There's plenty of interesting work going on trying to make large trucks more fuel efficient. One such example is the company Wrightspeed, which has been building range-extended electric powertrains that companies like Fedex can use to completely replace the conventional internal combustion bits on their existing trucks.
"[They have] all the things you need to make the vehicle go," Ian Wright told Ars. Wright is one of the original founders of Tesla but more recently has been focusing his attention on bigger vehicles, "since they burn so much fuel."
Wrightspeed's powertrain consists of electric motors (one for each drive wheel) powered by a battery pack, which can either be plugged in and charged from the grid or by the range-extender, a turbine capable of running on number of different liquid fuels. This replaces the diesel engine, transmission, propshaft, and differentials one might normally expect to find in something like a delivery truck.
Clean delivery trucks will be a major boon for urban air quality. The Bronx, for example, has one of the nation's highest rates of asthma, which many attribute to the semi traffic crossing the borough on the Cross Bronx Expressway.
(Score: 3, Informative) by dj245 on Thursday June 11 2015, @06:41PM
Wrightspeed's powertrain consists of electric motors (one for each drive wheel) powered by a battery pack, which can either be plugged in and charged from the grid or by the range-extender, a turbine capable of running on number of different liquid fuels.
I'm a turbine engineer and I have to shake my head when ever someone plans a land vehicle with a turbine in it. I assume they are referring to a gas turbine on the Brayton cycle rather than a different sort of turbine. Small turbines are expensive to manufacture, expensive to repair, not fuel efficient (compared to small piston engines), and not very tolerant of fuel impurities. The only thing they have going for them is a high power to weight ratio. For a racecar or a showoff vehicle, maybe the drawbacks are tolerable. But for a commercial or consumer vehicle, a small diesel would be a much better option.
I'm sure someone will jump in and say that turbochargers have been successfully used in vehicles for decades. That's certainly true. But a turbocharger makes use of waste heat, so the efficiency doesn't matter. A turbocharger also piggybacks on the vehicle's existing oil and cooling systems, which mask the true cost and weight of a turbine-only solution. A small turbine engine also needs a LOT of acoustic insulation and much more extensive and higher volume air filtration system compared to a piston engine.
A small (less than 500kW) turbine might be 25-28% efficient. A diesel of similar size is going to be at least 40% efficient. That's a huge difference, and companies have been pouring R&D and CFD simulation time on small turbines for the last 20 years with only very small improvements. Small turbine efficiency will never beat a diesel.