absence of nitrogen.

Fuel reacts with the oxygen carrier in a process called ‘reduction’ and produces an exit stream of only CO2 and H2O. Capturing the CO2 from this stream is very easy because it only needs to be cooled down for the H2O to condense out, leaving a stream of pure CO2. The oxygenpoor oxygen carrier can then be transported back to the air reactor to repeat the process. As in any other fossil fuel power generation system, the heat generated in the reactors can be converted to electricity by means of turbines. The DemoCLOCK version of CLC – ‘packed bed’

In packed bed CLC, the oxygen carrier material is fixed in a reactor and alternatively exposed to fuel gas and air streams. This arrangement essentially creates the fuel reactor and the air reactor alternatively in a single reactor and therefore has all the CO2 capture advantages of the standard CLC process described above.

Another major advantage of this setup is that the oxygen carrier material no longer has to be transferred between the two reactors. This greatly simplifies the process and is expected to speed up its commercialisation. The packed bed CLC concept was originally developed by a research group at Eindhoven University of Technology in the Netherlands (formerly at the University of Twente in the Netherlands).

The packed bed CLC will be used to convert gasified solid hydrocarbons (syngas) into hot streams of CO2 and oxygen-poor air which can potentially be used for electricity generation. Packed bed reactor technology thus opens up the prospect of using various types of fuel (e.g. coal, petcoke, biomass).

“In comparison with currently available CO2 capture techniques, our concept will reduce power generation energy losses and do so in a cost-effective way,” says project coordinator Shahriar Amini.

The project aims to modify the current energy generation system to make it more sustainable and less dependent on imported fuels. This will help to address pressing challenges of security of supply and climate change, while increasing European industrial competitiveness. n