Solar energy storage systems: A comprehensive study for techno-economic aspects and sustainable grid integration
Mostafa Esmaeili Shayan
Abstract
This study utilizes a systematic literature review methodology to investigate different solar energy storage systems (SESS), including electrochemical, thermal, mechanical, hydrogen systems, and liquid air energy storage (LAES), in order to address the challenges associated with intermittency and to guarantee efficient and sustainable grid integration. The key performance indicators studied include round-trip efficiency, energy density, cycle life, and levelized cost of storage (LCOS). Economic limitations are highlighted, encompassing significant initial investment and dependence on subsidies. Electrochemical technologies, for instance lithium-ion batteries, attain high round-trip efficiencies (90–97 %) and energy densities (250–350 Wh/kg), making them suitable for short-term applications. However, they exhibit significant carbon footprints (60–100 kg CO 2 /kWh) and LCOS (0.15–0.30 USD/kWh), requiring recycling rates of 90–95 % for sustainability. Nevertheless, mechanical and thermal systems, including pumped hydro storage (PHS) and molten salt storage, provide a low LCOS ranging from 0.05 to 0.10 USD/kWh for PHS, alongside minimal emissions of 1–10 kg CO 2 /kWh. These systems are well-suited for large-scale, long-term storage, boasting cycle lives that exceed 40,000 cycles, despite geographical limitations. Emerging technologies such as LAES and hydrogen storage exhibit moderate efficiencies (60–70 % for LAES, 40–60 % for hydrogen) and substantial storage capacities (up to 1000 MWh for hydrogen), with projected reductions in LCOS of 60 % by 2040 through AI-optimized hybrids, effectively addressing intermittency in both remote and grid-scale applications.