Many have heard about how cow farts and manure decomposition both produce harmful methane gas, which contributes to global warming pollution. What is less known, though, is that farms can convert cow manure into renewable biogas, which can power aspects of the farm and prevent that methane from reaching the atmosphere.
While it’s no “catalytic converter” method, it is slowly but surely making its way across America’s farms. According to statistics updated by the EPA in November, there are now approximately 220 manure-to-biogas conversion systems operating at commercial livestock farms throughout the United States.
As ThinkProgress reported last month, these so-called “anaerobic digesters” have been used on farms to help process manure for several years. They are essentially just airtight tanks filled with a special mix of bacteria similar to that of the stomach of a cow. Patrick Serfass, Executive Director at the American Biogass Council, calls anaerobic digesters “optimized cow stomachs.” Farm operators make “slurry” out of the cow manure by combining it with water, and feed it into the machine, which creates a biogas comprised of about 60 percent methane and 40 percent carbon dioxide. The gas is then collected, treated, and piped to a gas use device. The leftover “digester byproducts” (cow dung without its gas) can be used for fertilizer or potting soil, which some of the farms are selling for some extra revenue.
The systems are now installed at 181 dairy farms, 27 swine farms, 7 “mixed” livestock farms, 4 beef farms, and 4 poultry farms in the United States, according to the EPA.
The process has been so successful that one of the farms highlighted by the EPA is currently evaluating plans to build a biogas pipeline from their farm to feed biogas into an upgrading facility close to a natural gas pipeline. The farm, Baldwin Dairy, says it is also constructing a greenhouse complex to use biogas for heating, considering growing algae for biodiesel production or raising tilapia fish, and is anticipating using biogas for heat and possibly future electricity generation.
In the U.K., there is one farm that has gone so far as to have their entire operation powered by anaerobic digesters, as Renewable Energy World reports. Wyke Farms, the UK’s largest independent cheese producer and milk processor, spent $8 million and five years on their system that, together with two gas engines, now power the farm and dairy operation entirely.
