Retrofitting CO₂ capture to existing power plants as a fast track mitigation strategy

Carbon capture and storage (CCS) is often identified as an important technology for mitigating global carbon dioxide (CO₂) emissions. For example, the IEA currently suggests that 160GW of CCS may need to be installed globally by 2030 as part of action to limit greenhouse gas concentrations to 550ppm-CO₂eq, with a further 190GW CCS capacity required if a 450ppm-CO₂eq target is to be achieved. Since global rollout of proven CCS technologies is not expected to commence until 2020 at the earliest this represents a very challenging build rate. In these circumstances retrofitting CO₂ capture to existing plants, probably particularly post-combustion capture on pulverized coal-fired plants, could play an important role in the deployment of CCS as a global strategy for implementing CO₂ emissions reductions. Retrofitting obviously reduces the construction activity required for CCS deployment, since fewer additional new power plants are required. Retrofitting CCS to an existing fleet is also an effective way to significantly reduce CO₂ emissions from this sector of the electricity generation mix; it is obviously not possible to effect an absolute reduction in coal power sector CO₂ emissions simply by adding new plants with CCS to the existing fleet. Although it has been proposed that plants constructed now and in the future can be 'capture ready', much of the existing fleet will not have been designed to be suitable for retrofit of CO₂ capture. Some particular challenges that may be faced by utilities and investors considering a retrofit project are discussed. Since it is expected that post-combustion capture retrofits to pulverized coal plants will be the most widely applied option for retrofit to the existing fleet (probably regardless of whether base plants were designed to be capture ready or not), a review of the technical and potential economic performance of this option is presented. Power cycle performance penalties when capture is retrofitted need to be addressed, but satisfactory options appear to exist. It also seems likely that the economic performance of post-combustion capture retrofit could be competitive when compared to other options requiring more significant capital expenditure. Further work is, however, required both to develop a generally accepted methodology for assessing retrofit economics (including consideration of the implications of lost output after retrofit under different electricity selling price assumptions) and to apply general technical principles to case studies where site-specific constraints are considered in detail. The overall conclusion from the screening-level analysis reported in this paper is that, depending on project-specific and market-specific conditions, retrofit could be an attractive option, especially for fast track initial demonstration and deployment of CCS. Any unnecessary regulatory or funding barriers to retrofit of existing plants and to their effective operation with CCS should, therefore, be avoided.