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By Whitney Beadle
For MAA
Sit back and think of cow products for just a moment … visions of gooey cheese curds, dripping ice cream and mouthwatering hamburgers cooked just right. But, does renewable energy come to mind? It should. 
Agricultural operations have long provided a base for our nation’s economy and stomachs; however, they also serve as a vastly-untapped resource for continuous clean energy production, contribute to nutrient management plans, create organic products and overall further the sustainability of rural communities, when paired with anaerobic digestion systems. 
Similar to a cow’s stomach breaking down feed into energy to produce dairy and beef products, anaerobic digestion systems break down organic materials into energy products. 
Anaerobic digestion is a four-stage biological process that occurs naturally in the world around us. 
Essentially, very small bacteria called “micro-organisms” break down organic material (manure, food waste, yard waste and more) as it ferments in an environment without oxygen, creating two products:  biogas (a mixture of methane and carbon dioxide) and digestate (solid or liquid materials remaining after the process is complete).

Once biogas is produced and captured in a biodigester, it is typically combusted in an engine to make locally-produced electricity and heat. For example, manure from Rosendale Dairy in Fond du Lac County, Wis., is sent to an on-site biodigester. The biogas created in their system is directed to an engine, producing enough clean energy to provide the equivalent of electricity to 1,110 Wisconsin homes and heat another 1,030. 
Alternatively, biogas can be upgraded to renewable natural gas for use in the natural gas grid or as a vehicle fuel in the form of compressed natural gas. Compressed natural gas from anaerobic digestion typically has a lower carbon intensity, higher efficiency, and better energy yield when compared to other forms of vehicle fuel.
Since there is an endless production of manure and crop residues at agricultural operations, there is also constant feedstock to supply biodigesters — and therefore, also a potential for continuous renewable energy production in these communities. Biogas creation is uniquely dependable in the renewable energy realm because it occurs regardless of the weather conditions, can be stored and has a variety of end-use energy options.
The second product created from anaerobic digestion, digestate, also offers cost savings in the form of organic products. 
Raw digestate may be land applied as is for the fertilizer value, or further processed and upgraded to increase worth. 
Processing raw digestate can yield higher-value products such as compost, animal bedding, pelletized fertilizer, and recovered nutrients. 
Biodigesters play a critical role in an operation’s manure and nutrient management plan by capturing and controlling nutrients to prevent runoff. 
Through the anaerobic digestion process, nutrients are conserved and made more readily available to plants. Nutrients are also captured during the process, allowing for a more uniform application in nutrient deficient areas.   
All in all, the underlying environmental stewardship of agricultural operations can be increased with biodigester installations, along with the opportunity for cost savings and local energy creation. 
By using the manure and other organics that typically ferment in nature and release greenhouse gasses into the atmosphere, anaerobic digesters instead harness these gases, make energy from them and offset fossil fuel sources. Community sustainability benefits from reducing carbon footprints with biodigesters can be an important component to land and citizen health. 
The next time you see cows, consider just how much our society counts on them for tasty nutrition, as well as their ability to create clean energy and locally-produced fertilizer.  
Whitney Beadle is the channel marketing manager at BIOFerm Energy Systems. This column originally appeared in The Fond du Lac, Wis., Reporter.
 


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