When Tesla introduced its Ludicrous mode, that might have been the turning point for some to see electric cars in a new light. Soon, however, semi-trucks might become the greatest evangelists for the merits of electric powertrains, and for the same reason: because electric semis could be a heck of a lot quicker.
Case in point: Toyota’s Project Portal heavy-duty semi-truck, revealed this week, leaves its diesel-drinking cousin in a cloud of . . . well, nothing except a little water vapor. And it makes a strong argument for electric powertrains in semis, whether fed by hydrogen fuel cells or battery packs.
As shown in the video below, the hydrogen-fuel-cell-powered electric semi, loaded with cargo to a gross vehicle weight of 35,000 pounds, took 8.9 seconds to go approximately 400 feet—that’s about a third of a quarter-mile, for those familiar with the drag strip—versus 14.6 seconds for an equivalent Class 8 diesel truck carrying the same load.
According to Takehito Yokoo, senior executive engineer with Toyota Motor Research & Development, there are two things that allow the fuel-cell truck to beat the diesel so soundly, especially at lower speeds. One of them is gearing. Diesel semis can have gearboxes with up to 18 speeds and need to be kept in a relatively narrow rev range—often 1300 to 1500 rpm—for best acceleration. The fuel-cell truck, on the other hand, is a fixie; its set reduction ratio of about 15.5:1 gives it good motor pull from a start and allows it to cruise at a normal U.S. highway speed.
Also key to the Toyota project’s strong (and almost silent) performance is a 12-kWh battery pack that behaves almost like a capacitor, recharging during lower load conditions and discharging rapidly to release an extra 200 kW at full throttle, for about a minute, adding to the two fuel-cell stacks’ combined 228 kW and contributing to the motor system’s 670 horsepower and 1325 lb-ft of torque.
Faster-moving semis could increase the efficiency of the rest of us, too, easing congestion on urban freeways, where merging semis can clog the right lane. Electrified heavy-duty hauling might not be ludicrous at all.
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