The batteries that power electric vehicles like the Nissan Leaf and Chevy Volt still have as much as 80 percent of their storage capacity when they’re replaced, and figuring out what to do with them has been a headache for manufacturers.

These used batteries are no longer strong enough to run a vehicle, but unlike the cars themselves, they are difficult to take apart and recycle. Now both Nissan and General Motors have come up with a solution that not only solves, or at least delays, the recycling issue but offers businesses a way of reducing their power bills.

The New York Times reports that Nissan has just formed a partnership with Green Charge Networks to use old Leaf batteries in stationary storage systems designed to reduce the “demand charges” that businesses pay utilities.

As Green Charge explains at its website, demand charges represent as much as 50 percent of the power bill for a typical business. While residential customers pay only for the power they use, business also pay for the highest amount of power they use at any time during the billing cycle. This helps utilities defray the cost of building and maintaining the grid, which must be designed to meet peak loads.

Businesses and institutions that have battery banks to even out their use of electricity and lower their peak demands on the grid can save money, and that’s where the electric vehicle batteries come into play. Green Charge will use the Leaf batteries to build these systems, and General Motors says it will develop a similar system for used Volt batteries and sell it on its own.

Supply of batteries still inconsistent

Because sales of electric vehicles are still small, there isn’t a steady supply of the batteries available to Green Charge and others with the same idea. But the idea is promising.

General Motors is using five Volt batteries to help power a data center that’s part of its testing facility, The Times said. Photovoltaic panels and two wind turbines produce electricity at the net-zero energy facility, and the batteries can either store or deliver energy, depending on the need. The Volt batteries hold enough electricity to power the system for four hours.

The first of the Nissan-Green Charge systems, which incorporates four Leaf batteries, will be installed at a Nissan facility later this summer to reduce peak demands, the newspaper said, and the systems are apparently now ready for the commercial market.

While Leaf and GM are finding ways to repurpose old batteries, Tesla and Mercedes-Benz both have announced plans for battery storage systems for residential and business use that incorporate new lithium-ion batteries. The battery systems are built on technology developed for electric vehicles.

Lots of life left in Leaf batteries

Vic Shao, the founder and CEO of Green Charge, said Leaf batteries have a capacity of 24 kWh when new, so at 80 percent of that when they’re repurposed they would still be able to produce nearly twice the power as the larger of the two Tesla batteries, a 10 kWh model.

The number of batteries and other parts of the system can be scaled to meet the customer’s needs.

Shao said the systems would be commercially available in the 4th quarter of the year. He did not discuss pricing, but pointed out that Green Charge doesn’t sell the battery system to its commercial customers as a stand-alone package. Rather, they engineer and install the system and then split the savings with the site host. The batteries have a 10-year guaranteed life span when Green Charge acquires them from Nissan.

Because of very high demand charges for commercial customers, the systems can produce big savings. But Shao said he didn’t see the same opportunity for the residential market right now.

“I struggle with that question myself,” he said. “I believe there are certain niche residential applications available on the market today perhaps. I would say for the majority of the U.S. population, grid power is reliable and cheap and there is not really a particular need for home-based energy storage, at least economically speaking. Consumers may decide to buy home energy storage systems for other reasons other than economics.”

Green Charge now has more than 20 systems installed and running now, and close to 200 customers who are contracted in design, engineering and construction.