energy from sun: energy radiated from the Sun in the form of heat and light, used by green plants for photosynthesis and harnessed as solar power
2.
energy from Sun: energy obtained from radiation emitted by the Sun
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Wind Energy Basics

Basic information on wind energy and wind power technology, resources, and issues of concern.
Wind Energy and Wind Power

Wind is a form of solar energy. Winds are caused by the uneven heating of the atmosphere by the sun, the irregularities of the earth's surface, and rotation of the earth. Wind flow patterns are modified by the earth's terrain, bodies of water, and vegetative cover. This wind flow, or motion energy, when "harvested" by modern wind turbines, can be used to generate electricity.
How Wind Power Is Generated

The terms "wind energy" or "wind power" describe the process by which the wind is used to generate mechanical power or electricity. Wind turbines convert the kinetic energy in the wind into mechanical power. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity to power homes, businesses, schools, and the like.
Wind Turbines

Wind turbines, like aircraft propeller blades, turn in the moving air and power an electric generator that supplies an electric current. Simply stated, a wind turbine is the opposite of a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity.
Wind Turbine Types

Modern wind turbines fall into two basic groups; the horizontal-axis variety, like the traditional farm windmills used for pumping water, and the vertical-axis design, like the eggbeater-style Darrieus model, named after its French inventor. Most large modern wind turbines are horizontal-axis turbines.
Turbine Components

Horizontal turbine components include:

* blade or rotor, which converts the energy in the wind to rotational shaft energy; * a drive train, usually including a gearbox and a generator; * a tower that supports the rotor and drive train; and * other equipment, including controls, electrical cables, ground support equipment, and interconnection equipment.

Wind turbine diagram - click for enlarged image.

Hydro Energy

Hydro energy is simply energy that is taken from water and converted to electricity. Hydro energy can be obtained by using many methods of capture. The most common method of using energy from water is a hydroelectric dam, where water coming down through an area causes turbines to rotate and the energy is captured to run a generator. Power can also be generated from the energy of tidal forces or wave power, which uses the energy created by waves.

Many countries in the world use hydro energy for conversion to electricity. Canada maintains the highest use, while the United States comes in second. One of the main reasons that hydro energy is used is that it is a renewable energy, meaning it will not be depleted over time and it will consistently be replenished. It is also a clean energy source, as it does not emit any toxins.

One downside to using hydro energy is that it can sometimes change the natural flow of the water which can make it possible to harm plants and animals in the water. It can also damage areas and wildlife, as when creating a hydro electric dam, areas must be flooded.

Other reasons that many want to use hydro energy is that it is cheaper than using other methods to convert energy to electricity. It is also reliable and can be used almost immediately when turned on to meet the demand for electricity. Therefore, one must weigh the pros and cons before deciding to use hydro energy to supply their demand for electricity.