It is our feeling that electric vehicles hold great promise for dealing with some of the transportation issues we face as a society. In addition to being pollution free at the point of use, we appreciate the promise that they are more efficient than the internal combustion engine, and that they have the potential to be run by solar energy. TFS has been using a newly purchased Nissan Leaf since the beginning of May and we have been tracking the energy consumption and the mileage on a daily basis. Our prorated mileage for the month will be 685 miles. The energy use will be 142 kWh.
The photovoltaic system needed to provide the power for this amount of driving would be less than a 1 kW system. If you plan to drive 15,000 miles per year, you would need a 2kW system or smaller. After incentives, such a system would cost less than $4,000.
After the initial investment for the solar photovoltaic system, you will effectively eliminate the ongoing operational costs. However, even if solar is unavailable to you, the financial cost to operate the vehicle is relativity minimal when compared to the cost of a gallon of gasoline. In TEP service territory, the cost of electricity is about $0.10/kWh. This means the cost to drive 685 miles will be just $14. A Prius getting 50 MPG would use 13.7 gallons for the same driving distance, which would cost just about $50 at $3.50/gallon. The numbers look even better if you are comparing the Leaf with a vehicle getting lower fuel efficiency. In comparison to a Honda Civic which gets 32 mpg, the cost would be about $75.
If you are looking at this from a carbon saving point of view, the benefits are not as significant. Drawing 142 kWhs from the grid would produce 312 lbs. of CO2 from coal generated electricity, while a single gallon of gas produces 19.4 lbs. of CO2. This means that at 42 mpg, the carbon emissions are equal. If, however, the energy comes from solar, the Leaf cannot be beat.
The usable range of the vehicle, given the way we drive it, seems to be about 60 highway miles and 100 city miles. We have driven up to 80 miles in a day, with about 25 miles left on the battery, while on another day we have driven just under 60 miles with only 8 miles left on the battery. We have found that performance in city traffic ranges from 4.3 to 6.3 miles/kWh, depending on how conservatively we drive. On the highway driving to Green Valley, the performance dropped to about 3.5 miles/kWh.
It is important to know that we try very hard to get the best mileage we can out of our vehicles and that these numbers might not be as rosy for a normal driver. Regardless, the potential of electric vehicles is exciting, particularly if we continue to transform our energy infrastructure into a more distributed and renewable energy based model.