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Solar Energy:
Solar energy is simply the energy received from our Sun. There has been much research devoted to finding ways
to harness this energy. Currently, solar power is used to either generate electricity or heat.
The process which converts light into electricity is called photovoltaic
(PV). PV panels are used for this process. These panels consist of many cells joined together. The cells come in many different forms and compositions. All of the cells in a single panel are the same. Different types of cells are used depending on the circumstances. Conversion efficiency (a measure of how well light is converted into electricity) and cost of manufacturing are the driving forces behind selecting a particular cell type. There is no need to worry about conversion efficiency since this is factored into power output of the solar panel. The most common types of cells are single crystal silicon, copper indium diselenide, poly-crystalline silicon, and amorphous silicon. Selection of which type of cell is irrelevant since power output, size, weight, quality, and cost are the important factors to consider.
There are two forms of thermal energy derived from the sun: active and
passive. Passive solar energy keeps a house warm by using special building techniques. These techniques involve the orientation of the house to gain the most direct sunlight, type and quantity of windows, thorough insulation and ventilation (R2000 is best), type of floors, positioning of curtains and so on.
This works well in the winter, but cooling can be a problem in the
summer. To compensate for this, vegetation is used to shade the house and the design must allow the prevailing winds to be used to carry excess heat away. Other factors such as reducing the window size, using reflective materials on the external walls and roof, and exhausting internal heat to the outside are some of the considerations.
Active solar energy mechanically redistributes the sun’s heat. The energy is stored in the form of heated
liquid or air. In the
case of liquid it can be used to heat your home or just the domestic water supply. Pool water heating is another efficient use of active solar techniques. When air is heated it is used for ventilation. Applications of heated air are crop drying, and ventilating factories or apartment buildings.
Wind Power
Wind power is a method for capturing the wind’s energy
for practical uses. In the past, wind power was used for common chores liking pumping water for farms. In the Netherlands, large scale windmills were used to pump seawater out of low-lying areas, thereby reclaiming precious land from the sea. Today, wind power is used mostly to generate electricity.
The wind’s speed and consistency are very important. If the wind is turbulent then it is difficult to get
windmill rotors
moving fast enough to generate electricity. Many windmills start generating electricity when the wind reaches 4 m/s (about 14.4 km/hr or 8.6 mph). At this speed the windmill is not generating much power. As the speed increases, the output current increases by the square of the increase in speed.
Wind farms consist of wind turbines grouped in an area to generate
electricity for commercial purposes. Commercial wind farms are very popular in Europe where the cost of electricity is quite high. Ontario has some of the lowest electricity costs in the world so wind power is not very popular. A rough estimate shows that a commercial wind farm would require an average wind speed of approximately 7m/s (25.2 km/h or 15 mph) to be profitable.
Most residential locations in Ontario do not have consistently
strong winds. This means that wind power should be used in combination with other forms of power like solar energy. During the winter months, solar energy output wanes and winds get stronger. Residential wind generators offer power from as little as 90W up to 3000W or more. It is usually a good idea to have a site survey done beforehand to ensure that adequate winds are available.
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