Climate change mitigation strategies require a high share of renewable energy sources (RES). The variable generation of RES requires that new hydropower technologies provide greater flexibility over an extended range of hydraulic conditions.
Some of the most salient flexibility technologies under development are: stabilizer fins, an adjustable diaphragm installed in the draft tube cone, J-grooves, air injection/admission, axial water injection with high/low velocity and low/high discharge, tangential water injection at a cone wall, axial water injection with a counter-flow tangential component, ejector power plants for the excess flow rate, two-phase air-water injection along the axis, hydroelectric energy storage solutions, battery hybrids, and smart modeling and control solutions to increase unit flexibility and operating range.
The collection and processing of real-world data to adjust the actual working conditions of hydropower turbines can provide advanced grid supporting services without compromising stations’ reliability and safety. It is estimated that a total of 42 TWh could be added to present hydropower energy production by implementing hydropower digitalization. Such an increase could lead to annual operational savings of USD 5 billion and a significant reduction of greenhouse gas emissions.
Pelton Turbine Generator
With the aim of compensating the increase of variable RES in power systems, energy storage such as that provided by pumped hydropower storage (PHS) is needed. PHS plants operate both in turbine and in pump mode for peaking regulation, which can be enhanced by fixed or variable speed turbines. Speed variation is possible thanks to the use of electronic converters, in either of the two following ways: converter-fed synchronous machines, i.e. synchronous machines whose stator is driven with a variable frequency; and double-fed induction machines, i.e. electric machines that are fed by AC currents into both the stator and the rotor windings.
Due to environmental concerns about hydropower, the sustainability of a plant is increasingly considered at the design stage. Fish-friendly turbines today include Archimedes hydrodynamic screws, water wheels and Vortex turbines for low head applications, as well the Alden turbine and the minimum gap runner turbine for higher heads.