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Trading Carbon : November 2011
43 CARBON CAPTURE AND UTILISATION using the gas for CCU rather than storing it underground can add value, as well as offsetting some of the CCS costs. The economic potential of CCU is limited by scale, but some options are attractive enough to pursue. Mainland Europe, particularly Germany, the US and Australia are well advanced in research and development of CCU technologies. Substantial investment has been made in those countries by extending CCS technology to incorporate utilisation in addition to storage. New data are emerging daily and so any current analysis reflects a snapshot of a point in time. In February, the Danish government stated that it will aim to go to a zero-fossil fuel energy economy by 2050. CCU could play a part in achieving that aim. The policy document looks at the pros and cons of CCU globally and discusses opportunities for implementation in the UK in three areas: chemical conversion, mineral carbonation and biofuels from algae. In the majority of cases there will be an energy penalty as a result of the thermodynamics and the process. It is clear that in order to be economically viable there needs to be a whole systems approach and key to this is the integration of renewable energy supplies, such as wind and solar. Rather than treating CO2 as waste, it can be regarded as a chemical feedstock for the synthesis of other chemicals that do not rely on a petrochemical source. The energy required for this would be best facilitated by renewable energy. New catalysts are also necessary. Indeed the feeling is that catalysis will be crucial to development. This process can build on current post-combustion CCS technologies to give value- added products that can, in theory, offset the costs of plant investment or even make the process profitable. Currently, pilot scale technologies only take a slipstream from the main flue gas supply, but have the potential and economic viability to be scaled up. Continuous flow reactor technology and the development of new active and selective catalysts will need to be developed if this CCU option is to play a role at a commercial scale. "What is clear is that chemical synthesis will only use a small fraction of the CO2 produced as other chemicals will be required as co-reactants and importantly the global chemicals capacity is lower than the scale of emissions," said Styring, who also chairs the CO2chem.com network, a UK research council project aimed at developing a community towards a sustainable chemical feedstock supply by 2050. Mineral carbonation involves the reaction of minerals with CO2 to form inert carbonates. The carbonates can be used as construction materials. Since the energy state of magnesium and calcium carbonates is lower than CO2, theoretically, the process requires no energy and could also generate heat. The current bottleneck, however, for a viable mineral carbonation process on an industrial scale is the reaction rate of carbonation. To enhance reaction rates, heat, pressure, chemical processing and mechanical treatment (grinding) of the mineral could be applied, but these treatments are expensive -- ¤60 ($83)--¤100/ tonnes of CO2 stored -- cost energy and lead to environmental impacts. The potential, globally and in the UK, is considered large, but the technology is in the research and development (R&D) phase. Microalgae have a high biomass productivity compared with terrestrial crops and can be cultivated on non-arable land. Many species grow in salty water. These characteristics could enable sustainable manufacture of products such as bio- oils, chemicals, fertilisers and fuels. Using flue gases as nutrient supply and CO2 source, the cultivation of microalgae in open ponds or photobioreactors could directly capture and utilise CO2. Per tonne of algae biomass, approximately half a tonne of carbon -- from 1.8 tonnes of absorbed CO2 -- can be fixed and converted. Microalgae technology is in the R&D phase, and not yet ready for commercial implementation. To achieve cost and energy requirement reductions, leading to viable large-scale algae production, significant R&D investments are needed. For the UK as an industrialised country, all CCU options could be relevant. Given its business-oriented academic community, the UK could play a role and benefit from the commercialisation of the technologies involved. If CCU was to be considered in the UK, policymakers should take note of the supply chain of energy and co- reactants to a broad portfolio of products, and develop an appreciation of the market demands for such products. Depending on the process and products, CCU can be profitable with short payback times on investment. What can UK policymakers do to enable CCU? A first step would be for the government to invest in CCU R&D. Through a strategic policy group, investors could be made aware of potential benefits of CCU as a parallel and complementary technology to CO2 storage and barriers could be brought down so that the opportunities of CCU would not be lost. Internationally, recommendations include founding an International Energy Agency implementing agreement on CCU, initiate a global technology roadmap for CCU and include it in the Intergovernmental Panel on Climate Change best practices guidelines for national GHG inventories to the UN Framework Convention on Climate Change. The UK's Engineering and Physical Sciences Research Council has identified CCU as an enabling technology in its research vision towards 2050. The fact that the CO2Chem network is functioning is important, as many of the proposed technologies will take years to be realised. By acting now, we can contribute to future chemical feedstocks, as well as make a small contribution to addressing climate change. l *See www.lowcarbonfutures.org/assets/media/clcf_ccu_ report_21_july_final_sm.pdf.pdf Peter Styring is professor of chemical engineering and chemistry and public engagement at the University of Sheffield. Katy Armstrong is CO2Chem network coordinator. Daan Jansen is programme manager carbon capture and storage, Heleen de Coninck is programme manager in the policy studies unit and Hans Reith is project manager/coordinator biorefinery at the Energy Research Centre of the Netherlands Email: firstname.lastname@example.org November 2011 CCU can be profitable with short payback times on investment
December - January 2011