WP2 was concerned with the design and optimization of the selected two different pump-turbine concepts, using CFD validated with model scale tests and computational evaluation of fish impacts to be expected in terms of injury and mortality. The prototype mode switching times for pump to turbine mode and turbine to pump mode were estimated to 110 s and 107 s, respectively, while keeping unfavorable load gradients limited. It was shown that the PD-RPT may provide a hydraulic round-trip efficiency of up to 75% in large model scale. The experiments with the PD device also showed the vulnerability of this device for debris particles in the water flow, which easily blocked the small opening gaps between the rotors and the casing. For both kinds of devices, the mechanical loads were not an issue. It is proposed that precautions are taken to install fish screens to divert fish passage through the units.
The objectives of WP3 were to design and develop a Power Take-Off (PTO) powertrain architecture with multidimensional machine-side control to maximise efficiency and minimise the mode switching time of the Reversible Pump-Turbine (RPT) concepts over a wide range of operating conditions. The optimized PTO, control and grid interface have been implemented for both a full-scale (10 MW) design and a small (50 kW) physical model. The dry-test setup and validation of the PTO and control architecture was done in Kortrijk; validation was done on the wet test-setup (with the CR RPT) in the hydraulics laboratory in Braunschweig.
WP4 had as objectives to provide measurement results from the laboratory experiments of the complete model scale machine set (turbine and PTO). The measurement results were to be used for validation of the machine performance models in turbine and pump operation, validation of structural models and for the assessment of fish behavior. The characterization tests of the CRPT device confirmed high operating efficiencies of 87% and 92% at the Best Operation Point (BEP) in turbine and pump mode respectively. Furthermore, operation in turbine mode demonstrated efficiencies of over 80% for a wide range of operation, which was possible due to the use of multiple speeds and speed ratios between runners.
The WP5 objectives aimed at the site identification for potential low-head pumped storages along the coasts of the North and Baltic Seas. A GIS tool has been developed to support identification of potential sites, providing information on other use and spatial functions in the area. An overview of legal, regulatory and environmental procedures has been reported for a number of countries. Robust design of basins and civil structures (resistant against saltwater, weathering, fatigue), service life assessment and estimated civil costs were included in this WP. Machine related structures adopted to fatigue actions and chemical exposure were designed and the necessity of fish screens in addition to fish friendly pump/turbines as preferred technological option was evaluated. For a 200 MW/2 GWhr ALPHEUS implementation, construction costs are estimated at 2,0 billion euro with a Levelized Cost of Storage (LCoS) of 508 euro/MWh; for a 2 GW/20 GWhr implementation these costs are estimated at 9.2 billion euro, with a LCoS of 268 euro/MWh.
The WP6 objectives consist of addressing the potential contribution of pumped storage flexibility of an ALPHEUS system to grid stability and to evaluated the economic potential of an ALPHEUS storage system. The key aspect of the first task, the evaluation and identification of potentials and the associated challenges of the ALPHEUS pumped hydro storage system in its role in providing ancillary services for a contribution of pumped storage flexibility to grid stability, was implemented by a discussion on specific topological and site-related implications and resulting possible advantages for long- and short-term stability effects. Based on this historical grid analysis, it was determined that under the present market, a 2GW/20GWhr ALPHEUS plant could generate an annual revenue of 186 million euro on the day-ahead trading market. The investigation showed that both grid services have the potential to deliver sufficiently high revenue for a viable plant construction.
The objectives of WP7 were the implementation of the tasks Communication (To provide information about the project, Dissemination (To enable the use of project results) and Exploitation (To ensure uptake of project results during and beyond the project. At the beginning of the project, we set a target for the dissemination to reach an audience of 10k people across the duration of the project, it can be said that this target was achieved thought a multi-channel and multi-media dissemination strategy and thanks to the efforts of all the partners. The website has reached a total of almost 20,000 unique visitors over the 4 years of the project while official publications have been read a thousand times in total. Our online presence across professional networks such as LinkedIn and ResearchGate has reached a further few thousand people.
