Biogas To Power Austin Sewage Treatment Process

The purchase of a green-powered generator made possible with federal stimulus funds will provide all the electricity needed to run the Hornsby Bend Biosolids Management Plant in Southeast Austin.

The Austin City Council approved the $1.2 million purchase on Thursday, May 26. Funding is from a $7.5 million federal stimulus grant awarded to Austin Energy to increase the energy efficiency of municipal facilities. Austin Energy is the energy manager for the City of Austin.

The biogas generator will utilize methane from the sludge treatment process at Hornsby Bend and will be able to consistently generate 700 kilowatts (kW) of power, more than the 500 kW needed to run the treatment plant. The excess electricity produced and fed back into the electric grid will enable Austin Water, which manages the treatment plant, to receive a credit on its electric bill.

Because the generator uses the methane and not a fossil fuel, the electricity produced is considered renewable energy. It is estimated that more than 4.4 million kilowatt-hours of electricity will be generated annually, the equivalent of powering 370 average-sized Austin homes year round. The clean generation also will reduce carbon dioxide emissions by 2,867 tons or the equivalent of avoiding 5 million vehicle miles traveled in Austin.

The Council action also includes an option for Austin Water to enter into an eight-year maintenance agreement for $1.5 million if funding is available to provide regularly scheduled preventative maintenance and corrective maintenance to extend the life of the generator.

The generator is funded separately but related to green infrastructure improvements currently under way at Hornsby Bend by Austin Water to enhance the energy efficiency of the biosolids processing and increase biogas production.
Hornsby Bend receives the sewage solids reclaimed from the millions of gallons of wastewater that Austin’s wastewater plants treat every day. All of Austin’s sewage solids are pumped to Hornsby Bend where they are treated to kill pathogens and the resulting biosolids are recycled as the compost product ‘Dillo Dirt.’