In reply to Dave Garnett:
> Yes, and any that is released into the atmosphere just leaks out into space - gone forever!
It's not such a big problem as people paint it. At the current rate of loss it would take an estimated 1,686,625,000 years to deplete that atmospheric Helium. I think we'll have other problems before then. It happens the annual rate of release into the atmosphere roughly matches the rate leaked in to space, but the size of the atmospheric reservoir is incomparably larger.
The problem isn't loss into space, it's the cost of fractionating it out of the atmosphere... It's a similar relative abundance to Neon and we fractionate that. I don't know how the cost would scale for Helium but it's ~ 1/5th of the temperature an 1/4th of the abundance so a super-naive estimate would be 20x the cost. Certainly more than fractionating it from fossil fuels.
Post edited at 19:37