Salts Used for 24-Hour Solar Energy Generation

The salt of the earth now brings light to the world in more ways than one.

A thermal power plant powered by the sun’s heat can now generate heat even during cloudy days and nights. Dubbed Archimede (after the scientist who was said to have burned enemy ships with sunlight concentrated using mirrors), the power plant is located in Syracuse, Sicily, and can generate five megawatts of electricity day or night.

This was made possible by using molten salt as storage; massive arrays of parabolic mirrors keep the energy trapped. They concentrate reflected light onto high heat-resistant tubes containing the salt. The heat from the molten salt—kept at 550 degress Celsius—produces steam that drives turbines.

Molten salt does not have the inherent dangers of the oils used in other solar-concentrating power plants. If the pipe system springs a leak we’d only get piles of fertilizer, not a massive cleanup problem. The downside is that the freezing point for these salts is a rather warm 220 degrees Celsius; hence the need to kickstart things by burning natural gas.

Another drawback with the setup is the massive infrastructure cost – 30,000 sq. meters of special parabolic mirrors and 5,400 meters of specialized piping worth roughly USD80 million for a paltry five megawatts of electricity. However, more are following the footsteps of Italian energy giant Enel. Research to apply economies of scale is underway.

Via Scientific American

Photo courtesy of Archimede Solar Energy