About 12% of all US greenhouse emissions come from heating and cooling buildings, according to Vox. Much of the energy used to heat large buildings — factories, office buildings, universities, schools, and so forth — could come from geothermal sources. The Earth’s core is made up of molten iron, geologists say, though no one has actually been down there to verify that claim. The deeper one goes beneath the surface of the Earth, the hotter things get — as much as 370º Celsius in some cases. The US Department of Energy has put together a dandy graphic showing precisely how that heat could be tapped to serve a variety of purposes.
The average temperature of the Earth from about 10 feet down below the surface to 1000 feet below is around 54º F. That makes ground source heat pumps (GSHP) for residential and small commercial buildings appealing because the pipes don’t need to be buried deeply in order to cool during the summer or heat during the winter. But if we go down deeper, average temperatures begin to rise to the point where the heat of the Earth is already warm enough to heat buildings without heat pumps. In general, underground water that is heated to between 200º and 300º Fahrenheit is ideal for so-called Deep Direct Use (DDU) geothermal systems, which can make district heating for entire cities and towns possible.
Such systems are used in many European cities, especially Reykjavik. Paris is exploring district heating and Munich is as well. The larger the system, the lower the unit costs are. Munich intends to offer geothermal heat as another municipal service, with pipes installed alongside sewer and water lines. New buildings will be able to connect to the DDU system as easily as to other city services.
In the US, Boise, Idaho has used geothermal heating since 1890. Princeton University is shifting from a natural gas steam system to geothermal. The Oregon Institute of Technology, Carleton College in Minnesota, and Ball State University in Indiana already heat with geothermal district heat.
A Hole Is A Hole
When it comes to drilling holes in the ground, the oil and gas industry wrote the book. “The low hanging fruit [for geothermal heat] is our sedimentary basins, between two and three kilometers depth and they have been mapped extensively because of our oil and gas runs. We know their temperatures extremely well — and we found more water than oil in those reservoirs, by the way,” Marit Brommer, tells Vox. She is the head of the International Geothermal Association but began her career as an oil and gas engineer,
“We have a lot better tools now [than in previous decades] — better drilling technology, much better geophysical logging capability, better seismic reflection imaging,” says Jeff Tester, a professor of sustainable energy systems and principal scientist for Cornell University’s Earth Source Heat project. “We know so much more about how to find permeability and fluids in the rock.” Drilling at that depth, avoiding pollution or seismic disruption, is something oil the and gas has been working on for decades.
The Cost Factor
So why isn’t everybody doing it? Upfront costs are a big part of the reason. Just as electric cars cost less to own over time, they cost more to buy initially, which puts a lot of people off. But municipalities have the ability to attract long term investment. The system Munich is considering might cost $100 million or more but can pay for itself in 10 years or less. Having a city-wide DDU insulates the city from fluctuations in fuel costs and provided local jobs — something city leaders are always concerned about. District heating is also quite durable. The oldest system in the world is in Chaudes-Aguies, France and has been in continuous operation since the 14th century.
Municipalities can use policy initiatives like tax incentives, low interest loans, and streamlined permitting to drive down the cost of systems. They can also guarantee loans in order to encourage nervous lenders to take a chance on new technology. “Iceland addressed this risk in the 1960s with the establishment of a National Energy Fund, which offers loans to pay the initial cost of drilling and exploration,” says Jeff Tester. “If the initial drilling stage is unsuccessful, the loan defaults to the state; if the drilling is successful, the loan will be paid as planned.” It is the single most powerful policy tool for expanding geothermal in Iceland, he says.
Costs will come down with scale and knowledge-sharing. “What we need is multiple companies who work in multiple countries in similar sub-service settings, that understand the drilling requirements and the service needs, meaning that the lessons learned in country one can be applied to reduce costs in countries two, three, and four,”says Marit Brommer says. Of course, that assumes that country one is not at war with countries two, three, and four. Collaboration is difficult if the various parties involved are shooting at each other or hurling invective at those on the other side of a border.
A large investment of time, money, and policy attention in geothermal heat could help create jobs in almost every US zip code according to the Department of Energy’s 2019 GeoVision study. It found that “technology improvements could enable more than 17,500 geothermal district heating installations nationwide and 28 million US households could realize cost effective heating and cooling solutions through the use of geothermal heat pumps.”
That number of geothermal systems would require over 50 times the number of wells dug by the entire US oil and gas industry, which itself would be a bonanza of skilled trade jobs. At a time when the incoming US president is focusing on green energy initiatives that create good paying jobs, the idea seems custom made to realize his policy goals.
How to rapidly decarbonize the heating and cooling of buildings is a problem that has not gotten nearly enough attention and is not exactly awash in solutions, Vox says. Geothermal is such a solution, right beneath our feet. We just need to get digging — and using the technologies already developed by the oil and gas industry to lower carbon emissions rather than add more greenhouse gas pollution to the atmosphere.