Hydroelectricity

Summary

Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and also more than nuclear power. Hydropower can provide large amounts of low-carbon electricity on demand, making it a key element for creating secure and clean electricity supply systems. A hydroelectric power station that has a dam and reservoir is a flexible source, since the amount of electricity produced can be increased or decreased in seconds or minutes in response to varying electricity demand. Once a hydroelectric complex is constructed, it produces no direct waste, and almost always emits considerably less greenhouse gas than fossil fuel-powered energy plants. However, when constructed in lowland rainforest areas, where part of the forest is inundated, substantial amounts of greenhouse gases may be emitte

Official source

https://en.wikipedia.org/wiki/Hydroelectricity

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Hydropeaking attenuation in revitalized rivers

Angela Lina Mark

Hydro power plants operate their turbine to match the peaks in electricity demand. This leads to strongly unsteady flow regimes downstream of the power plants outlet into the river. From an ecological point of view, those sudden starting and stopping of turbines, called hydropeaking, are unacceptable. A more restrictive operating of the turbines is not economically practicable, therefore, to counteract these unfavourable effects of hydro power plants, two types of mitigation measures have been found to be effective; structural or morphological measures, i.e. resp. a compensation basin or modifications in the river morphology. The second is analysed in the work to assess the effect of various features inside a channel on hydropeaking rates. The tested case are then compared to a real channel reach with a groinfield. The most effective morphology for this purpose is found to be a groinfield.

2018

The presence of an artesian aquifer lying under the construction site of a hydro-electrical power plant had not been considered in the design project. The foreseen excavation works could not be carried out due to a high risk of hydraulic heave of the excavation pit bottom and the entire plant had to be relocated. In the scope of this thesis, two alternative solutions to deal with the local artesian conditions are suggested. The first solution considers additional resisting shear forces coming from cohesion in clayey soils, whereas in usual design approaches for hydraulic heave problems only the equilibrium between gravity forces and seepage forces is established. Cohesion plays an important role for the stability of relatively small excavation pit widths and its beneficial effect could be used by applying a stepwise excavation process. The second solution suggests a local relief of artesian pressures in the zone of the construction site in order to temporarily create a neutralized zone until the power plant is completely built.

2020

Validation of hydraulic design of the Ritom compensation basin

Giovanni De Cesare, Jakob Siedersleben, Samuel Luke Vorlet

Based on the Water Protection Act of 2013, severe issues caused by the rapid change of water discharge (hydropeaking) must be reduced by operators of hydroelectric power plants in Switzerland. Therefore, a new generation of regulating basins is under construction. In Tesin, the Ritom hydroelectric power plant, constructed in 1921, will be modernized. The project includes a new powerhouse with three machine groups. A compensation basin with a volume of 100’000 m3 is planned in order to minimize the effects of hydropeaking. The discharge exiting the basin to the Ticino will be controlled by a regulating structure. Due to the new compensation basin, the route of the Foss river needs to be modified and new weirs have to be installed to prevent the overflow of the Foss river into the compensation basin. Figure 1 shows the planned basin and the physical model boundaries.

2019