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  • richardmitnick 1:23 pm on September 23, 2018 Permalink | Reply
    Tags: , Clean Energy, , , New battery gobbles up carbon dioxide,   

    From MIT News: “New battery gobbles up carbon dioxide” 

    MIT News
    MIT Widget

    From MIT News

    September 21, 2018
    David L. Chandler

    1
    This scanning electron microscope image shows the carbon cathode of a carbon-dioxide-based battery made by MIT researchers, after the battery was discharged. It shows the buildup of carbon compounds on the surface, composed of carbonate material that could be derived from power plant emissions, compared to the original pristine surface (inset). Courtesy of the researchers

    Scanning transmission electron microscope Wikipedia

    Lithium-based battery could make use of greenhouse gas before it ever gets into the atmosphere.

    A new type of battery developed by researchers at MIT could be made partly from carbon dioxide captured from power plants. Rather than attempting to convert carbon dioxide to specialized chemicals using metal catalysts, which is currently highly challenging, this battery could continuously convert carbon dioxide into a solid mineral carbonate as it discharges.

    While still based on early-stage research and far from commercial deployment, the new battery formulation could open up new avenues for tailoring electrochemical carbon dioxide conversion reactions, which may ultimately help reduce the emission of the greenhouse gas to the atmosphere.

    The battery is made from lithium metal, carbon, and an electrolyte that the researchers designed. The findings are described today in the journal Joule, in a paper by assistant professor of mechanical engineering Betar Gallant, doctoral student Aliza Khurram, and postdoc Mingfu He.

    Currently, power plants equipped with carbon capture systems generally use up to 30 percent of the electricity they generate just to power the capture, release, and storage of carbon dioxide. Anything that can reduce the cost of that capture process, or that can result in an end product that has value, could significantly change the economics of such systems, the researchers say.

    However, “carbon dioxide is not very reactive,” Gallant explains, so “trying to find new reaction pathways is important.” Generally, the only way to get carbon dioxide to exhibit significant activity under electrochemical conditions is with large energy inputs in the form of high voltages, which can be an expensive and inefficient process. Ideally, the gas would undergo reactions that produce something worthwhile, such as a useful chemical or a fuel. However, efforts at electrochemical conversion, usually conducted in water, remain hindered by high energy inputs and poor selectivity of the chemicals produced.

    Gallant and her co-workers, whose expertise has to do with nonaqueous (not water-based) electrochemical reactions such as those that underlie lithium-based batteries, looked into whether carbon-dioxide-capture chemistry could be put to use to make carbon-dioxide-loaded electrolytes — one of the three essential parts of a battery — where the captured gas could then be used during the discharge of the battery to provide a power output.

    This approach is different from releasing the carbon dioxide back to the gas phase for long-term storage, as is now used in carbon capture and sequestration, or CCS. That field generally looks at ways of capturing carbon dioxide from a power plant through a chemical absorption process and then either storing it in underground formations or chemically altering it into a fuel or a chemical feedstock.

    Instead, this team developed a new approach that could potentially be used right in the power plant waste stream to make material for one of the main components of a battery.

    While interest has grown recently in the development of lithium-carbon-dioxide batteries, which use the gas as a reactant during discharge, the low reactivity of carbon dioxide has typically required the use of metal catalysts. Not only are these expensive, but their function remains poorly understood, and reactions are difficult to control.

    By incorporating the gas in a liquid state, however, Gallant and her co-workers found a way to achieve electrochemical carbon dioxide conversion using only a carbon electrode. The key is to preactivate the carbon dioxide by incorporating it into an amine solution.

    “What we’ve shown for the first time is that this technique activates the carbon dioxide for more facile electrochemistry,” Gallant says. “These two chemistries — aqueous amines and nonaqueous battery electrolytes — are not normally used together, but we found that their combination imparts new and interesting behaviors that can increase the discharge voltage and allow for sustained conversion of carbon dioxide.”

    They showed through a series of experiments that this approach does work, and can produce a lithium-carbon dioxide battery with voltage and capacity that are competitive with that of state-of-the-art lithium-gas batteries. Moreover, the amine acts as a molecular promoter that is not consumed in the reaction.

    The key was developing the right electrolyte system, Khurram explains. In this initial proof-of-concept study, they decided to use a nonaqueous electrolyte because it would limit the available reaction pathways and therefore make it easier to characterize the reaction and determine its viability. The amine material they chose is currently used for CCS applications, but had not previously been applied to batteries.

    This early system has not yet been optimized and will require further development, the researchers say. For one thing, the cycle life of the battery is limited to 10 charge-discharge cycles, so more research is needed to improve rechargeability and prevent degradation of the cell components. “Lithium-carbon dioxide batteries are years away” as a viable product, Gallant says, as this research covers just one of several needed advances to make them practical.

    But the concept offers great potential, according to Gallant. Carbon capture is widely considered essential to meeting worldwide goals for reducing greenhouse gas emissions, but there are not yet proven, long-term ways of disposing of or using all the resulting carbon dioxide. Underground geological disposal is still the leading contender, but this approach remains somewhat unproven and may be limited in how much it can accommodate. It also requires extra energy for drilling and pumping.

    The researchers are also investigating the possibility of developing a continuous-operation version of the process, which would use a steady stream of carbon dioxide under pressure with the amine material, rather than a preloaded supply the material, thus allowing it to deliver a steady power output as long as the battery is supplied with carbon dioxide. Ultimately, they hope to make this into an integrated system that will carry out both the capture of carbon dioxide from a power plant’s emissions stream, and its conversion into an electrochemical material that could then be used in batteries. “It’s one way to sequester it as a useful product,” Gallant says.

    “It was interesting that Gallant and co-workers cleverly combined the prior knowledge from two different areas, metal-gas battery electrochemistry and carbon-dioxide capture chemistry, and succeeded in increasing both the energy density of the battery and the efficiency of the carbon-dioxide capture,” says Kisuk Kang, a professor at Seoul National University in South Korea, who was not associated with this research.

    “Even though more precise understanding of the product formation from carbon dioxide may be needed in the future, this kind of interdisciplinary approach is very exciting and often offers unexpected results, as the authors elegantly demonstrated here,” Kang adds.

    See the full article here .


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    Please help promote STEM in your local schools.


