Renewable Power Generation

Aerial view of biogas plant.

Aerial view of biogas plant.

​Cogeneration, also known as Combined Heat and Power or CHP, is the simultaneous production of two types of energy – heat and electricity – from one fuel source, often methane. The ability to create two forms of energy from a single source offers tremendous efficiency and thus cost savings and environmental benefits.

CHP is most efficient when heat can be used on-site or very close to it.

How is methane produced?

Anaerobic digestion is a biological process that occurs naturally when microorganisms break down organic matter in environments with little or no oxygen such as wastewater anaerobic digesters. This process produces biogas, a mixture of mostly methane and carbon dioxide with trace amounts of other gases.

The natural activity of these organisms is harnessed industrially to convert wastewater sludge into a biogas. This biogas can be combusted in the following ways:

  • to generate electricity and heat
  • processed to remove non-methane compounds as a direct replacement for natural gas
  • converted into renewable hydrocarbon liquid transportation fuels
Details on how methane is produced.

How methane is produced.

Daily power generation and carbon reductions

The Willow Lake Cogeneration Facility produced 27,331 net kilowatt hours (kWh) yesterday. Over the last 30 days, the cogeneration facility has produced 655,565 net kWh.

Based on the rolling 30-day production, the cogeneration facility has reduced the annual carbon released to the atmosphere by 821.53 tons. This carbon reduction is equivalent to taking 162 cars off the road per year.

The annual electricity production would be enough to power 727 average homes for a year.

Combined Heat and Power (CHP)

Key components of a CHP system include:

  • Internal combustion
  • Reciprocating engine driving an electric generator

The clean methane fired engine spins a generator to produce electricity. The natural byproduct of the working engine is heat. The heat is captured and used to supply space heating or produce domestic hot water. The CHP process is very similar to an automobile, where the engine provides the power to rotate the wheels and the byproduct, heat, is used to keep the passengers warm in the cabin during the winter months.


Cogeneration workflow

Cogeneration workflow

​Additional information

Contact us

Stephanie EisnerOperations ManagerPublic Works Department
5915 Windsor Island Road N
Salem OR 97303