Re: The Future of Cars?

Posted by Natalie L. Smith on Jan 10, 2002 at 09:26
(168.216.227.156)

Re: The Future of Cars? (Mike Kremer)

Yes, it is true that dripping water on sodium peroxide generates oxygen. That is because a mixture of water and sodium peroxide is at a higher energy level than the mixture of sodium hydroxide and oxygen, due mainly to the instability of the peroxide. But, it is this very instability that means that you can not go out into nature and find significant quantities of sodium peroxide. Therefore, it must be, itself, generated. This generation process uses energy that must come from some other source and, since all processes involve some loss, you will probably use more energy generating the sodium peroxide than you will release from the reduction to hydroxide. Basically, we can't get around the Law of Conservation of Energy (in standard non-nuclear processes). Fossil fuels were formed in a process that concentrated a long collection of solar energy into a compact form, which is what makes it so "efficient" as a fuel. We burn a gallon of gasoline in a half-hour, extracting in short order the energy accumulated over quite a long time. The same can be said for any of the biologically generated fuels (wood, alcohol, etc.). We haven't yet found any really good substitutes. The other energy sources (batteries, hydrogen, et al.) are all generated in processes that involve using some other energy source to create the high-energy material (i.e. charged battery, molecular hydrogen). The energy source used to create these doesn't have to be fossil fuels, but it generally is, for economic reasons.
Rather than focusing on "alternative fuels" that turn out, upon closer investigation, to be not so alternative, I find it more interesting to examine the ways in which they can reduce energy loss. For example, one really interesting feature in the hybrid cars is the fact that they have an unusual braking system. Standard braking is done by pressing a pad against the moving wheel, allowing friction to slow the car. Friction is a process that converts kinetic energy entirely into heat energy. That heat radiates out into the air and eventually into the universe and is basically wasted. Then the car must burn more fuel to get itself back up to the speed at which it was already operating before it braked. This is why city driving is so much more wasteful than highway driving and wastes fuel regardless of the location. Every time you brake, fuel is "wasted".
The new hybrids have a different way of braking. When you want to slow the car, a generator engages with the moving wheel (axle?) and, as the car has to do work in turning the generator, this creates a drag on the moving wheel. Here, however, a portion of the energy is not lost as friction but, rather, saved as stored energy in a charged battery. The battery is connected in such a way as to provide a boost assist to the engine.
Ultimately, the hard answer is that the greatest savings can be made by all of us taking the time and trouble and sacrifice to apply energy conserving practices in our daily lives. FAR easier said than done! - - and d*** confusing at times.


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