Organic farm waste, also known as Manure, particularly cow, swine and chicken manure, is being used to yield energy in the form of methane, or bio-gas using anaerobic digestion technology. This technology not only helps farms manage their animal waste, but also produce part or all the energy their farm operation requires. By capturing and storing carbon dioxide from bio-gas into the ground, the bio-gas becomes carbon negative and scrubs our past CO2 emissions out of the atmosphere.
Why should I be aware of this?
Animal manure has become an alternative and renewable energy source due to the increasing world demand for energy and rising prices of oil and natural gas. Importance of renewable energy will continue to rise as demand for demand for energy from crude oil, natural gas and coal goes up.
With a steady rise in electricity prices large farms are implementing anaerobic digestion to reduce their utility bills and improve the environmental performance on the farm. Today the spotlight is on the increasing world demand for energy and the high cost of oil and natural gas. This has heightened interest in alternative and renewable energy sources, such as bio fuels, forests, wind, solar and animal manure.
The livestock industry is creating economic opportunity for agribusiness in Texas. Beef, dairy cattle, hogs and poultry manure, also known as feedlot biomass, can be put to practical use as a renewable energy source, with dry manure and liquid manure producing different types of energy. Manure can be used for gas, electricity and fuel for a boiler, or it can be burned directly for cooking or lighting.
All about manure energy
Rural societies have for long used dry manure for heating and cooking fuel. If the water content of manure is less than 20%, it can be burnt directly. Solid, dry manure includes manure from beef feedlots and dairy drylots.
Dry manure can also be burnt release energy for the production of biogas. Processing manure into fuel provides cleaner air and water. Some dairies get rid of manure by sluicing it off to lagoons, which produce methane that escapes into the air. Methane has a global warming effect that is 21 times that of carbon dioxide, so using the methane for energy production significantly reduces greenhouse gas emissions. Also, manure used biogas plant is not washed off land surfaces by rain and irrigation into local rivers and streams. This benefits the local watershed also.
Wet manure for bio-gas
Bio-gas can also be produced from wet manure from dairy cattle and hogs confined in enclosed areas. Biogas from manure can be captured and purified to yield pipeline grade methane that is chemically the same as natural gas. It can be used on the premises for electricity or to fuel boilers or other thermal applications. Pipeline grade methane can be transported by pipeline for sale to the local power grid to run electric generators. Manure deposited on fields and pastures, or otherwise handled in a dry form, produces insignificant amounts of methane. Methane is also a primary component of natural gas and an important source of energy.
Advantages of bio-gas from cow dung
- Cow dung gas is 55-65% methane, 30-35% carbon dioxide, with some hydrogen, nitrogen and other traces.
- Bio-gas may be improved by filtering it through limewater to remove carbon dioxide, iron filings to absorb corrosive hydrogen sulphide and calcium chloride to extract water vapour after the other two processes.
- Cow dung slurry is composed of 1.8-2.4% nitrogen (N2), 1.0-1.2% phosphorus (P2O5), 0.6-0.8% potassium (K2O) and 50-75% organic humus.
- About one cubic foot of gas may be generated from one pound of cow manure at around 28°C. This is enough gas to cook a day’s meals for 4-6 people in India.
- About 1.7 cubic metres of biogas equals one litre of gasoline. The manure produced by one cow in one year can be converted to methane which is the equivalent of over 200 litres of gasoline.
- Gas engines require about 0.5 m3 of methane per horsepower per hour. Some care must be taken with the lubrication of engines using solely bio-gas due to the “dry” nature of the fuel and some residual hydrogen sulphide, otherwise these are a simple conversion of a gasoline engine.
- A bio-gas powered train has been running in Sweden from 2005.
- T-systems a German based IT company has started using bio-gas based fuel cells to keep its servers cool and is able to cut energy costs considerably.
- In the suburbs of Seattle, a fuel cell, located at the South Treatment Plant in Renton, WA, consumes about 154,000 cubic feet of biogas a day to produce up to 1 MW of electricity. That’s enough to power 1,000 households, but right now it’s being used instead to help operate the plant.
- Kompogas’ Biogas facility in Otelfingen is a large scale composting facility where over 10,000 tons of material per year from about 100,000 people in the nearby community is turned into nearly 1.3 million liters of biogas.
- Bio gas run vehicles have a range of 250 -400kms. Like Volvo, worldwide many vehicles are being manufactured that run on biogas. Biogas can share distribution facilites with CNG and is currently used as fuel in more than four million vehicles. 
- U.S. Dairy Uses Renewable Energy from Manure
- Manure to Energy
- Biomass Energy: Manure for Fuel
- ↑ Ecofriend