    Stem Education Coalition

    MIT Seal

    The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

    MIT Campus

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  • richardmitnick 8:21 am on September 8, 2018 Permalink | Reply
    Tags: , , , , , Clean Energy, , Hydrogenase is an enzyme present in algae that is capable of reducing protons into hydrogen, Natural photosynthesis, Photosystem II, Scientists pioneer a new way to turn sunlight into fuel, Solar energy conversion, St. Johns College at Cambridge,   

    From University of Cambridge: “Scientists pioneer a new way to turn sunlight into fuel” 

    U Cambridge bloc

    From University of Cambridge

    03 Sep 2018
    No writer credit

    The quest to find new ways to harness solar power has taken a step forward after researchers successfully split water into hydrogen and oxygen by altering the photosynthetic machinery in plants.

    1
    Experimental two-electrode setup showing the photoelectrochemical cell illuminated with simulated solar light. Credit: Katarzyna Sokół

    Photosynthesis is the process plants use to convert sunlight into energy. Oxygen is produced as a by-product of photosynthesis when the water absorbed by plants is ‘split’. It is one of the most important reactions on the planet because it is the source of nearly all of the world’s oxygen. Hydrogen which is produced when the water is split could potentially be a green and unlimited source of renewable energy.

    A new study led by academics at the University of Cambridge, used semi-artificial photosynthesis to explore new ways to produce and store solar energy. They used natural sunlight to convert water into hydrogen and oxygen using a mixture of biological components and manmade technologies.

    The research could now be used to revolutionise the systems used for renewable energy production. A new paper, published in [Nature Energy], outlines how academics at the Reisner Laboratory in Cambridge’s Department of Chemistry developed their platform to achieve unassisted solar-driven water-splitting.

    Their method also managed to absorb more solar light than natural photosynthesis.

    Katarzyna Sokół, first author and PhD student at St John’s College, said: “Natural photosynthesis is not efficient because it has evolved merely to survive so it makes the bare minimum amount of energy needed – around 1-2 per cent of what it could potentially convert and store.”

    Artificial photosynthesis has been around for decades but it has not yet been successfully used to create renewable energy because it relies on the use of catalysts, which are often expensive and toxic. This means it can’t yet be used to scale up findings to an industrial level.

    The Cambridge research is part of the emerging field of semi-artificial photosynthesis which aims to overcome the limitations of fully artificial photosynthesis by using enzymes to create the desired reaction.

    Sokół and the team of researchers not only improved on the amount of energy produced and stored, they managed to reactivate a process in the algae that has been dormant for millennia.

    She explained: “Hydrogenase is an enzyme present in algae that is capable of reducing protons into hydrogen. During evolution, this process has been deactivated because it wasn’t necessary for survival but we successfully managed to bypass the inactivity to achieve the reaction we wanted – splitting water into hydrogen and oxygen.”

    Sokół hopes the findings will enable new innovative model systems for solar energy conversion to be developed.

    She added: “It’s exciting that we can selectively choose the processes we want, and achieve the reaction we want which is inaccessible in nature. This could be a great platform for developing solar technologies. The approach could be used to couple other reactions together to see what can be done, learn from these reactions and then build synthetic, more robust pieces of solar energy technology.”

    This model is the first to successfully use hydrogenase and photosystem II to create semi-artificial photosynthesis driven purely by solar power.

    Dr Erwin Reisner, Head of the Reisner Laboratory, a Fellow of St John’s College, University of Cambridge, and one of the paper’s authors described the research as a ‘milestone’.

    He explained: “This work overcomes many difficult challenges associated with the integration of biological and organic components into inorganic materials for the assembly of semi-artificial devices and opens up a toolbox for developing future systems for solar energy conversion.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Cambridge Campus

    The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

     
  • richardmitnick 8:31 am on September 5, 2018 Permalink | Reply
    Tags: , Clean Energy, , Tandem solar cell design,   

    From UCLA Newsroom: “Dual-layer solar cell developed at UCLA sets record for efficiently generating power” 


    From UCLA Newsroom

    August 30, 2018
    Matthew Chin

    1
    A solar cell developed by UCLA Engineering researchers converts 22.4 percent of incoming energy from the sun, a record for this type of cell. Oszie Tarula/UCLA

    Materials scientists from the UCLA Samueli School of Engineering have developed a highly efficient thin-film solar cell that generates more energy from sunlight than typical solar panels, thanks to its double-layer design.

    The device is made by spraying a thin layer of perovskite — an inexpensive compound of lead and iodine that has been shown to be very efficient at capturing energy from sunlight — onto a commercially available solar cell. The solar cell that forms the bottom layer of the device is made of a compound of copper, indium, gallium and selenide, or CIGS.

    The team’s new cell converts 22.4 percent of the incoming energy from the sun, a record in power conversion efficiency for a perovskite–CIGS tandem solar cell. The performance was confirmed in independent tests at the U.S. Department of Energy’s National Renewable Energy Laboratory. (The previous record, set in 2015 by a group at IBM’s Thomas J. Watson Research Center, was 10.9 percent.) The UCLA device’s efficiency rate is similar to that of the poly-silicon solar cells that currently dominate the photovoltaics market.

    The research, which was published today in Science, was led by Yang Yang, UCLA’s Carol and Lawrence E. Tannas Jr. Professor of Materials Science.

    2
    Qifeng Han, Yang Yang and Lei Meng. Oszie Tarula/UCLA

    “With our tandem solar cell design, we’re drawing energy from two distinct parts of the solar spectrum over the same device area,” Yang said. “This increases the amount of energy generated from sunlight compared to the CIGS layer alone.”

    Yang added that the technique of spraying on a layer of perovskite could be easily and inexpensively incorporated into existing solar-cell manufacturing processes.

    The cell’s CIGS base layer, which is about 2 microns (or two-thousandths of a millimeter) thick, absorbs sunlight and generates energy at a rate of 18.7 percent efficiency on its own, but adding the 1 micron-thick perovskite layer improves its efficiency — much like how adding a turbocharger to a car engine can improve its performance. The two layers are joined by a nanoscale interface that the UCLA researchers designed; the interface helps give the device higher voltage, which increases the amount of power it can export.

    And the entire assembly sits on a glass substrate that’s about 2 millimeters thick.

    “Our technology boosted the existing CIGS solar cell performance by nearly 20 percent from its original performance,” Yang said. “That means a 20 percent reduction in energy costs.”

    He added that devices using the two-layer design could eventually approach 30 percent power conversion efficiency. That will be the research group’s next goal.

    The study’s lead authors are Qifeng Han, a visiting research associate in Yang’s laboratory, and Yao-Tsung Hsieh and Lei Meng, who both recently earned their doctorates at UCLA. The study’s other authors are members of Yang’s research group and researchers from Solar Frontier Corp.’s Atsugi Research Center in Japan.

