A novel offshore energy station with poly-generation of power, fresh water, heat, cold and ice

Abstract

Energy storage system with large capacity, high efficiency, low cost and long time is major bottleneck, limiting the large-scale deployments of offshore wind power. To improve energy recovery efficiency and energy storage density, here underwater compressed air energy storage (CAES) with isobaric operation is proposed. At about 5 MPa storage pressure, energy recovery efficiency and energy storage density for traditional CAES are respectively 59.45 % and 2.94 kWh/m3, while they increase to 70.35 % and 6.59 kWh/m3 respectively for underwater CAES. The frictional pressure loss of underwater pipeline for air delivery has a remarkable effect on the performance of underwater CAES, and energy recovery efficiency and energy storage density increase from 51.92 % to 67.97 % and from 4.85 kWh/m3 to 6.28 kWh/m3 respectively when the pipeline diameter increases from 0.35 m to 0.45 m. To improve economic profit and utilize interstage compression heat and high frequency electrical energy more efficiently, an offshore energy station with poly-generation is proposed, which has the energy recovery efficiency of 58.26 % and energy storage density of 7.16 kWh/m3, and generates 358.22 MWh of electrical energy, 252.75 GJ of thermal energy, 66.10 GJ of cold energy, 123.23 tons of ice and 257.25 tons of fresh water each day, opening new ways of deploying offshore wind power and offshore energy storage and also providing strong support for developing and utilizing sea resources and conquering the oceans.