Jun 30, 2011

Wastewater Plant Aims to Achieve and Exceed Energy Independence.

David Schaller - Gresham Oregon has begun transforming its wastewater treatment plant (WWTP) from an energy hog to an energy provider.
The city’s initial goal for the 20-million-gallons-per-day (mgd) facility is to have it achieve energy independence by 2015. The City is using a cogeneration engine that converts methane gas from the WWTP’s digesters, into energy for electrical power and heat. The methane-to-energy solution has helped Gresham WWTP cut its electricity costs by about $23,000 per month, and today the facility produces half of the energy it consumes. Further fueling the plant is a 419-kW solar array, expected to supply 7% of the WWTP’s yearly demand. The facility also acquires wind power from in-state wind farms via Portland General Electric’s Clean Wind Program, generating another 18% of Gresham WWTP’s energy. The facility currently produces about 60% of its power on site. A new fats, oils and grease receiving station will increase digester gas production, and a second co-generator will use this gas to fill the plant’s energy gap. Furthermore, plans are in place to install high-efficiency aeration blowers and to swap out the current digester mixing system for more energy-efficient technology. Ultimately, the facility plans not only to produce enough energy for its own needs but also surplus energy that can be added to the grid for other local needs. 
Read more at Water and Wastes Digest