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  • richardmitnick 8:14 pm on September 21, 2014 Permalink | Reply
    Tags: , , Energy,   

    From M.I.T.: “Magnetic fields make the excitons go ’round” 


    MIT News

    September 21, 2014
    David L. Chandler | MIT News Office

    A major limitation in the performance of solar cells happens within the photovoltaic material itself: When photons strike the molecules of a solar cell, they transfer their energy, producing quasi-particles called excitons — an energized state of molecules. That energized state can hop from one molecule to the next until it’s transferred to electrons in a wire, which can light up a bulb or turn a motor.

    temp

    But as the excitons hop through the material, they are prone to getting stuck in minuscule defects, or traps — causing them to release their energy as wasted light.

    Now a team of researchers at MIT and Harvard University has found a way of rendering excitons immune to these traps, possibly improving photovoltaic devices’ efficiency. The work is described in a paper in the journal Nature Materials.

    Their approach is based on recent research on exotic electronic states known as topological insulators, in which the bulk of a material is an electrical insulator — that is, it does not allow electrons to move freely — while its surface is a good conductor.

    The MIT-Harvard team used this underlying principle, called topological protection, but applied it to excitons instead of electrons, explains lead author Joel Yuen, a postdoc in MIT’s Center for Excitonics, part of the Research Laboratory of Electronics. Topological protection, he says, “has been a very popular idea in the physics and materials communities in the last few years,” and has been successfully applied to both electronic and photonic materials.

    Moving on the surface

    Topological excitons would move only at the surface of a material, Yuen explains, with the direction of their motion determined by the direction of an applied magnetic field. In that respect, their behavior is similar to that of topological electrons or photons.

    In its theoretical analysis, the team studied the behavior of excitons in an organic material, a porphyrin thin film, and determined that their motion through the material would be immune to the kind of defects that tend to trap excitons in conventional solar cells.

    The choice of porphyrin for this analysis was based on the fact that it is a well-known and widely studied family of materials, says co-author Semion Saikin, a postdoc at Harvard and an affiliate of the Center for Excitonics. The next step, he says, will be to extend the analysis to other kinds of materials.

    por
    Structure of porphine, the simplest porphyrin

    While the work so far has been theoretical, experimentalists are eager to pursue the concept. Ultimately, this approach could lead to novel circuits that are similar to electronic devices but based on controlling the flow of excitons rather that electrons, Yuen says. “If there are ever excitonic circuits,” he says, “this could be the mechanism” that governs their functioning. But the likely first application of the work would be in creating solar cells that are less vulnerable to the trapping of excitons.

    Eric Bittner, a professor of chemistry at the University of Houston who was not associated with this work, says, “The work is interesting on both the fundamental and practical levels. On the fundamental side, it is intriguing that one may be able to create excitonic materials with topological properties. This opens a new avenue for both theoretical and experimental work. … On the practical side, the interesting properties of these materials and the fact that we’re talking about pretty simple starting components — porphyrin thin films — makes them novel materials for new devices.”

    The work received support from the U.S. Department of Energy and the Defense Threat Reduction Agency. Norman Yao, a graduate student at Harvard, was also a co-author.

    See the full article here.

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  • richardmitnick 7:53 pm on September 21, 2014 Permalink | Reply
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    From M.I.T.: “New formulation leads to improved liquid battery” 


    MIT News

    September 21, 2014
    David L. Chandler | MIT News Office

    Cheaper, longer-lasting materials could enable batteries that make wind and solar energy more competitive.

    temp

    Researchers at MIT have improved a proposed liquid battery system that could enable renewable energy sources to compete with conventional power plants.

    Donald Sadoway and colleagues have already started a company to produce electrical-grid-scale liquid batteries, whose layers of molten material automatically separate due to their differing densities. But the new formula — published in the journal Nature by Sadoway, former postdocs Kangli Wang and Kai Jiang, and seven others — substitutes different metals for the molten layers used in a battery previously developed by the team.

    Sadoway, the John F. Elliott Professor of Materials Chemistry, says the new formula allows the battery to work at a temperature more than 200 degrees Celsius lower than the previous formulation. In addition to the lower operating temperature, which should simplify the battery’s design and extend its working life, the new formulation will be less expensive to make, he says.

    The battery uses two layers of molten metal, separated by a layer of molten salt that acts as the battery’s electrolyte (the layer that charged particles pass through as the battery is charged or discharged). Because each of the three materials has a different density, they naturally separate into layers, like oil floating on water.

    The original system, using magnesium for one of the battery’s electrodes and antimony for the other, required an operating temperature of 700 C. But with the new formulation, with one electrode made of lithium and the other a mixture of lead and antimony, the battery can operate at temperatures of 450 to 500 C.

    Extensive testing has shown that even after 10 years of daily charging and discharging, the system should retain about 85 percent of its initial efficiency — a key factor in making such a technology an attractive investment for electric utilities.

    Currently, the only widely used system for utility-scale storage of electricity is pumped hydro, in which water is pumped uphill to a storage reservoir when excess power is available, and then flows back down through a turbine to generate power when it is needed. Such systems can be used to match the intermittent production of power from irregular sources, such as wind and solar power, with variations in demand. Because of inevitable losses from the friction in pumps and turbines, such systems return about 70 percent of the power that is put into them (which is called the “round-trip efficiency”).

