Long-Duration Battery Startups Raise $1.3B as Data Centers Seek 24/7 Clean Power

The $1.3 Billion Bet on Multi-Day Energy Storage

Form Energy has raised $750 million in a round led by T. Rowe Price, bringing its total funding to roughly $2 billion. The company is using the capital to expand production of iron-air batteries that can store electricity for multiple days from its plant in Weirton, West Virginia. Rival Antora Energy has secured $550 million to accelerate its own long-duration storage technology: thermal batteries built around industrial carbon blocks that hold heat for at least 100 hours.

Together, the two startups have attracted about $1.3 billion in fresh funding. The immediate driver is data center demand. Large computing facilities need reliable, clean power around the clock, and cheap solar and wind generation alone cannot supply constant electricity because those sources are intermittent. Long-duration storage is being positioned as the link between low-cost renewable supply and the 24/7 load profile of data centers and industrial plants.

Form says it now has orders to build more than 80 gigawatts of battery capacity, enough by its estimate to serve 60 million homes. Named customers include Xcel Energy and Crusoe for data center projects in Minnesota and Texas, plus a grid project in Ireland with Future Energy Ireland. Antora’s first large system is a five-gigawatt-hour installation at Poet’s biofuel plant near Big Stone City, South Dakota, where heat from the battery is used to produce steam for converting corn into ethanol.

Both companies say their designs use cheap, domestically available materials and carry minimal or no fire risk compared with lithium-ion batteries. Form, led by former Tesla battery executive Mateo Jaramillo, says an IPO could come as soon as next year. PitchBook estimates Form’s latest valuation at about $4.3 billion; the company has not confirmed that figure.

Why Form’s Iron-Air and Antora’s Carbon Blocks Are Winning Grid Orders

Where Data Centers Fit in the Storage Boom

Data centers are not simply another customer category for these batteries; they are the main near-term demand signal. A solar farm produces cheap power during the day but cannot follow a data center’s constant load through the night or through cloudy periods. Form’s projects with Xcel Energy and Crusoe in Minnesota and Texas, and its Ireland grid work with Future Energy Ireland, show that multi-day storage is being procured to firm up renewable supply for computing infrastructure rather than only for traditional utility peak shaving.

Form Energy’s Iron-Air Economics and Order Book

Form’s iron-air battery uses a reversible oxidation process: a porous iron plate oxidizes when electricity is supplied, and the rust is converted back to iron when the battery charges again. Because iron is not consumed, the system is designed for decades of cycling. The company is targeting a cost of $20 per kilowatt or less, which it argues would make solar-plus-storage cheaper than natural gas. A stated order book of more than 80 gigawatts is substantial, but it is still a pipeline rather than installed capacity, and the company has not publicly demonstrated the $20 per kilowatt target at scale.

Antora’s Carbon-Block Simplicity and Industrial Steam Market

Antora stores energy as heat in solid carbon blocks heated to 2,400 degrees Celsius inside containers filled with inert gas. The heat is then released over days to make steam for data centers or industrial processes. The company says its 9,300-square-meter San Jose plant can already produce tens of gigawatt-hours of storage capacity, and it is looking for a second assembly plant. Its five-gigawatt-hour project at Poet’s ethanol plant is the clearest test of whether carbon-block storage can replace fossil-fuel steam at a cost that beats alternatives. Antora has not disclosed system pricing because it is in commercial negotiations.

What the Two Rounds Say About the Long-Duration Storage Market

Investors such as T. Rowe Price and G2 Ventures are betting that multi-day storage built from low-cost materials can capture a market that short-duration lithium-ion batteries cannot serve well. The logic is that solar is the cheapest form of energy in history, but its intermittency requires storage that lasts days, not hours. The main uncertainty is whether these companies can convert their order backlogs and cost targets into delivered systems quickly enough to meet data center timelines and beat natural gas on price.

What the Funding and Order Backlogs Mean for Energy Buyers

For energy buyers and investors tracking these companies, the funding rounds point to several concrete near-term checkpoints:

• Watch Form Energy’s Weirton production ramp and its $20 per kilowatt cost target. If the company reaches that level alongside cheap solar, it argues the combination can beat natural gas on cost, which would strengthen its case to data center and utility buyers.
• Track the Xcel Energy and Crusoe data center projects in Minnesota and Texas, plus the Ireland grid project with Future Energy Ireland. These deployments will show whether iron-air storage performs at the scale implied by Form’s 80 gigawatt order book.
• Follow Antora’s Poet project in South Dakota. The five-gigawatt-hour system is the clearest public test of whether carbon-block thermal storage can deliver industrial steam and power at a lower cost than alternatives.
• Prepare for possible public market exposure to Form Energy next year. Jaramillo has indicated an IPO could occur, but the company remains private and has not confirmed timing or valuation.

For industrial steam users and data center developers, both technologies offer a non-lithium option with minimal fire risk. Buyers in active procurement should ask vendors for round-trip efficiency, degradation data, and delivered cost per megawatt-hour over multi-day discharge, since those metrics will determine whether the systems can replace gas peakers or existing short-duration batteries.