Gemasolar Solar Power Plant with Sunflower Shape Boosts Efficiency
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How Does the ‘Gemasolar’ Solar Power Plant Work?
Torresol Energy operates a number of concentrated solar power (CSP) plants worldwide. Their solar power plant Gemasolar is located in Spain and works by directing solar energy in the form of heat via mirrors at a central tower containing molten salts through the use of carefully arranged mirrors. The heat collected by the molten salts within the tower generates steam and is converted into electricity using steam turbines.
Solar heat from the mirrors converts the molten salts within the central tower into steam, which is then converted into electricity using steam turbines.
According to Gemasolar, the tower is capable of reaching temperatures above 500ºC.(R) The surplus of heat accumulated during hours of sunlight is stored in a tank of hot salts, which allows Gemasolar to produce electric power 24 hours a day throughout many months of the year. Its record for continual operation is 36 consecutive days. The energy generated by Gemasolar is sent to the Villanueva del Rey substation (Andalusia, Spain) via a high-voltage line, where it is fed into the electric grid to be distributed to consumers. The Gemasolar solar power plant currently supplies clean and safe energy to 27,500 household.
The initial arrangement of the mirrors used in Gemasolar proved to be problematic. It wasn’t until 2011, when they consulted the sacred geometrical shapes within the sunflower, that they found a solution to their inefficiencies.
Traditional vs New Sunflower Arrangement
The layout of the initial concentrated solar power plants involved the placement of mirrors radiating out in concentric circles with staggered rows so that each row was aligned. Researchers from MIT and RWTH Aachen University in Germany found that at various times during the day this arrangement was causing significant blocking of sunlight by the mirrors themselves. In other words mirrors were blocking sunlight from reaching adjacent mirrors. Another issue was that the mirror layout required a large amount of land.
Taking inspiration from the geometrical patterns in the sunflower, researchers have devices a more efficient design that would resolve the sunlight blockage and also allow concentrated solar power plants to be constructed on a smaller area of land. The answer, was to arrange the heliostats (mirrors) according to the shape of a fractal.
The Gemasolar central tower is surrounded by 2,650 heliostats arranged fractally that span approximately 185 hectares.
By modifying the heliostat layout using numerical optimization to create a narrower layout, the model calculated that the amount of land required for the mirrors could be reduced by up to 10 percent without affecting their efficiency in reflecting light. After noticing that the resulting pattern had some spiral elements similar to patterns found in nature, the researchers (naturally) looked that way for inspiration.
One such pattern is the Fermat spiral, which is found in the spiraling pattern of florets in daisies and, appropriately, sunflowers. The Fermat spiral has long been a subject of fascination for mathematicians who have found that each sunflower floret is turned at a “golden angle” of about 137 degrees respectively to its neighbor.
By rearranging the heliostats in a sunflower-like spiral pattern with each heliostat angled about 137 degrees relative to its neighbor, the researchers found they could reduce the footprint of the mirrors used in the layout by 20 percent while increasing the plant’s potential energy generation. By making the layout more compact, heliostat shading and blocking of neighboring mirrors is minimized.
MIT’s Alexander Mitsos says that by arranging heliostats in a spiral pattern, the costs of concentrated solar power plants could be reduced significantly because both the amount of land and the number of heliostats required to generate an equivalent amount of energy are reduced. “Concentrated solar thermal energy needs huge areas,” says Mitsos. “If we’re talking about going to 100 percent or even 10 percent renewables, we will need huge areas, so we better use them efficiently.”
Conclusion
It has been said that enough solar energy reaches the earth every 8 minutes to satisfy the world’s energy needs for an entire year. It’s clear that the sun provides us with the potential for energy abundance and that it’s just a matter of figuring out to harness it more effectively.
As far as concentrated solar power plants go, Torresol Energy’s innovative ‘sunflower’ fractal spiral arrangement moves humanity a little bit closer towards utilizing the sun as an energy source to its true potential.
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