SteamyTea

Environment How to unlock unlimited geothermal energy, anywhere we want Earth contains more than enough heat to power humanity many times over, but so far only a few lucky places have been able to exploit it. Now we may have a way to tap this vast clean energy source almost anywhere By Katharine Sanderson 21 July 2026 A geothermal power station in Iceland’s Hengill region, one of the few countries with natural geothermal reservoirs that allows it to turn underground heat into power Science Photo Library Deep under your feet, Earth is hot. Really hot. Some of that heat is left over from the planet’s violent formation. More is continually created by the splitting of radioactive atoms in the rocks below. In a few places, Earth’s hidden furnace dramatically makes itself known, bursting through the crust as volcanoes, geysers and rivers of magma. Spectacular stuff, but also extremely useful – if we can get at it. Conventional geothermal power works best wherever geology has done the hard work for us: where fault lines crack the crust and hot water or steam rises close to the surface. That’s why countries like Iceland, New Zealand, Kenya and Indonesia can turn Earth’s heat into warmth for homes and electricity for grids, while much of the rest of the world has barely touched it. Its appeal is obvious. Unlike solar power, geothermal doesn’t fade when the sun sets, and unlike wind power, it doesn’t stall when the air is still. Over the past decade, advances in drilling have begun to loosen geothermal power from its geological shackles. Some projects aim to improve on nature, creating cracks and pathways where none existed. Others are more ambitious still: they want to drill so deep that geothermal power could work almost anywhere. “Ultimately, the whole world is the goal,” says Matt Houde, co-founder of geothermal energy company Quaise Energy. That would turn it from a niche resource into something far bigger – a way to tap the planet’s hidden heat wherever we happen to need it. How we harness Earth’s heat To convert heat from Earth’s interior into usable energy, engineers pump cold water into naturally occurring reservoirs in hot rock. There, it warms up and returns to the surface as hot water or steam, which can be used to drive turbines and generate electricity. The water is then sent back underground to begin the cycle again. It’s a simple concept, and unlike fossil fuels, geothermal heat sources are practically inexhaustible on human timescales. “If you measure in terms of the energy stored within the Earth’s crust, geothermal heat exceeds by orders of magnitude all hydrocarbons,” says Houde. The trouble is that traditional geothermal requires three ingredients to work: heat, water and rock that is permeable or fractured enough for water to move through it. “Traditional geothermal systems are very constrained to countries and regions within countries where you have this unique combination of conditions,” he says. That is why geothermal has flourished in places like Iceland. Sitting astride the mid-Atlantic ridge, the country has those core ingredients in unusual abundance. The global oil crisis in the 1970s pushed Iceland to exploit that advantage, and geothermal now makes up over a quarter of the country’s electricity supply. That may not sound like much, but Iceland’s geothermal plants can keep generating whatever the weather, making them a steady backbone for the grid. “Geothermal is really well placed to be the glue that will make low-carbon electricity systems work,” says Iain Staffell, a sustainable energy expert at Imperial College London. However, most countries don’t share Iceland’s good fortune. They may have heat or water or fractured rock, but not all three at depths that are easy to reach. Traditional geothermal plants are limited to mining heat from less than 2 kilometres underground. Go much deeper, and the engineering becomes brutal. Drills must chew through hard, hot rock. The vertical shafts that connect the surface to heat reservoirs, known as wells, must survive punishing temperatures and pressures. Even after all that, the rock may still be too tight and unbroken for water to flow through it. A worker surveys the vast interior of a geothermal cooling tower in Monterotondo Marittimo, Italy Alessia Pierdomenico/Bloomberg via Getty Images Still, the prize is enormous. The International Energy Agency estimates that geothermal’s technical potential is around 150 times current global electricity demand, assuming we can exploit heat down to about 8 kilometres. Conventional geothermal typically taps pre-existing reservoirs of hot water or steam in permeable, fractured rock less than 2 kilometres underground, leaving much of that potential out of reach. The implication is clear: to expand the resource, engineers must drill deeper – and create the underground plumbing that nature hasn’t provided. Enhanced geothermal The first of the new geothermal techniques does exactly that. Enhanced geothermal systems target hot but impermeable rock, typically 2 to 10 kilometres underground. Engineers pump in hot water at high pressures to open or widen fractures and create pathways for fluid to circulate. This is known as an enhanced geothermal system (EGS), and it is the most mature technology in geothermal’s new era. But this approach has a downside. Forcing water into deep rock doesn’t