    Sadoway says his team’s new liquid-battery system can already deliver the same 70 percent efficiency, and with further refinements may be able to do better. And unlike pumped hydro systems — which are only feasible in locations with sufficient water and an available hillside — the liquid batteries could be built virtually anywhere, and at virtually any size. “The fact that we don’t need a mountain, and we don’t need lots of water, could give us a decisive advantage,” Sadoway says.

    The biggest surprise for the researchers was that the antimony-lead electrode performed so well. They found that while antimony could produce a high operating voltage, and lead gave a low melting point, a mixture of the two combined both advantages, with a voltage as high as antimony alone, and a melting point between that of the two constituents — contrary to expectations that lowering the melting point would come at the expense of also reducing the voltage.

    “We hoped [the characteristics of the two metals] would be nonlinear,” Sadoway says — that is, that the operating voltage would not end up halfway between that of the two individual metals. “They proved to be [nonlinear], but beyond our imagination. There was no decline in the voltage. That was a stunner for us.”

    Not only did that provide significantly improved materials for the group’s battery system, but it opens up whole new avenues of research, Sadoway says. Going forward, the team will continue to search for other combinations of metals that might provide even lower-temperature, lower-cost, and higher-performance systems. “Now we understand that liquid metals bond in ways that we didn’t understand before,” he says.

    With this fortuitous finding, Sadoway says, “Nature tapped us on the shoulder and said, ‘You know, there’s a better way!’” And because there has been little commercial interest in exploring the properties and potential uses of liquid metals and alloys of the type that are most attractive as electrodes for liquid metal batteries, he says, “I think there’s still room for major discoveries in this field.”

    Robert Metcalfe, professor of innovation at the University of Texas at Austin, who was not involved in this work, says, “The Internet gave us cheap and clean connectivity using many kinds of digital storage. Similarly, we will solve cheap and clean energy with many kinds of storage. Energy storage will absorb the increasing randomness of energy supply and demand, shaving peaks, increasing availability, improving efficiency, lowering costs.”

    Metcalfe adds that Sadoway’s approach to storage using liquid metals “is very promising.”

    The research was supported by the U.S. Department of Energy’s Advanced Research Projects Agency-Energy and by French energy company Total.

    See the full article here.

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  • richardmitnick 1:46 pm on August 26, 2014 Permalink | Reply
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    From Berkeley Lab: “Competition for Graphene” 

    Berkeley Logo

    Berkeley Lab

    August 26, 2014
    Lynn Yarris (510) 486-5375

    A new argument has just been added to the growing case for graphene being bumped off its pedestal as the next big thing in the high-tech world by the two-dimensional semiconductors known as MX2 materials. An international collaboration of researchers led by a scientist with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) has reported the first experimental observation of ultrafast charge transfer in photo-excited MX2 materials. The recorded charge transfer time clocked in at under 50 femtoseconds, comparable to the fastest times recorded for organic photovoltaics.

    “We’ve demonstrated, for the first time, efficient charge transfer in MX2 heterostructures through combined photoluminescence mapping and transient absorption measurements,” says Feng Wang, a condensed matter physicist with Berkeley Lab’s Materials Sciences Division and the University of California (UC) Berkeley’s Physics Department. “Having quantitatively determined charge transfer time to be less than 50 femtoseconds, our study suggests that MX2 heterostructures, with their remarkable electrical and optical properties and the rapid development of large-area synthesis, hold great promise for future photonic and optoelectronic applications.”

    fw
    Feng Wang is a condensed matter physicist with Berkeley Lab’s Materials Sciences Division and UC Berkeley’s Physics Department. (Photo by Roy Kaltschmidt)

    Wang is the corresponding author of a paper in Nature Nanotechnology describing this research. The paper is titled Ultrafast charge transfer in atomically thin MoS2/WS2 heterostructures. Co-authors are Xiaoping Hong, Jonghwan Kim, Su-Fei Shi, Yu Zhang, Chenhao Jin, Yinghui Sun, Sefaattin Tongay, Junqiao Wu and Yanfeng Zhang.

    MX2 monolayers consist of a single layer of transition metal atoms, such as molybdenum (Mo) or tungsten (W), sandwiched between two layers of chalcogen atoms, such as sulfur (S). The resulting heterostructure is bound by the relatively weak intermolecular attraction known as the van der Waals force. These 2D semiconductors feature the same hexagonal “honeycombed” structure as graphene and superfast electrical conductance, but, unlike graphene, they have natural energy band-gaps. This facilitates their application in transistors and other electronic devices because, unlike graphene, their electrical conductance can be switched off.

    “Combining different MX2 layers together allows one to control their physical properties,” says Wang, who is also an investigator with the Kavli Energy NanoSciences Institute (Kavli-ENSI). “For example, the combination of MoS2 and WS2 forms a type-II semiconductor that enables fast charge separation. The separation of photoexcited electrons and holes is essential for driving an electrical current in a photodetector or solar cell.”

    In demonstrating the ultrafast charge separation capabilities of atomically thin samples of MoS2/WS2 heterostructures, Wang and his collaborators have opened up potentially rich new avenues, not only for photonics and optoelectronics, but also for photovoltaics.

    photo
    Photoluminescence mapping of a MoS2/WS2 heterostructure with the color scale representing photoluminescence intensity shows strong quenching of the MoS2 photoluminescence. (Image courtesy of Feng Wang group)

    “MX2 semiconductors have extremely strong optical absorption properties and compared with organic photovoltaic materials, have a crystalline structure and better electrical transport properties,” Wang says. “Factor in a femtosecond charge transfer rate and MX2 semiconductors provide an ideal way to spatially separate electrons and holes for electrical collection and utilization.”

