In nations underdeveloped and developed, animal and human excrement are inevitable byproducts of animal/human existence and metabolism. They can also be a source of pollution and even a noxious presence (imagine driving past hog farms in Iowa), not to mention the spread of disease (e.g. when cattle farm runoffs pollute groundwater). As a result, developed communities sometimes go to considerable lengths to treat and detoxify excrement, i.e. spend energy and resources in the process. What if the average US cattle/hog farm could instead convert the excrement of 500 animals into a energy source?
In Indian villages, cowdung is traditionally mixed with straw, cast into lumps the size of a bowl, sun-dried and then burnt as a fuel - often the fuel for the fires over which meals are cooked (thus reducing the dependency on the other common village fuels: coal, trees/firewood and kerosene). At least 25 years ago, Indians started constructing biomass convertors, essentially large tanks where the natural fermentative breakdown of excrement was used to generate gases, that could then be piped to fuel cooking stoves, etc.
Here is a link to how one Indian company, among others, has shown that a "new biogas digester turns human excrement, cow dung, or kitchen garbage into fuel that can be used for cooking or generating electricity, simultaneously addressing two of India's major needs: energy and sanitation." http://money.cnn.com/2008/02/26/news/international/kahn_biogas.fortune/index.htm
I strongly believe that the Midwestern US states that have significant animal farms can benefit from such technologies. Importantly, the excrement is truly a waste, so converting it into a energy source makes sense. Contrast that with corn being converted into ethanol (corn should feed people and not fuel-guzzling cars!).
Univ. of Iowa