WWTP	use sewage gas to power Caterpillar gas generator sets.

Utilizing Methane for Power Production

Many wastewater treatment facilities use waste gas from plant processes as a generator set fuel source. This gas is comprised of mostly methane and carbon dioxide that is generated by wastewater digesters used in the water treatment process. This gas is then captured and used by Cat® generator sets to provide the plant with electricity and heat for the digester or other thermal loads. Caterpillar customers receive expert consultation on how to design, install and maintain power plants designed especially for wastewater plant gas fuel.

Benefits from methane-to-energy projects include:

  • Increased energy efficiency
  • Reduced electricity costs
  • Decreased environmental impact

How It Works

A durable engine specifically designed for use with low-energy fuel is the cornerstone of a reliable power system. That engine drives a Cat generator to produce electricity.

Cat low-energy fuel generator sets offer a specialized tolerance to the contaminants in sewage gas fuels by offering additional features that include:

  • Crankcase ventilation pump to eject potentially acidic blow-by gases
  • Specially designed aftercooler cores, cylinder heads, main bearings and connecting rod bearings that are hardened against corrosive elements
  • Differentiated cooling systems to operate at elevated jacket water temperatures to prevent condensation of contaminants

Heated engine jacket water passes through a plate-and-frame heat exchanger that is connected to the treatment plant's process heat loop. Additional heat can be recovered from the aftercooler circuit as well as the engine's exhaust. The system is typically electrically integrated into the facility via Cat utility grade paralleling switchgear with PLC-based controls that allow electricity to be exported to the grid or used exclusively by the facility.

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