Sydney Water is managing to generate more than 15% of its total energy needs through an extensive portfolio of innovative renewable energy projects, including exporting six gigawatt hours (GWh) to the electricity grid. It has also significantly reduced its greenhouse emissions.
“We are aiming to keep our electricity purchases below 1998 levels, even though we are servicing an increasing population and providing higher treatment standards”, said Sydney Water’s Kaia Hodge, Manager Liveable City Programs at the Forum of Doubling Energy Productivity.
“Pumping and treating water and wastewater uses large amounts of energy. By producing our own power on site and by exporting it to the electricity grid, we are producing enough energy to power over 9,000 homes each year.
“Sydney Water is using hydro power generation at North Head wastewater treatment plant, on the Warragamba pipeline, and a pipeline from Woronora dam. These hydro power plants use pressure reduction and gravity flow in water and wastewater streams to generate energy.
“We have also installed cogeneration at eight of our wastewater treatment plants, where biogas is produced from wastewater sludge digesters to generate energy. We have installed a 60 kilowatt solar electric system on the roof of our Potts Hill office building, providing power for the office and an associated warehouse.
“Our energy efficiency and renewable energy teams drive efficient energy use, reduce our carbon footprint and minimise our exposure to energy price rises, the pressures of population growth and increased levels of water and wastewater treatment.
“Greenhouse gas emissions have been reduced by over 60 thousand tonnes a year and further reductions are expected as we expand our solar portfolio and upgrade cogeneration schemes at our Cronulla, North Head and Malabar wastewater treatment plants.
“Sydney Water is researching additional opportunities for co-digestion at our wastewater treatment plants to increase the amount of biogas produced from anaerobic digestion and increase energy yields.
“We are conducting a trial where glycerol, a by-product of biodiesel manufacture, is added to the wastewater treatment process to improve energy generation. At the same time, this reduces the waste stream and reduces impacts on the environment”.
In addition to clean energy generation, Sydney Water is investigating and implementing cost effective projects to reduce energy use.
“Modification of lighting in some of Sydney Water’s treatment plants has achieved electricity savings of around $130,000 a year. Since the start of our energy efficiency program we estimate we have saved about 27.3 GWh, the equivalent of saving greenhouse gas emissions from 3,900 homes for a year,” said Ms Hodge.
“Investment in our energy efficiency programs is being recovered through improved operations and reduced energy costs.
“Generating renewable energy and improving the efficiency of our operations reduces our operating costs and carbon emissions, and enhances our environmental outcomes. This will help keep Sydney Water’s operating costs and customer bills affordable”.