Science and Technology

Discussion in 'The Mainboard' started by angus, Feb 5, 2016.

  1. angus

    angus Well-Known Member
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    Writing the future of rewritable memory
    July 23, 2018, University of Alberta
    [​IMG]
    To demonstrate the new discovery, Achal, Wolkow, and their fellow scientists not only fabricated the world's smallest maple leaf, they also encoded the entire alphabet at a density of 138 terabytes, roughly equivalent to writing 350,000 letters across a grain of rice. For a playful twist, Achal also encoded music as an atom-sized song, the first 24 notes of which will make any video-game player of the 80s and 90s nostalgic for yesteryear but excited for the future of technology and society. Credit: Roshan Achal, Nature Communications

    Scientists at the University of Alberta in Edmonton, Canada have created the most dense, solid-state memory in history that could soon exceed the capabilities of current hard drives by 1,000 times.

    Faced with the question of how to respond to the ever-increasing needs of our data-driven society, the answer for a team of scientists was simple: more memory, less space. Finding the way to do that, however, was anything but simple, involving years of painstaking incremental advances in atomic-scale nanotechnology.

    But their new discovery for atomic-scale rewritable memory—quickly removing or replacing single atoms—allows the creation of small, stable, dense memory at the atomic-scale.

    "Essentially, you can take all 45 million songs on iTunes and store them on the surface of one quarter,"
    said Roshan Achal, Ph.D. student in Department of Physics at the University of Alberta and lead author on the new research. "Five years ago, this wasn't even something we thought possible."

    Previous discoveries were stable only at cryogenic conditions, meaning this new finding puts society light years closer to meeting the need for more storage for the current and continued deluge of data. One of the most exciting features of this memory is that it's road-ready for real-world temperatures, as it can withstand normal use and transportation beyond the lab.

    "What is often overlooked in the nanofabrication business is actual transportation to an end user, that simply was not possible until now given temperature restrictions," continued Achal. "Our memory is stable well above room temperature and precise down to the atom."

    Achal explained that immediate applications will be data archival. Next steps will be increasing readout and writing speeds, meaning even more flexible applications.

    More memory, less space

    Achal works with University of Alberta physics professor Robert Wolkow, a pioneer in the field of atomic-scale physics. Wolkow perfected the art of the science behind nanotip technology, which, thanks to Wolkow and his team's continued work, has now reached a tipping point, meaning scaling up atomic-scale manufacturing for commercialization.

    "With this last piece of the puzzle now in-hand, atom-scale fabrication will become a commercial reality in the very near future," said Wolkow. Wolkow's Spin-off company, Quantum Silicon Inc., is hard at work on commercializing atom-scale fabrication for use in all areas of the technology sector.

    To demonstrate the new discovery, Achal, Wolkow, and their fellow scientists not only fabricated the world's smallest maple leaf, they also encoded the entire alphabet at a density of 138 terabytes, roughly equivalent to writing 350,000 letters across a grain of rice. For a playful twist, Achal also encoded music as an atom-sized song, the first 24 notes of which will make any video-game player of the 80s and 90s nostalgic for yesteryear but excited for the future of technology and society.




    Read more at: https://phys.org/news/2018-07-future-rewritable-memory.html#jCp
     
  2. WhiskeyDelta

    WhiskeyDelta Well-Known Member
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    I remember when getting like a megabyte of memory was a big freaking deal. Now you can get terabytes of storage for under a hundred bucks.

    I got old.
     
  3. Mr Bulldops

    Mr Bulldops If you’re juiceless, you’re useless
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    My first computer had a 4gb hard drive. I got it for a HS graduation present so I could use it in college. I thought there was no way I would ever fill that up. Then Napster happened
     
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  4. NP13

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    i upgraded the pc i got in HS from 32 to 64MB of memory. also put in a 40GB HD
     
  5. angus

    angus Well-Known Member
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    Proof of concept.

    Lab unveils the world's first rollable touch-screen tablet, inspired by ancient scrolls

    August 31, 2018 in Technology / Consumer & Gadgets
    [​IMG]
    An ipad that fits your pocket: introducing a roll-up tablet with flexible screen real estate. Credit: Queen's University
    A Queen's University research team has taken a page from history, rolled it up and created the MagicScroll – a rollable touch-screen tablet designed to capture the seamless flexible screen real estate of ancient scrolls in a modern-day device. Led by bendable-screen pioneer Dr. Roel Vertegaal, this new technology is set to push the boundaries of flexible device technology into brand new territory.

    The device is comprised of a high-resolution, 7.5" 2K resolution flexible display that can be rolled or unrolled around a central, 3-D-printed cylindrical body containing the device's computerized inner-workings. Two rotary wheels at either end of the cylinder allow the user to scroll through information on the touch screen. When a user narrows in on an interesting piece of content that they would like to examine more deeply, the display can be unrolled and function as a tablet display. Its light weight and cylindrical body makes it much easier to hold with one hand than an iPad. When rolled up, it fits your pocket and can be used as a phone, dictation device or pointing device.

    "We were inspired by the design of ancient scrolls because their form allows for a more natural, uninterrupted experience of long visual timelines," says Dr. Vertegaal, Professor of Human-Computer Interaction and Director of the Queen's University Human Media Lab. Another source of inspiration was the old rolodex filing systems that were used to store and browse contact cards. The MagicScroll's scroll wheel allows for infinite scroll action for quick browsing through long lists. Unfolding the scroll is a tangible experience that gives a full screen view of the selected item. Picture browsing through your Instagram timeline, messages or LinkedIn contacts this way."



    Beyond the innovative flexible display, the prototype also features a camera that allows users to employ the rolled-up MagicScroll as a gesture-based control device – similar to that of Nintendo's 'Wiimote'. And the device's rotary wheels contain robotic actuators that allow the device to physically move or spin in place in various scenarios, like when it receives a notification for instance.

    "Eventually, our hope is to design the device so that it can even roll into something as small as a pen that you could carry in your shirt pocket," says Dr. Vertegaal. "More broadly, the MagicScroll project is also allowing us to further examine notions that screens don't have to be flat, and 'anything can become a screen.' Whether it's a reusable cup made of an interactive screen on which you can select your order before arriving at a coffee-filling kiosk, or a display on your clothes, we're exploring how objects can become the apps."
     
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  6. angus

    angus Well-Known Member
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  7. angus

    angus Well-Known Member
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  8. angus

    angus Well-Known Member
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    Amazon and Google ask for non-stop data from smart home devices
    Some gadget makers are pushing back.

    Jon Fingas
    1h ago in Internet
    Nicole Lee/Engadget

    You'd expect voice assistants to collect data whenever you control a smart home device -- that's how they work. Amazon and Google have lately been asking for a continuous flow of data in the name of convenience, however, and those device makers aren't always happy. Bloomberg has learned that Logitech and other hardware
    makers (some speaking anonymously) have objected to these requests for a steady stream of information over concerns they could violate privacy. Logitech has purposefully provided generic information rather than talking about individual devices, while others have reportedly asked for privacy "concessions" and have been rejected.
    The companies say they need this information for the sake of faster response to voice commands as well as ensuing that smart displays have up to date information. It might be difficult to avoid sending at least some continuous information. However, there are concerns the constant supply of data could be used to piece together your habits -- when you leave for work, watch TV and go to bed. That's potentially valuable for marketing and customer research.

    Google declined to comment on how it uses continuous data from Assistant, but Amazon said that it doesn't use info for advertising or sell it to third parties. Amazon isn't about to pitch sleep aids because you tell Alexa to turn on the lights at 3AM. The concern is that both Amazon and Google could do this, and that users didn't consent to sharing as much smart home data as they do today.
     
  9. angus

    angus Well-Known Member
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    With a 'hello,' researchers demonstrate first fully automated DNA data storage



    https://m.phys.org/news/2019-03-fully-automated-dna-storage.html
     
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  10. Biship

    Biship Well-Known Member
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    Kansas State WildcatsKansas City RoyalsKansas City ChiefsSporting Kansas City

    Incredible
     
  11. IV

    IV Freedom is the right of all sentient beings
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    How is this simultaneously happening while parents won’t vaccinate their kids
     
  12. angus

    angus Well-Known Member
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    Idiocracy
     
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  13. Prospector

    Prospector I am not a new member
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    Raising the American Weakling
    Nautilus Visit Site
    By Tom Vanderbilt February 9, 2017
    13,605 saves
    There are two very different interpretations of our dwindling grip strength.

    [​IMG]
    When she was a practicing occupational therapist, Elizabeth Fain started noticing something odd in her clinic: Her patients were weak. More specifically, their grip strengths, recorded via a hand-held dynamometer, were “not anywhere close to the norms” that had been established back in the 1980s.
    Fain knew that physical activity levels and hand-use patterns had changed a lot since then. Jobs had become increasingly automated, the professional and service sectors had grown, all sorts of measures of physical activity (like the likelihood that a child walks to school1) had declined, and the personal computer age had dawned. But to see the numbers decline so steeply and quickly was still a surprise, and not just to her.

    [​IMG]
    Early strength: A set of experiments in the late 1800s showed that most infants are able to hang on to a suspended stick, supporting their own weight. Photo by: H. Armstrong Roberts/ClassicStock/Getty Images
    Unlike most findings in the sleepy field of occupational therapy, her findings, which were published last year in the Journal of Hand Therapy, touched off a media firestorm, as the revelation seemed to encapsulate any number of smoldering fears in one handy conflagration: The loss of human potential in the face of automation, of our increasing time spent on smartphones and other devices, the erosion of our masculine norms,2 of the fragility and general shiftlessness of millennials. Even taking into account the cautionary statistical notes—that the sample sizes of the 1980s studies were not huge, that Fain’s study was mostly college students—the idea of a loss in human strength, expressed through a statistical measure hardly anyone had previously heard of, seemed to hint at some latter-day version of degeneration.

    That message was reinforced by the sheer predictive power of grip strength. In a study published in 2015 in The Lancet, the health outcomes of nearly 140,000 people across 17 countries were tracked over four years, via a variety of measures—including grip strength.3 Grip strength was not only “inversely associated with all-cause mortality”—every 5 kilogram (kg) decrement in grip strength was associated with a 17 percent risk increase—but as the team, led by McMaster University professor of medicine Darryl Leong, noted: “Grip strength was a stronger predictor of all-cause and cardiovascular mortality than systolic blood pressure.”

    Gripping is part of a long story in which we have been getting weaker for millions of years.

    “I’ve seen people refer to it as a ‘will-to-live’ meter,” says Richard Bohannon, a professor of health studies at North Carolina’s Campbell University. Grip strength, he suggests, is not necessarily an overall indicator of health, nor is it causative—if you start building your grip strength now it does not ensure you will live longer—“but it is related to important things.” What’s more, it’s non-invasive, and inexpensive to measure. Bohannon notes that in his home-care practice, a grip strength test is now de rigueur. “I use it in basically all of my patients,” he says. “It gives you an overall sense of their status, and high grip strength is better than low grip strength.”

    The argument seemed to line up neatly. We are raising a generation of weaklings, more prone to everything from premature aging to mental disorders. Or is the opposite true? Is this just the latest step in the age-old weakening of our species as we emerged from the trees and built up civilization?

    [​IMG]
    Pulling up empty: Samuel Bennett made waves when he failed to do a single pull-up during an NHL fitness scouting test, despite being touted as the top prospect for the 2014 entry draft. Photo by: Graig Abel/NHLI via Getty Images
    Pound per pound, babies are remarkably strong. The parent learns this the first time they proffer their finger. In a famous series of experiments in the late 19th century—of the sort one can scarcely imagine today—Louis Robinson, a surgeon at a children’s hospital in England, tested some 60 infants—many within an hour of birth—by having them hang from a suspended “walking stick.” With only two exceptions, according to one report, the infants were able to hang on, sustaining “the weight of their body for at least ten seconds.”9 Many could do it for upward of a minute. In a later-published photograph, Robinson swapped out the bar for a tree branch, to bring home his whole point: Our “arboreal ancestry.”

