Uses of Methane

Methane can be generated from animal manure, scrubed of impurities, stored, pressurized and used in almost any application where propane or natural gas would be a choice: A propane refrigerator can be run on methane;
A propane cook stove will run unmodified on methane;
Propane furnaces and water heaters work well on methane; and even a generator can be run on methane.

The real question is not what can you do with methane, the question is how do you get enough of it that it is useful? The usual approach is to have a bunch of farm animals that create enough of a manure problem that turning some of it into usable gas is nice little side effect of disposing of the problem.