Cycling of coal fired power plants: A generic CO2 emissions factor model for predicting CO2 emissions

A constant CO2 emissions factor in energy mix models is often used when trying to show the CO2 emissions reduction benefit in deploying a large amount of renewable power on the grid. This approach is flawed due to its inability to capture the impact of cycling operations on the emissions characteristics of various coal fired power plants (CFPPs). This can be improved by incorporating a model that predicts the turbine cycle heat rate of different types of CFPPs at various load conditions. Such a generic variable turbine cycle heat rate (V-TCHR) model has been developed in a previous study. This paper discusses the application of the V-TCHR model for determining the CO2 emissions factor of CFPPs at varying load conditions. A demonstration study was carried out to investigate the CO2 emission characteristics at part load of six hypothetical CFPPs having different re-heat architectures. The predicted emissions factors were compared against published benchmark data and found to agree very well. The variable emissions factor model presented is useful to energy modellers as it does not require detail thermodynamic plant models, or gross assumptions, and can be used to model any hypothetical CFPP-based energy system.