Continuous Solar Production Via Torresol Solar Thermal Energy’s Plants

Gemasolar Plant


One of the problems I often heard discussed about solar and wind energy is there isn’t reliable cost effective storage options.  What happens when the sun isn’t shining that day or the wind isn’t blowing?   Torresol Energy’s Gemasolar in Spain is a  concentrated solar power plant that was built to solve this problem.  The Gemasolar plant can store solar thermal energy and then distribute it when needed.

When I think of this technology it reminds me of how passive solar works but on a larger and more expensive scale.  (The technology behind passive solar is the sun heats up a thermal structure like a stone floor.  The heat is then emitted back in the space at night.)

In a nutshell, the Gemasolar plant consists of 2650 large mirrors which are called heliostats.  The mirrors direct the sun rays to a receiver at the top of the a 450 foot  tower.  The tower contains  liquid salt consisting of 60% sodium nitrate and 40% potassium nitrate which is pumped up the tower to the receiver to soak up the sun rays.  The temperature of the salt liquid heat up to temperatures that can exceed 500 degrees Celsius or 932 degrees Fahrenheit.

The heat generated by the salt creates steam and produces electrical power.  Surplus heat is stored in the molten salts until needed.

According to the Company, the characteristics of the Gemasolar are as follows:

  • “Rated electrical power: 19.9 MW
  • Net electrical production expected: 110 GWh/year
  • Solar field: 2,650 heliostats on 185 hectares
  • Heat storage system: the molten salt storage tank permits independent electrical generation for up to 15 hours without any solar feed.
  • electrical production for 6,500 hours a year, 1.5 to 3 times more than other renewable energies.
  • The plant will thus supply clean, safe power to 25,000 homes and reduce atmospheric CO2 emissions by more than 30,000 tons a year.”
Watch the below Gemasolar video on how the system works.

CPS Twin Towers Valle 1 and Valle 2

Valle 1 and Valle 2

On the heels of Gemasolar, Torresol Energy’s twin tower Valle 1 and Valle 2 commenced operations in January 2012 in San José del Valle (Cádiz, Spain).  Unlike Gemasolar which use molten salt to store energy, Valle 1 and Valle 2 use a different technology.
“Valle 1 and Valle 2 use SENERtrough® cylindrical-parabolic collectors that concentrate solar radiation in a central collector pipe through which thermal oil is run and which is fitted with a high-precision optical sensor that monitors the sun from east to west. The hot oil is used to vaporize water which, by means of expansion in a steam turbine, drives an electrical generator that injects the energy into the grid.”
The project took two years to build and employed 4500 people.  The towers’ characteristics include:
  •  166 GWh of power per year
  • Equivalent power consumed by 40,000 households
  • Cut CO2 emissions by approximately 90,000 tons/yer
  • Continuous producing energy for 7.5 hours at full capacity without sunlight
  • Designed improvement reduce cost of collecting energy and construction of the plant.
 In the United States similar projects are planned.  I will be reporting on these projects.  In addition, I have reached out to Torrresol about the cost versus benefits of their systems.  Stay tuned.

Join the Conversation:

  • Do you think solar thermal projects like Gemasolar and Valle 1 and 2 hold the keys to making solar more efficient?
  • Does the benefit exceed the cost of these two projects or is the payback too long.
  • Is there another technology that you favor for thermal storage?

Photos courtesy of Torresol Energy

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