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Old 10-20-2006, 04:13 AM   #1
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New cars arrived

There have been many efforts to innovate automobile design funded by the NHTSA, including the work of the NavLab group at Carnegie Mellon University. Recent efforts include the highly publicized DARPA Grand Challenge race.

Relatively high transportation fuel prices do not significantly reduce car usage but do make it more expensive. One environmental benefit of high fuel prices is that it is an incentive for the production of more efficient (and hence less polluting) car designs and the development of alternative fuels. At the beginning of 2006, 1 liter of gasoline cost approximately $0.60 USD in the United States and in Germany and other European countries nearly $1.80 USD. With fuel prices at these levels there is a strong incentive for consumers to purchase lighter, smaller, more fuel-efficient cars. Greenpeace, however, demonstrated with the highly fuel efficient SmILE that car manufacturers aren't delivering what they could and thus not supplying for any such demand [citation needed]. Nevertheless, individual mobility is highly prized in modern societies so the demand for automobiles is inelastic. Alternative individual modes of transport, such as Personal rapid transit, could serve a an alternative to automobiles if they
prove to be cheaper and more energy efficient.
Lexus LF-A concept car at the 2006 Greater Los Angeles Auto Show
Lexus LF-A concept car at the 2006 Greater Los Angeles Auto Show

Electric cars operate a complex drivetrain and transmission would not be needed. However, despite this the electric car is held back by battery technology - a cell with comparable energy density to a tank of liquid fuel is a long way off, and there is no infrastructure in place to support it. A more practical approach may be to use a smaller internal combustion (IC) engine to drive a generator- this approach can be much more efficient since the IC engine can be run at a single speed, use cheaper fuel such as diesel, and drop the heavy, power wasting drivetrain. Such an approach has worked very well for railway locomotives, but so far has not been scaled down for car use.
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Old 10-20-2006, 06:16 AM   #2
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Re: New cars arrived

first of all, this post is spam....2nd, i think it can make for some good debate lol

Originally Posted by mambonumba1
Such an approach has worked very well for railway locomotives, but so far has not been scaled down for car use.

I don't think railway locomotives use diesel electric because of it's fuel efficiency or it's simplicity. Producing vairable speed AC motors with that kind of current draw is reasonably complicated. Do you have any idea how many gears a train would need to pull 3 miles of fully loaded rail cars using a traditional diesel engine with a standard transmission. That's a lot of double clutching! and it just wouldn't work, as the tounge on rail cars allow each car to move closer/farther from the car it is coupled to. Everytime you depressed the clutch the cars would move back and forth.....
Electric motors produce nearly 100% of their torque at any speed (as long as you can keep em cool) so this works very well for locomotoves.

as anyone who uses a generator for a couple days when the power is out at their house can tell you, an internal combustion motor coupled to a generator head is not very efficient at all.
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Old 10-20-2006, 09:26 AM   #3
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I deleted the links and the member but I am going to leave the topic for debate.
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Old 10-20-2006, 11:38 PM   #4
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Talking to a gentleman who is involed with battery technology I know (he produces large industiral batteries not dissimilar from those in hybird cars) I found out that there is not nearly enough nickel in the world for every car in just the US to be replaced by hybrids. On top of that, the mining for the various metals in the batteries is destructive to the Earth. All this from a guy who makes a living off producing the things! While the gaoline-electric hybrid is a step in the right direction, it is essentially just a band-aid fix.

The gentleman I talked to as well as myself after some research do believe that diesel-electric hybrids using capacitor banks rather than traditional batteries is a possible solution. The diesel fuel can all be bio-based while capacitors have a much longer life expectancy than traditional batteries and utilize far less toxic components. As it is, a 400 farad capacitor that will run at 12 volts nominal can be packaged into some thing about the size of a 12v, 5 ah AGM rechargable battery. While the price is prohibitively high, with time and technology, things can only improve.

One thing I really do like about the hybrid cars is the regenerative braking. You look at our vehicles and it is startling just how inefficient they are. We waste energy to get them moving and then waste it again to slow them back down. The regenerative braking on an electric car really is a simplistic design. To do the same with our traditiona internal combustion engines would require some sort of hydraulic accumulators or similar whereas the hybrid cars really only require a means of switching the polarity.

What's really interesting about electric motors is how their torque relates to their rotational speed. An electric motor freewheeling will produce no torque. However, at its stall speed (not moving due to load) it produces peak torque. This drivetrain shredding torque "curve" lends itself rather well to automotive use. The fact that peak power comes on so low is what makes diesels to well suited to use in semi trucks and diesel-electrics so great for a train. Momentum is a bitch, but electric motors fight that, albeit with some serious heat as a side effect.

Unfortunately, horsepower is defined as (torque*RPM)/5280 so at max torque that electric motor isn't producing any horsepower unlike an internal combustion engine. Without going into a lot of ugly physics and calculus (no one likes to calculate rotaitonal acceleration....radians are the devil), I think it's easy enough to see that horpower is really a function of how fast that electric motor is spinning. Peak torque on one end, peak horsepoewr on the other. Somewhere in the middle lies that sweet spot, just like a theoretical internal combustion engine. Of course it is much easier to hit that sweet spot on an ICE versus an electric, but with some tweaks to our gearing devices, things will happen I think. The continuously variable transmission hold a lot of hope as they are much more efficient than anything involving hydaulics like a hydrostatic or traditional automatic transmission without the the limited gearing of a manual gear-on-gear type transmission.
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