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Sunflowers inspire more efficient Concentrated Solar Power plant layout

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January 11, 2012

The Fermat spiral found in the spiraling pattern of florets in sunflowers has inspired a m...

The Fermat spiral found in the spiraling pattern of florets in sunflowers has inspired a more efficient CSP plant layout

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Concentrated Solar Power (CSP) plants, such as the Gemsolar and PS10 plants in Spain, use arrays of mirrors (or heliostats) to focus a large area of the Sun's rays onto a small area, where the concentrated light is converted to heat that is used to generate electricity. While CSP has gained popularity in recent years with numerous plants being built around the world, they require a large area to generate the amounts of electricity needed to make them economically viable. Taking inspiration from the sunflower, researchers have devised a more efficient design that would allow such plants to be constructed on a much smaller area.

Most current CSP plants see mirrors fanning out from one side or radiating out from a central tower in concentric circles with the rows staggered so that every second row is aligned. After running the dimensions of Spain's 11-megawatt PS10 plant - which uses a fanned-out layout - through a computational model, researchers from MIT and RWTH Aachen University in Germany found that there was significant blocking and shading of the heliostats each day.

The PS10 CSP plant (bottom) in Spain (Photo: Koza1983 via Wikipedia)

Spain's PS10 CSP plant (bottom) is Europe's first Concentrating Solar Power plant

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 naturally-occurring pattern is the Fermat spiral, which is found in the spiraling pattern of florets in daisies and - fittingly - sunflowers. The Fermat spiral has long fascinated mathematicians who have found that each sunflower floret is turned at a "golden angle" of about 137 degrees with respect to its neighbor.

By rearranging the mirrors in a sunflower-like spiral pattern with each mirror angled about 137 degrees relative to its neighbor, the researchers found they could reduce the footprint of the mirrors used in the PS10 layout by 20 percent while increasing the plant's potential energy generation. This is because the more compact sunflower-inspired layout minimizes the heliostat shading and blocking of neighboring mirrors.

MIT's Alexander Mitsos says laying heliostats out in such a spiral pattern could significantly cut the costs of CSP plants by reducing the amount of land and the number of heliostats required to generate an equivalent amount of energy.

"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."

The MIT and RWTH Aachen University team have published the results of their research in the journal Solar Energy, and have recently filed for patent protection.

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick
4 Comments

This perhaps is the best lesson one can learn from Nature's architecture. Sunflower is composite flower with 'Ray florets(small flowers are called so)" and 'Disc florets'. The orientation of each of these florets is so perfect that each one of them receives the desired intensity. In fact, the sun flower derives its name because of angling towards sun all the time throughout day by bending towards sun.

I do understand the above model cannot incorporate this character of Sun flower. I appreciate the designers emulating sunflower architecture to provide the best option in a limited area. This should provide ample opportunity to those who were a little skeptical on the area requirement for solar application.

A combination of recent developments on solar is indeed pretty encouraging for meeting energy needs of future.

Akshay
12th January, 2012 @ 02:53 am PST

My favourite video on the subject

Paul Hutchinson
12th January, 2012 @ 05:21 am PST

That is THE funnest video I've ever seen. thanks Paul !!!!!!!!!!!!!

Back to mirrors though... maybe it's not so wise to optimize this stuff? Creating deserts of barren sun-deprived land under optimal mirrors seems rather plant-hostile to me. My grass grows best *under* the kids trampoline - suggesting that there's a "sweet spot" we might aim for that makes life better for plants, while also harvesting that excess for us to use. win win?

christopher
13th January, 2012 @ 08:53 am PST

Hasn't anyone developed such a solar powered facility which converts seawater to H2 and O2 (piped to distributed fuel cell/combustion electric substations) rather than to electricity which need be conveyed over high-tension cables and pylons? It seems to me using the electric harvested to extract, convey and store these primary gases is more energy AND cost efficient overall due to 'line losses' and lack of adequate electric storage technologies. Whereas there have existed many gas storage facilities in/around population centers - I don't know of any electric battery/capacitor storage technologies with comparable capacities.

Larry
21st January, 2012 @ 08:31 pm PST
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