    This idea—that we are born to brachiate (or swing through trees)—lurks behind the peculiar power of grip strength. “From an evolutionary perspective,” note the authors of a study in Evolution and Human Behavior, “it is interesting to ask why [hand-grip strength] would be such a ubiquitous measure of human health and vitality.”10 Strong hands helped keep us in the trees—in other words, alive (to this day, heavier birth weight is correlated with higher grip strength11). We came down, but then our hands adapted to new uses, the sorts of things that made us human.

    As the evolutionary biologist Mary Marzke argues, our hands today were literally shaped around millions of years of using and making tools (our cerebral hemispheres, notes John Napier, author of the classic study Hands, expanded as our tool making did). The human hand became an almost perfect gripping machine. That long opposable thumb, enabling what has been termed the “power grip” and the “precision grip,” looms most obvious. But consider also the Papillary ridges, those tougher, thicker parts of the skin, found on the human heel, but also on the human palm—a vestigial souvenir from our time as quadrupeds. Their placement, as Napier writes in Hands, “corresponds with the principal areas of gripping and weight bearing, where they serve very much the same function as the treads on an automobile tire.” Eccrine glands perfectly line the papillary ridge, Napier notes, providing a grip-enhancing “lubrication system.” This sort of “frictional adaptation” does not kick in until we are around 2, writes Frank Wilson in The Hand (before then, we just grip harder).

    Gripping, then, is a deep part of our biology and evolution as a species. It’s also part of a long story in which we have been getting weaker for millions of years, largely because of a decline in physical activity. The human skeleton, for example, is “relatively gracile” (weak) compared to hominoids.12 Those infants tested by Robinson, stout hangers-on though they may have been, can hardly compete with infant monkeys, who can hang on for upward of a half hour. Why? Because they need to. “Modern infants,” as one researcher notes, “as well as their fairly recent human antecedents, do not need to hang on with their hands and feet from the moment of birth.”13

    It’s easy to be troubled by a nearly 20 percent decrease in grip strength, especially given that it happened in one generation.

    In other words, our hands have changed as our environment has changed. Studies done in traditional societies have shown that correlations between grip strength and hunting success have declined. “Perhaps strength become becomes less of an important determinant of hunting ability,” writes one researcher, “as a population undergoes acculturation and the range of variation in skill within the population increases.”14 In a world where one can get more done with a smartphone than a hand-axe, our hands seem to be on the move, as they have always been.

    Witness, for example, the palmaris longus, the tendon that connects your forearm to your palm (and which becomes visible, in many people, when you flex your palm upward). The muscle, according to one hypothesis, was once important for tasks like brachiation, but has been slowly declining in humans. In some cultures some 63 percent of people no longer have it. As one group of researchers notes, “if human evolution continues along similar lines wherein the muscle belly [the sum of all the muscle fibers] continues to phylogenetically reduce, it is expected that this muscle will eventually not be found in humans.”15

    This inverse correlation between grip strength and civilization has been both celebrated and debated over the centuries. Jean-Jacques Rousseau saw in civilization a weakening of “all the vigor of which the human species was capable.” The French explorer François Perón, intent on discrediting Rousseau’s argument, brought an early Régnier dynamometer to Tasmania to test the strength of “savage man” against his own sailors. The more “savage” the people, Peron reported, contra Rousseau, the weaker they were. He took his grip strength tests as conclusive proof against the then-fashionable argument “that the physical degeneration of man follows the perfection of civilization.”

    [​IMG]
    Easy repair: Occupational therapist Elizabeth Fain suspects that even the grip strength of auto mechanics has weakened in recent decades, because of the advent of automatic tools. Photo by: PETER PARKS/AFP/Getty Images (left), and Andreas Rentz/Getty Images (right)
    Which is the correct interpretation of the great modern weakening? There has certainly been an across-the-board change in the usefulness of grip strength over a very short period of time, which Fain acknowledges. “An auto mechanic would have a higher grip strength than a salesman, typically,” Fain notes. But even a contemporary auto mechanic, she suspects, would have a lower grip strength than their 1985 equivalent. “A lot of their tools have changed to automate things,” she says. “To change a tire, they used to do that with mechanical force, but now they have an air gun to turn those nuts and bolts for them.” We can even now read of pro athletes unable to complete a single pull-up.16

    Coincidentally, Fain grew up on a farm, where manual labor was common. She jokes that no one ever wanted to thumb-wrestle her brother. His hands, grown strong from milking cows, were like steel pincers. I came of age in the 1980s, so I also belong to the norm group that posted the strong numbers in Fain’s comparison. But I am hardly the picture of a lumberjack. My days are mostly devoted to sitting at my keyboard, researching and writing articles like this one.

    Curious about what that all of that means for my own grip strength, I went out and bought a Jamar Hydraulic Hand Dynamometer, which is favored by clinicians. My strength rang in at nearly 62 kgs which, according to a chart of normative grip strengths in the Jamar’s manual, was above the mean for males 45-49, but not hugely outside the standard deviation. In that data, my age group did worse than the 20-24 age group, like you’d expect.

    What was surprising was that my grip strength came in at 40 percent above a group of contemporary male college students that Fain measured last year. She found that a group of males aged 20-24—ages that had produced some of the peak mean grip strength scores in the 1980s tests—had a mean grip strength of just 44.7 kgs, well below my own and far below the same cohort in the 1980s, whose mean was in the low 50s. There were also significant declines in female grip strength.

    [​IMG]
    Gen X power: Average right-hand grip strength for men and women as a function of age, as described in the Jamar Dynamometer manual. Photo by: Data from the Jamar Norms Poster
    It’s easy to be troubled by a nearly 20 percent decrease in grip strength, especially given that it happened in one generation, a blink of an eye compared to evolutionary time scales. But to denounce it as a sign of culture denigration is to try to fix culture as natural, when in reality it is as shifting as our bodies themselves. Should we decry the withering away of muscle, if our bodies prosper in the environment that surrounds them? The last 10 years have also seen a dramatic increase in myopia, most likely because we spend more time indoors and because of the type of work we do. But should we stop reading? Should we swing from the trees to get our grip strength back? Even if we got our paleo hands back, what good would they do us in the modern world?

    And if a measure like grip strength were truly so robust a health indicator, shouldn’t life spans be declining as (and if) grip strength was? Bohannon warns me, “I would not interpret small declines in grip strength as indicative of decreasing health.” As he notes, you have to get pretty low in the statistical profile—“in the lowest quartile or tertile or below the median of a tested population”—before you start to get into increased mortality risk territory.

    Another problem is to fixate (like those 19th-century explorers did) on grip strength itself as a flawless indicator of health (or anything else). After all, as the anthropologist Michael Gurven (who has measured grip strength among the Tsimane’ Amerindians of the Bolivian Amazon, among other groups) reminded me, “women have lower grip strength than men, yet live longer and have lower mortality than men at most ages.” He also advised me not to discount the motivational factor in grip strength testing: “Offering a prize to folks does increase their scores.” Perhaps I was so intent on proving that “I still had it” against my millennial counterparts that I simply tried harder.

    Despite all these caveats, there is a larger narrative into which declining grip strength fits neatly. Daniel Lieberman, Harvard University paleoanthropologist, and author of The Story of the Human Body, tells me that “overall strength and fitness are declining in the post-industrial world, and the epidemiological transition is increasing lifespan.” But, he noted, “those two trends are occurring for totally different reasons.”

    We tend to fixate on the measure of lifespan, but overlook morbidity. Here, Lieberman says, the data are unequivocal. “As we are living longer,” he says, people “are also suffering from much longer periods of chronical illness as they age.” People may be living longer, due to advances in pharmaceuticals or medical care, but as he asks, “is she/he healthy?” Health, he says, “is not just life expectancy.”

    Our weakening grips are, if nothing else, a corollary of an increasingly sick population. So, by all means, go to the gym, not to turn back the evolutionary tide, but for your own well-being. Evolution, as Lieberman reminds us in The Story of the Human Body, is just about passing your genes, not ensuring a long and healthy life. “From an evolutionary perspective, there is no such thing as optimal health.” Creating that definition is up to you.

    Tom Vanderbilt is a regular Nautilus contributor and the author of, most recently, You May Also Like: Taste in an Age of Endless Choice.

    References

    1. Mackett, R.L. Children’s travel behaviour and its health implications. Transport Policy 26, 66-72 (2013).

    2. French, D. Men Are Getting Weaker—Because We’re Not Raising Men National Review http://www.nationalreview.com (2016).

    3. Leong, D.P., et al. Prognostic value of grip strength: findings from the Prospective Urban Rural Epidemiology (PURE) study. The Lancet 386, 266-273 (2015).

    4. Syddall, H., Cooper, C., Martin, F., Briggs, R., & Aihie Sayer, A. Is grip strength a useful single marker of frailty?” Age and Ageing 32, 650-656 (2003).

    5. Cruz-Jentoft, A.J., et al. Sarcopenia: European consensus on definition and diagnosis: Report of the European working group on Sarcopenia in older people. Age and Ageing 39, 412–23 (2010).

    6. Bohannon, R.W. Muscle strength: clinical and prognostic value of hand-grip dynamometry. Current Opinion in Clinical Nutrition & Metabolic Care 18, 465-470 (2015).

    7. Mendes, J., Alves, P., & Amaral, T.F. Comparison of nutritional status assessment parameters in predicting length of hospital stay in cancer patients. Clinical Nutrition 33, 466-470 (2014).

    8. Björk, M.P., Johansson, B., & Hassing, L.B. I forgot when I lost my grip—strong associations between cognition and grip strength in level of performance and change across time in relation to impending death. Neurobiology of Aging 38, 68-72 (2016).

    9. Darwinism in the Nursery Southland Times (1892). https://paperspast.natlib.govt.nz/newspapers/ST18920123.2.30

    10. Gallup, A., White, D.D., & Gallup, G.G. Handgrip strength predicts sexual behavior, body morphology, and aggression in male collage students. Evolution & Human Behavior 28, 423-429 (2007).

    11. Dodds, R., et al. Does a heavy baby become a strong child? Grip strength at 4 years in relation to birthweight.” Journal of Epidemiology and Community Health 64, A11-A12 (2010).

    12. Ryan, T.M. & Shaw, C.N. Gracility of the modern Homo sapiens, skeleton is the result of decreased biomechanical loading. Proceedings of the National Academy of Sciences 112, 372-377 (2014).

    13. Futagi, Y., Toribe, Y., & Suzuki, Y. The grasp reflex and moro reflex in infants: Hierarchy of primitive reflex responses. International Journal of Pediatrics Article ID 191562 (2012).

    14. Walker, R., Haan, M., Kaplan, H., & Mcmillan, G. Age-dependency in hunting ability among the Ache of Eastern Paraguay. Journal of Human Evolution 42, 639-657 (2002).

    15. Capdarest-Arest, N., Gonzalez, J.P., & Türker, T. Hypotheses for ongoing evolution of muscles of the upper extremity. Medical Hypothesis 82, 452-456 (2014).
     
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  14. Prospector

    Prospector I am not a new member
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    non-nerd summary
    'Artificial photosynthetic system' using only common elements turns sunlight and CO2 into fuel
    There actually is an extremely powerful and efficient technology for capturing carbon dioxide and storing the energy from sunlight—it’s called photosynthesis. But the “engineering” built into plants by billions of years of evolution includes both complex chemical reactions and detailed structures that can be hard to reproduce in a way that works when, where, and how it’s needed by Planet Earth’s biggest energy consumers. That’s why an article in the current issue of the Proceedings of the National Academy of Sciences, reporting the work of French researchers, while preliminary, appears quite exciting.

