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Summary:

Should energy storage be as clean as the renewable energy that it will be paired with?

USC professor Sri Narayan working on an organic flow battery. Image courtesy of USC Photo / Gus Ruelas.
photo: Image courtesy of USC Photo / Gus Ruelas.

Most batteries — whether they’re embedded in your iPhone or they’re plugged into the power grid somewhere — use some kind of metal to create the chemical reaction that stores the energy. In laptops and Teslas, that metal is lithium; in traditional cars it’s lead. But researchers at University of Southern California are developing an all-organic, water-based battery that can be entirely synthesized (not using materials mined from the earth) and uses no metals or toxic chemicals.

USC chemistry professor Sri Narayan told me he thinks that in the future, when batteries are scaled up to the point where they’re commonly used on the power grid at large sizes, then using metals and toxic chemicals in them will be a big problem. He thinks the notion of “clean storage” — batteries made using more sustainable methods — will be important down the road.

USC research on an organic flow battery.

USC research on an organic flow battery.

Batteries that use naturally occurring water and organic molecules could also be less expensive than comparable batteries that use rare or expensive metals. As the demand for grid batteries grows, metals under any type of supply constraint could increase in price.

Narayan’s battery uses water and organic compounds called quinones (oxidized organic compounds) for its electroactive part. Quinones are naturally occurring, energy-storing compounds found in plants, animals and bacteria and are used in photosynthesis and cellular respiration. The battery specifically uses an adapted version of benzoquinone that can be dissolved in water.

The USC battery isn’t designed like the closed ones used in your phone and laptop. It’s a redox flow battery. Fow batteries store energy like lithium ion batteries but have their electrolyte (the substance that acts as the medium for the charging and discharging of the battery) separated out of the battery cell in liquid-filled tanks. Flow batteries are used for stationary applications like the power grid — you won’t find them in moving cars or mobile gadgets.

USC Post Doctorate Bo Yang working on the organic flow battery. Image courtesy of USC Photo / Gus Ruelas.

USC Post Doctorate Bo Yang working on the organic flow battery. Image courtesy of USC Photo / Gus Ruelas.

While it might sound like an awkward set-up, the benefit of a flow battery is that it can be cheaper than traditional metal-based closed batteries, it can be more flexible (you can add more tanks and electroactive material to that type of open system), it can last many more years (the electrolyte doesn’t degrade as fast) and it can provide a longer burst of sustained power. Dozens of companies and researchers are trying to innovate around flow batteries, from startup EnerVault to startup Primus Power, to lab work like that at Harvard.

But the USC group is one of the only projects using organic compounds and no metal. Many redox-flow batteries use vanadium. EnerVault’s uses iron-chromium.

Narayan says the goal is for his battery to cost $100 per kilowatt hour and last for 15 years. Lead acid batteries cost about that today, but they last only about a year.

The battery is still in the lab phase, and USC is funding its research in part with a grant, awarded last year, from the Department of Energy’s early-stage high-risk ARPA-E. program. If the battery moves through the lab stage with flying colors and proves to be promising for commercialization, Narayan says USC might work with a company in Colorado to produce a commercial battery.

  1. This is fascinating stuff — do you know if this can use salt water or must the water be potable/filtered/sterilized?

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  2. Very interesting – however, for accuracy’s sake, my solar system’s GSM batteries will last at least ten, but mostlikely twelve years. I have sealed lead acid batteries which have been used as portable power tool batteries for 8 to 10 years. I have been living on off-grid power for 29 years, and I still use the first solar panel I bought with the house. It still puts out 19V in full sunlight. The lead acid batteries for this setup, 6x 2V cells, were in use for about 14years before they became unserviceable.

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  3. Like most battery tech advances and discoveries, this is exciting stuff but unfortunately not many hit the ground running – ie: commercially viable. It is only a matter of time before we see a few revolutionary storage breakthroughs – I can’t wait. I work in renewables at the ‘coal-face’ (bad pun!) we install off-grid systems all the time and batteries are always the key discussion point – you can go cheap and short life or expensive with longer life. Generally you are looking at around $40-$80/month replacement cost for lead acid. We often recommend Nickel Iron batteries but these also have their limitations – there is a battery for every application – just not the perfect one yet!

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