Integrating hydrogen storage and thermal batteries for cost-effective green energy solutions

Systems running significant percentages of green energy clearly show the mismatch between power demand and availability over seasonal variations. Conventional and thermal and electrical energy storage systems cannot handle this problem. This work investigates large-scale hydrogen storage using salt caverns by combining thermal energy storage technologies with batteries to improve solar wind power system flexibility over time. Minimizing power consumption, lowering energy supply losses, and computing the levelized cost of energy (LCOE), among several optimization goals, help to identify the best system configuration and capacity characteristics. The system's performance is assessed with and without related equipment and hydrogen storage. Under highly reliable power supply, results show that integration of cheap hydrogen storage in salt caverns considerably lowers the total installed power requirement for energy generation and storage systems. It lowers the LCOE to $0.244 per kilogram, a $0.216 per kWh difference from a system with hydrogen storage tanks when the annual energy needs are fully met. This offers a significant financial benefit. Furthermore, lowering the LCOE by $0.55 per kWh compared to systems without hydrogen storage emphasizes the possibilities of salt cavern hydrogen storage in particular power supply situations. Tri-objective optimization also results in a 76% reduction in annual power constraints. Still, more general use depends on future cuts in the unit investment cost for fuel cells and electrolyzers. • Salt cavern hydrogen storage significantly improves system economics: It reduces LCOE to $0.244/kg and achieves up to $0.55/kWh cost reduction compared to systems without hydrogen storage. • Lower infrastructure requirements: Integrating hydrogen storage reduces total installed generation and storage capacity, making the system more efficient and cost-effective. • Enhanced renewable flexibility and reliability: Combining hydrogen storage with batteries and thermal storage helps balance seasonal mismatches between energy supply and demand in solar–wind systems. • Optimization yields major performance gains: Tri-objective optimization leads to a 76% reduction in annual power constraints, improving system stability under high reliability conditions. • Future cost dependency remains: Wider adoption depends on reducing capital costs of electrolyzers and fuel cells, which are currently limiting scalability.