Novel massive thermal energy storage system for liquefied natural gas cold energy recovery

Abstract

The concept of heat integration with cryogenic energy storage (CES) is a possible option for the recovery of wasted cold energy from liquefied natural gas (LNG). For maximizing energy storage capacity, we propose a conceptual design for a massive cryogenic energy storage system integrated with the LNG regasification process (MCES). The novel aspect of this study is the transmission of LNG cold energy via two different methods at different times: (1) MCES stores cold energy in liquid propane during on-peak times, enabling increase in the energy storage capacity; and (2) MCES directly transfers cold energy with help of liquid propane during off-peak times to liquefy air using surplus electricity from the grid. Thus, the surplus energy is stored in liquefied air and released to generate electricity on demand. Based on the process simulation, exergy analysis and economic evaluations are conducted. MCES exhibits a round trip efficiency of 85.1%, whereas existing bulk power management systems exhibit a maximum efficiency of 75%. Moreover, using a three-million-ton-per-annum LNG regasification plant, MCES enables the supply of 138 MW of electrical power which is up to 96% more power than that achieved by other recently proposed process designs, and has potential for bulk power management.