How would it be if the ground beneath your feet contained more energy than the sun or wind could offer? New research suggests that it does. Beneath some parts of the U.S., at great depths, superhot rock formations could potentially contain about 62,000 TWh of energy. These numbers were developed from serious modeling by the Clean Air Task Force and the University of Twente, not from the imaginings of science fiction.

How the experts measured it: CATF and University of Twente study

The primary data originates from the “heat-endowment” model developed by CATF and the University of Twente, which is the first effort to estimate how much geothermal energy may be in superheated rock formations across North America.

According to the report, using only 1% of superhot rock in North America could produce about 7.5 terawatts, or over 62,000 TWh of electricity. To give you an idea of what that looks like, that’d be enough power for almost 2,700 cities the size of Toronto that use about 23 TWh of power a year,  a fascinating amount of consistent and clean energy.

It is essential to keep in mind that these data are estimates of readily usable resources and are estimations based upon models. The study’s estimates of mineral resources, as they refer to resource estimates with the use of the term “potential”, will depend on the assumptions of geological conditions, depths (mostly below 12.5 km), and certain advancements in technology in the future. 

Four states are leading the way in underground geothermal energy

California, Nevada, Oregon, and Utah represent four states in the United States with the best conditions to use superhot rock energy. These conditions may include high heat flow, a thin crust, tectonic or volcanic activity, and, in some cases, shallower depths, which may be beneficial for accessing superhot conditions.

As an example, Oregon is already the location of a pilot project (Mazama Energy at Newberry Volcano) studying the development of enhanced geothermal systems using superhot rock. This type of project will help test whether wells can reach the required depths, sustain higher temperatures (>~400 °C), and successfully circulate fluid/steam for electrical generation, like this groundbreaking investment dethroning hydrogen worldwide. 

These four states all face their own unique challenges (depth of drilling, type of rock, and the regulatory environment), yet the potential that these states, as the CATF or University of Twente model says, is tremendous, especially if only a fraction of the resource can be utilized.

What it will take to turn superhot rock into a reliable energy source

In order to reach superheated rock, the drilling would be done through hard, faulted rock up to 10 km depth, seeing extreme pressure and heat. Engineers face harsh conditions designing equipment and parts to operate safely at temperatures exceeding 400 °C with induced thermal expansion and contraction, fluid movement, leaks, induced seismicity, and many other rigorous demands.

Economic, regulatory, and funding challenges to unlocking underground energy

Even with favorable geology, cost remains a significant barrier. First-of-a-kind projects are expensive, but costs will continue to improve as technology matures. There is also policy support, permitting, environmental regulation, and the perception of these technologies and resources.

Financing for research and development and pilot projects would need to be coupled with the scale-up process, and must consider water use, land use impacts, and possible ecosystem impacts.

A new study suggests that America could mine superheated rock several miles down for a mind-blowing 62,000 TWh of energy, with the highest potential in California, Nevada, Oregon, and Utah. There are still technical factors, deep drilling, regulation, and capital to address, but if they could be solved, it would provide a zero-carbon and always available energy source that is simply unprecedented, just like this historic miilestone by America.