An unlimited supply of heat exists beneath our feet within the Earth’s crust, but harnessing it at scale has been challenging. Now, a combination of new techniques, government support and the urgent need to ensure continuous clean power in an era of climate crisis means that geothermal energy is finally getting its moment in the US.
Until recently, geothermal energy was only viable where the earth’s inner heat simmered near the surface, such as at hot springs or geysers where hot water or steam could easily be drawn to drive turbines and generate electricity.
Although it allowed a limited number of places, like Icelandto use geothermal as a main source of heating and electricity, it had only a niche presence in the US, less than 1% of its electricity. But that could change dramatically, offering the promise of endless, 24/7 clean energy that could fill the gaps of intermittent solar and wind generation in the electricity grid.
“Geothermal has been used for over 100 years, limited to certain geographic locations – but that is now changing,” said Amanda Kolker, the geothermal laboratory program manager at the National Renewable Energy Laboratory (NREL).
“As we enter the grid with renewables that are not available all the time, we need to find a base load that is currently being taken up by gas. There aren’t really many options for zero-emissions baseload power, which is why geothermal energy comes into the picture.”
Geothermal capacity could increase 20-fold by 2050 and generate 10% of US electricity, according to a recent roadmap released by the US Department of Energy. Joe Biden’s administration has also funded new projects aimed at promoting the next generation of geothermal resources aimed at making the energy source available anywhere on America’s landmass, not just easily accessible hot springs.
“The US can lead the future of clean energy with continued innovation on next-generation technologies, from harnessing the power of the sun to the heat beneath our feet, and cracking the code to deploying it at scale,” says Jennifer Granholm, the US energy secretary, who added that she sees “enormous potential” in geothermal terms.
Expanding the geothermal footprint across the U.S. will take time, as well as a lot of money—the Department of Energy estimates as much as $250 billion will be needed for projects to become widespread across the country, providing a major source of clean power supply.
But geothermal advocates say such growth is within reach, thanks to a wave of geothermal technologies as well as government support. In February, the Biden administration announced $74 million for up to seven pilot projects to develop improved geothermal systems that, the government said, have the potential to power 65 million American homes.
Ironically, improved geothermal use makes similar fracking techniques currently used to extract oil and gas, which must be phased out if the world is to avoid climate catastrophe. In the geothermal version of fracking, fluid is injected deep underground, causing fractures to open, with the fluid heating up as it circulates. The hot water is then pumped to the surface, where it can generate electricity for the grid.
This, and other new techniques that allow deeper and horizontal drilling, in some cases up to eight miles deep, allow geothermal energy to be drawn from hot rocks found anywhere underground, rather than selecting spots that have hot water near the surface. has. This greatly increases the potential of the technology.
“If you drill anywhere in the country, it gets hotter and hotter every mile you go deeper,” said Koenraad Beckers, an NREL thermal sciences researcher.
“In the western United States, that temperature is increasing rapidly. If you only drill one to two miles deep, you have temperatures hot enough for electricity. To get those temperatures in eastern states, you might have to drill miles and miles down, but you can use lower temperatures to directly heat or cool campuses, neighborhoods and even towns.”
Dozens of new companies want to go ahead with geothermal plans, driven by incentives offered by recent law succeeded in the US, although only a few have so far managed to complete full projects in the US, such as Eavor, a Canadian firm that successfully drilled a three-mile hole in New Mexico to prove it can access heat in deep, granite rock.
For these companies, an inexhaustible energy supply is at stake. Only one type of next-generation geothermal – called super-hot rock energy, where deep-bore temperatures reach 400C or hotter – is abundant enough to theoretically meet the world’s power requirements. In fact, just 1% of the world’s super hot rock potential can generate 63 terawatts of clean firm powerwhich would meet almost eight times the global electricity demand.
“While this modeling is preliminary, our findings point to an enormous opportunity to unlock vast amounts of clean energy beneath our feet,” said Terra Rogers, the director for superhot rock energy at the Clean Air Task Force, which produced the modeling tool to measure the potential of this approach.
“Energy security backed by always available carbon-free energy is not a distant dream.”