    Their experiments demonstrate a system that buckles a photo-electric solar cell to the mineral perovskite in a “photo-voltaic minimodule” to convert carbon dioxide into the energy-rich fuels ethylene and ethane. At just 2.3% overall efficiency in converting sunlight into power, the results of the test may not seem all that fantastic. After all even consumer-grade photo-electric solar cells can run close to 20% efficiency in turning sunlight directly into electricity.

    But those efficiency numbers aren’t the end of the story. For one thing, the system built by the French team uses only “inexpensive all–earth-abundant” materials. There are no rare elements, or items restricted to just one part of the globe. Perovskites are a class of minerals that are based around crystals of calcium and titanium oxide. They are not only found in many areas, including Russia, Europe, and the United States, and they can also be manufactured in the lab. The photo-cell used was one that doesn’t require rare elements or high end components. And the metal used for the anode and cathode of the microcells was plain old copper rather than the much more expensive alternatives used in some systems. All of that means that the microcells should be able to be built cheaply, and not depend on materials that are hard to obtain, no matter where they are being made.

    What this system seems to offer is a low cost, common element model that doesn’t just solve the issue of turning sunlight into power, it also addresses the critical issue of energy storage by turning that sunlight into a form that’s easily stored, easily transported, and easily used. While the full cycle may be carbon neutral, the storage part of the cycle is carbon negative. And it could potentially create fuels that could drive most vehicles already on the world’s roads.

    As with almost every experiment when it comes to energy technology—whether that’s photovoltaics, batteries, or alternative storage—this paper represents very early days. But it’s an encouraging outcome that suggests that sunlight might not just power homes, but vehicles and other detached systems.

    Other systems have been build that top the 2.3% value obtained in this study. But those systems utilized elements like gallium, germanium, and iridium to achieve success. This system of “artificial photosynthesis” convert CO2 to hydrocarbons at a rate that doesn’t seem astounding … except that it appears to be possible to make at low cost and large scale. They leave room for that efficiency to be greatly increased by looking at all stages of the process for ways in which catalysts and electrolyzers could be tweaked.

    But the possibility of solar-powered systems that don’t just create electricity, they also create fuels that could be used to generate power during times when sunlight isn’t available (i.e night) or utilized in non-electric vehicles is certainly intriguing.
    very nerd actual article

    Low-cost high-efficiency system for solar-driven conversion of CO2 to hydrocarbons
    Tran Ngoc Huan, Daniel Alves Dalla Corte, Sarah Lamaison, Dilan Karapinar, Lukas Lutz, Nicolas Menguy, Martin Foldyna, Silver-Hamill Turren-Cruz, Anders Hagfeldt, Federico Bella, Marc Fontecave, and Victor Mougel
    PNAS May 14, 2019 116 (20) 9735-9740; first published March 27, 2019 https://doi.org/10.1073/pnas.1815412116
    1. Edited by Richard Eisenberg, University of Rochester, Rochester, NY, and approved March 5, 2019 (received for review September 6, 2018)
    Significance
    Carbon dioxide electroreduction may constitute a key technology in coming years to valorize CO2 as high value-added chemicals such as hydrocarbons and a way to store intermittent solar energy durably. Based on readily available technologies, systems combining a photovoltaic (PV) cell with an electrolyzer cell (EC) for CO2 reduction to hydrocarbons are likely to constitute a key strategy for tackling this challenge. However, a low-cost, sustainable, and highly efficient PV–EC system has yet to be developed. In this article, we show that this goal can be reached using a low-cost and easily processable perovskite photovoltaic minimodule combined to an electrolyzer device using the same Cu-based catalysts at both electrodes and in which all energy losses have been minimized.

    Abstract
    Conversion of carbon dioxide into hydrocarbons using solar energy is an attractive strategy for storing such a renewable source of energy into the form of chemical energy (a fuel). This can be achieved in a system coupling a photovoltaic (PV) cell to an electrochemical cell (EC) for CO2 reduction. To be beneficial and applicable, such a system should use low-cost and easily processable photovoltaic cells and display minimal energy losses associated with the catalysts at the anode and cathode and with the electrolyzer device. In this work, we have considered all of these parameters altogether to set up a reference PV–EC system for CO2 reduction to hydrocarbons. By using the same original and efficient Cu-based catalysts at both electrodes of the electrolyzer, and by minimizing all possible energy losses associated with the electrolyzer device, we have achieved CO2 reduction to ethylene and ethane with a 21% energy efficiency. Coupled with a state-of-the-art, low-cost perovskite photovoltaic minimodule, this system reaches a 2.3% solar-to-hydrocarbon efficiency, setting a benchmark for an inexpensive all–earth-abundant PV–EC system.

    The transformation of carbon dioxide is an energy-intensive process that must involve inexpensive sources of energy and high energy efficiency while maintaining the lowest possible cost. Artificial photosynthetic systems, which are technological devices that utilize sunlight as a source of energy and water as a source of electrons to convert CO2 into energy-dense organic compounds (fuels or other carbon-based feedstocks for the chemical industry), are attractive in that context. This can be achieved using a photovoltaic (PV) cell to provide photogenerated electrons and holes to an electrochemical cell (EC) for water oxidation at the anode and CO2 reduction at the cathode. Only a few examples of such PV–EC systems have been reported, predominantly leading to high CO or formate selectivity (13), and only two such systems have led to high hydrocarbons or alcohols selectivity (4, 5). Among them, the most efficient PV–EC systems have been based on costly components: A record 13% solar-to-CO conversion was achieved using a GaInP/GaInAs/Ge photovoltaic cell (3), while a 3% solar-to-hydrocarbon efficiency was reported with an iridium oxide anode coupled to a four-terminal III-V/Si tandem cell (5). Despite their unprecedented efficiency, these systems do not meet the critical requirement of using catalysts based only on earth-abundant elements and cost-efficient PV cells for large-scale use.

    The design of a cheap and high-efficiency PV–EC system indeed requires an integrative approach that takes the four following aspects into account: (i) the development of robust CO2 reduction (CO2R) and oxygen evolution reaction (OER) electrocatalysts with low overpotentials and based on earth-abundant metals; (ii) their operation in moderate pH conditions, limiting corrosion issues and electrolyte consumption and allowing for long-term operation; (iii) their integration into an electrolyzer especially designed to maximize their efficiency and limit electrical energy losses; and (iv) the final coupling of the electrolyzer to a low-cost PV system. This approach might result in lower current densities than currently reported using catalysts operating in highly basic media (68). However, such current densities are sufficient to match the current densities provided by state-of-the-art perovskite PV cells (9).

    Herein, we report an electrolyzer that uses the same copper-based catalyst at both the anode and cathode and achieves CO2 reduction to hydrocarbons (ethylene and ethane) with a 21% energy efficiency. Subsequent coupling of this system to a state-of-the-art perovskite PV minimodule demonstrated a 2.3% solar-to-hydrocarbons efficiency, setting a benchmark for an inexpensive all–earth-abundant PV–EC system.

    Results and Discussion
    Maximizing the Energy Efficiency.
    The efficiency of a CO2R/OER electrolyzer primarily depends on the activities of the catalysts, notably their ability to mediate both redox reactions with minimal overpotential losses. This is highly challenging as both anodic and cathodic reactions involve complex multielectron, multiproton reactions, especially when hydrocarbons are targeted. Furthermore, resistivity issues and membrane potential contributions can also significantly influence energy losses. The use of a single-compartment cell with anode and cathode in close proximity effectively solve membrane potential and resistivity-related issues (1, 4), but results in a gas mixture of the CO2 reduction products and the anodically evolved oxygen. The lack of electrode separation, however, increases the chance of gas crossover that has a deleterious effect on the Faradaic yield (FY) for CO2 reduction. Herein, we developed a two-compartment electrolyzer containing an anion-exchange membrane between the anodic and cathodic compartments. The overall cell potential can thus be expressed as the sum of the equilibrium potential, the kinetic overpotentials of CO2R and OER, and the resistive and concentration losses (Eq. 1):

    E(J)=Erev+ EΩ(J)+η(J)," role="presentation">E(J)=Erev+ EΩ(J)+η(J),
    [1]
    Erev=E0OER+E0CO2R;EΩ(J)=J×(Rmembrane+ Relectrolyte)×Select;η(J)=ηOER(J)–ηCO2R(J)+ηconc(J)," role="presentation">Erev=E0OER+E0CO2R;EΩ(J)=J×(Rmembrane+ Relectrolyte)×Select;η(J)=ηOER(J)–ηCO2R(J)+ηconc(J),
    where Erev is the reversible potential of the cell, EΩ is the ohmic drop, and η is the cell overpotential. J is the current density at the cathode, and Select is the surface of the electrodes.

    In this work, we take all of these parameters into consideration to develop a system with high selectivity toward hydrocarbons able to operate at currents over 25 mA⋅cm−2 and at a cell potential lower than 3 V, as low cell voltages are required for efficient coupling to photovoltaic cells.

    Electrocatalysts.
    Thus far, copper is the only metal that has shown high selectivity for CO2R to multicarbon products, particularly when prepared by reduction of CuO materials (1012). In addition, we and others have demonstrated that CuO can function as an efficient OER catalyst at the moderate pH conditions required for efficient CO2R (1316). Consequently, we selected a copper oxide-based catalyst for both anode and cathode material. This strategy presents the additional advantage of limiting the poisoning of the cathode by redepositing the metal used for the anode (3). This phenomenon has been previously observed in the context of CO2 reduction when using earth-abundant OER catalysts, and shown to result in a decrease of selectivity for CO2 reduction over time (1).

    Aiming at lowering mass transport losses (ηconc), we selected a dendritic nanostructured copper oxide material (DN-CuO) that we recently reported as highly efficient and stable OER catalyst (13). This material presents both a macroporous structure, provided by cavities larger than 50 µm, and a mesoporous structure resulting from the dendritic structure constituting the walls (SI Appendix, Fig. S1). This unique morphology ensures an efficient mass transfer of reactants and products while preserving a high electrochemical surface area.

    Electrolyzer.
    The design of the electrolyzer has a profound influence on the overall CO2 reduction performance, as it not only affects the cell voltage but also the selectivity of CO2R, the product separation, and the catalyst stability (17, 18). To reach the highest overall efficiency, we target minimizing both ohmic and mass transport losses (Eq. 1).

    The most straightforward way to reduce the overall cell resistance is to lower the interelectrode distance and to use a concentrated electrolyte solution. However, such an approach faces two main limitations: (i) in a CO2-saturated solution, a thin cathodic compartment favors formation and trapping of gas bubbles, thus strongly increasing the resistance of the cell, and (ii) a concentrated bicarbonate solution increases the catalytic selectivity for proton reduction at the expense of CO2 reduction, as shown here and in previous reports (4, 19, 20). Optimal results were obtained using a 7-mm interelectrode distance and a 0.1 M cesium bicarbonate (CsHCO3) CO2-saturated (pH 6.8) solution as the cathodic electrolyte combined with a 0.2 M cesium carbonate (Cs2CO3) solution (pH 11) as the anodic electrolyte. We showed that larger concentrations of the electrolytes, while decreasing the overall cell resistivity, lowered faradaic efficiency for CO2 reduction (SI Appendix, Fig. S18). Similarly, we observed that using other alkali-metal cations resulted in an overall decrease in current for the same applied potential (SI Appendix, Fig. S19). Multiple reports have shown the beneficial influence of large alkali cations on both the selectivity for multicarbon products in CO2 reduction and on lowering the overpotential for water oxidation (21, 22). Using HCO3− as the charge carrier for both the anodic and cathodic compartments together with an anion exchange membrane (AEM) allows for continuous operation of the system at high current densities: continuous CO2 bubbling in the catholyte regenerates the diffused bicarbonate anions. In addition, the moderate pH difference between the anodic and cathodic compartment allows a minimal contribution of the pH gradient to the membrane potential.

