Phototheque VEOLIA

Gas, sludge and sun for a positive energy plant

Posted on 10 June 2016.

Organic matter from wastewater now fuels 92 percent of the Gresham plant’s power. In March, the Gresham facility had its first “net zero month.”

A crowd of both curious students and the local and national press came to discover this site - unique in the Pacific Northwest. The focus of their attention? The trail-blazing wastewater treatment plant in the city of Gresham in Oregon, a few kilometers east of Portland. Its appeal? It went from being one of the biggest energy-users in the municipality to celebrating net-zero energy by turning sludge into biogas. In addition, the city installed one of the largest land-based solar arrays in the Pacific Northwest.

Not a penny spent on energy

Result: in March 2015, for the first time this site achieved its first net-zero month. Its monthly energy costs have gone from $50,000 (just over 44,000 euros) to... not a penny. Being now self-sufficient in energy, the site even gives back its production surplus to the local public services.This zero energy installation was not built in a day. In 2005, the city of Gresham decided to put an alternative in place in order to reduce its energy costs. With biogas in the form of methane naturally derived from the wastewater and a cogeneration unit providing free heat and electricity, it had already reduced its energy consumption by about 20% per month. But it wasn’t enough for Gresham - they wanted to go even further.

Net zero energy can be replicated

In 2005, Gresham chose to partner with Veolia North America because they were looking for a partner who could implement a world-class wastewater program, with the goal of protecting Gresham’s infrastructure assets while improving the environment for this community of more than 100,000. The treatment plant has received numerous awards for the example it sets. A virtuous, positive energy model that has another advantage - it can be replicated in thousands of other wastewater treatment plants all over the US - and the world!