Experimental validation of a fuel cell-based tri-generation system with active heat recovery for greenhouse: Heating

In this study, an integrated tri-generation system combining fuel cells and renewable energy was developed to meet the cooling, heating, and power demands of a 660 m 2 greenhouse. An experimental investigation was conducted, focusing on the heating mode during the winter season. The integrated system comprises two natural gas polymer electrolyte membrane fuel cell systems, one hydrogen fuel cell system, a solar thermal collector, two air-source electric heat pumps, a designed heat pump, an adsorption chiller, and multiple thermal storage tanks. Based on the real-world demonstration conducted from January 7 to March 16, 2025, three representative dates were selected depending on the weather conditions and the method of fuel cell waste heat recovery. Thermal and electrical supply and demand were analyzed and compared by component for each case, and performance over the entire experimental period was also evaluated. The results show that the more effectively the fuel cell waste heat was recovered, the less dependent the system became on the electric heat pumps for heat supply, resulting in reduced electrical power demand. In particular, the designed heat pump developed in this study enabled active recovery of fuel cell waste heat, significantly reducing electrical power demand while enhancing thermal storage capacity. This resulted in a coefficient of performance defined in this study 2.8 times higher than when the fuel cell waste heat was negligibly recovered, 1.6 times higher than when it was recovered using a heat exchanger. Over the entire period, the integrated tri-generation system successfully met the daily greenhouse heating requirements.