You are probably familiar with concentrating solar power (CSP), but a new type of CSP plant, a molten salt CSP plant, has just gotten rolling and you may not yet know why that is important.
The “Archimede” (as this new power plant is called) was built by the Italian utility Enel and ENEA, the Italian National Agency for New Technologies, Energy and Sustainable Economic Development. It is a 5 MW plant located in Priolo Gargallo (Sicily), inside Europe’s largest petrochemical district.
Older CSP plants, completely reliant on direct sunlight, can only operate in daytime. Newer CSP plants, however, use molten salts storage so that they can operate for longer. But Archimede is the first CSP plant that is using molten salts to collect heat from the sun, not only store it.
This is good because molten salts can work at higher temperatures than the synthetic oils used in traditional CSP plants (up to 550°C rather than 390°C). So, efficiency and power output of the plant is higher.
Such plants can also operate for much longer. They can go 24 hours a day for several days without sunshine.
Additionally, no oil-to-salts heat exchangers are needed and safety and environmental concerns related to the use of oils are also eliminated. As Carlo Ombello of Guardian News writes, “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.”
Additionally, here is a big one: “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 problem with molten salt CSP plants is that salts tend to solidify at around 220°C, and in order to address that, some expensive technological developments were needed that currently drive the price of the plants up a bit. Archimede was built for a whopping €60 million ($77.5 million)! Quite a lot for a 5 MW power plant. But, Ombello writes, “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.” We will see.
Photo Credit: Enel via Guardian News