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"Evaluating the energy contribution of small hydropower in the European Mediterranean Basin" e-book released!

The e-book "Evaluating the energy contribution of small hydropower in the European Mediterranean Basin", in the context of the project Save the Blue Heart of Europe, was launched publicly in January 2021 and published online by EuroNatur and This e-book reflects the results of the study coordinated by João Joanaz de Melo and developed also by CENSE researchers António Galvão and Maria João Sousa.

The goal of this study was to develop research to evaluate the potential output of small hydropower (SHP) in the European Mediterranean basin and assess its potential contribution to the region’s energy mix. Two different modelling scenarios were assessed: the “Present” scenario, which depicts an overestimation of the contribution of currently operating SHP plants in the European Mediterranean region, and the “What if?” scenario, which depicts the contributions of existing plus projected SHP plants, for external conditions similar to the 2009-2019 period.

Key conclusions:

  • The potential (overestimated) contribution to the energy mix of existing SHP sites in the European Mediterranean basin is low – on average, around 2.6% of gross electricity consumption and 0.47% of primary energy consumption. The real contribution is likely some 3.5 times lower – falling to around 0.74% of gross electricity consumption and 0.12% of primary energy consumption.

  • Building 5 748 new plants and more than doubling the existing number of SHP plants does not greatly increase the energy contribution of SHP. Potential (overestimated) contribution rises from 2.6% to 4.4% of gross electricity consumption and from 0.47% to 0.79% of primary energy consumption.

  • SHP production is highly dependent on meteorological conditions, varying by more than 50% from the best to the worse years. Results are quite variable by country and year: years of drought in some regions show high productivity in other regions. SHP potential is higher and more stable in mountain regions (due to the combined effect of elevation and orography-induced rainfall). However, the countries with higher number of SHP installations (Italy, France, Spain, Greece) are not those with the higher productivity by plant nor the most resilient to dry years.

  • Mediterranean SHP production will be greatly affected by climate change. In a world 2 °C warmer, stream flow in the Mediterranean region is expected to fall significantly (by 10%-30%). Reduction in hydropower productivity will be even worse with water scarcity prompting higher competition for this resource and rain pattern modifications further decreasing productivity.

  • Investing in (i) energy efficiency and (ii) emerging technologies, such as photovoltaic, is more cost effective than SHP to achieve steady and secure electric systems. The cost of electricity from SHP, measured as the levelized Cost of Energy (LCOE) ranges from 40 to over 300 €/MWh. This is expensive, when compared to the wholesale market price of electricity production in Europe (about 40 to 60 €/MWh), the costs of energy efficiency investments (typically 10 to 40 €/MWh), and the cost of emerging technologies such as photovoltaic (about 50 €/MWh, with a downward trend). While some low-investment, low-impact SHP projects such as refitting existing SHP sites or setting up SHP in waterworks (e.g. irrigation, water supply and wastewater systems) can be economically interesting and environmentally more acceptable, in most cases, SHP is neither a cost-effective way to ensure a reliable electric system, nor to perform the needed energy transition or to reduce carbon emissions.

Download the full report: Melo, J.J., Galvão, A., Sousa, M.J.F. (2020). Evaluating the energy contribution of small hydropower in the European Mediterranean Basin. EuroNatur, RiverWatch and NOVA University Lisbon. 44 pp. ISBN 978-972-8893-85-9.