news / 2011-02-17

From exhaust gas to raw material

Can CO2 be put to good use?

CO2 is a nutrient for algae. In Germany's first pilot plant for CO2 capture by microalgae, the microalgae grow ten times more quickly on flue gases from the Niederaußem coal-fired power than land plants do. ©RWE

CO2 is all around us, and many consider it to be problematic from a climate perspective. It would be ideal if a use for this "climate killer" could be found. However, the concrete areas of application and potentials for CO2 are largely unknown outside of the specialist community. At a symposium held in Düsseldorf on 21 September 2010, the German Federal Ministry of Education and Research and the energy company RWE examined the issue of how CO2 can be used as a raw material in new products instead of allowing it to escape into the atmosphere.

 

With its support programme called "Technologies for sustainability and climate protection – Chemical processes and material use of carbon dioxide", the German Federal Ministry of Education and Research is helping scientists and industry to work together to develop innovative processes. Total funding of 100 million euros has been approved for this programme by 2014.

 

The capture and use of CO2 from industrial plants or power plants (Carbon Capture and Usage, or CCU for short) is an unconventional approach that will hopefully contribute to climate protection in the future. CO2 can be used as a technical gas or else converted in biotechnology, biology and chemistry applications where it serves as a carbon building block.

 

Thomas Rachel, Parliamentary State Secretary in the German Federal Ministry of Education and Research, would like to see CO2 shake off its bad image. Speaking before an audience of around 70 researchers and politicians, he emphasised that the use of CO2 is by no means the perfect solution to climate problems, but that it does have a contribution to make here. Up to one percent of CO2 emissions could be stored in high-quality products, and as much as 10 percent in fuels. A number of approaches are being pursued in parallel here, with the aim of ensuring that Germany is a technology leader in the international competitive arena.

 

For example, RWE is working together with Jacobs University Bremen and Forschungszentrum Jülich to "feed" algae with CO2 from the flue gases of a coal-fired power plant in a breeding plant that is around 600 m2 in size. The algae use the climate gas as nutrients and can then serve as biomass in the production of biogas. The fact that this plant can only bind a few tonnes of CO2 per annum is evidence of the minor role of CCU technologies in quantitative terms.

 

On the other hand, researchers such as Prof. Dr. Walter Leitner from the Institute for Technical and Macromolecular Chemistry at RWTH Aachen University highlight the scientific challenge of using the carbon in CO2 to develop a chemical feedstock that could reduce dependency on oil for many products. 107 megatonnes of CO2 are already being used in fertiliser production every year. CO2 will soon be a component in plastics such as polyurethane which, when used in insulation technology, will save heating energy and thus also CO2. The "Catalytic Center" in Aachen is already drumming up enthusiasm now among young researchers for this "dream technology" that will be ready for industrial applications by 2015, according to Prof. Leitner. Special catalysts still need to be developed for CO2, which displays slow reaction kinetics.

 

CO2 can help to store energy

The latest joint project, "Co2rrect – Use of CO2 as a carbon building block using predominantly renewable energy", sees researchers tackling two problems at once: On the one hand, a lot of energy needs to be consumed to convert CO2 into other forms. For example, synthesis reactions with hydrogen from renewable production could be used to produce various carbon building blocks, which could then serve as fuels or as intermediate products in plastics production. In this way, CO2 could end up in household products or in DVDs. On the other hand, renewable energy sources such as solar and wind power do not provide a constant supply of electricity. However, the chemical industry generally requires a constant supply in order to operate its processes reliably. The aim of this research project is thus to develop processes for hydrogen production and for the conversion of CO2 into carbon monoxide or formic acid, for example, on an industrial scale in such a way that these processes would also run in a robust manner with a fluctuating supply from renewable energy sources. Required here are new technological developments and, in addition, new models for the interplay of the energy sector and the chemical industry.

 

The partners in "Co2rrect“ are: Bayer Technology Services GmbH; RWTH Aachen University; Technical University of Dresden; University of Stuttgart; Technical University of Darmstadt; Technical University of Dortmund; Ruhr University of Bochum; Leibniz Institute for Catalysis at the University of Rostock; Max Planck Society (MPG); Karlsruhe Institute for Technology (KIT); Bayer MaterialScience AG; INVITE GmbH; RWE Power AG; and Siemens AG.

Projects currently being funded