Areola, Raphael I.Adebiyi, Abayomi A.Moloi, Katleho2025-05-202025-05-202025-4-1Areola, R.I.; Adebiyi, A.A. and Moloi, K. 2025. Integrated energy storage systems for enhanced grid efficiency: a comprehensive review of technologies and applications. Energies. 18(7): 1848-1848. doi:10.3390/en180718481996-1073 (Online)https://hdl.handle.net/10321/5949The rapid global shift toward renewable energy necessitates innovative solutions to address the intermittency and variability of solar and wind power. This study presents a comprehensive review and framework for deploying Integrated Energy Storage Systems (IESSs) to enhance grid efficiency and stability. By leveraging a Multi-Criteria Decision Analysis (MCDA) framework, this study synthesizes techno-economic optimization, lifecycle emissions, and policy frameworks to evaluate storage technologies such as lithium-ion batteries, pumped hydro storage, and vanadium flow batteries. The framework prioritizes hybrid storage systems (e.g., battery–supercapacitor configurations), demonstrating 15% higher grid stability in high-renewable penetration scenarios, and validates findings through global case studies, including the Hornsdale Power Reserve (90–95% round-trip efficiency) and Kauai Island Utility Cooperative (15,000+ cycles for flow batteries). Regionally tailored strategies, such as Kenya’s fast-track licensing and Germany’s H2Global auctions, reduce deployment timelines by 30–40%, while equity-focused policies like India’s SAUBHAGYA scheme cut energy poverty by 25%. This study emphasizes circular economy principles, advocating for mandates like the EU’s 70% lithium recovery target to reduce raw material costs by 40%. Despite reliance on static cost projections and evolving regulatory landscapes, the MCDA framework’s dynamic adaptation mechanisms, including sensitivity analysis for carbon taxes (USD 100/ton CO2-eq boosts hydrogen viability by 25%), ensure scalability across diverse grids. This work bridges critical gaps in renewable energy integration, offering actionable insights for policymakers and grid operators to achieve resilient, low-carbon energy systems.37 penAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/02 Physical Sciences09 Engineering33 Built environment and design40 Engineering51 Physical sciencesSustainable energy solutionsGrid managementPumped hydro storageLithium-ion batteriesHybrid storageRenewable energyGrid efficiencyIntegrated energy storage systemsArticle10.3390/en18071848