The farmers use the electricity generated from burning methane to power their farms, heat their homes, and if there’s any extra, sell it back to the power company.
The U.S. Department of Agriculture reports that about 37,000 dairy farms are in operation. About 200 of those farms are harnessing biogas from manure, according to the EPA. Other sources of biogas include hog and poultry farms, and wastewater treatment plants. The Environmental and Energy Study Institute reported in 2017 that the United States had 2,200 biogas systems, a fraction of the total number of potential systems the country could have.
A noble investment
Noblehurst Farms was an early adopter, installing its first anaerobic digester in the early 2000s. It was destroyed in a fire, and they replaced it in 2014.
“The digester was an example of something we could invest in on the farm that would help keep us cost-competitive, diversify our farm, and address climate change,” Noble says.
The current dome-shaped building holds more than 1 million gallons of liquid poop, which is separated from the solids. The plastic roof traps the gas naturally produced as bacteria digest the manure.
To supplement the 40,000 gallons of manure his cows excrete every day, Noble launched Natural Upcycling, a food scrap collection business. Food scraps also release methane when broken down.
The combination of manure and food scraps processed in Noblehurst’s digester reduces methane by an amount equivalent to reducing carbon dioxide emissions by an estimated 409 tons per month. That’s like taking 1,000 cars off the road annually, according to AgSTAR, a federal program that promotes biogas recovery from farms.
The resulting mixture of food waste and cow manure produces 200 to 250 cubic meters of biogas. That’s enough biogas to fuel a 500-kilowatt (kW) generator.
The 500-kW generator keeps the digester heated, and powers the farm, a neighboring creamery, and a cheese-making facility. The system saves the farm about $100,000 in electricity costs annually. As an added bonus, the digestion process removes the potent smell associated with manure.
In 2016, California passed a law requiring dairy farms to cut methane production by 40% by 2030. Methane digesters have helped farmers already achieve a 25% reduction in three years, according to Mitloehner. A patchwork of other state regulations also aims to cut methane emissions from various sources, including agriculture.
Many farmers are motivated by more than new laws to help with climate control. They are often called the original environmentalists for spreading manure from their own livestock to fertilize their fields, as opposed to buying synthetic or mined fertilizers, which require additional energy and resources to produce and transport. Consistent with that tradition of practical solutions, farms across the country, in addition to building anaerobic digesters, are implementing other practices to address climate change.
Noble notes that practices that help the planet also help farmers, which could allow generations-old operations like his to carry on well into the future.