Analysis of the performance of an electricity generation system using the CO2 hydrate formation and dissociation process for heat recover

Abstract

In Japan, approximately 70% of the primary energy supply is converted into low-temperature (lower than 200 °C) waste heat, which represents a small energy density; therefore, its utilization is limited to applications such as heat pumps, organic Rankine cycle, etc. In this paper, therefore, work from the heat source with a small difference in temperature is obtained using a gas hydrate power cycle. Furthermore, a new electric generator system is proposed. In the gas hydrate power cycle, gas hydrate is produced due to a low-temperature heat source (environment of a cold area), and then dissociated, resulting in high-pressure gas, due to a high-temperature heat source. In this cycle, the temperatures of the heat sources were set at −5 °C and 15 °C; therefore, in the proposed system, cold environment and waste heat can be considered as the low and high temperature heat source, respectively. With this system, the dissociation efficiency of CO2 hydrate when using a generation catalyst was at 42.5%, and the instant power conversion percentage of the actuator and generator was at 40.2%. Finally, 17.1% of the heat provided by the high-temperature heat source was converted into electric power by CO2 hydrate power cycle.