Geothermal myth #2: “Geothermal is geographically constrained”

April 4, 2023

In this five-part “Geothermal Mythbusters” series, Fervo will debunk common misconceptions associated with the geothermal industry.

When you think of geothermal energy, you might picture an Icelandic hot spring, emanating clouds of steam, or the iconic Old Faithful, spewing water into the air. Though these naturally occurring systems are examples of geothermal, they do not capture the resource’s full potential.

Advancements in drilling technology and subsurface analytics can broaden the reach of geothermal far beyond these goldilocks locations. With drilling and completions equipment already available today, Fervo has developed the ability to access over 250,000 MW of geothermal power located less than 5 km below ground, benefiting communities across the United States.

How Traditional Geothermal Works

Using traditional methods, producing geothermal power requires a very specific set of reservoir conditions including heat, permeability, and fluid. Heat from the core of the earth acts as an energy source, elevating temperatures beneath the earth’s surface. Large fissures in subsurface rock provide paths for water to travel and conduct heat. As water flows through these cracks, it heats up, ultimately producing steam that can power a turbine to generate electricity. This type of geothermal is referred to as hydrothermal geothermal energy.

This traditional approach has significant geographic limitations. The U.S. Geological Survey (USGS) estimates that identified hydrothermal resources can provide roughly 9,000 MW of electric power. These sites are located in a select few locations across the Western U.S.

While the USGS projects that innovations in geothermal exploration could unlock an additional 30,000 MW of undiscovered hydrothermal resources, the reservoirs that are well-suited to this type of development are still somewhat geographically constrained.

Luckily, new approaches to geothermal energy development require much less specific subsurface conditions, breaking down the traditional geographic constraint.

How Fervo Expands the Geothermal Landscape

Fervo leverages horizontal drilling, distributed fiber optic sensing, and multi-zonal completion techniques to introduce fluid and increase permeability in the subsurface. By injecting water underground and creating pathways in the rock for that water to flow, Fervo no longer has to worry about finding perfect, naturally occurring hydrothermal resources.

Instead, Fervo can focus on analyzing the temperature profiles of different prospects. Geothermal electricity generation is typically economic at temperatures greater than or equal to 150C. With existing drilling capabilities, Fervo seeks to tap into these resources less than 4 km  beneath the surface, which offer nearly 300,000 MW in capacity.

Looking for land with subsurface temperatures greater than 150C at less than 4 km is significantly easier than looking for land with the same temperature requirements and ample permeability. When temperature is the sole constraint, geothermal becomes a much more scalable resource.

Next-generation geothermal technology could deliver over 250,000 MW of 24/7 carbon-free power to the grid, more than 8 times the amount of estimated capacity associated with undiscovered hydrothermal resources and more than 25 times the amount of capacity provided by identified hydrothermal reservoirs. With strong transmission, this power could support communities across the country, far beyond the western U.S.

Thanks to advancements from Fervo, geothermal is no longer the niche, geographically limited energy source it once was.

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