Case Study: Municipal Sustainability


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PHGE Brings Renewable Energy, Diverts Wood & Sludge from Landfill

Progressive civic leaders in Covington, TN, knew there was a better solution to disposing of wood waste and sludge than hauling thousands of tons to a landfill every year and paying tipping fees. PHG Energy designed and installed the company’s first municipal gasification system at the city’s waste water treatment plant in 2013, and used the resulting fuel gas to power an innovative electrical generation technology from General Electric. The renewable energy was used to offset power costs at the treatment plant. Disposal cost offsets were redeployed to provide improvements in the city’s parks system.

Projected Benefits:

  • 900,000 pounds (450 tons) of carbon emissions can be kept out of the air each year, which equates to the CO2 produced annually to provide electricity to 35 homes, or the annual Greenhouse Gas Emissions from over 80 passenger vehicles.
  • Over 8,000,000 pounds (4,000 tons) of waste material can be diverted from landfills annually.
  • System can provide over a 750,000 Kilowatt hours of renewable electricity over the 20-year life of the project.
  • City was awarded a $250,000 Clean Energy Grant from the Tennessee Department of Environment and Conservation (TDEC).

The System Details:

  • 12- ton/day capacity throughput PHG Energy downdraft gasifier is core technology
  • Wood is chipped, mixed with sludge and pre-dryed to control moisture content before gasification.
  • Syngas produced (92% by volume input) is combusted in industrial thermal oxidizer (an emissions control device).
  • Thermal energy is transferred to heat oil fluid.
  • Hot oil drives a 125 Kw General Electric Organic Rankine Cycle generator.
  • 8% of input results in biochar which is 70% carbon and recyclable

NOTE: In July of 2015, PHG Energy assumed operation and fiscal responsibility for the plant in an agreement with Covington. The system is currently being used for advanced energy R&D purposes.

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