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Why Do We Need Anaerobic Digesters Running on Farms?

If we can create a vibrant anaerobic digestion industry here in the U.K., we will reach our goals in economics and the environment. ~ Jacob Rothschild

Poop to Fuel

Driving by a dairy, a stockyard, or a pig farm, I first notice my olfactory senses going off! Then, I turn my head toward the manure aerating along the roadway, wondering about the census of every animal we use for protein, and thank a farmer. I thank farmers for staying home to care for the herd and manage animal health and manure. Yes, I thank every farmer for managing manure because most of us, including myself, view waste management as an untouchable discussion. The undeniable fact is that we all poop and pee, and it does need to go somewhere. Why not make power out of the methane gas from the waste we generate? What if Power Purchase Agreements (PPAs) don’t pencil? 

We love French butter, heavy creams, Picana or Ribeye steaks, and pork tenderloin. Some might ask what this article title means or why I write about manure management and responsible food waste dumping. Sometimes, I ask myself why I feel dedicated to the “Back of the House.” We have 9 billion people to feed, and farmers are doing their best to produce those delicious proteins for us in the safest manner possible. On the back of The Food Safety & Modernization Act (FSMA), producers have always dealt with waste by-products due to producing the food we eat. But it's not just about laying pipes and building manure pits to spec. Because for every 100 dairy cows, farmers have to manage 1 million gallons of poop. 

Farmers use manure power to heat their homes, run hot water for showers, create revenue from food waste tipping fees, and build capital from Carbon Credits in the open market. During the tough times, when commodity prices are down and inflation is rising, our farmers might have a fighting chance to stay in business. 

Anaerobic Digester Systems Make Power

It’s about taking that waste, producing methane for electricity and hot water, and using the gas to power farms and communities around us, making methane, cranking up the biogas engine, pushing power units, or wattage to the Three-Phase line out at the road, which offers our farmers a way to stay in business for the long run. As livestock production laws change, the ability to produce animal products becomes more and more cost-prohibitive. That, in turn, pushes the price per pound higher for the consumer. Handling manure using an Anaerobic Digester removes the noxious odors, improves the farm’s ecosystem, and increases yield for energy crop growers. 

Manure and wastewater need to be collected and held in a pit lined with High-Density Polyethylene (HDPE). Essentially, the pit is lined with an insulated, heavy-duty plastic liner with a thickness of up to five feet deep, and the lagoon itself is standardized at 25 feet in depth.  Farmers have to decide, with the help of geological engineers, which type of lagoon is best suited for the local soil makeup.  Once the manure is lagoon-ready, the farmer builds out a plan to cover it with HDPE, heating that poop to an ambient temperature of 95°F to 120°F range. system. 

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Hydrogen Sulfide Scrubbers 

Once the lagoon heats, the process of taking the waste and producing biogas begins. The biogas heats and gets filtered through a hydrogen sulfide scrubber (H2S), a tower where the biogas is drawn upward, flowing through a reactor that captures impurities and cleans the gas. That gas is run through a biogas generator in an engine room just off the barn. The generator converts the gas into electricity throughout the farm to power lights, heat, and the boiler. Most vessels stand about 20 feet tall, are constructed of steel or fiberglass, and have a 2-4” thick insulation.  Oxygen injectors and Media are installed to capture the waste byproduct of producing methane.  This system is engineered to be between the Digester and the generator system. 

Carbon Sequestration

Adding Food Waste To Biogas

Food waste products are derived from manufacturing and large commissaries, commercial kitchens, and restaurants. The Fats, Oils, and Grease (FOG) are placed in a holding tank, where waste trucks pick up and deliver to local digesters, tipping fees are paid, and the trucking companies offload the waste into what is called an Influent holding tank then pumped into the Digester and heated to increase biogas production. Once processed in the Digester, residual waste is left, free of any bacteria, called digestate.

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Carbon Credits 

Farmers work hard to manage livestock, implementing regenerative practices to improve soil, like adding effluent to increase Nitrogen.  The Digesters they work to implement must be Department of Energy-approved, addressing a calculated amount of carbon dioxide. Carbon sequestration is calculated per unit; most carbon credit companies use proprietary software to evaluate the removal of atmospheric carbon dioxide by the project. 

Carbon Trading

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