The thermoactive pavement: a new solution to regenerate geothermal fields

Over the last decade, road construction companies have developed innovative solutions that integrate new functions into roads, such as the ability to generate renewable energy. One such technology involves harvesting solar thermal energy through a heat exchanger made up of pipe registers integrated into the pavement. The energy is mainly harvested during the summer, taking advantage of the large black surfaces that roads offer. However, heating needs are significantly higher in winter than in summer, making seasonal storage a critical aspect of this technology. Recent developments have focused on understanding and optimizing the storage of solar heat using shallow geothermal technologies. This paper examines the capability of thermoactive pavements to harvest solar energy and recharge a geothermal probe field. The authors present observations from two operational facilities in France, which provide renewable heat to a customer office at a toll station near to Paris and to social housing in Normandy. Two main parameters were studied: the annual energy balance between the pavement and the probe fields, and the evolution of the temperature annually and over several years. Based on these two experiences, the ability of a thermoactive pavement to recharge a geothermal probe field has been positively assessed. Like solar thermal energy, this system contributes to the regeneration of the soil. This ensures the long-term dimensioning of geothermal production and allows for optimization of the geothermal field's size. The road infrastructure, on the other hand, does not require additional space, as it is already an integral part of our urban landscapes.