    Wang and his colleagues are studying the microscopic origins of charge transfer in MX2 heterostructures and the variation in charge transfer rates between different MX2 materials.

    “We’re also interested in controlling the charge transfer process with external electrical fields as a means of utilizing MX2 heterostructures in photovoltaic devices,” Wang says.

    This research was supported by an Early Career Research Award from the DOE Office of Science through UC Berkeley, and by funding agencies in China through the Peking University in Beijing.

    See the full article here.

    A U.S. Department of Energy National Laboratory Operated by the University of California

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  • richardmitnick 1:38 pm on July 28, 2014 Permalink | Reply
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    From Berkeley Lab: “Cagey Material Acts as Alcohol Factory” 

    Berkeley Logo

    Berkeley Lab

    July 28, 2014
    Kate Greene

    Some chemical conversions are harder than others. Refining natural gas into an easy-to-transport, easy-to-store liquid alcohol has so far been a logistic and economic challenge. But now, a new material, designed and patented by researchers at Lawrence Berkeley National Laboratory (Berkeley Lab), is making this process a little easier. The research, published earlier this year in Nature Chemistry, could pave the way for the adoption of cheaper, cleaner-burning fuels.

    “Hydrocarbons like ethane and methane could be used as fuel, but they’re hard to store and transport because they’re gases,” says Dianne Xiao, graduate student at the University of California Berkeley. “But if you have a catalyst that can selectively turn them into alcohols, which are much easier to transfer and store,” she says. “that would make things a lot easier.”

    Xiao and Jeffrey Long, scientist in Berkeley Lab’s Materials Sciences Division and professor of chemistry at the UC Berkeley focused this project on converting ethane to ethanol.

    two
    Jeff Long, Materials Sciences scientist, with student Dianne Xiao. The team’s research enabled MOFs to oxidize ethane to ethanol. Credit: Roy Kaltschmidt

    Ethanol is a potential alternative fuel that burns cleaner and has a higher energy density than other alternative fuels like methanol. One problem with ethanol, however, is that current methods for production require extreme heat, which makes it expensive.

    The innovation came when Long and Xiao designed a material called Fe-MOF-74, in a class of materials called metal-organic frameworks or MOFs. Because of their cage-shaped structures, MOFs boast a high surface area, which mean they can absorb extremely large amounts of gas or liquid compared to the weight of the MOF itself.

    Since MOFs are essentially structured like a collection of tiny cages, they can capture other molecules, acting as a filter. Additionally, they can perform chemistry as molecules pass through the cages, becoming little chemical factories that convert one substance to another.

    It’s this chemical-conversion feature of MOFs that Long and Xiao took advantage of. Ethane is a molecule made of two carbon atoms where each atom is surrounded by atoms of hydrogen. Ethanol is also made of two carbon atoms bonded to hydrogen atoms, but one of its carbon atoms is also bonded to a hydrogen-oxygen ion called a hydroxyl.

    hex
    A view inside the MOF: hexagonal channels lined with iron. Credit: Dianne Xiao, Berkeley

    Previous attempts to add a hydroxyl ion to ethane to make ethanol have required high pressure and high temperatures that range from 200 to 300 degrees Celsius. It’s costly and inconvenient.

    But by using a specially designed MOF—one in which a kind of iron was added inside the tiny molecular cages—the researchers were able to reduce the need for extreme heat, converting ethane to alcohol at just 75 degrees Celsius.

    “This is getting toward a holy grail in chemistry which is to be able to cleanly take alkanes to alcohols without a lot of energy,” says Long. Long and Xiao worked closely with researchers at the National Institute of Standards and Technology, the University of Minnesota, the University of Delaware, and the University of Turin to design, model, and characterize the MOF and resultant ethanol production.

    Next steps involve tweaking the concentrations of iron in the MOF to produce a more efficient conversion, says Xiao. “It’s a promising proof of principle,” she says. “It’s exciting that we can do this now at low temperature and low pressures.”

    This research was funded by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. Reactivity studies were supported by the Laboratory Directed Research and Development Program of Lawrence Berkeley National Laboratory. Work at the Molecular Foundry and experiments performed at the Advanced Light Source were funded by the DOE’s Office of Basic Energy Sciences.

    A U.S. Department of Energy National Laboratory Operated by the University of California

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  • richardmitnick 6:11 am on July 22, 2014 Permalink | Reply
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    From ESO: “Solar Farm to be Installed at La Silla” 


    European Southern Observatory

    21 July 2014
    Roberto Tamai
    E-ELT Programme Manager
    Garching bei München, Germany
    Tel: +49 89 3200 6367
    Email: rtamai@eso.org

    Lars Lindberg Christensen
    Head of ESO ePOD
    ESO ePOD, Garching, Germany
    Tel: +49 89 3200 6761
    Cellular: +49 173 3872 621
    E-mail: lars@eso.org

    As part of its green initiatives, ESO has signed an agreement with the Chilean company, Astronomy and Energy (a subsidiary of the Spanish LKS Group), to install a solar farm at the La Silla Observatory. ESO has been working on green solutions for supplying energy to its sites for several years, and these are now coming to fruition. Looking to the future, renewables are considered vital to satisfy energy needs in a sustainable manner.

