As for the stored molten salt reservoir the efficiency would be low. Efficiency in a conventional steam plant and this molten salt plant are is governed by the temp difference between the high and low temps. In a conventional superheated steam plant the steam can be hotter than 1100 deg F and is cooled in the condenser to less than 100 deg F. That's about a 1000 deg F temp difference. This molten salt plant operates between 500 deg F and somewhere around 300 deg F. You cannot allow the salt to solidify because you couldn't pump it back out to the solar collectors. So a 200 deg F temp difference, on fifth what a conventional steam plant gets.
Where engineers worry about a couple of degrees of temp loss affecting plant efficiency 800 deg is just silly.
They are using a mix of Sodium and Potassium Nitrates apparently spiked with some Ca(NO3)2 to reduce the melting temp. Those nitrates are strong oxidizers (think gunpowder which is 75% nitrates) and the effect of 500 degree molten nitrate hitting a blob of spilled grease could be very exciting.
I suspect those hot salts would be corrosive and heck on the machinery lifespan too unless you construct the plant out of exotic and very expensive alloys like Carpenter 20 or Inconel.
Just because they built a prototype does not mean it is an economically feasible idea. They have built several prototype solar highway project, which is a completely stupid idea. And these prototypes do produce some tiny amount of power but are completely economically a failure. And that shows that these people who are religiously bonded to this renewable energy stupidity are absolutely immune to logic. The engineers who signed off on those projects should lose their licenses.
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