Can Geothermal Cooling Tame Data Centers’ Energy Appetite?

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The world is increasingly run by data centers — huge, anonymous buildings that gobble up electricity and belch heat like angry dragons. Each click, stream, or swipe piles up more data in racks upon racks of humming servers. Yet few people realize just how thirsty these data dragons really are. About 40% of their electricity goes straight to cooling — essentially, a massive overhead cost to keep their internal electronics from frying like bacon in a pan. That’s millions of kilowatt-hours and millions of dollars down the drain every year.

The technology to slay this dragon is actually hiding right beneath our feet. Geothermal cooling isn’t a futuristic fantasy; it’s basic thermodynamics dressed up in sensible shoes. In simple terms, geothermal systems leverage the Earth’s constant underground temperature at depths of 15 to 250 meters — usually a pleasant 10 to 15 degrees Celsius — to efficiently reject the heat from data center servers. Instead of fighting summer heat waves or freezing winters, these systems rely on the calm steadiness of soil and aquifers deep below. Think of it as sending your server heat down to a giant subterranean wine cellar rather than trying to chill it in a garage on a hot August afternoon.

As a note, this is one in a series of articles on geothermal. The scope of the series is outlined in the introductory piece. If your interest area or concern isn’t reflected in the introductory piece, please leave a comment.

But does geothermal cooling really deliver, or is it yet another clever-sounding clean tech gimmick? Short answer: Yes, but with some important caveats. If you’re building a hyperscale facility — one of those gigantic data farms that power Google, Amazon, or Facebook — geothermal could indeed scale up, but the infrastructure needed is extensive. It’s doable, but you need serious geological luck or an enterprise-scale commitment to sustainability.

Mid-sized enterprise and campus-scale data centers hit a sweet spot, with their consistent thermal loads and space to deploy borefields. Colocation data centers, where multiple tenants share a facility, can also excel, especially when they tap into naturally cool aquifers, as demonstrated vividly by Equinix’s AM3 facility in Amsterdam. Edge data centers — those small, local server rooms cropping up everywhere — could theoretically benefit, but using geothermal for them is a bit like buying a gourmet kitchen to boil an egg: nice, but extravagantly unnecessary.

Geothermal’s upfront costs aren’t trivial. Drilling dozens or hundreds of boreholes into the earth isn’t cheap, but that initial capital shock quickly fades when the savings roll in. Operating geothermal cooling systems generally cost far less than traditional mechanical chillers, sometimes cutting cooling bills by nearly half. In places like Europe, with its high electricity costs and strict environmental rules, the investment often recoups itself in as little as five to seven years. In the US, federal incentives — like the Inflation Reduction Act’s 30% tax credit — can similarly slash that payback period, helping justify the initial wallet-pain. Over the long run, these systems not only pay for themselves, they insulate data center operators against future energy price spikes or carbon taxes that could otherwise devastate profitability.

Yet, even with all these merits, geothermal isn’t a perfect plug-and-play solution. Things can, and occasionally do, go sideways underground. There are risks like unexpected geological quirks, stubborn regulators wary of groundwater impacts, or the simple challenge of drilling holes through rock. The folks at Microsoft’s Redmond campus — where nearly a thousand geothermal boreholes were installed — know firsthand that planning, expertise, and some contingency funds are essential. Operators must plan redundancy carefully: relying solely on any single cooling method, even geothermal, is about as smart as paragliding without an emergency chute (thankfully, I never had to toss mine in mid-air). Fortunately, when done right, these systems prove remarkably reliable, quietly and efficiently humming beneath the surface for decades.

Speaking of timelines, if you’re considering geothermal cooling, prepare to think ahead. Realistically, from initial feasibility studies through design, permitting, drilling, and final integration, expect about two to three years of project time. Yes, that’s longer than popping in standard chillers, but it’s time invested in predictable energy costs and superior sustainability. Waiting until your racks are overheating isn’t exactly a prudent cooling strategy, unless your business model includes scrambling desperately for emergency chillers at premium prices.