    ESO LaSilla
    ESO at LaSilla

    solar

    ESO’s ambitious programme is focused on achieving the highest quality of astronomical research. This requires the design, construction and operation of the most powerful ground-based observing facilities in the world. However, the operations at ESO’s observatories present significant challenges in terms of their energy usage.

    Despite the abundance of sunshine at the ESO sites, it has not been possible up to now to make efficient use of this natural source of power. Astronomy and Energy will supply a means of effectively exploiting solar energy using crystalline photovoltaic modules (solar panels), which will be installed at La Silla.

    The installation will cover an area of more than 100 000 square metres, with the aim of being ready to supply the site by end of the year.

    The global landscape for energy has changed considerably over the last 20 years. As energy prices are increasing and vary unpredictably, ESO has been keen to look into ways to control its energy costs and also limit its ecological impact. The organisation has already managed to successfully reduce its power consumption at La Silla, and despite the additions of the VISTA and VST survey telescopes, power use has remained stable over the past few years at the Paranal Observatory, site of the VLT.

    ESO Vista Telescope
    ESO VISTA Telescope

    ESO VST telescope
    ESO VST Telescope

    The much-improved efficiency of solar cells has meant they have become a viable alternative to exploit solar energy. Solar cells of the latest generation are considered to be very reliable and almost maintenance-free, characteristics that contribute to a high availability of electric power, as required at astronomical observatories.

    As ESO looks to the future, it seeks further sustainable energy sources to be compatible across all its sites, including Cerro Armazones — close to Cerro Paranal and the site of the future European Extremely Large Telescope (E-ELT). This goal will be pursued not only by installing primary sources of renewable energy, as at La Silla, but also by realising connections to the Chilean interconnected power systems, where non-conventional renewable energy sources are going to constitute an ever-growing share of the power and energy mixes.

    The installation of a solar farm at La Silla is one of a series of initiatives ESO is taking to tackle the environmental impacts of its operations, as can be viewed here. Green energy is strongly supported by the Chilean government, which aims to increase the Chilean green energy share to 25% in 2020, with a possible target of 30% by 2030.

    See the full article, with note, here.

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    ESO, European Southern Observatory, builds and operates a suite of the world’s most advanced ground-based astronomical telescopes.


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  • richardmitnick 12:19 pm on July 15, 2014 Permalink | Reply
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    From PPPL: “Experts assemble at PPPL to discuss mitigation of tokamak disruptions” 


    PPPL

    July 15, 2014
    John Greenwald

    Some 35 physicists from around the world gathered at PPPL last week for the second annual Laboratory-led workshop on improving ways to predict and mitigate disruptions in tokamaks. Avoiding or mitigating such disruptions, which occur when heat or electric current are suddenly reduced during fusion experiments, will be crucial for ITER the international experiment under construction in France to demonstrate the feasibility of fusion power.

    two
    Amitava Bhattacharjee, left, and John Mandrekas, a program manager in the U.S. Department of Energy’s office of Fusion Energy Sciences.(Photo by Elle Starkman/Princeton Office of
    Communications )

    PPPL Tokamak
    Tokamak at PPPL

    Presentations at the three-day session, titled “Theory and Simulation of Disruptions Workshop,” focused on the development of models that can be validated by experiment. “This is a really urgent task for ITER,” said Amitava Bhattacharjee, who heads the PPPL Theory Department and organized the workshop. The United States is responsible for designing disruption-mitigation systems for ITER, he noted, and faces a deadline of 2017.

    Speakers at the workshop included theorists and experimentalists from the ITER Organization, PPPL, General Atomics and several U.S. Universities, and from fusion facilities in the United Kingdom, China, Italy and India. Topics ranged from coping with the currents and forces that strike tokamak walls to suppressing runaway electrons that can be unleashed during experiments.

    Bringing together theorists and experimentalists is essential for developing solutions to disruptions, Bhattacharjee said. “I already see that major fusion facilities in the United States, as well as international tokamaks, are embarking on experiments that are ideal validation tools for theory and simulation,” he said. “And it is very important that theory and simulation ideas that can be validated with experimental results are presented and discussed in detail in focused workshops such as this one.”

    See the full article here.

    Princeton Plasma Physics Laboratory is a U.S. Department of Energy national laboratory managed by Princeton University.


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  • richardmitnick 8:42 am on July 14, 2014 Permalink | Reply
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    From M.I.T.: “Getting a charge out of water droplets” 


    M.I.T.

    July 14, 2014
    David L. Chandler

    Last year, MIT researchers discovered that when water droplets spontaneously jump away from superhydrophobic surfaces during condensation, they can gain electric charge in the process. Now, the same team has demonstrated that this process can generate small amounts of electricity that might be used to power electronic devices.

    instr
    The experimental chamber setup is seen from the front, with high speed camera looking into the chamber from the left.
    Photo: Nenad Miljkovic and Daniel J. Preston

    drops
    Images from a field emission scanning electron microscope show (left) an oxidized copper-oxide surface and (right) a copper-oxide surface with a 30 nanometer-thick hydrophobic coating. The inset images show a water droplet on the surface: At left, the droplet spreads out to wet the uncoated surface; at right, the droplet beads up on the hydrophobic surface, making very little contact. Photo: Nenad Miljkovic and Daniel J. Preston

    The new findings, by postdoc Nenad Miljkovic, associate professor of mechanical engineering Evelyn Wang, and two others, are published in the journal Applied Physics Letters.

