Your first thought about electric cars and the power grid might be that the vehicles are going gobble up more energy from grid and might cause blackouts. But the truth may be quite the opposite. Last week Nissan, makers of the fully electric Leaf, announced plans to partner with ABB to test the feasibility of creating an energy storage network from used batteries. Rather than dismantling and disposing or recycling the battery’s individual components after the vehicle’s life Nissan or another company could buy the old battery and use its remaining charge capacity to storage energy for use on the grid.

In many ways this idea is nothing new. However in the past the idea of using vehicle batteries for energy storage was based on doing so while they were still part of a vehicle. Vehicle to Grid, or V2G, technologies imagined an advanced smart grid that took advantage of millions of potential electric vehicles that would be plugged into the grid during the day.

The basics behind the idea are that typically a person would charge their electric car over night while at home, which is ideal because both electric demand and prices are lower at that time. During the day when these vehicles are then plugged in outside of your office or a shopping center, they could be called to send power back on to the grid by the smart grid systems when energy demand is typically at its peak. Vehicle owners could program how much power they need to keep so they’ll never be stuck without enough juice to get where they need to go. Vehicle owners would also be paid for the power they sell back, probably at higher rates than they bought it for the night before when charging up.

Not only could these car batteries help regulate the grid and make some money for their owners, it’s also an ideal method for storing renewable energy generation. Wind power is typically at its peak at night when demand is lower, so in effect the millions of vehicle batteries could act as storage for the wind generated electricity. And while solar power is usually producing the most power pretty close to when the grid is at its peak demand, energy storage will still be needed if solar power is going to take over a significant percentage of generation.

Nissan’s new plan is not something that will happen on a large scale any time soon, simply because electric vehicles are just rolling out, so there aren’t going to be any used batteries available for widespread commercialization of this system. However, after 20 or 30 years, when multiple generations of electric vehicles have been on the road, the amount of used batteries would become significant.

One of the difficulties with energy storage is that it is not very cost effective now. This is why using vehicle batteries (either currently in use or recycled) for energy storage is attractive. And while there remains technical hurdles to coordinate a massive V2G system that is reaching out individually to every car, the recycled batteries could be easily aggregated into one storage unit. Imagine thousands of old car batteries on site near a wind farm to soak up the excess energy, or even an old battery or two just for your home to keep you powered during a blackout or to store the power from your rooftop solar system.

Nissan claims that the batteries will still be able to reach 70% of their original charging capacity after 10 years of use. The prototype recycled battery storage system in development would hold at least 50 kWh of energy, or enough to power 30 homes for an hour.

For more information on V2G: http://www.udel.edu/V2G/