Thursday, November 17, 2011

The green look for electric vehicle charging stations

The network of electric-vehicle (EV) charging stations in Germany is still relatively sparse, but their number is growing rapidly. The majority of roadside charging points take the form of steel-clad pillars. A group of researchers has set out to develop an alternative design based on environmentally compatible materials.

Our cityscapes will soon be dominated by a new feature: EV charging points. At present they usually feature a steel- or aluminum-clad housing. Researchers at the Fraunhofer Institute for Mechanics of Materials IWM in Halle want to improve their green credentials. In collaboration with industrial partner Bosecker Verteilerbau Sachsen GmbH, they are developing an alternative solution based on eco-friendly materials. Their idea is to replace the steel cladding that protects cables, power outlets and electronic switchgear with honeycomb panels made of a wood-plastic composite (WPC). At present, the main application for this type of reconstituted wood product is weather-resistant decking for patios.

WPC is a natural fiber composite made up of 70 parts of cellulosic wood fiber derived from sustainable resources to 30 parts of thermoplastic polypropylene. Its advantages, apart from the high proportion of sustainable raw materials, are that it is 100% recyclable and contains no tropical timber. Wood-plastic composites can be repeatedly recycled into new products and have a neutral carbon footprint. As Sven Wüstenhagen, one of the IWM researchers in Halle, explains: "Trees extract huge quantities of carbon dioxide from the atmosphere as they grow, and sequester carbon in their ligneous fibers. It is therefore probable that the use of WPC in this new application will result in lower CO2 emissions compared with the use of steel."

Another advantage of the composite material, according to Wüstenhagen, is that its production is more energy-efficient than that of steel or other metal cladding materials. WPC is produced using an extrusion process that involves melting a mixture of wood fibers and thermoplastic resin under high pressure and at high temperature and feeding the resulting viscous product into a continuous mold. With modern processing technologies, the fibers can be added to the mixture in their natural state, without first being transformed into granulate, thus eliminating an energy-intensive intermediate stage and preserving the quality of the fibers. Because wood has a high thermal sensitivity, it has to be processed at temperatures below 200 degrees Celsius.

The housings are manufactured in the form of modular components that can be clipped together as required to create a wide variety of different designs, thus allowing them to blend in with the surrounding architecture. Their modular structure also enables the composite panels to be removed easily during repairs. Industrial design expert Wüstenhagen is already thinking about other possible new applications for the WPC components: "They could be used, for instance, to construct street furniture such as park benches or bus shelters. That's one of our next objectives. Another of our ideas is to integrate functional elements such as cable holders and cable management systems in the components for EV charging stations. This is a viable proposition because WPC can be formed into almost any shape, unlike the metal sheeting used in currently available housings."

Nonetheless, the WPC cladding has to live up to some very demanding requirements. It must be shatterproof and sufficiently elastic to withstand impact without damage, and it must be capable of resisting wide variations in temperature, high levels of humidity and prolonged UV exposure. The researchers are therefore testing samples of the material in a climate chamber to assess its resistance to extreme temperature conditions and determine which additives or types of coating provide the best weather protection. The IWM experts have almost completed their first prototype of the new WPC housing and are about to start outdoor testing. Sven Wüstenhagen and his team are confident that it won't be long before the first "all-green" EV charging stations appear on our streets.

Story Source:

The above story is reprinted from materials provided by Fraunhofer-Gesellschaft.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

How close is too close? Hydrofracking to access natural gas reservoirs poses risks to surface water, researchers say

Natural gas mining has drawn fire recently after claims that hydraulic fracturing, an increasingly popular technique for tapping hard-to-reach reservoirs, contaminates groundwater. Surface lakes, rivers and streams may also be at risk.

In an eView paper of Frontiers in Ecology and the Environment, researchers from the University of Central Arkansas, University of Arkansas and the Environmental Protection Agency estimate the average proximity of drill platforms to surface lakes and streams for two large shale basins underlying much of the eastern United States. They review available information on potential threats to surface waters, and conclude that policy makers have woefully little data to guide accelerating natural gas development.

Hydrofracking wells expose nearby streams to loose sediments and hazardous fracturing fluids, and draw away large amounts of water. The technique forces high pressure fluid into dense rock, creating cracks through which trapped natural gas escapes and can be collected from the drill shaft. Developed in the 1940s, the technique gained wide application in the 1990s as gas prices rose and technology to drill horizontally away from a vertical well shaft made "unconventional" drilling profitable. Demand is up for natural gas because it burns cleaner than coal or petroleum, producing less greenhouse gas and smog.

