Geothermal energy provides one of the cleanest and most consistent sources of renewable energy on Earth. In theory, there is enough geothermal energy under the Earth’s crust to sustainably power the entire planet – so why aren’t we using so incredibly little of it? The issue is tapping into that radiant heat – only a tiny fraction of the Earth’s thermal energy can be accessed profitably. But a team of researchers out of MIT thinks they may have achieved a technological breakthrough with the ability to tap into a whole lot more of the Earth’s geothermal energy potential.
Currently, geothermal energy is almost exclusively produced where heat from the Earth’s core bubbles up to the surface, such as where there are naturally occurring geysers and hot springs. For this reason, geothermal accounts for a mere 0.5% of renewable energy on a global scale. Its share of the broader energy mix, including fossil fuels, is infinitesimal. Raising the bar for geothermal energy production will require the ability to drill much, much deeper into the Earth to tap into radiant heat from the Earth’s core, and to do so efficiently and affordably.
This is no small feat. “To grow as a national solution, geothermal must overcome significant technical and non-technical barriers in order to reduce cost and risk,” says the introduction to a 2019 U.S. Department of Energy (DOE) report — GeoVision: Harnessing the Heat Beneath Our Feet. “The subsurface exploration required for geothermal energy is foremost among these barriers, given the expense, complexity, and risk of such activities.”
However, in recent years, scientists have made major strides toward scalable ‘enhanced geothermal systems’ that pull heat from the depths of the Earth. According to a 2023 report from Esquire, this technology will “allow us to exploit the energy underfoot across the country, all with a carbon impact that is vanishingly small compared to most sources we depend on now.” This is not limited to the United States. The promise of enhanced geothermal is that it would be deployable nearly anywhere on Earth.
Early enhanced geothermal projects have had some success employing deep-drilling technologies originally used in fracking. Ironically, the hydraulic fracturing methods that fuelled the shale revolution are now touted as a potential avenue for decarbonization in the United States, and the Biden administration has thrown a considerable amount of money behind pilot geothermal research and development projects such as the Utah Forge project.
But these technologies are only valuable insofar as they are cost-effective, and so far that’s not the case. “For now, federal analysis shows this type of geothermal costs around $181 per megawatt hour, while utility-scale solar costs just $25,” NPR reported last year. However, private-sector geothermal experts anticipate that those costs will drop significantly – reaching an estimated one third of the current price – over the next decade.
But now another breakthrough technology has entered the scene, introduced by a spin-off of MIT. And this time the tech isn’t borrowed from the fossil fuel sector, it’s from an even more futuristic clean energy solution – nuclear fusion. Quaise Energy, based in Cambridge, Mass., has already raised $95 million from investors (including Mitsubishi) to apply gyrotrons to geothermal energy extractions.
Gyrotrons are currently used in nuclear fusion experiments to heat and maintain plasma. But this team argues that they can also be used to drill deep into the Earth farther and more efficiently than ever before, by melting rock with energy beams. Based on the team’s experimenting and mathematical models, it is calculated that “a millimeter-wave source targeted through a roughly 20 centimeter waveguide could blast a basketball-size hole into rock at a rate of 20 meters per hour,” reports IEEE Spectrum. “At that rate, 25-and-a-half days of continuous drilling would create the world’s deepest hole.” Even better, this can be accomplished with the same amount of energy used to power a typical drilling rig.
That kind of speed and depth means that drilling for geothermal would be quicker and cheaper than ever before, with potentially industry-disrupting consequences. “Supercritical geothermal power has the potential to replace fossil fuels and finally give us a pathway to an energy transition to carbon-free, baseload energy,” says Quaise CEO Carlos Araque. “We need to go deeper and hotter to make geothermal energy viable outside of places like Iceland.”
