Optimization of Biogas Production and Use

In its initial year of hauled waste operation, the City of Des Moines, Iowa, Wastewater Reclamation Authority (WRA) generated revenue in excess of 2.6 million by processing over 50 million gallons (189,000 cubic meters) of hauled waste and selling over 250 million cubic feet (946,000 cubic meters) of biogas to a neighboring industry. This was accomplished with digesters in need of new covers, non-functional mixing systems, and an undersized biogas conveyance system.With the potential for significantly increasing the volume of hauled wastes treated, the WRA recently initiated a process to improve digestion, biogas handling facilities and optimize biogas use. The first step in the process was to develop a Bioenergy Master Plan (BMP) to identify facility improvements and alternative methods for increasing biogas use and determine the economic value of the biogas for various uses. With the completion of the BMP in December of 2008, WRA initiated design of the preferred improvements. This paper and presentation will focus on the results of the BMP, as well as key aspects of the facility improvements.