Introduction to Renewable Energy

Renewable energy may be broadly defined as energy that is of unlimited supply, such as solar, wind and geothermal energy. The origin of the source of this energy can be traced back to the sun (solar or wind energy) or the gravitational effects of the sun and moon (tides). Given the source, in effect, the source of energy is inexhaustable.

The challenge with this unlimited source of energy, is the conversion into more useful forms of energy, such as electricity which powers our appliances, stereos, lights, and a plethora of other items requiring electricity. The manner of conversion of this energy from the sun are few, and the prominent methods are mechanical devices such as wind turbines which convert the kinetic energy of the wind into electrical energy, or photovoltaic cells to convert solar energy directly into electrical energy.

Wind Energy

Wind turbines extract the energy from the wind by transferring the momentum of the air passing through the wind turbine rotor, into the rotor blades. The rotor blades are aerofoils which act similarly to an aircraft wing. The modern wind turbine is a very efficient device for concentrating the energy in the air flow, into a single rotating shaft. The power in the shaft can then be used in any way. Historically it was used for grinding or water pumping but the large machines of today convert the shaft power into electricity.

The Danish Wind Industry Association possesses an excellent tutorial on all aspects of wind turbine mechanics, design and concepts. The piece is entitled "Guided Tour on Wind Energy" and can be reviewed by clicking on the title highlighted earlier.

Solar Energy

Diagram depicting the principles of solar energy coversion to electricity. Click to enlarge

In order to capture the solar energy produced and convert to electricity, two components are required: a) collectors; b) storage. A collector simply collects the radiation that falls on it and converts that into electricity. Typically, the individual components capturing the solar energy are called "solar cells", and these are then combined into an array structure known as "photovoltaic" panels. These panels are often installed on roof-tops, or atop tower-like structures, the best installations having tracking devices to ensure that the angle at which the panels capture solar energy is optimum.

For more details on the subjects of wind and solar energy, click wind energy and solar energy for more details than you can shake a stick at.