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Showing posts with label Energy. Show all posts
Showing posts with label Energy. Show all posts

Friday, 24 January 2020

New UV-C laser diode promises to disinfect your various health conditions

Structure and prototype of the UV-C laser diode. [Image: Asahi Kasei Corp / Nagoya University]


Japanese researchers made a laser diode that emits the shortest wavelength ultraviolet light ever achieved, covering an area of ​​applications that until now has not benefited from lasers.

These new devices could be used for health disinfection, treatment of skin diseases, such as psoriasis, and gas and DNA analysis.

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"Our laser diode emits the shortest wavelength in the world, at 271.8 nanometers (nm), under injection of alternating [electrical] current at room temperature," announced Professor Chiaki Sasaoka, from Nagoya University.

Previous efforts in the development of ultraviolet laser diodes have only managed to achieve emissions up to 336 nm, explains Sasaoka, not reaching the short-wavelength ultraviolet, or UV-C, which is in the range between 200 and 280 nm.


Material quality

To overcome the various problems that had been preventing the manufacture of this UV-C diode, the team used a high quality aluminum nitride (AlN) substrate as a basis to form the layers of the laser diode. The quality of the material was essential, since the lower quality AlN contains a large number of defects, which end up affecting the efficiency of the active layer of the laser diode in converting electrical energy into light energy.

In a laser diode the ‘p-type’ and ‘n-type’ layers are separated by a ‘quantum well’. When an electric current is passed through a laser diode, positively charged openings in the p-type layer and negatively charged electrons in the n-type flow flow to the center to connect, energy in the form of light particles called photons, is released.

The researchers designed quantum so well that it emitted deep UV light. P and N type layers consist of aluminum gallium nitride (AlGaN). The cladding layer, also made of AlGaN, is arranged on both sides of the p and n layers. The layer below the n-type layer contains silicon impurities, a process called doping. Doping is used as a technique to change material properties.

The layer above the p-type layer is subject to distributed polarization doping which touches the layer without adding impurity.

The aluminum content of the p-side layer is designed so that it is highest at the bottom and reduced at the top. The researchers believe that this aluminum gradient increases the flow of positively charged openings. Finally, a top contact layer was added, which consisted of p-type AlGaN magnesium alloy.



The researchers found that the doping of polarization - insertion of elements to change the behavior of the material - of the coating layer on the positive side ensured operation with a "remarkably low operating voltage" of 13.8V, and the emission "of the shortest length of wave reported so far ".

Asahi Kasei Corporation has already taken an interest in the project, and will help researchers develop deep UV lasers to come up with a commercial product.


Bibliography:

Article: A 271.8 nm deep-ultraviolet laser diode for room temperature operation

Authors: Ziyi Zhang, Maki Kushimoto, Tadayoshi Sakai, Naoharu Sugiyama, Leo J. Schowalter, Chiaki Sasaoka, Hiroshi Amano

Magazine: Applied Physics Express

DOI: 10.7567 / 1882 -0786 / ab50e0

Saturday, 14 December 2019

Scientists discovered cheaper way to make hydrogen from water


Researchers have discovered a cheaper way to make hydrogen from water: a team of scientists led by the UNSW has demonstrated a sustainable way to get hydrogen, which is necessary, among other things, for fueling vehicles hydrogen.

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Scientists from UNSW Sydney, Griffith University and Swinburne University of Technology have demonstrated that the capture of hydrogen by separating it from oxygen in water can be done using low-metals cost like iron and nickel (as catalysts), which speeds up the chemical reaction, while requiring less energy.

It should be noted that iron and nickel, which are found in abundance on Earth, would replace ruthenium, platinum and iridium, precious metals which until now have been considered as reference catalysts in the process of "Water fractionation".



Professor Chuan Zhao, of the UNSW School of Chemistry, explains that in water fractionation, two electrodes apply an electrical charge to the water, which allows the hydrogen to be separated from the water. 'oxygen. It can then be used as an energy carrier in a fuel cell.

“ What we do is coat the electrodes with our catalyst to reduce energy consumption. On this catalyst, there is a tiny nanoscale interface where iron and nickel meet at the atomic level, which then becomes an active site for water separation: this is where hydrogen can be separated from oxygen and captured as fuel, and oxygen can be released as environmentally friendly waste,” he explains.

