Assess the current state of grid-scale energy storage technologies, identify the cost and capacity gap preventing full renewable grid integration, and evaluate the technological and policy pathways to closing it.

Techno-economic analysis of 12 grid storage technologies (lithium-ion, flow batteries, compressed air, hydrogen, gravity storage, thermal). Cost trajectory modeling using learning curves. Grid integration modeling for 100% renewable scenarios across 15 national grids.

Solar and wind are now the cheapest electricity sources in history — but their variability requires storage to replace dispatchable fossil fuels. Current grid-scale storage (predominantly lithium-ion) can provide 4-8 hours of dispatch — inadequate for the multi-day and seasonal storage needed for a fully renewable grid.

Long-duration storage (100+ hours) costs $200-500/kWh — 5-10x too expensive for widespread deployment at current prices. The 2030 global storage requirement for a Paris-aligned grid is 680 GWh — current deployments are at 45 GWh. Lithium-ion costs fell 97% since 1991; similar learning curves are projected for iron-air and vanadium flow batteries by 2030-2035.

The gap is real but closeable — if R&D investment reaches $20B/year vs current $4B/year.