Saturday, May 10, 2008
Happy Mother's Day! Here's another dubious gas mileage gadget!
The premise on this site is one I've seen before. So has Tony, the engineer behind Tony's Guide to Fuel Saving. The device takes electricity from the car's electrical system and uses it to generate a mixture of hydrogen and oxygen (which they, and a lot of promoters, call "Brown's gas," after Yull Brown, a somewhat shady huckster), which is then fed into the engine and burned. There's an obvious problem with this: You're spending more energy to make the hydrogen than you are getting back when you burn it. If you could take waste energy, like from regenerative braking or the exhaust heat, and use that to generate hydrogen, then you might have something worthwhile. A waste energy system would probably need a good way to store the hydrogen, since the best times for generating the hydrogen are not necessarily the best times to burn it.
Their system, however, is one that rules out being able to store the hydrogen for later use. They mix the hydrogen and oxygen to make "Brown's Gas." This very interesting page on Brown's Gas gives a very good description of the trouble with storing a hydrogen and oxygen mixture:
Since Brown's Gas is an explosive mixture it would be hazardous to store any quantity of it at atmospheric pressure. To compress it for storage would be criminally stupid.
A standard cylinder used for storing hydrogen contains just over a cubic foot of gas under about 150 atmospheres pressure. At that pressure it would contain the equivalent of about 5380 liters of Brown's Gas. That is 2880 grams or 160 moles. At 242000 joules per mole a cylinder contains almost 39 million joules or 36700 btu. There are two ways of looking at this. One is that the cylinder is a poor storage device since, for all its size and weight, it contains about as much energy as two pints of gasoline. The other is that each cylinder is the equivalent of 21 pounds of TNT in a steel tube. This is not something I'd want to have around!
Another interesting tidbit about that site is the very small amount of water the device actually consumes. This claim on their website is an interesting one to examine, and not just for the excessive use of bold print and the poor capitalization:
Water can be used to fuel a car when used as a supplement to gasoline. In fact, very little water is needed! only one quart of water provides over 1800 gallons of HHO gas which can literally last for months and significantly increase your vehicle's fuel efficiently, improve emissions quality, and save you money.The low water consumption claim would indicate that it doesn't inject very much hydrogen at all. They claim a quart of water lasts "months" in their system. A quart of water weighs 2 pounds, and 1/9th of the weight of the water is hydrogen. If a quart of water lasts two months, each month you'd get 1/9 of a pound of hydrogen into the engine. Suppose you used 30 gallons of gasoline in that same month. That's around 175 pounds of gasoline! The idea that such a tiny fraction of hydrogen in the system could improve mileage by 40% staggers the mind.
1) Auto makers have more than enough financial backing to add a $150 kit to their cars.
2) Big oil? Do they realize that Royal Dutch Shell has partnered with the government of Iceland to make it a hydrogen based fuel market?
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