Research Project Summary Information
Feasibility Study to Determine the Optimum Use of Digester Biogas at Coolbrands Dairy(ST9432-1)
North Lawrence Dairy, Inc.
North Lawrence Dairy is a cheese manufacturer with an anaerobic digester currently under construction. The dairy originally contemplated using the biogas to replace fuel oil used to make steam, but other uses, such as addressing peak power demands, could save more money for the plant.
North Lawrence Dairy partnered with Clarkson University to determine the optimum heat and power use from biogas at the dairy. Researchers: 1) determined current and past heat and power needs at the plant; 2) related power needs to seasons and manufacturing cycles; 3) determined current and projected electricity and fuel costs; 4) evaluated different technologies suitable for biogas, such as engines, fuel cells, and microturbines, including technologies that allow for dynamic power production; 5) further developed a tool that assesses the economic value of these technologies; 6) addressed peak demand costs and cold climate issues; and, 7) used the tool to help reach a decision at the dairy about technology choice.
At a minimum, the digester would replace 250,000 gallons of fuel oil, or 25% of the fuel oil used at the plant. A better system could create even more value for the dairy.
The plant’s current digester was designed to use the biogas to generate heat. Given the current pricing structure for fuel oil and electricity as well as multiple and dynamic energy demands, this was unlikely to be the most economical solution. The goal therefore, was to determine the optimum combined heat/power (CHP) use of the biogas for a given operating condition. Current and past heat and power needs of the plant were examined, particularly those related to seasons and manufacturing cycles. Using current and projected electricity and oil prices, generation of CHP from the biogas was investigated for internal combustion engine generators, fuel cells and microturbines. A comprehensive tool was developed that allows for economic assessment of biogas technologies and identification of cost-effective pricing structures. Results showed the most economical choice at current energy prices and production levels was to use biogas to offset #2 fuel oil for heat generation. Increasing electricity cost by approximately 3%, however, would favor installation of CHP microturbines. Fuel cells, while exhibiting higher thermodynamic efficiencies, are currently not cost competitive. The model further predicts electricity and heat consumptions as a function of manufactured product at 15 minute intervals. It could be a used by a plant engineer to minimize energy consumption through scheduling each production line.
North Lawrence Dairy, Inc.
f/k/a CoolBrands Dairy Inc. 22 County Route 52
North Lawrence, NY 12967
NYSERDA Contact Information
R&D - Environment & Energy Res