Executive snapshot

United Downs has moved from commissioning to sustained operation, delivering continuous, low‑carbon electricity under contract to Octopus Energy and generating an early domestic lithium stream. The plant is sized to supply roughly 10,000 homes and accessed basement granite at nearly three miles depth, with reservoir temperatures approaching 200°C — sufficient for binary‑cycle generation and for mobilising dissolved lithium in circulated fluids. Cumulative project spend to date is around £50m and the initial lithium campaign is supported by a targeted public grant to defray early extraction costs.

Technical profile and relation to broader EGS developments

United Downs deploys engineered circulation through fractured granite — a co‑production model that pairs power generation with mineral recovery — and represents a demonstration of this combined value stream. By contrast, recent US projects using enhanced geothermal systems (EGS) techniques, notably Fervo Energy’s Utah development, are pursuing rapid upscaling to utility sizes (Fervo’s site targets first generation in 2026 and a nameplate in the tens of megawatts). The divergence highlights two commercialization pathways: relatively compact, mineral‑anchored UK projects that add domestic critical minerals to the revenue stack, and larger US EGS plants focused on bulk dispatchable power.

Market consequences and supply‑chain implications

If United Downs sustains reliable output and lithium yields validate scale‑up, the model could tilt procurement strategies for energy‑intensive buyers — data centres, battery assemblers and hyperscalers — toward bundled offtake deals that combine baseload power with local mineral supply. That is especially salient as other markets race toward utility EGS: large‑scale projects expand the pool of baseload renewable supply, while UK projects potentially shorten battery supply chains by adding domestic lithium. Both dynamics reduce exposure to volatile gas markets and concentrated refining hubs, but their timing, scale and investor appeal differ.

Policy, finance and replication barriers

High upfront drilling costs, reservoir performance uncertainty and induced seismicity management are common constraints across both UK and US efforts. Public support has played a decisive role at United Downs (including a modest grant for lithium work), and US pilots are also leveraging public testbeds and agency support to derisk EGS scale‑up. Replication in the UK will need faster permitting, clearer fiscal incentives for co‑production, and serial drilling to drive down unit costs; in the US, demonstration of long‑term reservoir performance at higher output will be needed to attract utility‑scale capital.

Strategic consequences and sectoral outlook

United Downs is a demonstrator that may shift bargaining power toward integrated developers that pair drilling, mineral processing and long‑term offtakes; Octopus Energy’s contracted position gives it an early retail and corporate sales advantage. Meanwhile, larger EGS projects such as Utah’s could reconfigure capacity planning by adding dispatchable clean power at bulk scale. Collectively, these parallel efforts signal expanding investor interest in geothermal as both baseload renewables and as a potential new domestic source of critical minerals — but they also show that different geographies and business models will shape who wins: miners and mineral processors in co‑production sites, and drilling/platform developers in utility EGS deployments.

Risk remains: economics depend on replicable drilling cost reductions, effective reservoir management (including seismic mitigation), and scalable low‑concentration lithium processing. United Downs’ success is an important step, but it is a single, relatively small project compared with the multi‑tens‑of‑MW ambitions now emerging in the US; both outcomes are needed to materially change global electricity and battery supply chains.