Google and Meta are accelerating investment in long-duration energy storage (LDES) to secure reliable, lower-carbon electricity for expanding AI data centers. At least 150 gigawatt-hours of LDES projects have been announced, approved or financed in the United States since the beginning of 2025, more than five times the nation’s planned capacity at the end of 2024. The projects span iron-air, CO2, zinc-based, gravity, flow-battery and compressed-air technologies and target durations from 10 hours to more than 100 hours, compared with roughly four hours for conventional lithium-ion batteries. Google’s projects include a 300 MW / 30 GWh Form Energy iron-air system in Minnesota, a 19 MW, 10-hour Energy Dome system in Arizona and a separate 23 MW / 200 MWh Energy Dome project planned for Ireland. Meta has reserved up to 1 GW / 100 GWh from Noon Energy, beginning with a 25 MW / 2.5 GWh pilot targeted for 2028. Commercial performance and costs remain unproven at scale, with most projects expected to come online from 2026 to 2030.