Stakeholders Fuel EV Charging Parameters

By Published On: October 24, 2013

The number and type of electric vehicles expected to charge from—and feed into—the grid is another concern for the electric industry, which is grappling with adapting to and anticipating changes forced upon it from evolving technologies and a resource mix. The California grid operator and some electric vehicle manufacturers worry about the lack of state policy setting a framework to accommodate the anticipated growth of these cars. A specific concern is the lack of variable pricing that motivates electric vehicle owners to charge their vehicles during times of surplus energy, particular when solar and/or wind resources are peaking and energy demand is low. For example, off-peak charging could cost 3 cents/kWh while on peak at a rate steep enough to grab electric vehicle owners’ attention. “It is the Wild West” for electric vehicles, particularly in terms of where and when to charge, JB Straubel, Tesla Motors cofounder and chief technical officer, said Oct. 24. As with nearly all energy issues, the matter is complicated by the various needs, demands and capabilities of the state wide transmission contrasted with local distribution ones. Steve Berberich, California Independent System Operator president and chief executive officer, called for an expansion of technology that allows car owners to program vehicle charge times to real- time off peak periods. That should exclude—or at least limit—some nighttime charging because transformers need to cool, he told Current. Tesla vehicles have on board technology allowing the driver to set charging times, as well as the amount of amps. Unlike two-way data flows Berberich envisions, the charging does not yet respond to grid conditions. Berberich estimated that the transmission system could accommodate about 1 million vehicles in California, representing roughly 3,000 MW. The number varies because it depends on the type of vehicle. Most electric vehicles, excluding Tesla, use the equivalent of about two air conditions—about 6.6kwh. Teslas use far more. For private and public utilities it is a different matter, specifically how increases in charging impact the lower voltage distribution system. Fong Wan, Pacific Gas & Electric senior vice president of procurement, said the issue was more the type of the vehicle than number at this point. He noted the amount of energy the Tesla consumers was a concern. Wan called for wide use of so-called “smart chargers” that interface with utility data. Vehicles that plug into 110 sockets are a non-issue because of the minimal impact to the utility wires, he added. The Sacramento Municipal Utility District is confident that its advanced energy forecasts, which include estimates of the number of electric vehicle purchases and their location, allow it to accommodate rising numbers of vehicles feed from and into its distribution lines. The muni’s 10-year energy trend analysis is closely tracking vehicle growth, said Elisabeth Brinton, SMUD’s chief communication officer.

Share this story

Not a member yet?

Subscribe Now