The research at Ohio University could help transform old fossil fuel sites into clean energy assets, though much work remains to be done.
Utilities could prove useful partners in the projects, which involve drilling, trenching and laying pipe to bring underground heat into buildings.
One participant, the University of Minnesota at Morris, already uses 100% renewable electricity, but is now looking for options to eliminate its natural gas heating systems.
A startup company is beginning to market geothermal systems that circulate heat from shallow aquifers.
A developer is pursuing city financing to build an aquifer thermal energy system as an alternative to natural gas.