Thermal inspection of water pit heat storages using drones

Water pit heat storages can be used to cover the mismatch between solar thermal generation and heat demand and achieve high solar thermal fractions in district heating systems. The most expensive part of such storages is the floating insulating lid, which is crucial to ensuring high efficiency by minimizing heat losses. So far two different insulation materials have been used in the lids, namely Nomalén and LECA, both of which are sensitive to moisture. It is therefore important that leakages, which existing storages have been prone to develop, are fixed quickly. Due to the large surface area of the lids (>10.000 m^2), manual inspection is costly and inefficient. This study investigates if thermal drone imaging can be used to identify leakages in pit storage lids, by inspecting all existing pit storages in Denmark. The investigations led to the identification of leakages in two different pit storages and proved that drone thermal imaging is a very effective tool for leakage detection.