Long renewable energy’s black sheep, this multitasking energy source has a bright future but only if geothermal developers can dispel the myths around it while lowering the risks to development.  While wind and solar continue to gain in popularity, a new project in Bavaria is showing that heat from the Earth’s core can lead the way. Paul Hockenos shows us how.

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Bavarian innovation

Along a stretch of highway just outside the Bavarian market town of Holzkirchen lies an unremarkable cluster of five, two-story, wood-paneled buildings. As they pass by on their way to Munich, commuters from the affluent towns tucked into the Alps’ foothills might not notice the new Geothermie Holzkirchen facility at all.  A heat and power plant that occupies about two football fields of land, it emits neither noise nor air pollution.

The Holzkirchen geothermal power plant is one of a half-dozen such unobtrusive facilities south of Munich proper, a metropolis of 1.5 million that intends to be the world’s first city of its size to heat most of its homes and businesses with geothermal energy. Planners aim to make its entire heating system carbon-neutral by 2040. Some of the envisioned plants, much like Holzkirchen, will be situated on Munich’s outskirts — where district heating grids will be linked with the Bavarian capital. Other plants will be built directly in the heart of Munich’s busy downtown.

Until now, geothermal energy — basically hot water or steam drawn from the Earth’s sub-soil — has lingered on the margins of the robust rollout of renewables in Europe where, as in most of the world, solar and wind power dominate the landscape. In contrast, geothermal remains a pricey and capital-intensive investment. Additionally, the danger of triggering earthquakes when utilizing deep hydraulic fracking tends to scare off the more cautious.

Regions other than Bavaria have also struck out on their own. Beginning in the 1970s, Paris, which also sits on auspicious geology, provides thousands of households – currently about 900,000 – with geothermal heat. The city, which benefits from generous state subsidizes for geothermal energy, is currently expanding its cache beyond the roughly 50 plants in operation.

Underground History

Both in Europe and globally, however, this is just a fraction of what’s needed. The International Energy Agency (IEA) says that geothermal electricity production has to double to meet international goals. Unfortunately, neither geothermal heat nor power production are thus far “on track”.

Despite employing best practices, it remains to be seen if geothermal’s moment has really arrived. Europe’s energy planners recognize that the contributions of wind and solar power have come largely in electricity production, and not heating and cooling, which together account for almost half of the EU’s energy demand.

“At least in the short term, there’s no alternative to geothermal to replace fossil fuels and nuclear power in decarbonizing the heating sector,” says Thomas Reinsch, a geo-energy expert at the Helmholtz Center Potsdam, a research institute near Berlin.

The discrepancy between geothermal’s nearly endless potential and its middling results have so far left its enthusiasts sputtering with exasperation. “It’s completely irrational that geothermal is so underused,” says Ingo Sass, a professor of geothermal science and technology in Germany and Iceland. “The technology’s there, and economies of scale will follow quickly. Unlike wind and solar, geothermal provides both heat and cooling, as well as base-load power generation, and does so 24/7.” Sass notes that geothermal storage – the storing of hot and cold water in underground aquifers — is also coming into play. Additionally, says Sass, geothermal is not dependent on the sun shining or the wind blowing, making this energy from inside the earth a reliable workhorse and just what decentralized systems based on intermittent renewables require for stability.

Philippe Dumas, director of the European Geothermal Energy Council, explains it another way: “The problem is you can’t see it,” he says. ” Most people just don’t know it’s there, even when it’s heating their homes.”

Starting small

The Holzkirchen plant offers some insights into the complexity and profitability of geothermal power. Beginning in 2002 as a community energy project financed by the town of just 17,000, the idea was developed by the municipality, not by a utility, private developer or investment bank. Holzkirchen had long been an enthusiastic participant in Germany’s Energiewende, or clean energy transition, and was eager to explore a new frontier after years of rolling out solar power and bio-energy.

From the beginning the undertaking was also a calculated business endeavor, but the €40 million price tag was way beyond its means. However, a government price support scheme for geothermal power guarantees Holzkirchkirchen Geothermal an above-market price for the electricity it produces for 20 years. That was the iron-clad pledge the banks needed to sign off on the loans.

A professional forest ranger, Holzkirchen’s deputy mayor Robert Weichmann backed the high-risk, capital-intensive – and, he admits, nerve-wracking — project from day one — over eight years before it generated a single kilowatt hour of energy. The municipality knew that it was taking a huge risk as it had to prove that the geological conditions were right before it could design a business model and apply for bank loans.

“The feasibility study took ages, and then just about everything went wrong that could go wrong when drilling a well this deep,” he says, noting that Holzkirchen’s well reaches over 5 kilometers into the ground, the deepest in all of Europe. The drill heads broke and got stuck. Later drillers hit a gas bubble which needed to be circumvented, says Wiechmann. Inserting the deep well pumps thousands of meters underground, used to pump geothermal fluids to the surface, was also frequently held up.

Yet, despite the myriad obstacles, today Geothermie Holzkirchen is generating heat and electricity. The project should swell Holzkirchen’s coffers to the tune of over €8 million a year.

The technology is not overly complicated, Wiechemann notes. The drilling relied upon an old-fashioned rig, the kind petroleum companies have used for decades to drill for oil. The plant’s heart, he shows me, is the well, a single vent with built-in underground pumps that force the 311 degree (F) water to the surface.

With the technology ready to go, “it’s all about making a convincing business case for geothermal,” explains Reinsch. “Policymakers have to design pricing systems that make it pay to generate heat from renewables, not just electricity,” he says. “Governments have to do for the geothermal heat branch what they did for wind and solar.”