How sunflowers are inspiring more efficient solar arrays

It's a solution that seems so obvious its amazing scientists haven't thought of it before. Recently, solar researchers have experimented with using the spiraling pattern found in the florets of sunflowers and daisies to more efficiently channel the sun in concentrated solar plants (CSP) by reducing the area needed for operation.

CSP plants use large arrays of mirrors (heliostats) to focus the sun's rays into a small area. The concentrated light is converted into heat, which then generates electricity. A popular alternative to fossil fuels, plants have sprung up in many countries - their only drawback being they require large areas of land to make them valuable.

This has been in part to their layout. Generally the CSPs have used a staggered design that spreads out from one side of the central tower. Each mirror would be positioned in between the spaces of the mirrors in the row ahead of it under the assumption they would maximize the sun's rays that way.

It turns out that belief was way off. Researchers from MIT and RWTH Aachen University in Germany ran a computer model at Spain's 11-megawatt PS10 plant and found significant shading and blocking during the day.

That led to a look at the sunflower, that naturally channels the sun every day with its spiraling florets. The spiraling pattern known as "the Fermat spiral" has long held fascination for scientists and mathematicians who have studied the perfect or "golden angle" of the florets — a perfect 137 degrees in relation to its neighbor — becoming a tight spiral.

When they rearranged PS10's mirrors just like the sunflower in a perfect 137 degrees in relation to each other it reduced the footprint needed to operate by 20 percent and increased potential energy production. The precise angles and compact spiral naturally reduced the shading as well.

Utilizing the Fermat spiral in CSPs ticks all the boxes — it either reduces the amount of land needed to generate results, or it allows for more mirrors to be utilized in the same areas as before. Either way, more efficient.

The MIT and RWTH Aachen University team have published their findings in the journal Solar Energy, and have filed for patent protection on the concept.

I have to wonder what Mother Nature would say about that!

Via Gizmag

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