In Arras, France, amongst the innumerous historical buildings there is a contemporary one, the Goudemand residence, making history by itself. The building, managed by Pas-de-Calais habitat, the region’s social operator, has been recently renovated with the implementation of solar panels and wind turbines on the roof in an effort to render it grid-independent. But what makes such building really unique is the presence of an open water storage tank in the roof connected to another one in the basement.
The system is used as a giant battery: to store energy, water is pumped from the lower to the higher reservoir. To later retrieve that energy, water is transferred from the higher reservoir to the lower reservoir through a turbine. The concept is not new. Pumped hydro is the most widely deployed energy storage technology worldwide. In Belgium, one example is the Coo-Trois-Ponts power station that provides an important balancing of the national power grid and has the main task of reactivating the power grid in case of blackout. Despite typically consisting of very large installations, the maturity and simplicity of pumped hydro has frequently prompted the question as to whether such technology could be used on a smaller scale, namely in buildings.
Recently, at least part of that question has been demystified in the article Pumped hydro energy storage in buildings published in the Applied Energy journal by researchers Guilherme Silva and Patrick Hendrick from the Université Libre de Bruxelles. The researchers started by looking at existing installations and the results seemed grim. Information regarding small installations was scarce and the smallest installation they could find in the literature was for an island in Greece, but still too large to be applied to a building. Hearing about the Goudemand residence, so close to home, was a great boost to morale.
The researchers analysed the installation and built a model that allowed them to extrapolate results for other buildings. They realised that the economies of scale that render large pumped hydro installations economically viable were not present in small installations. Also, a large volume of water is needed, making such installations bulky and heavy, a difficult fit for urban settings. Integrating such installation with the building’s water system is also cumbersome: the water quality would be difficult to control and both systems require a contrasting dimensioning. At the same time, other options for energy storage, such as lithium-ion batteries, enjoy very strong price reductions that are not expected to hit pumped hydro which uses mature technologies such as water pumps.
There is, however, a bright side to it: installations large enough and, for instance, close to canals would have significantly lower costs. Also, the full impact of such installation (on CO2 emissions for example) is yet to be calculated and compared to other technologies. Energy storage still has a long way ahead and only time will tell which technologies make to the end. Until then, installations such as the Goudemand residence help to pump up knowledge on the subject.
Source: Transition énergétique: Pas-de-Calais habitat innove et expérimente l’autonomie énergétique des parties communes dans l’une de ses résidences. Pas-de-Calais habitat press release (2012).
Guilherme de Oliveira e Silva, Patrick Hendrick. Pumped hydro energy storage in buildings. Applied energy 179 (2016) 1242–1250.
Aero-Thermo-Mechanics Dept. (ATM), École Polytechnique, Université Libre de Bruxelles (ULB), Belgium.Go To Applied Energy