    This approach could lead to devices to charge cellphones or other electronics using just the humidity in the air. As a side benefit, the system could also produce clean water.

    The device itself could be simple, Miljkovic says, consisting of a series of interleaved flat metal plates. Although his initial tests involved copper plates, he says any conductive metal would do, including cheaper aluminum.

    In initial testing, the amount of power produced was vanishingly small — just 15 picowatts, or trillionths of a watt, per square centimeter of metal plate. But Miljkovic says the process could easily be tuned to achieve at least 1 microwatt, or millionth of a watt, per square centimeter. Such output would be comparable to that of other systems that have been proposed for harvesting waste heat, vibrations, or other sources of ambient energy, and represents an amount that could be sufficient to provide useful power for electronic devices in some remote locations.

    For example, Miljkovic has calculated that at 1 microwatt per square centimeter, a cube measuring about 50 centimeters on a side — about the size of a typical camping cooler — could be sufficient to fully charge a cellphone in about 12 hours. While that may seem slow, he says, people in remote areas may have few alternatives.

    gif
    False-color time-lapse images captured via high-speed imaging show a droplet jumping (colored green) from a superhydrophobic copper oxide fin to a hydrophilic (water-attracting) copper fin (colored orange). (Courtesy of Nenad Miljkovic and Daniel J. Preston)

    There are some constraints: Because the process relies on condensation, it requires a humid environment, as well as a source of temperatures colder than the surrounding air, such as a cave or river.

    The system is based on Miljkovic and Wang’s 2013 finding — in attempting to develop an improved heat-transfer surface to be used as a condenser in applications such as power plants — that droplets on a superhydrophobic surface convert surface energy to kinetic energy as they merge to form larger droplets. This sometimes causes the droplets to spontaneously jump away, enhancing heat transfer by 30 percent relative to other techniques. They later found that in that process, the jumping droplets gain a small electric charge — meaning that the jumping, and the accompanying transfer of heat, could be enhanced by a nearby metal plate whose opposite charge is attractive to the droplets.

    Now the researchers have shown that the same process can be used to generate power, simply by giving the second plate a hydrophilic surface. As the droplets jump, they carry charge from one plate to the other; if the two plates are connected through an external circuit, that charge difference can be harnessed to provide power.

    In a practical device, two arrays of metal plates, like fins on a radiator, would be interleaved, so that they are very close but not touching. The system would operate passively, with no moving parts.

    For powering remote, automated environmental sensors, even a tiny amount of energy might be sufficient; any location where dew forms would be capable of producing power for a few hours in the morning, Miljkovic says. “Water will condense out from the atmosphere, it happens naturally,” he says.

    “The atmosphere is a huge source of power, and all you need is a temperature difference between the air and the device,” he adds — allowing the device to produce condensation, just as water condenses from warm, humid air on the outside of a cold glass.

    Chuanhua Duan, an assistant professor of mechanical engineering at Boston University who was not involved in this research, says, “This work provides a new approach for energy-harvesting, which can be used to power [microelectromechanical] devices and small electronic devices.” He adds, “Getting power from a condensation process is definitely a novel idea, as condensation is mainly used for thermal management. … Recent studies of condensation on superhydrophobic surfaces [have] extended its applications in self-cleaning and anti-icing, but no one has correlated condensation with energy-harvesting before.”

    The research, which also included MIT graduate student Daniel Preston and former postdoc Ryan Enright, now at Lucent Ireland Ltd., was supported by MIT’s Solid-State Solar-Thermal Energy Conversion Center (S3TEC), funded by the U.S. Department of Energy; the Office of Naval Research; and the National Science Foundation.

    See the full article here.


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  • richardmitnick 8:25 pm on July 13, 2014 Permalink | Reply
    Tags: , , , Clean Energy Project, Energy,   

    Clean Energy Project Hello everybody We’ve been overdue… 

    Clean Energy

    Clean Energy Project

    Hello everybody,

    We’ve been overdue for another progress report on the Clean Energy Project for some time, so here it finally comes. We hope you’ll enjoy this summary of the things that have happened since our last full report in April.

    Let’s start with the news on the CEP team again: Last time we reported that Alan was promoted to Full Professor and Sule got a job as an Assistant Professor in Ankara (Turkey). In the meantime, Johannes also landed an Assistant Professorship in the Department of Chemical and Biological Engineering at the University at Buffalo, The State University of New York, with an affiliation to the New York State Center of Excellence in Materials Informatics.
    http://www.cbe.buffalo.edu/people/full_time/j_hachmann.php

    Johannes will, however, stay involved in the Clean Energy Project and has already recruited students at Buffalo who will strengthen the CEP research efforts. Laszlo is gearing up to go out into the world as well and he will start graduate school next summer.
    http://aspuru.chem.harvard.edu/laszlo-seress/

    To compensate these losses, Ed Pyzer-Knapp from the Day Group at the University of Cambridge (UK) will join the CEP team in January 2014.
    http://www-day.ch.cam.ac.uk/epk.html

    Prof. Carlos Amador-Bedolla from UNAM in Mexico, who was active in the project a few years ago, has also started to be more active again.
    http://www.quimica.unam.mx/ficha_investigador.php?ID=77&tipo=2

    Continuity is always a big concern in a large-scale project such as the CEP, but we hope that we’ll manage the transition without too much trouble. Having the additional project branch in Buffalo will hopefully put our work on a broader foundation in the long run.

