The contribution of low-head pumped hydro storage to a successful energy transition

The pan-European power grid is experiencing an increasing penetration of Variable Renewable Energy (VRE). The fluctuating and non-dispatchable nature of VRE hinders them in providing the Ancillary Service (AS) needed for the reliability and stability of the grid. Today’s grid is reliant on synchronous generators. In case of sudden frequency deviations, the inertia of their rotating masses contributes significantly to the stabilisation of the system. However, as the modern power grid is gravitating towards an inverter-dominated system, these must also be able to replicate this characteristic. Therefore, Energy Storage Systems (ESS) are needed along the VRE. Among the different ESS, Pumped Hydro Storage (PHS) can be identified as particularly convenient, given its cost-effective implementation and considerable lifespan, in comparison to other technologies. PHS is reliant on difference in altitudes, which makes this technology only available if suitable topographic conditions exist. The ALPHEUS project will introduce a low-head PHS for a relatively flat topography. In this paper, a grid-forming controlled inverter coupled with low-head PHS that can contribute to the grid stability is introduced, emphasising its ability to provide different AS, especially frequency control, through the provision of synthetic system inertia, as well as fast Frequency Containment Reserves (fFCR)

The Contribution of Low-Head Pumped Hydro Storage to a successful Energy Transition

The pan-European power grid is experiencing an increasing penetration of Variable Renewable Energy (VRE). The fluctuating and non-dispatchable nature of VRE hinders them in providing the Ancillary Service (AS) needed for the reliability and stability of the grid. Today’s grid is reliant on synchronous generators. In case of sudden frequency deviations, the inertia of their rotating masses contributes significantly to the stabilisation of the system. However, as the modern power grid is gravitating towards an inverter-dominated system, these must also be able to replicate this characteristic. Therefore, Energy Storage Systems (ESS) are needed along the VRE. Among the different ESS, Pumped Hydro Storage (PHS) can be identified as particularly convenient, given its cost-effective implementation and considerable lifespan, in comparison to other technologies. PHS is reliant on difference in altitudes, which makes this technology only available if suitable topographic conditions exist. The ALPHEUS project will introduce a low-head PHS for a relatively flat topography. In this paper, a grid-forming controlled inverter coupled with low-head PHS that can contribute to the grid stability is introduced, emphasising its ability to provide different AS, especially frequency control, through the provision of synthetic system inertia, as well as fast Frequency Containment Reserves (fFCR)

Conceptual design of the Valmeer's pump storage station of the DELTA21 plan

It is widely known that climate change will cause sea level rise and larger river discharges in the close future (because more precipitation during a shorter amount of time will happen). In the Netherlands, the delta works were developed to protect the hinterland from sea-water during storm surge situations. The storm surge barriers close and the water is kept at the sea. However, if large river discharges are present together with storm surge, the water level behind the barriers will rise because the closed barrier won't let the river water out. In delta areas, this is a major threat to water safety. To tackle these future problems Huub Lavooij and Leen Berke came up with the DELTA21 plan.  The plan is to build a storm surge barrier together with pumps that can evacuate the water from the river in the event of having both storm surge and large river discharges happening simultaneously. As this situation will happen once every ten years on average, there is a risk that the pumps might not function when needed if they were on hold for ten years. To tackle that problem and also producing green energy, a hydro pump storage basin is proposed to take advantage of the pumps already installed for flood protection. This hydro pump storage basin is called Valmeer. As this structure would be built next to the Maasvlakte 2, in a red Natura 2000 area, some ecological value must be gained with this project in return. That is why the Getijmeer (tidal lake) was created. This tidal lake would allow opening the Haringvliet sluices and thus recovering fish migration in that area. Bringing then the ecological, recreational and economic value to the Haringvliet area, which is currently closed to the sea. The objective of this thesis is to create a conceptual design of a hydro pump storage station able to turbine water in for energy generation and to pump it out for the same purpose and also for water safety.  For designing the plant, three locations and three different alternatives were considered. Finally, a pump storage station that is also a storm surge barrier is proposed in the northern part of the DELTA21 plan, next to the Maasvlakte 2. Aspects such as constructability, affection of sediment transport to the plant, wave loading and access to the plant were taken into account for choosing the location and the most suitable alternative.  The chosen alternative was found to be a good option if special care is taken about piping protection (the structure is subjected to head differences of 23 meters) and about methods to avoid water infiltration into the building pit during the construction of the plant (the building pit's floor is at NAP -32 m).  As a part of the design, a life cycle analysis on CO2 emissions was performed. This showed that the hydro pump storage station can bring positive ecological value in terms of CO2 emissions reduction for the grid of the Netherlands. Producing energy at 280 g of CO2/kWh at present grid conditions and at -140 g of CO2/kWh if renewable energy is used to power the pumps. The conventional fossil fuel energy-producing methods do it at between 500 and 1050 g of CO2/kWh.  Therefore this thesis shows that the DELTA21 plan is not only good for flood protection but for renewable energy generation. Contributing then to the United Nations Sustainable Development Goals of "affordable and clean energy" (energy generation function) and "life on land" (water safety function).   DELTA21Civil Engineering | Hydraulic Engineerin

