Energy Storage Technologies and Applications: A Comprehensive Review

The increasing integration of renewable energy sources, particularly solar and wind, has created a growing need for efficient and reliable energy storage technologies (ESTs) because of their intermittent nature. This review critically examines established and emerging ESTs, including batteries, supercapacitors, and mechanical, thermal, hydrogen, and superconducting magnetic energy storage systems, with emphasis on their technical performance, durability, response time, economic feasibility, and environmental considerations. The reviewed technologies exhibit substantial differences in their energy and power characteristics. Lithium-ion batteries, for example, provide an energy density of approximately 100–265 Wh/kg, with reported lifetimes of 2000–10,000 cycles, whereas supercapacitors offer only 5–10 Wh/kg but can withstand more than 100,000 cycles and deliver energy within seconds. Flywheel systems can achieve power densities of 1000–10,000 W/kg and operate for up to 100,000 cycles, while pumped hydro storage has a comparatively low energy density of approximately 0.5–1.5 Wh/kg but can provide service over periods exceeding 50 years. Thermal storage technologies also show considerable potential, with reported energy densities ranging from approximately 0.25 Wh/kg for sensible heat storage to 120–383 Wh/kg for thermochemical storage, depending on the materials and system configuration. Overall, the findings demonstrate that no single storage technology is optimal for all applications. Technology selection should, therefore, consider the required energy and power capacity, response time, lifetime, cost, and environmental impact, particularly when integrating variable renewable energy into modern energy systems.