It’s not something we talk about in polite company, but waste – human or animal – is not really waste. It’s a resource that, among other things, can be used to generate power, and help make farms – and homes – much more independent of traditional power companies. Think ‘biogas’. Think ‘circular economy’. Think ‘opportunity’ rather than ‘problem’.
I was reminded of this yet again when I was reading a recent IPS story from Argentina, about the Monje Agricultural and Livestock Cooperative, which operates a pig farm of about 200 sows that is located in the northeastern province of Santa Fe. Two hundred pigs produce a lot of manure, which used to be collected in large open ponds that emitted methane – not to mention objectionable smells.
Then, in 2018, the cooperative installed a biodigester, which treats the pig farm effluent along with other organic farm waste. Like nature does, the biodigester converts the organic matter into energy using bacteria that carry out an anaerobic degradation process. Now the waste powers an electric generator, which reduces the need for oil, and a grain dryer that is used when the harvest is wet. The byproduct, biofertilizers, are used on the 35-hectare fields.
Some larger agribusiness companies also have found value in biogas. Adecoagro, which produces milk, grains, rice, sugar and ethanol in Argentina and also does businesses in Brazil and Uruguay, now describes itself as a “producer of food and renewable energy under a sustainable model.” In 2004, it began looking at how it might use the manure from its 12,000 dairy cows on four dairy farms in Cristophersen, Santa Fe, for more than just fertilizer on their fields.
Since 2017, Adecoagro has been contributing electricity to the national grid, having invested $6 million in a biodigester. “We have 1.4 MW in installed power. We could cover the energy needs of a town of between 500 and 1,000 residents,” Lisandro Ferrer, head of Industrial Projects, told IPS. “The biodigester is fed with 200 tons of cow manure per day, which is sent to three 5,000-cubic-metre concrete tanks. The way we see it is the cows transform the corn they eat into milk, and what is left over we transform into biogas to generate electricity,” he explained.
Having read complaints from local people in some US communities about the smell from open manure ponds, I wondered if US farmers had thought of the biogas idea – and was surprised to learn how many have. Some of the stories:
Reinford Farms, in Pennsylvania, has been converting manure biogas to electricity since 2008. They sell the electricity back to the grid. The digester also reduces energy costs on-farm. Heat is used to dry corn, warm their house and shop, heat all of the farm’s hot water, and pasteurize calf milk.
They originally installed the biodigester to reduce odors when they applied manure to the fields. “It was not until after we installed the digester that we realized the other benefits, including revenue from selling back electricity, tipping fees and money savings from capturing the waste heat for on-farm use.”
Also in Pennsylvania, Brubaker Farm’s digester produces more than 4 megawatts of electricity a day – equivalent to the amount used by 150 to 200 homes. Some of the electricity is used on the farm; the rest is sold to the local power company, which pays a premium for the renewable energy generated by the digester.
Working with NativeEnergy, a Vermont-based energy broker that specializes in farmer-owned, community-based renewable energy projects, Brubaker Farm has sold carbon credits based on methane emission reductions achieved from the anaerobic digester. The farm, the 2011 Innovative Dairy Farm of the Year, also installed solar panels on the roofs of their barns and has also sold solar RECs for that energy.
In New York, the seventh-generation Noblehurst Farms uses manure from its 1,800 cows and approximately 500 tons of food waste per month from local universities, schools, restaurants, and Wegmans Food Markets to generate renewable energy that powers the farm and a nearby creamery. As a byproduct, it gets high quality liquid fertilizer it uses on the farm.
“Digesters are great for the environment and great for power reliability. The sun doesn’t always shine and the wind doesn’t always blow, but we can keep this digester and program going day and night,” says Chris Noble, vice president of Noblehurst Farms
As an Argentinian farmer says: “Farmers are beginning to realise that livestock production effluent is not a waste product but a raw material that can generate value, and that an environmental problem can become a profitable solution.”