A promising new technology aims to store electricity for the power grid on the cheap. - 

Batteries can be expensive and the industrial batteries that store solar power for use when the sun goes down are especially pricey. But a promising technology, which use a non-toxic, water-based solution with salt, could make storing electricity for the grid much cheaper.

This week, Aquion Energy of Pittsburgh, who is working to mass-produce these batteries, reached a major funding milestone with an investment from Microsoft founder Bill Gates.

"These would be very big and they would improve the performance and efficiency of the whole power grid," says Aquion CEO Scott Pearson, who adds that the batteries could also be used for a residential home or on or off grid cellphone towers.

The Aqueous Hybrid Ion batteries are cheap in bulk but not that useful in miniature sizes, so don't expect them powering individual cellphones or flashlights.

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