INTRODUCTION

Hydroelectric power (often called hydropower) is considered a renewable energy source. A renewable energy source is one that is not depleted (used up) in the production of energy.  Through hydropower, the energy in falling water is converted into electricity without “using up” the water.

Hydropower energy is ultimately derived from the sun, which drives the water cycle. In the water cycle, rivers are recharged in a continuous cycle. Because of the force of gravity, water flows from high points to low points. There is kinetic energy embodied in the flow of water.

FIGURE 1 : THE CYCLE OF WATER 

HOW ELECTRIC POWER SYSTEM WORKS?

PART1

Flowing water is directed at a turbine (remember turbines are just advanced waterwheels). The flowing water causes the turbine to rotate, converting the water’s kinetic energy into mechanical energy.

FIGURE 2 : FLOWING WATER TO TURBINE

FIGURE 3 : HOW HYDROPOWER PLANTS WORKS

The amount of electricity that can be generated by a hydropower plant depends on two factors :

FLOW RATE = the quantity of water flowing

When more water flows through a turbine, more electricity can be produced. The flow rate depends on the size of the river and the amount of water flowing in it. Power production is considered to be directly proportional to river flow. That is, twice as much water flowing will produce twice as much electricity.

HEAD : The height from which water falls

The farther the water falls, the more power it has. The higher the dam, the farther the water falls, producing more hydroelectric power.

Power production is also directly proportional to head. That is, water falling twice as far will produce twice as much electricity.

TYPES OF HYDROPOWER

FIGURE 4 : DAM WITH HIGH HEAD

Tall dams are sometimes referred to as “high-head” hydropower systems. That is, the height from which water falls is relatively high

FIGURE 5 : DAM WITH LOW HEAD

Many smaller hydropower systems are considered “low-head” because the height from which the water falls is fairly low. Low-head hydropower systems are generally less than 20 feet high.

FIGURE 6 : IMPOUNDMENT SYSTEM

An impoundment is simply a dam that holds water in a reservoir. The water is released when needed through a penstock, to drive the turbine.

This illustration shows the parts of a standard hydroelectric dam. Most large, high-head hydropower facilities use impoundments. 

FIGURE 7 : A RUN-OF-THE-RIVER SYSTEM

A run-of-the-river system uses the river’s natural flow and requires little or no impoundment. It may involve a diversion of a portion of the stream through a canal or penstock, or it may involve placement of a turbine right in the stream channel. Run-of-the-river systems are often low-head.