When we think about the impact of fossil fuel energy and the short-term alternatives at scale to liberate today’s energy mix from geopolitics or climate constraints, we hear about the advance of solar and wind in China, India, and the developed world and how running solar farms to make electricity at scale can be now cheaper than running and maintaining coal-powered plants.

We also hear, though much less so, about efforts to develop small modular reactors that try to diminish the risk and multiply the advantages of nuclear power, due to the traditional opposition to nuclear power (which, nearing Christopher Nolan’s Oppenheimer premiere in cinemas, we should be ready to disassociate from military uses and previous disasters) and a high up-front cost, compared to traditional energy and solar power generation.

We have learned to tap into the nuclear reactions that have powered the Sun for more than 4 billion years, either by harvesting small amounts of solar radiation through solar thermal and solar photovoltaic cells or by using a more rudimentary form of atomic reaction to create emission-free energy locally through nuclear power plants (unlike nuclear power on Earth, the Sun operates in “fusion” mode, one of the energy dreams of the coming decades).

By looking at heat radiation beyond us, we forgot what’s underneath

The Sun allows life on Earth. No wonder it also inspired some of mankind’s oldest known deities (to the Sámi’s traditional animist worldview, for example, the Sun and the Earth existed first, the Sun being the father of all that exists, and the Earth, the mother). However, we are much closer to a very hot celestial core in space that could conceal a gigantic opportunity to generate cheap carbon-free power.

One of the Solar System’s rocky planets, Earth, is made up of layers. Its inner core reaches up to 10,800 degrees Fahrenheit (6,000 °C). The mantle is mostly solid rock, with weaker areas of friction where the outer crust sheets conforming entire regions and continents clash. It’s where plates meet or separate, or around supervolcanoes like Yellowstone, that Earth’s heat reaches the surface. But drilling technology could allow a massive use of geothermal energy in vast areas where the crust is thin enough for pipes to tap into the contained, constant heat coming from the core.

What is preventing us from exploring ways of harvesting Earth’s inner magma reactions and transforming them into power through dedicated plants on our surface? Our limitations seem to be more conceptual than technological. By looking up and trying to transform a growing problem on Earth (more sun radiation) into the energy that should accelerate decarbonization at a big scale, we conceptually elude, like our ancestors, another virtually endless, untapped energy much closer to us: geothermal energy, or the heat escaping into the surface that generates our very own planet. We are sitting on a geothermal power plant, yet we insist on burning the stored caloric energy of fossilized organic matter buried in sediments.

Adding high-scale geothermal power to the mix?

Did our perceived dependability from the Sun make us forget that, underneath the Earth’s soil fecundity, which Stone Age people celebrated burying figurines of fertile women, there’s an immense amount of energy disguised in heat? Or have we been missing a technological breakthrough to transform this energy, only of easy access in areas where the subsoil is particularly hot below the surface?

Humans have used hot springs for bathing since at least Paleolithic times. Ancient China and Rome developed networks of hot springs and thermal baths, albeit technological constraints determined that the only geothermal heat exploited was that found abundant on the surface, thanks to volcanic activity around tectonic plates. In North America and Mesoamerica, ancient natives settled near hot springs.

In Eurasia, thermal water areas were worshiped. Ancient Chinese kingdoms built palaces and temples above naturally heated pools. On the other extreme of the Silk Roads, during Roman times, Aquae Sulis (Bath, England) thrived with public baths and underfloor heating, a pioneering use at the scale of non-converted geothermal power. A similar system has powered the heating pipes network benefiting the Chaudes-Aigues inhabitants in Central France’s highlands, albeit this time extended to a whole town. The pipes carried water from a local hot spring, delivering it to homes, still in use nowadays, 700 years after.

The first attempts to use geothermal pipes to propel big facilities came with the Industrial Revolution. In 1904, Piero Ginori Conti tested a generator powered by geothermal steam in Italy. After the success of his first experiment, he built a local power plant in 1908. The technology has not evolved much since Piero Ginori’s time, and, even though over 30 countries have geothermal power plants today, the technology is still marginal among the also marginal (though growing exponentially in countries like China) share of energy generation with renewable sources.

