Clean energy has become synonymous with wind and solar, and with good reason. Thanks to improved technology and declining costs, wind turbines and solar panels are producing a rapidly growing share of the world’s electricity.

But there are many other sources of clean power that could provide abundant, emissions-free energy and help replace fossil fuels. This week, my colleague Brad Plumer took an in-depth look at one of those tantalizing technologies: geothermal power.

Traditional sources of geothermal power are well established. For more than a century, people have been using steam produced by underground heat to power generators. Iceland and New Zealand generate about 20 percent of their electricity from geothermal.

But those countries are the exception. In most parts of the world, steam doesn’t conveniently come out of the ground right where it’s needed. (Geothermal power produces less than one half of one percent of America’s electricity.)

That could soon change. A new class of start-ups is investing in the industry, as is the U.S. Energy Department, which estimates there’s enough energy in the rocks below the surface to power the entire country five times over. And much of the research and development needed for the new geothermal technologies is already done, thanks in large part to recent advances by the oil and gas industry — including fracking.

How’s that for irony? At the end of the day, it might be techniques developed by Big Oil that ultimately help make fossil fuels obsolete.

Drilling, but not for oil

Over the past 20 years, fossil fuel companies have gotten very, very good at drilling.

“It’s something that climate people never like to talk about,” Brad told me. “But the cost of drilling has gone down. The oil and gas industry has drilled thousands and thousands of wells and every time they get a little better.”

By using new techniques like horizontal drilling, fiber-optics and magnetic sensing, some experts think it might be possible to tap into geothermal energy almost anywhere on earth.

“The thing that made me think that this could be real is the fact that the major costs of these geothermal projects often is drilling,” Brad said. “And drilling is not something we have to learn to do from scratch. Drilling is something the United States has just gotten incredibly good at.”

In his article, Brad spoke with Tim Latimer, the co-founder of Fervo Energy, which is using an old oil rig from North Dakota and fracking techniques — similar to those used for oil and gas — to crack open dry, hot rock and inject water into the fractures, creating artificial geothermal reservoirs.

“There’s a virtually unlimited resource down there if we can get at it,” Latimer said. “Geothermal doesn’t use much land, it doesn’t produce emissions, it can complement wind and solar power. Everyone who looks into it gets obsessed with it.”

Obstacles ahead

The industry is facing plenty of challenges.

Investors are still cautious about putting too much money into an industry that has not proven the ability to scale. Permitting for the projects is difficult. Underground geology is complicated. Federal support for the industry pales in comparison to its support for fossil fuels and other sources of clean energy. Drilling for geothermal energy can create some of the same problems as drilling for gas: sucking up water and causing earthquakes.

Still, the urgent need to find new sources of clean energy combined with the advances in drilling are creating a moment for geothermal. Fervo said last month that it had achieved a key milestone at a pilot plant, and it is building a large-scale facility that would power 300,000 homes. Another geothermal start-up, Eavor, is now drilling wells for its first commercial plant in Germany to provide heat and power for the country, which is trying to sharply reduce its reliance on gas.

“The fact that people are building things makes me feel like this is a little less pie in the sky than other technologies,” Brad told me. “But there’s still a long way to go from demonstrating that this is possible to actually making it a widespread reality.”

Europe slashes its use of fossil fuels

Fossil fuels made up only 33 percent of the European Union’s electricity in the first half of this year, a record low, according to a new report by Ember, an energy think tank.

The slump in use of dirty energy sources is mostly a consequence of high gas and coal prices, which have curbed demand across Europe. Prices have fallen since the peak of the energy crisis created by the war in Ukraine, but are still high enough to curb industrial activity.

Prices are not likely to go down any time soon, but demand could go up for other reasons, like a harsh winter. That could make fossil fuel use rise again in the short term. But what will happen in the long term is still unclear.

“It’s an open question to which degree this is cyclical or structural,” said Matt Ewan, the report’s author.

Longer-term trends are at play. Take coal, for example. There was a concern after the war started that countries would roll back their attempts to phase out coal. That didn’t happen. Coal use fell by 23 percent in the first half of 2023. This was partly because high prices led to a slump in demand, but this decrease in coal use is projected to continue as more coal-powered power plants close.

The record numbers are also the result of a push by countries in Europe to accelerate the energy transition. Seventeen of the European Union’s 27 countries generated record renewable power in the first half of 2023. Generation from clean sources — wind, solar, hydropower and nuclear — increased across the region.

Ember’s report said this transition still needed to happen even faster. That will become crucial as energy prices stabilize and efforts to electrify cars, trucks and other sectors pick up steam, increasing demand for electricity.

The weather report

As the remnants of Hurricane Idalia battered the Carolina coast, and as Hurricane Franklin churned far off in the Atlantic, Tropical Storm Jose formed early today. Forecasters expect that it will be absorbed by Hurricane Franklin by the weekend.

Yes, one storm can absorb another: Think of it less like Pac-Man eating a ghost and more like a sponge absorbing water.

Idalia is forecast to continue pulling away from the East Coast today, moving toward Bermuda as a potential tropical storm. Forecasters warned of “significant uncertainty” about its path beyond this weekend. — Judson Jones