From Supercritical Temperatures to a Fully Decarbonized Grid: A Guide to Geothermal Energy

Picture this: you're at a dinner party, and the conversation turns to the latest developments in clean energy. As the resident energy nerd, you casually mention that geothermal energy is the hottest renewable energy source. Your friends look intrigued, and one asks, "Geothermal? Isn't that just for hot springs and spas?" You smile, knowing this is your chance to break it all down.

First, you hit them with a fun fact: The Earth's core is as hot as the sun's surface - about 10,800°F. Geothermal energy taps into this incredible heat beneath our feet. You explain that while humans have used geothermal heat for centuries for cooking, bathing, and keeping warm, we've also used it to generate clean electricity since 1904.

You mention that the world’s largest geothermal field has 22 power plants. The Geysers in California (which, by the way, are not natural geysers), use naturally occurring hot water and steam near the surface of the earth to generate electricity. But then you lean in and say, "And that's just the beginning. The real potential lies miles underground."

Harnessing Power Beneath the Earth's Crust

You tell them about the advanced technologies companies are developing to access this deep heat:

Enhanced Geothermal Systems (EGS), like those developed by Fervo Energy and Sage Geosystems, create artificial reservoirs by fracturing hot, dry rock and circulating water to generate steam.

Advanced Geothermal Systems (AGS), like Eavor's Eavor-Loop, use sealed pipes to circulate fluid and absorb heat without needing water or fracturing.

As your friends nod along, you casually drop another fact: The hotter the rock, the more power you can generate from each well. You tell them about startups like Quaise Energy and GA Drilling targeting "supercritical" temperatures above 400°C (752°F), where water behaves like a cross between a liquid and a gas, holding much more energy per unit mass. Supercritical geothermal could potentially provide terawatt-scale power.

Your friends are impressed. Well, a few of them. So you keep going, knowing you can blow their minds:

• The heat contained in just the upper 10 kilometers (6.2 miles) of the Texas subsurface is approximately one million exajoules. That is the equivalent of 163,000 billion barrels of oil, or one million times the electricity that the entire state of Texas generates annually. (More about this can be found in The Future of Geothermal in Texas)
• A geothermal plant in Iceland provides 30% of the country's electricity thanks to its location on a hot spot of volcanic activity.
• Boise, Idaho, has been heating homes with a geothermal district heating system since the 1890s, tapping into a naturally occurring geothermal aquifer.

The Future of Global Energy

People are still digging the vibe, so you begin to explain why geothermal energy is such an exciting prospect for clean energy. It's a renewable baseload power source, available 24/7, unlike intermittent wind and solar. Geothermal plants have a small land footprint and are resilient to weather disasters. The hot water can even be used to heat buildings directly, opening up opportunities to decarbonize the heating sector.

The Devil’s Advocate (a friend you love to debate) is standing right in front of you now, asking after legacy systems like oil and gas. You’re excited about this part. You agree with her that the industry’s challenges are robust: high drilling costs, potentially expensive infrastructure, global education and adoption. But geothermal startups like GreenFire Energy and Sage Geosystems are founded by former oil and gas engineers and executives looking to apply their drilling expertise to a renewable energy industry. Companies like these can even repurpose existing oil and gas wells, in some cases.

She looks a little incredulous, so you note that the government is supporting this cross-industry collaboration through initiatives like GEODE (Geothermal Energy from Oil and gas Demonstrated Engineering). GEODE aims to accelerate the growth and development of geothermal by leveraging the oil and gas industry's extensive experience in drilling and subsurface engineering. By bringing together geothermal and oil and gas experts, the GEODE seeks to drive down costs, accelerate innovation, and position geothermal as a central component of a clean energy future.

You can tell you’ve got a few folks considering new ideas. As the conversation winds down, you leave them with a final thought: With exciting technology developments and growing interest from policymakers, investors, and the public, geothermal could be a game-changer in the transition to clean energy, complementing wind and solar to build a stable, fully decarbonized grid.

As you sit back and take a sip of your drink, you feel a sense of satisfaction. Not only did you impress your friends with your geothermal knowledge, but you may have just inspired a few more people to join the geothermal revolution. And who knows, maybe at the next dinner party, they'll be the ones excitedly sharing geothermal facts that nobody asked for.