Software to Encourage Dairy Manure-Based Anaerobic Digester and Greenhouse Synergies

Abstract. As a means to identify ways to specifically improve the economics of dairy manure-based anaerobic digestion systems (ADS), controlled environment agriculture systems, and overall sustainability for both dairy farms and greenhouse growers, Cornell‘s PRO-DAIRY Program — Environmental Systems Group undertook a USDA Hatch, Smith-Lever funded project with the overall goal to quantify the synergies of surplus heat and electricity produced by manure-based anaerobic digesters to supply the heat and electrical needs of commercial greenhouses. As a part of the three-year project, data was collected over its duration from three commercial dairy farms with operating anaerobic digesters (two in NY and one in ME), and from two smaller commercial greenhouses (NY and Ontario, Canada). The collected data, other data, and engineering principles were used to develop and validate the multiple computer models with a purpose of predicting surplus heat and electricity from ADS, and the associated demands of commercial greenhouses. The computer models were then developed into a user-friendly software package that we call the Cornell Digester Greenhouse Simulation Software (CDGSS).

For this paper, CDGSS was used to determine the maximum sizes of commercial greenhouses that could use the waste heat and surplus electricity from dairy farms of varying size (500 to 3,000 lactating cow equivalents) with varying types and quantities of co-digestion material (imported off-farm generated organic wastes (which can significantly increase biogas production). For the range of the analysis performed, results showed that the combined annual economic value of the available (surplus) electricity and thermal heat ranged from $11,600 to $235,000/yr based on an electrical and thermal energy price of $0.10 per kWhr and $10 per MMBtu.