Apparently methane gas forms under some lakes, dunno if there's enough to make it worthwhile to tap into for fuel?
Yeah, there's lots of nasty stuff inside the earth that comes belching out of volcanoes- not just ash clouds that spread out in the atmosphere to cut off sunlight, but also red-hot lava and toxic gases that blanket the ground.While watching the nat geo channel a couple of years ago, they were looking into why an entire village died overnight. Down in south American I believe. Anyway, they found out that due to a volcano outlet underneath the lake, large amounts of methane gas were let loose and would of course come to the surface now and then. If the wind was blowing just right, it blew it right into the village, and of course , it is lethal in large amounts.