

To dissuade the owners of electric cars from recharging their vehicles at peak times, and encourage them to do so in the wee, small hours of the morning instead, some electricity companies are introducing off-peak pricing for electric cars. Off-peak pricing is a common way of persuading people to run appliances such as washing machines at times of low demand. It is, though, a rigid arrangement that cannot respond to fluctuations in the requirement for power. Far better, reckon Alex Rogers and his colleagues at Southampton University, in England, for car owners to be represented in their interactions with the local power supplier by agents that can negotiate a deal on their behalf. These agents would bargain with one another, and with the power company, to charge the cars in an area in the most efficient way. The twist is that the agents Dr Rogers proposes to recruit for the task are not people, but computer programs.



Dr Roger's agents use sophisticated sealed-bid auctions to purchase the units they require, and the system that runs the operation employs algorithms based on game theory, to force the agents to collaborate in ways that result in both the best outcome for themselves (the lowest price consistent with a car being fully charged at the appointed time) and for the power company (the smoothest flow of current through the system). 

Eventually, the programs may act as sales agents, as well as buying ones. The batteries of cars that were not being driven might, according to some visionaries, act as reservoirs which a power company could draw upon to smooth out peaks and troughs in demand. A project being rolled out in Japan by Nissan, the maker of an electric car called the Leaf, could be the first step towards that. It employs a Leaf's battery to provide the car-owner's home with power. Nissan's idea is that a fully charged Leaf could run the average Japanese household for two days, which it thinks would help when power lines are knocked out by earthquakes or typhoons, both of which are common in Japan. If this idea works, it is but a short step to pumping power into the wider grid in exchange for a rebate on the household electricity bill. One day, then, Dr Rogers's software agents could be flogging units of electricity as well as buying them.