The word “solar” has become synonymous with solar panels and photo voltaic cells. However, there is also another way of transforming Sun’s energy into electricity, and the technique is called solar thermal power generation.
How are Solar Thermal Plants Different from Solar Panels?
As of now there are two ways of converting solar energy into electricity. Conversion of sunlight directly into electricity using solar panels is the most popular technique. However, this method is not suited for large scale production of electricity, since a very small percentage of Sun’s energy is actually converted into electricity by photovoltaic cells. The other method, involves using the Sun’s thermal energy to heat boilers and drive steam turbines – the way it is done in coal fired power plants.
Luz Solar Thermal Power Plants
The Israeli-American company Luz is the first commercial producer of solar thermal electricity. The company started operations sometimes around 1984 and in a span of six years It built 9 power plants in the Mojave Desert in California.
In Luz power plants, large curved mirrors focus Sun’s heat on a small area. The focused energy of the Sun falls on a glass surface and heats up double layered tubes located under the glass. The tubes contain oil which gets heated by the Sun’s energy, and this heated oil is pumped around boilers to produce steam and run steam turbines.
In the absence of sunlight, natural gas burners heat the boiler and keep the plant running. But a major bulk of electricity is produced using Sun’s heat. Luz power plants provide electricity to about 350,000 houses in California, and in more than two decades of operation the company has generated about 11,000 watt hours of clean electricity.
The concept of running conventional steam turbine power plants by using Sun’s energy is probably the best way of combating global warming. Apart from being clean, the method is cheap since the cost of fossil fuels is increasing by the day.
Many companies have attempted to refine the process of solar thermal power generation and thus make the process more efficient. One of the problems associated with solar thermal power generation is the setup cost. Setting up a power plant requires great deal of money since parabolic reflectors are expensive. A company named Ausra, which is owned by a physicist David Mills has built a solar thermal power plant using Fresnel reflectors. Fresnel reflectors are created using strips of glass and they can be manufactured at the site. Additionally, the Ausra power plant uses water instead of oil to heat boilers, thus making energy production all the more cheap.