    The research was supported by the National Science Foundation and the Air Force Office of Scientific Research. Yang and his research group have been working on tandem solar cells for several years and their accomplishments include developing transparent tandem solar cells that could be used in windows.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    UC LA Campus

    For nearly 100 years, UCLA has been a pioneer, persevering through impossibility, turning the futile into the attainable.

    We doubt the critics, reject the status quo and see opportunity in dissatisfaction. Our campus, faculty and students are driven by optimism. It is not naïve; it is essential. And it has fueled every accomplishment, allowing us to redefine what’s possible, time after time.

    This can-do perspective has brought us 12 Nobel Prizes, 12 Rhodes Scholarships, more NCAA titles than any university and more Olympic medals than most nations. Our faculty and alumni helped create the Internet and pioneered reverse osmosis. And more than 100 companies have been created based on technology developed at UCLA.

     
  • richardmitnick 3:53 am on August 24, 2018 Permalink | Reply
    Tags: Clean Energy, , ,   

    From CSIROscope: “How hydrogen power can help us cut emissions, boost exports, and even drive further between refills” 

    CSIRO bloc

    From CSIROscope

    24 August 2018
    Sam Bruce

    1
    Could this be the way to fill up in future?

    Hydrogen could become a significant part of Australia’s energy landscape within the coming decade, competing with both natural gas and batteries, according to our new roadmap for the industry.

    2

    Hydrogen gas is a versatile energy carrier with a wide range of potential uses. However, hydrogen is not freely available in the atmosphere as a gas. It therefore requires an energy input and a series of technologies to produce, store and then use it.

    Why would we bother? Because hydrogen has several advantages over other energy carriers, such as batteries. It is a single product that can service multiple markets and, if produced using low- or zero-emissions energy sources, it can help us significantly cut greenhouse emissions.

    2
    Potential uses for hydrogen. No image credit.

    Compared with batteries, hydrogen can release more energy per unit of mass. This means that in contrast to electric battery-powered cars, it can allow passenger vehicles to cover longer distances without refuelling. Refuelling is quicker too and is likely to stay that way.

    The benefits are potentially even greater for heavy vehicles such as buses and trucks which already carry heavy payloads, and where lengthy battery recharge times can affect the business model.

    Hydrogen can also play an important role in energy storage, which will be increasingly necessary both in remote operations such as mine sites, and as part of the electricity grid to help smooth out the contribution of renewables such as wind and solar. This could work by using the excess renewable energy (when generation is high and/or demand is low) to drive hydrogen production via electrolysis of water. The hydrogen can then be stored as compressed gas and put into a fuel cell to generate electricity when needed.

    Australia is heavily reliant on imported liquid fuels and does not currently have enough liquid fuel held in reserve. Moving towards hydrogen fuel could potentially alleviate this problem. Hydrogen can also be used to produce industrial chemicals such as ammonia and methanol, and is an important ingredient in petroleum refining.

    Further, as hydrogen burns without greenhouse emissions, it is one of the few viable green alternatives to natural gas for generating heat.

    Our roadmap predicts that the global market for hydrogen will grow in the coming decades. Among the prospective buyers of Australian hydrogen would be Japan, which is comparatively constrained in its ability to generate energy locally. Australia’s extensive natural resources, namely solar, wind, fossil fuels and available land lend favourably to the establishment of hydrogen export supply chains.

    Why embrace hydrogen now?

    Given its widespread use and benefit, interest in the “hydrogen economy” has peaked and troughed for the past few decades. Why might it be different this time around? While the main motivation is hydrogen’s ability to deliver low-carbon energy, there are a couple of other factors that distinguish today’s situation from previous years.

    Our analysis shows that the hydrogen value chain is now underpinned by a series of mature technologies that are technically ready but not yet commercially viable. This means that the narrative around hydrogen has now shifted from one of technology development to “market activation”.

    The solar panel industry provides a recent precedent for this kind of burgeoning energy industry. Large-scale solar farms are now generating attractive returns on investment, without any assistance from government. One of the main factors that enabled solar power to reach this tipping point was the increase in production economies of scale, particularly in China. Notably, China has recently emerged as a proponent for hydrogen, earmarking its use in both transport and distributed electricity generation.

    But whereas solar power could feed into a market with ready-made infrastructure (the electricity grid), the case is less straightforward for hydrogen. The technologies to help produce and distribute hydrogen will need to develop in concert with the applications themselves.

    A roadmap for hydrogen

    In light of this, the primary objective of our National Hydrogen Roadmap is to provide a blueprint for the development of a hydrogen industry in Australia. With several activities already underway, it is designed to help industry, government and researchers decide where exactly to focus their attention and investment.

    Our first step was to calculate the price points at which hydrogen can compete commercially with other technologies. We then worked backwards along the value chain to understand the key areas of investment needed for hydrogen to achieve competitiveness in each of the identified potential markets. Following this, we modelled the cumulative impact of the investment priorities that would be feasible in or around 2025.

    3

    What became evident from the report was that the opportunity for clean hydrogen to compete favourably on a cost basis with existing industrial feedstocks and energy carriers in local applications such as transport and remote area power systems is within reach. On the upstream side, some of the most material drivers of reductions in cost include the availability of cheap low emissions electricity, utilisation and size of the asset.

    The development of an export industry, meanwhile, is a potential game-changer for hydrogen and the broader energy sector. While this industry is not expected to scale up until closer to 2030, this will enable the localisation of supply chains, industrialisation and even automation of technology manufacture that will contribute to significant reductions in asset capital costs. It will also enable the development of fossil-fuel-derived hydrogen with carbon capture and storage, and place downward pressure on renewable energy costs dedicated to large scale hydrogen production via electrolysis.

    In light of global trends in industry, energy and transport, development of a hydrogen industry in Australia represents a real opportunity to create new growth areas in our economy. Blessed with unparalleled resources, a skilled workforce and established manufacturing base, Australia is extremely well placed to capitalise on this opportunity. But it won’t eventuate on its own.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    SKA/ASKAP radio telescope at the Murchison Radio-astronomy Observatory (MRO) in Mid West region of Western Australia

    So what can we expect these new radio projects to discover? We have no idea, but history tells us that they are almost certain to deliver some major surprises.

    Making these new discoveries may not be so simple. Gone are the days when astronomers could just notice something odd as they browse their tables and graphs.

    Nowadays, astronomers are more likely to be distilling their answers from carefully-posed queries to databases containing petabytes of data. Human brains are just not up to the job of making unexpected discoveries in these circumstances, and instead we will need to develop “learning machines” to help us discover the unexpected.

