Solar Thermal Power (image from afromusing on Flickr)
Solar thermal power, also known as concentrated solar power, is used to make solar energy more efficient – in other words, you get more electricity from the same amount of sunlight. Unlike photovoltaic solar panels which you might have seen on rooftops or powering traffic signals, solar thermal power is generated by huge satellite dishes that are fitted with special mirrors. The curvature of the mirrors focuses sunlight into a small, 7-inch area. As you might imagine, this focus area is blisteringly hot. Actually, unimaginably hot: the equivalent of 13,000 suns!
At the Solar Thermal Test Facility, owned by the U.S. Department of Energy, at Sandia National Laboratories in New Mexico, six solar thermal power dishes stand in the desert near Albuquerque. The official site notes:
The primary goal of the NSTTF is to provide experimental engineering data for the design, construction, and operation of unique components and systems in proposed solar thermal electrical plants planned for large-scale power generation. In addition the facility can provide: high heat flux and temperatures for materials testing or aerodynamic heating simulation; large fields of optics for astronomical observations or satellite calibrations; a solar furnace; a rotating platform for parabolic trough evaluation.
How does solar thermal power work? As the focus area in the center of each dish is superheated, the energy runs a “Stirling engine,” the operation of which is described in a San Francisco Gate article:
“The heat . . . creates mechanical energy from an external heat source, as opposed to the internal fuel combustion that powers most automobile engines. Hydrogen gas in a Stirling engine’s four 95 cc cylinders expands and contracts as it is heated and cooled, driving pistons to turn a small electric generator. The configuration of the dish and engine represent the fruit of more than a decade of steady improvements, developed in collaboration with Arizona-based Stirling Energy Systems.”
Concentrated Solar Power
In general, concentrated solar power is said to be 25% efficient, more than double the average 12% efficiency rate of ordinary photovoltaic solar panels. However, the dishes at the Solar Thermal Test Facility exhibited a 31.25% conversion efficiency – the highest ever recorded in a commercial solar device.
What’s equally exciting is that the energy comes from the heat of the sun, not the sunlight itself. Heat can be better stored so that solar energy continues after the sun goes down. The Solar Thermal Test Facility in New Mexico is just the beginning. More solar thermal power is coming in the future in Arizona, and additional concentrated solar power plants exist in the Mojave Desert in California.
The Department of Energy predicts that solar electricity will be less expensive than than grid prices by 2015. That’s just six years from now. We’re starting to see what the future of solar power looks like!
Tags: concentrated solar power, photovoltaic solar panels, sandia national laboratories, solar thermal power, solar thermal test facility
Wow, 13,000 suns. I think I’ll stay pretty clear of that 7 inch ray of light
That’s a really interesting technology. Solar power is making such cool advances these days. I’m really excited about it, as well as hydrogen energy. Those two energy sources are the way of the future I think.