Heat supply: How heat from the ground could be recycled for heating

The accumulated heat in the earth’s subsoil has great potential for providing heat to people. The heat generated by urbanization, industrialization, and climate change could be tapped with shallow geothermal systems and provide nearly all the heat needed in many regions of the world for decades. This is shown by an international research team, in which Martin Luther University Halle-Wittenberg (MLU) was also involved, in a new study published in the journal Nature Communications.

According to the Federal Environment Agency, around two-thirds of energy consumption in German households is attributable to space heating. Most of this energy is generated by burning fossil fuels – an expensive resource that also contributes significantly to climate change. “In the search for low-carbon alternatives, little attention has been paid to recycling the heat that accumulates in the shallow subsurface due to urbanization, industrialization and climate change,” says Prof. Dr. Peter Bayer of the Institute of Geosciences and Geography at MLU. Yet this could be developed relatively easily with very shallow geothermal systems.

In the new study, an international research team led by Dalhousie University in Canada investigated whether such large-scale heat recovery would be feasible. The researchers found that heat has already accumulated at about 50 percent of all sites studied worldwide. They calculated that by 2099, between 73 and 97 percent of regions in North America, Europe and Australia could meet their annual heating needs with this recycled heat. At the same time, the team assumes that this would lower temperatures in the subsurface. “Should policymakers and stakeholders decide against this low-carbon heating method, heat will continue to accumulate in the ground and affect groundwater quality and ecosystems,” concludes study leader Dr. Susanne Benz of Dalhousie University.