University of Wisconsin-Madison scientists have found a way to nearly double the efficiency that a commonly used industrial yeast strain converts plant sugars to biofuel. The newly engineered “super yeast” could boost the economics of making ethanol, specialty biofuels and bioproducts.
Saccharomyces cerevisiae has been the baker’s and brewer’s yeast of choice for centuries, but it poses a unique challenge to researchers using it to make biofuel from cellulosic biomass such as grasses, woods, or the nonfood portion of plants. The world-famous microbe is highly adept at converting a plant’s glucose to biofuel but is otherwise a picky eater, ignoring the plant’s xylose, a five-carbon sugar that can make up nearly half of all available plant sugars.
Trey Sato, the Great Lakes Bioenergy Research Center (GLBRC) study’s lead researcher and a UW-Madison associate scientist said, “For cellulosic biofuels to become economically feasible, microbes need to be able to convert all of a plant’s sugars, including xylose, into fuel.”
In a study published in the journal PLOS Genetics, Sato and his GLBRC collaborators describe the isolation of specific genetic mutations that allow S. cerevisiae to convert xylose into ethanol, a finding that could transform xylose from a waste product into a source of fuel. To uncover these genetic mutations, the researchers had to untangle millions of years of evolution, teasing out what led S. cerevisiae to become so selective in its eating habits in the first place.
First, Sato and colleagues gave the yeast a choice akin to eating carrots for dinner or nothing at all, surrounding S. cerevisiae with xylose until it either reevaluated its distaste for xylose or died. It took 10 months and hundreds of generations of “directed evolution” for Sato and his colleagues, including co-corresponding authors Robert Landick, a UW-Madison professor of biochemistry, and Audrey Gasch, a UW- Madison professor of genetics, to create a strain of S. cerevisiae that could ferment xylose.
Once the researchers had isolated the super yeast they named GLBRCY128, they also needed to understand exactly how the evolution had occurred in order to replicate it. Gasch compared Y128’s genome to the original strain, combing through the approximately 5,200 genes of each to find four gene mutations responsible for the adapted behavior. To verify their finding, the researchers manually deleted these mutations from the parent strain, producing the same result.
Sato says this work could enable a wide variety of biofuels research going forward. With the technique for making Y128 published, researchers are free to make it themselves for the purposes of applying it to new biomass pretreatment technologies or to different plant materials. “Scientists won’t need to adapt their research to the process that we’re doing here,” he said. “They can just take our technology and make their own strain.”
Future research may also focus on the super yeast’s potentially powerful role in creating specialty biofuels and bioproducts.
“We want to take this strain and make higher-order molecules that can be further converted into jet fuels or something like isobutanol, lipids or diesel fuel,” said Sato. “And if we know how to better metabolize carbon, including xylose, anybody in theory should be able to rewire or change metabolic pathways to produce a variety of biofuel products.”
A spectacular result. And oddly, more natural than the genetic engineering that has so many unnerved. Directed or not, the discovery is a survival mechanism at work. Its an innovative, if patience demanding method. Well done Great Lakes Bioenergy Research Center! Congratulations on finding a new platform for biofuel development.
October 19, 2016 | Leave a Comment
Harvard School of Engineering and Applied Sciences researchers have made a discovery that could lay the foundation for quantum superconducting devices. Settle in, because this is one of those bleeding razor sharp edge technologies dealing with practical applications in quantum mechanics.
The Harvard breakthrough solves one the main challenges to quantum computing: how to transmit spin information through superconducting materials. Background:
Every electronic device – from a supercomputer to a dishwasher – works by controlling the flow of charged electrons. But electrons can carry so much more information than just charge; electrons also spin, like a gyroscope on axis.
Harnessing electron spin is really exciting for quantum information processing because not only can an electron spin up or down – one or zero – but it can also spin any direction between the two poles. Because it follows the rules of quantum mechanics, an electron can occupy all of those positions at once. Imagine the power of a computer that could calculate all of those positions simultaneously.
A whole field of applied physics, called spintronics, focuses on how to harness and measure electron spin and build spin equivalents of electronic gates and circuits.
By using superconducting materials through which electrons can move without any loss of energy, physicists hope to build quantum devices that would require significantly less power.
But there’s a problem.
According to a fundamental property of superconductivity, superconductors can’t transmit spin. Any electron pairs that pass through a superconductor will have the combined spin of zero.
In paper published in Nature Physics, the Harvard researchers found a way to transmit spin information through superconducting materials. There’s the breakthrough, but there is more cool stuff.
