http://www.kidwind.org/lessons/BBrenewableenergy.html. Renewable Energy W hat is Renewable Energy?
What is Renewable Energy?
A source of energy would be considered renewable if it is a natural resource on earth and it can be naturally replenished on a relatively short time scale. Furthermore, producing electricity from renewable sources will not produce harmful pollutants or emissions and will not harm ecosystems. Renewable Energy is also called "clean" or "green" power.
Fossil fuels like coal, oil, and natural gas are nonrenewable, because they are finite resources which will run out. Fossil fuels are also environmentally harmful to extract and convert into usable energy. They produce a lot of hazardous emissions and pollutants that contribute to climate change and can harm plants, animals, and humans. Nuclear power is also considered nonrenewable because of the toxic waste it creates.
Renewable energy can be produced using sources like the wind, sunlight, hydrogen, geothermal energy (heat from inside the earth), biomass (energy from plants), flowing rivers, and even the power of the ocean!
Believe it or not, the source of most forms of renewable energy can be traced back to the sun! Solar energy is the most direct use of the sun: sunlight is used to excite electrons and push them through a circuit. Wind energy relies on the sun too! Wind is created by uneven heating of the earth's surface. When sun hits one part of the earth more directly, it warms that part up. The warm air rises and cooler air rushes in, creating wind! So wind energy is actually a form of solar energy too! Of course, energy from biomass relies on the sun too, because plants cannot grow without sunlight! Even hydropower would never work without the power from the sun!
Why Don't We Use More Renewable Energy?
The use of renewable energy is increasing at very fast pace, but we cannot rely exclusively on renewable energy to meet all of our demand for electricity. Renewable energy is not easy to store or save, because we can only get wind energy when the wind is blowing or solar energy when the sun is shining. Coal and natural gas power plants can store the fuel and use more when there is more demand or less when there is less demand.
Renewable energy is also usually more expensive than conventional energy sources. However, as technology for renewables improves and the cost of fossil fuels increases, renewables will become competitive or cheaper than fossil fuels
Wind Power Basics
A wind turbine is the modern advancement of the windmill. Instead of using the wind to lift water or move heavy rocks to grind seeds wind is used to turn an electrical generator to make electricity. Sometimes, students mistake our model wind turbines for a fan. While a fan uses electricity to produce wind, a wind turbine uses the wind to produce electricity!
How Wind Turbines Work
To put it simply, the wind turns the blades, which spin a shaft, which connects to a generator to make electricity. The electricity is sent through transmission lines to a substation, then on to homes, business and schools
Wind turbine blades spin because of lift, the same force that allows airplanes to fly. If the blades are all oriented in the same direction they will start to spin, just as the wind spins a pinwheel. The blades are attached to a hub, which spins as the blades turn. Most modern wind turbines have three blades. The blades and the hub together are called the rotor. As the rotor turns, it spins a drive shaft which is connected to a generator inside the housing at the top of the tower. This housing is called the nacelle. The spinning generator produces electricity. The generator inside of a wind turbine converts the mechanical energy of moving wind into electrical energy that we can use in our houses. Depending on the size of the wind turbine there may be a gearbox between the spinning rotor and the generator. This is to help the generator spin fast enough to make electricity for the grid. Generators on the large grid connected turbines spin at 1600 RPM. For more detailed information on wind turbine technology,
The amount of electricity that a turbine is able to produce depends on the diameter of the rotor and the speed of the wind that propels the rotor. The wind turbines that are manufactured today range greatly in their output capacity from as little as 100 watts to as much as 5 Megawatts—enough to power a small town! Wind Turbines are often grouped together in wind farms to produce large amounts of electricity. Some wind farms have only a coupe turbines, but the largest wind farms are made up of hundreds and hundreds of wind turbines.
Wind Energy Growth
Wind energy is the fastest growing energy source in the world. In 2007, 19,696 MW of new wind energy capacity were installed, reaching a global installed capacity of 93,849 MW by the end of 2007. This represents a 26.6% growth rate in that year alone! Global installed capacity exceeded 100,000 MW in early 2008. In the United States, the installed capacity if wind energy grew by an incredible 45% in 2007 and another 50% in 2008. The United States installed 8,358 MW of new wind energy in 2008. Wind energy is growing at this rate because the cost of electricity produced by wind energy is competitive with electricity produced by natural gas, oil, coal, or nuclear power. Also, wind energy is a clean, renewable technology that does not contribute to global warming. This makes it a healthier, more sustainable choice than other forms of electricity generation.