12 - Fossil energy

Abstract

As a higher efficiency replacement to steam-Rankine cycles, indirectly heated sCO2 power cycles warrant in-depth consideration for use in fossil-fueled power plants. In this configuration, the heat of combustion from an external coal or natural gas combustion process is transferred into the supercritical CO2 (sCO2) cycle via a primary heat exchanger, in a similar manner to a boiler in a steam-Rankine power plant. In addition to its typically large-scale, fossil-fueled power plants offer additional challenges to the application of sCO2 power cycles, most notably in the range of temperatures required for making efficient use of the flue gas thermal energy for power generation. Options for sCO2 power cycles and efficiently coupling them to primary heat exchangers are considered in this chapter, including recovery of lower temperature flue gas thermal energy, which is critical for effective thermal resource utilization and minimizing the size and cost of the sCO2 cycle. Performance and cost of fossil-fueled indirect sCO2 cycles from the literature to date are compared, as well as particular sCO2 cycle component challenges that are unique to fossil-fueled power plants.