    With the right tools and careful insight, who knows what we might find.

    CSIRO campus

    CSIRO, the Commonwealth Scientific and Industrial Research Organisation, is Australia’s national science agency and one of the largest and most diverse research agencies in the world.

     
  • richardmitnick 11:04 am on June 27, 2018 Permalink | Reply
    Tags: Clean Energy, , , ,   

    From Max Planck Institute for Plasma Physics: “Wendelstein 7-X achieves world record” 

    MPIPP bloc

    From Max Planck Institute for Plasma Physics

    June 25, 2018
    Isabella Milch

    Wendelstgein 7-X stellarator, built in Greifswald, Germany

    Stellarator record for fusion product / First confirmation for optimisation

    In the past experimentation round Wendelstein 7-X achieved higher temperatures and densities of the plasma, longer pulses and the stellarator world record for the fusion product. Moreover, first confirmation for the optimisation concept on which Wendelstein 7-X is based, was obtained. Wendelstein 7-X at Max Planck Institute for Plasma Physics (IPP) in Greifswald, the world’s largest fusion device of the stellarator type, is investigating the suitability of this concept for application in power plants.

    1
    View inside the plasma vessel with graphite tile cladding. Photo: IPP, Jan Michael Hosan

    Unlike in the first experimentation phase 2015/16, the plasma vessel of Wendelstein 7-X has been fitted with interior cladding since September last year (see PI 8/2017). The vessel walls are now covered with graphite tiles, thus allowing higher temperatures and longer plasma discharges. With the so-called divertor it is also possible to control the purity and density of the plasma: The divertor tiles follow the twisted contour of the plasma edge in the form of ten broad strips along the wall of the plasma vessel. In this way, they protect particularly the wall areas onto which the particles escaping from the edge of the plasma ring are made to impinge. Along with impurities, the impinging particles are here neutralised and pumped off.

    “First experience with the new wall elements are highly positive”, states Professor Dr. Thomas Sunn Pedersen. While by the end of the first campaign pulse lengths of six seconds were being attained, plasmas lasting up to 26 seconds are now being produced. A heating energy of up to 75 megajoules could be fed into the plasma, this being 18 times as much as in the first operation phase without divertor. The heating power could also be increased, this being a prerequisite to high plasma density.

    2
    Wendelstein 7-X attained the Stellarator world record for the fusion product. This product of the ion temperature, plasma density and energy confinement time specifies how close one is getting to the reactor values needed to ignite a plasma. Graphic: IPP

    In this way a record value for the fusion product was attained. This product of the ion temperature, plasma density and energy confinement time specifies how close one is getting to the reactor values needed to ignite a plasma. At an ion temperature of about 40 million degrees and a density of 0.8 x 1020 particles per cubic metre Wendelstein 7-X has attained a fusion product affording a good 6 x 1026 degrees x second per cubic metre, the world’s stellarator record. “This is an excellent value for a device of this size, achieved, moreover, under realistic conditions, i.e. at a high temperature of the plasma ions”, says Professor Sunn Pedersen. The energy confinement time attained, this being a measure of the quality of the thermal insulation of the magnetically confined plasma, indicates with an imposing 200 milliseconds that the numerical optimisation on which Wendelstein 7-X is based might work: “This makes us optimistic for our further work.”

    The fact that optimisation is taking effect not only in respect of the thermal insulation is testified to by the now completed evaluation of experimental data from the first experimentation phase from December 2015 to March 2016, which has just been reported in Nature Physics (see below). This shows that also the bootstrap current behaves as expected. This electric current is induced by pressure differences in the plasma and could distort the tailored magnetic field. Particles from the plasma edge would then no longer impinge on the right area of the divertor. The bootstrap current in stellarators should therefore be kept as low as possible. Analysis has now confirmed that this has actually been accomplished in the optimised field geometry. “Thus, already during the first experimentation phase important aspects of the optimisation could be verified”, states first author Dr. Andreas Dinklage. “More exact and systematic evaluation will ensue in further experiments at much higher heating power and higher plasma pressure.”

    Since the end of 2017 Wendelstein 7-X has undergone further extensions: These include new measuring equipment and heating systems. Plasma experiments are to be resumed in July. Major extension is planned as of autumn 2018: The present graphite tiles of the divertor are to be replaced by carbon-reinforced carbon components that are additionally water-cooled. They are to make discharges lasting up to 30 minutes possible, during which it can be checked whether Wendelstein 7-X permanently meets its optimisation objectives as well.

    Background

    The objective of fusion research is to develop a power plant favourable to the climate and environment. Like the sun, it is to derive energy from fusion of atomic nuclei. Because the fusion fire needs temperatures exceeding 100 million degrees to ignite, the fuel, viz. a low-density hydrogen plasma, ought not to come into contact with cold vessel walls. Confined by magnetic fields, it is suspended inside a vacuum chamber with almost no contact.

    The magnetic cage of Wendelstein 7-X is produced by a ring of 50 superconducting magnet coils about 3.5 metres high. Their special shapes are the result of elaborate optimisation calculations. Although Wendelstein 7-X will not produce energy, it hopes to prove that stellarators are suitable for application in power plants.

    Its aim is to achieve for the first time in a stellarator the quality of confinement afforded by competing devices of the tokamak type. In particular, the device is to demonstrate the essential advantage of stellarators, viz. their capability to operate in continuous mode.

    Science paper:
    Magnetic configuration effects on the Wendelstein 7-X stellarator. Nature Physics

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition

    MPIPP campus

    The Max Planck Institute of Plasma Physics (Max-Planck-Institut für Plasmaphysik, IPP) is a physics institute for the investigation of plasma physics, with the aim of working towards fusion power. The institute also works on surface physics, also with focus on problems of fusion power.

    The IPP is an institute of the Max Planck Society, part of the European Atomic Energy Community, and an associated member of the Helmholtz Association.

    The IPP has two sites: Garching near Munich (founded 1960) and Greifswald (founded 1994), both in Germany.

    It owns several large devices, namely

    the experimental tokamak ASDEX Upgrade (in operation since 1991)
    the experimental stellarator Wendelstein 7-AS (in operation until 2002)
    the experimental stellarator Wendelstein 7-X (awaiting licensing)
    a tandem accelerator

    It also cooperates with the ITER and JET projects.

