On Thursday, 3 April 2025, the SHERPA project was presented by Iberdrola—project coordinators—at the EPRI European Workshop Week 2025, held in Barcelona, Spain.
Organised annually by EPRI, the European Workshop Week gathers over 200 participants from grid and generation operators, utilities, EPRI’s subject matter experts, and invited stakeholders. The event comprises a series of focused workshops that showcase the latest findings from leading research initiatives and foster collaborative strategies to address the challenges of the energy transition. The 2025 programme included 18 workshops addressing the most pressing issues impacting Europe’s evolving energy landscape.
One of the topics of the event highlighted hydropower’s crucial role in delivering a clean and resilient energy future for Europe. With an ageing fleet averaging 40 years in operation—over 20% of which are more than 60 years old—there is a pressing need for modernisation. As hydropower adapts to support the increasing integration of wind and solar power, its traditional operating modes are shifting, raising the risk of accelerated wear on key components. This session focused on cutting-edge research into materials, repair strategies, and advanced technologies to better understand and manage legacy infrastructure, with the ultimate aim of enhancing the reliability and efficiency of Europe’s hydropower systems.
During the session, Diego Castejón (Iberdrola) introduced the SHERPA project, which stands for Solutions for Hydropower plants to Enhance operational Range, Performance, and improve environmental impact. As project coordinator, Iberdrola leads not only Work Package 8 (Project Coordination and Management) but also Work Package 1, which defines the technical specifications and requirements of each hydropower station. This involves collecting operational and technical data to determine which pilot sites are best suited to trial the various innovations. Iberdrola also leads Work Package 5, which focuses on demonstrations in relevant environments—implementing solutions at pilot sites to validate their feasibility and effectiveness.
Iberdrola is a utility company with over 100 years of experience in hydropower, including the construction and operation of plants. The company manages nearly 12 GW of installed capacity in Spain and Portugal, and approximately 14 GW globally, including 4.4 GW of pumped storage. As coordinators of SHERPA, Iberdrola leads a technically robust consortium comprising seven partners: Voith Hydro Holding GmbH & Co. KG, EPRI Europe, AECOM Spain DCS S.L., Innomerics S.L., AIMEN Technology Centre, and Zabala Innovation Consulting (Brussels).
SHERPA aims to refurbish existing hydropower plants with state-of-the-art solutions to enhance operational flexibility, increase energy yield, and improve environmental compliance. The project is structured around four key innovation areas:
- Additive Manufactured (AM) Metallic Patches and Coatings
Designed to reduce cavitation damage and improve component resistance and longevity. - New Strategies for Rotational Speed Adaptation
Drawing on recent advancements in power electronics, this approach investigates adjusting turbine rotational speed during low-flow conditions to reduce fatigue during deep part-load operation. While speed variation is generally more associated with head variation, this study explores its impact on flow dynamics and unit stability—without requiring a full power converter. - Advanced Air Injection Systems
Aimed at improving part-load operation and increasing dissolved oxygen levels downstream of the dam, this innovation involves injecting air at multiple points within the turbine. The research identifies optimal injection locations and quantities to maximise benefits, offering new insights into fluid dynamic behaviour. The outcome will be a comprehensive toolset to assess which air injection technologies most effectively enhance hydraulic efficiency and extend fatigue life. - New Runner Designs Adapted to Environmental Flows (E-Flows)
Developed to improve performance across the entire operational range (0–100%) without the need for civil works, enabling cost-effective upgrades through runner replacement alone.
To evaluate these solutions, SHERPA will develop digital modelling tools, simulation platforms, and real-time monitoring systems. These systems will utilise live sensor data to assess vibrations, detect damage, and predict turbine performance under off-design conditions. In essence, this digital twin—integrated with a fatigue calculator—will be capable of estimating residual service life based on both statistical analysis and unit-specific data:
- By leveraging trends and statistical datasets;
- By establishing digital twins using actual geometry and operating data from the hydropower units.
Pilot Projects in the Sil and Mediterranean Basins
To address all relevant technical aspects and assess mitigation measures for deep part-load operation, Iberdrola is offering a variety of pilot sites featuring different plant designs and commissioning years. These sites present a range of operational challenges, enabling the identification of scalable solutions and the extrapolation of model parameters for broader application.
With the SHERPA project now underway, the consortium is committed to addressing these critical issues and achieving the most impactful results possible in this ambitious European initiative.
