Is the theory of Helium occurring in Natural gas validated ?

“Most of the helium that is removed from natural gas is thought to form from radioactive decay of uranium and thorium in granitoid rocks of Earth’s continental crust. …” read more here.

Sometime back I remember (or maybe I misheard) a NPR report disputing this theory. Anyone knows if there is a better theory ?

It sounds like a pretty good theory to me. Uranium and thorium are found in granite (and other rocks too). Granite is found all over the place, and both uranium and thorium emit alpha particles, which are helium nuclei, when they decay. It would be weird if this did not result in helium being found in underground gases.

There may also be other sources for some of the helium, but I do not really see any pressing need for a “better theory.”

It’d be a real stretch to come up with any other way it could get in there. Helium will escape really easily when you’re trying to form a planet (it can’t be trapped in compounds like most elements can, so it’s always a gas, and a fairly light one), so any helium present inside the Earth must have been produced there. Anything that produces helium from anything other than hydrogen is by definition alpha radiating. And uranium and thorium are the most common alpha sources in the material that makes up the Earth.

Seems helium will be very expensive in the near future once the National Reserve is used up. And it does not seem to be recycleable as helium escapes out of the earth once they are freed up.

Thus will civilization be destroyed by children’s parties and people making their voices sound funny.

“Not with a bang, but with a squeak”.

I never gave it much thought…and I never read anything about it. As a rational human being I certainly figured it was due to radioactive bombardment of hydrogen atoms

This is possible in principle if the “radiation” that’s doing the bombarding is high-energy protons and/or neutrons (that’s roughly speaking what fusion is), but it requires conditions far more extreme than any that are naturally found on or in the Earth. If there were fusion going on in the Earth at a rate sufficient to account for the helium we find, we would know it.

Where is all the escaped helium though? I understand it will climb very high in the atmosphere, but I don’t understand why it would actually escape the earth’s gravitational pull. Shouldn’t all the free helium end up in orbit around the earth somewhere in the fringes of space?

But if helium is being produced by radioactive processes inside the earth, then there’s a replenishment taking place. So are we actually using it up faster than it’s being produced?

Pretty darned slow replenishment, I think. After all, it has taken the whole time that the Earth has existed to produce the amount of helium that was there when we started extracting it, and we have already used up most of that.

Some small but nontrivial number of helium atoms will have velocity greater than escape velocity. That’ll depend on the gas temperature, but the upper levels of the atmosphere are actually quite hot, up to 1500 C if wiki can be believed. I’ll leave the actual calculation as an exercise for the reader…

This is also true of all gases in the atmosphere, and yes, we’re losing those, too. But since they’re heavier but have the same range of energies (due to being at the same temperature), it’s a smaller proportion of those gases that can escape, and thus we lose the heavier gases slower.

Well, my thought was since we’re talking on a scale of hundred of millions of years, the rate of production doesn’t have to be very great.

Well, it all depends on what you mean by “great”. But at a rough back-of-the-envelope, natural fusion processes in or on the Earth, over a timescale of billions of years, would produce about enough helium to fill a balloon the size of a thimble.

Don’t forget the solar wind. They probably play a more significant role in the removal of gas particle from the upper atmosphere than normal escape.

I only thought that because of the historic (is that still true?) association of helium with natural gas, a ready supply of hydrogen.

Does this even occur randomly? H + n -> He + e

Still very true. It happens because both require a natural reservoir to capture the gas. So if you find natural gas you will find some Helium. If there is a more Uranium in the rocks below you get more Helium, which is why the US has wells with such a large Helium content. The time the reservoir has exited is obviously the other factor. It is quite possible that there are some pure Helium reserves under there somewhere. But we don’t look for them, tending to look for hydrocarbons as a much more profitable enterprise, and find Helium as a side benefit (or contaminant, depending upon viewpoint.)

No, that’s nuclear fusion, and only happens in places with extremely high temperatures and pressures. Scientists call those places “stars”.

And besides, the addition of a neutron to hydrogen doesn’t create helium, it creates an isotope of hydrogen called deuterium. To get a stable isotope of helium you need two protons and two neutrons.

Okie, was just asking…btw I did account for the escape of an electron