     
  • richardmitnick 10:44 am on June 12, 2018 Permalink | Reply
    Tags: Clean Energy, , Revolutionizing geothermal energy research,   

    From Sanford Underground Research Facility: “Revolutionizing geothermal energy research” 

    SURF logo
    Sanford Underground levels

    From Sanford Underground Research Facility

    June 11, 2018
    Constance Walter

    The SIMFIP tool is changing the way researchers measure and design hydro fractures.

    1
    Deep underground on the 4850 Level at Sanford Lab, engineer Paul Cook explains how the SIMFIP tool will be used to measure openings in hard rock. Matthew Kapust

    On May 22, researchers with the SIGMA-V experiment worked in near silence in the West Drift on the 4850 Level. The locomotives sat quietly on the tracks, jack-leg drills rested against drift walls and operations ceased for several minutes at a time as the team began pumping pressurized water into the injection well, one of eight boreholes drilled for this experiment.

    “We requested quiet because we use sensitive seismic monitoring equipment,” said Tim Kneafsey, earth scientist at Lawrence Berkeley National Laboratory (LBNL). “The signals we measure are very small and we don’t want vibrations from other sources overwhelming those signals.”

    Kneafsey is the principal investigator for the Enhanced Geothermal Systems (EGS) Collab Project, a collaboration comprised of eight national laboratories and six universities who are working to improve geothermal technologies. The test featured the SIMFIP (Step-Rate Injection Method for Fracture In-Situ Properties), a tool that revolutionizes the way scientists can study geothermal energy, a process that pulls heat from the earth as it extracts steam or hot water, which is then converted to electricity.

    Developed at LBNL, the SIMFIP allows precise measurements of displacements in the rock and, most importantly, the aperture, or opening, of a hydro fracture.

    The extreme quiet paid off, Kneafsey said.

    “Our goal was to create a fracture from a specific zone in our injection well that would connect to our production well—about 10 meters away. And we were successful in doing that,” Kneafsy said.

    “People were excited when the connection between the boreholes was made and measured. But it took a while for the team to realize how far we had come and how much research, logistics, planning and collaboration went into that moment. It was gratifying to say the least, and there was certainly a sense of accomplishment.” —Hunter Knox

    The experiment

    Before the introduction of the SIMFIP, separate tools were used to create and measure hydro fractures. They work like this: “Straddle packers”—pipes with two deflated balloons on either end—are placed inside boreholes. Once inside, the balloons are inflated and water injected down the pipes to create an airtight section. They continue to pump water until the rock fractures, then remove the packers and insert the measuring tool. In the time it takes to do all that, much of the pertinent data is lost, leaving traces, but little else.

    “Even if you did get the aperture, when you released the pressure, the hydro fracture was already closing,” said Yves Guglielmi, a geologist at LBNL who designed the tool. “You don’t have the ‘true’ aperture and you also don’t know how the aperture might vary during the test.”

    With the introduction of the SIMFIP, a small device that sits between the two packers, they can the aperture in real-time.

    “This is really a new way to do the work,” Guglielmi said. “It will help us understand the whole process of initiating and growing hydro fractures in hard rock, which is kind of new. This is fundamental science. If we understand how hydro fractures will behave in this kind of rock, we can begin to make intelligent, complex fractures that can capture more heat from the earth.”

    The device is “bristling with sensors and other instrumentation that give us a close-up view of what happens when the rock is stimulated—all in real-time,” said Paul Cook, LBNL engineer.

    The SIMFIP measures fracture openings in hard rock in the EGS Collab test site. The team had drilled eight slightly downward-sloping boreholes in the rib (side) of the West Drift: The injection hole, used for stimulating the rock, and production well, which produces the fluid, run parallel to each other through the rock. Six other boreholes contain equipment to monitor microseismic activity (rock displacement); electrical resistivity tomography (subsurface imaging); temperature; and strain (how rocks move when stimulated).

    Nestled between the straddle packers in the injection hole, the SIMFIP measured the rock opening as the team looked on.

    The SIMFIP difference

    The SIGMA-V team hoped to see signals as small as a few microns of displacements in the rock. As they watched data accumulate in real time over a two-day period, the excitement in the West Drift was palpable.

    “People were excited when the connection between the boreholes was made and measured,” said Hunter Knox, the field coordinator with Sandia National Laboratory, “But it took a while for the team to realize how far we had come and how much research, logistics, planning and collaboration went into that moment. It was gratifying to say the least, and there was certainly a sense of accomplishment.”

    Measurements from the SIMFIP could remove barriers that stand in the way of commercializing geothermal systems, which have the potential to provide enough energy to power 100 million American homes.

    “We know fracturing rock can be done. But can it be effective for geothermal purposes? We need good, well-monitored field tests of fracturing, particularly in crystalline rock, to better understand that,” Kneafsey said.

    With the first test under its belt, the EGS Collab just moved a step closer to that goal.

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    No image credit or caption

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    About us.
    The Sanford Underground Research Facility in Lead, South Dakota, advances our understanding of the universe by providing laboratory space deep underground, where sensitive physics experiments can be shielded from cosmic radiation. Researchers at the Sanford Lab explore some of the most challenging questions facing 21st century physics, such as the origin of matter, the nature of dark matter and the properties of neutrinos. The facility also hosts experiments in other disciplines—including geology, biology and engineering.

    The Sanford Lab is located at the former Homestake gold mine, which was a physics landmark long before being converted into a dedicated science facility. Nuclear chemist Ray Davis earned a share of the Nobel Prize for Physics in 2002 for a solar neutrino experiment he installed 4,850 feet underground in the mine.

    Homestake closed in 2003, but the company donated the property to South Dakota in 2006 for use as an underground laboratory. That same year, philanthropist T. Denny Sanford donated $70 million to the project. The South Dakota Legislature also created the South Dakota Science and Technology Authority to operate the lab. The state Legislature has committed more than $40 million in state funds to the project, and South Dakota also obtained a $10 million Community Development Block Grant to help rehabilitate the facility.

    In 2007, after the National Science Foundation named Homestake as the preferred site for a proposed national Deep Underground Science and Engineering Laboratory (DUSEL), the South Dakota Science and Technology Authority (SDSTA) began reopening the former gold mine.

    In December 2010, the National Science Board decided not to fund further design of DUSEL. However, in 2011 the Department of Energy, through the Lawrence Berkeley National Laboratory, agreed to support ongoing science operations at Sanford Lab, while investigating how to use the underground research facility for other longer-term experiments. The SDSTA, which owns Sanford Lab, continues to operate the facility under that agreement with Berkeley Lab.