Iron and nickel, but on a nanometric scale

Already in 2015, Professor Zhao's team invented a nickel-iron electrode for generating oxygen with unprecedented efficiency. However, Zhao believes that iron and nickel alone are not good enough catalysts for the generation of hydrogen, but that it is when they meet on the nanometric scale that the “magic operates ".

Nanoparticle design and electron microscopies. a Schematic representation of the Ni and Fe nanoparticles and the Ni-Fe Janus nanoparticles synthesis through the oleate-assisted micelle formation and the illustration on the HER across the Ni-γ-Fe2O3 interface in alkaline medium. b STEM-HAADF image of a single Ni–Fe NP nanoparticle and its corresponding EDS line-scan spectrum (scale bar: 1 nm). c High-resolution EDS mapping on STEM-HAADF images of the nanoparticles for Ni and Fe, selected area electron diffraction inset (image scale bars: 20 nm; SAED scale bar: 2 nm−1).


The nanoscale interface fundamentally changes the properties of these materials. Our results show that the nickel-iron catalyst can be as active as platinum in the generation of hydrogen,  ”he explains. "  An added benefit is that our nickel-iron electrode can catalyze both hydrogen and oxygen generation, so not only could we reduce production costs by using elements that are abundant on Earth, but also allow the use of one catalyst instead of two . ”

And indeed: a quick glance at current metal prices clearly demonstrates why this could be the change needed to accelerate the transition to the so-called hydrogen economy. Iron and nickel are priced at € 0.12 and € 19.65 per kilogram respectively. On the other hand, ruthenium, platinum and iridium are priced at € 10.6, € 37.9 and € 62.6 per gram respectively. In other words, thousands of times more expensive.



“ Right now, in our fossil fuel economy, we have this great incentive to move to a hydrogen economy so that we can use hydrogen as a clean and abundant energy carrier on Earth. Many people have been talking about the hydrogen economy for ages, but this time it seems like it really does happen  , "said Professor Zhao.

According to him, if water separation technology is developed, there could one day be hydrogen refueling stations (just like the service stations we know today), where we could refuel our hydrogen vehicles with hydrogen produced by this water division reaction. This could be done in a few minutes, compared to recharging hours in the case of electric cars with lithium battery.


Bibliography:

Overall electrochemical splitting of water at the heterogeneous interface of nickel and iron oxide
Bryan H. R. Suryanto, Yun Wang, Rosalie K. Hocking, William Adamson & Chuan Zhao

Nature Communications volume 10, Article number: 5599

http://dx.doi.org/10.1038/s41467-019-13415-8

Thursday, 12 December 2019

New study: Energy can be stored in the mountains using sand

Energy can be stored as sand or water for as long as needed.

Store energy in the mountains

Storing energy for long periods of time is one of the biggest challenges for a permanent move to a renewable and environmentally friendly energy matrix.

Solar energy, wind energy, wave energy, tidal energy and others are widely available, but they cannot maintain a constant supply of energy needed to meet the continuing demand of society.

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Julian Hunt and colleagues from Austria, Denmark and Italy believe they have come up with a suitable solution for situations where current alternatives do not apply - such as underwater hydropower , flow batteries and various ways of " storing the wind ", for example. .

The concept was named MGES for "mountain gravity energy storage" - and can be combined with a hydroelectric dam.


Generate electricity with sand

MGES consists of placing cranes on the edge of a steep mountain with sufficient reach to carry sand (or gravel) from a base storage to a mountain top storage location. An engine / generator moves sand-filled storage containers from the bottom up, similar to a cable car.

During this process, the potential energy is stored. Electricity is generated by lowering the sand from the upper storage location back to the base, harnessing the energy of the descending containers like a zip line.

If there are streams in the mountain, the MGES system can be hybridized with hydropower, where water would be used to fill storage containers in periods of high availability rather than sand or gravel, generating power.

MGES systems have the benefit that water can be added at any time in the system, thus increasing the possibility of capturing water from different heights on the mountain, which is not possible with conventional hydroelectric dams.

The nuclear fusion continues in a very distant future, so there are those who still bet on cold fusion

Sand does not evaporate

"One of the benefits [of the MGES system] is that sand is cheap and, unlike water, doesn't evaporate - so you never lose potential energy, and it can be reused countless times. That makes it particularly interesting for dry regions.

"In addition, hydroelectric plants are limited to a height difference of 1,200 meters due to very high hydraulic pressures. MGES plants can have height differences of more than 5,000 meters.