But concerns about toxic components of fracking fluids, such as diesel, lead, formaldehyde, and other organic solvents, are undermining the green reputation of natural gas. "What will happen as fracking doubles, triples, over the next 25 years? How should we set policy to protect resources and ecosystems?" the authors ask. "We don't have the data to decide. We need to generate it."

Story Source:

The above story is reprinted from materials provided by Ecological Society of America.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Sally Entrekin, Michelle Evans-White, Brent Johnson, Elisabeth Hagenbuch. Rapid expansion of natural gas development poses a threat to surface waters. Frontiers in Ecology and the Environment, 2011; 111006052617003 DOI: 10.1890/110053

Exploring the inner workings of materials

Van Vliet, awarded tenure this year as the Paul M. Cook Career Development Associate Professor of Materials Science and Engineering and Biological Engineering, says working on a farm during her summers in New Jersey is what initially sparked her interest. “Farmers are really creative engineers,” she explains: They rely on extremely complex machines, such as potato harvesters, and spend the off-season repairing them. In addition, she says, they are constantly dealing with experimental questions in biology — “questions like, how much nitrogen should there be in the soil for the pepper fruit to grow faster than the leaves?”

Even though her farm jobs often involved the lowliest of tasks — “one of my jobs at the Rutgers Agricultural Research and Extension Center was separating the rotten potatoes and the mud clumps from the good potatoes,” she recalls — “the people I worked with were very smart engineers. I learned about how things work, how complicated machines are made and repaired, and how people systematically ask and answer questions.”

Besides her farm experiences, Van Vliet says another turning point in her growing interest in technology was a stint at Space Camp, an educational program in Huntsville, Ala., when she was 13. That’s where, she says, “I got hooked on … really high-tech stuff.”

Those ways of thinking have carried into her academic research, which spans topics from the microscopic structure of concrete to detecting how cancer cells attract new blood vessels to foster their growth. A common thread throughout: the combining of computer models and lab experiments to understand how chemistry and mechanics are closely intertwined in materials that are important to human existence.

“I always enjoyed being challenged,” she says. “Like many here, I wanted to do something hard. Engineering seemed like it wouldn’t be easy.” Engineering related to biology and medicine in particular, she reasoned, “was something that sounded like you’d make a direct impact on people’s lives.”

Teaching was also a draw from an early age. Even as a child, Van Vliet recalls, “I always loved the idea of teaching.” In fact, she says, “I would give classes in my backyard — to nobody.” Mostly, these were “very rigorous cooking classes. I always wanted to have my own cooking show, explaining exactly why onion grass made such a great soup.”

During her senior year of high school, Van Vliet was in a serious car accident, experiencing what is now termed traumatic brain injury. With much support, she was able to apply to colleges from her rehabilitation facility, and graduate from high school with her class that spring.

While both her parents are college graduates — her father worked at DuPont, and her mother taught Spanish — the idea of going away to college for engineering was “a new idea to all of us,” she says. Van Vliet chose Brown University because it offered degrees in both biomedical engineering and bioethics, enjoying her undergraduate experience so much that she thought she wanted to stay at Brown for graduate school as well. She loved “the pace of the lab work — every day, solving a problem or making progress.” But her professors encouraged her to expand her horizons.

Van Vliet applied, somewhat tentatively, to MIT’s doctoral program in materials science and engineering. “I wasn’t even going to visit,” she recalls. “I wanted to be surrounded by people who like to play sports, to do African dance, debate philosophy,” she says, and she figured MIT “would be all geeks and nerds.”

But she received a phone call from Kirk Kolenbrander, who was then on MIT’s materials science and engineering faculty (and is now vice president and secretary of the Corporation), urging her to make a visit and even explaining which bus and subway stations to use.

So Van Vliet did end up venturing north to Cambridge, and has vivid memories of that weekend — where, among other things, she met her future husband. She recalls “how much I was impressed by the enthusiasm, the breadth of intelligence” that she found, and how the students seemed “fun and well-rounded.”

And, she adds: “I now love the geeky facets of MIT life, and I actively contribute to that!”

Van Vliet enrolled at the Institute, earning her PhD in just four years with a 2002 thesis on predicting defect nucleation in metals. Upon completing her degree, she accepted MIT’s offer of a faculty position in the Department of Materials Science and Engineering. But first she spent two years as a postdoc at Children’s Hospital Boston, researching how mechanical strain regulates chemical activity of enzymes related to the growth of blood vessels, before returning to MIT as an assistant professor in 2004.

She continues to conduct research on material chemomechanics, which she describes as “the coupling between chemistry and mechanics.” Her group has described how tissue cells respond to changes in their mechanical and chemical environments — including changes that may lead to the onset of cancer — by studying nonbiological materials that share this chemical-mechanical coupling: polymers that can mimic some properties of tissues, nanocomposite coatings that can improve the toughness of car bodies, and even cement-based materials in which water confined in small pores can control mechanical properties.