just create useful cracks. According to a 2023 review of the research, it can also disturb older, pre-existing faults that are already under strain. Many faults are held still by friction, like a heavy book resting on a tilted table. Pump water into them, and the pressure in their pores and fractures rises. That partly props the two sides of the fault apart, reducing the force clamping them together. If the fault was already close to slipping, that can be enough to induce an earthquake. An investigation commissioned by the South Korean government concluded that a nearby EGS project triggered a magnitude-5.5 earthquake in the city of Pohang in 2017. More than 80 people were injured and the earthquake caused an estimated 300 billion Korean won (£148 million) of damage, making it the most destructive in the country’s history. Is a broken jet stream causing extreme weather that lasts longer? Scientists are scrambling to understand how climate change may be interfering with the winds that carry our weather, with potentially catastrophic consequences Bill Ellsworth at Stanford University in California was part of the team that helped establish what role the geothermal plant played in the disaster. “In Pohang, they drilled a couple of wells that were a long way apart,” he says. The hope was that pumping water into one would fracture the rock enough to connect with the other, creating a route for water to pass between them and gather heat. But trying to force that kind of connection through the subsurface is risky, particularly if the drilling intersects faults that are already primed to slip. That is why newer projects are trying to be more deliberate, says Ellsworth. In Iceland, for instance, engineers try to create EGS reservoirs more gently without blasting them open all at once by pumping cold water slowly and at relatively low pressure. Over months, the cooling rock contracts and cracks, says Lilja Magnúsdóttir, executive vice president of resources at Icelandic energy company HS Orka. Iceland also has an advantage born of necessity: it is a seismically restless place, so the country has already invested heavily in monitoring. At HS Orka, that now includes using geothermal wells themselves as early-warning sensors. When magma begins to move, it compresses the surrounding rock, creating a telltale signal in the well. “It’s a really cool design,” says Magnúsdóttir. But even where EGS projects have learned to manage seismic risk, hard rock still makes an unreliable basis for a plumbing system. Fluid can leak away and contaminate groundwater, for instance. And the same fractures that make the system useful can also make it dangerous. Advanced geothermal One way around this is to stop asking the rock to carry water at all. Where natural fractures and reservoirs don’t exist, an alternative to EGS is to drill a sealed loop through hot rock. Engineers drill down, then sideways, until the boreholes connect underground, before lining and sealing them with steel and cement. That creates something like a buried radiator where fluid circulates, but never comes into direct contact with the rock itself. This closed-loop system is known as an advanced geothermal system (AGS), and it has been tested successfully in Germany, where Canadian energy company Eavor has developed a geothermal power plant at Geretsried, which began construction in 2022 and started producing electricity last year. Because closed-loop systems don’t force fractures open in the rock, they should reduce the risk of induced earthquakes. And because they don’t depend on continually pumping water into and out of those fractures, they should reduce it further still. In a few places, including south-western Iceland, Earth’s buried heat lies close enough to the surface to be tapped easily by geothermal plants. Water from this plant also supplies the nearby Blue Lagoon geothermal spa Dieter Telemans/Panos Pictures There is another possible advantage. If the working fluid stays inside a sealed pipe, it doesn’t have to be water. Companies can, in principle, use fluids that pick up and release heat more efficiently. Eavor’s working fluid is a company secret. The firm China Huaneng Group, meanwhile, has built the first geothermal demonstration plant that uses supercritical carbon dioxide – CO2 that is compressed and heated until it becomes not quite a gas and not quite a liquid. In that state, it is dense and flows easily, and is very good at moving heat. The firm’s test facility began operating in May this year in Zhengzhou, China. But these systems have their own difficulties. Eavor has had to scale back the number of wells it planned to drill after rock debris clogged parts of the pipe network. Its plant works, but not yet as efficiently as hoped. That points to a broader question: can closed-loop systems circulate enough fluid, and draw heat from the rock fast enough, to be commercially useful? “The jury is still out,” says Ellsworth. “Time will tell whether these ideas of having just a single closed loop will be actually successful.” And while AGS could be safer and cleaner than inducing fractures deep underground, it is still limited to places where hot rock lies within reach, usually a few kilometres down. To make geothermal truly global, companies will have to drill much, much deeper. Supercritical geothermal The deeper you go, the hotter Earth