PR - Economic Analysis Of Anerobic Co-digestion Using Dairy Manure And Byproduct Feedstocks

There is increasing interest in the United States to expand the use of anaerobic digestion (AD) as a means to generate renewable energy and reduce greenhouse gas emissions from dairy operations. Economic feasibility is the primary constraint facing farmers and investors considering an AD capital investment. The purpose of this paper is to develop an economic optimization model of an AD system using co-digestion of dairy manure and byproduct feedstocks. This model uses a daily time step to specifically model the operating parameters and AD technical design and capacity constraints. The end of system digestate is applied to farm land subject to agronomic application rates and timings. The model is applied to an existing AD system producing electricity in Washington State. The paper reports the technical aspects and operating parameters of the modeled AD system. The economic results conclude a positive economic feasibility but a low rate of return for the modeled system. The conclusions suggest evaluate alternative AD design options and AD evaluation methods to increase the economic feasibility of AD systems for dairies.

Keywords: anaerobic digestion, co-digestion, linear programming, economic feasibility