Re: Ok, let's do this.

Posted by Mike Kremer on Feb 24, 2002 at 22:50
(62.188.48.74)

Re: Ok, let's do this. (Dale)

Dale said-
"So letís set the boundary conditions. If we want to replace gasoline with hydrogen in an automobile we will need enough hydrogen to get 2,500,000 BTU when we combine it with oxygen. Thatís 40 pounds of hydrogen or about 8,000 standard cubic feet."

Well Im not about to disagree with you upon that. I will even admit that Hydrogen must cost at least 25% more than its equivalent of Diesel fuel.
But you are still thinking and talking diesel or gasoline engines. Admittedly it would be extremely difficult to usurp the conventional oil/gas burning engine since the whole kit and caboodle is tied into our present economy.

But the change must come. Ergo, emmission free autos in California and elswhere? I dont profess to have the answer...but I like to think I am steering myself or others in the right direction.
Consider the following truths--Gasoline engines are a lot less efficient than Electric motors.
(they waste heat, plus reciprocating conversion to rotary) Electric motors are the more efficient option BUT not if they use batterys. Since gasoline stores at least 9 times more energy per kilogram, than a lead/acid battery. I dont think todays Batteries will ever be used,
to heavy and not enough lead in the world.

You talk about the difficultys of Hydrogen storage. You are right its a problem, but you make it sound more difficult because again you mention Hydrogen/Oxygen combustion...as in, and in comparison with the conventional diesel engine. Hydrogen must cost at least 3 to 5 times more, per million BTU's (British thermal Units) than say 87 Octane? I find your 50,000 PSI rather too impracticably dangerous? But you are correct in saying if you compress Hydrogen and store it as a liquid- the container would need be strong and v heavy. A Hydrogen storage tank might occupy approx 5 times the volume of a gas tank (storing at 200 atm or 3000lbs) and weigh 250 lbs+ at least.
Yet I am still thinking Hydrogen.....because inspite of the above disadvantages you can push the gas into a metal, such as Magnesium where it will squash into the spaces between the Magnesium atoms.
And unbelievable as it may sound, you can actually store MORE Hydrogen inside the metal than you can as a liquid. Volume for volume.
**Northeastern University in Boston recently claimed that they can do even better. They used incredibly thin sheets of Graphite only one third of a billionth of a metre apart, and they reckon they can store 30 litres of Hydrogen on a single gram of graphite, which works out to an amazing 8000 kilometers per tank with your Hydrogen powered car **
(I assume they mean 30 litres volume gas?)
** I was looking for Hydrogen storage in Carbon Buckyballs..did'nt find it...but came up with this instead**

I am pretty certain that Hydrogen stored as a magnesium hydride, need only be stored at 200lbs pressure, with a pressure release valve leaking a small quantity to atmosphere when not being used by the Fuel Cell.
As I have stated elswhere, Fuel Cells are the subject of intense research today. Nevetheless one can find some info, by subjecting your favorite Search engine to:- 'Hydrogen Fuel cell'
I like to believe the Hydrogen Fuel cell electric car will become a reality in the near future.

**
Hydrogen Car



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