The results are the same. Take a look at this diagram courtesy of the Tennessee Valley Authority of a hydroelectric power plant to see the details:. The theory is to build a dam on a large river that has a large drop in elevation there are not many hydroelectric plants in Kansas or Florida. The dam stores lots of water behind it in the reservoir. Near the bottom of the dam wall there is the water intake.
Gravity causes it to fall through the penstock inside the dam. At the end of the penstock there is a turbine propellor, which is turned by the moving water.
The shaft from the turbine goes up into the generator, which produces the power. Power lines are connected to the generator that carry electricity to your home and mine.
The water continues past the propellor through the tailrace into the river past the dam. By the way, it is not a good idea to be playing in the water right below a dam when water is released! As to how this generator works, the Corps of Engineers explains it this way: "A hydraulic turbine converts the energy of flowing water into mechanical energy.
A hydroelectric generator converts this mechanical energy into electricity. The operation of a generator is based on the principles discovered by Faraday. He found that when a magnet is moved past a conductor, it causes electricity to flow.
In a large generator, electromagnets are made by circulating direct current through loops of wire wound around stacks of magnetic steel laminations. These are called field poles, and are mounted on the perimeter of the rotor. The rotor is attached to the turbine shaft, and rotates at a fixed speed. When the rotor turns, it causes the field poles the electromagnets to move past the conductors mounted in the stator.
This, in turn, causes electricity to flow and a voltage to develop at the generator output terminals. Demand for electricity is not "flat" and constant. Demand goes up and down during the day, and overnight there is less need for electricity in homes, businesses, and other facilities. For example, here in Atlanta, Georgia at PM on a hot August weekend day, you can bet there is a huge demand for electricity to run millions of air conditioners!
But, 12 hours later at AM Hydroelectric plants are more efficient at providing for peak power demands during short periods than are fossil-fuel and nuclear power plants, and one way of doing that is by using "pumped storage", which reuses the same water more than once. Pumped storage is a method of keeping water in reserve for peak period power demands by pumping water that has already flowed through the turbines back up a storage pool above the power plant at a time when customer demand for energy is low, such as during the middle of the night.
The water is then allowed to flow back through the turbine-generators at times when demand is high and a heavy load is placed on the system. Get a quote. The bigger the elevation and the more water that flows through the turbine, the greater the capacity for electricity generation. This completely depends on the size of the generator and the amount of potential power available at the site. In , the UK generated around 1. Hydro can be a very predictable and consistent form of electricity which works well with other forms of renewable energy to match demand.
This means that hydro is perfect for helping meet any peak demands and balance generation throughout the day. Using hydro in combination with other more weather dependent renewable generation such as wind and solar is ideal as it can be turned on very quickly and is far more responsive than gas, coal or nuclear power stations.
Hydroelectric generators also have long lives when compared to other forms of electricity generation. A hydroelectric generator can still be in service 50 to years of working and requires very little labour with low maintenance costs which makes a lot of economic sense. Yes and no. The impact that a hydroelectric project will have on the environment will vary depending on scale and technology being used — for example you can expect a much smaller impact from a small scale run-of-river hydro system than one which requires flooding of land to create a new reservoir which would have a significant impact on the ecosystem both up and downstream.
Once the work has been completed, these locations provide an opportunity for a biodiverse ecosystem to thrive. Additionally, once the water has gone through the turbines to create electricity it carries on their natural water cycle, uncontaminated and unaffected by the process of creating electricity. Hydroplants range in size from "micro-hydros" that power only a few homes to giant dams like Hoover Dam that provide electricity for millions of people.
The photo on the right shows the Alexander Hydroelectric Plant on the Wisconsin River, a medium-sized plant that produces enough electricity to serve about 8, people. Let's say that there is a small dam in your area that is not used to produce electricity. Maybe the dam is used to provide water to irrigate farmlands or maybe it was built to make a lake for recreation. As we explained above, you need to know two things:. Now all we need to do is a little mathematics. Engineers have found that we can calculate the power of a dam using the following formula:.
To get an idea what kilowatts means, let's see how much electric energy we can make in a year. Since electric energy is normally measured in kilowatt-hours, we multiply the power from our dam by the number of hours in a year. The average annual residential energy use in the U. So we can figure out how many people our dam could serve by dividing the annual energy production by 3, So our local irrigation or recreation dam could provide enough renewable energy to meet the residential needs of people if we added a turbine and generator.
Note: Before you decide to add hydropower to a dam, have a hydropower engineer review your calculations and consult with the local resource agencies to be sure you can obtain any permits that are required.
Book Navigation. How Hydropower Works Hydropower plants capture the energy of falling water to generate electricity.
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