Coal power flexibility, energy efficiency and pollutant emissions implications in China: A plant-level analysis based on case units

Integration of intermittent renewable energy in the power systems requires balancing service of conventional fossil fuel power plants, which is mainly provided by coal power in China. However, flexible operation of coal power units will incur energy efficiency penalty, and output additional CO2 and pollutant emissions. In this paper, we use a high-resolution operation dataset collected from two typical coal power units to evaluate environmental impacts of flexible operation of coal power in China. To address this, we examine the generation mechanisms of CO2 and three atmospheric pollutants by coal power units, and then calculate the emissions. We also outline the potential of coal power units to perform flexible operation and discuss retrofit options for more efficient flexible operation. In addition, we use plant-level operation data from typical-sized coal power units to estimate emission levels during processes of start-up, deep cycling and regular operations. In the case 300 MW and 600 MW unit respectively, deep cycling operation would incur an increase of 17.5% and 11.3% in heat rate and CO2 emissions factor, 10.2% and 108.4% in NOx factor, and 41% in dust factor, compared with full load operation. The NOx emissions of a cold start-up in the case 300 MW and 600 MW unit are roughly the amount of 8 hours and 12.3 hours of regular full load operation, respectively. This paper has implication on employing flexible operation of coal power to integrate renewable energy in China's coal-dominated power systems.