

Smart grid and plug-in cars — some issues

Tesla_Model_S.JPG Wikimedia Commons

Tesla Model S Sedan

Last week, in the spirit of Copenhagen, my colleague Dan Wallach and I attended the Harvard Electricity Policy Group‘s regional meeting in Austin, Texas. While a number of items were discussed, including some rather complicated legislative changes regarding the regulation of the electricity grid, we were there to learn more about potential computer security problems to be found in the SmartGrid initiative. While SmartGrid’s computer security issues should be the subject of rigorous study like any other piece of public infrastructure, there are underlying problems that are probably of greater concern to its well-being than computer hackers.

A big piece of SmartGrid is the computerized electricity meters that have the capacity report back to the electrical utility data about electricity consumption from the site of the meter. So, once there’s a SmartGrid meter on your house, there’s no need for the “meter reader” from the electric company to come out and get the reading that ultimately is used to generate your bill. The meters also permit the electrical utility to provide incentives to customers to change their consumption behavior, with the best incentive, of course, being price. The simple idea is that electricity consumed during peak hours will cost more than off-peak electricity. Move laundry or other high-electricity consumption activities to off-hours, save on the bill.

The newest major electric appliance on the horizon is the car. Lately, plug-in vehicles have attracted a great deal of interest because they are considered “green” or environmentally sustainable. GM, with its Chevy Volt electric car, is banking on the electric vehicle as an answer to the company’s prolonged slump. But as The New York Times’ test drive report on Volt indicates, there is probably a good deal of engineering work left to do before Volt is a viable prospect for the American carbuyer, especially bearing in mind its rather significant price tag, estimated at somewhere around $40,000.

Volt buyers will not, however, have to fill up at the pump anymore. Just bring the car home, pull it in the garage, plug it in and it’ll be ready to go again in a bit (which may be quantified as several hours or less). To get a cheap electric fill-up, you want to charge your electric car not when electricity prices are high or at peak, (like 6 p.m. on a July afternoon in Houston), but rather at another time when electricity is cheaper, say overnight.

That’s fine, but here’s a potential problem. During the day, electrical transformers (those big gray cans up on utility poles), heat up, but overnight as temperatures fall, they cool. Here in Houston, we all know how hot it can get during the average summer day, but if everybody on your block runs out and buys the Volt or Tesla‘s new four-door (another electric car), the transformers may not have the opportunity to cool. California, which is trying to boost electric car sales, will likely be the first to cope with the reality that quick-charge electric cars like the Tesla need a more robust energy infrastructure.

Should two or three of those customers charge vehicles simultaneously, even overnight during off-peak hours, a typical Santa Monica circuit, which serves about 10 households, could be overloaded, Ted Craver, [Southern California] Edison’s chief executive officer, told Bloomberg News in an Oct. 23, 2009, article.

So, while we are no closer to determining the exact vulnerability of the electrical grid to a highly coordinated cyber attack from, say, China, we do have a pretty good idea that if the Volt and Tesla become hot sellers, the grid will need a significant overhaul to handle the load. Whether the grid is smart or not, plug-in cars will likely require its significant upgrading, and those costs will be born by somebody, i.e. electricity consumers and taxpayers. Happy motoring.


Technology and Society