Writing about emerging geothermal technology requires dealing with the fact that it is emerging in different forms in different places.
A common thread of what’s new are methods based on drilling wells into hot rock to deliver fluid into hot formations to harvest energy.
Chances are that sentence is not exactly an accurate description of any particular method because of the significant differences among them. Some use hydraulic fracturing while others do not. One pumps water from well to well, another into the fractures of a single well, and the third keeps the fluid inside the wellbore.
And the end product varies as well.
In the US, the big early developments are aimed at generating electricity for the grid and storing energy in developments where wells are fractured.
In Germany, the big target is providing hot water to district heating systems that deliver it to a wide range of customers in urban areas. New technology there must avoid fracturing. In Germany, they are testing a new geothermal method that harvests heat in deep well loops using a fluid that brings energy to the surface with minimal pumping.
“In Utah or Nevada, the use case is they do electric only versus in Europe where it is more heat plus electricity,” said Florian Mueller, a PhD candidate doing research on geothermal at the Energy and Technology Policy Group in Zurich, Switzerland.
In both cases these methods were developed by startups whose early commercial applications require adapting to a mind-numbing list of external factors.
As a result, “Geothermal will look different everywhere,” said Ken Medlock, the senior director of the Center for Energy Studies at Rice University, during a panel session at this year’s Offshore Technology Conference (OTC).
Adaptation
The differences reflect a common challenge faced by innovators. A practical solution to a pressing problem, engineered to be reliable and cost‑competitive, is just the starting point. Growth from there will depend on how they adapt to the market.
In the US, Fervo Energy’s first large-scale commercial project in southern Utah is heating water by pumping it from injection wells to production wells through rock fractured from both sides. Produced water will need to be around 400°F—higher is better—to ensure it can be used to efficiently generate electricity for consumers in southern California.
In southern Germany, Calgary-based Eavor Technologies is building a series of 12 flow loops with cased vertical wells linked by a long, uncased lateral that is treated to ensure the fluid remains in the wellbore and is heated efficiently.
When built, each loop will be filled with a fluid formulated to conduct geothermal energy to the surface where it will be used for home heating during the cold months, and electric generation during warmer ones.
The differences often reflect the vagaries of regulation.
Fervo is building its 400 MW geothermal electric plant, Cape Station, 500 miles from its initial customers at a site in southern Utah where the quality of the formation was already known because it adjoins the US geothermal test site commonly known as FORGE.
Also, the remote desert site minimizes the likelihood of opposition to drilling and fracturing, which is not the case in California which has banned fracturing.
On the plus side, Fervo is selling the power to users in southern California because that state is providing critical early support for geothermal. It requires power suppliers in the state to buy electricity from low-carbon producers capable of power on demand, which excludes solar and wind projects that dominate the market there.
Future growth will require finding other customers that need a lot of low-carbon electric power on demand.
Fervo and Sage’s early backers include Google, Meta, and the US military. In both cases “reliability of service is critical,” said, Ajit Menon, vice president, geothermal at Baker Hughes, during the OTC panel discussion.
Selling Heat
While US companies are selling electrons, geothermal producers in Europe are more focused on selling hot water for delivery by district heating systems which now rely heavily on gas for heating.
“Heating is not a big product in the US, but it is big in Europe,” said Stephan Hannke, business development geothermal department at Austrian energy company OMV. During the OTC panel he explained why the integrated oil company wants to shift from importing gas to producing geothermal energy.
It would supply heated water to city utilities in Austria, and other European countries, which are required to create plans to meet government mandates to phase out fossil fuel use by 2050. In Austria, he said this could include tripling the size of the district heating system.
OMV sees geothermal energy as a potential replacement for the natural gas currently used in district heating, which accounts for more than 60% of household heating fuel in Austria, he said.
Making those plans a reality will require public support for projects requiring up-front investments that will take years to pay down.
While the goal of the mandates is to reduce carbon emissions blamed for global warming, Hannke and others see people embracing another motivation for change—energy security.