    The first two major physics experiments at the Sanford Lab are 4,850 feet underground in an area called the Davis Campus, named for the late Ray Davis. The Large Underground Xenon (LUX) experiment is housed in the same cavern excavated for Ray Davis’s experiment in the 1960s.
    LUX/Dark matter experiment at SURFLUX/Dark matter experiment at SURF

    In October 2013, after an initial run of 80 days, LUX was determined to be the most sensitive detector yet to search for dark matter—a mysterious, yet-to-be-detected substance thought to be the most prevalent matter in the universe. The Majorana Demonstrator experiment, also on the 4850 Level, is searching for a rare phenomenon called “neutrinoless double-beta decay” that could reveal whether subatomic particles called neutrinos can be their own antiparticle. Detection of neutrinoless double-beta decay could help determine why matter prevailed over antimatter. The Majorana Demonstrator experiment is adjacent to the original Davis cavern.

    Another major experiment, the Long Baseline Neutrino Experiment (LBNE)—a collaboration with Fermi National Accelerator Laboratory (Fermilab) and Sanford Lab, is in the preliminary design stages. The project got a major boost last year when Congress approved and the president signed an Omnibus Appropriations bill that will fund LBNE operations through FY 2014. Called the “next frontier of particle physics,” LBNE will follow neutrinos as they travel 800 miles through the earth, from FermiLab in Batavia, Ill., to Sanford Lab.

    Fermilab LBNE
    LBNE

     
  • richardmitnick 1:12 pm on March 11, 2018 Permalink | Reply
    Tags: , Clean Energy, , Eni, ,   

    From MIT: “A new era in fusion research at MIT” 

    MIT News

    MIT Widget

    MIT News

    March 9, 2018
    Francesca McCaffrey | MIT Energy Initiative

    MIT Energy Initiative founding member Eni announces support for key research through MIT Laboratory for Innovation in Fusion Technologies.

    1

    A new chapter is beginning for fusion energy research at MIT.

    This week the Italian energy company Eni, a founding member of the MIT Energy Initiative (MITEI), announced it has reached an agreement with MIT to fund fusion research projects run out of the MIT Plasma Science and Fusion Center (PSFC)’s newly created Laboratory for Innovation in Fusion Technologies (LIFT). The expected investment in these research projects will amount to about $2 million over the following years.

    This is part of a broader engagement with fusion research and the Institute as a whole: Eni also announced a commitment of $50 million to a new private company with roots at MIT, Commonwealth Fusion Systems (CFS), which aims to make affordable, scalable fusion power a reality.

    “This support of LIFT is a continuation of Eni’s commitment to meeting growing global energy demand while tackling the challenge of climate change through its research portfolio at MIT,” says Robert C. Armstrong, MITEI’s director and the Chevron Professor of Chemical Engineering at MIT. “Fusion is unique in that it is a zero-carbon, dispatchable, baseload technology, with a limitless supply of fuel, no risk of runaway reaction, and no generation of long-term waste. It also produces thermal energy, so it can be used for heat as well as power.”

    Still, there is much more to do along the way to perfecting the design and economics of compact fusion power plants. Eni will fund research projects at LIFT that are a continuation of this research and focus on fusion-specific solutions. “We are thrilled at PSFC to have these projects funded by Eni, who has made a clear commitment to developing fusion energy,” says Dennis Whyte, the director of PSFC and the Hitachi America Professor of Engineering at MIT. “LIFT will focus on cutting-edge technology advancements for fusion, and will significantly engage our MIT students who are so adept at innovation.”

    Tackling fusion’s challenges

    The inside of a fusion device is an extreme environment. The creation of fusion energy requires the smashing together of light elements, such as hydrogen, to form heavier elements such as helium, a process that releases immense amounts of energy. The temperature at which this process takes place is too hot for solid materials, necessitating the use of magnets to hold the hot plasma in place.

    One of the projects PSFC and Eni intend to carry out will study the effects of high magnetic fields on molten salt fluid dynamics. One of the key elements of the fusion pilot plant currently being studied at LIFT is the liquid immersion blanket, essentially a flowing pool of molten salt that completely surrounds the fusion energy core. The purpose of this blanket is threefold: to convert the kinetic energy of fusion neutrons to heat for eventual electricity production; to produce tritium — a main component of the fusion fuel; and to prevent the neutrons from reaching other parts of the machine and causing material damage.

    It’s critical for researchers to be able to predict how the molten salt in such an immersion blanket would move when subjected to high magnetic fields such as those found within a fusion plant. As such, the researchers and their respective teams plan to study the effects of these magnetohydrodynamic forces on the salt’s fluid dynamics.

    A history of innovation

    During the 23 years MIT’s Alcator C-Mod tokamak fusion experiment was in operation, it repeatedly advanced records for plasma pressure in a magnetic confinement device. Its compact, high-magnetic-field fusion design confined superheated plasma in a small donut-shaped chamber.

    “The key to this success was the innovations pursued more than 20 years ago at PSFC in developing copper magnets that could access fields well in excess of other fusion experiments. The coupling between innovative technology development and advancing fusion science is in the DNA of the Plasma Science and Fusion Center,” says PSFC Deputy Director Martin Greenwald.

    In its final run in 2016, Alcator C-Mod set a new world record for plasma pressure, the key ingredient to producing net energy from fusion. Since then, PSFC researchers have used data from these decades of C-Mod experiments to continue to advance fusion research. Just last year, they used C-Mod data to create a new method of heating fusion plasmas in tokamaks which could result in the heating of ions to energies an order of magnitude greater than previously reached.

    A commitment to low-carbon energy

    MITEI’s mission is to advance low-carbon and no-carbon emissions solutions to efficiently meet growing global energy needs. Critical to this mission are collaborations between academia, industry, and government — connections MITEI helps to develop in its role as MIT’s hub for multidisciplinary energy research, education, and outreach.

    Eni is an inaugural, founding member of the MIT Energy Initiative, and it was through their engagement with MITEI that they became aware of the fusion technology commercialization being pursued by CFS and its immense potential for revolutionizing the energy system. It was through these discussions, as well, that Eni investors learned of the high-potential fusion research projects taking place through LIFT at MIT, spurring them to support the future of fusion at the Institute itself.

    Eni CEO Claudio Descalzi said, “Today is a very important day for us. Thanks to this agreement, Eni takes a significant step forward toward the development of alternative energy sources with an ever lower environmental impact. Fusion is the true energy source of the future, as it is completely sustainable, does not release emissions or waste, and is potentially inexhaustible. It is a goal that we are determined to reach quickly.” He added, “We are pleased and excited to pursue such a challenging goal with a collaborator like MIT, with unparalleled experience in the field and a long-standing and fruitful alliance with Eni.”

