When comparing LECs for alternative systems, it is very important to define the boundaries of the 'system' and the costs that are included in it. For example, should transmissions lines and distribution systems be included in the cost? Typically only the costs of connecting the generating source into the transmission system is included as a cost of the generator.
A polygon is "traditionally a plane figure that is bounded by a closed path or circuit, composed of a finite sequence of straight line segments". This article will show you how to make a polygon building using SketchUp.
Google Sketchup is a great product. If you want to know how to use it,here is a step to step manual about using this software. Begin by downloading a free copy of the software. It is available from http://sketchup.google.com/download.html.
Energy sources are used as fuels. Fuel is burned in machinery to create motion (such as in a car) or heat (such as in a home heating system). When fuels are used for producing electricity, heat or motion causes a generator to rotate, creating electricity for everyday use in homes and businesses.
Our energy choices have direct implications for our health, our environment, and our climate-and right now we are dangerously dependent on coal and other fossil fuels for most of our electricity needs. Power generation is a leading cause of air pollution and the single largest source of U.S. global warming emissions.