Empirical Evaluation of Compressed Air Energy Storage Integration with Solar PV Systems for Industrial Load Levelling in Abia State

Compressed air energy storage offers a mechanically robust and long-cycle-life alternative to electrochemical battery storage for integrating intermittent solar photovoltaic generation with industrial load requirements in Abia State, South East Nigeria, where industrial electricity demand patterns are characterized by distinct peak periods. This study presents an empirical evaluation of a small-scale compressed air energy storage system integrated with a 15 kWp rooftop solar PV array at a manufacturing facility in Aba. The CAES system employs a reciprocating air compressor, a high-pressure storage vessel, and an air expansion turbine driving a generator, designed to store excess solar generation as compressed air and release it during production peak demand periods or solar generation gaps. Thermodynamic modelling of the CAES system is validated against experimental performance measurements at four operating pressure levels between 6 and 15 bar, yielding a round-trip energy efficiency of 48.3 percent at the optimal operating pressure. A rule-based energy management controller coordinating the solar PV, CAES, and facility load is developed and evaluated over 30 operating days using real solar generation and facility demand data. The CAES system reduced peak grid demand by an average of 34 percent and increased solar self-consumption from 41 percent without storage to 68 percent with CAES integration. Comparison with a lithium-ion battery storage alternative of equivalent energy capacity shows the CAES system achieves lower 20-year levelised storage cost at 0.42 USD per kWh stored versus 0.61 USD for lithium-ion, reflecting the longer cycle life and lower maintenance costs of the mechanical storage system. Keywords: compressed air energy storage, solar PV, load levelling, industrial energy, Abia State