gets. Go deep enough and water crosses a strange threshold. At about 374°C (705°F), under sufficient pressure, it transforms into a supercritical fluid – akin to the CO2 in the China Huaneng demonstration plant – and can carry far more heat than ordinary hot water or steam. “There are a few countries where geothermal does provide a sizable mix of the energy supply. But strictly the heat itself, which is fundamentally what geothermal energy is, is actually available anywhere if you go deep enough,” says Houde. Supercritical temperatures are usually found at depths of at least 5 to 20 km, and often deeper. The rocks become harder the further you go: basalt or granite rather than the softer sedimentary layers often found closer to the surface. This rock chews through even the hardest tungsten carbide or diamond drill bits. Then there’s the time spent not drilling at all but instead replacing worn-down drill bits or equipment that begins to fail at higher temperatures and greater depths. These delays quickly push up costs, says Houde. Quaise Energy uses millimetre waves, a portion of the electromagnetic spectrum, to laser through hard rock found at great depths Quaise Energy Quaise, which is based in Houston, Texas, wants to get around this by drilling in a different way – without using a drill bit at all. Its plan is to use conventional drilling for the upper part of the well, then switch to high-powered microwave energy once the rock becomes too hard. The hole would be lined with corrugated steel, helping the microwaves travel downwards. When that energy hit the rock, it would heat it until the rock cracked, broke apart or even vaporised. “There’s no drill bit mechanically destroying the rock here, it’s just the interaction of the energy with the rock,” says Houde. The rock would be reduced into a fine ash that is purged from the well with a nitrogen-rich gas and collected at the surface. Quaise isn’t alone in pursuing non-contact drilling: Slovakia-based GA Drilling is also trialling laser- and plasma-based systems, and carried out its first field tests in 2023. Once the hole is open, Quaise wants to create a deep, EGS-style reservoir. Water would be sent through fractures in superhot rock, picking up heat before returning to the surface to generate electricity. In principle, it is geothermal freed from geography. Rachael Tremlett/New Scientist Quaise’s test holes are still just a couple of kilometres deep, but the company sees them as a proof of concept for something much larger. Its first planned superhot geothermal plant, located in Oregon, is intended to come online by 2030, accessing temperatures up to 400°C (752°F) at a depth of 3 to 5 km. A potential future site would push deeper, potentially to 10 km. “By 2035, we want the first superhot well producing energy at a depth greater than 10 kilometres,” says Houde, who thinks his company’s technology could transform any region into geothermal country. But there are still serious uncertainties. One is whether such deep wells can be kept open under the immense pressures found kilometres below ground. “It’s unclear whether that is possible,” warns Ellsworth. Houde accepts that the hardest engineering lies ahead. “I think it’s very viable for getting to these initial depths to prove superhot geothermal,” he says. “I think it’ll become increasingly more challenging to push the frontier on how deep we can go.” Iceland offers a glimpse of how these different strands of geothermal might converge. Instead of simply resting on its laurels as one of the world’s great geothermal success stories, the country is fast becoming a test bed for what comes next, says Magnúsdóttir. Its deepest geothermal well – the second well by the Iceland Deep Drilling Project, a consortium of the country’s leading energy companies and its energy authority – has already brushed against the promise of superhot geothermal. It was completed in 2017 and goes down 4.7 kilometres. “It is the first well in the world where supercritical conditions were confirmed in the geothermal well,” says Magnúsdóttir. Icelandic operators are also using EGS techniques to get more from existing fields, stimulating deeper faults to reach another kilometre or so of heat. Next year, the Iceland Deep Drilling Project plans to drill its third well. “There, they just have to go down to a little over 2 kilometres to reach supercritical conditions,” says Magnúsdóttir. But even at that relatively shallow depth, the engineering challenges remain fierce. The main problem is well integrity. At such high temperatures, the steel casings that line the well can expand, deform and fail. In Iceland, engineers have been testing fixes, including flexible connectors between sections of casing. This sort of engineering will be crucial if geothermal is to win over investors. Projects are expensive up front and slow to prove, and often need permits before developers know whether a site will work commercially. But the reward for patience can be unusually durable. “It’s very, very costly,” says Sanjeev Kumar at the European Geothermal Energy Council. “But once you’ve drilled that hole in the ground, that lasts for over 100 years.” That is the promise and the problem in miniature. “We know that very deep geothermal energy would be fabulous if we could reach it,” says Ellsworth. “We just don’t yet know if it’s possible.”

