Anaerobic Digestion of Manure to Yield Methane
Anaerobic methane digesters has been used for years to reduce energy costs on farms in Europe and North America. The digesters operate by using anaerobic bacteria to break down animal waste. During the process, which typically uses a tank heated to about 100℉ (38℃) to speed the reactions, raw manure is broken down and methane is produced. The methane can then be used to generate electricity or produce heat.
For a dairy farm in with cows, the cost of installing a digester is approximately $. Assume that the farm uses kWh of electricity each year at a cost of $ per kWh. The waste from a single cow can produce 3.0 kWh of electricity each day. Assume that the cost of electricity remains constant and the farmer uses all of the manure from the cows in an anaerobic digester to produce electricity on the farm.