Monthly Archives: July 2017

Morphological changes of dust particles

Real-time evidence of morphological changes of dust particles due to internal mixing with pollution

Frequent occurrence of both anthropogenic pollution and natural dust in East Asia has great impact on regional air quality, human health and climate. Until now, their interaction and consequent effect on dust morphology remain statistically unclear, because even though the traditional filter-based bulk sampling method can provide accurate chemical compounds, it cannot distinguish the mixing state of chemicals with dust particles.

“Single-particle inspection using electro-microscopy can identify coated/contaminated dust particles,” says Dr. PAN Xiaole from Institute of Atmospheric Physics, “but real-time measurement on the morphological variation of dust particles was difficult due to labor-intensive manual operations.” In a recently published paper in Scientific Reports, PAN and his collaborators from China and Japan investigated polarization of the oscillation direction of the back-scattering signal of single dust particles online using a newly developed bench-top optical particle counter.

A real-time decrease in Asian dust depolarization was observed in North China for the first time. PAN reckons that it can only be caused by the decrease in the particle aspect ratio, which was reflected by the coating of an air pollutant, such as the deliquescent dust-nitrate Ca(NO3)2. “This phenomenon was obvious when the dust particles were stagnant in a polluted region with a high relative humidity condition,” says PAN. The statistics highlight the significant importance of internally mixed “quasi-spherical” Asian dust particles, which were more hygroscopic and likely to act as cloud condensation nuclei (CCN).

Because the NOx emission in East Asia has been rapidly increasing over the last decade, their findings imply that nitrate has become increasingly important on the morphological change of Asian dust and its subsequent spatial allocation.

“Nitrate plays a leading role in regional climate change,” PAN concludes. He adds, “Many processes associated with the direct/indirect effects of dust-nitrate are still insufficiently understood, and this requires more attention from the public and poses another challenge for the observation and modeling communities.”

Their findings have been published and online in Scientific Reports.

Morphological changes of dust particles

Read more at: https://phys.org/news/2017-05-real-time-evidence-morphological-particles-due.html#jCp

I trust you found this article on Morphological changes of dust particles interesting!  Enjoy your day!

Dust Monitoring Equipment – providing equipment, services and training in dust fallout management to the mining industry.

An energy-efficient cleaning robot

State-of-the-art solar cells are efficient – but are even more so when they are kept clean. A cleaning robot developed by Norwegian researchers enables solar panels to deliver at full capacity.
An energy-efficient cleaning robot

At a solar energy farm just outside Budapest in Hungary, a cleaning robot is industriously getting on with today’s task. Hundreds of square metres of solar panels are waiting to be cleaned – as quickly and effectively as possible. And without the use of chemicals or any unwanted discharges to the natural environment. The robot is the result of a joint project between Norwegian researchers and the Hungarian company ProDSP Technology.

“It’s a well known fact that solar panels work more efficiently when they’re clean,” says SINTEF researcher and Project Manager Martin Bellmann who, in his day-to-day work, develops what is known as sustainable energy technology. “But what’s new here is that we’ve developed a robot to do the job. This means that the solar are cleaned both quickly and efficiently with as little as possible wear and tear or environmental impact,” he says.

There’s dirt and there’s dirt

Cleaning solar cells using a robot may sound like a straightforward job – but there’s dirt and there’s dirt. And when a solar farm covering several square kilometres is being cleaned, no chemicals can be used, and there must be no damage to the natural environment. So how do we get to grips with a challenge like this?

Solar cell researcher Birgit Ryningen is examining a set of glass plates in SINTEF’s Daylight Laboratory. They are all contaminated to order, but in different degrees.

The reason is that the dirt in question has been precisely applied. These plates will now be studied in detail by researchers in order to provide answers about how much the contamination occludes sunlight. This is the final phase of the project.

There really are all kinds of dirt. “The degree to which dust particles and contamination affects solar cells is very location-dependent,” explains Ryningen.

At the start of the project she carried out a literature study to find out how such dirt affected its surroundings, only to find out that existing research focusing on air pollution and dust particles had for the most part been directed on the human body. However, she did find examples of research into the ways in which sand storms impact on solar cells installed in the Middle East. In other words, more research was needed in order to provide scientists with more details about this subject.

“We’ve seen that some dust particles absorb light while others reflect it,” says Ryningen. “And small particles reflect more light than larger ones, whereas some scale contamination is biological and acts as a kind of ‘sun factor’,” she says. And some scale coatings are thicker than others.

However, what they all have in common is that they must be removed in order for the solar cells to function optimally according to specifications. For this reason, the researchers have developed a cleaning approach that is both fast and sensitive, as well as being environmentally-friendly. And which can deal with all the different types of contamination we encounter.

Cleaning is part of normal operations

The Norwegian company Scatec Solar constructs, owns, operates and maintains solar energy farms in many countries, including the Czech Republic, South Africa, Rwanda, Honduras and Jordan. Last year, the company’s sites generated as much as 791 GWh. This is equivalent to the consumption of 200,000 average EU households.

