Compost Waste Heat to Power Organic Rankine Cycle Design and Analysis

Abstract This paper presents a feasibility study of a hybrid compost waste heat to power/Concentrating Solar Panel (CSP) green energy Organic Rankine Cycle (ORC). The power plant is baselined to operate with a duty of 24/7 on compost waste heat and utilize solar thermal energy to boost power output during the day. This paper discusses the design of the power plant, the design of a compost driven heat exchanger/boiler, compost pile thermal analysis, CSP analysis, and simulated power plant output analysis The selection of isobutane as ORC working fluid is justified herein. A Levelized Cost of Energy (LCOE) analysis was performed to ensure that the energy produced by this hybrid power plant would come at a reasonable and competitive cost. The results herein show that the hybrid power plant affords an LCOE of 4 ¢/kWh for compost operation alone and an LCOE of 10.7 ¢/kWh for compost and CSP solar energy operation. The hybrid compost/ORC power plant presented herein affords an average energy conversion efficiency of 4.3%. Centric to the operation of the compost waste heat to power plant presented herein is the correct design and selection of the heat exchanger which interfaces the compost waste heat stream to the isobutane ORC. The design and analysis of this heat exchanger as well as commercially off-the-shelf hardware to meet the specifications is given in detail herein