A better way to pack natural gas into fuel tanks

 

Tue, 10/27/2015 - 7:25am Robert Sanders, UC Berkeley Flexible MOFs undergo a dramatic structural change when they adsorb methane, rapidly going from a nonporous to a highly porous material. This animated gif shows one pore of the material. Image: Jarad Mason/UC BerkeleyA new and innovative way to store methane could speed the development of natural gas-powered cars that don’t require the high pressures or cold temperatures of today’s compressed or liquefied natural gas vehicles. Natural gas is cleaner-burning than gasoline, and today there are more than 150,000 compressed natural gas (CNG) vehicles on the road in the U.S., most of them trucks and buses. But until manufacturers can find a way to pack more methane into a tank at lower pressures and temperatures, allowing for a greater driving range and less hassle at the pump, passenger cars are unlikely to adopt natural gas as a fuel. UC Berkeley chemists have now developed a porous and flexible material—a so-called metal-organic framework (MOF)—for storing methane that addresses these problems. The flexible MOF collapses when the methane is extracted to run the engine, but expands when the methane is pumped in at only moderate pressure, within the range produced by a home compressor. “You could potentially fill up at home,” said Jeffrey Long, a UC Berkeley professor of chemistry who led the project. The flexible MOF can be loaded with methane, the main ingredient of natural gas, at 35 to 65 times atmospheric pressure (500 to 900 psi), whereas compressed natural gas (CNG) vehicles compress natural gas into an empty tank under 250 atmospheres (3,600 psi). Liquefied natural gas (LNG) vehicles operate at lower pressures but require significant insulation in the tank system to maintain the natural gas at minus-162 degrees Celsius (minus-260 degrees Fahrenheit) so that it remains liquid. Next-gen NG vehicles Long said that next-generation natural gas vehicles will require a material that binds the methane and packs it more densely into the fuel tank, providing a larger driving range. One of the major problems has been finding a material that absorbs the methane at a relatively low pressure, such as 35 atmospheres, but gives it all up at a pressure where the engine can operate, between 5 and 6 atmospheres. MOFs, which have a lot of internal surface area to adsorb gases—that is, for gas molecules to stick to the internal surfaces of the pores—and store them at high density, are one of the most promising materials for adsorbed natural gas (ANG) storage. “This is a big advance both in terms of capacity and thermal management,” Long said. “With these new flexible MOFs, you can get to capacities beyond what was thought possible with rigid MOFs.” Among the other advantages of flexible MOFs, Long says, is that they do not heat up as much as other methane absorbers, so there is less cooling of the fuel required. “If you fill a tank that has adsorbent, such as activated charcoal, when the methane binds it releases heat,” he said. “With our material, some of that heat goes into changing the structure of the material, so you have less heat to dissipate, less heat to manage. You don’t have to have as much cooling technology associated with filling your tank.” The flexible MOF material could perhaps even be placed inside a balloon-like bag that stretches to accommodate the expanding MOF as methane is pumped in, so that some of the heat given off goes into stretching the bag. Long and his colleagues at the National Institute of Standards and Technology and in Europe will publish their findings online in Nature. Improving on-board natural-gas storage Natural gas from oil wells is one of the cheapest and cleanest fossil fuels today, used widely to heat homes as well as in manufacturing and to produce electricity. It has yet to be widely adopted in the transportation sector, however, because of the expensive and large on-board compressed fuel tanks. In addition, gasoline packs over three times the energy density per volume as natural gas, even when compressed to 3,600 psi, which results in natural gas vehicles with a shorter driving range per fill-up. In order to advance on-board natural gas storage, Ford Motor Company teamed up with UC Berkeley on this project, with funding from the Advanced Research Projects Agency–Energy (ARPA-E) of the U.S. Dept. of Energy. Ford is a leader in CNG/propane-prepped vehicles with more than 57,000 sold in the U.S. since 2009, more than all other major U.S. automakers combined. According to Mike Veenstra, of Ford’s research and advanced engineering group in Dearborn, Michigan, Ford recognized that ANG has the potential to lower the cost of on-board tanks, station compressors and fuel along with serving to increase natural gas-powered vehicle driving range within the limited cargo space. “Natural gas storage in porous materials provides the key advantage of being able to store significant amounts of natural gas at low pressures than compressed gas at the same conditions,” said Veenstra, the principal investigator of this ARPA-E project. “The advantage of low pressure is the benefit it provides both on-board the vehicle and off-board at the station. In addition, the low-pressure application facilitates novel concepts such as tanks with reduced wall thicknesses along with conformable concepts which aid in decreasing the need to achieve the equivalent volumetric capacity of compressed CNG at high pressure.” Long has been exploring MOFs as gas adsorbers for a decade, hoping to use them to capture carbon dioxide emitted from power plants or store hydrogen in hydrogen-fueled vehicles, or to catalyze gas reactions for industry. Last year, however, a study by UC Berkeley’s Berend Smit found that rigid MOFs have a limited capacity to store methane. Long and graduate student and first author Jarad Mason instead turned to flexible MOFs, noting that they behave better when methane is pumped in and out. The flexible MOFs they tested are based on cobalt and iron atoms dispersed throughout the structure, with links of benzenedipyrazolate (bdp). Both cobalt (bdp) and iron (bdp) are highly porous when expanded, but shrink to essentially no pores when collapsed. Their first experiments on these compounds already surpass the theoretical limits for rigid MOFs, Long said. This is a fundamental discovery that now needs a lot of engineering to find out how best to take advantage of these new adsorbent properties.” He and his colleagues are also now developing flexible MOFs to store hydrogen. Source: Univ. of California, Berkeley http://www.rdmag.com/news/2015/10/better-way-pack-natural-gas-fuel-tanks

