The Green Grid
Copenhagen has done what most cities only promise: its entire district heating system now runs on renewable energy. Biomass, geothermal, heat pumps, and waste incineration have fully replaced coal and natural gas — three years ahead of the city's own 2028 target.
The achievement is the result of three decades of infrastructure investment, beginning with the decision in the 1990s to connect virtually every building in the city to the district heating network. Today, 99% of Copenhagen households receive their heat through the system.
How They Did It
The key was not any single technology but the integration of multiple sources. Biomass plants provide baseload heat. Geothermal wells — some reaching 3 kilometres deep — supplement during peak demand. And a fleet of industrial-scale heat pumps captures waste heat from data centres and wastewater treatment plants.
"The lesson for other cities is that you don't need a silver bullet," says Lars Aagaard, Denmark's Minister for Climate, Energy and Utilities. "You need a system."
What It Means for Other Cities
Helsinki, Stockholm, and Tallinn are all following Copenhagen's model. The technology is proven. The economics work. The question is speed of deployment.