Use of Solar Energy to Heat Anaerobic Digesters. Part I. Technical and Economic Feasibility Study. Part II. Economic Feasibility throughout the United States.

摘要

Two distinct,yet related studies were conducted to determine the technical and economic feasibility of using solar energy as the source of heat for the anaerobic digestion process. Retrofitting a solar energy collection and heat transfer system to a digester at Annapolis,Maryland was proven feasible in the first part of the study and the concept of using solar energy for digester heating throughout the United States,including Fairbanks,Alaska,was shown to be economically feasible in the second part of the study. The Part I study compared five (5) types of flat plate collectors and selected the cost effective design to supply approximately 90percent of the heat load to maintain digester operating temperatures of 32C to 38C. Three flat plate collectors of varying efficiencies were evaluated for use at numerous locations in the United States. The study showed that optimum-sized flat plate collectors can provide from 82to 97percent of the total annual digester heat,the higher percentages being applicable to areas of higher solar radiation. The Part II study developed specific guidelines for determining the optimum size and conceptual design for a solar heating system for any size sludge digester at any location.