Amir Yacoby, Professor of Physics and of Applied Physics at SEAS and senior author of the paper said, “We now have a way to control the spin of the transmitted electrons in simple superconducting devices.”
It’s easy to think of superconductors as particle super highways but a better analogy would be a super carpool lane as only paired electrons can move through a superconductor without resistance.
These pairs are called Cooper Pairs and they interact in a very particular way. If the way they move in relation to each other (physicists call this momentum) is symmetric, then the pair’s spin has to be asymmetric – for example, one negative and one positive for a combined spin of zero. When they travel through a conventional superconductor, Cooper Pairs’ momentum has to be zero and their orbit perfectly symmetrical.
But if you can change the momentum to asymmetric – leaning toward one direction – then the spin can be symmetric. To do that, you need the help of some exotic (aka weird) physics.
Superconducting materials can imbue non-superconducting materials with their conductive powers simply by being in close proximity. Using this principle, the researchers built a superconducting sandwich, with superconductors on the outside and mercury telluride in the middle. The atoms in mercury telluride are so heavy and the electrons move so quickly, that the rules of relativity start to apply.
Hechen Ren, coauthor of the study and graduate student at SEAS explains, “Because the atoms are so heavy, you have electrons that occupy high-speed orbits. When an electron is moving this fast, its electric field turns into a magnetic field which then couples with the spin of the electron. This magnetic field acts on the spin and gives one spin a higher energy than another.”
So, when the Cooper Pairs hit this material, their spin begins to rotate.
Ren continues, “The Cooper Pairs jump into the mercury telluride and they see this strong spin orbit effect and start to couple differently. The homogenous breed of zero momentum and zero combined spin is still there but now there is also a breed of pairs that gains momentum, breaking the symmetry of the orbit. The most important part of that is that the spin is now free to be something other than zero.”
The team could measure the spin at various points as the electron waves moved through the material. By using an external magnet, the researchers could tune the total spin of the pairs.
Professor Yacoby sums up with, “This discovery opens up new possibilities for storing quantum information. Using the underlying physics behind this discovery provides also new possibilities for exploring the underlying nature of superconductivity in novel quantum materials.”
While the emphasis is on computing and storage for now with the Harvard team, what they have learned and discovered is sure to interest those in the energy fields. The part of our universe that is quantum is still a very raw and wide open frontier with little really known with absolute certainty, Theory abounds and is probably the facts, but as those facts solidify ideas for designs and engineering will appear and what that entails is anyone’s guess today.
MIT researchers have for the first time developed a supercapacitor that uses no conductive carbon at all. The new supercapacitors could potentially produce more power than existing versions of this technology.
Energy storage devices called supercapacitors have become a hot area of research, in part because they can be charged rapidly and deliver intense bursts of power. But current production supercapacitors use components made of carbon, which require high temperatures and harsh chemicals to produce.
The team’s findings have been published in the journal Nature Materials, in a paper by Mircea Dinca, an MIT associate professor of chemistry; Yang Shao-Horn, the W.M. Keck Professor of Energy; and four others.
Dinca said, “We’ve found an entirely new class of materials for supercapacitors.”
For years Dinca and his team have been exploring a class of materials called metal-organic frameworks, or MOFs, which are extremely porous, sponge-like structures. These materials have an extraordinarily large surface area for their size, much greater than the carbon materials do. That is an essential characteristic for supercapacitors, whose performance depends on their surface area. But MOFs have a major drawback for such applications: They are not very electrically conductive, which is also an essential property for a material used in a capacitor.
Dinca explained, “One of our long-term goals was to make these materials electrically conductive,” even though doing so “was thought to be extremely difficult, if not impossible.” But the material did exhibit another needed characteristic for such electrodes, which is that it conducts ions (atoms or molecules that carry a net electric charge) very well.
“All double-layer supercapacitors today are made from carbon,” Dinca says. “They use carbon nanotubes, graphene, activated carbon, all shapes and forms, but nothing else besides carbon. So this is the first noncarbon, electrical double-layer supercapacitor.”
One advantage of the material used in these experiments, technically known as Ni3(hexaiminotriphenylene)2, is that it can be made under much less harsh conditions than those needed for the carbon-based materials, which require very high temperatures above 800º Celsius and strong reagent chemicals for pretreatment.
