Archive for August 2010
You are browsing the archives of 2010 August.
You are browsing the archives of 2010 August.
Weddings, vacation, illness, travel days . . . Looking back, sometimes there have been events that caused us to miss a few good ceramic- and glass-related developments and press releases. The stories in this grab bag have only a few cobwebs on them, so check ‘em out:
and, a video from Onyx Solar: Paving the way for building integrated photovoltaics:
A research group from the University of Campinas (Brazil) led by Fernando Galembeck thinks this air-based power source can be harnessed into a significant supply of electricity for a variety of consumers and lessen the dangers of lightening. “Our research could pave the way for turning electricity from the atmosphere into an alternative energy source for the future,” says Galembeck. “If we know how electricity builds up and spreads in the atmosphere, we can also prevent death and damage caused by lightning strikes.” He delivered the report at a meeting of the American Chemical Society.
Electricity in the air is formed when water vapor collects on microscopic particles of dust and other airborne materials. Galembeck has been studing electricity in the air for some time.
Recently, his group used particles of silica and aluminum phosphate, both common in the atmosphere, and according to Galembeck, found that that silica becomes negatively charged in high humidity and aluminum phosphate becomes more positively charged. They also found “clear evidence that water in the atmosphere can accumulate electrical charges and transfer them to other materials it comes into contact with,” says Galembeck. “We are calling this ‘hygroelectricity,’ meaning ‘humidity electricity’.”
Some of the groups work is discussed in a letter in a recent edition of Langmuir.
Galembeck describes the concept of special photovoltaic-like collectors that could capture hygroelectricity and route it to homes and businesses. He adds that hygroelectrical panels would best in geographic regions with high humidity.
His group also envisions using the panels to prevent the formation of lightning. They believe that hygroelectrical panels on top of buildings could drain electricity out of the air, and prevent the building of electrical charge that is released in lightning.
He says the next step is to find materials with the greatest potential for use.
“These are fascinating ideas that new studies by ourselves and by other scientific teams suggest are now possible,” Galembeck said. “We certainly have a long way to go. But the benefits in the long range of harnessing hygroelectricity could be substantial.”
The American Chemical Society today distributed a story that came out of one of its meetings regarding the use of “dry water” powder as a medium for absorbing CO2, enhancing certain chemical reactions and storing emulsions. Although the story is interesting, it’s not exactly clear to me if the CO2 angle, which is the one being played up, is really news. But, here is the scoop anyway.
The background to this is that Andrew Cooper and his group at the University of Liverpool have been playing around with uses for dry water for several years. Dry water is really just tiny water droplets that have been given a coating of hydrophobic fumed silica, except that it sort of looks like fine sand or sugar. What goes on with the creation of dry water is akin to the phenomenon one sees if a water droplet fall onto powdered mud: The water droplet balls up and has a visible coating of the dust.
Making dry water (DW) is apparently simple enough. It basically requires putting a mixture of water and hydrophobic fumed silica (19:1, by mass) in an ordinary blender.
Back in 2008, Cooper and his researchers gained some notoriety because they successfully demonstrated that DW could be used to store methane (in the form of methane gas hydrate) in a powder form if kept at low temperatures (-70°C) or under pressure.
The thinking of Cooper and others in his group at the time was that since the DW/methane gas hydrate combo can be easily made, it could be used to store and transport large amounts of methane for use, for example, in cars. They said that in 30 minutes a liter of methane gas could be stored in just 6 grams of DW.
But, even then, they also described the use of DW as an absorbent for CO2.
Cooper et al. also published an update on DW in late 2009, describing a method of making the DW perform as a gas separator and be recyclable by including a gelling agent.
So, the thrust of today’s story is that Cooper argues that DW is being overlooked as a piece of solving the CO2 accumulation problem. According to the ACS release, “Cooper and coworkers found that dry water absorbed over three times as much carbon dioxide as ordinary, uncombined water and silica in the same space of time. This ability to absorb large amounts of carbon dioxide gas as a hydrate could make it useful in helping to reduce global warming, the scientists suggested.”