    Our work in the CEP was again recognized, e.g., by winning the 2013 Computerworld Data+ Award and the RSC Scholarship Award for Scientific Excellence of the ACS Division of Chemical Information for Johannes. CEP work has been presented on many conferences, webcasts, seminars, and talks over the last half year. It is by now a fairly well known effort in the materials science community and it has taken its place amongst the other big virtual screening projects such as the Materials Project, the Computational Materials Repository, and AFLOWLIB.

    Now to the progress on the research front: After a number of the other WCG projects have concluded, the CEP has seen a dramatic increase in computing time and returned results since the spring. These days we average between 24 and 28 y/d (that’s an increase of about 50% to our previous averages) and we have passed the mark of 21,000 years of harvested CPU time. By now we have performed over 200 million density functional theory calculations on over 3 million compounds, accumulating well over half a petabyte of data. We are currently in the process of expanding our storage capacity towards the 1PB mark by building Jabba 7 and 8. Thanks again to HGST for their generous sponsorship and Harvard FAS Research Computing for their support.

    Over the summer we have finally released the CEPDB on our new platform http://www.molecularspace.org. The launch made quite a splash. We received a lot of positive feedback in the news and from the community, and it was also nicely synchronized with the two year anniversary of the Materials Genome Initiative. We used the CEPDB release to also launched our new project webpage.

    Our latest research results and data analysis was published in “Energy and Environmental Science” and you can read all the details in this paper.

    There is still a lot of exciting research waiting to be done, and we are looking forward to tackling all this work together with you. Thanks so much for all your generous support, hard work, and enthusiasm – you guys and gals are the best! CEP would not be possible without you. CRUNCH ON!

    Best wishes from

    Your Harvard Clean Energy Project team

    The Harvard Clean Energy Project Database contains data and analyses on 2.3 million candidate compounds for organic photovoltaics. It is an open resource designed to give researchers in the field of organic electronics access to promising leads for new material developments.

    Would you like to help find new compounds for organic solar cells? By participating in the Harvard Clean Energy Project you can donate idle computer time on your PC for the discovery and design of new materials. Visit WorldCommunityGrid to get the BOINC software on which the project runs.

    CleanEnergyProjectPartners


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  • richardmitnick 7:43 am on July 12, 2014 Permalink | Reply
    Tags: , , Energy, ,   

    From NERSC: “Hot Plasma Partial to Bootstrap Current” 

    NERSC Logo
    NERSC

    July 9, 2014
    Kathy Kincade, +1 510 495 2124, kkincade@lbl.gov

    Supercomputers at NERSC are helping plasma physicists “bootstrap” a potentially more affordable and sustainable fusion reaction. If successful, fusion reactors could provide almost limitless clean energy.

    In a fusion reaction, energy is released when two hydrogen isotopes are fused together to form a heavier nucleus, helium. To achieve high enough reaction rates to make fusion a useful energy source, hydrogen contained inside the reactor core must be heated to extremely high temperatures—more than 100 million degrees Celsius—which transforms it into hot plasma. Another key requirement of this process is magnetic confinement, the use of strong magnetic fields to keep the plasma from touching the vessel walls (and cooling) and compressing the plasma to fuse the isotopes.

    react
    A calculation of the self-generated plasma current in the W7-X reactor, performed using the SFINCS code on Edison. The colors represent the amount of electric current along the magnetic field, and the black lines show magnetic field lines. Image: Matt Landreman

    So there’s a lot going on inside the plasma as it heats up, not all of it good. Driven by electric and magnetic forces, charged particles swirl around and collide into one another, and the central temperature and density are constantly evolving. In addition, plasma instabilities disrupt the reactor’s ability to produce sustainable energy by increasing the rate of heat loss.

    Fortunately, research has shown that other, more beneficial forces are also at play within the plasma. For example, if the pressure of the plasma varies across the radius of the vessel, a self-generated current will spontaneously arise within the plasma—a phenomenon known as the “bootstrap” current.

    Now an international team of researchers has used NERSC supercomputers to further study the bootstrap current, which could help reduce or eliminate the need for an external current driver and pave the way to a more cost-effective fusion reactor. Matt Landreman, research associate at the University of Maryland’s Institute for Research in Electronics and Applied Physics, collaborated with two research groups to develop and run new codes at NERSC that more accurately calculate this self-generated current. Their findings appear in Plasma Physics and Controlled Fusion and Physics of Plasmas.

    “The codes in these two papers are looking at the average plasma flow and average rate at which particles escape from the confinement, and it turns out that plasma in a curved magnetic field will generate some average electric current on its own,” Landreman said. “Even if you aren’t trying to drive a current, if you take the hydrogen and heat it up and confine it in a curved magnetic field, it creates this current that turns out to be very important. If we ever want to make a tokamak fusion plant down the road, for economic reasons the plasma will have to supply a lot of its own current.”

    One of the unique things about plasmas is that there is often a complicated interaction between where particles are in space and their velocity, Landreman added.

