AI data center expansion is accelerating investment in long-duration energy storage (LDES), which stores electricity for far longer than conventional lithium-ion batteries. Since the beginning of 2025, at least 150 gigawatt-hours of LDES projects have been announced, approved, or financed in the United States—more than five times the nation’s total planned capacity at the end of 2024. The surge is being driven largely by data center demand for reliable, lower-carbon power. Google is partnering with Energy Dome on a 19-megawatt, 10-hour CO2 battery system in Arizona, while Meta has reserved up to 1 gigawatt and 100 gigawatt-hours from Noon Energy, with the first phase expected by 2028. Crusoe is working with Energy Vault on gravity storage. Orders from AI data centers are also helping startups secure financing, validate their technologies and expand manufacturing. The sector remains unsettled, spanning CO2, gravity, flow battery and compressed-air systems, with commercial performance and costs still unproven at scale. As projects come online between 2026 and 2028, LDES could help convert intermittent wind and solar generation into dispatchable power for data centers and eventually other markets.