ASERTTI Digester Performance Partnership

Phase Two Digester Program: Pilot Performance and Cost Database for Anaerobic Digester Systems for Livestock Manures

Through a grant from the Blue Moon Fund, ASERTTI embarked on Phase Two of the digester program and completed a study titled "Pilot Performance and Cost Database for Anaerobic Digestion Systems for Livestock Manures" to better understand how the protocol was being used, and to find ways to increase the volume and quality of performance data available to the public. The Energy Center of Wisconsin, an ASERTTI member, was the lead on this study.   

Purpose: The purpose of Phase Two of the digester program work was to help overcome the challenges of collecting new data and analyzing existing ASERTTI/AgSTAR protocol driven data, promote greater levels of testing, create recommendations for digester operation improvement, and  provide public access to the protocol information.

Background: Several years ago, ASERTTI members determined that the relatively high failure rates among anaerobic digesters in agricultural settings were an impediment to realizing the potential value of livestock manures as a renewable source of energy as well as the associated environmental, energy efficiency, and energy cost benefits.   Thus, ASERTTI undertook the first phase of a digester protocol program as a means to identify successful design, feedstock, and operation combinations and promote the growth of this important technology.  Through Phase One funding, ASERTTI, in partnership with USDA Rural Development and EPA's AgStar Program, developed a detailed set of protocols to assess digester options, designs, and performance.  However, it quickly became evident that the challenges to encourage testing and analysis were considerable.  Phase Two of the digester program was developed to address the significant outreach required for investment and the considerable analytical time necessary to fully understand the data. 

Results: An MS Access database populated with data on installed farm anaerobic digester systems and pre-made reports summarizing performance data for Web posting were developed. The final report for the ASERTTI project, Pilot Performance and Cost Database for Anaerobic Digestion Systems for Livestock Manures, describes the results from the examination of the early attempts at using the protocol with a primary focus on the  means by which barriers could be removed or reduced to expand the protocol's  use and increase its utility.  Attempts to use the protocol have been sparse, and the successful gathering and reporting of protocol adherent data even rarer. This is due to a number of factors that have deterred researchers from using the protocol, and others that prevented successful completion of monitoring efforts once the decision to use the protocol was made. Some of these issues and complications are further discussed in the Findings section of this report. 

Next Steps:  The ASERTTI/USDA Rural Development/AgSTAR protocol serves an important function in providing a standard means of characterizing and evaluating farm-based anaerobic digester systems as well as monitoring their performance. The early applications of the protocol described in this report provide valuable information on barriers to its use. The new international protocol will take an important step in encouraging more widespread use of standardized characterizations by offering tiered options of varying cost rather than "all-or-nothing" adherence. It appears, however, that funding for full protocol use will continue to be an issue, and that any efforts to develop more farm system data using the protocol will need to be funded by some entity other than the farm, the digester designer, or the involved utility. None of these groups alone will likely be motivated enough to bear the expense.