An EV solution to home energy storage?

The question of whether old electric vehicle batteries can be bundled together to provide home energy storage may soon be answered.


When an EV battery ages and begins to lose range, it still has plenty of life left in it. Rather than sending it straight to the recycler, you could hook it up with a bunch of other used EV batteries in a stationary storage system. Sounds like a great idea, right? The question is whether such a system is commercially viable, and Sumimoto Corporation is about to find out.

Sumimoto has just completed an energy storage system made from used EV batteries, which it claims to be the first large-scale facility of its kind in the world. The system is expected to begin operating later this month.

Well, don’t get too excited all at once. The facility is not exactly a commercial prospect, at least not yet. It is a prototype system selected by the Japan Ministry of the Environment as a model project under the category of “verification of the battery storage control to promote renewable energy”.

Sumimoto developed the facility in cooperation with Nissan, starting with the launch of a joint venture company called 4R Energy Corporation back in  2010.

Located on Yume-shima Island, Osaka, the 600 kw/400kwh system consists of 16 used EV batteries. It will charge up from the nearby Hikari-no-mori solar farm.

Over the next three years, the system will be studied for its ability to smooth out fluctuations in energy output from the solar farm, with an eye toward developing a larger, commercially viable system.

When cars eat each other

Ford Motor Company already has a similar system under its belt. Back in company installed a 500 kw solar array as part of a green makeover for its Michigan Assembly Plant, and they hooked it up to a used EV battery storage system as well as new energy storage facilities.

Like the Sumimoto system, Ford’s used battery endeavour is a demo facility. If it proves successful, a lot of those new EVs hitting the road a few years from now could be manufactured with the help of power cannibalized from old EV batteries.

So, is used EV battery energy storage commercially viable?

Maybe. Back in 2003, Sandia National Laboratory studied the issue and determined that there could be a future path to cost-effectiveness.

More recently, in 2011 Oak Ridge National Laboratory took a dim view of the matter overall, but concluded that certain applications for a used EV battery energy storage system could be profitable, one best-case scenario being the aggregation of multiple customers in a community energy storage venture:

A business case begins to emerge when applications with a low utilisation factor, like voltage support (only a few hours over the entire operating life of the system), are combined with applications that increase the utilisation factor of the system…
…Time of use energy management (peak shaving) is the most promising application for community energy storage (CES). Time of use energy management makes great sense where communities install energy storage systems controlled for peak shaving and indirect benefits to the distribution and transmission system such as upgrade deferral, and reserve supply capacity, may be realised.

The peak shaving angle could be a winner for business, if it could be integrated into an energy storage system that enables large scale utility customers to avoid high demand charges.

BMW, for one, isn’t letting Sumimoto  rest on its laurels. Last fall BMW Group announced a partnership with the company Vattenfall to develop secondary uses for EV batteries.

GM is also in on the action, with a used EV battery microgid backup system developed with the global company ABB.

Originally published on CleanTechnica. Reproduced with permission.

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