    One of the key factors lowering the efficiency of CO2 conversion is mass transfer of CO2 to the cathode surface. This is especially true in aqueous solution because of the low solubility of CO2. To overcome this limitation, we used a continuous-flow electrochemical cell in which the anolyte and catholyte are continuously flowed through the system. Constant saturation in CO2 is ensured by continuously purging the catholyte with CO2 in a separate compartment, which additionally continuously evacuates the reaction products. A schematic representation of the electrolyzer cell used here is given in SI Appendix, Figs. S2 and S3.

    Electrocatalytic Performances.
    Linear sweep voltammetry (LSV) was carried out at 10 mV⋅s−1 to evaluate the electrocatalytic activity of the DN-CuO electrodes for both CO2 reduction and water oxidation using this setup (Fig. 1A). The low cathodic onset potential of −0.3 V vs. reversible hydrogen electrode (RHE) and the high current densities (up to 25 mA⋅cm−2 at −0.95 V vs. RHE) illustrates the excellent CO2R electrocatalytic activity of DN-CuO, reported here. The anodic catalytic wave shows a similar onset potential for water oxidation as reported in our previous work (13), but accompanied with an increased current density, illustrating the beneficial influence of the electrolyzer system on the catalytic performance. The JE curve of the electrolyzer cell (Fig. 1B) shows that a current density of 25 mA⋅cm−2 can be obtained at a cell potential below 3 V, a consequence of the low resistivity of the electrolyzer. The different contributions to the overall cell potential are detailed in SI Appendix, Fig. S4, presenting the equivalent circuit diagram of the electrolyzer cell.

    (A) LSV of 1-cm2 DN-CuO cathode (red) and anode 1 (blue), using a scan rate of 10 mV⋅s−1 (currents are uncorrected for resistive losses incurred within the electrolyte; all current densities are based on projected geometric area). (B) JE curve of the electrolyzer cell using 1-cm2 DN-CuO electrodes. (C) Faradaic yields (FYs) for CO2 reduction products using 1-cm2 DN-CuO cathode at different potentials. All measurements were carried out using the electrolyzer cell described in the main text and SI Appendix, Fig. S2 using an AEM separating the cathodic (CO2-saturated 0.1 M CsHCO3) and anodic (0.2 M Cs2CO3) compartments. Constant CO2 saturation was ensured by continuous sparging of the cathodic electrolyte with CO2 at 2.5 mL⋅min−1. FY values are detailed in SI Appendix, Table S1, and error bars are provided in SI Appendix, Fig. S8. Ecell is the electrolyzer cell potential, and Ecathode is the applied cathode potential.
    " data-icon-position="" data-hide-link-title="0">[​IMG]

    Fig. 1.
    (A) LSV of 1-cm2 DN-CuO cathode (red) and anode 1 (blue), using a scan rate of 10 mV⋅s−1 (currents are uncorrected for resistive losses incurred within the electrolyte; all current densities are based on projected geometric area). (B) JE curve of the electrolyzer cell using 1-cm2 DN-CuO electrodes. (C) Faradaic yields (FYs) for CO2 reduction products using 1-cm2 DN-CuO cathode at different potentials. All measurements were carried out using the electrolyzer cell described in the main text and SI Appendix, Fig. S2 using an AEM separating the cathodic (CO2-saturated 0.1 M CsHCO3) and anodic (0.2 M Cs2CO3) compartments. Constant CO2 saturation was ensured by continuous sparging of the cathodic electrolyte with CO2 at 2.5 mL⋅min−1. FY values are detailed in SI Appendix, Table S1, and error bars are provided in SI Appendix, Fig. S8. Ecell is the electrolyzer cell potential, and Ecathode is the applied cathode potential.

    Controlled-potential electrolysis was carried out for 1 h at various fixed cathode potentials (SI Appendix, Fig. S5). Identification and quantification of the gas-phase products from the cathodic compartment were achieved by on-line GC, while the liquid-phase products were analyzed by ion-exchange chromatography and NMR spectroscopy. Significant amounts of ethylene (C2H4) and ethane (C2H6) were obtained at applied potentials below −0.8 V vs. RHE (Fig. 1C). The highest selectivity for CO2 reduction (vs. H2 formation) and hydrocarbon production (vs. CO and HCOOH formation) was obtained at a cathode potential of −0.95 V vs. RHE (Fig. 1C and SI Appendix, Fig. S6). This corresponds to a cell potential of 2.95 V, at which a stable current density of 25 mA⋅cm−2 was obtained during 3-h electrolysis (SI Appendix, Fig. S7). In these conditions, CO2 reduction products accounted for a 62% FY, without loss of selectivity over the course of the electrolysis. Among the CO2 reduction products, C2H4 accounted for 57% (37% FY), C2H6 for 18% (12.8% FY), HCOOH for 11% (7% FY), and CO for 8% (5% FY) (partial currents for the different products are given in SI Appendix, Fig. S8). This high selectivity and production rate for hydrocarbons at such a low cell potential is unprecedented (4, 5) and corresponds to a record cell energy efficiency for hydrocarbons of 21% (calculated using the thermoneutral potential of C2H4 and C2H6; see SI Appendix, Table S2, for details). 13C-labeling experiments confirmed CO2 as the sole source of carbon for all carbon-containing products (SI Appendix, Fig. S9).

    To illustrate the advantages of using a continuous-flow electrolyzer cell, we tested the DN-CuO electrodes within a standard H-type electrochemical cell in which CO2 was continuously bubbled through the cathodic compartment, using the same electrolytes and anion-exchange membrane. The current density–voltage characteristic of this cell, displayed in SI Appendix, Fig. S10, indicates that while the overall onset potential for the electrolyzer is identical, the efficiency of the standard H-type electrolyzer is much lower than that of the electrolyzer cell developed in this work. This is clearly illustrated by the difference in cell potential required to obtain a stable current of 25 mA⋅cm−2; 4.8 V were needed in the H-type electrolyzer, which produced hydrocarbons with a 6% energy efficiency, compared with 2.95 V in the continuous-flow electrochemical cell developed here, which led to the aforementioned 21% energy efficiency for hydrocarbon production (see SI Appendix for details).

    Postcharacterization of the Cathode.
    The characterization of DN-CuO has been reported previously (13). It consists of a triple-layer structure with a metallic copper core covered by successive layers of Cu2O (∼200-nm thickness) and CuO (∼50-nm thickness) (Figs. 2 and 3A), both layers contributing to the good catalytic activity of the material (13). We characterized the DN-CuO cathode after 1-h electrolysis at −0.95 V vs. RHE in the optimized CO2 reduction conditions described above. Scanning electron microscopy (SEM) images (SI Appendix, Fig. S1) showed no significant change in the morphology of the electrode. To gain more insight on structural changes occurring upon reduction, scanning transmission electron microscopy (STEM) images, selected area electron diffraction (SAED) analysis, and elemental mapping of focused ion beam (FIB) cross-sections of the DN-CuO before and after electrolysis as a cathode were recorded (Figs. 2 and 3 CF and SI Appendix, Fig. S11). Both SAED patterns and elemental mapping images show that copper oxide was reduced to metallic copper under CO2 reduction conditions (SI Appendix, Fig. S11). Interestingly, the STEM images shows that during reduction the shape of the nanostructure and the external morphology of the electrode were retained while a thin outer layer of Cu nanoparticles appeared at the electrode surface, the internal structure revealing Kirkendall voids (Fig. 3 C and E) (23). The increased porosity of the electrode is confirmed by a slight increase in electrochemical surface area (23.1 cm2 after electrolysis vs. 20.6 cm2 before electrolysis). The nanostructuration of the material plays a critical role regarding its selectivity, as witnessed by the comparison with the parent crystalline Cu dendrites (13), showing <10% FY for ethylene at −0.95 V vs. RHE (SI Appendix, Fig. S12). Such a beneficial influence of cavities in Cu electrocatalysts for multicarbon products was recently demonstrated in the context of carbon monoxide electroreduction (24). This specific nanostructure does not change over prolonged electrolysis, as witnessed by the STEM characterization of FIB slices of the electrode after 3-h operation (SI Appendix, Fig. S13). Furthermore, only trace amounts of Cu (<0.02% of total electrodeposited Cu on DN-CuO cathode) were released in the electrolyte solution over 3-h electrolysis, as revealed by inductively coupled plasma (ICP) analysis (SI Appendix).

    Schematic view of the DN-CuO before (Top) and after (Bottom) CO2 electroreduction in 0.1 M CsHCO3.
    " data-icon-position="" data-hide-link-title="0">[​IMG]

    Fig. 2.
    Schematic view of the DN-CuO before (Top) and after (Bottom) CO2 electroreduction in 0.1 M CsHCO3.

    STEM–high-angle annular dark-field analysis of FIB cross-sections of DN-CuO before (A and B) and after (CE) 1-h electroreduction of CO2 at −1.0 V vs. RHE in CO2-saturated 0.1 M CsHCO3. (BD) STEM–energy-dispersive X-ray spectroscopy analyses (Cu in red, O in green). (E and F) Electron energy loss spectroscopy analysis of the axis indicated in E, identifying Cu0 as the main oxidation state (28) at the surface of the electrode after 1-h electroreduction of CO2 at −1.0 V vs. RHE in CO2-saturated 0.1 M CsHCO3.
    " data-icon-position="" data-hide-link-title="0">[​IMG]

    Fig. 3.
    STEM–high-angle annular dark-field analysis of FIB cross-sections of DN-CuO before (A and B) and after (CE) 1-h electroreduction of CO2 at −1.0 V vs. RHE in CO2-saturated 0.1 M CsHCO3. (BD) STEM–energy-dispersive X-ray spectroscopy analyses (Cu in red, O in green). (E and F) Electron energy loss spectroscopy analysis of the axis indicated in E, identifying Cu0 as the main oxidation state (28) at the surface of the electrode after 1-h electroreduction of CO2 at −1.0 V vs. RHE in CO2-saturated 0.1 M CsHCO3.

    PV–EC Coupling.
    A PV–EC system has the advantage of relying on mature technologies benefiting from advanced experience of the industry innovations and continuously decreasing costs (25). However, while the separation of light capture and catalysis within two different devices allows for independent optimization and better control of the performances and scalability, correct matching of the PV power output to the number and sizing of EC cells is challenging. When a solar cell and an electrolyzer are directly connected, the electrical circuit requires the operating current and voltage to be the same for the two devices, and their values are determined by the crossing point between the current–voltage curves for the two devices. More specifically, to reach the highest efficiency: (i) the operating point (current, voltage) of the device must be as close as possible to the maximum power point for solar-to-electric energy conversion, and (ii) this working cell potential must correspond to the potential at which the highest selectivity for the products of interest, in this case hydrocarbons, is obtained.