Geothermal tech just got boosted

Up until now, only three main methods of using heat from the Earth’s core were viable: steam-powered turbines to spin a generator that generates energy, direct heat (used since prehistory and exploited at a big scale in Iceland), and geothermal heat pumps (which rely on the constant soil temperature underground).

Such methods have developed in Europe and around the so-called Ring of Fire. This tectonic perimeter encircles the Pacific Ocean, hearing groundwater trapped in fractured or porous rock and faults.

Things may have changed this week. Houston-based small energy company Fervo Energy announced on July 18 that it had reached an expected technological breakthrough ahead of time: they hoped the technique was expected to be commercially available by 2035, but things changed recently when their drilling adapted from the oil industry completed a well that performed better than expected over a 30-day test.

The company drills deep wells to reach the Earth’s mantle almost from anywhere, then pumps water into the well created; the water grows hot from the planet’s inner heat, then Fervo pumps it back to the surface, where a turbine converts the heat to electricity.

The new technique, which can drill both vertically and sideways, could represent an opportunity for geothermal energy to become mainstream beyond its traditional tectonic boundaries, becoming an alternative to renewables. The most optimistic in the sector believe that modern civilization could create a decentralized network of geothermal power plants that could both power and cool industries and households with pervasive (and therefore more and more affordable) heat pumps.

Once filled with water, Fervo Energy’s test well reached a constant temperature of roughly 375 degrees Fahrenheit; to do so in Northern Nevada, the company had to drill down 7,700 feet, then 3,250 feet horizontally, to create the infrastructure, capable of generating 3.5 megawatts of electricity, enough to power over 2,500 homes.

Geothermal power plants beyond tectonic boundaries

Why does Fervo’s CEO Tim Latimer believe the company has reached a significant milestone? Their combination of deep drilling with heat pumps for power generation using water warmed by the Earth’s mantle means that such facilities could be built virtually anywhere instead of exclusively on tectonic boundaries such as Iceland, some areas around the Mediterranean Basin, or the Ring of Fire around the Americas’ West Coast and Asia/Oceania’s East Coast.

Latimer says that another thing has changed, which was made possible by technological innovation in the oil prospection industry:

“Geothermal has long been held back by drilling costs. We just got a lot better at drilling.”

Instead of relying on optimal conditions (surface geothermal in fault areas), the company uses hydraulic fracturing to create geothermal reservoirs in formerly ineligible places. The opportunity for growth is massive: geothermal energy supplies marginal amounts of energy to countries lucky enough to be on tectonic boundaries. In the US, only 0.4% of the energy produced comes from geothermal power.

Executives at the energy startup aren’t the only ones encouraged by this week’s milestone news. Jesse Jenkins, a macro-scale systems engineer and professor at Princeton, published an optimistic statement on it.

“Fervo’s successful commercial pilot takes next-generation geothermal technology from the realm of models into the real world and starts us on a path to unlock geothermal’s full potential.”

Where the current energy mix is coming from

During the New Deal years of the interwar period and after WW2, statism prevailed both in the Western and the Soviet Blocs, and the world experienced a spike in dams for hydroelectric production, as well as other pharaonic projects capable of generating temporary economies in depressed areas. This trend propelled the transformation of rivers interrupted by dams powering hydroelectric plants, sometimes catastrophically.

Later, megaprojects of river subjugation to generate energy became the dream of the developing world during the turmoil years of decolonization. However, fossil fuels prevailed as the centerpiece of international politics and influence abroad of the old colonial metropolis and the two Cold War superpowers.

British historian Peter Frankopan reminds us in the last chapters of his essay The Silk Roads that what the West perceives as buffer regions between Europe and the Asia-Pacific region has always determined the rise and dawn of empires and superpowers; Arabia and Central Asia regained the centrality they had in the past when the British found oil in the region and other powers, including the United States and the Soviet Union, would dedicate their resources to impose their interests and vision of the world.

