How we could really use geothermal energy for the energy transition

Enough heat reaches the surface of the earth’s interior to cover all of the world’s energy demand – even twice. But to make this resource usable, on the one hand, you usually have to drill deeply and, on the other hand, convert that heat into a usable form. It’s difficult and expensive, which is why geothermal systems – sometimes referred to as “forgotten renewables” – account for only about 0.3% of global electricity production.

That could change soon in the United States. The new infrastructure law recently passed by the Biden government provides $ 84 million for the US Department of Energy to build four demonstration plants in which improved geothermal systems (EGS), experimental forms of technology, are being introduced. tested.

The funds are only a tiny fraction of the $ 62 billion available to the Energy Ministry under the Infrastructure Act, which also provides funds for the construction of new long-distance transmission lines, strengthening of the battery supply chain and maintenance of nuclear power plants. However, geothermal researchers believe that even these limited resources could make the transition from EGS to commercial use much easier. “Geothermal energy is really ripe for prime time,” says Tim Latimer, founder and CEO of start-up EGS Fervo.

The attraction of geothermal energy lies in its persistence: while the electricity production of wind and solar systems fluctuates with the weather and the time of day, geothermal energy is always in operation and provides a source of energy. stable electricity.

“It really is the only renewable base power source,” says Jody Robins, geothermal engineer at the National Renewable Energy Laboratory. Only nuclear energy – carbon-free but non-renewable – could play a similar role, even if costs, the problem of storage and public perception limit its use.

Modern geothermal power plants have been in operation in the United States since the 1970s. In these systems, hot water or steam is typically pumped from the subsoil to the surface to drive a turbine and produce electricity. ‘electricity. The water is then pumped downward to maintain pressure in the basement so the process can continue.

The best geothermal locations have certain characteristics: geothermal energy, permeable rock, and water – all in close proximity to each other and not too far from the surface. However, the most accessible locations – in the United States, they are mainly concentrated in the west – have already been developed. While researchers believe there are many more potential locations to be found, it is difficult to determine where they are. And in most of the eastern parts of the United States and many other places around the world, underground rock is not made the same way that conventional systems work – or there is a lack of water.

Some researchers and start-ups are therefore trying to use geothermal energy in new places. With EGS, they want to change the subsoil by pumping liquid through impermeable rock and opening the necessary paths. This creates a space in which the water can move freely and heat up, creating the steam needed to generate energy. This is not entirely without problems: the process can trigger earthquakes, as the first projects in South Korea and Switzerland have shown. However, EGS is similar to hydraulic fracturing, which is prevalent in the United States – and the risks should be manageable in most cases, says Robins. With this approach, geothermal energy could be extended to places that lack the groundwater or rock types required for traditional installations.

However, it will not be easy to access these resources. Commercial wells typically don’t go much deeper than seven kilometers – often even less for cost reasons – and many areas that could benefit from geothermal energy are not warm enough at that depth to reach the required 150 degrees Celsius. for economical electricity production. . In order to achieve adequate temperatures, it may be necessary to go further, requiring new techniques capable of withstanding high heat and pressure.

Fervo has addressed a few issues on its own projects, including a company announced earlier this year with Google to install geothermal capacity near the company’s data centers in Nevada. Fervo recently joined a US Department of Energy project in central Utah called FORGE (Frontier Observatory for Geothermal Energy Research).

As part of FORGE, scientific researchers and industry colleagues are trying to come up with the best ideas for using EGS, including drilling and servicing reservoirs. The site was chosen because its geology is fairly representative of where other EGS facilities could be built in the United States, says Lauren Boyd, EGS program manager in the department’s office of geothermal technologies.

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With the new funds from the Infrastructure Law, the authority will finance four more demonstration plants. This will expand researchers’ knowledge of building EGS systems, as they can work in different locations and with different types of rock. At least one system will be built in the eastern United States, where geothermal energy has so far been less common.

But technological hurdles aren’t the only ones slowing the progress of geothermal energy, says Susan Hamm, director of the Geothermal Technologies Office at the US Department of Energy. The construction of a geothermal system can take up to ten years due to the large number of permits required. By simplifying the bureaucracy, this time could be halved and the planned geothermal capacity doubled by 2050.

Funding geothermal projects can also be a challenge. They have a higher capital cost than solar or wind projects: $ 3,000 to $ 6,000 per kilowatt, compared to $ 1,700 to $ 2,100 per kilowatt for wind and solar systems. (However, a geothermal system produces two to four times more electricity than a wind or solar system of the same capacity.)

In some regions, geothermal energy now enjoys tax breaks similar to those of other forms of renewable energy. However, given that, as mentioned, it can take almost a decade to begin construction on a project, developers cannot rely on the tax breaks to stay in place until the facility is up and running. .

With a combination of new policy frameworks and technological advances, geothermal power generation in the United States could reach up to 60 gigawatts by 2050, according to a report from the United States Department of Energy in 2019. That would mean that geothermal energy would represent nearly 9%. of all electricity production in the United States, up from 0.4% today.


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