alternatemethod

Alternate Way of Producing Electricity

There are two main types of solar electricity generation, photovoltaic cells and solar thermal plants. Photovoltaic (PV) cells convert the suns electromagnetic radiation directly into electricity. Where as Solar thermal plants rely on the sun's energy to heat up a fluid, such as water, to produce a gas, such as steam, to drive a turbine and generate electricity.

A photovoltaic cell is made of two thin sheets of silicon that are separated from each other. When sunlight passes through the sheets the energy from the sun is absorbed by the silicon causing 0.6 volts of electricity to be produced. When several cells are connected together (in series) the voltage produced increases.

Solar thermal systems use large mirrors or reflectors to focus the sun's energy onto a receiver. There are three main designs: Parabolic Trough, Power Tower, and Dish Systems. The most common is a parabolic trough mirror oriented north-south, which tracks the sun's path through the day. The absorber or receiver is located at the focal point and converts the solar radiation to heat (about 400^oC). The receiver usually contains a liquid (such as highly concentrated salt water or synthetic oil) that absorbs the solar energy and is heated and turned into a gas. The gas then drives the turbine.

In Australia there are a number of commercial solar generation plants that contain many photovoltaic cells, connected together to produce electricity. The electricity produced is converted to AC from DC and distributed to a major substation. From there it follows the same path as electricity produced by fossil fuels.

Advantages:

�� Solar thermal plants and photovoltaic cells do not produce greenhouse gases. Photovoltaic cell technology contains few moving parts and requires little maintenance.

�� Photovoltaic cells can be placed on rooftops for domestic and certain commercial/industrial applications, which leaves land (such as backyards) free to be used for other purposes.

�� Photovoltaic cells are ideal for electrical generation in remote locations.

�� Australia has a lot of sun!

Disadvantages:

�� The generation of electricity from photovoltaic cells and solar thermal plants is costly compared to the generation of electricity from fossil fuel. These costs are expected to fall as sales and production increase.

�� The generation of electricity from solar energy is unreliable. The sun's light may reach the panels intermittently, and other factors, such as the sun's position relative to the solar panel and atmospheric conditions (such as clouds), may have an effect on solar energy generation.

�� Some solar-generated electricity has to be stored to have a continuous supply, for example at night. Storing the electricity in batteries, or using it to pump water to a storage dam from which it can later be released through a hydro-electricity generation facility can do this.

�� Electricity generation from photovoltaic and solar thermal systems require vast amounts of land for large facilities.

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Last Modified 6/14/05 8:32 PM