Flow battery on course to provide large-scale renewable energy storage

Date: Aug 9, 2018

By developing a new organic compound, scientists at Harvard have created a flow battery that could one day help power utilities make more use of wind and solar energy.

Utilities that operate the grids that power cities need safe and cheap energy storage to help them use less fossil fuels and cut emissions.

Methuselah flow battery in lab









The researchers tested the new compound in a laboratory-scale flow battery. Image: Eliza Grinnell / Harvard.

With fossil fuels, they can match rising and falling demand by simply burning more or less fuel. But renewables like wind and solar make energy intermittently.

The technology for capturing wind and solar energy is now quite advanced and the price is falling. The industry is now waiting for storage solutions to catch up.

Search for cheaper material

Lithium ion batteries go some way to solving the problem, but they are only suitable for discharging small to moderate amounts of energy, such as for powering cellphones and homes.

Scientists have already shown that flow batteries are safer and cheaper than lithium ion batteries for discharging a lot of electricity.

Unlike a conventional battery, a flow battery stores energy in charged electrolytes that are dissolved in liquids that are held in external tanks.

It has been described as “both a fuel cell and a battery.”

But many designs use quite costly materials such as vanadium in the electrolyte. A search for an alternative material has led to organic molecules called quinones.

Longer-lasting, better performing energy-storing molecule

However, while flow batteries based on quinones are cheaper to make, they don’t last as long as those that use vanadium.

Now, researchers from Harvard University and the Harvard School of Engineering and Applied Sciences in Cambridge, MA, have created and tested a new organic molecule that lasts longer and does the work better than any predecessor.

They believe that a flow battery using the molecule – which they call the “Methuselah quinone” to mark its longevity – could charge and discharge energy tens of thousands of times over several years without degrading.

The team describes the work that went into the creation and testing of the Methuselah quinone in a paper that is published in the journal Joule.

“We designed,” says study co-leader Roy G. Gordon, who holds professorships in chemistry and materials science at both Harvard establishments, “and built a new organic compound that can store electrical energy and also has a very long life before it decomposes.”

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