methane digester

From The Lexicon of Sustainability:

A system which captures naturally occurring gas from cow manure and converts it into electricity.
 
WHAT THE DIGESTER DOES (IN 30-40 DAYS)
1. saves money by generating 300,000 kilowatt hours of energy per year
2. eliminates a greenhouse gas 23 times more damaging than CO₂
3. converts nitrogen into a more usable form for plants
4. cuts down on the odor and flies around the farm
 
HOW IT WORKS
1. barn slurry, silage runoff, and creamery waste flow into the slurry pit¹
2. this mixture is pumped into a device² which separates the manure’s solids and liquids
3. the liquid flows by gravity into the digester pond³
4. anaerobic digestion = bacteria digest the waste and give off methane gas
5.  the methane gas fuels a generator that offsets the farm’s energy use by 90%
6. heat captured from the engine makes hot water used to wash equipment in the milking barn

The single largest source of pollution in the State of California is methane from cows.  At Albert Straus’s family dairy in Marshall, California, a methane digester traps methane before it can enter the atmosphere, breaking it down into solids and liquid fuel that can be used to provide enough electrical power to run the entire dairy operation. 

(Learn more about methane digesters at the Lexicon of Sustainability)

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