Beyond mere self-interest, there are at least two reasons EEs might want to keep an eye on developments in alternative fuels for transportation. For power engineers, the odds are strong that most future vehicles will use electric motors, either exclusively or in some kind of hybrid arrangement. For the digiterati among us, there will be control and monitoring opportunities in the vehicle and up and down the distribution chain. That sounds suspiciously like jobs and opportunity. Welcome to the Next Big Thing.
Prime Movers
There's no doubt that gasoline prices have captured people's attention lately. Folks certainly see that we're using lots of petroleum fuel and importing much of the oil it's made from (Fig. 1). That leads to considerations of alternative fuels. In the big picture, alternatives to petroleum-based fuels will impact activities ranging from electrical power production to heating and transportation. But how will this specifically affect the way we drive?
Let's consider the vehicle power plants themselves before we see how they get their power. To use a Darwinian metaphor, the most successful new species to date are the gas/electric hybrids, though they're just getting into the marsupial stage—no longer an egglayer, but not yet a true mammal.
The most successful sub-species is typified by Toyota's Prius, in which the starter motor/alternator is incorporated into the drive train of a conventional gas engine. Honda's approach is a little more elegant, with an electric prime mover and a gas engine that keeps the batteries topped up. Someday, the true mammals will be all-electric. But like the opossum and the kangaroo, these petro-electric approaches will find ecological niches that allow them to survive well into the future.
Purely electric-powered vehicles have been built, and some are commercially available. But they face many natural enemies. Nonetheless, it's instructive to examine the fossils already left behind and encouraging to see how the survivors successfully deal with those enemies.
When Editor-in-Chief Mark David and I met with the engineers at General Motors' Advanced Vehicle Technology Center last March, they showed us a collection of the parts they'd salvaged from their EV-1 vehicles. The EV-1 project lasted from 1996 to 2003. GM made over 1000 vehicles and leased them (in California and Arizona only) for three years.
During the life of the program, returned cars were refurbished, upgraded, and leased again. You could drive an EV-1 55 to 95 miles on one charge of the early lead-acid batteries and 75 to 130 miles on the later nickel-metal-hydride (NiMH) batteries. Alas, after 2003, most of the cars were recalled and crushed (Fig. 2).
What struck me was how much the EV-1 electronics shrunk in physical size and cost over the program's seven-year lifespan. The EV-1's first inverters were about the size of a refrigerator door, and the last were less than one-quarter that volume. Something similar happened with the size of charging stations. GM's engineers said bill-of-materials costs had come down as well.
Toyota ran a similar lease program with an all-electric RAV4 SUV. At the end of the program, the company was going to strip and crush the vehicles, but it relented in the face of a powerful grassroots protest. The contractor installing solar cells on my roof has one of these RAV4s. Taking it back from him would be about as difficult as taking John Wayne's six-shooters.
GM's EV-1 and Toyota's electric RAV4 were quasi-production vehicles, as were Honda's EV-Plus and pickups from GM and Ford. But what's become of them?
GM showed us a couple of battery-powered S-10 pickups that had a 114-hp three-phase, liquid-cooled ac induction motor driving the forward wheels, and separate wheel-hub motors for the back wheels (Fig. 3).
These pickups stongly resembled the 1998-era S-10 electric research vehicles that GM leased and sold to a select few buyers. Only now, these trucks have been beefed up with the wheel-hub motors.
In the new versions, the wheel hub motors provide a 60% increase in torque when the driver calls for acceleration. Each generates about 25 kW. They also add 33 lb to each of the rear wheels, which is why they aren't used in the front of the vehicle. And, they add the possibility of electric anti-skid control.
Around the rest of the industry, Ford leased EV Ranger pickups from 1998 until 2004, when they were all recalled. Honda abandoned and recalled the EV-Plus in favor of the Insight.