    These fusion projects are the latest in a line of MIT-Eni collaborations on low- and no-carbon energy projects. One of the earliest of these was the Eni-MIT Solar Frontiers Center, established in 2010 at MIT. Through its mission to develop competitive solar technologies, the center’s research has yielded the thinnest, lightest solar cells ever produced, effectively able to turn any surface, from fabric to paper, into a functioning solar cell. The researchers at the center have also developed new, luminescent materials that could allow windows to efficiently collect solar power.

    Other fruits of MIT-Eni collaborations include research into carbon capture systems to be installed in cars, wearable technologies to improve workplace safety, energy storage, and the conversion of carbon dioxide into fuel.

    See the full article here .

    Please help promote STEM in your local schools.

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    MIT Seal

    The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

    MIT Campus

     
  • richardmitnick 12:59 pm on March 9, 2018 Permalink | Reply
    Tags: , Clean Energy, , Gasification, , Turning landfill into energy   

    From Horizon: “Turning landfill into energy” 

    1

    Horizon

    07 March 2018
    Jon Cartwright

    1
    Advanced gasification methods can turn any waste except metal and rubble into fuel for electricity. Credit – Pixabay/ Prylarer

    Landfill is both ugly and polluting. But a new breed of technology promises to make it a thing of the past, transforming a huge portion of landfill material into clean gas.

    It’s thanks to a process called gasification, which involves turning carbon-based materials into gas by heating them to a high temperature but without burning them. The gas can be stored until it is needed for the generation of electricity.

    According to its developers, advanced gasification can be fed by plastic, biomass, textiles – just about anything except metal and rubble. Out of the other end comes syngas – a clean, easily combustible gas made up of carbon monoxide and hydrogen.

    The basics of the technology are old. Back in the 19th century, gasification plants existed in many of Europe’s major cities, turning coal into coal gas for heating and lighting.

    Gasification waned after the discovery of natural gas reserves early last century. Then in the past 20 years or so, it had a small renaissance, as gasification plants sprung up to process waste wood.

    In a new, advanced implementation, however, a much broader range of materials can be processed, and the output gas is much cleaner. ‘Gasification is clearly gaining a lot of traction, but we’ve taken it further,’ said Jean-Eric Petit of French company CHO Power, based in Bordeaux.

    Gasification

    Gasification involves heating without combustion. At temperatures greater than 700°C, a lot of hydrocarbon-based materials break down into a gas of carbon monoxide and hydrogen – syngas – which can be used as a fuel.

    For materials such as wood, this is relatively straightforward. Try it with other hydrocarbon materials, and especially hard-to-recycle industrial waste, however, and the reaction tends to generate pollutants, such as tar.

    But tar itself is just a more complex hydrocarbon. That is why Petit and his colleagues have developed a higher temperature process, at some 1200°C, in which even tar is broken down.

    The result is syngas, which, unline other thermal processes, does not create dangerous pollutants. In fact, it is high-quality enough to be fed directly into high-efficiency gas engines, generating electricity with twice the efficiency of the steam turbines used with conventional gasification, says Petit.

    CHO Power has already built an advanced gasification plant in Morcenx, France, which converts 55,000 tonnes of wood, biomass and industrial waste a year into 11 megawatts of electricity.

    In December the EU announced that the company will receive a €30 million loan from the European Investment Bank to construct another plant in the Thouarsais area of France.

    The company is not the first to attempt advanced gasification on a commercial scale. But, said Petit: ‘We think we’re the first to crack it.’

    CHO Power’s gasification plants still need to have waste delivered to them. Hysytech, a company in Torino, Italy, however, plans to bring gasification to industry’s door.

    The idea is to build a small gasification plant, processing at least 100 kilos per hour of waste, next to any industrial plant that deals with hydrocarbon materials – a textiles or plastics manufacturer, for instance.

    Then, any waste the industrial plant generates can be turned straight into syngas for electricity generation on site, avoiding the emissions associated with transporting waste to a distant gasification plant.

    2
    The gas produced by CHO Power’s gasification process is refined at 1,200°C in their turboplasma facility (left) so that it can be used in a gas engine (right) to generate electricity. Credit – CHO Power

    Small-scale

    The problem is that, historically, gasification on this scale has cost too much to be in an industry’s interests. But Hysytech believes it has made small-scale gasification cost effective, by developing a novel reactor known as a fluidised bed.

    When waste materials are fed into this reactor, a fluid is passed through them to create an even temperature and to allow the gas to leave easily. If the materials need a lot of time to turn to gas, they remain in the reactor until they are gasified, but the fluid can be sped up if the materials turn to gas quickly.

    The result, for smaller plants at least, is a more efficient and cost-effective process. ‘Our system is designed and built to operate year-round with a good efficiency, easy operation and little maintenance,’ said Andrés Saldivia, Hysytech’s head of business development.

    Hysytech has built a pilot plant that has about one-tenth the envisaged output, processing 10 kilos of waste an hour into syngas. Currently, its engineers are constructing a full-sized demo plant that will include an additional power-to-gas system, to link the gasification to surplus energy from wind turbines and solar panels so the energy is not wasted.

    With this additional system, the surplus energy is used to split water into hydrogen and oxygen. Using a carbon source, this hydrogen is then converted into methane, which can be used like everyday natural gas.

    ‘Our goal is to have it ready for the market (by) 2019,’ said Saldivia.

    See the full article here .

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  • richardmitnick 10:05 pm on March 8, 2018 Permalink | Reply
    Tags: , , , , , , , , Clean Energy, , , International Women's Day, , , , , ,   

    From PI: Women in STEM-“Celebrating International Women’s Day” 

    4

    Is it not a shame that we need to have a special day to celebrate women when they are so already fantastic and exceptionally brilliant in the physical sciences?

    Check out this blog post-
    https://sciencesprings.wordpress.com/2018/03/08/from-the-conversation-women-in-stem-perish-not-publish-new-study-quantifies-the-lack-of-female-authors-in-scientific-journals/

    “”I have done a couple of STEM events, but there have never been this many girls. There are so many here. It is really empowering. Go girls in STEM!” Eama, Grade 12

    Today’s Inspiring Future Women in Science conference was a success. Mona Nemar, Canada’s Chief Science Advisor, gave opening remarks encouraging the students in attendance to take advantage of the opportunity to learn from the speakers to come.

