WSJ Sept. 28, 2014 By Michael Fitzgerald
In the 1990s, Willett Kempton, a professor at the
University of Delaware, proposed in a paper that electric vehicles could
help pay for themselves by selling power back to the grid. When no one
jumped on the idea, he decided to develop the technology himself.
Now, the pilot project he spearheaded at the university in conjunction
with power-plant operator NRG Energy Inc. brings in
roughly $110 a month per electric vehicle. The
operation uses software to link a minimum of nine electric vehicles, mostly
Mini Coopers, together into a virtual power
plant on wheels that can both draw energy from the grid and discharge energy
"We're not earning enough money to get rich," says Dr.
Kempton. But "it earns money, and it earns more money than it costs to do
The vehicles—which come with chargers that allow for a
two-way flow of energy and have a custom-made circuit board added to control
the connection with the other cars and grid—essentially are being used as a
short-term ministorage facility by PJM Interconnection,
the operator of the electricity-transmission system in much of the Eastern
When more electricity is produced than is required,
PJM can discharge power to the car batteries for storage; when demand
rises, it can draw the juice back out. The utility agrees to pay for the
reserved capacity whether it uses it or not, and the controller in the
vehicle ensures that the battery isn't drained to the point that the car
can't be driven.
Scott Baker, a senior business-solutions analyst at
PJM, says the grid operator sees electric
vehicles as potential stabilizers for the system, helping to keep
frequencies smooth, especially as intermittent alternative-energy sources
like solar are added to the grid.
The Delaware project requires that a certain number of
vehicles be strung together because PJM's
system won't recognize a "power plant" with less than 100 kilowatts of
capacity, which is about what nine vehicles can provide, Dr. Kempton says.
But he envisions a day when there could be
hundreds of thousands of electric cars selling power to the grid while
plugged in at home or the office, making the vehicles more affordable