Pumped-hydro energy storage : potential for transformation from single dams (Analysis of the potential for transformation of non-hydropower dams and reservoir hydropower schemes into pumping hydropower schemes in Europe)

Electricity storage is one of the main ways to enable a higher share of variable renewable electricity such as wind and solar, the other being improved interconnections, flexible conventional generation plant, and demand-side management. Pumped hydropower storage (PHS) is currently the only electricity storage technology able to offer large-scale storage as that needed for accommodating renewable electricity under the 2020 EU energy targets. Compared with the high environmental and social impact of most new hydropower plant in Europe, the transformation of an existing reservoir into a PHS system offers the prospects of a much smaller environmental and social impact. The authors developed a geographical information systems (GIS) -based methodology and model to identify the potential for transforming single reservoirs into PHS systems, and to assess the additional energy storage which these new PHS could contribute to the electricity systems. The methodology was applied as case studies to Croatia and Turkey. GIS-based tools have the potential for effective and efficient identification of both national/EU potentials (of policy and scientific-interest) and individual site candidates for transformation (prefeasibility, project-level). Once the model is set up, improvements to such tools, e.g. allowing better sensitivity analysis, can be effectively applied to the whole of the EU with minimum effort. This paper first summarises the methodology and tool used and then exposes the results of its application to two countries as case studies. These results limit the assessment to potential sites within 5 km of one existing reservoir (TA) or of one another (TB), and a minimum 150 m of head. In the case of Croatia, it was found that at least a potential of 60 GWh is possible for which can be compared with the existing 20 GWh of storage capacity at its PHS plants. In the case of Turkey a potential of 3 800 GWh was assessed mostly under TA, with 2 potential TB sites providing three additional GWh of storage potential.