    In this study, we used triple cation perovskite solar cells stabilized with a photocured coating (26). The typical current–voltage characteristic of a single PV cell (0.25 cm2) under 1 sun (AM 1.5G; 100 mW⋅cm−2) is shown in SI Appendix, Fig. S14. It shows a short-circuit photocurrent of 6.8 mA and a solar-to-electrical energy conversion (ηS-E) of 18.5%. To provide a PV voltage and current density compatible with the electrolyzer conditions required for the most selective transformation of CO2 to hydrocarbons, we built a minimodule constituted by two series of three perovskite solar cells connected in parallel (SI Appendix, Fig. S15). The photovoltaic current–voltage characteristic of this minimodule is presented in Fig. 4A (black squares), which shows a maximum ηS-E of 17.5% at 10.0 mA and 2.45 V (SI Appendix, Fig. S16), slightly decreased with respect to a single module. On the basis of the polarization curves presented in Fig. 1, the geometric surface areas of the cathode and the anode were adjusted to 0.35 and 0.85 cm2, respectively, for optimal match between the current–voltage characteristics of the electrolyzer cell and of the minimodule. The measured operating current of the electrolyzer cell at various potentials is shown in Fig. 4A, the theoretical operating point of the PV–EC system being given by the intersection with the PV current–voltage characteristic. With this setup, stable currents were obtained and high selectivity for C2 hydrocarbons was preserved over more than 6-h operation time (SI Appendix, Fig. S17). When both systems were connected, without external bias and under a constant AM 1.5G illumination, a stable current of 6.0 ± 0.2 mA (corresponding to a current density of ∼18 mA⋅cm−2 at the cathode) and a potential of 2.8 ± 0.02 (V) were recorded at the electrolyzer terminals. The system showed a stable current over 50-min electrolysis (Fig. 4B), during which time CO2R products were continuously analyzed by on-line GC. Selectivity did not vary during the run, C2H4 and C2H6 being obtained as the main products with an average FY of 40.5% (34% for C2H4 and 6.5% for C2H6), together with CO and HCOOH in 4.8% and 6.4% FY, respectively. Concomitant hydrogen production was observed with 42.2% FY. The lower selectivity of the electrolyzer using smaller electrodes can be explained by the slightly more negative potential of the cathode when a smaller cathode size is used. These measured current densities and FY allowed determining a solar-to-hydrocarbon (ethylene and ethane) efficiency of 2.3% (SI Appendix). This high efficiency constitutes a benchmark for solar-to-hydrocarbon products when using easily processable perovskite PV cells and earth-abundant metal catalysts (see SI Appendix, Table S2 for comparison with other PV–EC systems).

    (A) Current–potential characteristic of the perovskite minimodule under 1 sun, AM 1.5G illumination (black squares) and measured operating current of the electrolyzer cell (geometric areas of cathode, 0.35 cm2, and anode, 0.85 cm2; current measured after 5-min electrolysis) at various potentials (red dots). (B) Electrolyzer cell current as a function of photoelectrolysis time using the perovskite minimodule as the sole energy source.
    " data-icon-position="" data-hide-link-title="0">[​IMG]

    Fig. 4.
    (A) Current–potential characteristic of the perovskite minimodule under 1 sun, AM 1.5G illumination (black squares) and measured operating current of the electrolyzer cell (geometric areas of cathode, 0.35 cm2, and anode, 0.85 cm2; current measured after 5-min electrolysis) at various potentials (red dots). (B) Electrolyzer cell current as a function of photoelectrolysis time using the perovskite minimodule as the sole energy source.

    Conclusions
    In this work, we have elaborated an artificial photosynthetic system based on nonnoble metals and inexpensive material exclusively able to convert CO2 to hydrocarbons with a benchmark solar-to-hydrocarbon efficiency of 2.3%. This could be achieved through (i) the demonstration that a dendritic nanostructured copper oxide material behaves as a highly efficient electrocatalyst for both OER and CO2R and can be used both at the anode and the cathode, thus allowing to reduce production cost and issues related to metal contaminant deposit at the cathode during operation; (ii) a thorough consideration of all of the possible losses in the electrolyzer system resulting from hardware and catalysts issues, which allowed designing a tailor-made electrolyzer for overall CO2 reduction to hydrocarbons with a 21% energy efficiency.

    Materials and Methods
    Additional details regarding the materials and methods may be found in SI Appendix.

    General Considerations.
    Electrocatalytic measurements and electrolysis experiments were carried out using a Bio-logic SP300 potentiostat.

    Photovoltaic characterization was carried out by using solar simulator system, Newport’s Oriel Sol3A class AAA solar simulator (model 94083A) with certified 8″ × 8″ homogeneity under 1-sun illumination.

    H2 and gaseous CO2 reduction products were analyzed by GC (Multi-Gas Analyzer #5; SRI Instruments), equipped with Haysep D and MoleSieve 5A columns and thermal conductivity detector and flame ionization detector with methanizer using argon as a carrier gas. GC was calibrated by using a standard gas mixture containing 2,500 ppm of H2, CO, CH4, C2H4, C2H6, C3H6, C3H8, C4H8, and C4H10 in CO2 (Messer). The liquid-phase products were quantified using ionic exchange chromatography (formate and oxalate; 883 Basic IC; Metrohm) and NMR spectroscopy (Bruker AVANCE III 300 spectrometer). Fourier-transform infrared spectroscopy measurements were carried out using a SHIMADZU IR Affinity-1S spectrometer.

    SEM images were acquired using a Hitachi S-4800 scanning electron microscope. Transmission electron microscopy images were obtained on a JEM-2010F transmission electron microscope (JEOL) with an accelerating voltage of 200 kV.

    CuSO4·5H2O (99.9%), H2SO4 (99.8%), CsHCO3 (99.8%), Cs2CO3 (99.9%), and 13C-labeled CO2 (99 atom % 13C, <3 atom % 18O) were purchased from Sigma-Aldrich as used without further purification. DN-CuO electrodes and Cu dendrites were prepared according to previously reported procedure (13).

    Cu content in the electrolyte solutions was determined by ICP-AES analysis using a Thermo Fisher iCAP 6000 device instrument.

    Solar Cells Preparation.
    Substrate preparation and Li-doping TiO2.
    Nippon Sheet Glass 10 Ω/sq was cleaned by sonication in 2% Hellmanex water solution for 30 min. After rinsing with deionized water and ethanol, the substrates were further cleaned with UV ozone treatment for 15 min. Then, a 30-nm-thick TiO2 compact layer was deposited on FTO via spray pyrolysis at 450 °C from a precursor solution of titanium diisopropoxide bis(acetylacetonate) in anhydrous ethanol. After the spraying, the substrates were left at 450 °C for 45 min and left to cool down to room temperature. Then, a mesoporous TiO2 layer was deposited by spin coating (SPIN150i model, s/n R050962, SPS-Europe GmbH) for 20 s at 4,000 rpm with a ramp of 2,000 rpm⋅s−1, using 30-nm particle paste (Dyesol 30 NR-D) diluted in ethanol to achieve 150- to 200-nm-thick layer. After spin coating, the substrates were immediately dried at 100 °C for 10 min and then sintered again at 450 °C for 30 min under dry airflow.

    Li-doping of mesoporous TiO2 was accomplished by spin coating a 0.1 M solution of Li-TFSI in acetonitrile at 3,000 rpm for 30 s followed by another sintering step at 450 °C for 30 min. After cooling down to 150 °C, the substrates were immediately transferred in a nitrogen atmosphere glove box for depositing the perovskite films.

    Perovskite precursor solution.
    Perovskite solutions were prepared by using the organic cation iodide salts (Dyesol), lead compounds (TCI), and RBI (abcr GmbH) as follows. First, the mixed cation precursor solution was prepared with FAI (1 M), PbI2 (1.1 M), MABr (0.2 M), and PbBr2 (0.22 M) in anhydrous DMF:DMSO 4:1 (vol/vol). To achieve a triple cation composition, CsI (1.5 M) in DMSO was added to the mixed perovskite (MA/FA) precursor solution in a volume ratio of 5:95. To reach the final quadruple composition, RbI (1.5 M) in DMF:DMSO 4:1 (vol/vol) was added to the Cs/FA/MA triple cation perovskite in a volume ratio of 5:95 (27).

    Perovskite deposition.
    The perovskite solution were spin coated in a two-step program at 1,000 and 4,000 rpm for 10 and 30 s, respectively. During the second step, 200 μL of chlorobenzene was poured on the spinning substrate 20 s before the end of the program. The substrates were then annealed (at 100 °C, unless stated otherwise) for 1 h in a nitrogen-filled glove box.

    Hole transporting layers.
    After the perovskite annealing, the substrates were cooled down for a few minutes, and a spiro-OMeTAD (Merck) solution (70 mM in chlorobenzene) was spin-coated at 4,000 rpm for 20 s. Spiro-OMeTAD was doped with bis(trifluoromethylsulfonyl)imide lithium salt (Li-TFSI) (Sigma-Aldrich), tris(2-(1H-pyrazol-1-yl)-4-tert-butylpyridine)-cobalt(III) tris(bis(trifluoromethylsulfonyl)imide) (FK209) (Dynamo), and 4-tert-butylpyridine (tBP) (Sigma-Aldrich). The molar ratios of additives for spiro-OMeTAD were 0.5, 0.03, and 3.3 for Li-TFSI, FK209, and tBP, respectively. Finally, 80 nm of gold top electrode were thermally evaporated under high vacuum.

    Perovskite solar cells were then stabilized with a photopolymerized coating accordingly to previously reported procedure (26).

    Flow Electrochemical Cell.
    The scheme of the flow electrochemical cell is presented in SI Appendix, Fig. S2. The distance between cathode and anode is 0.7 cm approximately. The cathode and anode compartment are separated by a Selemion AEM. The geometrical surface area of the working electrodes was chosen to 1 cm2 in all of this study, unless otherwise specified. Ag wire was used as the reference electrode and placed in both compartments, and was calibrated with an aqueous Ag/AgCl reference electrode before each experiment. The electrode potentials were referred to RHE according to the following formula:

    E(vs.&#x2009;RHE)=E(vs.&#x2009;Ag&#x2009;wire)+&#x394;E+0.2+0.059&#xD7;pH." role="presentation">E(vs. RHE)=E(vs. Ag wire)+ΔE+0.2+0.059×pH.

    The potential difference (ΔE) between the Ag wire and the Ag/AgCl electrode was determined using the E1/2 potential of K3Fe(CN)6 in 0.1 M CsHCO3 solution as a reference. Unless otherwise stated, catalytic activity was investigated in this setup using CO2-saturated 0.1 M CsHCO3 (pH 6.8) at the cathode and 0.2 M Cs2CO3 (pH 11.0) at the anode, flowed through the two compartments at a constant flow of 1.0 mL⋅min−1. Constant CO2 saturation of the catholyte was ensured by continuous sparging with CO2 at 2.5 mL⋅min−1.

    Acknowledgments
    We acknowledge Dr. David Troadec and the French RENATECH Network for the preparation of FIB cross-sections and Domitille Giaume for her help with ICP-MS analyses. We thank Sphere Energy (https://www.sphere-energy.eu/) for the realization of the electrolyzer cell. F.B. thanks Politecnico di Torino and Compagnia di San Paolo for the financial support through the call “Metti in rete la tua idea di ricerca” (PEPPY project). V.M. acknowledges financial support from CNRS–Cellule Energie and Fondation of College de France for the acquisition of the flow electrochemical system.
     
  15. HuskerInMiami

    HuskerInMiami Well-Known Member
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    Miami DolphinsNebraska Cornhuskers

    Can I get an even more dumbed down version?
     
    a.tramp likes this.
  16. angus

    angus Well-Known Member
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    Sun---->natural gas
     
  17. Prospector

    Prospector I am not a new member
    Donor
    Utah UtesArkansas Razorbacks

    A radiative cooling structural material

    A stronger, cooler wood
    One good way to reduce the amount of cooling a building needs is to make sure it reflects away infrared radiation. Passive radiative cooling materials are engineered to do this extremely well. Li et al. engineered a wood through delignification and re-pressing to create a mechanically strong material that also cools passively. They modeled the cooling savings of their wood for 16 different U.S. cities, which suggested savings between 20 and 50%. Cooling wood would be of particular value in hot and dry climates.

    Science, this issue p. 760
    Abstract
    Reducing human reliance on energy-inefficient cooling methods such as air conditioning would have a large impact on the global energy landscape. By a process of complete delignification and densification of wood, we developed a structural material with a mechanical strength of 404.3 megapascals, more than eight times that of natural wood. The cellulose nanofibers in our engineered material backscatter solar radiation and emit strongly in mid-infrared wavelengths, resulting in continuous subambient cooling during both day and night. We model the potential impact of our cooling wood and find energy savings between 20 and 60%, which is most pronounced in hot and dry climates.

