User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-575012-20121009212211/@comment-5043481-20121010152256

That may work, but methane does not have as much lifting power as other gases.

Air has a density of 1.2 kilograms per meter cubed. (I shall omit units as they are all the same, for the sake of breivity.) For a gas to be lighter than air, and therefore lift, it must have a lower density. Methane (and also ammonia) has a density of 0.7. This is 6/10 of the density of air. However, helium has a density of 0.2. This is 1/6 that of air. However this does not matter as helium is scarse and cannot be produced organicly.

Hydrogen however, can be produced organicly, and has a density of 0.1. This is 1/12 that of air. Hydrogen has 7 times as much lifting power as methane. It is actually the main component of most farts.

Your theory does deserve some credit though, as hydrogen (and helium) will quickly leak out of a permeable container. A latex helium balloon will deflate in 8 hours. Methane finds it harder to pass through these membranes and so will stay inflated for longer.

Hydrogen is supirior!