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Hey, I was recently talking with a friend about alternative fuel sources (maily for automobiles) and primarily nitrogen. I am not 100% sure how the nitrogen that is used for nitrogen powered cars is obtained, but my friend thought that it is usually just taken from the atmosphere and purified. This is what brought about my question, as we then got into a discussion as to what would happen to the atmosphere if nitrogen powered cars became very popular, and the nitrogen was just taken from the atmosphere. My friend pointed out that if this became the case, that since nitrogen makes up a considerable amount of our atmosphere, something would have to replace it's void if we were to take a percent of it out of the air. He then presented his two opinions on what would happen: 1. Oxygen, or some other gas, would make up a larger percent of our atmosphere to replace the void of the disappearing nitrogen, and in the case of oxygen, we could suffer from oxygen intoxication if the percent of it in our atmosphere became to great. His other opinion was that, if nothing was able to replace the nitrogen, our atmosphere would more or less implode. So my question is: what would happen? Because after we discussed it a little further, we realized that the second opinion might not be right, given the fact that space is void of all matter, and therefore could not make the earth's atmosphere implode. Thanks.
Question Date: 2004-09-10
Answer 1:

Hmm -- it is a bit difficult to make a fuel out of nitrogen, despite the enormous binding energy of the molecule. Nitrogen really sticks to itself.

Unfortunately, if you made monatomic nitrogen, you would have the problem of storing it until you wanted to use it. It doesn't need any media to re-bind -- releasing all that energy. This is not to say that it cannot be done, just that I don't know how.

On the related question, Nitrogen makes up 78% of the atmosphere, and there is a lot of it: most of the earth is at sea level, where the mass of the atmosphere is 14.7 lbs/sq inch. So the mass of the Nitrogen is:
0.78*14.7*4*pi*(12*5280*3980miles)2 = 9.2x1018 lbs or 4.6x1015 tons. Assume that each person can drive and uses 20 lbs of nitrogen a week (which is somehow lost). Everyone could then drive for 4.6x1017/5x109 = 9.2x107 weeks or 1.77 million years.

In practice, it would be impossible to lose the nitrogen -- and very likely it would be released back to the atmosphere. If you did use up the nitrogen by making a solid or liquid waste, you would very slowly decrease the partial pressure of nitrogen which would lower the total air pressure, but not directly change the partial pressure of oxygen. If you have a reference or more information on how to make a nitrogen based power cycle, I'd like to see it. There are ways to use nitrogen compounds to release energy and produce nitrogen as a by-product. NASA uses such compounds in rocket fuels for thrusters. Unfortunately, most of these compounds cyanide, azide, etc., are very poisonous.

Answer 2:

Actually, this does not present a problem at all. To use nitrogen to power a car, I believe you would use pressurized nitrogen to mechanically move something while expanding the nitrogen back to atmospheric pressure. So any nitrogen removed from the atmosphere would eventually be returned. There would be some amount of nitrogen that would be removed from the atmosphere at any given time and stored in cars and other places waiting to be used but I suspect this is a relatively small amount.

Answer 3:

Two things:

1. Nitrogen is not a viable fuel source. Nitrogen in its gaseous form is largely inert - energy must be used to combine it with other compounds to do so. The alternative fuel source that you probably heard about is hydrogen. Go to the US Department of Energy website if you want to learn more about this technology at:

2.If you removed gas from the atmosphere, the atmospheric pressure would drop. However, if you somehow managed to take only nitrogen from the atmosphere, the oxygen concentration would remain the same. It would take up a larger fraction of the atmosphere, but would be no more abundant (there being less atmosphere to begin with). Thus, you would not notice anything trying to breathe, but several physical effects would be felt, these being (1) water would evaporate more readily and boil at a lower temperature, and (2) the entire atmosphere would become cooler for exactly the same reason that it gets scold when you go up into the mountains. However, since you are not reducing the amount of oxygen, you would not get altitude sickness.

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