The Guardian subtitle to my post was misleading, as I promptly wrote to them when they posted. Nonetheless, if you read the full article (and comments) you will not find wrong information, the “world first” claims are correct.

The Archimede plant is indeed the first in the world to use molten salts to transfer heat from the pipes in the parabolic troughs, and then also to store the high level heat. The very point of the whole article is highlighting the differences such a solution makes in the “quality” of the heat collected in the troughs, and in the simplified design it conveys compared to current technology.

Also, the steam turbine used is the one existing in the adjacent gas plant, to which Archimede is connected. Archimede is the first CSP plant in the world to match standard gas-cycle steam turbines parameters.

For any further queries you’re more than welcome to check my blog and add comments. Also, links are provided to retrieve further information from ENEA, ENEL, or pipe developers Archimede Solar Energy.

Hope this helps.

Regards

Carlo Ombello

No, read the article again! The Archimedes power plant is first because it uses molten salt as heat transfer fluid in the tubes of the mirror array. All previous parabolic trough plants have used a sort of oil in a closed system as heat transfer from mirror array to boilers/storage system.

The Solar Two plant was a (solar thermal) tower design, not a parabolic trough design and hence do not use heat transfer fluid. So the reference is not relevant to the article.

The central tower design has the advantage of having the mirrors directly reflecting on to the boiler/storage system. However the disadvantage is that the central power tower design cannot scale very far, as additional mirrors would have to be placed to far away from the central boiler to be effective.

Arrays of parabolic trough does not have the same need to be that close to boiler/storage system and hence can scale up to much larger plants.

The largest tower design is the PS20 (20MW) at Seville in Spain, whereas the typical parabolic trough plants are 50MW and could without much problems be made several 100MW.

I salute Archimedes in Italy for trying a new heat exchange method. If this method do not run into problems with corrosion, solid salt blocked in pipes or other unforeseen complications, this may become the standard CSP design in 5-10 years time.

Doei RIF

“In 1995 Solar One was converted into Solar Two, by adding a second ring of 108 larger 95 m² (1,000 ft²) heliostats around the existing Solar One, totaling 1926 heliostats with a total area of 82,750 m² (891,000 ft²). This gave Solar Two the ability to produce 10 megawatts. Solar Two used molten salt, a combination of 60% sodium nitrate and 40% potassium nitrate, as an energy storage medium instead of oil or water as with Solar One.”