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20MW Gemasolar Plant: Elegant, But Pricey

Gemasolar heliostats and towerTorresol Energy has announced the commissioning of its Gemasolar CSP electrical plant.  It went on-line 5/24/2011, with a maximum output of 19.9 MW, and 15 hours of thermal energy storage, which allows it generate power 24 hours per day many months per year.  The plant (formerly called Solar Tres when the business partners were different), is located near Seville, Spain (the Andalucía region). 

The annual electrical output of 110 MWh/year equates to a capacity factor of 63.1%.  This is the highest value of any production solar plant in the world. This is not quite baseload, but it would need half the fossil fuel backup of PV technology.  It would also have one third of the transmission cost of PV (making the best solar choice for projects like ).  The secret of the high capacity factor is the sunny location (expected 270 productive days/year), and a solar field that is so over-sized that significant summer collection is discard in order to get more operating hours during the rest of the year.

Gemasolar is the first commercial central tower plant equipped with a molten nitrate salt thermal energy storage system, first demonstrated by the US DOE at the Solar Two plant in Barstow California in 1998 (ignoring the very small French Themis experiment).  The Spanish engineering company SENER (part owner of Torresol) has apparently developed their own molten salt technology since Boeing/Rocketdyne (which built the Solar Two receiver) left the project.

The UK’s Daily Mail has reported the cost of this small first-of-a-kind plant to be £260million, or about US $419M.  This equates to a quite pricey $33 per average Watt delivered, several times higher than the cost of wind, geothermal, or nuclear.  However, it’s only somewhat higher than other solar options: $4/Wpeak PV would be $20/Wavg. 

Torresol has announced that the combined cost of Gemasolar and two larger 50MW plants using more mature trough technology (7.5 hour storage, 38.8% CF) was 940 million Euros, so their average cost is lower at $25.7/Wavg.

In related work, Solar Reserve ( ) is working on a central tower plants in Blythe California and Crescent Dunes Nevada, which would utilize molten salt storage, and Brightsource ( ) is working on a central tower plant in Ivanpah California that would skip the storage and use simpler direct steam generation.

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