Decarbonizing Industrial Heat with Deep Geothermal

At the end of the day, producing heat consumes more energy than anything else in the world—even more than electricity and transportation. It accounts for roughly half of all global energy use and more than a third of all global carbon emissions.

Heating is crucial both at home and at work. Luckily, there are a wide variety of options for relatively low-temperature uses, such as ground source heat pumps for buildings. However, industry uses half of all heat, and the low-carbon options for the high-temperature operations common to this sector—think the production of steel or cement—are limited.

Deep geothermal offers a new solution for decarbonizing industrial heat, otherwise known as process heat, by going hotter and deeper than ever before. But to understand why, it helps to consider the current state of industrial heat and decarbonization efforts.

We need industrial heat for everything from processing food to making plastics to melting steel. Today, nearly all industrial heat is powered by fossil fuels. Coal and natural gas are the largest sources, able to output the exact temperature bands at which heavy industry operates.

About 70% of industrial heat needs exceed 100°C, and almost 50% are above 400°C. Products with more complex production or refining processes, like petroleum, steel, cement, and glass, require hotter and hotter temperatures. On the other end of the spectrum, plastics need relatively low temperatures in the later stages of production. And ammonia, the backbone of fertilizers and agriculture worldwide, is created at 300-500°C.

Fossil fuels produce thermal energy, using combustion to generate power and heat. Most renewable energy sources, though, don’t directly produce heat. Wind turbines, hydropower dams, and solar panels do not use heat to generate electricity, making their applications to industrial heating much more limited. In the end, it will always be more efficient to capture heat directly versus producing it from electricity.

Solar thermal plants are one of the only renewable options for direct heat generation, but they are still intermittent like wind turbines and solar panels. This means solar thermal is not reliable all day, every day. And it is currently more difficult to store high temperature heat than it is electricity.

Geothermal and nuclear can produce power and heat 24/7, like fossil fuels, but are clean. Traditional and enhanced geothermal systems often reach temperatures around 200°C, and the most common type of nuclear reactors today operate at 200-300°C. The goal for both technologies is to reach higher temperatures and greater scale.

Geothermal energy faces the same hurdles for industrial heating as it does for electricity, namely output and location. The temperatures produced at most modern geothermal plants would not be sufficient for widespread processes like ammonia production. Plus, existing geothermal plants are limited to areas with easy access to underground hot water or steam.

Deep geothermal, however, operates at temperatures of 300-500°C, making it ideal for decarbonizing a large swath of industrial processes. And by drilling deeper into superhot rock, we can significantly expand access to high-grade geothermal heat around the world­—no preexisting water or underground steam necessary.

While deep geothermal addresses the key 300-500°C temperature band, it cannot solve all industrial heat needs by itself. To address industrial needs at higher and lower temperatures, we need a few extra systems.

For higher temperature processes, like iron smelting and steel production, electrification and hydrogen can assist. Electric arc furnaces are one way to decarbonize steel, which can be powered by deep geothermal. Hydrogen production, too, can be powered by deep geothermal to address industrial heat needs at the highest temperatures.

At lower temperatures, deep geothermal can become highly efficient. Waste heat, as in leftover heat from geothermal power production, can be captured and piped to nearby facilities that need lower-temperature industrial heat. This is called cascading and is already deployed at scale in places like Iceland. Cascading also encourages the use of co-location, building geothermal plants near industrial load centers.

To decarbonize industrial heat, as with electricity, we need bold new solutions. Deep geothermal can accelerate the transition by leveraging fossil fuel infrastructure to bring more clean heat online in record time.

Energy is everything. At Quaise, we look at the big picture to see where the world is and where it needs to go. Today, fossil fuels still dominate global energy by a long shot. A smoother transition to clean energy requires a bold new vision grounded in science, scale, and speed. Join us as we explore the future of energy and the power of deep geothermal.