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

EPA Contract Number: EPD13045
Title: A 10-Kilowatt, Rankine Cycle, Waste-to-Energy Conversion Module Utilizing Ultra Micro Turbo-Alternators
Investigators: Frederick, Gary
Small Business: Fluidic microControls, Inc
EPA Contact: Manager, SBIR Program
Phase: II
Project Period: July 29, 2013 through July 28, 2015
Project Amount: $300,000
RFA: Small Business Innovation Research (SBIR) - Phase II (2013) Recipients Lists
Research Category: Small Business Innovation Research (SBIR) , SBIR - Sustainabile Utilization of Biomass


In 2011, there were 60,000 dairy farms in the United States. Of these, 56,600 had herds of fewer than 500 animals. Currently, manure digester installations are only considered economical for herds of at least 500 animals. These require turbine or diesel generator sets of 100 kilowatt size and larger. The need exists for a smaller waste-to-energy conversion approach for implementation on small farms where methane is typically released, unburned and unutilized, to the environment. This project evaluates the feasibility of an electrical-power-generating system based on a steam Rankine cycle, sized and designed to burn untreated digester gas from small animal herds. The system uses a residence-sized steam boiler, modified to produce higher operating temperatures and pressures to improve cycle efficiency. The steam from the boiler powers a unique turbo-alternator spinning on fluidically-damped gas bearings, also energized by system steam. The analyses and studies conducted in Phase I showed feasibility of the steam Rankine system and fluidic bearing turbo-alternator approach. Key features that were analyzed and/or demonstrated are as follows:

  • Rankine cycle system may be scaled to herds of only 25 cows.
  • A representative turbine rotor is capable of high-speed operation when spinning on fluidically-damped gas bearings.
  • Fluidic bearing operation was demonstrated using system steam.
  • A closed system with fluidic bearings is capable of high efficiency, simplicity, reliability and long life.
  • Electrical power generating efficiency of nearly 30 percent is achievable.
  • Combined Heat and Power efficiency greater than 90 percent is achievable.
  • Price of a Rankine CHP system may be as low as $500/kilowatt.

Fluidic microControls, Inc., estimates a market for 90,000, 10-kilowatt digester gas to electrical power modules for herds of 500 cows or fewer. The company¬ís agricultural CHP unit may be applied to provide all the power needs for the farm or for an average home, and it may be simply modified also to burn natural gas. 30 to 50 million homes in North America are candidates for CHP. The high volume potential of the residential market can provide a great reduction in manufacturing costs, allowing Fluidic microControls, Inc., to meet its $500/kilowatt price target for CHP modules for small digesters. The first-year Phase II effort will be concentrated on turbo-alternator design and development. A mass-producible, high­pressure boiler and development of a CHP manufacturing and distribution partner will be a new emphasis in the second year as part of the commercialization option.

Supplemental Keywords:

anaerobic digester, farm, biogas, combustion, solid waste, animal waste, micro energy system, waste-to-energy conversion, waste heat recovery, small farm biogas system, SBIR

Progress and Final Reports:

  • Final

  • SBIR Phase I:

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