"Voltaglue" sticks in the wet and hardens when voltage is applied

 

NTU Asst Prof Terry Steele (right) with his researcher Gao Feng have developed a glue that hardens when an electrical voltage is applied A glue that performs at a high-level in wet environments could bring about all sorts of possibilities in areas like surgical care and ship maintenance. A somewhat common approach to this problem has been trying to replicate the freakish ability of mussels to bind themselves to boats and jetties, but a team from Singapore's Nanyang Technological University is coming at it from a slightly different angle by developing a glue that hardens when an electrical charge is applied. As the team's lead scientist Professor Terry Steele points out, most glues don't work when they're wet, in the same way that sticky tape won't stick to a wet surface because the adhesive will stick to the water rather than the surface. Steele and his team have been at work for more than a year, crafting a new form of adhesive that can perform its job in wet conditions, such as underwater or in the human body. They used hydrogels comprising carbon molecules known as carbenes, which are grafted onto tree-shaped plastic surfaces called dendrimers. Applying an electrical charge kicks the carbenes into action and sees them hook onto any nearby surfaces. A particularly promising aspect of this approach is that the length of time the voltage is applied to the gel dictates how many of these hooks the carbenes create. This means by controlling the charge you control the hardness of the glue, and in turn, its suitability for different applications. The team call this process "electrocuring." "For example, if we are gluing metal panels underwater, we want it hard enough to stick for a long time," says Steele. "However, for medical applications, we want the glue to be more rubber-like so it wouldn’t cause any damage to the surrounding soft tissues." Another attribute that could prove a huge plus of the glue, which the team has nicknamed "Voltaglue," may be the ability to reverse the process. That is, to cancel out the glue's adhesive properties to allow for simple dismantling of ship parts, for example, negating the need for nuts and bolts. Steele and his team are now working to reduce the time it takes for the glue to harden, from around half a minute down to just a few seconds. They will also conduct further research into the possibilities of making it "reversible." The research was published in the journal Nature Communications. Source: Nanyang Technological University   http://www.gizmag.com/voltaglue-adhesive-underwater-electricity-voltage/39107/

Laser sniffs out toxic gases from afar: System can ID chemicals in atmosphere from a kilometer away

 

