Solar Thermal Technologies

Solar thermal technologies work on some very simple principles, with albedo one of the easiest to understand.

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Albedo is a scientific term describing the amount of light, and consequently heat, a material reflects or absorbs. Generally speaking, lighter colored materials have a higher albedo, meaning they reflect a higher percentage of light and heat away from them. Wearing white or light colored clothes in the summer is not only fashionable, it's also practical.

Darker colored materials, on the other hand, absorb more light and consequently heat. Solar thermal technologies pick up on the idea of albedo and use black colored plates as their core heat collecting device.

Solar thermal technologies also fall into either a passive or active category and are usually distinguished by their having an additional level of activity connected to the heating process. The simplest example of passive solar heating is opening the draperies during the winter to let the sun in and heat the room.

Passive solar thermal technologies move up the complexity ladder in instances that require a concentrated collection of sun heat, such as for heating water. Commonly a solar water heating system, for pools, residential and industrial use, consists of the collector, which gathers the sun's heat and transfers it to water passing thought the plumbing system on its way to a storage container. Solar water heating systems save money by reducing the electricity costs associated with traditional water heating. They are also environmentally friendly. Saving electricity in most cases means avoiding the types of emissions associated with electricity production.

Active solar thermal technologies run the gamut of simple to complex machinery. Solar water heating systems unable to operate on basic water pressure and gravity principles, require the use of electric or other pumps to move the cold water through the collector. Larger scale solar thermal projects for electricity generation promise to be the next wave of sun heated water practices and operate on principle similar to their small scale counterparts. Even the non-scientist understands that water heated to very high temperatures turns to steam.

The latest generation of solar heating technology, concentrated solar power, consists of collectors (mirrors or parabolic dishes) that can either move and track or gather an adequate amount of sun to transform water to steam. The steam serves as a force to move electricity generating turbines. The environmental benefits are obvious. Emissions from steam generated electricity share little in common with their cousins, emissions from fossil fueled generated electricity plants, the primary causes of air pollution such as smog, acid rain and climate change.

© 2001. Patricia A. Michaels.