Swine Farm Anaerobic Digestion Analysis Tool Available

Are you a swine farmer, or have a friend who raises pigs?  Are you interested in maybe adding an anaerobic digester to your operation to produce energy and control odors?  If so, you will be interested to know that Penn State Extension has released a new spreadsheet-based tool for analyzing swine farm anaerobic digesters that produce Renewable Natural Gas (RNG) that is delivered to the natural gas pipeline network. 

This tool is available on the Penn State Extension website, and is free for downloading and use.

The tool utilizes inputs about the farm's size and operating characteristics, and calculates the expected performance of the digester in terms of its economic productivity. This is a really important thing to know if you are considering a digester, because many factors can affect whether a digester will pay off or not. Some of the key inputs include:

• Amount of manure available
• Amount of cropland available for spreading nutrients
• Is there any land available to grow winter rye as a bioenergy feedstock?
• Is there any perennial grassland available to provide feedstock?

The estimated performance of the system is calculated, including two key values:

• Internal Rate of Return (IRR): numbers above 10% are considered favorable
• Net Present Value (NPV): numbers above zero are considered favorable

The spreadsheet-based tool takes into account the nutrients needed for crops, the fertilizer value of the digestate, the value of the Renewable Natural Gas, incentives, and credits. A total of 14 tabs calculate all of the necessary numbers related to cash flow, financing, nutrient balance, and crop budgets. If that seems a bit on the complicated side, don't fret! One of the tabs is titled "key inputs and outputs" and allows you to use the tool with a simplified set of input values, obtaining a summary of how the digester can be expected to perform. 

Developed by Ag Economist Bill Lazarus, the tool provides swine farmers and digester project developers with a new capability to look at how their planned project might perform. "Adding winter rye to manure is a new approach for Pennsylvania digesters" says Lazarus. "This may be a useful strategy for making these digesters big enough to be profitable, while incentivizing the growing of winter crops that help protect fields from erosion". 

The spreadsheet tool is the third in a series of digester economic analysis tools from Penn State Extension. The first two analyze

1. an on-farm dairy digester and
2. a dairy farmer's supplying manure to a nearby community digester. 

You can find them on the Penn State Extension website. The tools were developed as part of the USDA-funded C-Change Grass2Gas project, which has been working to find ways to improve anaerobic digestion economics while simultaneously benefitting the ecosystem.