    “To understand some of their interesting and complex behaviors, we have to solve an equation that takes into account both the position and the velocity of the particle,” he said. “That is the core of what these computations are designed to do.”

    Evolving Plasma Behavior

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    Interior of the Alcator C-Mod tokamak at the Massachusetts Institute of Technology’s Plasma Science and Fusion Center. Image: Mike Garrett

    The Plasma Physics and Controlled Fusion paper focuses on plasma behavior in tokamak reactors using PERFECT, a code Landreman wrote. Tokamak reactors, first introduced in the 1950s, are today considered by many to be the best candidate for producing controlled thermonuclear fusion power. A tokamak features a torus (doughnut-shaped) vessel and a combination of external magnets and a current driven in the plasma required to create a stable confinement system.

    In particular, PERFECT was designed to examine the plasma edge, a region of the tokamak where “lots of interesting things happen,” Landreman said. Before PERFECT, other codes were used to predict the flows and bootstrap current in the central plasma and solve equations that assume the gradients of density and temperature are gradual.

    “The problem with the plasma edge is that the gradients are very strong, so these previous codes are not necessarily valid in the edge, where we must solve a more complicated equation,” he said. “PERFECT was built to solve such an equation.”

    For example, in most of the inner part of the tokamak there is a fairly gradual gradient of the density and temperature. “But at the edge there is a fairly big jump in density and temperature—what people call the edge pedestal. What is different about PERFECT is that we are trying to account for some of this very strong radial variation,” Landreman explained.

    These findings are important because researchers are concerned that the bootstrap current may affect edge stability. PERFECT is also used to calculate plasma flow, which also may affect edge stability.

    “My co-authors had previously done some analytic calculations to predict how the plasma flow and heat flux would change in the pedestal region compared to places where radial gradients aren’t as strong,” Landreman said. “We used PERFECT to test these calculations with a brute force numerical calculation at NERSC and found that they agreed really well. The analytic calculations provide insight into how the plasma flow and heat flux will be affected by these strong radial gradients.”

    From Tokamak to Stellarator

    In the Physics of Plasmas study, the researchers used a second code, SFINCS, to focus on related calculations in a different kind of confinement concept: a stellarator. In a stellarator the magnetic field is not axisymmetric, meaning that it looks different as you circle around the donut hole. As Landreman put it, “A tokamak is to a stellarator as a standard donut is to a cruller.”

    hxt
    HSX stellarator

    First introduced in the 1950s, stellarators have played a central role in the German and Japanese fusion programs and were popular in the U.S. until the 1970s when many fusion scientists began favoring the tokamak design. In recent years several new stellarators have appeared, including the Wendelstein 7-X (W7-X) in Germany, the Helically Symmetric Experiment in the U.S. and the Large Helical Device in Japan. Two of Landreman’s coauthors on the Physics of Plasmas paper are physicists from the Max Planck Institute for Plasma Physics, where W7-X is being constructed.

    “In the W7-X design, the amount of plasma current has a strong effect on where the heat is exhausted to the wall,” Landreman explained. “So at Max Planck they are very concerned about exactly how much self-generated current there will be when they turn on their machine. Based on a prediction for this current, a set of components called the ‘divertor’ was located inside the vacuum vessel to accept the large heat exhaust. But if the plasma makes more current than expected, the heat will come out in a different location, and you don’t want to be surprised.”

    Their concerns stemmed from the fact that the previous code was developed when computers were too slow to solve the “real” 4D equation, he added.

    “The previous code made an approximation that you could basically ignore all the dynamics in one of the dimensions (particle speed), thereby reducing 4D to 3D,” Landreman said. “Now that computers are faster, we can test how good this approximation was. And what we found was that basically the old code was pretty darn accurate and that the predictions made for this bootstrap current are about right.”

    The calculations for both studies were run on Hopper and Edison using some additional NERSC resources, Landreman noted.

    “I really like running on NERSC systems because if you have a problem, you ask a consultant and they get back to you quickly,” Landreman said. “Also knowing that all the software is up to date and it works. I’ve been using NX lately to speed up the graphics. It’s great because you can plot results quickly without having to download any data files to your local computer.”

    See the full article here.

    The National Energy Research Scientific Computing Center (NERSC) is the primary scientific computing facility for the Office of Science in the U.S. Department of Energy. As one of the largest facilities in the world devoted to providing computational resources and expertise for basic scientific research, NERSC is a world leader in accelerating scientific discovery through computation. NERSC is a division of the Lawrence Berkeley National Laboratory, located in Berkeley, California. NERSC itself is located at the UC Oakland Scientific Facility in Oakland, California.

    More than 5,000 scientists use NERSC to perform basic scientific research across a wide range of disciplines, including climate modeling, research into new materials, simulations of the early universe, analysis of data from high energy physics experiments, investigations of protein structure, and a host of other scientific endeavors.

    The NERSC Hopper system, a Cray XE6 with a peak theoretical performance of 1.29 Petaflop/s. To highlight its mission, powering scientific discovery, NERSC names its systems for distinguished scientists. Grace Hopper was a pioneer in the field of software development and programming languages and the creator of the first compiler. Throughout her career she was a champion for increasing the usability of computers understanding that their power and reach would be limited unless they were made to be more user friendly.

    gh
    (Historical photo of Grace Hopper courtesy of the Hagley Museum & Library, PC20100423_201. Design: Caitlin Youngquist/LBNL Photo: Roy Kaltschmidt/LBNL)

    NERSC is known as one of the best-run scientific computing facilities in the world. It provides some of the largest computing and storage systems available anywhere, but what distinguishes the center is its success in creating an environment that makes these resources effective for scientific research. NERSC systems are reliable and secure, and provide a state-of-the-art scientific development environment with the tools needed by the diverse community of NERSC users. NERSC offers scientists intellectual services that empower them to be more effective researchers. For example, many of our consultants are themselves domain scientists in areas such as material sciences, physics, chemistry and astronomy, well-equipped to help researchers apply computational resources to specialized science problems.


