Rising Sun for Electric Cars

  • 28/04/2008

  • Environment News Network (US)

Is my sustainability work consonant with the gravity of the climate crisis and the urgency of the ecological challenges we face? At Southern New Hampshire University (SNHU), as a complement to our work on renewable energy hedges, we are working to transform energy use on campus. One project underway is a system of grid-tied electric vehicles (Vehicle to Grid or V2G) combined with a solar photovoltaic charging system and smart computer control. The V2G plug-in hybrids and electric vehicles will replace traditional fossil fuel cars on campus and become an economic source of power for the electric grid during peak times. V2G cars can help balance the system load, reduce storage requirements, and reduce the need for fossil fuel baseload plants. Hybrids and electric vehicles can now use lithium ion batteries to become V2G plug-ins, either as original equipment or as supplementary aftermarket power modules. Lightweight lithium ion batteries have greater power density and are capable of thousands of charge cycles, making them suited to the grid's fluctuating need for power. On campus, we are designing a small, experimental, grid-tied parking lot that charges vehicles via an overhead photovoltaic (PV) array. The system will monitor vehicle battery charge, solar output, and New Hampshire electric system demand. With a real-time controller (designed, built, and tested by my associate Pentti Aalto), we can respond to price signals from the five-minute electric grid spot market (ISO-NE). A rise in demand on the electric grid is reflected in spot prices for power. When the grid calls for more power, we would feed in the available surplus from the car batteries and the PV charging system, thus helping to reduce spot prices and satisfy the system's demand for power. We plan to start simply with electric campus service vehicles, adding batteries to extend their range and improve V2G charging capacity. We'll then focus on converting hybrids owned by volunteer staff, faculty, or students, modifying them to be V2G plug-ins. The parking lot PV system will feed the grid directly, or charge the vehicle batteries. The vehicles will make money selling power into the grid during high load conditions by responding to five-minute spot market price signals above, for example, $.25/kwh. In the future, our V2G cars will act as power sources, making money for us and keeping the grid in balance. A V2G car with fully charged batteries (4 kilowatt hour capacity) could provide the grid 10 kW of power for 12 minutes (50 percent maximum discharge). Five million parked cars could provide 1,000 megawatts of power for an hour during peak times with a 2 kW total discharge. 1,000 MW is the size of a very large baseload coal or nuclear plant. Overall, vehicles optimized for V2G power could provide even more energy into the grid. In 2001, there were 230 million cars, trucks, and buses in the United States. Parking lot solar can be easily integrated into plug-in electric charging stations. It also provides shade for cars and can thus reduce the energy needed to cool a hot car when starting it up during the summer. The system can also markedly increase the value of the parking area without requiring the use of any new land. There is plenty of parking area in the United States