But, like I said, I am not sure what the news is here.
Perhaps its more newsworthy that Cooper also described two new applications for DW:
According to a University of Connecticut press release, researchers believe they have developed a new material that could be used as a catalyst in alternative fuel development.
Featured in the September issue of the nanotechnology journal, Small, University of Connecticut chemistry professor Steven Suib describes a method developed for the production of a nanosized crystalline material that can potentially be used for energy conservation.
The material, sized at 100 nanometers, consists of two materials, one a template and the other a material that can grow around it in a well-ordered array. The growth can be controlled and its photocatalytic properties may be useful to drive reactions such as the splitting of water into hydrogen and oxygen.
According to Suib, the material can be a component of paint or can be applied to a surface, and will be useful in solar applications.
“It’s very hard to make materials this size,” Suib says, “as small antennas come in and out of a surface that small.”
Suib’s work with catalysts also expands to new oxygen reduction catalysts composed of octahedral molecular sieves of the the gamma form of manganese oxide (gamma-MnO2) and a small amount of titanium. We published a story on this work with active oxidation catalyst for Li-air batteries, which can be seen here.
The cost and performance problems with these existing systems are unfortunate, especially when it comes to photovoltaic solar panels and mirrors, particularly when one considers that many utility-scale solar energy systems are being located in desert areas that are prone to large amounts of non-organic dust. In some of these regions, even dragging out a hose or water truck to rinse off PV panels and mirrors is not practical nor economically feasible.
The effects of the dust on these solar energy system are tangible. “A dust layer of one-seventh of an ounce per square yard decreases solar power conversion by 40 percent,” explains MIT visiting professor Malay K. Mazumder. “In Arizona, dust is deposited each month at about four times that amount. Deposition rates are even higher in the Middle East, Australia and India.”
Mazumder knows something about dust. He has worked with NASA on a similar but more difficult problem: Extraterrestrial dust. When the problem is dust on surfaces somewhere lacking Earth’s atmosphere and weather – say, Mars or the moon – terrestrial technology just won’t cut it. Lunar dust was nasty stuff for astronauts to deal with and is described as tiny pieces, sharp and interlocking pieces of glass or coral that is everywhere on the lunar surface.
According to NASA, Mars dust isn’t quite so bad, but still a big problem:
Dust is also ubiquitous on Mars, although Mars dust is probably not as sharp as moon dust. Weathering smooths the edges. Nevertheless, Martian dust storms whip these particles 50 m/s (100+ mph), scouring and wearing every exposed surface. As the rovers Spirit and Opportunity have revealed, Mars dust (like moon dust) is probably electrically charged. It clings to solar panels, blocks sunlight and reduces the amount of power that can be generated for a surface mission.
NASA knew that dust interference with solar panel function could be catastrophic for Mars missions. Working with the agency, Mazumder and other researchers developed a novel self-cleaning solar panel technology for use in lunar and Mars missions.
Now, Mazumder says the time has come to apply the same technology on earth. “Solar panels powering rovers and future manned and robotic [NASA] missions must not succumb to dust deposition. But neither should the solar panels here on Earth,” he says
Mazumder describes the technology he has in mind as having three parts. The first part is thin layer of transparent, electrically sensitive material on the glass or plastic covering of a solar panel. The second part is a sensor to monitor dust levels on the surface of the panel. The third part is a system to send a brief electric charges over the surface of the panel. Because, like the stuff on moon and Mars, most Earth dust carries an electrical charge, delivering alternating electric fields acting through the thin layer on the panel dislodges, carries and deposits dust particles off and away from surfaces.
According to a news release, Mazumder says a two-minute process removes about 90 percent of the dust deposited on a solar panel. Further, his approach requires only a small amount of electric power, which can easily be supplied by the panel.