What is Solar Energy?
·In solar system Earth's nearest star is the Sun and sun is constantly releasing energy. The Sun act as a huge nuclear furnace, the heat and pressure combine with hydrogen atoms together to form helium and release the large amounts of energy ,so that sun look brighter. The energy produced by this nuclear fusion reaction comes to Earth in the form of radiation like the ultraviolet light that causes sunburns and infrared radiation that cause as heat.
How Is Sunlight Turned into Electricity?
Continuous solar heating isn’t the only way to get energy from sunlight.Photovoltaic cells sometimes called solar cells—can turn sunlight directly into electricity. Sunlight striking the different layers of metal in a solar cell causes electricity to flow. Any electricity produced by a solar cell can be thought that it is free of cost· ,like example either the battery you don't need for your calculator.
A Renewable Source of Energy
Solar energy is a renewable resource. A renewable resource is a unlimited supply, where we get continuously which may use for longer time.As long as the Sun shines, solar energy is available. Power plants that rely on burning coal or gasoline are using nonrenewable resources. A nonrenewable resource is one that is only found in limited supply and which may run out.
At the center of our solar system is a massive star we call the sun. This giant ball of hot gas radiates intense light and heat. The planets close to the sun, Mercury and Venus, reach scorching temperatures. Planets farther from the sun than earth, such as Mars, Saturn, and Pluto, exist in frigid temperatures. But here on earth, about 93 million miles from the sun, the planet receives just enough heat and sunlight to support life.
Temperatures on earth can vary too, depending on the time of year, the location, and even the time of the day. We experience seasons because the Earth tilts on its axis as it revolves around the sun. In the summer, the northern hemisphere tilts towards the sun as the southern hemisphere tilts away from the sun. The opposite happens in the winter. No matter what time of year, places along the earth’s equator receive the most heat from the sun.
Nuclear energy
Some power companies use nuclear energy to generate electricity. Nuclear energy is released by splitting atoms. This energy creates heat, which passes water over to make steam. In turn, this steam turns turbines to create electricity. This form of energy can be very efficient and clean, but it can also be dangerous. One problem is that the nuclear waste does not go away. There’s also a chance that radioactivity can accidentally be released into the environment.
The Power of Atoms
Nuclear power is a rich and renewable source of energy. About 1 kg of deuterium, a type of hydrogen that’s used as a nuclear fuel, can produce as much power as 3 million kg of coal. Nuclear power plants do not have unwanted emissions like fossil-fuel power plants, but they do produce a very dangerous waste product. Nuclear waste is highly radioactive and needs to be carefully stored. This is an expensive process and any errors can have catastrophic consequences.
When you look at all the fuel sources available today, you can see that there isn't any “perfect” fuel source — one that is cheap, wastes very little energy, and produces no unwanted side-effects. This makes it all the more important to conserve the fuel sources we have and to use them wisely.
Comparing Fuels
With all these fuel options, how do you know which ones are most efficient? That is, how do you know which fuels produce the most useable energy, with the least amount of waste? The problem with comparing barrels of oil with tons of coal with millions of cubic feet of natural gas is that they are all in their own units of measurement.
The way to make a meaningful comparison is to convert all of the different units to the same unit. Scientists have a measurement for making energy comparisons: the BTU, or British thermal unit. This is a measurement of a fuel’s energy content, the amount of heat it’s capable of producing. One BTU equals the amount of energy needed to raise the temperature of one pound of water by one degree Fahrenheit, when the water temperature is about 39 degrees F. (It’s also the same amount of energy created when you burn a kitchen match.) A ton of coal consists of 28,000,000 BTUs — which means it can raise the temperature of 28 million pounds of water by 1 degree. The energy content of 1,000 cubic feet of natural gas is over 1 million BTUs.

The BTU measurement provides a useful way of evaluating the amount of energy consumed in your home and allowing you to compare how much energy you can get out of different energy sources

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