The new technology can discriminate one type of gas from another with greater specificity than most remote sensors -- even in complex mixtures of similar chemicals -- and under normal atmospheric pressure, something that wasn't thought possible before. The researchers say the technique could be used to test for radioactive byproducts from nuclear accidents or arms control treaty violations, for example, or for remote monitoring of smokestacks or factories for signs of air pollution or chemical weapons. "You could imagine setting this up around the perimeter of an area where soldiers are living, as a kind of trip wire for nerve gas," said lead author Henry Everitt, an Army scientist and adjunct professor of physics at Duke University. The technique uses a form of invisible light called terahertz radiation, or T-rays. Already used to detect tumors and screen airport passengers, T-rays fall between microwaves and infrared radiation on the electromagnetic spectrum. Zapping a gas molecule with a terahertz beam of just the right energy makes the molecule switch between alternate rotational states, producing a characteristic absorption spectrum "fingerprint," like the lines of a bar code. Terahertz sensors have been used for decades to identify trace gases in the dry, low-pressure conditions of interstellar space or in controlled conditions in the lab, where they are capable of unambiguous identification and ultra-sensitive, part-per-trillion detection. But until now, efforts to use the same technique to detect trace gases under normal atmospheric conditions have failed because the pressure and water vapor in the air smears and weakens the spectral fingerprint. In a study published in the journal Physical Review Applied, Everitt, Ohio State University physicist Frank De Lucia and colleagues have developed a way around this problem. Their approach works by blasting a cloud of gas with two beams at once. One is a steady terahertz beam, tuned to the specific rotational transition energy of the gas molecule they're looking for. The second beam comes from a laser, operating in the infrared, which emits light in high-speed pulses. At the U.S. Army Aviation and Missile Research, Development, and Engineering Center near Huntsville, Alabama, the researchers have installed a one-of-a-kind infrared laser. Manufactured by a company called STI Optronics, it's capable of firing dozens of pulses of infrared light a second, each of which is less than a billionth-of-a-second long. "It's kind of like whacking a molecule with an infrared sledgehammer," Everitt said. Normal atmospheric pressure still blurs the chemical "bar code" produced by the blast of the Terahertz beam, but the ultra-short pulses of light from the more powerful infrared laser knock the molecule out of equilibrium, causing the smeared absorption lines to flicker. "We just have to tune each beam to the wavelengths that match the type of molecule we're looking for, and if we see a change, we know it has to be that gas and nothing else," Everitt said. The researchers directed the two beams onto samples of methyl fluoride, methyl chloride and methyl bromide gases in the lab to determine what combination of laser settings would be required to detect trace amounts of these gases under different weather conditions. "Terahertz waves will only propagate so far before water vapor in the air absorbs them, which means the approach works a lot better on, say, a cold winter day than a hot summer day," Everitt said. The researchers say they are able to detect trace gases from up to one kilometer away. But even under ideal weather conditions, the technology isn't ready to be deployed in the field just yet. For one, converting an eight-foot, one-ton laser into something closer in size to a briefcase will take some time. Having demonstrated that the technique can work, their next step is to figure out how to tune the beams to detect additional gases. Initially, they plan to focus on toxic industrial chemicals such as ammonia, carbon disulfide, nitric acid and sulfuric acid. Eventually, the researchers say their technique could also be useful for law enforcement in detecting toxic gases generated by meth labs, and other situations where detection at the gas's source isn't feasible. "Point sensing at close range is always better than remote sensing if you can do it, but it's not always possible. These methods let us collect chemical intelligence that tells us what's going on before we get somewhere," Everitt said. The research was supported by grants from the Defense Threat Reduction Agency (DTRA) and the Defense Advanced Research Projects Agency (DARPA). Additional support was provided by the U.S. Army.

Transmission mechanism using magnetic levitating gear

 

Researchers from Universidad Carlos III de Madrid (UC3M) are developing a new transmission mechanism with no touching parts, based on magnetic forces which prevent friction and wear and make lubrication unnecessary. It can be applied in space travel and exploration but has also been adapted for use in other areas, such as the railroad and aircraft industries. This research is being carried out under the auspices of MAGDRIVE, a European research project coordinated by Professor José Luis Pérez Díaz, from the UC3M Instituto Pedro San Juan de Lastanosa, in which seven European entities participate. It consists of the development of a magnetic gear reducer, that is, a mechanism that transforms speed from an input axle to another in an output axle (as in a bicycle chain mechanism or the gearbox of an automobile). But in this case, unlike a conventional gear reducer, this transmission is produced without contact between the pieces thanks to the magnetism. One of its chief advantages is the absence of wear among the pieces, which makes lubrication unnecessary. As such, "the operating life of these devices can be much longer than the life of a conventional gear reducer with teeth, and can even work in cryogenic temperatures," notes one of the researchers, Efrén Díez Jiménez, from the UC3M Department of Mechanical Engineering. It can even continue to function after an event of overload. If the axle is blocked, "the parts simply slide amongst themselves, but nothing breaks." In addition, less noise is produced, vibration is reduced, and it is capable of through-wall transmission. A Gearbox that Levitates In addition to the contactless transmission, the axles are likewise contactless. "It is the first time in history that the input axle as well as the output axle of a gear reducer are floating without any kind of contact, and it can keep a mechanism which contains nothing else spinning at 3,000 revolutions per minute at cryogenic temperatures" says the main researcher on the project, José Luis Pérez Díaz. Although the main goal of the MAGDRIVE project is to build a prototype that can be used in extreme conditions in outer space, another one that can be used at room temperature has also been developed. For outer space, the cryogenic prototype has been developed. This type keeps the axles floating and it can work at a temperature of -210°C and in a vacuum. The mechanism integrates levitating superconductor bearings that generate stable forces of repulsion into its structure. This allows it to turn and, moreover, it stabilizes it against oscillating motion or possible imbalances. It is the first mechanism in history that does not have this type of friction. It has several applications in outer space, "from robot arms or antenna positioners, where high-precision movements are needed or when contamination from lubricants is undesired, to vehicles that, because of temperature or extreme conditions of absence of pressure, shorten the life of conventional mechanisms, as happens with the wheels of a Rover that has to go on Mars." The second prototype that has been developed can be used at room temperature. The magnetic reducer "substitutes the gear teeth with permanent magnets that repel and attract each other" so that "the transmission of couples and forces between the moving parts with contact is achieved," explains Efrén Díez Jiménez. Its applications can be transferred to any field where conventional mechanical reducers are used, such as self-propulsion, the railroad sector, the oil industry, or in mechanics and manufacturing in general, cite the researchers. Thanks to the absence of lubrication and oils, it can also be applied in the pharmaceutical, biomedical and food industries, where cleanliness requirements of are very strict. Although the cryogenic prototype was the global objective of the project because it solved the problem posed by the European Space Agency (ESA),"no doubt the room temperature prototype is the one that can have the biggest impact and industrial application," they conclude. The final results of the MAGDRIVE project have been presented at different conferences, congresses and meetings organized by ESA, NASA and ASME, generating a great deal of interest among participants. The researchers have published some of the results in the Journal of Engineering Tribology, among others. At present they are analyzing implementation of these types of systems in different industrial areas. And, the latest news: their research has been accepted for upcoming publication in the review Aerospace Science and Technology. Story Source: The above story is based on materials provided by Universidad Carlos III de Madrid - Oficina de Información Científica. Note: Materials may be edited for content and length.

