The pressures of integrating renewable energy sources and powering the exponential increase in high-demand data centers are testing the limits of traditional power systems. While short-duration lithium-ion batteries have been instrumental in managing daily energy fluctuations, other technologies may become a part of the solution.
For true grid resilience, especially during extended periods of low wind or sun, a new class of technology is emerging: multiday storage (MDS). These systems are designed to deliver power for days, not hours, providing the reliability that utilities and data center operators need to confidently navigate current power demands.
Various forms of MDS have been piloted and tested for years, but now we’re starting to see actual deployments. Recent announcements of specific projects or commercialization have been made by three pioneering startups: Form Energy, Ore Energy and Noon Energy.
Beyond Lithium-Ion: A New Class of Battery
There are two primary technologies leading the charge for 100-hour batteries:
Iron-air batteries: Developed by companies like Form Energy and Ore Energy, these batteries operate on the principle of “reverse rusting.” They take in oxygen to rust iron, generating electricity. During charging, an electrical current removes the rust, preparing the system for its next use.
Solid oxide fuel cell (SOFC) systems: Developed by Noon Energy, this technology stores energy in a carbon-based medium and uses a high-temperature fuel cell to convert it back to electricity when needed.
Both types of batteries are packaged together like traditional battery energy storage systems (BESS), in that the cells are arranged into modules that are housed inside shipping containers, and multiple shipping containers are installed together to increase capacity.
These technologies are designed not to replace lithium-ion batteries but to complement them. While their round-trip efficiency is lower, their dramatically lower cost and ability to provide sustained power for multiple days make them an intriguing asset for running the grid on renewable energy over the long term.
Preparing for Prime Time
MDS has been talked about and explored for years without widescale adoption. However, major technology companies are making significant investments in long-duration storage to secure the massive, stable power required for their AI infrastructure:
Google is partnering with Form Energy to install a 300-megawatt/30 gigawatt-hour iron-air battery system for its data center in Minnesota.
Meta recently signed an agreement with Noon Energy to reserve up to 100 gigawatt-hours of capacity to support its own AI buildout, with the first project scheduled for 2028.
Hyperscalers are proactively securing multiday energy storage to de-risk their future operations and have access to reliable, clean power needed to train and run next-generation AI models. These systems provide long-term energy reliability that bridges the gap when renewable sources are unavailable for extended periods because of weather or other factors.
What to Watch
New market dynamics are coming into focus in the modern energy landscape. Several questions bear ongoing attention:
Outside of hyperscalers, will the marketplace pay for MDS technology?
Will independent system operators (ISOs) be interested, or even potentially require it in the future?
Given how different the technologies are from current widely adopted energy storage options, what will it take to operate and maintain MDS?
While long-term performance and cost per kilowatt-hour data for these new systems will become clearer over time, the current actions of large-scale energy users represent a notable trend toward speed and resource certainty. This shift underscores the value of staying informed on how these emerging technologies can support future energy strategies.