Design and Analysis of a Biogas Digester for a Net-zero Energy Community in Southwestern Ontario

This research involves the technical design, economic, and environmental analysis of using anaerobic digestion to supply the heating fuel needs of a 2000 home community. To understand the technical challenges involved in biogas production for a community, a technical model (AMD1) was utilized as the basis of modeling development centered on methane production and feed material inhibition. Through analysis, it was determined that a key component of selecting whether to run year-round vs. partial season was in the heat loss versus increased heat generation. From both a capital and operating cost point of view, the net gas production in shortened seasons could not account for the increased production intensity needed to meet the overall goal. Beyond the findings regarding operational efficiency, the fixed cost of the project was identified as under $2100 per home of initial investment and a gas production cost of $0.35/m(3) of gas versus the market rate of $0.33/m(3) of non-renewable sourced gas. Beyond the carbon neutral nature of the biogas produced, the decentralized production system of anaerobic digestion also allows for a 23% decrease in net CO2 emissions compared to conventional natural gas systems, yielding a greater environmental benefit.