Yet the 1973 oil crisis represented a warning to the world’s dependence on oil and gas. As a consequence, and during a short period, governments, companies, and citizens shared the incentive of investing in energy efficiency and non-dependent energy sources such as solar power. At the moment, only oil prices represented an incentive to develop fossil fuel alternatives, and only a few scientists worried about “tragedy of the commons” externalities at a global scale, such as overfishing, the Ozone layer, the greenhouse effect, or acid rain.

At least things changed fast for the ozone layer after atmospheric research published in 1976 revealed that the layer was being depleted by chemicals such as CFCs. Things would prove much more complicated for the other issues.

The long resonance of an oil embargo

The oil crisis during the convoluted 70s’ also increased the production and use of coal for energy generation, despite more restrictive legislation in the US and Europe about its use near cities like the Clean Air Act; extreme pollution events, like London’s Great Smog in December 1952, had helped in restricting the use of coal in the West, though it remained the primary source in the Eastern Bloc and the Asia-Pacific region to this day, despite the fall of the Iron Courtain and the EU integration of most former members of the Warsaw Pact.

The public needed chained event of massive fires around Quebec and other Eastern Canadian provinces caused smog clouds so thick and hazardous for human health across the US Northeast and Midwest, to remember how bad air quality was in urban America before the Clean Air Act of 1970. The regulation led to curbs on soot, smog, mercury, and other toxic chemicals. Today’s developing countries experience sustained rates of air urban pollution only seen in the developed world during fire season. Due to their electric grid unreliability, entire regions in Asia, such as India’s most populated areas, depend on the use of gas-powered generators that increase already toxic air.

The first boom in home solar thermal and electric systems came in the late seventies in places such as California and Western Germany, and it lasted for as long as OPEC succeeded in maintaining onerous-enough oil prices. But hyperinflation and social turmoil had more weight in the collective unconscious than long-term planning. Carter had installed solar panels in the White House and created a renewable energy plan for the US in 1979. One year later, amid the Iran hostage crisis, Carter lost the presidency in a massive landslide.

Soon, everybody had forgotten about energy efficiency and small-scale renewable sources of energy decades before the boom of local shale oil production in North America for geopolitical and energy security reasons. Americans old enough to have lived back then aren’t generally fond of Carter’s years; the cycle—and people’s mood—changed with Reagan.

Iceland’s most interesting attraction

The context explains, at least partially, why both in the 70s and nowadays, a potentially inexhaustible power source remained unnoticed despite its potential for big-scale heating and energy generation in vast areas of the world: geothermal energy. One could symbolically install solar panels and promote renewables as a partial, incomplete solution to reduce fossil fuel dependency, which still holds today given solar PV low conversion rate of sunlight to usable energy (from less than 10% at the time to around 20% today).

The 70s oil crisis encouraged transformative changes in other countries dependent on energy imports and concerned by urban air quality, some of whom turned a dire situation into an opportunity to perform a transformative transition. Iceland, once among the poorest countries in Europe, relied on coal and oil imports for energy. Then the 1973 oil embargo hit the country’s reserves hard. Black smoke was an issue in Reykjavík until 1973 (when Iceland was getting 75% of its power from this source).

But, instead of paying higher prices and increasing their sovereign debt, Icelanders decided to boost their geothermal investment. With over 200 active volcanoes sitting between two tectonic plates slowly pulling apart, the heat rising to the surface—they figured—could power and heat the entire population.

First, households and neighborhoods started piping steam to heat buildings; then, they built geothermal power plants for electricity. The cost went down, as did pollution too. Five decades after, more than half of Iceland’s homes use geothermal energy.

With new breakthroughs, such as the drilling milestone by Fervo Energy, virtually any region with enough public determination and popular interest could start a transition to a mesh system of geothermal heat pumps for mass HVAC.

Given the evidence, one question will arise sooner than later: could we use a decentralized, planetary-scale heat pump to cool the atmosphere using geothermal energy?