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Fossil fuels are the most common energy source, but their finite supply and environmental impact have led to the development of alternative sources. Nuclear fission, hydroelectric, solar, and wind energy are among the most popular renewable sources, with wind energy being considered a major contributor to national energy needs in some regions.
There are myriad sources of energy available to human beings, from the most basic forms of exploiting our natural environment, to cutting-edge technological forms capable of generating immense amounts of energy. Different sources of energy are preferable for different reasons, ranging from environmental concerns, to cost savings, to what is available in a given area. The following are some of the more common energy sources used in the modern world.
The most common energy sources on the planet in modern times are those that use fossil fuels to generate their energy. Over 85% of all primary energy on earth comes from fossil fuels, and while this percentage is slowly declining, total energy consumption continues to increase. Basic fossil fuels have been used to generate power dating back before recorded history, with coal being used as fuel for thousands upon thousands of years.
In the modern world, fossil fuels power almost everything. Coal- and natural-gas-fired power plants generate huge amounts of electricity, which is distributed across countries by national power grids. Gasoline and diesel are used as primary energy sources for cars and trucks. Ships, planes, rockets, motorcycles, and just about everything else that moves uses some form of fossil fuel.
The supply of fossil fuels on the planet is, however, a finite resource and is rapidly declining, causing serious concerns about controlling steady supplies. At the same time, environmental concerns about fossil fuels are growing steadily. It is estimated that each year fossil fuels generate about 21.3 billion tons of carbon dioxide, of which only half is absorbed by natural processes. This is thought to contribute to global warming and people are suggesting alternatives as a way to get away from such polluting fuel sources.
One such alternative is nuclear fission, commonly called nuclear energy. Nuclear power plants stimulate a nuclear reaction in uranium-235, which causes its atoms to split, releasing enormous amounts of energy. This energy heats the water, which then turns into steam, which is used to turn the turbines. These turbines create electricity, which can then be moved around the country. One of the major obstacles to the mainstream adoption of nuclear power is the public perception of its dangers and the difficulty of disposing of nuclear waste.
Hydroelectric power is one of the least popular renewable energy sources available, but it is still widely used, especially in some countries. Hydroelectric generation concentrates the power contained in the slow descent of a river, building a dam or some other way to regulate the flow of water, and then using that regulated flow to turn turbines, which in turn generate electricity. Basic hydroelectricity is one of the oldest forms of renewable energy, using simple water wheels placed at strategic points in rivers to do things like grind grain. While hydroelectric power is renewable, there are environmental concerns about damming rivers.
The two most popular forms of renewable energy, and the forms on which the most attention is currently focused, are solar and wind energy. Solar energy makes use of photovoltaic cells to convert the sun’s energy into electricity or let the sunlight passively heat the air or water. Wind energy uses huge turbines, which are driven directly by the wind, to generate electricity. Wind energy is a very clean source of energy and in some regions, such as the United States, it is seriously considered as a major contributor to the national energy needs in the future.
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