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Hydroelectricity is based on harnessing the power of water to produce electricity. With around 16% of global electricity production (more than 4,000 TWh/year), it is one of the main sources of renewable energy today. Its technical potential is estimated at 15,000 TWh/year, but its development is limited by geographical, environmental and socio-economic constraints.
Hydropower capacity by country, 1898 - 2023. Source: VisualizingEnergy
Hydroelectricity is based on the conversion of the kinetic energy of water into mechanical energy and then into electricity via turbines and alternators. The process includes several key steps :
1. Water capture : a dam is built on a watercourse to create
a reservoir, accumulating potential energy.
2. Flow control : water is released in a controlled manner to turbines.
3. Energy conversion : water in motion makes turbines turn,
transforming kinetic energy into mechanical energy.
4. Electricity generation : the turbines are connected to generators
that convert mechanical energy into electricity.
It exists several types of installations :
- Power plants along the river exploit the natural flow of rivers without storage
of water. It exists two ways to exploit the potential power of water in this case,
via the difference in level between the water intake and its return point (central
“of high fall”), adapted to strong differences in altitude, either via the water flow (“power plant of
low fall”), adapted to large flows but slight differences in altitude.
- The lock power plants have a small storage capacity that allows
daily or weekly modulation.
- Lake power plants, equipped with large reservoirs, offer flexibility
important.
- Pumped energy transfer stations (STEP) store energy in
pumping water to an upper reservoir during periods of low demand
and release it to produce electricity during peak consumption.
Hydroelectric turbine technologies are evolving to suit a variety of applications. The turbines francis and Kaplan are widely used in large power plants and turbines Pelton effective for high falls of water. Of micro turbines And hydrokinetic systems make it possible to produce energy without dams, directly exploiting the flow of watercourses. Les Archimedes screw turbines, designed for low fall heights, are particularly respectful of aquatic fauna.
Hydroelectricity is a renewable and carbon-free energy that emits almost no no greenhouse gases once the infrastructure is in place. It offers a stable production and pliable, and can provide electricity continuously while adapting to changes in demand. In addition, it is an efficient energy storage, in particular thanks to WWTPs.
Nevertheless, hydroelectricity has several drawbacks. Its ecological impact is significant, because the construction of dams changes aquatic ecosystems, affects biodiversity and can cause the displacement of populations. It is also vulnerable to climate change, since Variations in rainfall and droughts influence water availability and electricity production. In addition, the initial cost of infrastructures is high, as their construction requires significant investments and long amortization periods.
Hydroelectric infrastructures are designed to last several decades, but they are subject to various weakening factors. Erosion and siltation, for example, reduce the storage capacity of reservoirs and alter the efficiency of turbines. Another challenge is the aging of materials: the wear and tear of concrete structures and mechanical components can require expensive renovations. Hydrological variations, caused by climate change, can lead to prolonged periods of drought or exceptional floods, putting pressure on dams. Finally, some dams located in regions with geological risks can increase the probability of earthquakes or landslides. Regular maintenance, infrastructure modernization and the implementation of risk mitigation measures are therefore essential.
Despite these challenges, hydroelectricity is key for the energy transition. The optimization of existing infrastructures, the development of solutions that have less impact on the environment and the integration of WWTPs into energy storage strategies will be decisive for its future. New technologies are emerging, such as osmotic energy, and projects are under development to meet growing demand. In addition, the integration of hydroelectricity with Wind power and The solar makes it possible to ensure the stability of electrical networks. Appropriate financing and regulations are also in place to reduce the ecological impact and improve the profitability of projects. The rise of other renewables could change the role of hydroelectricity, but its potential makes it a cornerstone of the global energy mix.