The timing of EV recharging and its effect on utilities

Electric vehicles (EV's) represent an important future load on the electric utility system which, if properly managed, could increase power plant utilization and reduce the average cost of generating electricity. A future EV population of 7.5 million is addressed, together with its characteristics, vehicle use, consequent recharging loads, and the impact of EV's on electric utilities in terms of the generation of electric power, fuel use, and costs. The impact on utilities will depend in part on when the vehicles are recharged. If the price of electricity is uniform throughout the day, recharging is likely to begin when vehicles are parked at home. Most of the recharging would then occur during late afternoon and early evening hours when other demands for electricity are high. In the year 2000, peak electricity demand would increase by 5700 MW, and oil- and gas-fired power plants would generate 39 percent of the recharge power. Marginal generating costs would average 7.6 cents/kWh in 1982 dollars. If electricity were priced by time of day, recharging could shift to late night hours when the other demands for electricity are low. The peak demand would increase by only 400 MW; 27 percent of the power would come from oil and gas, and marginal generating costs would average only 5.1 cents/kWh, some 25 percent less than the marginal cost of the system load without EV's. The fuels to recharge EV's were found to vary from one region of the country to the next. Utilities in the northeast would use the most oil and gas for recharging (more than 75 percent), while those in the central part of the country would use the least.