Green Technology.

Vehicle-to-Grid Technology.

Electric Car Networks Represent Another Energy Storage Solution.

Right after reading Brian Albright’s piece “Energy Storage Solution Full of Hot Air,” I came across an interesting energy solution in a Scientific American blog post by Lesley Evans Ogden. This article discusses the history and commercialization of vehicle-to-grid technology (V2G), which was developed by Willett Kempton at the University of Delaware along with Vermont’s Green Mountain College economist Steve Letendre. The concept is to create a network of electric vehicles (EV) to act as batteries, charging the EVs’ batteries during slow energy usage times and feeding the energy back to the grid during high demand.

This would be extremely useful in micro-grid applications and in applications using solar and wind energy generation. Professor Kempton sold his rights to this technology to Danish company Nuvve last June. They, in turn, have licensed NRG Energy of New Jersey to develop this concept in the U.S. This service will initially be implemented to large fleet owners of EVs but could be rolled out to individuals as early as 2015.

The upside of this program is not just in the pockets of the large energy producers, who will have more control over regulating energy generation and distribution, but to the car owners, who stand to make as much $10,000 over the lifetime of their electric vehicle. The downside, battery life can be shortened because of more discharge and charging cycles. Still, a pretty cool idea that is being piloted right now.

When one sees the term G2V it is understood to refer to the normal process of using the electric grid to charge the battery of an electric vehicle. V2G however is better understood as using the battery as a source of electric energy. The discharge of the battery to generate electricity may or may not have a connection to the grid. There are a variety of applications for the technology; Vehicle-to-House (V2H), Vehicle-to-Building (V2B), and, of course, V2G.

Built from a 2006 Scion xB that was stripped of its internal-combustion engine and related systems, the eBox uses a drive system consisting of an ac induction motor, inverter, bidirectional charger, and battery management system. Capable of 0-60 mph (97 km/h) in 7 s, the eBox has a top speed of 95 mph (153 km/h), energy consumption of 220 to 320 W·h/mi (354 to 515 W·h/km), and driving range of 100 to 145 mi (161 to 233 km).

With 5088 cylindrical cells, the eBox's lithium-ion battery pack has 32 usable kW·h at a nominal charge of 345 V. The eBox's drive system provides 120 kW of propulsion power and up to 18 kW of charging power.

In the summer of 2011, DTU researchers took delivery of an eBox to further their V2G research efforts.

According to Peter Bach Andersen, a Ph.D. student involved with V2G research at DTU's Centre For Electric Technology (CET), ongoing investigations at the center include grid impact studies to determine how the electrical power distribution system handles the power consumption needs of EVs, as well as smart charging scenarios in which the timing of an EV's recharging is based on energy costs, grid capacity, and other factors.

"While DTU has done some EV research before, it has never been with a V2G-capable EV. The eBox is one of the first EVs in Denmark to have this capability," Bach Andersen told AEI.

Denmark's offshore wind farms will factor into CET's V2G research tasks.

EV charging will be indirectly linked to wind production via the energy market. If a lot of wind energy is available during certain hours, the energy cost will be lower and the EV will choose to charge at those hours.

"Smart charging should, in general, support better utilization of wind energy," said Andersen. "And V2G can move this EV/wind synergy even further by delivering stored wind energy back to the grid at later times. Future power markets will most likely facilitate a tighter link between EVs and wind."