Building The World’s Largest Battery

When Tesla announced a 100 MW/129 MWh battery project in Australia, it was hailed as the world’s largest energy storage facility. Then Abu Dhabi upped the ante by announcing the largest “virtual” battery, with a capacity of 108 MW/648 MWh. Now, a partnership between Mitsubishi Hitachi Power Systems and Magnum Development is going further: all the way to 1GW in energy storage capacity.

The Advanced Clean Energy Storage, if it comes to life, will be the largest energy storage facility in the world and it will not involve lithium ion batteries. Instead, it will combine a few different energy storage technologies to ensure reliable supply of electricity, Power magazine reported last week, citing the companies. The site of the facility will be the Magnum Salt Dome in Iowa—a salt cave measuring at least one by three miles according to seismic surveying—property of Magnum Development. According to Iowa’s Governor, Gary Herbert, the project could “put Utah on the map as the epicenter of utility-scale storage for the Western U.S.”

Indeed, the ambitions of the project partners are impressive. Magnum Development focuses on compressed air energy storage and renewable hydrogen. The latter is its meeting point with Mitsubishi Hitachi Power Systems, which is working on converting renewable power into hydrogen to use as fuel for a combined-cycle power plant with a capacity of 600 MW. The compressed air and hydrogen will be complemented by flow batteries and solid oxide fuel cells to ensure the reliability of the electricity.

According to Magnum Development, the potential storage capacity of the salt cavern is virtually unlimited, and the only constraints are “market demand and technologies that create the power.” As regards the latter, the 600-MW power plant will supply most of it, and there is even the possibility of it generating enough output for the full 1-GW capacity. But how does this installed capacity translate into megawatt-hours?

ince the storage could supply power to whoever needs it around the clock, Magnum Development’s chief executive Paul Browning told Power magazine, “if you wanted to convert that to megawatt-hours, you would multiply that by 365 in 24 hours to turn 1,000 MW of capacity into how much storage there is.”

If successful, this project would serve to increase hydrogen’s prominence in the energy world. The element is tempting because of its abundance and the various ways in which it can be used as a cleaner alternative to oil and gas. Hydrogen can be used for the storage of energy through hydrolysis—the process that breaks down water into its constituent elements. The hydrogen resulting from this process is then stored in caverns or tanks until the time comes when it needs to be converted back into electricity in gas-powered plants, for instance, or in fuel cells for vehicles.

In this particular case, it’s the size of the Magnum Salt Dome that would make the project viable: hydrogen needs a lot of space for storage because it boasts one of the highest energy-per-mass levels of density but has a much lower energy-per-volume density. This has made hydrogen-based energy storage tricky since there is not an abundance of vast caverns across the world. It is also why the Advanced Clean Energy Storage project could work.

If it does, it would make a major contribution to the sharp increase in U.S. energy storage capacity that IHS Markit recently forecast. According to the research company, this will rise from 376 MW in 2018 to 712 MW this year and to almost 5 GW by 2024.

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