by Timothy Blankenhorn

Created on: December 08, 2008   Last Updated: January 16, 2009

As Boy Scouts, we learned to light fires with a magnifying glass. We'd use the glass to focus sunlight into a bright spot on a pile of dry leaves. It would begin to smoke, then erupt in flames. We didn't think of it as solar power, but that's what it was.

This commonsense method for using sunlight to create power, called officially Concentrating Solar Power (CSP), is a major focus of worldwide research and pioneering utility-scale efforts to create electrical power without using fossil fuels. CSP is a promising green technology. Already in use by power companies, it will only be put to more and more use, as the approach is simple, dependable, safe, and increasingly inexpensive.

We are used to associating solar power only with photovoltaic cells, the dark tiles we see on roofs or even on small electrical devices. We know that they convert sunlight directly into electricity in ways that are too technical for most of us to grasp with confidence.

But we can understand that, if we use our magnifying glass to concentrate sunlight on such solar cells, we can multiply their effectiveness. If everyday sunlight is good for the photovoltaic cells, then surely denser sunlight is even better! Some researchers have used lenses to magnify sunlight onto cells 2300 times normal sunlight!

A similar use of concentrating solar energy are Dish/Engine systems. These are individual parabolic discs, that look like large round radar dishes, that convert concentrated sun light directly into small heat-driven engines, and then into electricity. Sunlight goes in, in other words, and electricity flows out, through a wire. They can be used individually or in clusters.

Other, more advanced applications of CSP are just as easy to understand. These are large-scale ways of using lens-like mirrors to create heat, and to send that heat to a central turbine, where it generates electrical energy. We have become quite good at converting heat to electricity because all along we have used coal, oil, and natural gas to create power by creating heat. CSP, though, takes the energy directly from the sun to make the heat - without creating carbon dioxide or other pollutants.

A Power Tower system consists of a tower in the middle of a ring of elliptical mirrors. These mirrors are run by computers that aim them so that they are individually focusing a beam of concentrated sunlight on the tower, moving steadily and slowly all day long as the sun crosses the sky. The heat created in the tower is very intense and

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