Performance assessment and economic evaluation of trigeneration energy system driven by the waste heat of coal-fired power plant for electricity, hydrogen and freshwater production

This study considers simultaneous onsite hydrogen, freshwater production as well as electricity using a new trigeneration system powered by the waste heat of a 660 MW capacity conventional coal-fired power plant. Organic Rankine cycle has been integrated into the flue gas path for energy recovery and hence drives both proton exchange membrane electrolyzer and reverse osmosis desalination system. The system has been investigated through a thermodynamic and economic approach considering several variables. The results show that outputs are positively affected mainly because of flue gas temperature improvement. In particular, a trigeneration energy system can produce the highest value of 257.7 kg/h freshwater for domestic usage and 18.9 kg/h hydrogen to feed synchronous generator cooling. In addition to that, overall exergetic performance of the trigeneration energy system is found to be 39.22% and hence entire system performance increases by 0.12% when the conventional steam power plant transforms to the trigeneration. Furthermore, the investment, operation and maintenance costs required for the installation of the trigeneration plant were handled separately and the payback period was calculated as 6.2 years.