Denver Taps Sewage for Geothermal Heat Network

Denver is embarking on an innovative project to decarbonize its downtown core by establishing a thermal energy network. This system will leverage a unique combination of water circulation, geothermal heat from the Earth, and heat recovered from sewage to provide heating and cooling for a cluster of buildings. The city aims to significantly reduce greenhouse gas emissions, targeting zero by 2040, and expects to save taxpayer dollars.

The initiative involves repurposing the historic Cherokee Boiler House as a central hub for this new network, dubbed an "ambient loop." This system will circulate tepid water through underground pipes, connecting 11 city-owned buildings. Water-source heat pumps within each building will efficiently transfer heat to or from the circulating water, enabling shared energy between buildings.

To supplement the loop, Denver plans to drill hundreds of geothermal boreholes, tapping into the Earth's consistent underground temperature. Additionally, the project will harness thermal energy from wastewater before it is discharged, a source of heat previously unrecognized as a utility. This multifaceted approach is projected to be significantly cheaper than other decarbonization methods.

The city plans a phased rollout, beginning with a micro-version connecting two buildings and a snowmelt system in approximately two years. By 2030, the goal is to have nine buildings integrated into the network. Mayor Mike Johnston believes that if successful, this system can be adapted for thousands of natural gas customers downtown, accelerating Denver's emissions reduction goals and potentially inspiring similar projects nationwide.