A sunnier approach to solar

The solar industry is continuing to find new ways to deliver the clean energy resource, as well as increasing capacity.

Researchers from the Massachusetts Institute of Technology (MIT) have used inspiration from a common flower to help change the design of a concentrated solar power (CSP) plant in Spain.

Located in the desert region of Andalucia, Spain, the city of Seville is home to the PS10 solar plant - a 100 metre high pillar surrounded by giant mirrors.

The 11 megawatt facility collects sunlight reflected by a field of more than 600 mirrors - the light is reportedly so intense that dust and water vapour in the air are visible.

Ample land is a requirement of CSP plant - while the PS10 generates enough power for 6,000 homes, each of the 624 mirrors is half the size of a tennis court.

However, MIT researchers - assisted by the German research university RWTH Aachen - have developed a design that could reduce the land mass needed for such a project, publishing their results in the Solar Energy journal.

"Concentrated solar thermal energy needs huge areas," head of the MIT research group Alexander Mitsos said yesterday (January 11).

"If we're talking about going to 100 per cent or even 10 per cent renewables, we will need huge areas, so we better use them efficiently."

According to the academics, the PS10 mirrors - also known as heliostats - could be rearranged in a pattern "similar to the spirals on the face of a sunflower" in order to reduce the site by 20 per cent while increasing its potential energy generation at the same time.

Test results generated by a MIT lab computerised model discovered that by bringing the fanned-out layout currently used closer together to resemble more of a spiral pattern could reduce the amount of land the mirrors took up by 10 per cent without affecting the mirrors'
efficiency in reflecting light.  

Researchers recognised the circular pattern as a regular occurrence in nature, including the Fermat spiral of the sunflower.

"Each sunflower floret is turned at a 'golden angle' - about 137 degrees - with respect to its neighbouring floret," MIT said in a statement (January 11).

Applying this natural equation, researchers devised a spiral field with its heliostats rearranged to resemble a sunflower, which resulted in a more compact layout that helped to minimise shading.

Researchers have recently filed for patent protection based on their findings and Mr Mitsos told news channel MSNBC that he hopes that developers in the CSP industry will adopt his design.

Posted by Mike Peacock - Solar correspondent

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