Tidal Energy for Kids





We know that our planet is in danger from too much pollution. Most of the pollution is created by burning coal and oil to make electricity. When we burn these fossil fuels, dangerous gases called greenhouse gases are released into the atmosphere. These greenhouse gases are causing global warming, which is a danger to all life on Earth if we don’t get it under control. Because of this, scientists and other people are working hard to find ways to use new energy sources that won’t hurt our planet. These new energy sources are called alternative energy sources. One alternative energy source that is getting a lot of attention from scientists is tidal energy, or energy made from the ocean tides.

How Tidal Energy Works

Tidal power plant on estuary of Rance River in Bretagne, France. Image by Dani 7C3.

Tidal power plant on estuary of Rance River in Bretagne, France. Image by Dani 7C3. License: GNU FDL

To understand tidal energy, you have to know how tides work. The gravity of the sun, earth, and moon all pull against each other, which affects the way the oceans flow. Also, the rotation of our planet causes something called centrifugal force, which also puts pressure on the oceans. The combination of these gravitational pulls and the centrifugal force causes the ocean levels to rise and lower at different places during different times of the day. This is called the tidal cycle and there are two parts to every tidal cycle: the ebb and the flow. The ebb tide is the time in which the water flows out and the levels drop. The flow tide is when water flows in and the levels rise.

In order to create electricity from the tides, we build a dam-like structure, called a barrage, across the opening to tidal basins, the areas where tidal water gets deepest. Gates on the barrage open to let the rising water from the flow tide stream in and then close when it starts to flow back out with the ebb tide, trapping the water inside. Other doors in the barrage wall open and let the water flow out across turbines like those used in other hydroelectric power plants. The spinning turbines use a generator to make electricity.

Benefits of Tidal Energy

Tidal energy is a good source of alternative energy because it does not create any pollution of any kind. It is completely safe for our environment. It is also good because a high amount of energy can be captured using the tides and it does not cost much to turn it to electricity. As far as producing electricity goes, tidal energy is one of the cheapest kinds.

SeaGen, world's first commercial tidal generator. Image by Fundy.

SeaGen, world's first commercial tidal generator. Image by Fundy. License: CC BY-SA 3.0

The tides also have the potential to provide a very large amount of energy so a lot of electricity can be generated from every tidal cycle. Since the tidal cycle repeats itself every 24 hours, there is a guarantee that power can be produced this way every day of the year. It is especially great since scientists can predict when the tides will occur and how much the water level will change with each tidal cycle.

There is an extra benefit to our environment from the use of tidal energy. The barrage that is built to capture tidal energy can help protect delicate coastal areas from storm damage, as well. This is another good thing about this kind of energy. Not only does it not pollute the environment, it also can protect against erosion. This is a valuable benefit since many coastlines are in danger from too much erosion caused by severe storms.

Since the barrages don’t use any kind of fuel and only depend on ocean tides for energy, this is a completely renewable resource that has no chance of ever running out. Also, we are not using up any water when we use tidal energy. Instead, we are just catching it and releasing it so there is no danger of causing a water shortage by using this kind of energy.

Drawbacks of Tidal Energy

Just like any other energy source, tidal energy is not perfect. There are many people who are worried about whether it is safe for us to use tidal energy. It is also not something that will work in all parts of the world. One of the biggest problems with it is that it will only work in a few areas in the world. It takes a very large amount of space to build a barrage that will produce enough electricity to be work the cost. Building the barrages is very expensive compared to other kinds of power producing plants.

There are also some bad effects on the environment. Even though tidal energy does not produce any kind of pollution, the barrages completely change the coastline. Many animals and birds make their homes on the mudflats around tidal basins. When the tidal energy plants flood these areas, the habitats of these animals are destroyed. Holding the water back also causes silt to build up inside the tidal basin and can cause the released water to take longer to clear from dirt and materials. This can keep the water around the coastline from settling and becoming clear as quickly as it usually does. There is also evidence that using tidal power plants can change the migration patterns of many ocean creatures. Interfering with the normal flow of tidal cycles can also change the salinity, or amount of salt content, of the ocean water. This can have very bad effects on plant and animal life in the oceans.

Some people think tidal energy is a very good source of renewable, clean energy and that we should use it in as many places as we can. Other people think that since tidal energy plants can only produce electricity for about ten hours every day, it is not worth the danger to plants, animals, and ecosystems. The answer is probably somewhere in the middle. Tidal energy is a great resource for us to learn more about. We should explore its use but we should also be careful not to overuse it and cause damage to the very planet we are trying to save.

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