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  • richardmitnick 1:38 pm on July 10, 2014 Permalink | Reply
    Tags: , Energy, , , ,   

    From MIT: “Harnessing the speed of light” 


    MIT News

    July 8, 2014
    Steve Calechman

    The fields of data communication, fabrication, and ultrasound imaging share a common challenge when it comes to improving speed and efficiency: light’s diffraction limit. Nicholas Fang thinks his group at MIT might have found a solution.

    nf
    Nicholas Fang (Photo: David Sella)

    “In my group we play tricks with optics,” says Fang, an associate professor of mechanical engineering. These tricks have led to findings that allow for generating three-dimensional microstructures, using graphene as a more efficient delivery channel, and creating a new lens that would produce intense ultrasonic energy. With the ability to focus and target light onto the nanoscale, not only would data communication become quicker, but the diagnosis and treatment of disease would also become more precise, less invasive, less cumbersome, and more cost effective than current approaches.

    graphene
    Graphene is an atomic-scale honeycomb lattice made of carbon atoms.

    Narrowing the target

    One of Fang’s key discoveries is finding how to beat the diffraction of light. Since light and sound waves tend to spread out when blocked by an obstacle, images and communication signals can become blurry and muddled. In his lab, Fang discovered that by breaking the diffraction barrier, light signals can be sent at 10 times greater capacity. This has allowed him to produce results on the sub-nanometer scale, with light as a machining tool providing “a new degree of precision,” he says.

    The benefits are two-fold: First, such technology could allow for printing electronic circuits using more manageable and less expensive equipment. Currently, to produce nanoscale features on computing chips, an extreme UV light source is needed. The investment costs can be in the hundreds of millions of dollars, Fang says. With new, high-resolution optics that can print nanoscale elements on the wafer scale, he says, costs can decrease to hundreds of thousands of dollars.

    Second, the technology also provides the means to print and generate biosensors and scaffolding for tissue growth for artificial livers and artificial tumor models, among other things. When it comes to drug therapy, screening would become faster and delivery more precise, Fang says. The eventual goal, he says, is the creation of nanorobots and nanodevices that would can flow into the blood stream to detect malicious cells at an early stage and create a long-term, self-sustained care system.

    A smarter optical fabric for chips

    Fang says that he’s particularly excited about the potential to control and deliver a large bundle of light signals for communication over a small area. Increasing the downloading speed of data is nothing new — and is happening continually. But the ramifications of Fang’s work reach beyond downloading videos on a smartphone in under 30 seconds. The improvement means the same amount of data can be handled and exchanged across different chips, he says.

    “Our vision is the cell phone will eventually be replaced by wearable devices,” says Fang, noting Pebble and Google Glass as current examples. This will help create a better user experience, through providing a more visual life that’s more transparent, portable, and energy efficient, he says.

    The hope could lie in transmitting light on chips with graphene. Light itself is a marvelous carrier of information, Fang says, because it’s not limited by bandwidth, and signals don’t necessarily interfere with each other. The only problem is that the diffraction limit creates a bottleneck in which close signals can start bending towards each other. Think of a highway with everyone trying to exit at the same place at the same time. To prevent this kind of jamming with information, each signal needs to maintain its own identity.

    This is where graphene comes in. The electronic benefits of the carbon-based material are already known, but the optical properties remain untapped. Graphene is 10 times faster optically than electronically and can guide light precisely, keeping signals in their own channel, in a sense, making light signals look more like motorcycles (smaller) rather than a big vans in traffic, Fang says. With light signals having a reduced size, more signals can be driven in the same field. “We could use graphene as our information highway,” he says.

    One big question that remains is how much power is needed to drive each bit. But potential applications include implementation in Intel or IBM chips, increasing the amount of data capacity while decreasing the amount of response time to information. The end product? A smarter chip, Fang says.

    Seeing cells through the body

    For another project, Fang is applying his knowledge of optics to acoustics and ultrasound. Being able to generate intense ultrasonic energy would break up specific cells or cell membranes and inject them with drug particles. The challenge, once again, is the diffraction limit. Available medical devices can operate down to half a millimeter, but individual cells are micrometers. The need is to overcome 10 times the lens change in order to treat or cure one particular cell.

    Fang says his research holds this possibility: He’s shown the ability to generate a flat lens that can deliver acoustic energy into a tightly focused spot, meaning a healthy cell could be differentiated from a malignant one, and therapy could be targeted. A physician collaborator is still needed to build a suitable test that would gain eventual FDA approval, but Fang says he is excited about the potential. Compared to current methods, the device would be more precise — a large fiber bundle wouldn’t be needed to penetrate the body’s tissue — and would only need a fraction of the power. “We do consider this medical ultrasound innovation could be less invasive and it could be less painful for the patients,” he says.

    See the full article here.


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