I follow the work of the Appropriate Infrastructure Development Group (AIDG) pretty closely. Through education and business development AIDG promotes sustainable technologies that improve the quality of life in developing countries. AIDG has identified several sustainable technologies that can be made locally, with local â€œeco-engineersâ€. One technology AIDG is promoting in Guatemala is the use of Biodigesters.
Biodigesters are appropriate technologies that take advantage of the energy that is naturally present in animal waste and kitchen trash. As these waste products break down, whether in the ground, a compost heap, landfill, or biodigester, they release methane, a potent greenhouse gas. In contrast to the other waste storage and disposal methods mentioned, a biodigester traps the methane before it becomes a problem and stores it for heating and cooking. In this way, biodigesters can provide a sustainable substitute for the propane, kerosene, and firewood that many rural families in developing countries use to serve these needs. For those families that have to buy their fuel, a biodigester can save them hundreds of U.S. dollars every year. For those that cut trees down for firewood, a biodigester will save them time and help to prevent the deforestation that is becoming prevalent in places where large numbers of people still gather their own firewood.
Biodigesters also create high quality fertilizer.
In a biodigester, animal waste is converted into biogas and fertilizer. Apart from providing fuel to the family that uses it, a biodigester is also a source of high quality organic fertilizer the family can use on its crops. During the decomposition process in the biodigester, the waste is also sterilized. This means that animal manure, which has caused many health problems in developing countries when placed on fields with close to the ground crops such as lettuce or cabbage, can be used without fear of causing sickness. Disease causing bacteria, such as E. Coli, are killed inside the biodigester and never make contact with the plants.
In households that use bio digester gas instead of wood to cook with there is a measurable improvement in the occupants health. (Link)
Introducing this simple technology reduces pressure on natural forests, provides free high quality fertilizer, reduces food borne illness due to E. Coli, improves health and saves money. This is a win-win-win-win-win technology.
(some text above was taken from the AIDG website)