One of the things that are catching up right now is the installation of EV charging stations close to home. This is so that people would have the convenience of “fueling up” in the comfort of their homes and not have to stay long in a charging station. But who would have thought that instead of drawing power from the grid, an EV would instead be selling power?
Well, it turns out that a professor at the University of Delaware, Willett Kempton, had thought of it. Around two decades ago, in fact. With the help of power plant operator, NRG Energy Inc., he put up a pilot fleet of vehicles, most of which were Mini Coopers like the ones above. The cars were configured so that they could act as battery banks on wheels, providing short term power storage for PJM Interconnection, a major grid operator in the Eastern US.
When there is a surplus of power, PJM charges the car batteries for storage. When there’s a big demand for power, on the other hand, the grid can draw back the power. The utility pays a fixed fee for reserve capacity, whether it is used or not, like other ancillary services. The EV is equipped with a controller to ensure that the car still has enough juice for the trip to the grocery and back.
The idea makes sense. After all, EVs need batteries to move around and electric utilities use energy storage, such as battery banks, for grid stability. Unfortunately, things have to change for this to make the jump from the pilot to the commercial stage.
For one, PJM can only dispatch the power in the fleet when they are strung together, its system only recognizes power plants with 100 kW of capacity and up. The control systems of other utilities will have their own minimum dispatch requirements.
There are also car issues to address. One is the fact that most EVs don’t come with two-way chargers, like those that the pilot is using. If these were integrated into new cars, they could add $200 to the price. Also, the control boards that the pilot fleet are using are not yet commercially available. But things are about to change, it seems, because two big car makers and an auto parts maker have already expressed interest in the technology.
Finally, laws and regulations have to be changed before we can use cars for power storage. In the US, the Federal Energy Regulatory Commission already drafted rules regarding the use of alternative storage technologies, such as batteries on cars. The Delaware pilot only got the green light after Dr. Kempton convinced the state utility commission to make the regulations and after the Delaware state legislature made a law to allow cars to sell power back to the grid.
Just the same, the idea makes some economic sense, hopefully enough to pay back for the EV cost someday. The cars in the pilot fleet rake in around $110 a month each from the fixed fee that PJM Interconnection. It may not be able to fully cover the monthly lease yet, but it’s a good start.
NRG Energy Inc., which licensed the car to grid technology used in the pilot, plans to try to power a building using the technology. They are applying for a grant from the California Energy Commission’s $6M fund for EV-to-grid research. Also, the Pentagon has a $30M project to try the concept at five bases, including Los Angeles Air Force Base this fall.
Hopefully, these projects will fall into place so that EVs can start giving back to the grid.
