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PG&E and Tesla to Research Smart Recharging Vehicle-to-Grid Technology

Pacific Gas and Electric Company is partnering with Tesla Motors to further evolve vehicle-to-grid (V2G) technology by researching smart charging—a form of V2G designed to allow remote control charging of electric vehicles connected to the power grid.

V2G is conventionally considered as the delivery of power from a vehicle back to the power grid. However, vehicles can also provide short-term ancillary services to the grid even without delivering power back to the grid. By allowing the vehicle charging rate to be ramped up and down remotely through smart metering, a vehicle can perform a grid ancillary service called regulation. Regulation is currently performed 24/7 by power plants in order to fine tune the balance between generation and load.

Of the four power markets that are relevant to V2G—baseload power, peak power, spinning reserves and regulation—regulation is a highly competitive market opening for V2G, according to an earlier analysis by Willet Kempton and Jasna Tomić.

But electric drive vehicles, with their fast response and low capital costs, appear to be a better match for the quick-response, short-duration, electric services, such as spinning reserves and regulation. These constitute, for example, in the US, 5–10% of electric generation costs, or about US$ 10 billion/year.

—Kempton and Tomić

The project partnership will combine Tesla Motors’ electric vehicle expertise with PG&E’s electric infrastructure experience to explore the ancillary grid benefits of remote charging.

We are focusing our initial V2G implementation on smart charging. Smart charging is a form of V2G in which the vehicle does not provide power back to the grid. Instead, the vehicle charging rate is controlled remotely in order to support the operation of the grid or to best match load to the availability of intermittent renewable energy resources such as wind and solar. Tesla Motors' goal in developing V2G is to eventually provide our customers with an option that could reduce their cost of electricity for vehicle charging while supporting greater penetration of renewable energy on the grid.

—JB Straubel, Chief Technology Officer, Tesla Motors

Tesla Motors will work with PG&E to equip a demonstration all-electric Tesla Roadster with the communications technology that enables intelligent charging. PG&E will also install monitoring equipment at the auto manufacturer’s San Carlos location for testing purposes.

If this demonstration project is successful, and smart charging is deployed on a wider scale, it is expected to be interfaced with PG&E’s SmartMeter technology, which continually reads circuits and electric meter usage and has the ability to provide financial incentives to customers who voluntarily shift electricity usage away from critical peaks.

In addition to partnering with Tesla on V2G research, PG&E is working with the auto manufacturer to support the installation of Tesla Motors’ charging stations into their customers’ homes or businesses. PG&E is working with Tesla Motors to ensure proper connection in its customers’ homes within the utility’s northern and central California service territory and advising the auto manufacturer on its collaboration with utilities nationwide.

PG&E became the first utility in the nation to publicly demonstrate the possibility of electric vehicles to supply homes and business with electricity at a Silicon Valley Leadership Group event in April 2007. (Earlier post.) More recently, PG&E shared this technical expertise with Google in June 2007 to upgrade a number of company-owned Toyota Prius PHEVs to be V2G capable for a demonstration at the company’s Mountain View campus.




So in a coal power plant type of situation, how much would V2G help to reduce the impact of electric cars in greenhouse gas production?


Great idea. It would be interesting if BEV owners had the additional option of adjusting their charging based on the mix of renewable energy on the grid. Because environmental concerns are a primary motivator for people who are keen to adopt BEVs, I think they'd be quite keen to maximize the amount of renewable energy they consume and a good segment would be prepared to pay a premium for it as they do via utility bills.


Jack, where did you find data for available roof space? I've done some crude estimates, but I'd be grateful for a link to good data.
Thanks --ddw


Jack, where did you find data for available roof space? I've done some crude estimates, but I'd be grateful for a link to good data.
Thanks --ddw

I estimated it based on data in the Residential Energy Consumption Survey. I cross-checked my average square footage assumptions with estimates from the National Association of Home Builders and the numbers matched up very well.

The solar electricity potential estimate is based upon a series of assumptions, but I limit it to single-family homes (not including mobile homes) and their garages, and assume half the roof area of a standard pitched roof per home and garage. I also assume 500 square foot garages and that 70% of SF homes have unheated ones (which aren't included in the data found at the above link).

At current average solar efficiencies (12%) and average insolation (5), that space alone should be able to generate roughly 1/2 the electricity in the country (roughly 2 trillion kWh per year). Add to that the 36 million homes which aren't single family homes, the commercial and industrial buildings, and it should be more than sufficient at current efficiencies.


Jack is right on the money here.

"Not dispatchable" is the bogeyman used to keep people from pushing for more wind and solar capacity on the grid.  If the vehicle fleet can soak up all the variations from the non-dispatchable sources and the utility only has to be concerned with filling in the difference between RE generation and minimum requirements (not everyone will need a full charge) over the next 8-12 hours, entire classes of utility generators become superfluous.  If the vehicle fleet can provide reactive power, spinning reserve and regulation as well as levelling peaks, all the costly equipment doing that job today becomes surplus.  More to the point, the fuel which runs it will be free for other uses.


These empty objections about solar taking up so much space really comes into perspective when you realize that the area of US roads alone (not including things like parking lots and all the other things to support vehicles) is on the order of 50 billion square meters or 19,000 square miles -- a little less than the size of New Jersey.


I salute whoever it was at PG&E that figured out how to get their company to buy them a Tesla to play with.


I salute whoever it was at PG&E that figured out how to get their company to buy them a Tesla to play with.


I salute whoever it was at PG&E that figured out how to get their company to buy them a Tesla to play with.


By encouraging small PV/wind farms in municipalities and neighborhoods - burden is taken from the larger utils. So during an overnight charge your vehicle defaults to buying local power unless it is unavailable or too costly at the moment. In that case the "smart" logics buy the power from the main utility. The complexity is only in accessing data from various suppliers - and making purchases. Analogous to driving past three or four gas stations before selecting one to refuel at - in V2G accomplished via online transaction technology.

Jim Beyer

This really isn't V2G, it is more like smart-metering, as Hampden indicated with the A/C unit. This really isn't very newsworthy.

The notion of electric vehicles being able to store something that the grid could use is the tantalizing notion. Perhaps lots of vehicles plugged in could better stabilize intermittent resources such as wind power.

I guess having the monitor on the vehicle (instead of the charger) is a tiny new twist, but basically, there is nothing new here.

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