Assessing the global viability of solid gravity storage in decentralized hybrid microgrids

Decarbonizing decentralized power networks requires autonomous hybrid renewable microgrids equipped with sustainable bulk energy storage. Tower-based solid gravity energy storage is emerging as a promising alternative to electrochemical batteries, but its techno-economic and environmental viability within off-grid systems has not been comprehensively assessed at a global geospatial scale. This study maps the global boundaries of gravity storage integration by evaluating its specific cost, life-cycle carbon footprint, and optimal sizing dynamics across diverse climatic conditions. The modeled district comprises commercial and residential buildings with typical dimensions, schedules, and specifications, and its electricity demand is dynamically captured through annual hourly simulations based on local weather data and responsive air conditioning, lighting, and equipment load calculations. A high-resolution, multi-objective optimization framework was applied to 6017 worldwide sites, using country- and region-specific cost and emission data, to size autonomous systems comprising solar photovoltaics, wind turbines, backup diesel generators, and solid gravity storage. The algorithm minimized the demand-based levelized cost of energy and life-cycle carbon intensity while enforcing near-perfect grid reliability, and structural robustness was validated through a multidimensional Monte Carlo sensitivity analysis. Gravity storage is universally indispensable for autonomous reliability, with optimal capacities ranging from 7.77 MWh in equatorial zones to nearly 79 MWh in extreme high latitudes. Except for extreme-climate sites, gravity storage offers a highly competitive (either comparable or clearly superior) alternative to conventional battery storage, with drastically lower environmental implications. In favorable climates, the technology achieves a median specific storage cost of ∼0.10 USD/kWh. The optimized microgrids exhibit strong performance globally, yielding an interquartile demand-based cost range of 0.058 to 0.120 USD/kWh. However, extreme northern climates impose severe economic and carbon penalties due to the massive infrastructural oversizing required for extended periods of resource deficits. These findings provide a generalizable guide for siting and sizing gravity-based off-grid networks and advancing the commercial deployment of the technology.