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Hydropower energy storage is a well known energy storage system. It is characterized by use of stores of water at a higher level than the power take off subsystem. This topic is created for NewMars members who might wish to add links, images or text about the reverse: storing water in the Earth under pressure, and harvesting energy by passing the water through turbines. The hoped-for efficiency of this system is 65%, and water consumption is likely to be less than is true for traditional above-ground systems.
The third post in this series will kick off the topic with news about a series of tests of the concept in Texas.
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This post is reserved for an index to posts that may be contributed by NewMars members.
Index:
Post #3: Kickoff article
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https://www.yahoo.com/news/articles/sci … 00388.html
Scientists Are Turning the Earth Beneath Our Feet Into a Giant Battery
Darren Orf
Fri, August 8, 2025 at 8:00 AM EDTglobal green energy, battery technology development, 3d rendering
Scientists Are Storing Extra Energy in the Earth marian - Getty Images
Here’s what you’ll learn when you read this story:
For more than a century, pumped hydropower has been the go-to technology for long-term energy storage.
Now, a Texas-based company has successfully demonstrated that its Geochemical Energy Storage (GES) system—which injects water into impermeable rock under pressure—can also store energy for up to six months with no losses.
Because GES is a closed system, it uses less water than traditional pumped hydro, and could help long-term storage proliferate throughout the U.S.
The Earth is overflowing with renewable energy. Powerful waves beat coastlines, rushing winds ripple over expansive plains, the planet’s internal heat roils beneath our feet, and the Sun’s light shines on us all. During the past several decades, scientists and engineers have drastically improved our ability to transform these energy sources into usable electrons. But that’s only the first step—the next one is finding a way to store it.
Luckily, we have options, and chief among them is the lithium-ion battery. Although these batteries have impressive round-trip efficiency—which describes how efficient the technology is at storing and then dispersing energy—lithium-ion is only useful for covering short, day-long hiccups that could impact the grid. For our renewable future to supply us with reliable energy, the grid also needs technologies that can store energy for months at a time.
To pull off this long-term storage, green energy engineers have relied on a decades-old technology known as pumped hydropower. Put simply, this process uses electric motors to pump water uphill when energy is plentiful, and when energy is needed, it flows downhill past a turbine that generates electricity. It’s a simple, elegant system, and according to CleanTechnica, it represents 95 percent of long-duration storage in the U.S. However, pumped storage isn’t perfect—it requires significant upfront costs, it can use up a lot of water, and it can be geographically limited.
The Texas-based company Quidnet takes the idea of pumped storage and flips it on its head—literally. Called “geochemical energy storage,” this process pumps water into impermeable rock within the Earth and stores it there under pressure. When released, the water flows upward, powering a turbine and releasing energy.
“The water in a GES system, minus what is lost on evaporation, is reused over and over in a closed-loop system,” Quidnet states on its website. “Due to the higher operating pressure, and thus energy density of the GES process, the volume of water cycled in the GES process is a fraction of the water cycled in a conventional pumped hydro storage facility.”
In 2019, Quidnet earned funding from the U.S. Department of Energy to develop GES technologies for commercial use. They also received $10 million in 2024 from the oil and gas company Hunt Energy Network, in part because Quidnet uses “the same supply chain and same work force” for creating GES systems, just with different rock layers. In February of 2025, the company announced that it had successfully tested and demonstrated the technology at a megawatt-hour scale, and four months later, they announced that they had stored energy for six months without any losses.
This doesn’t mean that GES’s round-trip efficiency is 100 percent (not even lithium-ion batteries can achieve such a feat). Speaking with MIT Technology Review, Quidnet CEO Joe Zhou estimated that the new system could reach a maximum efficiency of 65 percent, while the current system likely clocks in at around 50 percent. However, long-term storage is a different commercial regime than short-term storage, which relies on lithium-ion and (increasingly) iron-air batteries, so lower efficiencies are still useful.
With a wider adoption of long-term energy storage, a renewable energy grid will be more resilient in the face of various climate calamities, which are only increasing (in both frequency and severity) thanks to anthropogenic climate change. Quidnet hopes to have a GES project with a Texas utility up and running by next year.
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