How poop and produce can combine to power Chilliwack homes

That banana peel you just threw in the compost could soon power someone’s home—if you live in Chilliwack.

The City of Chilliwack is upgrading the capacity of its wastewater treatment plant, and is about to do something novel in the process: use food waste alongside to produce natural gas, and cut the city’s greenhouse gas emissions.

Turning wastewater into natural gas isn’t new in the Fraser Valley, but adding organic waste to it is. Currently, the contents of Chilliwack’s green bins are transported to Net Zero Waste in Abbotsford, which turns the waste into compost at its Gladwin Road facility. The anaerobic digesters at Chilliwack’s wastewater treatment plant are already converting the city’s sewage into biogas that helps power the plant, although excess gas is often flared. (Anaerobic digesters work because microorganisms within the tank eat the organic material in the sludge and turn it into gas.)

A new project in Los Angeles saw green bin waste turned into a liquid slurry (not unlike a milkshake) that was added to the digesters at a wastewater treatment plant to produce more biogas. That biogas is then used to power the plant, and extra gas is refined and sold. That project inspired Chilliwack to look into using its own food waste in digesters, with a goal of selling the surplus gas to FortisBC.

A 2018 feasibility study found that adding food waste to the digester would increase the amount of biogas produced by 30%. More biogas makes it economically feasible to “scrub” the gas and turn it into biomethane, or renewable natural gas. However, the current digester at Chilliwack’s plant is nearing capacity, which meant there wouldn’t be enough room to process the organic waste even if the city wanted to. That meant a new anaerobic digester would have to be part of the construction project, along with the pre-processing station at the Bailey Landfill.

The project is expected to cost $9.5 million and has already received $6.6 million in funding from the provincial government. It will include a pre-processing system at the landfill’s existing organic transfer station, the new anaerobic digester at the wastewater treatment plant, and a new slurry transfer system. Several new tanks must also be built.

Once the Chilliwack project is complete, it will become the fifth place to provide biogas to FortisBC. Right now, FortisBC receives biogas from Abbotsford’s Fraser Valley Biogas, along with operations in Kelowna, Salmon Arm, Delta, and Surrey. (Fraser Valley Biogas was the first organization to provide biogas to FortisBC and was recently purchased by EverGen, which also operates Net Zero Waste.)

The city isn’t expecting to receive much revenue from FortisBC for its contributions, just enough to help cover the cost of scrubbing the gas, with a bit of extra profit. Most of the city’s organic waste will still go to Net Zero Waste, with maybe around 10% destined for the digesters. But the project will help the municipality become carbon neutral, something Chilliwack has been working towards under the soon-to-be-ended Climate Action Revenue Incentive program. (In 2019, Chilliwack had 4,773 tonnes of greenhouse gas emissions from corporate services, which includes vehicles, equipment and machinery.)

Currently, the Chilliwack project is soliciting bids for the project. Two bids are expected back in August, and the entire project is expected to be complete by the end of 2022.