Water and wastewater operations use a substantial amount of a municipality’s energy. As cities work to become climate change resilient, reducing carbon emissions is key. Lowering the energy use of a city’s water utility can help municipalities reach their carbon reduction goals.
Cities can start with simple improvements like replacing current lighting with LEDs and light timers. Heavier lifts include improving pumping stations and timing pumping to be most efficient, and updating or adding meters for ratepayers to help detect leaks and other water conservation programs. Efficiency at all levels is important, so installing water meters to help detect leaks for ratepayers and for municipal buildings, and then securing those leaks, should be priorities.
After all efficiency opportunities are addressed, utilities should move to new construction opportunities. One of the more visible options is the construction of biodigesters. These facilities are a big investment, but they can also yield big returns. Biodigesters convert a city’s waste and wastewater into biogas, which is then syphoned off and used to power the facility itself.
There is danger for cities to overreach in their investment by going too big too soon. By building to become an energy producer instead of net-zero, the facility might become cost ineffective. Instead, cities should look for grants and state funding, and invest in a facility that can partially power itself first.
What Cities Can Do
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Grand Rapids, MI’s $38 million digester is a good example of a new facility approach. The City broke ground in the winter of 2018, and is part of a much larger process to make themselves an “all-renewable-powered city.” This facility is just one piece of a larger vision, but one that will go a long way to reducing the carbon use of their waste water and improving water utility energy efficiency, easing the way for alternative energy sources to power the city- which includes the biodigester itself. And actually, breaking ground on a new facility ended up saving Grand Rapids money over expansion of an old facility.
Stevens Point, WI has long invested and upgraded their wastewater treatment plant to be one of model efficiency, and through a series of upgrades they’ve been able to build a model biodigester facility.
Downer Groves Sanitary District, in Illinois, built a cost effective net-zero energy wastewater treatment plant. Through diverse investments over the past 10 years they were able to create this facility and converted what was an energy user into an energy resource.
April 2015 Gresham, Oregon was able to achieve net zero energy status for their wastewater plant, making it one of the first in the USA to achieve this status. They were able to do this through an active mayor and utility director.
For larger metropolitan areas, DC Water is a great example of how to improve efficiency within water and wastewater utilities. They became the first city in “North America to generate clean and renewable energy from wastewater.”
East Bay Mud Municipal Utility District is another great example of how to build, upgrade, and maintain a cost-effective digester facility. Through efficiency and creating a direct line from high biowaste producers to their facility, they’ve been able to create an increasingly efficient plant.
Stevens Point WI, is also a prime example of retrofitting and scaling older facilities to bring them up to date and aid in reducing energy use for wastewater facilities.