Commercial vehicles with frequent starts and stops in their drive cycle. Wrightspeed (Ian Wright co-founded Tesla) has a gas turbine-electric hybrid module that can easily be retrofitted into existing vehicles.
Of course, since Wrightspeed’s power-trains are going into trucks, the whole thing is on a much beefier scale. Wright told me, “Our motors have four times the power-to-weight ratio than anything else available.” Additionally, like most EVs, their technology uses regenerative braking — which puts energy back into the batteries every time the brakes are applied.
Consequently, Wrightspeed’s technology lends itself particularly well to commercial vehicle applications where frequent start-stop cycles occur — a feature common with a typical package delivery or garbage truck. “A thousand horsepower easily goes into the brakes of a commercial truck,” when such vehicles are brought to a stop, says Wright. In a conventional truck, that energy is wasted, but when you consider 1,000 horsepower is the equivalent of about fives times the peak horsepower of most family cars, that’s worth capturing.
The energy captured by regenerative braking is fed back into the lithium-ion phosphate batteries Wrightspeed uses — a battery chemistry particularly suitable for developing the high power necessary for their electric-drive motors. When the batteries are depleted, the range extender kicks in which is calibrated to run constantly at the most efficient speed to generate the most power. A benefit of using a gas-turbine range extender is that it runs very quietly — considerably quieter than a diesel engine, Wright said, which is a worthy attribute when trundling through residential areas.
So, what does all this add up to in terms of efficiency? Wright told me the average garbage truck travels about 130 miles a day with around 1,000 hard stops, gulping down around 14,000 gallons of diesel a year in the process. Wrightspeed’s power-trains use less than half that amount of fuel, with the added benefit of very significant emissions reductions.