The well funneled steam for months at temperatures of over 450°C – a world record. Geothermals rarely reach higher than 60-80°C. The magma-heated steam generates 36MW of electrical power, considerably more than the 1-3MW of an average wind turbine.

Can enormous heat deep in the earth be harnessed to provide energy for us on the surface? A promising report from a geothermal borehole project that accidentally struck magma – the same fiery, molten rock that spews from volcanoes – suggests it could.

2021-07-06: The prospects for geothermal

If we want not just to replace current energy consumption with low-CO2 sources, but also to, say, increase global energy output by 10x, we need to look beyond wind and solar. Nuclear fission would be an excellent option if it were not so mired in regulatory obstacles. Fusion could do it, but it still needs a lot of work. Next-generation geothermal could have the right mix of policy support, technology readiness, and resource size to make a big contribution to abundant clean energy in the near future. Combining the planet’s reserves of uranium, seawater uranium, lithium, thorium, and fossil fuels yields 365K zetajoules. There is 41x as much crustal thermal energy than energy in all those sources combined. (Total heat content of the planet, including the mantle and the core, is ~1000x higher.)

What if we had much better drilling technology? Put aside the fancy stuff, like horizontal segments—what if we could simply drill straight down into the earth much deeper and faster and cheaper than we can today? This one capability would unlock a huge increase in geothermal power density. With depth comes higher temperatures. If we could cheaply and reliably access temperatures around 500ºC, we could make water go supercritical. This would unleash a step-change in enthalpy, without the closed loops otherwise needed for supercritical fluids. By doing EGS (concept #1) in these hotter conditions, we could get the biggest benefit of EGS—a high surface area to use to transfer heat—with one of the biggest benefits of closed-loop systems—the use of a supercritical working fluid. In addition to higher enthalpy, supercritical steam will produce higher electrical output in virtue of a higher delta-T in the generator cycle. Output of the cycle is directly proportional to the temperature differential between the steam and ambient conditions.

2022-02-08: New ways of drilling

If you want to reduce the cost of drilling really deep holes, you need a drilling system that doesn’t break as it comes in contact with granite, can handle high temperatures and pressures, and that doesn’t require tripping. Is there a way to use pure energy to obliterate the granite? That is what Quaise Energy is working on. The company is developing a drilling system that uses gyrotron-generated mm-wave directed energy to vaporize granite.

If Quaise succeeds, high-efficiency geothermal energy becomes available everywhere on the planet. No matter where you are on Earth, if you go deep enough, it is hot. By targeting 500ºC heat at depth, Quaise will be able to produce supercritical steam at the wellhead. If we could produce supercritical steam from the ground, we could convert our dirty coal plants into 0-CO2 electricity sources by simply piping the steam from the ground into the turbines.

2022-07-30: More detailed look at the economics

There is a 5% chance geothermal delivers more than 10% of our electricity. And that estimate won’t change until more improvement comes.

More than one technology needs commercialization to achieve <$20/MWh. The heat engine problem is critical to solve and should drive further engineering decisions. The numbers won’t work in many places building new steam power plants. Repowering coal plants or better thermoelectric generators provide the most flexibility in solving the other challenges. A supercritical CO2 power cycle likely requires almost perfect execution elsewhere. Improvement in drilling costs is also non-negotiable. If techniques to increase heat transfer via fracturing don’t work, methods to use directional tools in high-temperature, high-pressure environments become a requirement.

Geothermal has incredible potential but has a tortuous path to market given the stiff competition from other electricity generation sources and mismatches in markets, technology, and regulation. Improving drilling technology to reach depths that can create supercritical steam for existing coal plants is likely the fastest and highest probability path to a 10% market share.

