Feasibility Study for the City of Twin Falls Sewage Hydroelectric Project in Twin Falls County, Idaho

摘要

The City of Twin Falls, Idaho authorized J-U-B Engineers, Inc., to assess the feasibility of installing a small hydropower plant on the discharge of the City's Grandview sewage trunk line. The concept of developing hydropower from sewage flow is novel and may have applications in other areas of the nation if its technical feasibility can be established. No conventional turbine would be suitable in this application without extensively screening the influent. Therefore, finding a turbine which would work satisfactorily, was one of the major aspects of the study. A solution to this problem was found in a staged, non-clog, hydraulic turbine manufactured by Cornell Pump Co. A preliminary design configuration is presented using these turbines. The economical feasibility of the project depends on future sewage flows from Idaho Frozen Foods Company, a large contributor to the present Twin Falls sewage flows. The yearly revenue, would decrease by about one-third, if Idaho Frozen Foods disconnects from the City's sewage system. Therefore, the project is less feasible, economically, without the flow contributed by Idaho Frozen Foods. The cost of energy production is 47 mils per kilowatt-hour (kWh) with this flow, and about 60 mils/kWh without this flow. At the higher flow rate (5 cfs) the total capital investment is estimated to be $270,200 or approximately $2250 per installed kW capacity. Estimated annual energy production at 5.0 cfs is 440,650 kWh with a subsequent first year annual revenue of $59,460. Power could be put on line within nine months of the time the Twin Falls City Council makes a decision to develop the project.