EU Energy Policy Blog

Imagine a future where intermittent renewables make up 30+% of the generation mix on a large interconnected grid. Also imagine a significant penetration of electric and/or hybrid vehicles, say 1+ million each capable of charging – and discharging – 100 kW into/out of their batteries. Would it not make perfect sense in such a case to use the large storage capacity of the batteries to store electricity when renewable resources are generating at full blast and the demand on the grid is low, and discharge some of the energy stored in the batteries when the reverse is true?

This concept, known as vehicle-to-grid, or V2G, has been around for some time among academics, visionaries and the research community. At the recent annual meeting of the American Association for the Advancement of Science (AAAS) in San Diego, CA in February it was announced that the first experimental demonstration of the idea has gone live at the University of Delaware where 3 EVs are connected to the grid when they are not in use. It turns out that the average personal car in the US is sitting idle for 22+ hours per day – hence the EVs’ batteries can be used most of the time by the grid operator.

Kenneth Huber, Technology Manager for PJM grid, which covers the mid-Atlantic region and is supporting the experiment said the 3 cars are earning $5-10 per day “by being plugged in.” According to Professor Willett Kempton, the Project Leader at the University of Delaware, the batteries act as an “electrical sponge,” absorbing excess energy when the demand on the grid is low and renewable generation is high – and discharging when the opposite is true.

While it is too early to make grand conclusions, Professor Kempton believes that investing in V2G “could pay off quickly” for an EV car owner once the “technology is commercialized.” He reckons that the extra costs of making an EV battery V2G compatible could be as little as $1,500 while the potential reward may be as high as $3,000 per annum through a “load-balancing contract” with a grid operator.

It is not hard to imagine what the longer-term implications of V2G technology may be if one assumes rapid penetration of EVs fitted with V2G capabilities – namely a sensor that allows charging and discharging in the correct direction at appropriate times and appropriate prices without blowing the transformers on the local distribution network or leaving the car owner with discharged batteries when the car is needed for transportation.

Additionally, the owner must reach an agreement with the grid operator – most likely through an aggregator and/or intermediary – to provide a reasonable revenue stream for the car owner while offering tangible storage and balancing service to the grid operator. These are formidable but not insurmountable challenges.

With projections of as many as 1 million EVs sold in the US, and potentially similar numbers in Europe and Japan, and assuming 10 kW average battery capacity, the numbers can quickly add up. In the mean time, grid operators in many parts of the world are facing increasing challenges while trying to integrate more intermittent renewable resources into the network. Gaining access to the vast electrical sponge provided by V2G technology may prove to be a welcomed blessing.

Fereidoon Shioshansi

This post is extracted from EEnergy Informer, April 2010 issue.

This entry was posted on Wednesday, March 31st, 2010 at 10:40 am and is filed under Energy Policy. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.