Geothermal energy: harnessing the Earth's heat

BRGM's geothermal platform in Orleans compares the efficiency of various techniques to exchange heat, in summer and winter, between buildings and the subsoil. The goal of the platform is to describe the mechanism of conditions, such as wind, rain, sun, and the Earth's heat. Understanding the resource will help us to manage and use it better. The first systems installed and studied were horizontal collectors. This simple and economical technique is not the most efficient, but it gives us keys to understand other collectors. We can also choose to stabilise the thermal resource by using vertical geothermal probes. The same is done with aquifer solutions. Today, we are also finding intermediate solutions, such as the systems known as compact exchangers. Their efficiency has not yet been fully studied, but their simple installation with a digger makes this system the ideal companion for future green houses and buildings. By circulating water in the exchangers at a fixed temperature and outflow, we can simulate energy needs in terms of heat and cold for any building. We can reproduce the behaviour of homes, of all existing heat pumps, and those which are still concepts. This installation shows nearly 10,000 temperature measurements every 2 minutes with optical fibre technology. Two engineers, 2 PhD students and one control systems technician were hired to run the platform.