How do dams generate electricity
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How Dams Generate Electricity
Hydropower as a Leading Renewable Energy Source
Hydropower is the most significant source of renewable energy, accounting for over 97% of all electricity generated from renewable sources . The primary advantage of hydropower systems is the elimination of fuel costs, making it a cost-effective and environmentally friendly energy technology .
Mechanism of Electricity Generation in Dams
Potential and Kinetic Energy Utilization
Dams generate electricity by harnessing the potential and kinetic energy of water. When water is stored in a reservoir behind a dam, it possesses potential energy due to its elevated position. This water is released through turbines, converting potential energy into kinetic energy as it flows downward. The movement of water spins the turbines, which are connected to generators that produce electricity .
Head Increaser Effect
In rivers with large head and flow variations, conventional dams often waste kinetic energy during high flows. The head increaser effect involves a Moveable Hydro-Electric Power Plant (HEPP) system where the turbine module adjusts according to the river's flow and water level. This system allows excess water to pass above and below the turbine module, creating a sub-pressure environment that increases the pressure difference between the turbine inlet and outlet, thereby enhancing electricity generation .
Multipurpose Dams and Small Hydropower Plants
Multipurpose dams, such as the Porsuk Dam in Turkey, are constructed for various purposes including domestic, irrigation, and industrial water supply, in addition to electricity generation. These dams can be retrofitted with Small Hydropower Plants (SHPs) to utilize the river's discharge capacity for electricity production. For instance, the Porsuk Dam has the potential to generate 20.69 GWh/year with a 4.2 MW installed capacity . Similarly, other multipurpose dams in Turkey have been identified for their potential to generate significant amounts of electricity with minimal new civil works .
Environmental and Economic Considerations
Retrofitting Existing Dams
Retrofitting existing dams to generate hydroelectricity involves modifying structures such as embankments or spillway bays. While the construction stage is the major contributor to environmental impacts, strategic planning and the use of new materials can mitigate these effects. For example, in Nigeria, retrofitting options have been evaluated for their environmental impacts, with the embankment option being the most viable despite its higher material and energy costs .
Floating Photovoltaic Systems
To address water loss due to evaporation and enhance electricity generation, floating photovoltaic (FPV) systems can be installed on dam surfaces. These systems not only generate solar power but also conserve water by reducing evaporation. For instance, the Demirkopru Dam in Turkey could generate 3,328.33 GWh annually with a 2.03 GWp FPV system, while preventing significant water loss .
Conclusion
Dams generate electricity by converting the potential and kinetic energy of stored water into mechanical energy through turbines, which is then transformed into electrical energy by generators. Innovations such as the head increaser effect and the integration of FPV systems can enhance the efficiency and environmental sustainability of hydropower. Retrofitting existing multipurpose dams offers a cost-effective way to increase electricity generation while minimizing environmental impacts. As the demand for renewable energy grows, optimizing the use of dams for electricity production remains a crucial strategy.
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