Development of a hybrid compressed gas engine/PEFC power system using the dissociation expansion characteristics of gas hydrate

The pressure of dissociation and expansion of a gas hydrate can fully power a compression gas engine with a temperature change from 0 °C to 10 °C. The use of green energy (high temperature) and simple refrigeration (low temperature) can easily provide this temperature difference. The dissociation characteristics of a hydrate can be used to develop a clean and efficient hydrate actuator (HA). In this paper, we examine the operation of a hybrid power system consisting of an HA engine and a proton-exchange membrane fuel cell (PEFC), using an example application of an individual house in Sapporo, Japan. A power-generation system that uses the exhaust heat of a PEFC and the cold energy of a heat pump to dissociate and recombine a hydrate is proposed. The results of this analysis indicate that the average electricity production efficiency on a representative day may reach 60.5%. This technique of using the dissociation expansion characteristics of a gas hydrate for power-generation deserves further attention in the search for clean energy.