Wastewater Treatment Plants as Anchor Infrastructure for Geothermal Energy in Cold Regions

Abstract

Thermal constraints in cold regions suppress biological treatment, increase energy demand, and elevate greenhouse gas emissions of existing wastewater treatment plants (WWTPs), and remain a major barrier to the deployment of adequate sanitation infrastructure in many cold-region communities. Where geothermal resources exist, low-enthalpy hydrothermal heat is well matched to this energy gap. Yet, WWTPs are underrecognized anchors for broader geothermal deployment, providing a continuous, weather-independent thermal offtake through which subsurface CAPEX can be amortized. We reframe geothermal-WWTP integration as a system-level enabler that benefits both parts. Using three cascaded configurations for a full-scale WWTP, a rapid techno-economic analysis identifies three trends: energy and carbon savings/revenues alone are insufficient under realistic policy stacks, whereas crediting the upgrade-deferral value of geothermally enhanced treatment makes the project economically favorable across most policy scenarios. Globally, this triple intersection encompasses ∼11,600 catalogued WWTPs serving ∼280 million people, with a further estimate of ∼48 million people in the same regions beyond current service radii. The opportunity is greatest in cold, remote, and underserved communities, where local geothermal resources, treatment intensification, and community-scale demand together carry a case that no single driver could sustain alone.