Steam cycle options for the retrofit of coal and gas power plants with postcombustion capture

Abstract

In a period where fast learning-curves for capture technologies can be expected it is important that plants built as carbon capture-ready avoid becoming potential stranded assets during the period of time when the plant operates without capture. At the same time recent evidence shows that decarbonisation of electricity generation cannot be achieved without a CCS option for gas plants. This article first proposes steam turbine design options to build combined cycle gas turbine plants as carbon capture-ready. Then steam cycle options for the existing fleet of coal-fired units are then presented. Although these plants have not been initially designed to operate with CCS it is possible to achieve effective thermodynamic integration–and an overall electricity output penalty in kWh per tonne of CO2 close to a plant built with capture from the outset–with appropriate steam turbine retrofits. Finally, novel insights into the design of capture-ready steam cycles are discussed for futureproofing pulverised coal plants that may have capture fitted after the first learning cycles of postcombustion capture technologies occur or that may be upgraded over their lifetimes.