As fossil fuels become scarcer and their effects take a greater toll on the environment, the need for a renewable less polluting energy source is being felt. One of the most obvious and abundant answers is using a combination of water and gravity to create electricity. This harnessing of falling water has been used for around 2500 years, ever since the Ancient Greeks did it.
Obviously, the Greeks did not use the water the to create electricity. They had no turbines, generators or power lines. These days, we do have those things. The basic idea behind a hydroelectric dam is to stop water and limit the flow of a river. This is accomplished more or less by a big wall. The wall contains a hole in the middle, called an intake hole or valve. The intake is regulated by a control gate. The gate can be raised or lowered to allow more or less water through. The amount of water directly influences the amount of force that spins the turbine that waits at the bottom of the penstock, which is basically a tube. After the spinning, the water keeps moving through the outflow, which is on the other side of the dam. The water then becomes the rest of the river, and continues flowing downstream. .
When the water spins the turbine, or rather the blades attached to the turbine, a series of magnets also spins inside the generator. The magnets rotate past copper coils, producing alternating current (AC) by moving a bunch of electrons. The AC then runs .
through the plants" transformer, which turns the electricity into a source of higher voltage. The electricity is then sent out in power lines to wherever it is needed. .
The primary environmental impact concerns associated with hydroelectric dams does not tie into output of harmful chemicals, but more so the effects the dam has on the river it is built on. .
First all, the flow of the river is severely limited by the dam. This creates a large flooded area, called a reservoir, which changes the ecosystem of the surrounding area.