A startup based in Manhattan called Urban Electric Power is taking a stab at the energy storage problem. And rather than just store energy, the company is going one step further, by manufacturing completely non-toxic batteries rather than the usual corrosive chemical-filled variety.

One big problem with renewable energy—including wind, solar and wave energy—is storing it. If we could stock up on energy when the sun is shining brightly or the wind is blowing, then we could continue to produce power at night or during windless days. Stored energy can also offset demand for energy at peak times, when utility companies have to ramp up production.

Urban Electric Power is approaching this issues by updating an old battery technology. Energy.gov explains:

Inexpensive, non-toxic and widely available, zinc has long been known to be an excellent electricity storage material because of its high energy density. Invented more than 100 years ago, the zinc anode battery is still used today. Yet, for all its benefits, zinc has one major shortcoming -- dendrite formation develops over the battery’s life, causing the battery to short after a few hundred cycles.

Basically, researchers have hit a roadblock when attempting to tap into zinc's energy-storying potential because of that material's annoying tendency to clump up. To get around this problem, Urban Electric Power designed a simple solution: just stir the zinc. Scientific American reports:

The key to preventing that degradation turns out to be flow. In the case of Urban Electric, that means little propellers attached by magnets to the bottom of the plastic container holding a series of zinc–manganese dioxide pouch cells. The fans circulate a fluid that keeps the flaws from forming, and the ions flowing in and out of the electrodes. That fluid also turns out to be cheap: water. The convection from a little bit of water flowing around the pouch cells prevents the formation of tiny fibers on the zinc electrode, known as dendrites, that kill off a typical alkaline battery. "We use very little flow," Banerjee says. "It's really just stirring."

The design is so simple that the creators use little more than homemade pasta makers, restaurant-grade stirrers and rolling pins to make the chemical materials, SciAm adds.

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