Potential for flexible operation of pulverised coal power plants with CO2capture

Abstract

Fossil-fired plants play an important role in electricity networks as mid-merit plants that can respond relatively quickly to changes in supply and demand. As a consequence, they are required to operate over a wide output range and play an important role in maintaining the quality and security of electricity supply by providing response and reserve capacity. Carbon dioxide capture and storage (CCS) has been identified as a critical technology for future electricity generation from coal in the UK. Although the performance of CCS schemes where CO2 capture plants are operated at full load has been considered in detail, part load performance is less well understood. Developing a better understanding of part load performance of plants operating with CO2 capture is crucial in determining their suitability to operate as mid-merit plants. This paper presents an assessment of the potential impact of adding post-combustion CO2 capture at pulverised-coal power plants. Estimated performance of steam cycles working with post-combustion CO2 capture plant are presented at full and part load, leading to performance predictions for pulverised-coal power plants operated over a range of loads and with varying levels of CO2 capture. By adjusting the operation of the capture plant, as well as the boiler/steam cycle, an extended range of operation can be achieved including lower minimum stable generation levels and additional 'pumped storage like' capacity for times of high demand. For example, plant operators can alter the energy penalty for the CO2 capture plant with an associated change in plant output by reducing the level of CO2 capture. This can allow extra electricity to be generated and sold when electricity prices are high. With solvent storage it should also be possible to increase power plant output for a number of hours, but without associated increases in CO2 emissions.