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.