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Sunny Knoll Farm

Location Perry, New York
Project Type Farm Scale
Animal Type Dairy
Population Feeding Digester 1,800
Baseline System Storage Lagoon
Digester Type Horizontal Plug Flow
System Designer RCM International, LLC
Biogas Generation 111,400 ft3/day
Biogas Use Cogeneration
Generating Capacity 230 kW
Receiving Utility New York State Electric and Gas (NYSEG)

Farm Bill Funded Project


Photo of completed plug flow digester

RCM International, LLC

Sunny Knoll's primary reason for installing a digester was to offset farm electrical costs. Approximately 43,000 gallons of manure is scraped from three freestall barns each day. The manure flows by gravity into a below ground mixing tank where it is stirred and then pumped directly into the digester.

In 2006, the farm began operating a below-grade, plug flow digester with a flexible cover. The system operates at a temperature of approximately 100°F and has a hydraulic retention time of about 18 days. Biogas is pressurized using an electric blower prior to entering a 230 kW Caterpillar G379 engine-generator set. Generated electricity is used on the farm and surplus is sold to New York State Electric & Gas. Excess biogas is burned by a gravity flare.

Waste heat from the engine is recovered as hot water and used for domestic hot water, space heating, and heating the digester. Excess heat is sent into the atmosphere through an external radiator.

Sunny Knoll's digester project includes the following benefits:

  • Odor reduction
  • Electrical savings (approximately $14,000/month)
  • Reduced risk of run-off and nutrient leaching

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