Hybrid photovoltaic-liquid air energy storage system for deep decarbonization

Nowadays most photovoltaic (PV) plants usually use battery energy storage technology to smooth fluctuant power, but batteries have the drawbacks of a short lifetime and environmental pollution. The existing renewable power networks have serious problems with decarbonizing electricity on the end-user side. This paper investigates a new hybrid photovoltaic-liquid air energy storage (PV-LAES) system to provide solutions for the low-carbon transition for future power and energy networks. In this article, a local PV power plant cooperates with its maximum power point tracking (MPPT)-based boost converter, to generate low-carbon electricity with some uncertain fluctuations. Then a zero-emission-air-based LAES unit is used to absorb the surplus power from the PV plant, and also compensate power for the local load with inadequate power level. This makes the new system save a large proportion of power from main grids, which can also indirectly reduce greenhouse gas emissions. For the MW-class PV-LAES case, results show that the surplus renewable electricity (6.73 MWh) generates 27.12 tons of liquid air for energy backups during the day time, and then the LAES unit has a round-trip efficiency of 47.4% that can discharge a flexible power compensation to the load in the night. Accordingly, the grid power demand reduces significantly from 12.78 to 3.33 MWh in a day. In this way, the annual power savings is estimated to be 3449.25 MWh, and the corresponding carbon emission can be reduced by 2607.63 tons. Regarding the economic performance, the PV-LAES system presents a dynamic payback period of 9.33 years and an accumulated life-cycle net profit of $2,260,011. Overall, the proposed PV-LAES scheme is economically feasible from a life-cycle perspective, and can potentially realize flexible energy interaction with local renewables to achieve an integrated low-carbon power generation and storage system.