Optimization of agricultural anaerobic co-digestion with diverse feedstocks

View the project final report

Commodities

Practices

• Animal Production: manure management
• Education and Training: extension
• Energy: anaerobic digestion

Anaerobic digestion (AD) allows farmers to generate renewable natural gas (methane) from manure, earn carbon credits by reducing greenhouse gas emissions, and sustainably treat manure and other organic waste to reduce their environmental impact. Agricultural anaerobic digesters can increase production of renewable natural gas and profit by co-digesting agro-industrial feedstocks in addition to manure; however, the selection process for the type and amount of each feedstock is challenging. Previous researchers have shown that biomethane potential (BMP) tests on these feedstocks can predict methane production in full-scale digesters, but many anaerobic digestion operators do not have the knowledge or resources make this evaluation. In addition, BMP testing can be time-consuming and expensive, particularly if a third-party must be involved. There is a critical knowledge gap among digester operators in evaluating potential co-feedstocks and among scientists in performing this evaluation rapidly and efficiently. Our solution is to both increase AD operator knowledge of co-digestion and develop techniques to predict feedstock performance in full-scale farm AD.

The primary goal of this project is to increase adoption of anaerobic co-digestion in the North Central Region through 1) reducing risk of entry for farmers through by predicting co-digestion performance of feedstocks commonly available for agricultural digesters and 2) training farmers about co-digestion. Partnering with local farming company Bio Town Ag in Indiana and other farmers, I will work with faculty experts at Purdue University to study eight feedstocks used used in agricultural digesters. In addition, I will develop a predictive model to inform AD operators as they transition to or expand the co-digestion on their own farms. From this research, I will publish two academic journal articles and an extension article, as well as use the results for my dissertation and present at an academic conference. A workshop training will be held on-site at Bio Town Ag for farmers interested in adopting or optimizing their use of co-digestion. In addition, we will conduct a workshop at the Waste to Worth Conference, reaching additional farmers and extension specialists. We will also participate in a national co-digestion webinar hosted by EPA’s AgSTAR program. The extension article, workshops, and webinar will spread awareness of the benefits of co-digestion for agricultural digesters, enabling farmers to both increase profitability and improve environmental stewardship through increased generation of renewable energy, reduced farm carbon footprint, and improved air quality.

Learning Outcomes:

• Outcome 1: Farmers will understand the economic value of several possible agro-industrial co-digestion feedstocks for use in their farm digesters. This will be measured by the number of feedstocks (target: eight) tested for their co-digestion methane yield and digestion rate and correlated to simple predictors that can be a first indicator of possible value. The results will be important for Bio Town Ag and other farmers considering co-digestion when selecting future feedstocks.
• Outcome 2: I will develop a model that will predict how to improve yield from existing digesters using experimental results of laboratory tests. The Bio Town Ag farm and other agricultural AD operators will learn how to apply the predictive model for full-scale co-digestion on their farms.
• Outcome 3: Farmers and extension specialists will be able to evaluate to evaluate possible co-digestion substrates on-site through an extension publication, a training workshop located at Bio Town Ag, a workshop in the Waste to Worth Conference in Ohio, and a national webinar hosted by EPA AgSTAR. These workshops will spread knowledge to agricultural AD operators in the North Central Region and provide a collaborative forum for networking with other digester operators.

Action Outcomes:

• Outcome 1: Bio Town Ag and other livestock farmers will apply the research results to optimize digester feeding strategy, increase renewable natural gas production, and improve sustainability.
• Outcome 2: More farmers using anaerobic digestion will adopt co-digestion (target: 6% increase in the North Central Region, or two additional farms).