Economic Feasibility Study of Colorado Anaerobic Digester Projects ...

corrosiveness of biogas on electrical generators resulted in a “vicious cycle” of generator
repair costs, while electricity costs continued during engine shut-down time.
Mr. Barka stated that the primary motivation for maintaining the AD system was to remain
within compliance with state air emissions regulation standards. In 2007-2008, the electrical
generator was converted from biogas to natural gas. This involved considerable expense,
although data were not available for costs incurred. Waste heat is used to maintain the
digester and the farm flares off the remainder of the gas. The company is not interested in
returning to electrical generation, but acknowledges benefits to odor control and future
potential for energy independence.
Up to this point, Christensen Farms has been focused on stabilizing the AD system function.
Mr. Barka provided the following insights into cost containment and areas of future revenue
generation:
• In fall 2008, approximately $180,000 was spent to replace the system’s cover.
• The site employs a maintenance worker (at approximately $15-$20/hr.) who spends
approximately 20-25 hours per week to ensure accurate digester operation.
• The company qualifies for and eventually intends to obtain carbon credits.
• The company is not currently using the effluent, but is considering this to be a future
opportunity.
Additional contact information:
Christensen Farms Midwest, LLC: 23971 County Road 10 Sleepy Eye, MN 56085
Main point of contact: Mr. Adam Barka (Environmental Resource Manager—MN):
507-794-5310 ABarka@christensenfarms.com
Mr. Dave Nord, Operations Maintenance Supervisor
Lamar, Colorado contact: Mr. Kritch Stokey, Maintenance Specialist: 719-940-0087
5.5 City of Greeley. Bruce Biggi, the Economic Development Manager for the City of
Greeley, is directing a large-scale effort to develop a “Greeley Clean Energy Park” on land
within the Western Sugar Tax Increment Financing District. Biggi requested—and
received—NEED grant funds to conduct a Phase 1 engineering and economic feasibility
analysis for a co-digestion project. The City of Greeley contracted with the technology
provider Symbios and Stewart Environmental Consultants to conduct the first phase of the
study. The economic feasibility study began April 1 and the first draft of the report is
expected by September 29. The final report will be due to the City of Greeley and GEO by
October 30.
Mr. Biggi (City of Greeley), Mr. Justin Bzdek (Symbios), Mr. Rick Jones (Symbios), and Mr.
Forbes Guthrie (Stewart Environmental Consultants) attended an in-person meeting in the
Symbois Ft. Collins office. Other discussions with Mr. Biggi pertaining to the project took
Economic Feasibility Study of Colorado Anaerobic Digester Projects
Prepared by Dr. Catherine Keske, Colorado State University
August 2009
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