Adventures In Energy Storage: Redox Flow & Gravity Technology News

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Energy storage is much on the mind of people in the utility industry these days. A decade ago, storing electricity was prohibitively expensive. Of course, a decade ago, solar panels were also expensive, but the cost of both has plummeted in the past 10 years. Tesla is leading the way when it comes to lithium-ion battery storage, but other technologies are gaining ground.

Redox Flow Technology

Schmid Group Saudi JV
Image credit: Schmid Group

Flow batteries operate by having two electrically charged fluids — one with a negative charge and the other with a positive charge — stored in tanks that are separated by a membrane that allows electrons to pass from one to the other. Just last week, Form Energy, a startup supported by Bill Gates, among others, signed a deal with Great River Energy for a flow battery capable of providing up to 150 hours of energy storage. The technology behind the Form Energy battery is a closely guarded secret but it appears to rely on a solution of water and sulfur, so it is a form of flow battery.

Now PV Magazine reports that German company Schmid Group and Nusaned Investment have joined forces to develop a 3 GWh vanadium redox flow battery production facility in Saudi Arabia. Nusaned is a subsidiary of Saudi Aramco. The consortium is planning to begin manufacturing activities at the new facility in 2021. The products will be sold under the Everflow brand to utility companies, telecom towers, mining sites, remote cities, and offgrid locations.

“The new JV will aim to establish a leadership position in the rapidly developing energy storage market and both companies are fully committed to realizing our joint vision for the project,” says Schmid CEO, Christian Schmid.

Gravitricity Is Exactly What Is Sounds Like

Gravitiricity energy storage
Image credit: Gravitricity

Gravity storage is not new and is similar to pumped hydro storage — use excess electricity to lift heavy weights when demand is low, then allow the weights to turn generators as they fall back to Earth when demand is high. Scottish startup Gravitricity has developed a gravity energy storage system it says is perfect for storing solar and wind power.

It is planning a 250 kW prototype facility in the port city of Leith. The pilot system will use two 25-ton weights suspended by steel cables. “This two-month test program will confirm our modeling and give us valuable data for our first full-scale, 4 MW project, which will commence in 2021,” Gravitricity lead engineer Miles Franklin tells PV Magazine. The demonstration system will cost £1 million.

When completed this December, the 250 kW prototype will be connected to the port’s power network and have its speed of response for grid stabilization assessed. “The demonstrator at the Port of Leith will allow the technology to be trialed on a much smaller scale, utilizing an above ground structure,” the company said.

Gravitricity said the mass used can range from 500 to 5,000 tons and the electricity discharged could power 30,000 nearby homes for two hours. It says abandoned coal mines are ideal locations for its systems but they can be installed in urban areas as well, provided the necessary tunnels into the Earth can be made deep enough.

The company claims sophisticated winches and a control system can lower the mass very quickly, making it flexible enough to stabilize electricity networks at 50Hz and ensuring the installation can respond to full power demand in less than a second. “Our technology has the fast response time of lithium-ion batteries,” the company said. (Actually, batteries can often respond in milliseconds.) It also says the system offers a 25-year service life without loss of performance or cyclical degradation and can be sited anywhere, including in city centers.

Both flow batteries and gravity storage are technically feasible. The question is whether they can compete with the ever falling prices and ultra-fast response times of lithium ion batteries. Those questions remain unanswered for the moment.

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Steve Hanley

Steve writes about the interface between technology and sustainability from his home in Florida or anywhere else The Force may lead him. He is proud to be "woke" and doesn't really give a damn why the glass broke. He believes passionately in what Socrates said 3000 years ago: "The secret to change is to focus all of your energy not on fighting the old but on building the new." You can follow him on Substack and LinkedIn but not on Fakebook or any social media platforms controlled by narcissistic yahoos.

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