Flexible CCS plants–A key to near-zero emission electricity systems

Abstract

Abstract Power generation processes with CCS that are capable of operating at variable load will be needed to achieve deep reductions in emissions of CO 2 to the atmosphere. This paper assesses the effects of operating load factor on costs of coal and gas fired power generation processes with CCS and analyses the emissions and costs of fossil fuel fired plants in an electricity system that includes 35% wind and 25% nuclear generation. The paper shows how the costs of generation increase at an increasing rate as the emissions are reduced using power plants with integrated CCS such as post combustion capture, because many of the CCS plants have to operate at low load factors. This could be avoided by using coal gasification plants with CCS which feed hydrogen to underground buffer storage and then to flexible combined and open cycle gas turbines. The gasification, CO 2 capture and storage equipment would operate at base load which would avoid potential practical difficulties of flexible operation and reduce costs. Emissions from the fossil fuel plants in the system with wind and nuclear generation could be reduced to 16 g/kWh at electricity costs competitive with coal-based post combustion capture with emissions of 140 g/kWh. Emissions from the overall electricity system including the wind and nuclear would be 6 g/kWh.