I read above that some work as been done investigating whether muons could be used to catalyze fusion of deuterium and tritium. Apparently they can draw the particles closer together so that the electric repulsive force between the nuclei can be overcome at much lower temperatures than required for thermonuclear fusion. One of the issues faced with actually producing net positive energy from the reaction seems to be coming up with an efficient muon source.
According to the above link, muons arrive "at sea level, with a flux of about 1 muon per square centimeter per minute."
Could these atmospheric muons be used as a catalyst source? With only one per minute, you wouldn't get a whole lot. But could you get at least get some usable electricity out of the setup?