Two of the vehicles, International DuraStar Hybrid bucket trucks, are being used daily. The trucks employ electric motors that aid in acceleration. A special braking system captures energy generated while decelerating and feeds it back to the electric battery pack that powers the vehicle. When the truck idles, the engine shuts off.
Like other Dominion medium-duty trucks, the hybrids run on B20 biodiesel, composed of 80 percent diesel and 20 percent vegetable oil. Company officials said the hybrids get about 9 mpg.
The savings in gas comes when one of the trucks is being used for work underneath a utility pole. While standard diesel trucks sit and idle the engine to power the needed truck accessories, the hybrid model uses electric motors to run the truck, and the diesel engine restarts only occasionally to charge the battery.
While the hybrid truck's price is just under $200,000, about $50,000 more than a standard truck, company officials are still evaluating whether the extra cost is justified.
The company also displayed one of three Toyota Prius plug-in hybrids. The cars were converted using an A123 Hymotion L5 plug-in conversion module, which costs about $11,000, and will achieve 100 mpg for between 30 and 40 miles before the battery pack need recharging, according to Dominion. The module installs in the spare tire well and weighs 180 lbs.
Dominion is using the cars to evaluate what effect plug-in hybrids will have on future electric demand and will share its findings with the Department of Energy.