GM poised to challenge Tesla in battery storage

Greg Gardner and Chris Woodyard | Detroit Free Press and USA TODAY

DETROIT -- General Motors showed signs Tuesday that it may take on Tesla Motors in the stationary battery business with a different approach.

GM is proposing to power homes, businesses and utilities with recycled used electric car batteries from cars like its Chevrolet Volt, which has both batteries as a gas engine. Electric-car maker Tesla is going to enter the stationary power business with new, not used, units.

GM says its approach is not only more ecological because it promotes reuse, but could be more cost effective.

"Even after the battery has reached the end of its useful life in a Chevrolet Volt, up to 80% of its storage capacity remains," said Pablo Valencia, senior manager of GM's battery life cycle management. "This secondary use application extends its life, while delivering waste reduction and economic benefits on an industrial scale."

Tesla shook up the stationary storage world recently when CEO Elon Musk unveiled a unit called the Powerwall. It stores electricity generated by solar power during the day so it can be drained at night at night when there is no sunlight. Tesla, based in Palo Alto, Calif., also is creating larger units for the industrial and utility market. Tesla uses new batteries, potentially much more expensive, than the plan GM has in mind.

Giving batteries a second life bolsters the case for vehicles like the Volt, and the upcoming all-electric car, the Chevrolet Bolt.

One challenge facing GM's model, however, is that electric cars are a relatively recent phenomenon and there aren't a lot used batteries available yet.

"The supply today is very small," Valencia said. "The importance of this announcement is that we are preparing for the future. This is a preparation for that time. Typically the lifecycle of a vehicle is 10 to 12 years."

At its headquarters in downtown Detroit, GM executives showed how five Volt battery packs are already helping light offices at the company's Milford, Mich., data center. A new solar array and two wind turbines feed the Milford data center's circuit breaker panel, where the Volt batteries work in parallel to supply power to the building.

The batteries also can provide back-up power to the building for four hours in the event of an outage and stores it when it's unneeded. Excess energy is sent back to the grid that supplies the Milford campus.

The 74-kilowatt ground-mount solar array coupled with the two 2-kilowatt-hour wind turbines generate enough power to provide all of the energy needs for the office building and lighting for the adjacent parking lot. Together, these renewable sources generate approximately 100 megawatt-hours of energy annually, roughly equivalent to the energy used by 12 average households.

Gardner reported from Detroit and Woodyard from Los Angeles