The team says supercapacitors, with their ability to store relatively large amounts of power, could play an important role in making renewable energy sources practical for widespread deployment. They could provide grid-scale storage that could help match usage times with generation times, for example, or be used in electric vehicles and other applications.
The new devices produced by the MIT team, even without any optimization of their characteristics, already match or exceed the performance of existing carbon-based versions in key parameters, such as their ability to withstand large numbers of charge/discharge cycles. Tests showed they lost less than 10 percent of their performance after 10,000 cycles, which is comparable to existing commercial supercapacitors.
But that’s likely just the beginning, Dinca said. MOFs are a large class of materials whose characteristics can be tuned to a great extent by varying their chemical structure. Work on optimizing their molecular configurations to provide the most desirable attributes for this specific application is likely to lead to variations that could outperform any existing materials. “We have a new material to work with, and we haven’t optimized it at all,” he said. “It’s completely tunable, and that’s what’s exciting.”
While there has been much research on MOFs, most of it has been directed at uses that take advantage of the materials’ record porosity, such as for storage of gases. “Our lab’s discovery of highly electrically conductive MOFs opened up a whole new category of applications,” Dinca said. Besides the new supercapacitor uses, the conductive MOFs could be useful for making electrochromic windows, which can be darkened with the flip of a switch, and chemoresistive sensors, which could be useful for detecting trace amounts of chemicals for medical or security applications.
While the MOF material has advantages in the simplicity and potentially low cost of manufacturing, the materials used to make it are more expensive than conventional carbon-based materials, Dinca said. “Carbon is dirt cheap. It’s hard to find anything cheaper.” But even if the material ends up being more expensive, if its performance is significantly better than that of carbon-based materials, it could find useful applications, he said.
And a key advantage of that, he explained, is that “this work shows only the tip of the iceberg. With carbons we know pretty much everything, and the developments over the past years were modest and slow. But the MOF used by Dinca is one of the lowest-surface-area MOFs known, and some of these materials can reach up to three times more [surface area] than carbons. The capacity would then be astonishingly high, probably close to that of batteries, but with the power performance [the ability to deliver high power output] of supercapacitors.”
The research into super capacitors marches on. While the MIT team has a breakthrough here, the barium titanate crowd is far from finished off. The market is going to get choices and that is a very good thing indeed.
October 13, 2016 | Leave a Comment
Brookhaven National Laboratory scientists have discovered a new phenomenon of perovskite that could have practical applications. Perovskites are expected to have applications in solar cells, rechargeable battery electrodes, and water-splitting devices.
When one type of perovskite, known as BSCF for its constituents of barium, strontium, cobalt, and iron, is exposed to both water vapor and streams of electrons, it exhibits behavior that researchers had never anticipated: The material gives off oxygen and begins oscillating, almost resembling a living, breathing organism.
Yang Shao-Horn, the W.M. Keck Professor of Energy at MIT said the phenomenon was “totally unexpected” and may turn out to have some practical applications. She is the senior author of a paper describing the research that has been published in the journal Nature Materials. The paper’s lead author is Binghong Han PhD ’16, now a postdoc at Argonne National Laboratory.
The discovery is important because perovskite oxides are promising candidates for a variety of applications, including solar cells, electrodes in rechargeable batteries, water-splitting devices to generate hydrogen and oxygen, fuel cells, and sensors. In many of these uses, the materials would be exposed to water vapor, so a better understanding of their behavior in such an environment is considered important for facilitating the development of many of their potential applications.
In a quote, the press release compares the phenomena to cooking polenta. When the perovskite BSCF is placed in a vacuum in a transmission electron microscope (TEM) to observe its behavior, Shao-Horn said, “nothing happens, it’s very stable.” But then, “when you pump in low pressure water vapor, you begin to see the oxide oscillate.” The cause of that oscillation, clearly visible in the TEM images, is that “bubbles form and shrink in the oxide. It’s like cooking a polenta, where bubbles form and then shrink.”
The behavior was so unexpected in part because the oxide is solid and was not expected to have the flexibility to form growing and shrinking bubbles.
Shao-Horn said, “This is incredible. We think of oxides as brittle.” But in this case the bubbles expand and contract without any fracturing of the material. And in the process of bubble formation, “we are actually generating oxygen gas,” she said.
What’s more, the exact frequency of the oscillations that are generated by the forming and bursting bubbles can be precisely tuned, which could be a useful feature for some potential applications. “The magnitude and frequency of the oscillations depend on the pressure” of the vapor in the system, Shao-Horn said. And since the phenomenon also depends on the presence of electron beams, the reaction can be switched on and off at will by controlling those beams.
