A 10 Kilowatt, Rankine Cycle Agricultural Waste to Energy Conversion Module Utilizing Ultra Micro Turbo-Alternators

Current anaerobic digester systems are designed for capturing energy from waste from large heads of farm animals. GHD, Inc., a leading manufacturer of anaerobic digesters, has stated that a minimum dairy heard size for economical implementation of a biogas system as 800 cows. These require turbine or diesel generator sets of 100 Kilowatt size and larger, a limiting factor in economically scaling down of these systems. The need exists for a smaller waste to energy conversion approach for implementation for farms with herds less than 800 animals. The need also exists for a universal energy conversion system for other solid and liquid waste streams utilizing Syngas from pyrolytic reactors, or in some cases heat from directly combusting solid waste. These can be used for providing combined heat and power for rural homes or small farm plots typical of third world countries. Fluidic microControls. Inc. (FmC) has been developing a variety of technologies for micro energy systems, including ultra micro turbines, air bearings, and micromachined heat exchangers. FmC has most recently combined these into a 5 Kilowatt Rankine cycle waste heat recovery system for anon-farm electricity to nitrogen fertilizer manufacturing system, development initiated under partial funding from the USDA. The heart of this system is the novel FmC gas bearing turbo-alternator which may be cost-effectively utilized with a variety of off-the-shelf boiler, pump, heat exchanger, pyrolytic reactor, and digester technologies in a waste to energy conversion system sized for small farm biogas systems. The gas bearing turbo-alternator consists of a supersonic impulse turbine riding on air bearings, a permanent magnet alternator, and compressors which provides fluid power to the gas bearings and pump waste combustion products to follow-on treatment or storage sites. The patent-pending, fluidically damped gas bearing system has been successful demonstrated at over 300,000 RPM, and operates with much larger, contamination-tolerant flow passages and clearances than other air bearing types, while providing critical damping to the rotating mass system. Nozzles, bearing, turbines, and heat exchanger channels are manufactured using proprietary micromachining and laminate assembly processes which have been developed to make compact, cost-effective energy recovery components. The primary goal of this program is to apply this technology to provide an effective energy conversion module for small farm manure digestion systems, with an ultimate goal to provide a universal energy recovery module which can cost-effectively recover energy from a variety of waste streams, regardless of size.