Farms of the Future: Renewable Energy Production via Anaerobic Digestion

By Scott Romenesko, President of EnTech Solutions

Special to The Digest

The use of renewable energy in the agriculture industry is an exciting new frontier that – with the right partners – can bring environmental and economic benefits to farmers, surrounding communities and the renewable transportation fuel industry.

The utilization of livestock manure is nothing new. Historically, it is a tried-and-true farming method for improving soil quality to assist in crop growing. Using manure as a natural fertilizer also keeps carbon in the soil and out of the atmosphere, where it can form carbon dioxide, a greenhouse gas (GHG). This is critical, as agriculture makes up 11 percent of total greenhouse gas emissions. Add that to the transportation and electricity industries that make up 27 percent and 25 percent of GHG emissions, respectively, and we are looking at nearly two-thirds of the causes contributing to climate change.

Fortunately, these emissions can all be decreased by using technology that already exists.  Through the use of biodigesters, agricultural manure can be converted into renewable natural gas (RNG) and the remaining remnants into valuable materials including fertilizer, potable water and CO2.

Anaerobic digestion

According to the United States Environmental Protection Agency (EPA), an anaerobic digester is a system that uses organic waste to produce fertilizer and biogas, or renewable fuel. The process separates methane from the solids and liquids that make up manure while effectively keeping the odor from escaping into nearby communities. The methane captured at the top of the digester containers can then be used to create RNG.

How do anaerobic digesters work and how do they benefit multiple industries?

Animal manure is deposited into anaerobic digesters. When maintained at a temperature of 100 degrees Fahrenheit, digesters create an environment where microbes thrive and consume the volatile solids in the manure while producing methane gas. The extracted methane gas can be repurposed in a variety of ways. It has traditionally been used to produce electricity through combustible generator engines, but it can also be used to produce clean RNG fuel for vehicles.

It can then be injected into a pipeline and used in the transportation industry for cleaner fuel-burning vehicles. This is especially important for vehicle fleets in states like California, Oregon, Washington and New York which have federal laws and regulations that reward corporations for decreasing emissions to promote cleaner air. Using RNG reduces pollution and enables organizations within the transportation industry to meet those requirements.

The future is now in Middleton, Wisconsin

When we say, “farms of the future,” we really mean right now. This digester technology is being used at a facility in Middleton, Wisconsin, located just outside of the state’s capital, and is a notable example of what the agriculture industry can achieve.

EnTech Solutions, a clean energy provider, and Northern Biogas, a digester and RNG development company, partnered with local farmers and Dane County to repurpose a digester that had formerly been producing electricity. The facility in Middleton features three anaerobic biodigesters that break down manure brought in from four local dairy farms.

In 2021, over 27 million gallons of manure were processed by the facility and more than 57,000 pounds of phosphorous were removed from the Yahara Watershed, a natural drainage system in southern Wisconsin. The partnership also features Aqua Innovations’ nutrient concentration system and U.S. Gain as the off-taker of the RNG.

This self-sustaining network benefits the farmers who can manage their animal waste, prevent the release of methane into the atmosphere and receive the resulting nutrient-dense materials for their fertilizer and bedding. It benefits the county and community by reducing the phosphorous runoff to nearby streams and lakes. And it benefits the renewable transportation fuel industry with the RNG created by the extracted methane.

Drive profitability within farms of the future

Beyond these benefits, the Middleton facility was also strategically designed to run off of multiple forms of renewable energy. EnTech Solutions powers the Middleton facility using distributed energy in the form of a microgrid that is powered by solar panels and battery storage.

As a result, the solar generates more than 2.8 MW of clean energy, which is the equivalent of powering more than 400 homes. This effectively reduces emissions by more than 13,500 metric tons per year of carbon dioxide equivalent – which is the equivalent of removing nearly 34 million miles driven by cars. By producing and utilizing renewable energy at the facility through microgrid technology, the RNG is cleaner and more valuable.

The more layers of renewable energy that are integrated into the creation of RNG, the greater the impact on reducing greenhouse gases. For example, if RNG is transported using electric vehicle fleets powered by renewable electricity, that would further reduce the negative impact on the environment.

When it comes to renewable energy, there are a lot of moving parts. It can be difficult to see the big picture and understand how everything fits together. But when you do, the possibilities are endless.

The long-term benefits continue to reach farmers as well. Transforming agriculture operations preserves farm families’ way of life while solving many of the problems facing them. Advanced anaerobic digesters open the door to more revenue from crops and dairy and an increased output of manure which is turned into RNG, fertilizer and bedding, creating an easier path to farm growth.

The anaerobic biodigester facility in Middleton, Wisconsin is a prime example of what the farms of the future can look like. Using multiple forms of renewable energy, even at the scale of an industrial facility, is a self-sustaining model that can be replicated in communities throughout the country.

Cows produce manure; that is nothing new. But now we have the technology behind anaerobic digester facilities, nutrient concentration systems and renewable energy sources to run clean carbon-neutral or even carbon-negative operations. These advanced facilities allow farmers to function as they always have but ensure they are being more environmentally conscious.  We say they are the farms of the future. But in reality, that future is now.