    Buildings account for more than 40% of the total energy demand and 70% of electricity use in the United States, leading to an annual national energy bill of more than $430 billion. Heating and cooling accounts for ~48% of this energy use, making it the largest individual energy expense (1). In general, cooling is more challenging than heating because of the second law of thermodynamics (2). As a result, passive radiative cooling has become attractive for improving building energy efficiencies by providing a perpetual path to dissipate heat from these structures through the atmospheric transparent window into the ultracold universe with zero energy consumption. Nocturnal radiative cooling has been investigated on pigmented paints, dielectric coating layers, metallized polymer films, and even organic gases because of their intrinsic thermal emission properties (26). Daytime radiative cooling is more challenging, as natural high-infrared emissive materials also tend to absorb visible wavelengths, though advances include using precision-designed nanostructures (7, 8) or hybrid optical metamaterials (9) to tailor material spectrum responses for continuous cooling. However, it remains a challenge to both manufacture and apply these structures at the size and scale required for construction purposes.

    Wood has been used for thousands of years and has emerged as an important sustainable building material to potentially replace steel and concrete because of its economic and environmental advantages (10). We engineered wood by complete delignification followed by mechanical pressing to render a structural material (Fig. 1, A and B) with daytime subambient cooling effects (figs. S1 to S8). We used scanning electron microscopy (SEM) to show that the wood exhibits multiscale cellulose fibers or fiber bundles (Fig. 1C and figs. S9 to S11). Our cooling wood is composed of cellulose nanofibers partially aligned in the tree’s growth direction (Fig. 1D and fig. S11); these fibers are nonabsorbing in the visible range (figs. S12 to S15). The multiscale fibers and channels (fig. S16) function as randomized and disordered scattering elements for an intense broadband reflection at all visible wavelengths (Fig. 1E and figs. S17 and S18). Meanwhile, the molecular vibration and stretching of cellulose in cooling wood facilitate strong emission in the infrared (Fig. 1F). The heat flux emitted by the cooling wood exceeds the absorbed solar irradiance, resulting in passive subambient radiative cooling for both day and night. The delignified and mechanically pressed wood also delivers mechanical strength and toughness that are, respectively, ~8.7 and 10.1 times the strength and toughness of natural wood. These findings establish cooling wood as a multifunctional structural material that may provide a path for improving the energy efficiency of buildings.

    Fig. 1 Cooling wood demonstrates passive daytime radiative cooling.
    Photos of a board of (A) natural wood and (B) cooling wood. (C) SEM image of the cooling wood showing the aligned wood channels. (D) SEM image of partially aligned cellulose nanofibers of the cooling wood. (E) Schematic showing the wood structure strongly scattering solar irradiance. (F) Schematic of infrared emission by molecular vibration of the cellulose functional groups. (G) Setup of the real-time measurement of the subambient cooling performance of the cooling wood.


    " data-icon-position="" data-hide-link-title="0">[​IMG]

    Fig. 1 Cooling wood demonstrates passive daytime radiative cooling.
    Photos of a board of (A) natural wood and (B) cooling wood. (C) SEM image of the cooling wood showing the aligned wood channels. (D) SEM image of partially aligned cellulose nanofibers of the cooling wood. (E) Schematic showing the wood structure strongly scattering solar irradiance. (F) Schematic of infrared emission by molecular vibration of the cellulose functional groups. (G) Setup of the real-time measurement of the subambient cooling performance of the cooling wood.

    The largely disordered mesoporous cellulose structures render the cooling wood extremely hazy. A reflective, hazy surface can effectively scatter incident light in a hemispherical solid angle, which is particularly desirable for building applications to avoid visual discomfort caused by strong specularly reflected light (11). We show the reflection haze spectra of the cooling wood with an incident angle of 8°, demonstrating that the material has an extremely high reflection haze of 96% on average (fig. S17). The high, diffusive reflectance in the solar radiation range leads to the bright whiteness of the cooling wood (Fig. 2A) (12). The higher reflection when the incoming polarization direction is along the fiber alignment direction is attributable to the strong scattering (fig. S18). We investigated the emissivity spectra of the cooling wood in the infrared range from 5 to 25 μm, i.e., covering the spectroscopically important wavelength range for room-temperature blackbodies (Fig. 2B). The cooling wood exhibits high emissivity (close to unity) in the infrared range, emitting strongly at all angles and radiating a net heat flux through the atmospheric transparency window (8 to 13 μm) to the cold sink of outer space in the form of infrared radiation. Thus, the cooling wood is black in the infrared range, a marked difference from its appearance in the solar spectrum, where it is white (i.e., simultaneously displaying a lack of absorption and high reflectivity). The infrared emissivity spectrum response shows negligible angular dependence (from 0° to 60°). The average emissivity across the atmospheric window is also greater than 0.9 for emission angles between ±60° (Fig. 2C), indicating a stable emitted heat flux when the cooling wood is aimed at different angles in relation to the sky, as it would be in practical applications. Figure S19 shows the Fourier transform infrared absorbance of the cooling wood. The strong emission from 8 to 13 μm is mainly contributed by the complex infrared emission of OH association and C–H, C–O, and C–O–C stretching vibrations between 770 and 1250 cm−1 (11). The cellulose exhibits the strongest infrared absorbance by OH and C–O centered at ~1050 cm−1 (9 μm) (11), which coincidently lies in the atmospheric transparency window (13). The high emissivity across the rest of the infrared spectrum results in radiative heat exchange between the cooling wood and the atmosphere (such as in the second atmospheric window between 16 and 25 μm), which further increases the overall radiative cooling flux when the surface temperature is close to that of the ambient environment (14).

    Fig. 2 Optical characterization and thermal measurement of cooling wood.
    (A) Absorption of the natural and cooling wood in the solar spectrum. (B) Infrared emissivity spectra of the cooling wood between 5 and 25 μm at different emission angles. (C) Polar distribution of the average emissivity across the atmospheric window of the cooling wood. (D) Schematic of the thermal box used to characterize the radiative cooling power and cooling temperature. PE, polyethylene. (E) Twenty-four–hour continuous measurement of the 200 mm–by–200 mm cooling wood. (Top) Measurement in Box one: Direct measurement of the radiative cooling power of the cooling wood. The heater was on, and a feedback control program maintained the wood temperature at the same temperature as the ambient environment. At this condition, the heating power is the same as the total radiative cooling power because all other heat fluxes are zero because of the zero-temperature difference. (Middle) Measurement in Box two: Steady-state temperature of the cooling wood. (Bottom) Temperature difference between the ambient surroundings and the cooling wood.


    " data-icon-position="" data-hide-link-title="0">[​IMG]

    Fig. 2 Optical characterization and thermal measurement of cooling wood.
    (A) Absorption of the natural and cooling wood in the solar spectrum. (B) Infrared emissivity spectra of the cooling wood between 5 and 25 μm at different emission angles. (C) Polar distribution of the average emissivity across the atmospheric window of the cooling wood. (D) Schematic of the thermal box used to characterize the radiative cooling power and cooling temperature. PE, polyethylene. (E) Twenty-four–hour continuous measurement of the 200 mm–by–200 mm cooling wood. (Top) Measurement in Box one: Direct measurement of the radiative cooling power of the cooling wood. The heater was on, and a feedback control program maintained the wood temperature at the same temperature as the ambient environment. At this condition, the heating power is the same as the total radiative cooling power because all other heat fluxes are zero because of the zero-temperature difference. (Middle) Measurement in Box two: Steady-state temperature of the cooling wood. (Bottom) Temperature difference between the ambient surroundings and the cooling wood.

    We demonstrated the subambient radiative cooling performance of the cooling wood during both day and night over 24-hour continuous thermal measurement in Cave Creek, Arizona (33°49′32″ N, 112°1′44″ W; 585-m altitude). We tested two sets of cooling wood, 200 mm by 200 mm in size, in two thermal boxes in parallel to monitor the subambient radiative cooling temperature directly as well as the cooling power with the assistance of a feedback-controlled heating system (Fig. 2D) (9). We elevated the two thermal boxes 1.2 m over the sunlight-shaded ground to avoid heat conducted from the ground to the boxes and overestimation of the thermal couples for ambient temperature measurement (fig. S3B). We found that the cooling wood had radiative cooling powers of 63 and 16 W/m2 during the night and daytime (between 11 a.m. and 2 p.m.), respectively, leading to an average cooling power of 53 W/m2 over the 24-hour period. We measured the steady-state radiative cooling temperature of the cooling wood synchronously in the second box, in which the Kapton heater was turned off. The cooling wood exhibits a radiative cooling temperature below ambient during both night and daytime (Fig. 2E). The average below-ambient temperature was >9°C during the night and >4°C during midday (between 11 a.m. and 2 p.m.). Both the natural wood and the cooling wood exhibit similar thermal conductivities between their top and bottom surfaces (fig. S20), and these values are higher than that of thermal insulation wood (15) because of the densified structure created by mechanical pressing. We observed the scattered clouds during the measurement, which slightly reduced the net radiative cooling effects (16). In addition, we used fluorosilane treatment, which can be used to make the wood superhydrophobic with a water contact angle of ~150° (fig. S21) and further improves the weatherability and protects the cooling wood from water condensate.

    The cooling wood is also mechanically stronger and tougher than natural wood because of the larger interaction area between exposed hydroxyl groups of the aligned cellulose nanofibers in the growth direction after lignin removal (Fig. 3A) (17). The cooling wood demonstrates a tensile strength as high as 404.3 MPa, which is ~8.7 times that of natural wood. An improved toughness of 3.7 MJ/m3 was also observed, which is 10.1 times that of natural wood (Fig. 3B). We observed a simultaneous enhancement in mechanical toughness (fig. S22), which is desirable in structural material design (1719). We attributed this to the energy dissipation enabled by repeated hydrogen-bond formation and/or breaking at the molecular scale in the delignified and mechanically pressed material.

    Fig. 3 Cooling wood as a multifunctional structural material.
    (A) Schematics showing the origin of the high mechanical strength from the molecular bonding of the aligned cellulose nanofibers. The (B) tensile strength and (C) specific ultimate strength of the cooling wood are compared with those of natural wood and some common metals and alloy (
    2123). (D and E) Scratch-hardness characterization of the natural wood and the cooling wood in three different directions. A, B, and C denote directions parallel, perpendicular, and at a 45° angle to the tree growth direction, respectively. (F) Performance comparison of cooling wood and natural wood. Error bars in (C) and (D) indicate measurement variations among the samples.


    " data-icon-position="" data-hide-link-title="0">[​IMG]
    Fig. 3 Cooling wood as a multifunctional structural material.
    (A) Schematics showing the origin of the high mechanical strength from the molecular bonding of the aligned cellulose nanofibers. The (B) tensile strength and (C) specific ultimate strength of the cooling wood are compared with those of natural wood and some common metals and alloy (2123). (D and E) Scratch-hardness characterization of the natural wood and the cooling wood in three different directions. A, B, and C denote directions parallel, perpendicular, and at a 45° angle to the tree growth direction, respectively. (F) Performance comparison of cooling wood and natural wood. Error bars in (C) and (D) indicate measurement variations among the samples.

