System analysis and appraisal of SOFC-primed micro cogeneration for residential application in subtropical region

Based on the promising development of solid oxide fuel cells (SOFC), they are proposed as prime mover in a micro cogeneration system for residential use in subtropical climate. In application with significant cooling demand, it is a challenge to apply conventional trigeneration design due to the inherently low energy performance of the heat-driven cooling equipment. In addition, if the price difference between electricity and gas is not too distinct, economic feasibility would become a hurdle to implement trigeneration. However, the approach of SOFC-primed micro cogeneration can be considered, and the power generated was used for both air conditioning and electrical appliances, whereas the waste heat was recovered for water heating. Eventually, building cooling, heating and power demands could be fulfilled, particularly in the hot-humid season. In order to maximize its energy and environmental merits, an optimal design and control for the thermal energy storage were worked out. It is found that the SOFC-primed micro cogeneration system could have reduction of 26.0% and 30.8% in annual primary energy consumption and CO₂ emission respectively against the conventional system. Meanwhile, the payback period based on net present value is 10.7 years.