“optimized cow stomachs”

[kristopher]

"How Farms Across America Are Using Cow Manure For Renewable Energy"


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...

http://thinkprogress.org/climate/2013/12/09/3040781/farms-cow-manure-renewable-energy/

[TexasProgresive]

1. Mother Earth News long ago

had a story about a swine farmer in S. Africa, I think, who used methane from collected pig manure to run his whole farm. Now it should be realized that the burned methane does create another green house gas- CO2. Which is not as green housey as methane.

[kristopher]

2. What are the origins of the carbon in the biomethane?

To the extent that inputs are created with fossil fuels, the carbon is adding to the carbon load.

However, just like ethanol, most of the carbon is pulled down from the atmosphere and is part of the carbon cycle. This comprises most of the carbon and obviously doesn't add to the atmospheric carbon load.

The use of this methane as fuel displaces carbon based fuels, so that is a direct credit against the fossil inputs, roughly rendering the process carbon neutral.

[TexasProgresive]

3. That's true for ruminants belching and farting

as well as the decay of organic material.

I posted about that some time ago when people on the thread were going ballistic about naturally produced green house gases.

[kristopher]

4. Not unless you capture those gasses.

The fossil fuels displaced by using the methane as a fuel are very important in moving the whole process towards carbon neutrality.

[TexasProgresive]

5. So true

Except it would be hard to capture methane emitted directly by ruminants. Now, digesting manure and urine is quite possible and should be done on a large scale.