If there really is a problem, can it be mitigated by extra insulation in other places?

I seem to remember someone saying that you have stricter waste water rules in Scotland. Not an area I have looked into much.

I shall follow this, not because I want one, just that I find it interesting. You say you don't that a 'reed bed' but is a small orchard not the same thing? 'Let my plops fertilise your crops'

Bit on the radio about Caroline Lucas While I agree with many of the policies that the Green Party have, I don't agree with how they present them, and most are probably, scientifically, dubious. But she did talk about weapon using Net Zero by the politically right. That was interesting. https://www.bbc.co.uk/sounds/play/m002z5y0

A bit of no interest to anyone. BBC article

The government has extended the grant system to cover A2AHPs for both heating and cooling. Trouble is they have not sorted it out yet (just yesterday was on the news about it). So it may be worth hanging on a while and seeing what happens. I think the grant is £2500. As for the price to install, this is always difficult. While technically not difficult (just wire and pipes) any company has to cover a lot of costs, one being warrantee claims. In retail, which this is, it is not unusual to multiply the price several fold. I like the 'large holes though the wall' types for ease of installing, was seriously considering getting one, but they are relatively noisy, around 60 dBs, fine for a living room, but a bedroom maybe not.

You are just a (expletive deleted)ing troll and this is really not the place for you.

I have just been chatting to a mate's partner. They where banging on about Overseas Aid and we need to stop it. If we stopped OA then our Navy would have been ready to send boats to the Gulf. I asked them how much our Military Budget was, they had no idea, asked what the OA budget was, again they had no idea. Then they blamed the Boat People, then the Muslims, then the two tier policing, ended up blaming the local council for not sorting out a pothole in their road. I kept saying that they are reading the wrong newspapers and they need to look up some numbers, rather than spout an opinion. The response to that was 'listen to me, listen to me' When it got to the government not allowing for more drilling in the North Sea, I had to say 'you don't keep up with the news do you.' These (expletive deleted) are allowed to vote, and it is not going to be for Bin Face. So rather than spout opinion about a subject, get some data, then come back and state your case. If you don't, you are just spouting opinions, and as this thread has shown, the opinion spouters refuse to find any data, in fact it is worse than that, they expect others to find it, then say the data is wrong. That is the policy of time wasters and internet trolls.

That was your question. Then you change the question. And changed it again. If you stuck to the original question, you may get helpful answers, it is then up to you to verify the data source, people on here are not your secretaries. I think what you want to know, and this is pure speculation on my behalf, is 'when will my individual electricity bill be lower, in nominal terms, that it has ever been?' That I cannot help you with as it is a nonsense question.

It may show that electricity is not that expensive in reality. But you have to do your own research, you will not believe it otherwise.

Well they are going to allow more drilling and extraction, so should be next Tuesday. We will see unquestionably next tuesday if it happens.

When Susie was a striper, s stripper Susie was She said "Oh Ah, I lost my bra, I left my knickers in the car"

Go to the ONS and get they data sets for household wages and electricity prices. Plot them and see what they show. It is easy enough to do.

My magic trick I do at parties is similar. But rather that a hat and produce a rabbit or dove. I put my hand down my shorts and produce to hares.

How much does it cost to get a chainsaw blade resharpened? Use that as a benchmark.

It is even worse when you lie to yourself, and then believe it.

Does that include the shielding ?

Good idea. Can get the National Trust to do it, they own most of the best carparks down here. Most are just fields, not gird connection, and charge £6 a visit. Take my local carpark in PZ, be nice to cover it over as it does rain a lot here. Now, the interesting bit. We often get 100 MPH winds, with gusts over 120 MPH, so would need a complete redesign. Deep files driven, a very sturdy roof, and maybe a half MW capacity. We could take the build costs totally out of the car park charges. So rather than £1.20 for 3 hours, let them charge £8/hour. Seems cheap to me. When will people realise that the easiest solution is the best. Well I have know idea of your age, but your understanding of complex issues, and your total denial of evidence, suggests you are. So you have summed yourself up nicely.

Some things do not scale well. The lead shielding will be the same thickness, so a (expletive deleted) off big crane will be needed. Why do people think that local generation (at the few MW scale) is better when close to consumption ?

You have a serious problem with people, bordering on paranoia.

It is worth pointing out that we started the transition to low carbon generation nearly 2 decades ago. Apart from some very small scale wind farms, hobby PV and a bit of hydro, we had virtually nothing. Since the we have added 55 GWp if wind and solar. Now the name plate capacity if RE cannot be compared directly with thermal generation, but it contributed close to 40% of our generation. It also contributed to our pumped storage as well. I have not looked at storage capacity in a while, but must be close to 1 GWh now. I cannot see any reason why we should not hit 90% low carbon generation by 2040, except if there is not the political will to do so. I think the political will is there, we tend to hear the naysayers more because they are the vocal minority, the majority says nothing. I am going to repeat what I said about cost. Wind and PV are the cheapest forms of, and it is coming in bold , NEW generation. It is not competing with the same contracts as legacy generation.

Cooling is a lot easier a mile deep under the artic ice caps.

Well according to some it is treated the same by 'the believers'

Yes please.