A recent article in Forbes, “Simon Says ‘Charge Your EV at the Mall,'” highlights the combined use of solar panels, battery storage, and electric vehicle charging equipment in an “integrated charging station” at a mall in Carmel, Indiana. It may play well as a publicity-attracting gimmick for this “‘lifestyle center’ shopping destination,” but it doesn’t make any sense as the basis for wider public infrastructure.
Electric cars generally have a lot of flexibility as to when they charge, as my graduate student Mahdi Kefayati has demonstrated in recent research. He developed a policy, “average rate charging,” which takes advantage of this flexibility to fill in the “valleys” of low electric loads using vehicle charging and to better match the times when Texas wind is blowing most strongly. His policy, if implemented, would help to make better use of our electric grid infrastructure by avoiding charging at times of peak loads.
In contrast, choosing to charge cars at the mall during the day, and particularly choosing to charge them in the middle of the afternoon, will make the time of charging coincide with when electric demand is likely to be at a peak in summer. This will mean either increased load on the electric grid or expensive solutions such as dedicated solar panels and battery storage, as proposed for the mall.
This mall initiative highlights the dangers of rushing to high-profile initiatives that don’t leverage the particular value of specific energy-producing techniques. For example, solar panels tend to generate the most power around the time of peak electricity demand. An investment in solar panels typically means an investment in power that is being produced for demands that are hard to re-schedule away from the peak. It just doesn’t make sense to invest in solar power in order to store its energy for off-peak use. Doing so takes a high value resource and uses it for a lower value application.
While the private decisions of a mall to spend money on an advertising gimmick is up to the mall investors, we should be particularly careful to avoid spending public money on such poor investments in a green future.
It was an honor to deliver a keynote speech at the recent University of Texas Center for Transportation Research Symposium. The theme: “Energy is the Key.” In my talk, “Harnessing Electric Vehicle Demand Flexibility” (joint work with graduate student Mahdi Kefayati), I offered a slightly different take: both energy and power are the keys.