That has been a worry of European consumers since the price of the gas quadrupled as imports from Russia were curtailed after that country went to war with Ukraine.
“Gas prices were going to crazy levels,” he said. While prices “are back to normal,” consumers want to control their energy supplies.
This is a significant about-face for OMV which was Austria’s biggest gas producer. “We are the ones that did contracts with Russia and brought it over,” to Austria and other European countries, Hannke said.
Efforts to deliver on that promise with geothermal are at the pilot stage.
OMV and Vienna’s city utility, Wien Energie, have partnered on a geothermal heating project on the outskirts of the capital. This commercial scale pilot plant is tapping a natural geothermal formation, which a project announcement said would produce enough hot water to heat 20,000 houses (20 MW) by 2026.
“The energy transition motivation has gone from climate change to energy security, particularly in Europe,” said Neil Ethier, vice president of business development for Eavor.
Evidence of the power of that change is the increase in customer support for local initiatives to drill hot water wells that will replace gas for heating water in district heating systems.
In the past, about one-third of the customers surveyed would opt in to district heating upgrades, said Mueller. “Since the surge in prices due to the war in Ukraine, it is essentially 100% of the customers,” allowing cities to do bigger, more efficient projects.
But drilling geothermal wells is one of many options for replacing Russian gas including: imported liquefied natural gas, solar, wind, heat pumps, and battery storage.
In both the US and Europe, geothermal has long been limited by the fact that formations offering the heat, water, and permeability are hard to find. The fact that district heating can use water that is not much higher than its boiling point increases the options but the drive to drill to produce a lot more geothermal heated water will test those limits.
Scaling up will likely require new geothermal technology, such as Eavor’s project in Geretsried, Germany, which is on the site of a previous failed effort to produce heated water from a traditional geothermal formation.
The Eavor plant, which is scheduled to go into operation in 2026, is expected to produce nearly 65 MW of thermal energy and more than 8 MW of electricity over its 30-year life, the firm said.
While the method does not require fracturing, oil industry skills and hardware are still needed to identify, plan, drill, and complete geothermal projects. A paper by Mueller reported on how the limited onshore oilfield services in Germany has slowed development.
Production from geothermal wells in Germany has gotten hotter over time as heavier duty drilling rigs have become available to drill deeper.
The top temperature of water produced from previous wells in Germany is 320°F at nearly 20,000 ft (160°C, 6000 m), according to the paper.
This is well short of the temperatures reached by Fervo in Utah, which have exceeded 400°F.
Levels that high are required for relatively efficient electric production, but water for home heating doesn’t need to be nearly that hot.
Another Possibility
While district heating is not common in the US, it is used in some large developments such as office complexes or medical centers.
There’s another use of geothermal water heating that has been little used on both sides of the Atlantic—using geothermal to heat water for industrial processing.
“Industrial heat is perfectly achievable in many cases,” including food processing and plastics making, Mueller said, adding, “There is a lot of low hanging fruit.”
But even in Europe, it is a new idea. He said Daimler and Volkswagen are drilling wells to provide industrial heat for truckmaking operations.
In the US, it’s hard to find similar examples.
“It is little on the back burner,” in the US said Koenraad Beckers, a research engineer at the National Renewable Energy Laboratory.
The big barrier to entry for geothermal in US factories is that natural gas is relatively cheap, and there is a large installed base of gas-powered heating equipment.
While a geothermal well or two could eliminate the need for a plastics maker to buy gas, that option looks less attractive to a plant manager faced with paying a rate that allows a geothermal company to build the system.
This could change over time as geothermal gets cheaper and regulations putting a price on carbon emissions become more common and costlier. But that is a lot of ifs in the US where the rich tax credits offered for options like building carbon storage, are not available.
This is an example of a common challenge for those selling new technology, which prompted Mueller to say: “The question is always what does it compete with?”
For Further Reading
Learning in Geothermal Power and Heat Generation—A German Case Studyby F. Mueller and T. Schmidt, Energy and Technology Policy Group; and B. Steffen, Climate Finance and Policy Group.