Soon we could make all sorts of things from sawdust

 

Sawdust can be converted into a fuel additive – among other things – using a new chemical process (Photo: Rasbak)

 

This is science at its best: When I was growing up, the only practical use for sawdust was to soak up vomit, but thanks to scientists at a Belgian university who developed a new chemical process, that same sawdust could soon be used in gasoline and other products normally derived from petroleum.

Researchers at KU Leuven university’s Centre for Surface Chemistry and Catalysis have been able to take the cellulose in sawdust and convert it into hydrocarbon chains. These can be used as an additive in gasoline or as building blocks to create plastics, rubber, nylon, insulation foams and other materials normally made from ethylene, propylene and benzene.

"This is a new type of bio-refining, and we currently have a patent pending for it," says Dr. Bert Lagrain, co-author of a paper on the team's findings. "We have also built a chemical reactor in our lab: we feed sawdust collected from a sawmill into the reactor and add a catalyst – a substance that sets off and speeds the chemical reaction. With the right temperature and pressure, it takes about half a day to convert the cellulose in the wood shavings into saturated hydrocarbon chains, or alkanes."

The resulting product does not come out as fully-distilled gasoline – this requires one final step – but the researchers say their biomass-based product can be used as a green additive that replaces a "portion of traditionally-refined gasoline."

The researchers are also excited about the potential of cellulose to replace other products currently derived from petroleum, and its general abundance and accessibility. "Cellulose is available everywhere; it is essentially plant waste, meaning it does not compete with food crops in the way that first generation energy crops – crops grown for bioethanol, for example – do," says KU Leuven's Prof. Bert Sels.

The team's paper was recently published in the journal Energy & Environmental Science.

Source: KU Leuven

 

Self-healing polymer 'starfish' prolong lifetime of automotive oils

 

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Researchers have created self-healing polymers that could extend the lifetime of automotive oils. These polymers are suitable to add to lubricants and could maintain the physical properties of engine oils for longer, they claim helping engine efficiency. Biological materials, such as skin, self heal following damage giving inspiration for these new materials.

Polymers are often added to automotive oils to control important physical properties such as viscosity but mechanical and thermal stress can break the polymers decreasing the efficiency and how they affect the oils properties. The research team, led by Professor David Haddleton, of the University of Warwick have now designed a self-healing, star-shaped polymer for use as a viscosity modifier.

The methacrylate polymer has vulnerable long arms which be broken off if stressed reducing performance. The research team found they could add a particular chemical combination to the polymer’s backbone which, almost like a starfish, which allow broken arms to reform via a “Diels Alder cycloaddition reaction” in a self healing reaction.

The research team now plan to 'optimise the chemistry before passing it on to our industrial collaborators, Lubrizol, for development in automotive lubricant applications,' says Professor Haddleton.

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Story Source:

The above story is based on materials provided by University of Warwick. Note: Materials may be edited for content and length.

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Journal Reference:

1. Syrett et al. Self-healing polymers prepared via living radical polymerisation. Polymer Chemistry, 2010; DOI: 10.1039/b9py00316a

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