Duke Energy and ITOCHU Corp. announced a partnership today through which they will evaluate and test new uses for old electric vehicle (EV) batteries. Once they are too spent for life on-the-road, EV batteries could store power and deliver a charge elsewhere, the companies reason.

EV batteries falling below 80 percent of their original capacity when fully charged will be candidates for replacement and reuse. Duke and Itochu promised to begin their project by testing Ener1 lithium-ion batteries extracted from a fleet of 80 EVs in a Duke Energy facility in Indianapolis.

The automaker GM embarked on a similar initiative with The ABB Group in September, specifically looking for ways to use spent Chevy Volt batteries in the smart grid. One vision of reuse for EV batteries proposed by GM would see them storing power from renewable sources in EV charging stations, which are used to charge plug-in vehicles.

Other ideas (as reported by MSNBC.com and Gas2.org) include using the weakened EV batteries to keep cell phone towers up and running during blackouts, or to stabilize the grid by storing power generated either during off-peak hours or from intermittently available renewable sources, like wind or solar, finally dispensing it during peak demand hours.

EV skeptics believe that production and recycling of EV batteries— at least until battery design and reycling related technology improves— might make electric vehicles more harmful to the environment than the highest-efficiency diesel models. That’s especially if a majority of electricity used to charge EVs comes from non-renewable sources, like coal.

Giving batteries a new life beyond the vehicle, and using them to shift electricity production to renewables as much as possible would quiet many of these worries. At the same time, companies like GM, Duke, ABB Group and Itochu hope that increasing the total lifetime value of EV batteries would ultimately reduce the cost of producing them as well.