    The ratio of mechanical strength to weight is a critical parameter in buildings, especially because of cost considerations (20). The specific tensile strength of the cooling wood reaches up to 334.2 MPa cm3/g (Fig. 3C), surpassing that of most structural materials, including Fe–Mn–Al–C steel, magnesium, aluminum alloys, and titanium alloys (2123). The mechanical scratch hardness of the cooling wood also shows great improvement compared with that of the untreated natural wood. As characterized by a linear reciprocating tribometer (fig. S23), the scratch hardness of the cooling wood reaches up to 175.0 MPa in direction C, which is 8.4 times that of natural wood (Fig. 3, D and E). Compared with natural wood, the scratch hardness of the cooling wood also increased by a factor of 5.7 and 6.5 in directions A and B, respectively. The flexural strength of cooling wood is ~3.3 times as high as that of natural wood (fig. S24, A to C). The axial compressive strength of the cooling wood is also much higher than that of natural wood. The cooling wood shows a high axial compressive strength of 96.9 MPa, which is 3.2 times as high as that of natural wood (fig. S24, D to F). Cooling wood also exhibits a toughness that is 5.7 times as high as that of natural wood (fig. S24, G and H).

    The cooling wood is superior to natural wood for building efficiency applications in terms of continuous cooling capability and mechanical strength (Fig. 3F). The properties of cooling wood, including continuous subambient cooling, high mechanical strength, bulk structure, low density, sustainability, and bulk fabrication process, make it attractive as a structural material when compared with other radiative cooling materials (79, 2427). Raman et al. (7) demonstrated a photonic approach to meet the stringent demands of high thermal emission in the mid-infrared and strong solar reflection using seven alternating layers of HfO2 and SiO2 of varying thicknesses. However, the material is difficult to execute at the scale required for buildings. Another metamaterial thin film was demonstrated to have the potential for scalable manufacturing (9) but cannot be used as a structural component. The influence on radiative cooling performance from local weather conditions, including wind speed, precipitable water, and cloud cover, has been investigated on large-scale radiative cooling metamaterial and systems (16). Durability for long-term outdoor applications must be considered if the cooling wood is to be utilized as a structural material on the external surfaces of buildings in the future. Surface treatment methods could improve the resistivity of the cooling wood against water (28), fire (29), ultraviolet exposure (30), and biological factors (31) to satisfy the need for long-term outdoor durability.

    The combination of the visible white (i.e., high solar reflectance) and infrared black (i.e., high infrared emissivity) properties of the cooling wood leads to a highly efficient radiative cooling material (Fig. 4, A and B). The mechanical strength also allows the cooling wood to be used as both roof and siding material without other mechanical support. We used EnergyPlus version 8 and the parameters listed in table S1 to model the potential energy savings of using cooling wood on exterior surfaces (wall siding and roofing membranes) of buildings. Our energy model accounts for a total heat balance on both the internal and external building enclosure surfaces, the heat transfer through the building enclosures, and heat sources and sinks, such as internal loads generated by equipment, occupants, and lighting. This modeling is governed by energy-balance equations for both the outside and inside surfaces of the building, as shown in table S2, which are solved simultaneously. To determine an annual rate of energy consumption, we solved the governing equations iteratively with an hourly time step over a year. The internal boundary conditions used an indoor air temperature set point of 24°C, and the external boundary conditions used hourly weather data for a typical meteorological year (32). These models use ray tracing for all components of radiative heat transfer, including direct and indirect fluxes, and fluxes reflected from both the ground and surrounding building surfaces.

    Fig. 4 Modeling energy savings by installing cooling-wood panels on roofing and external siding of midrise apartment buildings.
    (A) When used as a building material, the cooling wood exhibits high solar reflectance and high infrared emissivity. (B) Photo of a 5-cm-thick piece of cooling wood. (C) Total cooling energy savings per year and (D) percentage among all 16 cities. (E) Average cooling energy savings and percentage among all 16 cities. (F) Total predicted cooling energy savings of midrise buildings extended for all U.S. cities based on local climate zones.


    " data-icon-position="" data-hide-link-title="0">[​IMG]

    Fig. 4 Modeling energy savings by installing cooling-wood panels on roofing and external siding of midrise apartment buildings.
    (A) When used as a building material, the cooling wood exhibits high solar reflectance and high infrared emissivity. (B) Photo of a 5-cm-thick piece of cooling wood. (C) Total cooling energy savings per year and (D) percentage among all 16 cities. (E) Average cooling energy savings and percentage among all 16 cities. (F) Total predicted cooling energy savings of midrise buildings extended for all U.S. cities based on local climate zones.

    The building models that we used in this study are midrise apartment buildings across the United States, based on data from old (built before 1980) and new (built after 2004) structures provided by the U.S. Department of Energy Commercial Reference Buildings database (33). This building type is the most suitable among the reference buildings because of the importance of weather-related loads on the total building energy consumption (34). The energy modeling process established a baseline energy-consumption pattern for these old and new buildings and then modified the wall siding and roof membrane material properties on the basis of the cooling-wood performance to predict an energy-consumption pattern (figs. S25 and S26).

    Sixteen cities in the United States were selected for this study: Albuquerque (NM), Atlanta (GA), Austin (TX), Boulder (CO), Chicago (IL), Duluth (MN), Fairbanks (AK), Helena (MT), Honolulu (HI), Las Vegas (NV), Los Angeles (CA), Minneapolis (MN), New York City (NY), Phoenix (AZ), San Francisco (CA), and Seattle (WA) (35). These cities are representative of all U.S. climate zones, allowing us to extend the results of this study to the entire country. The modified building models use cooling wood in place of common wood siding, which is a layer of the roofing and siding assembly, to determine the passive cooling power generated as a result of the local weather.

    We determined the total cooling energy-saving patterns for the selected 16 cities and the percent savings relative to the baseline (Fig. 4, C and D). The midrise apartments built before 1980 and after 2004 are end members for assessing the energy savings, and buildings built in between will be between these two bounds. We found that an average of ~35% in cooling energy savings can be obtained for old midrise apartment buildings, and an average of ~20% can be obtained for new midrise apartments (Fig. 4E).

    The energy savings from the installation of the cooling wood on the exterior surface of these buildings show that, on average for old and new midrise apartments, Austin (22.9 MJ/m2), Honolulu (28.2 MJ/m2), Las Vegas (21.1 MJ/m2), Atlanta (17.1 MJ/m2), and Phoenix (32.1 MJ/m2) would have the highest energy savings among the selected 16 cities. Phoenix had the highest potential cooling savings because of its hot and dry climate. Therefore, cities in the Southwest may be the most suitable for the installation of this material to reduce energy consumption for cooling. However, if the cooling wood remains exposed during the winter months, the heating energy cost would subsequently increase. The offset of the increased heating energy costs and a more detailed analysis of the overall energy savings can be found in fig. S26. We predicted the cooling energy savings of midrise buildings extended for all U.S. cities on the basis of local climate zones. The results show that cities with hot and dry climates have the largest potential cooling energy savings. The energy-savings effect of cooling wood has the potential to relax the energy load associated with conditioning indoor spaces that accounts for 31% of the total building primary energy consumption (36). We also evaluated the effect of neighboring structures on the energy performance (figs. S27 to S30). Surrounding buildings decrease the cooling energy demand of the building covered with cooling wood because of the shading that the surrounding structures provide. Therefore, the potential cooling energy savings obtained by using cooling wood changes, on average, from 35% for an isolated building to 51% for the highest urban density in pre-1980 buildings and changes from 21 to 39% for post-2004 buildings.

    We developed a multifunctional, passive radiative cooling material composed of wood that can be fabricated by using a scalable bulk process to engineer its spectral response. The cooling wood exhibits superior whiteness, which originates from the low optical loss of the cellulose fibers and the material’s disordered photonic structure. The energy emitted within the infrared range of the cooling wood overwhelms the amount of solar energy received. We confirmed this cooling effect by real-time temperature measurements of natural and cooling-wood samples, in which the materials were exposed to the sky. Additionally, cooling wood is 8.7 times as strong as and 10.1 times as tough as natural wood. The intrinsic lightweight nature of the cooling wood has a specific strength three times that of widely used Fe–Mn–Al–C structural steel. This multifunctional, scalable cooling-wood material holds promise for future energy-efficient and sustainable building applications, enabling a substantial reduction in carbon emission and energy consumption.

    Supplementary Materials
    science.sciencemag.org/content/364/6442/760/suppl/DC1

    Materials and Methods

    Supplementary Text

    Figs. S1 to S30

    Tables S1 and S2

    References (3739)

    1. Tian Li1,*,
    2. Yao Zhai2,*,
    3. Shuaiming He1,*,
    4. Wentao Gan1,
    5. Zhiyuan Wei3,
    6. Mohammad Heidarinejad4,,
    7. Daniel Dalgo4,
    8. Ruiyu Mi1,
    9. Xinpeng Zhao2,
    10. Jianwei Song1,
    11. Jiaqi Dai1,
    12. Chaoji Chen1,
    13. Ablimit Aili2,
    14. Azhar Vellore5,
    15. Ashlie Martini5,
    16. Ronggui Yang2,6,
    17. Jelena Srebric4,
    18. Xiaobo Yin2,3,,
    19. Liangbing Hu1,
    See all authors and affiliations

    Science 24 May 2019:
    Vol. 364, Issue 6442, pp. 760-763
    DOI: 10.1126/science.aau9101

    cliffs:
    Scientists turn wood into a material that reflects heat, is as strong as steel
    A team of scientists from across the United States has figured out a way to process wood into a material that’s light and strong, and that has remarkable properties when it comes to reflecting heat. The experiment offers the potential of creating buildings that do such a good job of passive cooling that energy costs will be cut in half. With buildings already consuming 70% of electricity in the United States, and the climate crisis only increasing the demand for air conditioning, the potential impact of a better way to keep buildings cool is tremendous.

    In a paper published by Science, the team writes that the best way to save energy on a building is not to expend it in the first place, and that one way to do that is simply to reflect away heat. That way buildings, especially those in hot and dry areas, don’t have to expend even more energy on air conditioning. And their delignification process for wood seems to create a material that might be widely used, one that holds genuinely remarkable properties.

    Wood is composed of a number of materials, with cellulose in lignin at the top of the list. Most of the time, when people are talking about what gives wood its remarkable strength, the credit goes to the complex structure of lignin. But the team making the heat-reflecting wood went the other way. It processed it to break down the usually more resistant lignin, leaving the cellulose behind. Then it compressed the resulting cellulose into a sandwich of layers that create a “reflective, hazy surface” that’s very effective at scattering light.

    Many materials have been tested that can radiate away heat at night, but daytime radiative cooling is many times more difficult, as usually materials that can reflect infrared light (heat) absorb visible light and end up turning that light into heat. But the treated wood is very efficient at reflecting infrared light and visible light, with properties that match some heavily engineered metamaterials. But unlike lab-grown metamaterials, the compressed wood may be able to be produced on a scale needed for nationwide construction.

    One other result of the treatment is that the material is considerably stronger than the original wood. Its tensile strength (resistance to breaking) was not just 8.7 times that of natural wood, but greater than that of many forms of steel.

    Tensile strength isn’t the only important mechanical property, but the “cooling wood” seems to score high on all factors. It’s also 10 times tougher and more resistant to scratches, dents, and cracks than natural wood. That kind of number suggests that the cooling wood could be useful in roofing applications.

    The team studied older midrise apartment buildings in all climate zones across the United States and projects cooling-cost savings of approximately 35% by replacing some of the external structures with cooling wood. This kind of replacement strategy is one of the goals of the Green New Deal, which calls for retrofitting existing structures with energy-saving advances.

    From the information provided in the article, it appears that the lignin in the wood was broken down by boiling the wood in a solution of highly concentrated hydrogen peroxide. While this material is certainly reactive (you would not want to get it on your skin, or anywhere else), it’s also a chemical that’s readily produced and doesn’t leave any lasting noxious residue. If that represents the compete process—something that is not clear from the published article—and the process is as scalable as the authors suggest, there would seem to be extensive possibilities for a material that has both the cooling properties and strength they describe.

    The cooling properties of the material discussed in the publication would mean that buildings using it in cold climates would capture less heat. However, generating heat from electricity is far more efficient than cooling.