CFD modelling: The interaction between extreme waves and a lighthouse upon a shoal

Lighthouses are structures subjected to extreme weather conditions which have to resist strong surge. Therefore to ensure their survival over time, it is necessary to determine the loads that these structures will face during its lifetime. However, load prediction on lighthouses is troublesome due to the multiple factors that affect the loading. First, the geometries of lighthouses vary considerably from one to another, not usually representing the classic cylindrical shape by which they are modelled in laboratories. Second, climate change transforms the statistical properties of the sea states and will bring more extreme events in the near future. As so as sea level rise. Lastly, the bathymetry around a lighthouse is considerably different to the ones used to model lighthouses in labs, which can affect wave propagation and breaking. Therefore loading is affected. As the traditional physical methods are both expensive and time consuming, researchers have developed computational tools to accurately represent reality. In this report, waves2Foam (a toolbox within OpenFOAM) will be used to reproduce some tests performed on a physical wave flume. The goal is to represent the conditions of the lab in the computational model so that this model can then be used to represent different geometries and wave loads over lighthouses in an easy and cheap way. Additionally, the most of the current tests were performed with waves directly hitting the lighthouse structure. However in this study, the waves break over a shoal and then the mass of water reaches the structure. This causes a smaller maximum load but the load is applied during a longer time that when a wave breaks directly on the lighthouse. In this study the physical model performed by Piermodesto Caputo (year 2017/2018) and supervised by Professor Renata Archetti and Dr. Alessandro Antonini (co-supervisor) will be modeled using waves2Foam (OpenFOAM). The physical model was performed in Plymouth University laboratory "COAST". The goal of the model was to determine the loads that the Dubh Artach lighthouse will face in the future taking into account sea level rise and extreme weather conditions due to climate change.Civil Engineering | Hydraulic Engineering | Hydraulic Structures and Flood Ris

The contribution of low‐head pumped hydro storage to grid stability in future power systems

The pan-European power grid is experiencing an increasing penetration of Variable Renewable Energy (VRE). The fluctuating and non-dispatchable nature of VRE hinders them in providing the Ancillary Service (AS) needed for the reliability and stability of the grid. Therefore, Energy Storage Systems (ESS) are needed along the VRE. Among the different ESS, a particularly viable and reliable option is Pumped Hydro Storage (PHS), given its cost-effective implementation and considerable lifespan, in comparison to other technologies. Traditional PHS plants with Francis turbines operate at a high head difference. However, not all regions have the necessary topology to make these plants cost-effective and efficient. Therefore, the ALPHEUS project will introduce low-head PHS for regions with a relatively flat topography. In this paper, a grid-forming controlled converter coupled with low-head PHS that can contribute to the grid stability is introduced, emphasising its ability to provide different AS, especially frequency control, through the provision of fast Frequency Containment Reserve (fFCR) as well as synthetic system inertia. This paper is an extended version of the paper “The Contribution of Low-head Pumped Hydro Storage to a successful Energy Transition”, which was presented at the 19th Wind Integration Workshop 2020