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jack action
#72
May7-10, 02:28 PM
P: 536
Let me add my 2 and stir the pot a little bit.

First, I'm a big fan of the IC engine in personal vehicle and I don't believe it will be efficiently replaced soon. Although, there is a lot of propaganda to make it the devil's machine. IMHO, the way it is overused is more responsible of the problems we have.

The problem with any engine (no matter the type) in a vehicle is to store the energy efficiently. Mechanically, you can wind up a spring, speed up a flywheel, compress a fluid, etc. Electrically, you need a battery. But no matter how you look at it (volume, mass, safety, cost, power, etc.), storing it in a liquid fuel that you will burn is pretty hard to beat.

Electricity in a vehicle, I see it used appropriately in two ways:

The first one is by coupling an IC engine to an "electric" transmission, i.e. a generator and motor(s). Although, weight could be a factor, the power transmission efficiency is usually better than any mechanical mean and the fact that it is an infinitively variable transmission means that the IC engine can be used at its best BSFC (for the hp needed) all the time. The locomotives use that system and I always wondered why it was never implemented in a personal vehicle (I'm sure there are drawbacks I'm not aware of, but with today's EV, I think it is a pretty similar technology).

The second way is railroad electrical vehicle. Electricity is only an advantage as long as you use the power as you produce it. If you have to store it (thus using a battery), it looses all of its appeal. The only way you can do that with a vehicle is by knowing the path of the vehicle such that it can be followed by a wire, hence some kind of rail system. Of course, this can only be used for mass transportation or merchandise. If society have to invest in electric vehicles, this would be my first choice. Removing all of those trucks crossing the country or building high speed trains replacing gas-guzzling airplanes would be a better use of the billion$ invested in the development of personal car batteries which, in the end, are still no match to a gas tank in so many ways, and nobody knows their environmental impact yet (which may be just as bad as air pollution). It is easier to change a few commercial fleets and the way they do business, than changing millions of individual minds. And the end effects on air pollution will probably be similar without the battery problem.

Now, without endorsing everything he said, I would like to bring some defense to sr241 (He seems lonely in its corner!).

First, I see a lot of people giving excuses for EV concerning their high cost or lack of practicality by saying that development is underway and all problems will be solved in the future. To me that sounds like "magic thinking" where there is a way that exists which has no drawback and only advantages. I've never seen this in any engineering field and if such a way exists, with all the time and money spent on EV, it would have been obvious by now. It is not.

And, if we assume that R&D is the solution to EV, how come we don't assume that it would be the answer to make a better rotary engine? It is easy to say that the only viable rotary engine is the one from the RX-8 and that it is not as good as traditional piston engines, but a lot more R&D went into the last one. A LOT more. Even EV have a lot more R&D than rotary engine. But, when you look at the development of the Wankel engine since its debut, a lot of technical progress has been made (especially in sealing), mostly due to Mazda's effort. And saying that they have high rpm (so what? They need a gearbox anyway) or that they need a turbo because of their low compression ratio (Compressing in a turbo or in a cylinder, what's the difference?) as drawbacks are just ridiculous and non-founded statements.

Finally, although I'm no expert on the subject - and neither a radical opponent - when talking about nuclear energy being safer than anything else, I'm a little skeptical. Never heard of Three mile Island or Tchernobyl? But I'm sure there are good excuses and it will never happen again.

It seems that there is not only sr241 that says stuff based on dreams on this thread. It's not because a theory is popular that it is true. You have to keep an open mind to make a discussion viable.