One of the more delicious ironies in the energy transition is that the fancy toys built for fracking — horizontal drilling, steerable drill heads, high-res subsurface imaging — are now being repurposed to make shallow geothermal boringly bankable. The shale boom didn’t exactly gift the world with climate solutions, but it did force an entire industry to build out precision drilling tech like it was going out of style. And now? That same tech is being ported over to shallow geothermal, derisking projects that used to look like geology roulette.  Instead of wildcatting for hydrocarbons, these rigs are now punching precise, low-temp wells into city blocks and campuses, much more quickly than the legacy drills that have dominated until recently.

Let’s look at who’s getting this right, because successful examples abound. Epic Systems, nestled comfortably in Wisconsin, drilled over 6,000 boreholes to create one of North America’s largest geothermal cooling networks, comfortably cooling a 3.5-megawatt data center while simultaneously heating their expansive campus in winter. Across the pond, Equinix’s Amsterdam facility uses aquifer thermal energy storage brilliantly, taking advantage of Europe’s progressive water-management policies. Their data center’s cooling water is borrowed from a naturally cool aquifer, quietly and efficiently providing 12 megawatts of free cooling capacity — an elegant solution, perfectly suited to local geology. Meanwhile, Microsoft’s Redmond project showcased not just scale but ingenuity, delivering reliable heating and cooling for buildings and labs via a network of underground heat-exchange loops. Clearly, geothermal isn’t merely viable — it can be transformative.

Of course, the geothermal that’s getting all the attention today is the generation of electricity from much deeper, higher risk and higher cost geothermal. ​Fervo Energy has inked a 30 MW geothermal electricity contract with Google, aimed at powering their data centers. This collaboration began in 2021 with the development of next-generation geothermal power to supply Google’s Cloud region in Las Vegas. ​As I noted in the article on enhanced geothermal systems — aka fracking for heat — even the optimists think it’s only going to eventually get down to $150-$250 per MWh, and Fervo’s electricity is likely in the $300-$400 range. By contrast, wind and solar, even firmed by batteries, are in the $45-$100 range. EGS and other electrical generation geothermal plays are the nuclear of geothermal, taking a lot longer and a lot more time with a lot more risks to create economically inflexible electricity.

Yet despite the successes of data center cooling with shallow, lower risk geothermal, many data center developers remain stuck in old-school cooling paradigms — often due to inertia, caution, or simple lack of familiarity with geothermal technology. It’s time for a change. Developers and operators need to step up, challenge their engineering teams, and start digging — literally. The financial and environmental benefits of geothermal cooling are increasingly hard to ignore, especially as electricity rates climb and sustainability pressures intensify. Likewise, jurisdictions courting data center investments — particularly places like Ireland, already straining under the massive data centers clustered around Dublin — must prioritize geothermal-friendly policies and incentives. Doing so could position these regions as global leaders in sustainable digital infrastructure, rather than reluctant hosts to energy-hungry monsters.

The Irish context is high on my radar screen at present because one of the hats I’m wearing is assisting an emerging Irish NGO focused on clean, affordable, and secure energy for all with strategy sessions so that they can create a focus, and data centers are front and center. Further, I just recorded a two-hour discussion for my podcast channel Redefining Energy – Tech with Irish geothermal entrepreneur Simon Todd of Causeway Energies. For that matter, a firm I co-founded last year to provide rapid digital twins of existing infrastructure increasingly impacted by climate change, Trace Intercept, is incorporated in Ireland, in part because a couple of the other founders are Irish.

Ultimately, geothermal cooling isn’t just a promising technology — it’s an opportunity to fundamentally rethink how we build and run data centers. It’s a practical, proven solution hiding in plain sight, waiting patiently underground. Developers, operators, and policymakers, whether you speak with an Irish accent or not: your next data center can either contribute to the climate crisis or quietly help solve it. All it takes is the willingness to drill a little deeper — not just into the earth, but into a smarter, more sustainable future.