14 DAY TRIAL // Archimede is the name of the first molten salt concentrating solar power plant in the world. It was built by the Italian utility Enel and ENEA, the Italian National Agency for New Technologies, Energy and Sustainable Economic Development. This 5 MW plant is located in Priolo Gargallo (Sicily), in the largest petrochemical district in Europe.
The difference between Archimede and older CSP plants is that these last completely rely on direct sunlight, thus can only function during the day. This new plant can operate much longer, as the molten salts stores a lot more energy, and it is also the first plant that uses molten salts not only to store heat from the sun, but also to collect it.
Molten salts work at higher temperatures than the synthetic oils from traditional CSP plants, meaning it can go up to 550°C and not be limited at 390°C. Molten salts CSP plants can also function for much longer, being able to operate 24 hours a day for several days, without sunlight. This way the power output and the efficiency of the plant are higher, CleanTechnica.com says.
Another advantage of Archimede is that it does not require oil-to-salts heat exchangers, thus eliminating concerns about the ecological part of oil use. “Molten salts are cheap, non-toxic common fertilizers and do not catch fire, as opposed to synthetic oils currently used in CSP plants around the World,” writes Carlo Ombello of Guardian News. “The higher temperatures reached by the molten salts enable the use of Steam turbines at the standard pressure/temperature parameters as used in most common gas-cycle fossil power plants. This means that conventional power plants can be integrated – or, in perspective, replaced – with this technology without expensive retrofits to the existing assets.”
The only inconvenient with this type of CSP plants is that salt tends to solidify at 220°C. Using the specific technology that prevents the solidification is what raised the final price considerably, the building of Archimede ending up at an incredible €60 million ($77.5 million). Still, Ombello says that “there is overwhelming scope for a massive roll-out of this new technology at utility scale in sunny regions like Northern Africa, the Middle East, Australia, the US.”