"Regions with high mountains, for example the Himalayas, Alps and Rockies, could therefore become important long-term energy storage centers. Other interesting places for MGES are islands such as Hawaii, Cape Verde, Madeira and the Isles. Pacific, with steep mountain terrain, "detailed Hunt.

To test the concept, the team proposed a future energy matrix for Molokai Island in Hawaii, using only wind , solar , batteries and MGES to meet the island's energy demand.

Although designed to store electricity on a large scale, liquid batteries are being tested in electric cars

Store energy

Hunt emphasizes that MGES technology is not suitable for meeting peak demand or storing energy in daily cycles; Its main advantage is to fill a gap in the market as a long term energy storage location.

MGES systems could, for example, store energy continuously for months and then generate electricity continuously for months or when water is available for hydropower, while batteries would handle daily storage cycles.



"It's important to note that MGES technology does not replace current energy storage options, but opens up new ways to store energy and harness untapped water potential in high mountain regions," said Hunt.




Bibliography:

Article: Mountain Gravity Energy Storage: A new solution for closing the gap between existing short- and long-term storage technologies

Authors: Julian David Hunt, Behnam Zakeri, Giacomo Falchett, Andreas Nascimento, Yoshihide Wada, Keywan Riahi

Journal: Nature Energy

DOI: 10.1016 / j.energy.2019.116419

Saturday, 23 November 2019

First superconducting wind generator successfully tested

The superconducting generator is smaller and lighter than the equivalent of permanent magnets

Superconducting Wind Generator

A superconducting wind generator was successfully tested for the first time on an active, full-scale turbine.

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The 3.6 megawatt superconducting generator is designed, developed and manufactured by the European consortium EcoSwing, and field tested in Thyboron, Denmark.

"The size of wind turbines has increased significantly in recent decades. However, current technology has been having trouble keeping up with the trend of increasing levels of energy per unit," said Anne Bergen of the University of Twente in the Netherlands. Low.

To meet this challenge, the team built a “high temperature” (-196 ° C) barium oxide ( ReBCO ) superconducting wired generator , one of the rare earth family members.

This option required fewer rare earth materials than permanent magnet wind generators - also built with materials from the same family - resulting in a lower cost. The superconducting can also carry high current densities, resulting in denser in coil power and a smaller weight.

The union of universities and companies in the project allowed technology to be transferred from laboratories to industry

From lab to factory

"The generator field test was extremely successful. When the generator was installed at Thyboron, the turbine reached its desired power range, including over 650 hours of grid operation. This shows the compatibility of the superconducting generator technology with all elements of an operating environment such as variable speeds, grid failures, electromagnetic harmonics and vibrations, "said Bergen.

But the advances were not limited to the technical part of the generator.

"He demonstrated that the production of high temperature superconducting coils is not limited to specialized laboratories, but constitutes a successful technology transfer from science to industry. The high temperature superconducting rotor has also been assembled in an industrial environment, showing that Superconducting components can be deployed in a standard manufacturing environment.

"Now that the concept has been proven, we expect superconducting generator technology to begin to be widely applied to wind turbines ," added Bergen.


Bibliography:

Article: Design and in-field testing of the world's first ReBCO rotor for a 3.6 MW wind generator

Authors: Anne Bergen, Rasmus Andersen, Markus Bauer, Hermann Boy, Marcel ter Brake, Patrick Brutsaert, Carsten Bührer, Marc Dhallé, Jesper Hansen, Herman ten Kate, Jürgen Kellers, Jens Krause, Erik Krooshoop, Christian Kruse, Hans Kylling, Martin Pilas, Hendrik Pütz, Anders Rebsdorf, Michael Reckhard, Eric Seitz, Helmut Springer, Nir Tzabar, Sander Wessel, Jan Wiezoreck , Tiemo Winkler, Konstantin Yagotyntsev

Magazine: Superconductor Science and Technology

Vol .: 32, Number 12

DOI: 10.1088 / 1361-6668 / ab48d6

Monday, 4 November 2019

Listen to the energy of lightning

Everyone knows that counting the seconds between the appearance of a lightning and the arrival of thunder gives the distance at which the lightning falls. Researchers at the Jean Le Rond Institute in Alembert and CEA have shown that this sound can also be used to estimate the energy of a lightning bolt. In this work published in Geophysical Research Letters , scientists deduce the geometry of lightning through a network of microphones, then calculate the energy.

