Researchers develop new method to remove dust on solar panels

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Taking a cue from the self-cleaning properties of the lotus leaf, researchers at Ben-Gurion University of the Negev have shed new light on microscopic forces and mechanisms that can be optimized to remove dust from solar panels to maintain efficiency and light absorption. The new technique removed 98 percent of dust particles.

In a new study published in Langmuir, the researchers confirmed that modifying the surface properties of solar panels may greatly reduce the amount of dust remaining on the surface, and significantly increase the potential of solar energy harvesting applications in the desert.

Dust adhesion on solar panels is a major challenge to energy harvesting through photovoltaic cells and solar thermal collectors. New solutions are necessary to maintain maximum collection efficiency in high dust density areas such as the Negev desert in Israel.

“In nature, we observe that the lotus leaf remains dust and pathogen free due to its nanotextured surface, and a thin wax, hydrophobic coating that repels water,” says Tabea Heckenthaler, a master’s student from Düsseldorf Germany at the BGU Zuckerberg Institute for Water Research, Jacob Blaustein Institutes for Desert Research. “In the desert, dust accumulates on the surface of solar cells and it’s labor-intensive to clean them constantly, so we’re trying to mimic this behavior on a solar cell.”

The researchers explored the effect of modifying a silicon substrate (Si), a semiconductor used in photovoltaic cells, to mimic the self-cleaning properties of the lotus leaf, as water rolls down the leaves and removes contamination.

It is known that superhydrophobicity reduces the friction between water droplets and the surface, thus allowing water drops to slide clean particles from surfaces. However, the forces that attach and detach particles from surfaces during the self-cleaning mechanism and the effect of nanotextures on these forces are not fully understood.

To shed light on these forces and the effect of nanotexture on them, the researchers prepared four silicon-based samples relevant to solar panels: (1) smooth hydrophillic (2) nanotextured hydrophilic surfaces and (3) smooth hydrophobic (4) nanotextured hydrophobic surfaces. This was achieved by wet-chemically etching the surface to create nanowires on the surface, and additionally applying a hydrophobic coating.

Particle removal increased from 41 percent on hydrophilic smooth Si wafers to 98 percent on superhydrophobic Si-based nanotextured surfaces. The researchers confirmed these results by measuring the adhesion of a micron-sized particle to the flat and nanotextured substrate using an atomic force microscope. They found that the adhesion in water is reduced by a factor of 30.

“We determined that the reason for the increased particle removal is not low friction between the droplets and the superhydrophobic surfaces,” Heckenthaler says. “Rather, it is the increase in the forces that can detach particles from the surfaces. The experimental methods we used and the criterion for particle removal we derived can be implemented to engineer self-cleaning surfaces exhibiting different chemistries and/or textures.”

 

Source: Phys.org

Israeli ‘rubber band’ solution could reduce plastic bottle waste by 80%

A French-Israeli entrepreneur believes that recycling challenges posed by large quantities of plastic bottles could be significantly ameliorated with a rubber band.

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It is often said that necessity is the mother of invention, but what about simplicity?

According to the Ellen MacArthur Foundation, there could be more plastic than fish (by weight) in the ocean by 2050, if current plastic disposal trends continue. In fact, only 14% of the world’s masses of plastic packaging materials is collected for recycling.

One French-Israeli serial entrepreneur, however, believes that recycling challenges posed by large quantities of plastic bottles could be significantly ameliorated with a solution based on the addition of a rubber band.

On Monday, Morris Amsellem, the CEO of waste solution company Ecoams Planet, unveiled Bakbuk: a simple solution to crush plastic bottles and make recycling easier for consumers and beverage manufacturers alike.

Key to the uncomplicated solution is a biodegradable rubber band strapped around a particular part of the bottle, which assists consumers to easily fold up their empty bottle and reduce its volume by 80%.

Reducing the volume, Amsellem says, will enable eager recyclers to save space and reduce the frequency required to deposit waste in the recycling bin or travel to the refuse center.

The rubber band solution, which already boasts patents in 14 countries, can be implemented on any type of original PET plastic bottles, including those used by the world’s leading beverage makers. Patent applications have been filed in 58 countries worldwide to date, led by Israeli patent and trademark firm Ehrlich & Fenster.

“Bakbuk is bringing a revolution in all phases of recycling: for the consumer it is simple and efficient to use, reduces the frequency of throwing [bottles] into the recycling bin by a factor of five, and provides a tremendous ecological response to catastrophic plastic pollution worldwide,” said Amsellem.

“In addition, for the recycling company, it reduces the number of journeys to recycling sites, reduces transportation and compression costs, and generally increases efficiency and productivity. For the beverage companies, it provides solutions for sustainable development, a ‘circular economy’ solution and a solution that is relevant to customers.”

The company is currently in talks to include its solution in bottles sold by major beverage manufacturers, and thereby bring the innovation directly to consumers’ households. Amsellem’s efforts are advanced by a positive entrepreneurial track record, including the $21 million sale of a simple plant watering system in 2006 to a public French company.

According to a US survey conducted for Ecoams Planet by Ipsos, 91% of consumers said that a solution reducing the volume of large drinking bottles by 75-80% was an important innovation. A total of 69% said they would be willing to spend at least one cent extra on a shrinkable plastic drinking bottle, including 12% who said they would be willing to spend more than five cents extra on such a product.

Recommended PET bottle recycling machinery:

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ACERETECH ACS-H TM series compacting and pelletizing system combines function of crushing, compacting, plasticization and pelletizing to One step. Applied in the plastics recyclng and pelletizing process. ACS-H TM system is a reliable and efficiency solution for plastics film, raffias, filaments, bags, woven bags and foaming materials re-pelletizing.

 

Source: The Jerusalem Post