Harnessing Hell's heat - The UK has switched on its first deep geothermal power plant at United Downs in Cornwall, marking the country’s first use of super-heated underground water to generate electricity. Developed by Geothermal Engineering Ltd (GEL) over nearly two decades at a cost of £50 mln, the project involved drilling three miles below the surface - the deepest onshore well in the UK - to access water heated to nearly 200C by granite rock. This heat is used to drive turbines, producing continuous, “always-on” renewable electricity sufficient for up to 10,000 homes. The power has been contracted to Octopus Energy for delivery via the national grid. Deep geothermal differs from shallow geothermal systems such as heat pumps because it reaches much higher temperatures capable of generating electricity, not just heating. While geothermal energy offers stable, 24/7 output without fuel price volatility, the British Geological Survey and industry representatives noted that high upfront drilling costs present a major barrier to wider deployment. The project received funding from private investors and £15 mln from the European Development Fund. In addition to electricity, the plant will produce lithium carbonate from underground fluids - the UK’s first domestic commercial lithium supply - initially around 100 tonnes per year, with plans to scale up significantly. The UK has further geothermal potential in regions such as Scotland and northeast England, though no additional deep geothermal electricity projects are yet approved. Industry stakeholders say stronger government policy support is needed to attract investment. While shallow geothermal systems are expanding more rapidly due to lower costs, global investment in deep geothermal electricity is rising quickly, driven partly by growing electricity demand from data centres and clean energy needs. (BBC)