Fireworks, the AI inference company valued at $17.5 billion in July, has contracted the whole of Era4’s Chesterfield facility in Derbyshire under a multi-year agreement. The site is 5 MW of direct liquid-cooled capacity running Nvidia Blackwell Ultra HGX B300 GPUs, according to Era4’s press release of 28 October. Data Center Dynamics reported the deal on 3 November.
Era4 said in June that it generates around 50MW of power across its estate. By our arithmetic, the 5 MW site Fireworks took is about 10% of that figure.
Business Pill · Sovereign AI Explained
A short explainer on sovereign AI: who controls the model and the data. It teaches the general idea only and does not discuss Fireworks or Era4.
The key insight: Era4’s release says Fireworks has contracted the whole Chesterfield site, 5 MW of B300 capacity, under a multi-year agreement. Era4 said in June that it generates around 50MW across its estate; by our arithmetic, the site is about 10% of that figure.
The release says Fireworks is live on the B300 GPUs in Chesterfield. It does not give a GPU count, a contract value or the length of the term beyond “multi-year”.
The companies will “initially explore joint solutions for financial services, insurance and life sciences”. The planned services are UK-hosted inference with on-demand and dedicated access to open models, fine-tuning and serving models on enterprise data, and joint customer deployments in the UK and Europe.
“This agreement with Era4 expands our capacity in the UK for developing new services with for banks, fintechs, UK enterprises, and other regulated businesses,” said Lin Qiao, co-founder and chief executive of Fireworks.
Tom Humphreys, Era4’s chief executive, said: “For a bank or insurer, knowing where its AI runs is part of the buying decision.”
Megawatts: Era4’s Chesterfield site contracted to Fireworks (5 MW, Era4 release, 28 October 2026), the power Era4 says it generates across its estate (around 50MW) and its hybrid power pathway (over 500MW), both from its 9 June 2026 release with Civo, and The Mill’s planned 1 GW at peak build-out (era4.com). The 10% share is our arithmetic; the 50MW is generation, not data-centre load.
How the Site Is Powered
Chesterfield uses HPE ProLiant Compute XD685 servers in an HPE AI Mod POD modular data centre. Most of its electricity comes from landfill gas captured and burned on site, with a grid connection as backup, the release says.
Era4 says generating its own power let it deploy at Chesterfield quickly, “bypassing grid constraints”. It lists a portfolio of more than 40 sites across the UK with similar potential for energy generation.
In a June release with Cosine, Era4 said Chesterfield “will be going live in Q2 of this year”. The October release gives no date for when Fireworks went live.
Where Fireworks Stands
Fireworks announced a $1.505 billion Series D on 15 July at a $17.5 billion valuation, led by Atreides Management, Index Ventures and TCV, with Nvidia among the other investors. It said it had passed $1 billion in annualized revenue run rate.
The company serves more than 40 trillion tokens a day, with over 95% of that volume coming from models specialised on customers’ own data, the Era4 release says. Its footprint already includes deployment regions in Germany and Iceland, and it is expanding its UK office.
Era4’s Other Plans
Era4 signed a sovereign AI stack partnership with Civo in June and a memorandum of understanding with Cosine on its Lumen Sovereign model. Its largest plan is The Mill, a former steel mill in Newport with a planned gigawatt of power and a 2027 phase-one live date, according to its website.
Newport sits in the South Wales AI Growth Zone that the government announced on 20 November 2025, stretching along the M4 corridor from Newport to Bridgend. At the time the government said “work is now underway to secure an investor to help deliver the South Wales Growth Zone site”. The government release does not name Era4.
The same government release said American inference platform Groq would open its first UK data centre in London. The business lever in the Fireworks deal is capacity: an inference platform renting a whole site so it can sell UK-hosted models to regulated buyers.
As we read the release, the scarce input Era4 is selling is power it makes itself: landfill gas burned on site lets it skip the grid queue, and it says it has more than 40 sites with similar potential.
As we read it, Fireworks is buying location as much as compute: the release pitches UK-hosted inference and fine-tuning to banks, insurers and life sciences firms that want to know where their AI runs.
As we read the two sets of figures, the deal is small next to Era4’s plans: 5 MW against the gigawatt it lists for The Mill in Newport at peak build-out.
Tom Humphreys, Era4 chief executive, Era4 release, 28 October 2026
“Europe has the talent, the data and the demand to lead in enterprise AI, but it cannot lead on compute it does not control”
Three Implications
FOR UK BANKS AND INSURERS The release proposes UK-hosted inference and fine-tuning for uses such as underwriting, financial-crime checks and claims handling, with the services still to be explored.
FOR NEOCLOUDS An inference platform valued at $17.5 billion in July has contracted an entire 5 MW site, according to the release.
FOR UK COMPUTE POLICY Chesterfield runs mostly on on-site landfill gas with the grid as backup, which Era4 says let it bypass grid constraints.
The framework puts it this way: “The structural bottleneck isn’t computing, it’s electrons.”
As we read it, Era4’s pitch to Fireworks is built on that line: Chesterfield generates most of its own electricity from landfill gas, and the release credits that for deploying quickly. The framework does not discuss Era4 or Fireworks.
What Is Not Established
Neither company has disclosed the contract value, the number of GPUs or the exact term. The joint services are described as plans to explore, not signed customer deals.
Era4’s 50MW is power it generates across its estate, not data-centre capacity, so the 10% share compares a contracted site with generation. We cannot tell from the releases whether Chesterfield’s 5 MW is counted inside that 50MW.
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Fireworks has contracted all 5 MW of Era4’s landfill-gas-powered Chesterfield site for Nvidia B300 GPUs under a multi-year deal, to sell UK-hosted open models to banks, insurers and life sciences firms. By our arithmetic, the site is about 10% of the roughly 50MW of power Era4 says it generates.
A note on sourcing. This piece is based on Era4’s press releases of 28 October, 9 June and 8 June 2026 and its website pages, Fireworks’ Series D post of 15 July 2026, and the UK government’s AI Growth Zone announcements. Data Center Dynamics’ report of 3 November could not be read in full. The 10% share is our arithmetic. We did not contact Fireworks or Era4.
Gennaro Cuofano is a CRO and tech executive who has worked in AI since late 2015, starting with bringing NLP, natural-language generation, voice and chatbot products to the marketing industry. His background is in law and finance: he holds a Master's degree in Law and an International MBA with an emphasis on corporate finance (LUISS Business School and the University of San Diego, 2012), and worked as a financial analyst at a real-estate investment firm in San Diego and as an assistant controller. His work focuses on business model strategy, business engineering and, more broadly, structural analysis: how companies make money, read from their own filings. He created FourWeekMBA and leads research there and at The Business Engineer, his newsletter on AI and business strategy, with over 95,000 subscribers and more than 1,000 published analyses. His writing has also appeared on Entrepreneur (for example, How to Digitize a Family Business in Europe) and HackerNoon. Find him on LinkedIn and Substack. See how we source.
