Hydroelectric power is a form of renewable energy that uses the potential energy of water at a high level to generate electricity. Being a source of renewable energy hydroelectric power doesn’t generate any greenhouse gasses or air pollution. In this post, we will explore how hydroelectric power plant layout and its working, what are their advantages and disadvantages, how to select suitable sites for them, and what are the different types of hydroelectric plants.
Selection of Site
- A huge quantity of water should be available.
- The available water should be at the good head.
- Land should be available at a reasonable price.
- The site should allow a strong foundation with minimum cost.
- The site should be easily accessible for an equipment transportation facility.
Classification of Hydroelectric Power Plant
According to the Availability of Water
- Run-off River Plant: There are two categories of run-off plants. First is the run-off river plant without pondage. These plants don’t store water. The plant uses water as it comes. The generating capacity depends on the rate of flow of water during the rainy season. Another type is a run-off river plant with pondage. Pondage permits the storage of water during off-peak periods and uses it during peak periods.
- Reservoir Plants: These plants have a reservoir to store large quantities of water. Such a big size reservoir permits carry-over water storage from the rainy season to the summer season.
According to Available Head
- Low Head: Water head of 10m or less.
- Medium Head: Water head between 10m and 100m.
- High Head: Water head more than 100m.
According to the Nature of the Load
- Base Load: A Base Load hydroelectric power plant provides a steady and continuous supply of electricity to meet the basic demand for power. It is designed to meet the minimum demand for electricity and operates at maximum output.
- Peak Load: A Peak Load hydroelectric power plant is a type of power plant that only runs when there is a high demand for electricity. It is used to provide additional electricity during times of high demand.
- Pump-Storage for Peak Load: A Pumped Storage Plant is a type of power plant that can both generate electricity and store energy. It has two ponds, one at a high level and one at a low level. When there is a low demand for electricity, the plant uses power from the grid to pump water from the lower pond to the higher pond. When there is high demand for electricity, the water from the higher pond is released and flows down to the lower pond, driving turbines and generating electricity. In short, a Pumped Storage Plant helps balance the supply and demand for electricity by storing energy when demand is low and releasing it when demand is high.
Hydroelectric Power Plant Layout and Working
The major components of the hydroelectric power plant are the reservoir, dam, Inlet gate, Surge Tank, Penstock, and Water Turbine as shown in below hydroelectric power plant layout. The Hydroelectric Power Plant Components post has a detailed description of these elements. Working of hydroelectric power is very simple, the water from the river gets stored in the reservoir. There is a dam which increases the level of water in the reservoir. From Reservoir, water starts flowing downward in penstock via the inlet gate and flows directly towards the water turbine. The force of moving water drives turbine blades and causes rotation of the turbine (The turbine harness this kinetic energy of moving water). There is a governor/generator connected to the turbine which converts the turbine’s rotational energy into electric energy. The generated electric energy is transmitted to the powerhouse via transmission lines.
Hydroelectric Power Plant Advantages
- The life cycle of hydro plants is more than 50 years.
- They do not require fuel like coal, gas, diesel and etc.
- Due to no fuel requirement, the operation cost is low
- There are no sand-by losses in hydroelectric plants.
- The maintenance cost of a hydroelectric plant is very low.
- With age, there is no reduction in the efficiency of plants.
- These plants are free from air pollution, unlike Gas Turbine Plants.
- Located in a remote area due to which land availability at a low cost.
Hydroelectric Power Plant Disadvantages
- Unlike Diesel Power Plant the designing of the hydro plant is complex and results in high installation costs.
- The generation of power depends on the quantity of water available.
- The installation and completion time is long.
- For low-capacity hydro plants, steam plants are required for backup.
- Transmission cost is high – as hydroelectric power plants are located very far from consumers.