Geothermal Networks Use the Heat Under Our Feet

Icelanders tap their volcanic endowments for heat and power. The country is one of a handful already providing 100 per cent clean power, while 90 per cent of its homes are heated with geothermal energy and electric vehicles are fast approaching half of all new sales. You can even rent one from a company called Lava Car Rental.

Volcanism has its downsides — just ask the Icelanders forced to evacuate recently to escape the lava flows. Thankfully, tamer versions of geothermal energy are available and they’re heating up the world of climate tech.

Confusingly, all of them are referred to as “geothermal” even though they are totally different approaches to energy, other than the use of underground pipes.

The heat under our neighbourhoods

You’ve probably heard of private developers or campuses tapping heat at relatively shallow depths where the ground holds the sun’s warmth all year round. No flirting with lava or drilling deep to hot rocks. Just bore some holes or tap into a water source, run some pipes, fill them with fluid, tack on a heat pump and you’ve got heat. Crucially for our climate-changing world, you’ve also got cooling.

They’re technically called “ground source” heat pumps, sometimes “geothermal heat pumps” or “geoexchange systems.” Occasionally even “earth-coupled” (delightful and vaguely titillating — that would have my vote but seems unlikely to win the broader naming competition).

They work. In fact, they’ve been around since the 1950s. No more burning gas in homes and heat pumps are beyond efficient — ground source heat pumps give back four to five units of energy for every one you put in. "The closest thing to a silver bullet" in the race to clean energy, says the head of the International Energy Agency.

And … they’re very expensive to install on your own.

But very smart people are rolling them out under whole neighbourhoods in a version of district heating known as a geothermal network, where a few boreholes supply a community, distributing the system cost while providing heating and air conditioning to multiple buildings. In New England, studies show networked geothermal to be cheaper than gas or air-source heat pumps and scalable across the region.

In Massachusetts, the gas company even got on board. National Grid and Eversource are regional utilities installing the first geothermal networks. There’s a real logic for the utilities. After all, the system looks a lot like what the gas utilities have been doing all along — a network of buried pipes serving neighbourhoods — replicating the gas network but without the gas. Instead of fighting decarbonization, it’s a chance for the gas company to embrace clean energy, transform itself and avoid a death spiral.

To its credit, National Grid was already moving on trial projects before the State of Massachusetts mandated a move away from gas. New York and Colorado have also passed laws requiring gas utilities to build geothermal networks.

Geothermal networks are one of those brilliantly obvious ideas, once you hear about them. Even better to discover the idea is already well-tested and deployed. I had never heard about Kensa before this week, but the company has been quietly manufacturing and deploying ground source heat pumps across the U.K. for two decades.

By its reckoning, “Kensa has saved over one million tonnes of carbon through ground source heat pump installations.”

 Image from Kensa

Don’t feel bad if you've never heard of Kensa. For a long time, neither had the author of the U.K.’s world-leading Climate Change Act. Bryony Worthington sat down with Kensa’s new CEO to get caught up on the company’s recent injection of £70 million (about $118 million) from investment company Legal & General Capital and energy supplier Octopus Energy.

You can hear all about the plan to install 50,000 ground source heat pumps per year by 2030 in Worthington’s interview on YouTube or as a podcast.

 Image from Kensa

Deep heat

Far deeper than the cosy warrens of networked geothermal, things get really hot. And a number of companies are repurposing oil and gas expertise in deep, horizontal drilling to tap those high temperatures.

This kind of “enhanced geothermal” is a much trickier proposition than ground source heat pumps. It’s a wild card but could supply vast amounts of carbon-free energy 24/7. How vast? In the U.S., it could plausibly power 65 million homes to the Department of Energy. And those calculations are based on the industry’s performance up to 2022. The results are markedly better now, so it’s worth checking in on a couple of examples.

We’ve covered Alberta-based Eavor Technologies in past newsletters. Eavor drilled deeper than five kilometres under New Mexico last year, grinding through hard granite to temperatures around 250 C.

The company originally proved its technology for an underground closed-loop “radiator” near Rocky Mountain House but it was Germany that took it to commercial scale with a project now under construction near Geretsried, south of Munich. That Eavor project is designed to produce both heat and electrical power.

You might recall that Alberta’s environment minister went to Bavaria for the ground-breaking ceremony with the German chancellor. Awkward, since Alberta had just put a freeze on renewable energy projects. Last year, Eavor successfully raised $239 million in equity capital to scale up, including $90 million from the feds’ Canada Growth Fund. In addition, the European Union came in with €91.6 million ($134 million). Even the United States Air Force signed a contract.

In November, another enhanced geothermal company, Fervo Energy, began supplying electricity to the Nevada grid from a project backed by Google.

Tim Latimer, Fervo’s CEO, says the project “proved commercial readiness over a decade ahead of most forecasts.” It prompted the MIT Technology Review to name enhanced geothermal a “breakthrough technology” for 2024.

Then on Monday, Fervo revealed it can now drill deep, horizontal wells 70 per cent faster and 50 per cent cheaper than one year ago.

“We’ve now shown we can develop highly productive enhanced geothermal wells, slash development costs and deliver incredible performance drilling granite at more that 430 F,” said Latimer. “Hotter, deeper, faster, cheaper. The Geothermal Decade continues.”

[Top photo: Steam rising from the Nesjavellir Geothermal Power Station in Iceland]