Wednesday, August 20, 2008

Thank Gas

Thank Gas It’s Wednesday

Today’s article is brought to you courtesy of that state of nature referred to as the gaseous state. Gases have interested scientists for many thousands of years and it took more than three thousand years to develop the kinetic theory of gases. Heron a Greek who lived in the first century invented a steam engine, long before a couple of Brits named Savery and Watt harnessed the power of steam and are wrongly remembered as the inventors of the steam engine.

Three are all sorts of laws covering the physical behaviour of gases. These include Graham, Boyle, Charles, and even a French scientist and politician named Gay-Lussac. My favorite is the Ideal Gas Law. A gas is ideal if its pressure increases in perfect proportion to the absolute temperature. If the increase in pressure is not in perfect proportion to the absolute temperature then the gas behaves imperfectly and has a fugacity coefficient that is not unity. It seems like political candidates of the male species repeatedly behave imperfectly and hence have the audacity to deny to the popular press that they did not exhibit some fugacity. Of course French politicians are allowed to openly display an enormous amount of fugacity.

CNN is now carrying news of a Compressed Air Car that will propel the world with little fuel. Actually, I hosted the California promoter of this contraption at my home in Tiburon about five years ago. I took a quick look at the proposed vehicles and told the promoter it simply would not win any major share of the vehicle market. The inventor of the Air Car is a Frenchman named Guy Negre who wants to be the next Gay-Lussac and have a gas law named after him. Negre has further developed his compressed air car to now use fuel to increase the range and speed of his car. Actually he now has a car that is gasoline or diesel car that is augmented by compressed air, sounds like a turbocharger to me so why compress air into a scuba tank and waste the wonderful form of energy called electricity in what turns out to be an inefficient, bulky and Rube Goldberg like contraption.

If one already has electricity, it is a lot more efficient and simple to store this electricity in batteries on board a vehicle. Now the inventor of the pure air car realises he has to obey the gas laws, he has abandoned the pure air car for the hot air car. Just today CNN online aired the story of 106 miles per gallon for a six seater air car. Yes it is 106 miles per gallon without including the electricity used in compressing the air and therefore the fuel that was used to generate the electricity. Perhaps the 106 miles per gallon was also achieved travelling down hill so that the added mass of the scuba tanks and compressed air contributed to gravity’s pull on the contraption. One can store about 100 watt hours of energy in a kilogram of compressed air at 200 atmospheres pressure. By comparison a 3 fluid ounce double shot glass full of diesel has 1,000 watt hours of stored chemical energy or about ten times as much. Also for its storage diesel does not need a scuba tank that is also much heavier than a diesel tank. Please do not use your double shot glasses to drink diesel even though it is truly fire water.

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