Shao-Horn also noted the effect is not just a surface reaction. The water molecules, which become ionized (electrically charged) by the electron beam, actually penetrate deep into the perovskite. “These ions go inside the bulk material, so we see oscillations coming from very deep,” she said.
The experiment used the unique capabilities of an “environmental” transmission electron microscope at Brookhaven National Laboratory, part of a U.S. Department of Energy-supported facility there. With this instrument, the researchers directly observed the interaction between the perovskite material, water vapor, and streams of electrons, all at the atomic scale.
Han noted that despite all the pulsating motion and the penetration of ions in and out of the solid crystalline material, when the reaction stops, the material “still has its original perovskite structure,” Han said.
Because this is such a new and intriguing finding, Shao-Horn said, “We still don’t understand in full detail” exactly how the reactions take place, so the research is continuing in order to clarify the mechanisms. “It’s an unexpected result that opens a lot of questions to address scientifically.”
While the initial experiments used electron beams, Shao-Horn is now asking if such behavior could also be induced by shining a bright light, which could be a useful approach for water splitting and purification – for example, using sunlight to generate hydrogen fuel from water or remove toxins from water.
Shao-Horn pointed out that most catalysts promote reactions only at their surfaces. The new fact that this reaction penetrates into the bulk of the material suggests that it could offer a new mechanism for catalyst designs, she said.
This is one of those stop and imagine basic research results. The intuition here of introducing water vapor into the experiment is just sublime. Perovskite is so new that this kind of information can only accelerate and intensify interest. Congratulations to this team for opening up the field far beyond what was on the table just a short while ago.
October 12, 2016 | Leave a Comment
Researchers from the Solar Energy Institute at the Universidad Politécnica de Madrid (UPM) are developing a new energy storage system in which the entry energy, either from solar energy or surplus electricity from a renewable power generation, is stored in the form of heat in molten silicon at very high temperature, around 1400° C.
The novel system was created allowing the storage of energy in molten silicon which is the most abundant element in Earth’s crust most often though of as sand. The system has patent pending status in the United States, and aims to develop a new generation of low cost solar thermal stations and becoming a innovative storage system of electricity and cogeneration for urban centers.
The research paper about the system has been published in the Energy Journal. The researchers aim to develop a new generation of low cost solar thermal stations and develop an innovative storage system of electricity and cogeneration for urban centers.
Silicon has unique properties that confer the ability to store more than 1 MWh of energy in a cubic meter, ten times more than using salts. Molten silicon is thermally isolated from its environment until such energy is demanded, when this occurs, the heat stored is converted into electricity.
Alejandro Datas, the research promoter of this project said, “At such high temperatures, silicon intensely shines in the same way that the Sun does, thus photovoltaic cells, thermophotovoltaic cells in this case, can be used to convert this incandescent radiation into electricity. The use of thermophotovoltaic cells is key in this system, since any other type of generator would hardly work at extreme temperatures.”
In addition, these cells can produce 100 times more electric power per unit area than conventional solar cells. These thermophotovoltaic cells are able to reach higher conversion efficiencies, even over 50 percent.
The final result is an extremely compact system with no mobile parts, silent and able to store up to 10 times more of energy than existing solutions using abundant and inexpensive materials.
The first application of these devices is expected to be in the solar thermal energy sector, thus avoiding the complex systems that use heat transfer fluids, valves and turbines to produce electricity. By simplifying the setting, the energy costs generated could dramatically reduce, and along with a higher storage capacity can turn this solution into a profitable solution system and an appropriate alternative of renewable generation.
These systems could be also used to storage electricity in the housing sector and to manage all energy needs (electricity and heating) in urban areas at medium and long term.
The team of UPM researchers has recently been granted funds through the EXPLORA project from Ministry of Economy and Competitiveness. Now, they are starting to manufacture the first lab-scale prototype.
Paralleling the research the team has started the business project SILSTORE that aims to industrialize these results. The project has been recognized as one of the best startups born in 2015 at UPM.
It is a kind of surprise to think of using what is essentially glass to store heat. But then glass has some interesting qualities readily observed. Its stable and very much non-reactive. Its dense and holds a lot of heat. It also gains heat slowly and releases it slowly. These attributes makes one wonder why its so late to the heat storage game. Might be because such a system will need pretty high temps to get going. But that’s a good thing and solar collection is getting there for supplying the heat quickly.