Because her work is so inherently multidisciplinary, she says, “I get to populate our group with students and postdocs from all kinds of disciplines — and engineering, biological engineering, mechanical engineering, solid-state physics, chemistry. It’s a very diverse group of talent. That’s part of our strength, and part of MIT’s strength.”
This story is republished courtesy of MIT News (, a popular site that covers news about MIT research, innovation and teaching.

Provided by Massachusetts Institute of Technology (news : web)

Giant flakes make graphene oxide gel: Discovery could boost metamaterials, high-strength fibers

Giant flakes of graphene oxide in water aggregate like a stack of pancakes, but infinitely thinner, and in the process gain characteristics that materials scientists may find delicious.

A new paper by scientists at Rice University and the University of Colorado details how slices of graphene, the single-atom form of carbon, in a solution arrange themselves to form a nematic liquid crystal in which particles are free-floating but aligned.

That much was already known. The new twist is that if the flakes -- in this case, graphene oxide -- are big enough and concentrated enough, they retain their alignment as they form a gel. That gel is a handy precursor for manufacturing metamaterials or fibers with unique mechanical and electronic properties.

The team reported its discovery online this week in the Royal Society of Chemistry journal Soft Matter. Rice authors include Matteo Pasquali, a professor of chemical and biomolecular engineering and of chemistry; James Tour, the T.T. and W.F. Chao Chair in Chemistry as well as a professor of mechanical engineering and materials science and of computer science; postdoctoral research associate Dmitry Kosynkin; and graduate students Budhadipta Dan and Natnael Behabtu. Ivan Smalyukh, an assistant professor of physics at the University of Colorado at Boulder, led research for his group, in which Dan served as a visiting scientist.

"Graphene materials and fluid phases are a great research area," Pasquali said. "From the fundamental point of view, fluid phases comprising flakes are relatively unexplored, and certainly so when the flakes have important electronic properties.

"From the application standpoint, graphene and graphene oxide can be important building blocks in such areas as flexible electronics and conductive and high-strength materials, and can serve as templates for ordering plasmonic structures," he said.

By "giant," the researchers referred to irregular flakes of graphene oxide up to 10,000 times as wide as they are high. (That's still impossibly small: on average, roughly 12 microns wide and less than a nanometer high.) Previous studies showed smaller bits of pristine graphene suspended in acid would form a liquid crystal and that graphene oxide would do likewise in other solutions, including water.

This time the team discovered that if the flakes are big enough and concentrated enough, the solution becomes semisolid. When they constrained the gel to a thin pipette and evaporated some of the water, the graphene oxide flakes got closer to each other and stacked up spontaneously, although imperfectly.

"The exciting part for me is the spontaneous ordering of graphene oxide into a liquid crystal, which nobody had observed before," said Behabtu, a member of Pasquali's lab. "It's still a liquid, but it's ordered. That's useful to make fibers, but it could also induce order on other particles like nanorods."

He said it would be a simple matter to heat the concentrated gel and extrude it into something like carbon fiber, with enhanced properties provided by "mix-ins."

Testing the possibilities, the researchers mixed gold microtriangles and glass microrods into the solution, and found both were effectively forced to line up with the pancaking flakes. Their inclusion also helped the team get visual confirmation of the flakes' orientation.

The process offers the possibility of the large-scale ordering and alignment of such plasmonic particles as gold, silver and palladium nanorods, important components in optoelectronic devices and metamaterials, they reported.

Behabtu added that heating the gel "crosslinks the flakes, and that's good for mechanical strength. You can even heat graphene oxide enough to reduce it, stripping out the oxygen and turning it back into graphite."

Co-authors of the paper are Angel Martinez and Julian Evans, graduate students of Smalyukh at the University of Colorado at Boulder.

The Institute for Complex Adaptive Matter, the Colorado Renewable and Sustainable Energy Initiative, the National Science Foundation, the Air Force Research Lab, the Air Force Office of Scientific Research, the Welch Foundation, the U.S. Army Corps of Engineers Environmental Quality and Installation Program and M-I Swaco supported the research.

Story Source:

The above story is reprinted from materials provided by Rice University.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Budhadipta Dan, Natnael Behabtu, Angel Martinez, Julian S. Evans, Dmitry V. Kosynkin, James M. Tour, Matteo Pasquali, Ivan I. Smalyukh. Liquid crystals of aqueous, giant graphene oxide flakes. Soft Matter, 2011; DOI: 10.1039/C1SM06418E