Composting animal mortality reduces carbon dioxide emissions

By replacing a diesel fuel-fired carcass incinerator with an animal-tissue compost facility, a swine finishing facility could reduce carbon dioxide emissions by nearly 60 percent.

Consumers and farmers alike are becoming more aware of climate change and the greenhouse gas emissions associated with the production of food, fiber, feed and biofuel crops. Commodity organizations are developing tools to help farmers determine the carbon footprint of their production practices. These tools are available online for dairy and pork producers.

Earlier this summer a farmer asked Michigan State University Extension to help design an animal-tissue compost facility to process mortality from his swine finishing facility. His old carcass incinerator was worn out and simply too costly to continue to operate. By replacing the carcass incinerator with a mortality compost facility, he was able to reduce his carbon dioxide (CO2) emissions by 58 percent and save on fuel costs.

The U.S. Environmental Protection Agency (EPA) reports each gallon of diesel fuel burned will release 22.2 pounds of CO2 emissions. Research from the University of Nebraska- Lincoln (UNL) reports that one to three gallons of diesel fuel are required to incinerate 100 pounds of animal tissue. Because the farmer did not track annual fuel use for incineration, the assumption is that he was an average user of diesel when incinerating carcasses and used two gallons of fuel per 100 pounds mortality.

Using the Spartan Animal Tissue Composting Planner, this 9,600 head swine wean-to-finish facility annually accumulates about 88,695 pounds of animal mortality. Based on EPA’s CO2 emissions from diesel fuel, the farm was emitting 39,382 pounds CO2 annually by burning the fuel required for incineration. Using the UNL estimated fuel consumption, incineration of the mortality required 1,774 gallons of diesel fuel.

In measuring CO2 emissions from composting, MSU Extension swine specialist Dale Rozeboom reported that 3,520 pounds CO2e would be emitted from a mortality compost facility serving a 2,000 head swine finishing facility. By extrapolation, the 9,600 head swine finishing facility would emit 16,896 pounds CO2e annually from mortality handling. By changing mortality handling practices from incineration to composting, the farm will release 22,486 pounds less CO2e each year than was released from the diesel fuel required to run the previous carcass incinerator.

This farmer made the decision to install a mortality compost facility based mostly on the cost of repairing and operating the existing carcass incinerator. Though reductions in greenhouse gas emissions were not a major factor in his decision because the CO2e emissions from mortality handling are small in comparison to other animal production practices such as manure storage and handling, animal housing and feed production, this case study is a good example of the unexpected benefits of a changing production practices. In the future, as society becomes more cognizant of these air emissions, reductions in greenhouse gas emissions may play a larger role in farmers’ decision making process.

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