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The two types of energy are renewable and non-renewable

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There are a variety of ways that we generate energy to power our modern world, many of which people have used for hundreds or even thousands of years. Some of these are considered renewable, like wind and sunlight, which means that we are not in danger of running out of them. However, some sources are being consumed much faster than they are being created, such as coal, which means that we will someday run out of that energy source.


Non-renewable energy sources are used up faster than they can be replaced

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Non-renewable energy sources include coal, petroleum, and natural gas. These three energy sources are called “fossil fuels” because they are created by ancient living things, like plants and animals, that were buried in the ground millions of years ago. After long periods of time under intense pressure and heat, these ancient living things change into fuels like coal and petroleum. Because it takes millions of years to create coal or petroleum, we use them up much faster than new coal or petroleum is created. That’s why they are called “non-renewable”. Non-renewable resources are the primary source of energy in the world today.


We get power from fossil fuels by burning them

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We extract energy from fossil fuels by burning them, such as burning gas to run a car or burning coal to generate electricity at a power plant. Fossil fuels are extremely flammable and create a hot flame. When the fuels are burned, heat is generated. This heat is used to heat water, which in turn creates steam. The steam is used to turn turbines. These turbines turn generators, which create energy that we can use.

When these fuels are burned, they create various gases called emissions. Large amounts of these gases create pollution. In addition to their limited supply, the pollution they create is the largest downside to fossil fuels. If you have heard of the terms “climate change” or “global warming”, you may already know that burning fossil fuels are among the causes of pollution that create climate change. Climate change refers to long-term changes to the weather we experience, for example more frequent droughts or more frequent severe weather.


Nuclear energy uses the power of atoms to create energy

Nuclearenergybycountry Source: International Atomic Energy Agency, March 2015
Atoms are the smallest division of life. Everything in the world is made up of atoms. Each atom has a central particle called a “nucleus”. Nuclear energy gets its name from the fact that the power comes from the nucleus. We produce nuclear energy by splitting uranium or plutonium atoms in a process called nuclear fission. When these atoms are split, the action releases a huge amount of energy. The heat created from this process is then turned into steam, which is used to turn turbines. The percent of energy production by harnessing nuclear energy varies widely by country, as the table shows.

Nuclear fission processes occur in a special structure in a nuclear power plant, called a “containment structure”, which is designed to keep dangerous radiation from escaping the plant. Nuclear processes generate something called nuclear waste. This consists of the leftovers after nuclear fission. This radioactive waste is dangerous to people and animals, and has to be carefully disposed of.

Every once in a long while, there are accidents of some kind at nuclear power plants. Past examples include the failure of the Fukushima power plant in Japan after the 2011 earthquake and tsunami, an accident in 1979 at the “Three Mile Island” power plant in the US, and the Chernobyl power plant in Russia in 1986. Each of these resulted in radioactive material released into the surrounding environment. Because of the danger of nuclear accidents, some people do not like nuclear power generation. Japan generated 30% of their power via nuclear power plants before the Fukushima accident; now Japan is largely against nuclear power, and produces less than 2% of its energy through nuclear power.


Renewable energy sources are not used up

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Renewable energy sources are considered the best for the environment since nothing from nature has to be destroyed or used up. Renewable energy is growing and expanding, but is still not close to fossil-fuels in their use. About 19% of the energy used in 2014 came from renewable resources. Some countries are using much more renewable energy than others, as the table on the right shows. Often when the prices of fossil fuels increase, the use of renewable energy grows. Some examples of renewable energy sources are solar power, hydroelectric power and wind power. These are each described below.


The power created by the sun is called solar power

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Solar power uses the power of the sun's light to create electricity. This energy is collected through solar panels. Solar panels are made up of a large number of solar cells. These cells help focus the sun’s energy and transform this into usable electric energy. Many solar panels are placed over a large area to create solar arrays. These are angled at a position to get the most out of the sun’s rays and be facing the sun at the most times during the day.

In addition to large arrays people are installing solar panels on their homes and businesses. This allows people to create their own power and not have to purchase it. However, solar panels are not cheap and require a lot of money to install them in the first place.


Power created by water is called hydroelectric power

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Hydroelectric power refers to making electricity from the power of water in motion. For example, water flowing over a man-made dam falls downward due to the force of gravity (the same reason a ball falls down if you throw it in the air). The power in this falling water can be used to turn turbines at the bottom, which can generate electricity through a process called electromagnetic induction.

This is the most widely used form of renewable energy. However, it does have its disadvantages. Hydroelectric power requires bodies of water to be damned up. This effects the ecosystem and animals living in the area. It impacts their movement within the body of water. In addition, if a region is experiencing a drought – an uncommonly dry year or years – then they may no longer be able to generated as much power using hydroelectric dams, as there may be much less water available.


Wind power is collected by wind turbines

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We are able to harness the power of wind by using large wind turbines and windmills to generate electricity. These turbines are set up in wind farms in large open areas consisting of up to thousands of turbines. They are positioned to be facing the most common direction of the wind and slowly turn as the wind blows. There are even windfarms being set up in the ocean to take advantage of strong ocean winds and not affect large open landscapes.

Although wind power is one of the cheapest forms of energy, the amount of wind in an area is not consistent and predictable. Since wind is variable force the amount of energy it generates is also not consistent.


Turbines are key to power generation

You may have noticed a common theme in this section. Power generation comes about often by turning turbines. These turbines may be turned by steam, by wind, or by water. And the steam could result from burning a fossil fuel or creating a nuclear reaction. But the result in any case is that a turbine is turned. And, turning a turbine can generate electricity through a process called electromagnetic induction - a topic for another section.


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