Iron, salt and water could change power grid

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Capital News Service

LANSING – Batteries come in different sizes: AA, AAA, a 27 billion gallon reservoir of Lake Michigan water.

And perhaps someday: a warehouse of iron, salt and water.

Those are the basic ingredients for iron-flow batteries, a technology that could help pave the way for the Great Lakes region’s green energy future.

And the future must be green. Otherwise, the effects of uncontrolled climate change could cause more frequent severe weather events, human displacement due to droughts and high sea levels, according to a United Nations report.

Energy storage is a priority for many states, including Michigan, Wisconsin and Pennsylvania. As alternative energy prices dropped, demand for energy storage increased, according to the U.S. Energy Information Administration.

The Institute for Energy Innovation produced an energy storage roadmap for the Michigan Department of Environment, Great Lakes and Energy in March. It set a minimum storage requirement of 4,000 megawatts by 2040.

In April, Wisconsin Gov. Tony Evers released his state’s Clean Energy Plan, which highlighted energy storage as a key component of decarbonization.

Pennsylvania formed an Energy Storage Consortium in 2021. It served as a forum for discussing energy storage goals and strategies, said Geoff Bristow, the regional energy program manager for the state Department of Environmental Protection.

“What we need to do is get a better common understanding just what the opportunities and benefits are to various storage approaches,” Bristow said.

One benefit is filling gaps between renewable energy production and energy use, Bristow said.

Peak energy production doesn’t necessarily coincide with peak energy use when it comes to solar and wind energy. So storing otherwise wasted energy is essential for cutting fossil fuels out of the energy equation, according to the International Energy Agency.

Large-scale storage is nothing new. The Ludington Pumped Storage Plant on Lake Michigan was built in the 1970s and can store nearly 2,000 megawatts.

One megawatt provides enough electricity to power central air conditioning for about 250 homes, according to Environment, Great Lakes and Energy.

These plants pump water up to a reservoir during peak hours of energy production, when electricity is cheaper. Then the water flows down during hours of peak consumption, when electricity is expensive.

Creation and management of the Ludington plant has been a good lesson for Michigan in terms of grid scale energy storage, and increasing energy storage is another tool in the toolbelt in the transition to green energy, said state Public Service Commissioner Katherine Peretick.

Pumped-storage hydropower is efficient and accounts for 90% of the world’s energy storage capacity, according to the International Energy Agency.

But pumped-storage hydropower plants are hard to site. They take a lot of space and need a lot of elevation, said Robert Savinell, an electrochemical researcher at Case Western Reserve University.

Those siting restrictions often make it hard to build near a large city where energy is most needed, Savinell said.

Lithium-ion batteries dominate the rest of grid level energy storage, but they are expensive to scale for long-term storage, Savinell said.

Iron-flow batteries excel at storing energy in the long term and are flexible in where they can be built, Savinell said.

They use tanks of iron and salt dissolved in water to create an electrolyte solution, the liquid responsible for storing and creating energy.

Because those elements are nontoxic and nonflammable, iron-flow batteries are much safer than lithium-ion batteries and much cheaper to scale, Savinell said.

The Michigan roadmap from the Institute for Energy Innovation established a minimum energy storage requirement of 4,000 more megawatts by 2040.

Iron-flow batteries capable of storing and delivering energy at a grid level are still in development, ESS Inc. is one of the only U.S. companies working to develop them commercially, Savinell said.

While iron-flow batteries are good at storing energy for a long time, they don’t store as much as lithium-ion batteries. That means they need a lot more electrolyte solution to store energy at grid level, Savinell said.

Without increased long-term energy storage it will be impossible to fully rely on renewable energy, Savinell said.

“Electrical energy storage is going to enable electrical energy to be used when and where it’s needed, more so then just when and where it’s generated.” Bristow said.

Jake Christie reports for Great Lakes Echo.

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