    Ordinary pressure-treated lumber has a tensile strength and compression comparable to that of untreated lumber, but is more resistant to breakdown by fungi or bacteria. Older treated lumber sometimes contained compounds that included arsenic or lead. Most treated lumber today contains copper chromate. The cooling wood, at least as described in the publication, seems to contain none of these chemicals.
     
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  18. bigred77

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  19. Kevintensity

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  20. Prospector

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    Breakthrough device can generate electricity from the night sky
    By Chris Ciaccia | Fox News


    An innovative new device is able to generate electricity from the night sky, according to a new study.

    The research, published in Joule, highlights a new device that uses radiative cooling and is able to generate enough electricity for an LED light bulb, even at night.

    "Remarkably, the device is able to generate electricity at night, when solar cells don't work," the study's lead author, Aaswath Raman, said in a statement. "Beyond lighting, we believe this could be a broadly enabling approach to power generation suitable for remote locations, and anywhere where power generation at night is needed."

    [​IMG]
    In this photograph, the thermoelectric generator harnesses temperature differences to produce renewable electricity without active heat input. Here it is generating light. (Credit: Aaswath Raman)

    The device, which is still a prototype, was put on a table, three feet above the ground on a rooftop in Stanford, Calif. It has a polystyrene enclosure that is covered in aluminized mylar to "minimize thermal radiation and protected by an infrared-transparent wind cover," according to the statement.

    It eventually drew heat from the surrounding air and released it back into the night sky through a simple black emitter.

    Radiative cooling, as described by Space.com, allows a surface to pass its heat to the atmosphere and is cooler than the air that surrounds it.

    "This phenomenon explains how frost forms on grass during above-freezing nights, and the same principle can be used to generate electricity, harnessing temperature differences to produce renewable electricity at night, when lighting demand peaks," the statement added.

    Raman and the other researchers believe that if they're able to make some modifications, the device could be used on a wider scale and also in particularly hot and dry climates.

    ARMY EYES PEARLS IN INNOVATING PROJECT TO BOLSTER BODY ARMOR

    "Our work highlights the many remaining opportunities for energy by taking advantage of the cold of outer space as a renewable energy resource," Raman added. "We think this forms the basis of a complementary technology to solar. While the power output will always be substantially lower, it can operate at hours when solar cells cannot."
     
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  21. Aaron Hernandez

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    Another thermoelectric breakthrough:

    A new way to turn heat into useful energy
    Capturing heat that otherwise would have been lost
    Date:
    September 23, 2019
    Source:
    Ohio State University
    Summary:
    Scientists have figured out how to capture heat and turn it into electricity. The discovery could create more efficient energy generation from heat in things like car exhaust, interplanetary space probes and industrial processes.

    An international team of scientists has figured out how to capture heat and turn it into electricity.

    advertisement
    The discovery, published last week in the journal Science Advances, could create more efficient energy generation from heat in things like car exhaust, interplanetary space probes and industrial processes.

    "Because of this discovery, we should be able to make more electrical energy out of heat than we do today," said study co-author Joseph Heremans, professor of mechanical and aerospace engineering and Ohio Eminent Scholar in Nanotechnology at The Ohio State University. "It's something that, until now, nobody thought was possible."

    The discovery is based on tiny particles called paramagnons -- bits that are not quite magnets, but that carry some magnetic flux. This is important, because magnets, when heated, lose their magnetic force and become what is called paramagnetic. A flux of magnetism -- what scientists call "spins" -- creates a type of energy called magnon-drag thermoelectricity, something that, until this discovery, could not be used to collect energy at room temperature.

    "The conventional wisdom was once that, if you have a paramagnet and you heat it up, nothing happens," Heremans said. "And we found that that is not true. What we found is a new way of designing thermoelectric semiconductors -- materials that convert heat to electricity. Conventional thermoelectrics that we've had over the last 20 years or so are too inefficient and give us too little energy, so they are not really in widespread use. This changes that understanding."

    Magnets are a crucial part of collecting energy from heat: When one side of a magnet is heated, the other side -- the cold side -- gets more magnetic, producing spin, which pushes the electrons in the magnet and creates electricity.

    The paradox, though, is that when magnets get heated up, they lose most of their magnetic properties, turning them into paramagnets -- "almost-but-not-quite magnets," Heremans calls them. That means that, until this discovery, nobody thought of using paramagnets to harvest heat because scientists thought paramagnets weren't capable of collecting energy.

    What the research team found, though, is that the paramagnons push the electrons only for a billionth of a millionth of a second -- long enough to make paramagnets viable energy-harvesters.

    The research team -- an international group of scientists from Ohio State, North Carolina State University and the Chinese Academy of Sciences (all are equal authors on this journal article) -- started testing paramagnons to see if they could, under the right circumstances, produce the necessary spin.

    What they found, Heremans said, is that paramagnons do, in fact, produce the kind of spin that pushes electrons.

    And that, he said, could make it possible to collect energy.

    Ohio State graduate student Yuanhua Zheng is also an author on this work. The research was conducted in partnership with additional researchers at the U.S. Department of Energy's Oak Ridge National Laboratory and was supported by the National Science Foundation, the Air Force Office of Scientific Research and the U.S. Department of Energy.
     
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  22. Prospector

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    Near-Infinite-Lasting Power Sources Could Derive from Nuclear Waste
    Scientists from the University of Bristol are looking to recycle radioactive material.

    [​IMG]
    By Fabienne Lang
    January 21, 2020

    When you hear about radioactive material you tend to think that it would be best not to go near it. A team of physicists and chemists from the University of Bristol in England don't quite think that way, though.

    The team, in fact, hope to recycle radioactive material from disused nuclear power plants in the South West of England to create diamond battery power — ultra-long-lasting power sources.

    RELATED: EVERYTHING YOU NEED TO KNOW ABOUT NUCLEAR POWER PLANTS

    Work is already underway
    Radioactive waste products are already being removed from the Berkeley Power Station. By removing carbon-14 isotopes from the irradiated graphite, the time and cost of the decommissioning program of the former nuclear power plant could be vastly lowered.

    The Berkeley Power Station has been out of use since 1989, and it's only safe now to start removing its radioactive waste products
    [​IMG]
    Graphite blocks when in a nuclear reactor, Source: EDF Energy
    The second nuclear power plant the team has in mind is in Oldbury, which is in its early decommissioning stages. These two sites, amongst others across the U.K., hold huge amounts of irradiated graphite. This graphite holds carbon-14 isotope, the carbon that could be recycled to generate long-lasting power.

    Near-infinite duration of power
    The researchers from the University of Bristol created a diamond that, when placed in a radioactive field, can create an electrical current. Then, by using the carbon-14 isotope, which has a half-life of 5,730 years, a near-infinite amount of power is available.

    The work is part of the, Advanced Self-Powered sensor units in Intense Radiation Environments, or ASPIRE, project.

    Lead researcher of the project, Professor Tom Scott from the School of Physics said "Over the past few years we have been developing ultra-low powered sensors that harvest energy from radioactive decay. This project is at quite an advanced stage now and we have tested the batteries in sensors in places as extreme as the top of a volcano!"

    These batteries could be used in a number of useful environments, such as where conventional power sources can't be reached, or for certain medical purposes like pacemakers and hearing aids. They could even be used to provide power to spacecraft or satellites.

    Professor Scott mentioned "With the majority of the UK's nuclear power plants set to go offline in the next 10-15 years this presents a huge opportunity to recycle a large amount of material to generate power for so many great uses."
     
  23. BP

    BP Bout to Regulate.
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  24. Aaron Hernandez

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    this is pretty neat, but I feel like from a PR perspective you’d have a tough time selling pacemakers and hearing aids powered by recycled radioactive material.
     
  25. WhiskeyDelta

    WhiskeyDelta Well-Known Member
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    People got used to carrying microwave transmitters in their pockets pretty quickly
     
  26. Mr Bulldops

    Mr Bulldops If you’re juiceless, you’re useless
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    To be fair, people that need pacemakers have probably already been shot full of radioactive material while the drs were trying to figure out if they needed a pacemaker
     
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  27. IV

    IV Freedom is the right of all sentient beings
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    Question: Does anyone have any literature on the amount of death needed to exert evolutionary pressure?
     
  28. Can I Spliff it

    Can I Spliff it Is Butterbean okay?
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    It doesnt need to be death. There was a study on the splitting of a frog population in 2 groups by some state government putting down a somewhat busy road, and the now-two-separated groups becoming incompatible sexually over a couple years.

    But if you're going the death route, its a lot of death to do it quickly
     
    #230 Can I Spliff it, Jun 24, 2021
    Last edited: Jun 24, 2021
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  29. IV

    IV Freedom is the right of all sentient beings
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    I was listening to the new LPOTL series about the Black Death in the 1300’s and they mentioned that to survive many people would abandon close friends and family including children. People think as much as 66% of Europe got smoked in a couple of decades. I was just tossing around the idea of whether or not this selected less empathetic more brutal people to survive.
     
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  30. IV

    IV Freedom is the right of all sentient beings
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  31. WhiskeyDelta

    WhiskeyDelta Well-Known Member
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    This time next year: Great Fresh Lake, Utah
     
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  32. angus

    angus Well-Known Member
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  33. RonBurgundy

    RonBurgundy Well-Known Member

    Garbage article is garbage
     
  34. Can I Spliff it

    Can I Spliff it Is Butterbean okay?
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    But ted cruz has been serving in congress for years now
     
    IV likes this.
  35. angus

    angus Well-Known Member
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    Expound please.
     
  36. RonBurgundy

    RonBurgundy Well-Known Member

    No



    It’s basically an enhanced version of ECMO, an existing therapy already in use. Article is flimsy on the science, because we’ve been able to keep organs and tissues alive in patients in permanent vegetative states for a long time, this technology basically has the potential to just do it better/intervene later than existing methods. Assuming it’s easy to set up and is practical (again article is weak on details.) Reanimation is a sensational exaggeration imo.
     
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  37. broken internet

    broken internet Everything I touch turns to gold.
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    Yeah, the thing about reanimating anything depends on the damage done to the cells. You get enough free radicals, it doesn't matter, the cell just won't work anymore, no matter what cocktail of drugs you inject. It's like putting gas in a car that's sat in a junkyard for 30 years and expecting it to start right up. There's a litany of things that need to happen in order for something to work.

    The cases of people freezing for extended periods of time and coming back to life are more intriguing to me:

    https://historyofyesterday.com/jean-hilliard-8ee1443c586f
     
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  38. angus

    angus Well-Known Member
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    Asshole


    Thanks
     
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  39. Arliden

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  40. beerme

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    Oh god this is wonderful. Do we finally get flying cars now?
     
  41. All_Luck

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    The fusion breakthrough was actually a much higher ratio than everyone assumed yesterday.

    LLNL’s experiment surpassed the fusion threshold by delivering 2.05 megajoules (MJ) of energy to the target, resulting in 3.15 MJ of fusion energy output, demonstrating for the first time a most fundamental science basis for inertial fusion energy (IFE)
     
    broken internet, IV, snowfx2 and 10 others like this.
  42. Can I Spliff it

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    First thing it mentions about what it helps with is weapons stockpile stewardship ahhhhhhh
     
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  43. WhiskeyDelta

    WhiskeyDelta Well-Known Member
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    TBF anyone who thinks this will result in unlimited free energy for all and not in hoarding it for military purposes has never met a capitalism.
     
  44. beerme

    beerme Well-Known Member
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    Does this not lead to more security by way of reducing world reliance on Saudi Arabia, Iran, Russia, etc? All rely heavily on oil exports as a % of their GDP
     
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  45. WhiskeyDelta

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    It’s likely still decades away from commercial use. Not saying it isn’t a good thing but I’m also pretty black pilled at this point.
     
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  46. beerme

    beerme Well-Known Member
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    how many decades months away from nuclear fusion powered military vehicles