© Institut Jean le Rond d'Alembert The acoustic energy of thunder as a function of the observation distance in km at the point of impact on the ground of the lightning. Squares represent simulated flashes and triangles measure HyMeX. Both follow a similar behavior.


Lightning rebalances the electrostatic charge between two clouds, or between a cloud and the ground. This electrostatic discharge locally increases the temperature of several tens of thousands of degrees, causing a shock wave that spreads in the atmosphere : thunder. If we know how to use this sound to estimate the distance at which a lightning struck, researchers at the Jean-Rond d'Alembert Institute (CNRS / Sorbonne University) and the CEA managed to use it to measure the distance power of lightning. A parameter that suffers from an uncertainty of up to three orders of magnitude.

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The team used the data measured in 2012 as part of the European project HyMeX, which studies the Mediterranean climate . Four microphones recorded for two months , and continuously, the sound emanating from the sky of the Cevennes, a region particularly struck by the storms. These recordings were first used to reconstruct the geometry of lightning, proving the correlation between the location of acoustic and electromagnetic sources. Then, the researchers used them again to isolate, within the thunder, the signalacoustics from some of its branches, including the main channel that connects the storm cloud and the ground. Now we can calculate the thunder of a flash from its geometry and its energy. The researchers compared field-collected thunders to a simulated thunderstorm database of 72 virtual flashes, statistically consistent with true lightning. This has shown that acoustic measurements give very good results in estimating the energy of negative-lightning flashes, which represent 90% of the cloud-to-cloud discharges, and at a distance of between three and twelve kilometers from the pickups.


Source

Wednesday, 30 October 2019

A new device captures CO2 from the air, stores it and returns it on demand


With the growth of human industrial activities, the rate of atmospheric carbon dioxide has increased considerably. In recent years, various methods for capturing CO2 in the air and transforming it into useful products have been developed with more or less efficiency. Recently, a team of MIT researchers developed a device to capture CO2 in the air at any concentration, store it, and redistribute it for practical uses such as CO2 injection for agriculture. or the gasification of beverages.

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A new way to remove carbon dioxide from the air could be an important tool in the fight against climate change. The system can operate at virtually any level of concentration, even at the roughly 400 parts per million currently in the atmosphere.

Most methods of removing carbon dioxide from a gas stream require higher concentrations, such as those present in flue gas emissions from fossil fuel plants. Some variants have been developed that can work with the low concentrations found in the air, but the new method consumes much less energy and costs less.

A "battery" to capture and release CO2 on demand

The technique, based on the passage of air through a stack of charged electrochemical plates, is described in the journal Energy and Environmental Science . The device is essentially a large specialized battery that absorbs carbon dioxide from the air (or other gas stream) passing on its electrodes during its charging, then releases the gas during its discharge.

In operation, the device would simply alternate between loading and unloading, with fresh air or feed gas being blown into the system during the loading cycle, and then the pure and concentrated carbon dioxide being expelled during unloading.

As the battery charges, an electrochemical reaction takes place on the surface of each electrode stack. These are covered with a compound called polyanthraquinone, composed of carbon nanotubes.

In this scheme of the new system, the air entering the top right passes into one of the two chambers (gray rectangular structures) containing battery electrodes that attract carbon dioxide. Then, the air flow passes into the other chamber, while the carbon dioxide accumulated in the first chamber is sent to a separate storage tank (right). These alternative flows allow a continuous operation of the process in two stages. Credits: Sahag Voskian / T. Alan Hatton


Electrodes have a natural affinity for carbon dioxide and readily react with its molecules in the airflow or feed gas, even when present at very low concentrations. The reverse reaction occurs when the battery is discharged - at this point, the device can provide some of the power needed for the entire system - and thus ejects a pure carbon dioxide stream. The entire system operates at ambient temperature and at normal atmospheric pressure.

Electrodes optimized to capture CO2 at any concentration

" The biggest advantage of this technology over most other carbon capture or absorption technologies is the binary nature of the adsorbent's affinity for carbon dioxide, " explains Voskian. In other words, the electrode material, by its nature, " has a high affinity or no affinity ", depending on the state of charge or discharge of the battery. Other reactions used for carbon capture require intermediate stages of chemical treatment or the provision of substantial energy such as heat or pressure differences.

