Energy geostructures: a collection of data from real applications

Energy geostructures are geotechnical structures with the dual role of providing both the important role of structural stability whilst also acting as a heat exchanger with the ground, enabling the supported buildings and or infrastructure to be heated and cooled using the principle of low enthalpy geothermal systems. The main advantage of this innovative technology with respect to standard geothermal plant is the reduction of the initial installation costs and construction programme benefits, compared to installing conventional geothermal solutions, largely due to the supplementary use of structures which would be constructed in any case. However, it is important with respect to energy geostructures that additional aspects need to be carefully considered. For this very reason, several research studies have been carried out over the last decade on this subject and a number of real case studies have been monitored and analysed. The key difference with respect to conventional shallow geothermal systems are mainly due to the geometry, which is imposed by the geotechnical project, and the need for ensuring that the primary structural role is always guaranteed. Special boundary conditions, the reduced depth, the influence of atmospheric external temperature can play an important role for energy geostructures. They can affect, on the one hand, the energy efficiency and, on the other hand, the geotechnical behaviour because of the possible thermal induced mechanical effects. This paper collects available data to provide a reference framework and a picture of the current situation regarding energy geostructures and their peculiar features. Data has been collected from literature and personal communications and then processed to provide easy-to-read charts useful for practical consultation at a glance. This provides, among others, a figure of the distribution of such systems worldwide, their spread in time, and a global idea of their actual efficiency from the structural, energy, economic and environmental point of view