FREDERICK, Colo. --- UQM Technologies, a developer of alternative energy technologies, announced it has received an order from the Denver Regional Transportation District for generators and motor controllers to retrofit an additional 18 hybrid-electric mall shuttle buses. Each 45-foot hybrid electric mall shuttle bus will be retrofitted with a 35 kW generator and two power electronic motor controllers to control the operation of the electric propulsion motors now installed in each bus. This order represents the balance of the equipment necessary to complete the retrofitting of RTD's entire hybrid electric mall shuttle bus fleet. Denver RTD introduced its hybrid electric fleet of MallRide shuttles in 2000, the first large-scale deployment of hybrid electric buses for transit use in the United States. A total of 36 MallRide shuttles operate on the 16th Street Mall in downtown Denver, providing a free ride for passengers across the 1.3-mile long 16th Street Mall. The hybrid electric MallRide shuttle buses are powered by a compressed natural gas fueled 2.5 liter Ford industrial engine that operates at 2,200 r.p.m. and will turn the specially designed generator to produce electricity to recharge the bank of batteries that power the shuttle. The specially designed motor controllers feature regenerative braking, a process in which kinetic energy is converted to electrical energy through the braking process. This electrical energy can also recharge the battery pack. Each 45-foot MallRide shuttle bus features a low floor design (14 inches above street level) that makes it easier for passengers to step on and off the bus and can transport up to 116 passengers. "Our systems have now been in daily service on the 16th Street Mall for well over a year, and this order will ensure that all MallRide shuttles will run for many years to come powered by reliable, high-performance UQM equipment," said William G. Rankin, president and CEO of UQM Technologies Inc. Denver RTD serves the eight-county greater Denver metropolitan area.