Vehicle-to-Grid (V2G)


What is V2G? V2G or vehicle-to-grid refers to a protocol that allows electric, gasoline-electric hybrid, or fuel cell-electric hybrid cars to interact dynamically with the electric grid.  Essentially, the large battery bank in electric or hybrid cars can act like a sponge to soak up excess electricity from the grid, and supply it back to the grid when the demand is high.  The interaction with the grid is managed seamlessly by an on-board computer that interfaces with the electric utility company by an internet connection.  Of course, the electrical connection between the car and the grid (power cable and plug) must be heavy-duty enough to permit the flow of up to 80 A of current.


In the simplest implementation of V2G, the car can selectively charge (or discharge) its battery bank when it detects a drop (or rise) in the fluctuating price of electricity, so this represents an obvious cost-saving for the car owner.  But the real value of V2G is that the car can perform even more important load-leveling and balancing operations for the grid (such as peak power, spinning reserves, or regulation) and thereby obtain substantial revenue from the utility company.  In fact, calculations show that the revenue can reach a few thousand dollars/year. 


V2G and Wind Power: Load-leveling assumes even greater importance when electricity is produced using intermittent renewable sources.  In fact, large-scale V2G involving extensive fleets of cars may constitute the perfect intelligent storage complement to wind energy which is inherently intermittent.


Projects: Dr. Ajay Prasad is collaborating with Dr. Willett Kempton (College of Marine and Earth Studies) and Dr. Suresh Advani (Mechanical Engineering) to demonstrate V2G using the UD fuel cell bus, as well as an electric car (Scion xB).  The current goal is to implement software and hardware on-board the vehicle that will permit V2G operation.  Future projects will continue to improve the sophistication and reliability of the V2G protocol.  It is anticipated that a full grid-level implementation will become possible with a minimum fleet size of 300 cars.


More information, technical papers, and reports on V2G can be found here.


Here is an article on V2G on Discovery News.