Geothermal without the Geysers

When you think geothermal energy, Denmark probably doesn’t come to mind. Geysers and other spectacles of Earth’s immense heat tend to cluster along the edges of tectonic plates—Iceland, Japan, Kenya, to name a few such places. Just because there’s no bubbling mud pots at the surface doesn’t mean there’s no geothermal energy to be found deeper down, and soon that heat from below will be coming to districts near Copenhagen.

A view towards the forest in Ballerup, Denmark. This municipality is one of several planned to receive geothermal energy in their district heating system, despite the landscape looking nothing like a stereotypical geothermal hotspot. Photo credit: Erik Nicolaisen Høy.

The surface doesn’t always hint at what’s below. Beech forests, bogs, and pasture spread around Lyngby-Taarbæk, the Danish municipality where the geothermal facility is planned. A short way north of Copenhagen, deep groundwater below Lyngby-Taarbæk gets as hot as 80 degrees Celsius (176 °F).

Geothermal energy obtained here will supplement an existing district heating system. By sending heat to the nearby waste-to-energy plant, Denmark is using a mix of green energy sources to replace oil and gas heating systems. Once fully expanded with geothermal and other improvements (completion expected in 2028), the district heating network will be roughly doubled in capacity, providing carbon neutral heating to 39,000 homes.