ECN publication
Assessment of carbon-rejection processes as a method of CO2 abatement: IEA Greenhouse Gas R&D Programme United Kingdom
Published by: Publication date:
ECN 1-6-2000
ECN report number: Document type:
ECN-C--00-035 ECN publication
Number of pages: Full text:
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As an alternative to the capture and storage Of CO2, it has beensuggested that processes which recover energy from the hydrogen content and reject the carbon content of fossil fuels as a solid would be potentially attractive methods of avoiding CO2 emissions. Such processes avoid the need to store CO2 for many years in a save repository. The key reaction involved is thermal decomposition of a fossil fuel. In case of methane decomposition roughly 50% of the energy remains in the rejected carbon and is not recovered. Any version of this process that only makes use of the hydrogen product will therefore have at most a theoretical efficiency of 50%. In practice the efficiency is likely to be significantly less as the reaction is strongly endothermic, 75% of the input mass is rejected as carbon. Some researchers have come to the conclusion that, for such a process to be of interest, the rejected carbon has to be used rather than just stored indefinitely. There are 2 major suggestions involving use of the carbon, which are assessed as part of this study: (1) Use the carbon in established uses for carbon black; and (2) Use the carbon in the metallurgical industry. An alternative application of this technology which will also be assessed in this study has been suggested elsewhere. In the there proposed 'Camol process', the thermal decomposition of methane is integrated with the production of other energy products. Carbon is rejected and the hydrogen produced is reacted with CO2 recovered from power generation to make methanol. The integrated process claimed to result in a net reduction in CO2 emissions compared to conventional processing of oil for transport fuels, together with power generation from fossil fuels. The overall objective of this study is to assess the competitiveness of carbon rejection schemes as means of CO2 abatement. The scope of work for this study is specified in 3 tasks: (1) different types of carbon rejection processes will be assessed to establish their performance and costs. The current and future world market potential for carbon black will be assessed. The world market will be compared to worldwide CO2 emissions from fossil fuels; (2) the potential use of carbon black in the metallurgical industry will be assessed; and (3) the attractiveness of the Camol process as a means of CO2 abatement will be assessed. The reject carbon produced is not used in the Camol process, it is either stored or sold. Methanol is used as transport fuel. Natural gas will be used in the hydrogen generation process and coal in the power generation. An alternate case will illustrate the effects of using natural gas in both the hydrogen production and the power generation step. The results will include derivation of the costs of reducing CO2 emissions. 9 refs.

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