Siemens Turns Skeleton Technologies Into a Unicorn

Siemens has taken a leading role in a new funding round for Skeleton Technologies, the Estonian energy storage company focused on the power problems behind A.I. data centers. The round lifts Skeleton’s valuation above $1 billion, which puts it in unicorn territory. Skeleton did not reveal the size of the investment, but chief executive Taavi Madiberk called it a “9-digit investment round,” so the check is at least $100 million.

The deal is bigger than money. Siemens now has exclusive worldwide rights to sell and scale Skeleton’s products in the data center market, and Skeleton’s supercapacitors will be folded into Siemens’s electrical infrastructure offering. That stack runs from grid connection all the way to the A.I. rack. Siemens says nine of the world’s 10 largest data center operators already use its systems.

This isn’t a cold start. Siemens has been a technology partner since 2022 and an investor since 2023, and Siemens Digital Industries helped design and automate Skeleton’s SuperFactory in Markranstädt, near Leipzig. The transactions still need the usual closing conditions, so nothing is fully done yet.

Skeleton’s pitch is simple: A.I. clusters create brutal power swings in milliseconds. Thousands of GPUs can jump from idle to full load together, creating load spikes in the megawatt range that put pressure on equipment and the grid. Skeleton’s Curved Graphene-based supercapacitors sit close to the hardware and absorb those spikes. The company says that can cut energy use by up to 40 percent and improve GPU performance by double digits.

The company is also leaning hard into the U.S. market. More than $200 million of the new money is slated for production scale-up and research and development in Silicon Valley, plus its own U.S. cell manufacturing. Skeleton already makes supercapacitors in Saxony and runs a SuperBattery factory in Finland, but it has not said where or when U.S. cell production will begin. It also gave no new detail on its planned U.S. IPO in 2027.

The timing fits a bigger problem. Skeleton cites International Energy Agency figures showing global data center electricity use rising from about 485 terawatt-hours last year to 950 terawatt-hours in 2030. In the U.S., data centers are expected to drive about half of the growth in electricity demand, which is already nudging plans for new gas power plants.