Evansville Water and Sewer Utility (EWSU) has long been interested in utilizing renewable energy to lower operational costs, reduce greenhouse emissions and protect the environment. To meet these objectives, EWSU is making strategic investments in solar energy and renewable natural gas, which in turn will generate revenue for the Utility and pay for improvements over time.
A solar array at the Campground Reservoir generates more than 350,000 kilowatts of electricity annually without creating any carbon dioxide emissions. The amount of energy produced is worth about $45,000 a year, and the project will pay for itself in 10 years. Through net metering, the Utility is able to export excess power back into the power grid to offset future energy costs. Two additional solar arrays power a sewer lift station on Millersburg Road and the Operations Facility on Allens Lane.
EWSU saves hundreds of thousands of dollars in energy costs each year by recycling fats, oils and grease (FOG) from local restaurants and commercial kitchens. FOG is brought to the East Wastewater Treatment Plant for processing in aerobic digesters to break down wastewater solids. The process creates methane gas, which is burned off producing enough electricity to supply up to 70 percent of the power used at the plant. The residual heat from the electrical generation process is also captured and used to heat the boiler systems used at the plant.
EWSU is launching a new project that will produce Renewable Natural Gas at the West Wastewater Treatment Plant. As part of the biological treatment process, biogas from decomposing wastewater solids is captured in an aerobic digester to filter out byproducts, one of which is methane. The methane is then filtered to remove impurities creating clean natural gas.