Geothermal energy: the missing link in the lithium story

By Adel Muna | October 17, 2018

The Salton Sea area of Southern California is one of the world’s most active geothermal hotspots. The area is home to a naturally pressurized brine reservoir—water full of dissolved salts and minerals—where the temperature can reach 600°F in locations that go as deep as 6,000 feet. The combination of geography, geology, and chemistry make the region a natural for geothermal energy production, something that is becoming increasingly important in a world that needs clean, green power.

In simple terms, and in addition to the direct flashing method, a geothermal plant produces energy by circulating hot brine through a piping system. The pipes pass through a pool of cool water, heating it to create steam. The steam powers a turbine to produce electricity. It’s a closed-loop system, because as the brine cools, it is redirected back into the ground to start the heating process once more. By ensuring the reservoir is properly connected, production is sustained and continuous, so there’s no danger of depleting the resource.

Geothermal plants need geographies with certain characteristics. First, the ground must be permeable. The production wells must be able to produce a mass flow rate that can sustain the type of fluid absorption the process needs. Because the brine is recycled back into the reservoir after it’s been used for heat, the ground must be permeable enough to allow speedy reabsorption. Second is the geochemistry of the brine that cycles through the system. The characteristics of the salts, minerals, and chemicals it contains must be acceptable for use. If these are too toxic, it may be too expensive to make the brine acceptable for use. Third is the geothermal gradient temperature. The earth’s temperature rises the deeper one digs. Of course, moving the brine to the surface causes some cooling. The trick is finding locations where we can dig deep enough to access the heat differential the system needs to be effective.

This area of California—Imperial County—was already supporting eleven geothermal plants on the southern shore of the Salton Sea. Yet, despite the rich resources and the renewable, recyclable nature of geothermal energy, the construction of these plants had slowed due to their high cost. But now that the state has committed to one-hundred percent clean energy by 2045, there is a strong case to be made for more geothermal development.

Geothermal energy is “baseload” power. It flows night and day, winter and summer. The plants that harness it will operate for decades, so they can play an important role by complementing and leveling the cyclic-production profile of other renewable resources, notably wind and solar energy. A geothermal brine selective-extractant process is faster, significantly less water-intensive, and compact, with no need for vast evaporation ponds, which makes it ideal for the extraction of lithium.

Lithium is powering everything from cell phones to computers to transit system buses. Rechargeable lithium-ion batteries are essential to digital technology, which in turn has become essential to the way our world works. The value of lithium in all its forms—carbonate, chloride, and hydroxide—has been growing continuously, thanks to the battery industry. Demand will only continue to grow, as auto manufacturers all over the world convert to electric engines in order to “green” their businesses and comply with government regulations.

Use of geothermal energy to power an entire facility is one way in which Hatch is enabling new technologies for lithium recovery. It also demonstrates that it is possible to have the best of both worlds: green energy being used to harvest lithium, the very mineral needed to create one of the basic building blocks for storing electrical energy. As the industry advances rapidly in scale and technology, Hatch’s expertise in the lithium space, our knowledge of geothermal engineering, and our reputation for new, innovative ideas and designs that solve our clients’ toughest challenges has created a unique opportunity for us.

This is the kind of opportunity that an engineer can spend a career looking for. A new, carbon-free technology that not only reduces waste and helps combat climate change, but can be used to make a commercially viable and very much in-demand product. It’s the best kind of good news story: one that promises to keep getting better.