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Cows produce as much CO2e as cars do!



Attempt to collect methane from the business ends of cows as the hot gases rise to maximize the concentration of methane running through a microturbine.


Use a concentrator and generator to turn dairy barn methane and biogas into energy in the form of electricity (kWh)


Category of the action

Reducing emissions from electric power sector.

What actions do you propose?

Attempt to collect methane from the business ends of cows (using hoods similar to range/stove hoods) as the hot gases rise to maximize the concentration of methane running through a microturbine.  There is research to be done on the expected percentage that can be captured at given barn temperatures and a cost/benefit analysis.  Microturbines are expensive but require little maintenance.


Use a concentrator and generator to turn dairy barn methane-rich air and biogas into energy in the form of electricity (kWh)

There is still research to be done to find a cost effective concentrator.  For example:

Fluidized bed concentrator – concentrate methane from barn? 5,000 cfm (100 cows) and 50,000 cfm (1000 cows) units available.


Info scoured from the net:

100 cows emit 45 MJ of methane per hour.

100 cows produce 124 MJ of biogas via biodigested manure

100 cows need 150 m^3/minute ventilation minimum (50 cfm)

A micro-turbine moves 15 m^3/minute of air and uses 414 MJ to produce 30 kWh so 10 are needed for 100 cows!  Need to concentrate the methane-rich barn air.

A 200 cow dairy farm can make use of a 30 kW generator


So, if we use a 30 kW micro-turbine and 200 cows as a unit basis, we need some 76 MJ extra biogas per hour from something and we also need a way to concentrate the ventilation methane to run it through the micro-turbine.

The micro-turbine doesn't move enough air to ventilate a barn.

  • Somehow concentrate the barn's methane-rich air
  • Increase the number of turbines and find more biogas (from pigs or chickens or agriculture waste) so more air can be run through the turbine - this isn't likely
  • Stick a tube into the cows to collect methane, might be an expensive procedure and has practical implications, but might be the only way


More info

  • Dairy cows "and support animals" use about 5 acres (2 hectares) of land each.
  • There are about 270 million dairy cows.
  • So they use  about 1.4 billion acres (567 million hectares) out of about 8 billion acres (3.4 billion hectares)
  • Dairy cows represent 17% of land used by cattle.
  • So Dairy farms could expand into existing cattle land to accommodate 30% more population.


So, how are methane-reduced farm practices implemented?

  • Governments might impose methane regulations on their farmers, but will the WTO disallow trade sanctions if foreign beef is from non-regulated farms?
  • A logo like fair-trade on methane-regulated dairy and beef products?



Who will take these actions?

farmers, investors, government

Possibly, a border tax adjustment (and national tax) to offset added expense/risk of GHG free Dairy Farms and Beef.  Explained:

Due to the well-known obstacles faced by any attempt of multilat- eral agreements on Climate Change (as in the case of Kyoto and Copenhagen Protocol), governments should act unilateral, in the di- rection of internalizing the social cost of pollution. One policy that has been repeatedly proposed to deal with this challenge is border- tax-adjustments (BTAs) that mitigate any distortions arising from cross-country differences in environmental policy. Such unilateral ac- tions are the focus of this paper. It is argued that if a country set its pollution taxes optimally, cooperatively or non cooperatively, while the other country does not impose any pollution restrictions, there exist BTAs that improve global welfare.



Where will these actions be taken?

on the farm

How much will emissions be reduced or sequestered vs. business as usual levels?

What are other key benefits?

"free" heat, fertilizer, CO2 enriched air sometimes used in greenhouses

What are the proposal’s costs?

capital cost of machines plus maintenance

Time line


Related proposals


From another proposal: Climatarianism: the low carb(on) diet you’ve never heard of  



2.45 kWh/cow/day.

1,000 cows, 100 kW of electrical capacity

30 kW micro-turbine seems efficient and would work for multiples of 330 cows or so.

Exhaust gas flow rate: 0.31 kg/s and 13.8 MJ/kWh

So, air density (1.225 kg/m3)

0.31 kg/s /1.225 kg/m^3 in l/minute = 15,183.6735 l / minute

so 15 m^3/minute or 535 cfm

50 cfm per cow

~10 cows at 50 cfm per cow (made an order of magnitude mistake earlier!)

methane 0.0364 MJ/l

so 0.0364 MJ/l * 300 l * 100/24 in MJ = 45 MJ per 100 cows per hour

13.8 MJ/kWh * 30 kWh in MJ = 414 MJ

biogas: 22.2 MJ/m3

biodigester output 1.34 m^3/cow day

22.2 MJ/m^3/1.34 m^3/cow * 100 cows /24 hours ~= 124 MJ


More references:

Cattle use about 4.9 acres - Land Area Required to Support One Lactating Cow and Her Supporting Animals for One Year (p. 27)

2005: The maps suggest that an area roughly the size of South America is used for crop production, while even more land—7.9 to 8.9 billion acres (3.2 to 3.6 billion hectares)—is being used to raise livestock.

About 1.4 billion cattle in 2005

2012: 269,877,654 cows

So 270 million cow * 5 acres/cow /8 billion cattle acres ~= 17%

3.4 billion hectare about 70 percent of the land used for agriculture globally is pasture