Shallow geothermal energy

Geothermics is the science that deals with the transport and the utilisation of the heat stored in the underground in different forms (hot rocks or fluids), depths (from a few meters to a few kilometres) and temperatures (from less than 10°C to more than 300°C).

The Groundwater Engineering research group deals with shallow and low-enthalpy geothermal resources which, according to international definitions, are below 90°C of temperature and are located at reduced depths (less than 400 m).

Shallow geothermal systems are divided into two categories:

  • closed-loop systems, in which a heat carrier fluid is pushed to circulate into a pipe loop buried in the ground in different ways (borehole heat exchangers, energy piles, horizontal coils);
  • open-loop systems, in which the heat exchange is performed on groundwater extracted by a well and usually re-injected downstream by another well after the heat exchange (Ground Water Heat Pumps, GWHP).
Closed-loop (on the left) and open loop (on the right) shallow geothermal systems. Source: EHPA

Although these technologies are convenient both from the economic and environmental point of view, the high costs of installation and of electrical energy still impair the growth of shallow geothermal installations, and research should tackle these issues.

The research activity of the Groundwater Engineering group is focused on:

  • numerical modelling of shallow geothermal systems, both closed-loop and open-loop;
  • development of simplified numerical and analytical models to solve design issues of GSHPs;
  • assessment and mapping of shallow geothermal potential, i.e. the thermal power which can be efficiently exchanged with the ground(water) depending on its thermal and hydrogeological properties;
  • policy development for the sustainable growth of GSHP installations.

Details on past and ongoing research activities are reported at the following pages:

  • the GRETA project, funded by EU Interreg Alpine Space program (December 2015-2018). Further details here;
  • the exchange project between Italy and Québec “Evaluation du potentiel géothermique face la production agricole au nord du Québec et en Italie” (July 2017 – December 2019). Further details here;
  • the development of the G.POT method for the estimation of the shallow geothermal potential (October 2014 – April 2016). Further details here;
  • the assessment of the shallow geothermal potential in the province of Cuneo (October 2014 – September 2015), funded by Fondazione CRC. Further details here;
  • the development of the numerical code Thermal Recycling Simulator (TRS) for the assessment of thermal short-circuit in Groundwater Heat Pumps (January 2013 – December 2014). Further details here;