    2
    “The days of women being held back or being excluded from science are over. Now, more than ever women are entering, remaining in, and revolutionizing the science fields. Today is a shining example of that.”
    -Mona Nemar, Chief Science Advisor, Government of Canada

    Mona, read my above post on women getting not published.

    The speakers and panelists, who included a chemist, engineer, astronomer, ecologist, and surgeon, talked about the challenges and triumphs that a career in STEM brings. Students were then treated to a speed mentoring session where they were able to ask questions and interact with women from a broad number of STEM careers. Read more about how this conference is inspiring young women here.

    3
    “This conference showed me there are so many things you can do going into [a career in STEM], so now I feel more inspired, and I feel more confident and not scared to go into science.” Lealan, Age 16

    Programs like Perimeter’s “Inspiring Future Women in Science” conference are helping young women see their own potential and reach out for careers in STEM. And more talented female scientists today, means a brighter future tomorrow.

    Thank you for being part of the equation.
    4

     
  • richardmitnick 3:07 pm on February 13, 2018 Permalink | Reply
    Tags: , , Clean Energy, Lead-free perovskite material for solar cells   

    From Brown: “Researchers discover new lead-free perovskite material for solar cells” 

    Brown University
    Brown University

    February 13, 2018
    Kevin Stacey
    kevin_stacey@brown.edu
    401-863-3766

    1
    Getting the lead out
    Researchers have shown that titanium is an attractive choice to replace the toxic lead in the prevailing perovskite thin film solar cells. Padture Lab / Brown University

    A class of materials called perovskites has emerged as a promising alternative to silicon for making inexpensive and efficient solar cells. But for all their promise, perovskites are not without their downsides. Most contain lead, which is highly toxic, and include organic materials that are not particularly stable when exposed to the environment.

    Now a group of researchers at Brown University and University of Nebraska – Lincoln (UNL) has come up with a new titanium-based material for making lead-free, inorganic perovskite solar cells. In a paper published in the journal Joule (a new energy-focused sister journal to Cell), the researchers show that the material can be a good candidate, especially for making tandem solar cells — arrangements in which a perovskite cells are placed on top of silicon or another established material to boost the overall efficiency.

    “Titanium is an abundant, robust and biocompatible element that, until now, has been largely overlooked in perovskite research,” said the senior author of the new paper, Nitin Padture, the Otis E. Randall University Professor in Brown’s School of Engineering and director of Institute for Molecular and Nanoscale Innovation. “We showed that it’s possible to use titanium-based material to make thin-film perovskites and that the material has favorable properties for solar applications which can be tuned.”

    Interest in perovskites, a class of materials with a particular crystalline structure, for clean energy emerged in 2009, when they were shown to be able to convert sunlight into electricity. The first perovskite solar cells had a conversion efficiency of only about 4 percent, but that has quickly skyrocketed to near 23 percent, which rivals traditional silicon cells. And perovskites offer some intriguing advantages. They’re potentially cheaper to make than silicon cells, and they can be partially transparent, enabling new technologies like windows that generate electricity.

    “One of the big thrusts in perovskite research is to get away from lead-based materials and find new materials that are non-toxic and more stable,” Padture said. “Using computer simulations, our theoretician collaborators at UNL predicted [ACS Energy Letters] that a class of perovskites with cesium, titanium and a halogen component (bromine or/and iodine) was a good candidate. The next step was to actually make a solar cell using that material and test its properties, and that’s what we’ve done here.”

    The team made semi-transparent perovskite films that had bandgap — a measure of the energy level of photons the material can absorb — of 1.8 electron volts, which is considered to be ideal for tandem solar applications. The material had a conversion efficiency of 3.3 percent, which is well below that of lead-based cells, but a good start for an all-new material, the researchers say.

    “There’s a lot of engineering you can do to improve efficiency,” Yuanyuan Zhou, an assistant professor (research) of engineering at Brown and a study co-author. “We think this material has a lot of room to improve.”

    Min Chen, a Ph.D. student of materials science at Brown and the first author of the paper, used a high-temperature evaporation method to prepare the films, but says the team is investigating alternative methods. “We are also looking for new low-temperature and solvent-based methods to reduce the potential cost of cell fabrication,” he said.

    The research showed the material has several advantages over other lead-free perovskite alternatives. One contender for a lead-free perovskite is a material made largely from tin, which rusts easily when exposed to the environment. Titanium, on the hand, is rust-resistant. The titanium-perovskite also has an open-circuit voltage — a measure of the total voltage available from a solar cell — of over one volt. Other lead-free perovskites generally produce voltage smaller than 0.6 volts.

    “Open-circuit voltage is a key property that we can use to evaluate the potential of a solar cell material,” Padture said. “So, having such a high value at the outset is very promising.”

    The researchers say that material’s relatively large bandgap compared to silicon makes it a prime candidate to serve as the top layer in a tandem solar cell. The titanium-perovskite upper layer would absorb the higher-energy photons from the sun that the lower silicon layer can’t absorb because of its smaller bandgap. Meanwhile, lower energy photons would pass through the semi-transparent upper layer to be absorbed by the silicon, thereby increasing the cell’s total absorption capacity.

    “Tandem cells are the low-hanging fruit when it comes to perovskites,” Padture said. “We’re not looking to replace existing silicon technology just yet, but instead we’re looking to boost it. So if you can make a lead-free tandem cell that’s stable, then that’s a winner. This new material looks like a good candidate.”

    Other co-authors on the paper were Ming-Gang Ju, Alexander Carl, Yingxia Zong, Ronald Grimm, Jiajun Gu and Xiao Cheng Zeng. The research was supported by the National Science Foundation (OIA-1538893, DMR-1420645).

    See the full article here .

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    Welcome to Brown

    Brown U Robinson Hall
    Located in historic Providence, Rhode Island and founded in 1764, Brown University is the seventh-oldest college in the United States. Brown is an independent, coeducational Ivy League institution comprising undergraduate and graduate programs, plus the Alpert Medical School, School of Public Health, School of Engineering, and the School of Professional Studies.

    With its talented and motivated student body and accomplished faculty, Brown is a leading research university that maintains a particular commitment to exceptional undergraduate instruction.

    Brown’s vibrant, diverse community consists of 6,000 undergraduates, 2,000 graduate students, 400 medical school students, more than 5,000 summer, visiting and online students, and nearly 700 faculty members. Brown students come from all 50 states and more than 100 countries.

    Undergraduates pursue bachelor’s degrees in more than 70 concentrations, ranging from Egyptology to cognitive neuroscience. Anything’s possible at Brown—the university’s commitment to undergraduate freedom means students must take responsibility as architects of their courses of study.

     
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