Feasibility Assessment of Medium-Scale Anaerobic Digesters for Conversion of Brewery and Dairy Farm Waste Streams

Abstract

Anaerobic digestion (AD) involves the conversion of organic matter in the absence of oxygen to produce methane (CH4)-rich bio-gas that can be used for heating, vehicle fuel, or for generating electricity. The evolution of AD systems has historically followed two distinct paths: small residential-scale systems in the developing world to provide modest bio-gas resources for heating and cooking, and multi-million dollar facilities in the developed world for grid electricity production. However, there is a strong need to explore the possibility of applying AD technology in the medium-scale range (on the order of 100s of kW to 1 MW), which would be relevant to many farm installations and food processing plants that have significant organic waste resources. In this paper, technical and economic feasibility assessments have been conducted of two specific applications important to New York State: treatment of dairy farm resources in the Upstate region, and treatment of brewery and distillery waste in the New York City region where significant waste disposal barriers exist. In each case, a comprehensive analysis was first conducted of the available waste resources. Then, using data available in the open literature, an estimate of the total amount of renewable bio-gas that can be produced (bio-methane potential, BMP) was developed and used to compute the achievable size of a centralized AD system. For both the farm and brewery applications, it was determined that energy systems based on anaerobic digestion can be economically and environmentally viable, provided that ample organic resources are available, as well as incentives to offset the initial capital investment.