The City of Denver and its wastewater utility announced a plan this week to build a geothermal network that captures heat from sewage [1, 2].
The project aims to eliminate the use of fossil fuels for heating and cooling downtown buildings. Because buildings represent Denver's largest source of greenhouse-gas emissions, this transition is a critical component of the city's climate goals [1, 2].
The system will target wastewater that is currently discharged into the South Platte River [1, 2]. By extracting thermal energy from the sewage, the city can create a sustainable loop of heating and cooling for the urban core. This process serves a dual purpose by cooling the wastewater before it reaches the river, which improves overall water quality [1, 2].
City officials and Denver Water said they intend to implement the network over the coming years [1, 2]. The infrastructure will allow downtown properties to move away from traditional gas-fired boilers and carbon-intensive cooling systems. This approach leverages existing waste streams to provide a consistent energy source without the need for traditional drilling or deep-well geothermal exploration.
The initiative focuses on the high-density environment of downtown Denver, where the concentration of wastewater pipes provides a concentrated source of heat [1, 2]. By integrating the utility's wastewater management with the city's energy needs, Denver is attempting to decarbonize its building sector while protecting the local aquatic ecosystem.
“Denver is creating a geothermal system that harvests heat from its sewage.”
This project represents a shift toward 'sewer thermal' energy, a form of urban geothermal recovery. By treating wastewater as an energy asset rather than just a waste product, Denver is addressing two environmental challenges simultaneously: reducing urban carbon footprints and mitigating thermal pollution in river systems.
