Estonian energy storage company Skeleton Technologies is now valued at more than $1 billion after closing a nine-figure strategic round led by Siemens. The companies did not disclose the exact investment amount or the financial terms of the deal.
The company plans to invest more than $200 million into scaling up operations and R&D in Silicon Valley, where it will work directly with hyperscalers on power systems for AI data centres. The company also wants to start producing cells in the US, so that its American supply chain covers the full route from cells to finished systems.
CEO Taavi Madiberk said the funding would help Skeleton scale up manufacturing in the United States and establish a fully integrated US value chain, from cells to complete systems.
AI is scaling faster than the power infrastructure behind it
Large GPU clusters can cause rapid fluctuations in power demand, placing additional strain on data center electrical systems. Managing these swings is becoming increasingly important as operators scale AI workloads and seek to get more computing performance from their available power capacity.
Skeleton develops high-power systems that absorb these fluctuations. They combine supercapacitors made with the company’s proprietary Curved Graphene material with power electronics and system-level controls. According to Skeleton, the technology can cut energy use by up to 40% and improve GPU performance by double-digit percentages.
“AI is scaling faster than the power infrastructure behind it. The constraint is not how many GPUs you can buy, but how much compute you can extract from every GPU and every megawatt,”
— Madiberk said.
He added that in AI infrastructure, supercapacitors are becoming the new semiconductors.
The International Energy Agency (IEA) expects global data centre electricity consumption to nearly double, from around 485 TWh in 2025 to 950 TWh by 2030, while electricity consumption from AI-focused data centres is projected to triple over the same period.
Beyond data centers, Skeleton supplies its systems for electrical grids, defence and other critical infrastructure.
A strategic partnership with Siemens
The investment builds on a partnership that goes back several years. Siemens supported Skeleton’s expansion in 2023, and Siemens Digital Industries designed and automated the company’s SuperFactory in Leipzig, Germany.
“Skeleton’s portfolio perfectly complements Siemens’ comprehensive data center offering,”
— said Markus Grabmeier, President of Electrical Products at Siemens AG.
Under the agreement, Siemens will integrate Skeleton’s supercapacitor technology into its data center infrastructure portfolio and hold exclusive rights to sell and scale the company’s products in the data center market. The partnership will combine Siemens’ electrical infrastructure offering with Skeleton’s power systems, extending Siemens’ reach from the grid connection to the AI rack.
On the road to a US listing
Skeleton was founded in 2009 in Tartu by Taavi Madiberk and Oliver Ahlberg and is now headquartered in Tallinn. Earlier this year, the company announced a €33 million first close of a pre-IPO round and said it is aiming for a US stock market listing in 2027. The latest investment could help advance those plans.
With the new valuation, Skeleton joins the small group of Estonian-founded companies that have reached unicorn status, a list that includes names such as Bolt, Wise and Pipedrive.
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