Project Manager Caroline Sissener at Scatec Solar describes the Norwegian researchers’ solution as interesting, especially for solar energy farms located in the Middle East.

“Cleaning is part of standard operational procedures at our solar energy farms, where equipment is cleaned at least once or twice a year on order to avoid soiling. This involves the removal of everything from sand to bird droppings ,” she says. “But cleaning frequency is location-dependent. If a farm is located in a desert environment, the panels will require more frequent cleaning because the solar cells become covered with soil and sand,” says Sissener.

She goes on to say that Scatec Solar often employs manual cleaning methods because these are effective and inexpensive, but that the company also uses automated systems.

“Cleaning robots may offer a relevant and attractive solution for solar energy parks located in areas where frequent cleaning is required,” says Sissener.

She also informs us that manual methods are important to Scatec in some situations because they provide local jobs. The method chosen is assessed on a case-by-case basis, and environmental factors such as water shortages and neighbouring agricultural activity are also taken into account.

Robot arm and micro-showers

The robot cleaner currently in SINTEF’s laboratory has undergone a range of tests. Researchers have experimented with a variety of micro cleaning pads, chemicals and air pressure application approaches – all tested, of course, on different types of soiling.

“It is vitally important that we don’t discharge chemical pollutants into the environment,” explains Ryningen. “So we’ve rejected the use of traditional cleaning agents and have ended up using unbelievably small micro-droplets of water that are “sprayed” onto the glass, almost as a vapour. Then the robot uses a micro cleaning pad that effectively removes the contaminant particles.

Because solar cells can be exposed to wear and tear, researchers have also been working hard to develop methods of controlling the pressure exerted by the robot’s cleaning arm.

“It is vital that the robot doesn’t scratch the sensitive glass surface. Even small scratches can reduce the efficiency of the solar cells,” explains Ryningen, adding that “in theory, this should work on windows as well, which will open up a broader market for us,” she says.

Read more at: https://phys.org/news/2017-06-energy-efficient-robot.html#jCp

Negev desert solar field uses water-free robotic cleaning system

At large solar plants, keeping surfaces of solar panels free from dust and sand is not just a matter of good housekeeping but of whether or not the plants can really make a difference to the communities they want to serve. In other words, keeping the panels clean especially in very dry areas may be a matter of solar plant effectiveness or ineffectiveness. Solar plant panels in deserts collect large quantities of dust. Recently, a solar park in Israel was provided with an answer to the problem.

The 20-acre Ketura Sun Solar Park in the Negev Desert (located in the hot southern stretch, which suffers from sandstorms and little rain) was introduced to a robotic cleaning process from an Israel-based company, Ecoppia. No water is needed for the cleanups. Instead, each night (cleaning typically takes place during the early hours of dark) 100 centrally controlled E4 robots, as they are called, go to work on the panels using microfibers and controlled air flow to push dirt off panels. The robots use gravitation to move the dust particles downwards and off the panels. They move along a rigid aluminum frame with wheels coated with polyurethane; there is no load on the solar panels’ surface.

Ecoppia designed the system to be water-free and energy-efficient. When not cleaning, the robots are locked to a docking station outside of the solar PV row. While docking, robot batteries are charged through their solar panel. The fleet can be remotely managed from a dashboard or mobile app.

Before the latest robotic cleaning process, Ketura Sun’s solar panels were only cleaned about nine times a year, in consideration of the expense involved in a labor-intensive, water-based cleaning process. Manual panel cleaning could take up to five days. As a result operations worked suboptimally and in the interim between cleaning cycles the park suffered electricity production degradation due to “soiling,” the term used to describe the accumulation of dirt and dust on photovoltaic solar panel surfaces.

Ecoppia, founded in 2013, is in the business of photovoltaic solar panel cleaning solutions The Ketura Sun solar park is jointly owned by Siemens AG and solar energy pioneer Arava Power. Founded in 2006, Arava Power has seven solar parks in production or development across the Negev, with a total production capacity of 80 MW. In 2009, Siemens AG acquired a 40 percent stake in Arava Power.

The park’s robot cleaning crew is yet another marker of interest by the solar industry in improved techniques for keeping panels clean and efficient. Last November, a Tokyo-based company, Sinfonia Technology, announced it developed a robot with camera and sensors that can move autonomously and clean solar panels at large-scale solar power plants. Its robot had another approach, with equipment including scrub brush, wiper and detergent; and sprinkling water stored in its tank.

Also in November, US-based SunPower announced the acquisition of Greenbotics, a company with panel cleaning products for large-scale solar power plants.

Read more at – https://techxplore.com/news/2014-04-negev-solar-field-water-free-robotic.html

Have a great day!

Dust Monitoring Equipment – providing equipment, services and training in dust fallout management to the mining industry.

Rain Water Tanks

DustWatch is determined to make an effort to save water and do what we can to conserve this precious resource.  Here is our new 2500 Litre, 660 gallon water rain water tank at our Piketberg offices. It also a security feature as this tank makes it difficult to get into the garden!

Rain Water Tank