Renewable Power Generation

Salem's new Cogeneration Plant produces renewable power (heat and electricity) from the by-products of wastewater treatment (methane biogas). The renewable power that is produced helps to offset energy costs at the Willow Lake Wastewater Pollution Control Facility and significantly reduces the amount of pollution-causing greenhouse gas (biogas) and carbon dioxide that is released into the atmosphere.

Cogen Video Clips

Cogeneration

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

How Cogeneration Works

Key components of a 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 Cogeneration 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

How Methane (Biogas) Is 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

The new cogeneration facility at the Willow Lake Water Treatment Pollution Control Facility will produce up to 1200 kW of renewable electricity from biogas produced as a byproduct of wastewater treatment processes; enough energy to power 900 homes.

Project History

From 1988 until 2020, the City of Salem has operated a 650kW cogeneration facility to generate power from biogas produced as a byproduct of wastewater treatment processes at its Willow Lake Water Pollution Control Facility. The system is was at the end of its useful life and is undersized for the quantity of biogas produced.

The objectives of the Cogeneration Facility Upgrade project are:

• Maximize the utilization use of available biogas produced to produce generate clean and reliable renewable energy.
• More efficiently and reliably generate electricity from biogas.
• Utilize Use waste heat from electricity generation.
• Reduce the City's reliance on non-renewable power sources.
• Provide environmental and economic value to the community and the City's ratepayers.
• Replace the existing cogeneration system, which is at the end of its useful life.

Project Costs

• A $3,000,000 grant from Portland General Electric's Renewable Development Fund. This funding was made possible by PGE's Green Future℠.
• A $3,000,000 Renewable Energy Project Installation Incentive from Energy Trust of Oregon
• A $250,000 Renewable Energy Development Grant from Oregon Department of Energy
• A $200,000 Project Development Assistance Incentive from Energy Trust of Oregon
• Approximately $138,000 in Energy Efficiency Incentives from Energy Trust of Oregon
• City sewer and water rates funds.

Total Project Cost: $11,180,000

Funding Partners

This project was made possible with funding support from the Portland General Electric (PGE) Renewable Development Fund, with additional support from Energy Trust of Oregon.

Additional Resources

Willow Lake Wastewater Treatment has several projects underway to help our community continue to find ways to save and conserve resources.