Solar Thermal Technologies Heating Up
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Water heating dominates the short history of solar thermal technologies. The most recent statistics from the Energy Information Agency (EIA) highlight the market importance of low and medium temperature collectors used for either heating swimming pools or residential water heaters.
Solar water heating systems for pools, residential and industrial use, typically consist of a solar 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 because saving electricity also means avoiding the pollutants associated with electricity production.
The latest generation of solar thermal technology, concentrated solar power, used for the large scale production of electricity, offers the promise of even larger scale environmental benefits.
In its simplest form, a concentrated solar power plant consists of solar collectors (mirrors or parabolic dishes), that collect heat to transform water to steam, which in turn provides 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.
In 2007, the Nevada Solar One Power Plant, a 64 Mega Watt concentrated solar thermal plant came on line. The above video shows another concentrated solar thermal power plant planned for the Arizona desert. Currently it is being billed as the world's largest concentrated solar power plant, however, new projects on the drawing board could easily surpass its projected 280 Mega Watt generating capacity.
The use of the video does not constitute an endorsement of the company. Rather, its purpose is to show the basics of solar thermal technology, from the collector field to the steam turbines. Of special note in the video is the inclusion of a molten salt storage facility.
The limited availability of sunshine represents one big weakness of solar power. When the sun sets, new electricity generation comes to a halt. Research into storing solar power for use during no or low sun hours is ongoing, however, the use of molten salt as a storage device continues to gain acceptance.
Excessive water use to generate steam for turbines also raises concerns for plants planned in the water scarce desert southwest. Proponents of concentrated solar power consider it an engineering challenge rather than a stumbling block, with dry cooling and wet cooling technologies considered as viable options to reduce the amount of water evaporation during the electricity generation process.
As confidence in storage and water use technologies increases, solar thermal technologies will take their place in the mainstream electricity production process.
© 2009. Patricia A. Michaels.