Breakthrough Could Allow The US To Meet 450% Of Its Energy Demand From A Single Carbon-Free Source
Breakthrough Could Allow The US To Meet 450% Of Its Energy Demand From A Single Carbon-Free Source
Widespread enhanced geothermal power is inching closer to reality.
You might think that geothermal power is limited to highly volcanic locations like Ice Land, but you’d be mistaken. This super clean elemental energy is widespread. Take the US; it has an estimated 15 billion GWh of thermal power availability, and 5,157 GW of accessible geothermal power just sat there waiting to be used. That is the equivalent of 450% of the current US energy consumption. If the US can tap into this energy source, it could revolutionise its energy infrastructure and even the economy by becoming a clean energy exporter. But there is a problem: harnessing this non-volcanic geothermal energy is incredibly challenging and expensive. But all that might be about to change thanks to Fervo energy.
So why is it hard to tap into these geothermal reserves? You might think they are too deep to be commercially used. While that is true for many potential geothermal sites, that isn’t what’s happening here. That estimate of 5,157 GW of accessible geothermal power is for Enhanced Geothermal Systems (EGS) (also known as Hot Dry Rock), which is at the same depth as normal geothermal power, but requires different technology to extract energy. Let me explain.
Typical geothermal sites need highly permeable rocks to function. They work by drilling two boreholes down to the geothermal site. Water is injected into one borehole, and at the bottom, it permeates through the super-hot porous rock. This dramatically increases the surface area between the rock and water, which in turn speeds up the heating of the water, turning it to steam quicker. This builds up pressure, forcing steam up the other borehole, and once at the surface, this steam drives a turbine to make power before it is cooled and condensed back into water and reinjected.
These porous rocks tend to occur near volcanic sites. But geothermal reserves away from volcanic sites tend to have non-porous rocks. This can dramatically slow the rate at which water is heated and turned to steam, rendering geothermal power useless. As such, Enhanced Geothermal Systems were invented. These use multiple wells/boreholes and hydraulic fracturing (where water pressure is used to fracture the rock at the base of the borehole to create permeability) of the subsurface rocks to increase the heating rate and enable us to tap into these untouched geothermal reserves.
But, as of yet, no one has commercialised an EGS capable of supplying an energy grid. They either struggle to create stable fractures, or the costs of drilling and creation are simply too much. But all of that is about to change, thanks to Fervo.
Fervo is a Google-backed geothermal energy startup looking to be the first to commercially tap into EGS power. They have developed ways to use already existing drilling and borehole monitoring technology from the oil and gas industry to create stable, low-cost EGS power stations. They recently completed a 30-day trial of this technology with their prototype power station with astonishing results.
Their geothermal power station has a bore depth of only 7,700 ft (1.4 miles) to the geothermal site, where rock temperatures reached 375 degrees Fahrenheit (190 degrees Celsius). But unlike other EGSs, they then drilled 3,250 ft (0.6 miles) horizontally. This means that when they hydraulically fracture the rock, more fracturing happens, giving greater surface area, faster heating, and more energy extraction. This also means it doesn’t need to create deep fractures to generate a large enough reservoir, which increases the stability of the well. All of this means they can extract more heat, and therefore energy, from a borehole compared to other EGSs, which means they need to drill fewer boreholes. As this drilling is the most expensive part of EGS, this dramatically lowers its price of energy, making commercialisation possible.
During the 30-day test, Fervo’s prototype single-well power station performed way better than expected. It produced a record-breaking 3.5 MW of power, enough to power 2,500 US homes!
This puts Fervo at the forefront of geothermal energy. It also means they are able to get significant governmental support to commercialise and scale this technology. You see, the US government knows it has one of the world’s largest geothermal energy reserves and that developments in EGS could secure all the low-carbon energy they would ever want. So the Biden Administration launched the Enhanced Geothermal Shot, a department-wide effort to dramatically reduce the cost of EGS by 90%, to $45 per megawatt hour by 2035, putting the cost of EGS on par with other renewables like solar and wind. This support is likely why Fervo has some bold targets. It plans to construct a 400 MW commercial EGS power plant and have it online and supplying the energy grid by 2028! If this goes well, then the sky is the limit for Fervo. As it uses already-developed technology that is widely used in the fossil fuel industry, it can rapidly expand because the materials, tools and trained personnel it needs are plentiful. So don’t be too surprised if Fervo revolutionises the US energy industry over the coming decades.
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Sources: Fervo, Harvard, Science Direct, Earth ArXiv, Clean Air Task Force, FAS, Energy.gov, CNBC, The Independent