2023-02-12: A modest proposal

Through a new copper-based engineering approach on an unprecedented scale, this paper proposes a safe means to draw up the mighty energy reserve of the Yellowstone Supervolcano from within the Earth, to superheat steam for spinning turbines at sufficient speed and on a sufficient scale, in order to power the entire USA. The proposed, single, multi-redundant facility utilizes the star topology in a grid array pattern to accomplish this. Over time, bleed-off of sufficient energy could potentially forestall this supervolcano from ever erupting again. 11 Quadrillion Watt hours of electrical energy generated over the course of 1 year, to meet the current and future needs of the USA is shown to be practical.

2023-03-23: Repurposing fossil fuel tech

There’s already signs that spillovers are happening. The US government has developed a fluid to fracture impermeable rocks to open up more geothermal reservoirs, a process identical to the one that frackers use in petroleum deposits. Start-up Eavor Technologies Inc. plans to use the horizontal drilling pioneered by the unconventional oil and gas industry to build radiator-like networks of pipes in areas that would otherwise be unsuitable for development.
Shell Plc set up a geothermal division in 2018 that’s been exploring the potential of the technology to provide heat for buildings and industry in the Netherlands. Baker Hughes Co., the former oilfield services division of General Electric Co., has developed deep, high-temperature drilling technologies to tap reservoirs that can produce heat more efficiently than conventional ones.
There’s even proposals to use the technologies to produce other materials crucial to the energy transition. Current geothermal wells operating near California’s Salton Sea might be able to extract enough lithium from underground brines to meet US demand 10x over. One of the world’s few operating green hydrogen facilities is powered by a geothermal plant just outside Iceland’s capital Reykjavik.

2023-04-25: More on that Yellowstone proposal

Trying to build an enormous geothermal power plant and associated transmission lines(!) in one of the most beloved National Parks(!!), which there’s specifically a law against (!!!), and which could potentially trigger a civilization-destroying volcanic eruption (!!!!) is like the final boss of the permitting reform movement.

2023-07-03: There’s been a lot of drilling progress

The geothermal technology flywheel is getting close to being self-sustaining. Commercial closed-loop projects should be operational within the next 2-3 years. They will spark copycats if they are successful. Companies pursuing other technologies can switch immediately by changing vendors and their well design, similar to how many solar thermal projects converted to photovoltaics.

Talent isn’t an issue in North America or Europe because the oil industry constantly trains and sheds workers due to the market cycle. Geothermal companies can hoover up the laid-off and disillusioned. It could be an issue in the areas of the world with thin oilfield service markets.

Process heat should be more profitable than electricity, but companies love touting electricity because of the large addressable market. Electricity is trendy! There should be demand for repeatable, low-risk architectures in either application, but electricity will require subsidies or favorable market rules in most locations for now. I’d recommend caution to any lobbyists trying to alter electricity markets to favor zero carbon, dispatchable power plants with >90% percent capacity factors and onsite fuel. Other technologies might find geothermal power plants producing $50/MWh electricity with sub 2-year construction times hard to beat!

Having the chance to get in the game and hone your craft is all you can ask for. Geothermal looks like it will get that chance. That could drop the cost of delivering process heat precipitously while the power plant portion of capital expenditure would quickly dominate electricity production cost. Developers and service companies will incrementally improve depth and temperature to increase the addressable market. Competition looms from other carbon-free process heat technologies and renewables firming techniques. Only time will tell if geothermal can gain a foothold in providing heat or earn a double-digit share of the electricity market.

2023-11-21: Learning rates are looking promising

Heat-only closed-loop geothermal using conventional drilling technology has the fastest scaling potential of any geothermal variant. It takes much longer to iterate on fracture design, build/interconnect power plants, or develop new drilling technology. There is no shortage of market opportunity with heat. Something like half of Europe’s energy use is heat, and most is theoretically addressable by geothermal. China’s district heating systems use as much energy as the United Kingdom.

The smaller service footprint also eases the scaling of labor and equipment. Producing 3000 drilling rigs instead of 1000 rigs is simpler than ramping production of every drilling and completion service item. Geothermal companies with heat purchase agreements can sign long-term rig contracts that allow manufacturers to borrow money for working capital and faster scaling. Fast growth isn’t guaranteed, but the supply chain shouldn’t be the limiter.