A few repolies to your two replies, yours and MrAcheson's.
First, what do you mean by a fuel cell? You talk about "burning the hydrogen" but in a fuel cell the hydrogen is reacted non-exothermically. The fuel cells that I was looking at about twenty-five years ago, like the electric power generator in the support module for the Apollo lunar spacecraft, react a fuel and an oxidizer, dissolved into electrolytes, generating electricity at the surface of the membrane, with no moving parts. Here is a web page of a manufacturer of small fuel cells with an illustration showing how they work. Fuel cells are exempt from the limitation in efficiency of heat engines described by the Carnot cycle; I've heard of fuel cells which achieved greater than ninety percent thermal efficiency!
Now that, after decades of development, manufacturers have worked a lot of the bugs (mainly membrane problems, I think) out of production fuel cells there's a lot of commercial potential, not so much for vehicles as for fixed power generation. Rather than electric power suppliers wasting energy due to the resistive loss in long power lines, power companies will be able to transport energy with much smaller losses by fuel trucks or buried pipelines to small, clean generation plants near the users. As I live in Florida, where there's more than enough sun (I wonder what percentage of Florida's electric power generation is used to run air-conditioners) the idea suggests itself to combine local fuel cell generation with extensive solar power exploitation; a fuel cell can (at least in theory) work in reverse, taking in current from banks of solar panels and electrolyzing water back to hydrogen and oxygen, to be extracted from the electrolyte and stored for fuel for night-time power generation.
Second, you were complaining about the limited size of today's production hybrids. I suppose the Corolla-sized Prius is a bit too small for your tastes (not mine, though, my family - me, my wife, and three kids - have been satisfied with the four Corollas we've owned). But did you have a look at that Ford Escape HEV link I supplied? That's a hybrid-powered SUV! You can easily carry your "four people plus luggage" in that. It's interesting to note that whereas ordinary cars get a better figure in EPA highway driving than in city driving, Ford estimates that the city mileage of the Escape HEV will be 40 MPG, while the highway mileage will only be in the high twenties. I guess that's the barn-door aerodynamics and huge frontal area of an SUV coming into play at highway speeds; even if you had a 100% thermally-efficient power train the limiting factor on a poorly-streamlined vehicle like a typical SUV would be aero drag loss.
Third, of course the tzero is not a practical vehicle, but then it isn't a mass-market production car, just an interesting technology demonstration. The reason I brought it up is to show that a purely-electric car is not necessarily limited to toy-car performance, but can have race-car-like acceleration. Don't be misled by that 200 HP figure; have a look at the power and torque curves of an automobile electric motor as compared with an ordinary gas engine, or even worse a turbocharged engine. For example you can get 250+ HP out of a street-legal turbocharged Miata 1.6 engine but you won't see even half of that horsepower until you rev it up over 5000 RPM, which is about where most people upshift. Whereas the power curve for an electric is as flat as a table, you're getting all that power from clutch slip all the way up to red line.
Fourth, I don't understand what the problem would be with regenerative braking. You don't need a big auxiliary system for braking alone, it's the same motor that drives the wheels under power. Apply current to an electric motor and it produces torque, or conversely apply torque and the motor produces current. Of course the problem isn't that simple, there are many mechanical subtleties involved. The most important is that for emergency braking the negative g force required is higher than the positive g force the motor can supply (maybe not for the tzero though) so you need to supplement the regenerative brakes with good old-fashioned "wasteful" braking systems, and then there's all the control circuitry. But hey, think of it like those inner-city "midnight basketball" programs; problems like that give technologists something besides dreadful new high-tech weapons to keep them occupied.
Finally, I wouldn't call someone "ignorant" over a difference in terminology, even if that is the K5 way. The term "electric car" isn't defined in some programming language spec, you know. I call the Prius and Insight "electric cars" because the wheels are driven by electric motors. Also, the idea that electric motors are inefficiently heavy is untrue; in fact, the small size, light weight, and broad torque band of electric motors are some of the feautures that makes them so appealing to vehicle designers. Rather than a complicated and heavy drive-train and gear-shift mechanism, one mounts the motor adjacent to the driven wheel and supplies it with power by a wire. As an extreme example of the weight-to-power efficiency of electric motors, my uncle designed the electric-powered liquid hydrogen pumps for the Saturn V. The pump's motor (it had superconducting windings, cooled by liquid hydrogen!) was small enough to pick up with one hand, and it produced one hundred horsepower at the shaft.
Yours WDK - WKiernan@concentric.net
The one thing that really disturbs me about America is
that people don't like to read. - Keith Richards
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