Elsevier

Applied Energy

Volume 179, 1 October 2016, Pages 1242-1250
Applied Energy

Pumped hydro energy storage in buildings

https://doi.org/10.1016/j.apenergy.2016.07.046Get rights and content

Highlights

  • Novel analysis of unique building with integrated pumped hydro energy storage system.

  • Full parameterisation of pumped hydro energy storage in buildings.

  • Feasibility of pumped hydro energy storage in buildings is studied.

  • Conditions for a better competitiveness of this technology are discussed.

Abstract

The growing use of variable energy sources is pushing the need for energy storage. With Pumped Hydro Energy Storage (PHES) representing most of the world’s energy storage installed capacity and given its maturity and simplicity, the question stands as to whether this technology could be used on a smaller scale, namely in buildings. In this paper, the feasibility of such an installation is analysed by modelling each one of its components and applying it to several installation scenarios. Proposed and existing installations are also reviewed, including a first-time analysis of an installation in France, which is presumably the only existing building with an integrated PHES system. It was found that the economies of scale that render large PHES installations competitive are not present in small installations. This limitation, associated to other important disadvantages, such as the large volume required, seem to point out PHES as an ill-suited solution for energy storage in buildings, an important finding for building design and energy policy. Nevertheless, if synergies with existing reservoirs could be found (for example for a building on a riverside), costs could be significantly lowered. Further research on possible synergies with other building systems as well as a life-cycle assessment analysis are recommended.

Introduction

With the increasing use of variable energy sources in power grids, there is a growing mismatch between when energy is produced and when it is consumed [1], [2]. This has led to the need for energy storage or demand-response in favour of a balanced and efficient use of energy [3], [4]. At the same time, there is a growing trend towards the decentralisation of power sources (like photovoltaics), which coupled with the important share of energy consumption in buildings suggests that these will play an ever more important role in the electric power industry, namely through decentralised energy storage [5]. There are different technologies available for energy storage but, on a global scale, most of the energy storage capacity comes from large installations of Pumped Hydro Energy Storage (PHES) [3]. Today, it is a well-known technology offering water storage and easy installation and maintenance due to its simplicity and maturity [5], [6].

The characteristics of PHES have raised the interest for smaller-scale installations [7], [8], namely in buildings, but there is still a significant lack of information regarding the technical feasibility and economic viability of PHES in buildings which needs to be addressed [1], [3], [5]. Currently, the availability and characteristics of the required equipment (such as water turbines or water storage tanks) for such an installation are not clear, especially given the scarce theoretical studies available and the absence of data on real installations [7]. The energy storage potential and its impact on the building’s consumption also require assessment. Design methods, such as the choice to install variable-frequency turbomachinery, need further research to take into account the specifics of small-scale installations [7]. Such specifics also require further research in the case of multiple storage systems, whose complexity hinders an optimal design and operation [1]. The interaction between water supply systems and energy storage also needs to be assessed [3]: though water distribution systems can be used for demand-response [9] and show good complementarity with PV installations [10], the question stands whether synergies could be found between such systems in a building.

To account for the research gaps described before, proposed and existing installations found in the literature are reviewed and, for the first time, an existing building with an integrated PHES system (the only one of its kind, to the authors’ knowledge) is analysed. All components of the PHES system are then parameterised, providing important data to designers and researchers. A PHES installation in a building is modelled and the technical and economic feasibility of such installation is discussed.

Section 2 starts with a description of proposed and existing installations. In Section 3 the PHES parameterisation and modelling is presented and discussed, followed by the results for different scenarios and discussion in Section 4 and the conclusions in Section 5.

Section snippets

Existing and proposed PHES systems in buildings

For PHES, two reservoirs at different heights are used. To store energy, water is pumped from the lower reservoir to the higher reservoir. To later retrieve that energy, water is transferred from the higher reservoir to the lower reservoir through a turbine [6]. The use of small-scale PHES has been studied before but for power and energy capacities several times superior to those that could fit in a building [11], [12]. Caralis et al. [13] and Ma et al. [7], for instance, provide estimates for

PHES modelling

For PHES, two reservoirs at different heights are used. To store energy, water is pumped from the lower to the higher reservoir. Later, that energy can be retrieved by passing the water from the higher reservoir to the lower reservoir through a turbine. The amount of energy stored E (J) is given byE=ρV g hwhere ρ is the density of water (kg/m3), V is the volume of water at the higher reservoir (m3), g is the gravitational acceleration (m/s2) and h is the height difference between reservoirs (m)

Case studies

Using the results obtained previously, two different case studies for PHES in buildings were developed (Table 2).

As seen before, there are important economies of scale associated to PHES. As so, only tall buildings, namely apartment buildings, will be considered: a theoretical 20 m height building with a floor surface of about 200 m2, enough to house four 50 m2 apartments per floor (as in the Goudemand residence) or two 100 m2 apartments per floor (Table 3).

In both cases an open top reservoir is

Conclusion

PHES in buildings is technically feasible. However, when associated to local sources of energy in a building, it is still far from reaching grid parity. Furthermore, it is not economically competitive when compared to other small-scale energy storage systems that can be incorporated into a building, given the inexistent scale economies that render high capacity PHES installations competitive: a fundamental finding for consideration in building design and energy policy. The inexistence of these

Acknowledgements

This study has been done in the framework of the Micro Energy Storage in Buildings project, part of the Brussels Retrofit XL research platform funded by Innoviris, the Brussels Institute for Research and Innovation. We would like to thank Mr. Louart and Mr. De Backer from CRC (France) for their guided visit to the Goudemand residence and in providing much needed information for this paper. The authors are also indebted to the numerous reviewers who provided invaluable insight and much

References (36)

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