A comprehensive review of novel technologies for hydropower and strategic opportunities for Europe

This paper reviews recent developments in hydropower technologies, focusing on their role in improving operation, monitoring, performance, and sustainability within modern power systems. It examines how innovations in electro-mechanical equipment and digital tools, supported by the regulatory frameworks that drive the modernization and development of hydropower, can be exploited in the EU. The study explores the potential of small- and ultra-low-head installations, including gravity-based, hydrokinetic and impulse turbines, addressing their recent innovations and scalability potential. Environmental issues are addressed through fish-friendly designs, oil-free operation, and adaptive flow management. Pumps operating as turbines in reversible modes are addressed as key equipment for pumped storage hydropower, enabling flexibility and distribution. Variable-speed operation, enabled by Fully Fed Frequency Converters and Doubly Fed Induction Machines, is discussed to enhance performance and conversion efficiency under variable flow. Digitalization trends are analysed through digital twins, artificial intelligence, and machine learning, supporting predictive maintenance, real-time monitoring, and system analysis. Challenges are also discussed: implementation barriers include sensor reliability, cybersecurity, and integration complexity. The role of EU policies in guiding sustainable energy development and environmentally compliant hydropower deployment is examined, showing as new technological innovation, supported by a scientific assessment of its potential in the European context can support renewable energy integration, competitiveness and resilient power systems. • The paper reviews emerging hydropower technologies. • Innovative designs, AI, machine learning and digital twins support advanced optimization. • Digitalization enhances plant reliability and sustainability, but there might be cybersecurity risks. • New environmentally enhanced turbines improve sustainability. • Opportunities and challenges for the European context are discussed and assessed.