Based on the information gathered the team was able to determine boiler burn rate (202-313 kBTU/hr), gas quality (60% CH4), digester system efficiency (55%), digester system reliability & availability (82% & 95% respectively), and boiler combustion efficiency (70-90%). The team also identified possible causes of foaming which has been an issue for the digester operation. Several lessons learned have also been documented and areas for further study are proposed.
Farm Schematic Showing Freund's Farm Digester Integration.
This project was intended to provide Freund’s Farm, Inc. with increased understanding regarding the current performance of the methane digester installed on their farm in order to enhance the digester’s performance.
Freund’s Farm, Inc. is a 230 cow dairy in Northwest CT that has been operating the digester for 9 years with significant labor and maintenance burden. The digester is considered an integral part of the farm’s nutrient management plan and also provides thermal energy to farm buildings.
Additionally, the Freunds have embarked on the development of an innovative, value-added, off-farm product which could incorporate several digester outputs. This product family currently includes planting pots (“COWpots”) and weed barrier paper (“COWpaper”) which can be made from fibers, nutrients, and heat extracted from the digester.
The work described in this report has provided a database of digester knowledge that should support the consistent, reliable, repeatable performance of the digester.