Diagram of a unique electro-swing adsorption electrochemical cell, with porous electrodes and electrolyte separators. The outer electrodes, coated with a poly-1,4-anthraquinone composite, can capture CO2 when applying a reducing potential via the carboxylation of the quinone and release the CO2 during the polarity reversal. . Credits: Sahag Voskian / T. Alan Hatton

This binary affinity captures carbon dioxide in any concentration, including 400 parts per million, and releases it into any carrier stream, including 100% CO2, " says Voskian. That is, with any gas passing through the stack of these flat electrochemical cells, the captured carbon dioxide will also be ejected during the discharge. For example, if the desired end product is pure carbon dioxide for use in the carbonation of beverages, a stream of pure gas may be blown through the plates. The captured gas is then released from the plates and joins the stream.

A replacement for fossil fuels currently used to generate CO2

In some non-alcoholic beverage bottling plants, fossil fuels are burned to generate the carbon dioxide needed to make beverages. Similarly, some farmers burn natural gas to produce carbon dioxide to grow their crops in greenhouses. The new system could eliminate this need for fossil fuels in these applications and, at the same time, eliminate greenhouse gases from the air.

Alternatively, the flow of pure carbon dioxide could be compressed and injected underground for long-term disposal, or even converted into fuel through a series of chemical and electrochemical processes. " All of this is done under ambient conditions - no thermal, chemical or pressurized input is needed. It's just these very thin sheets, with both active surfaces, that can be stacked in a box and connected to a power source . "

The new device can be used in many fields requiring the generation and injection of carbon dioxide, replacing fossil fuels. Credits: Sahag Voskian / T. Alan Hatton


We have been striving to develop new technologies to solve a range of environmental problems, avoiding the use of thermal energy sources, changing the system pressure, or adding chemicals to complete the separation cycles. of liberation. This carbon dioxide capture technology is a clear demonstration of the power of electrochemical approaches that require only small voltage variations to drive separations, "says Hatton.

In a working installation, for example in a power plant producing continuous exhaust gas, two sets of cells of this type of electrochemical cells could be mounted side by side to operate in parallel, the combustion gases being directed from first to a first set for carbon capture, then diverted to the second set while the first set enters its discharge cycle.

An efficient, inexpensive method with low energy consumption

By alternating, the system can still capture and evacuate the gas. In the laboratory, the team proved that the system could withstand at least 7000 charge-discharge cycles, with a loss of efficiency of 30% during this period. Researchers estimate that they can easily improve this figure between 20,000 and 50,000 cycles.

The electrodes themselves can be made with standard chemical treatment methods. Although this is done today in a laboratory, they can be adapted so that they can finally be manufactured in large quantities through a roll-to-roll process, similar to a newspaper printing press. " We've developed very cost-effective techniques, " Voskian says, arguing that they could be produced for tens of dollars per square meter of electrode.

Compared to other existing carbon capture technologies, this system consumes little, as it only requires about one gigajoule of energy per tonne of carbon dioxide captured. Other existing methods have energy consumption ranging from 1 to 10 gigajoules per tonne, depending on the input carbon dioxide concentration.

Source

Monday, 29 July 2019

A new device channeling heat into light could bring solar cell efficiency up to 80%!

Gao et al. ACS Photonics, 2019 

Solar cells, or photovoltaic cells, which "turn" sunlight into electricity, are a brilliant element of modern technology. However, one particular aspect has proved to be an important problem: they are not very effective. Indeed, the majority of sunlight absorbed is lost, in the form of heat. As a result, the average efficiency of a commercial solar panel is between 11 and 22% only. But now, a new device could increase this figure up to 80%, which would be absolutely revolutionary.


This new design is based on a set of single-walled carbon nanotubes, which recaptures "thermal" photons from the infrared radiation (heat) lost from solar panels. Then, the device emits this energy in the form of light in a different wavelength, which can in turn be recycled into electricity.

Thermal photons are just photons emitted by a hot body ," said Junichiro Kono of Rice University. " If you look at something hot with an infrared camera, you will see it shine. The camera captures exactly those thermally excited photons , "Kono added.

It should be known that infrared radiation is the part of the sunlight that carries heat. Of course, this is invisible to the human eye, but is on the same electromagnetic spectrum as visible light, radio waves, and X-rays.

This type of infrared radiation is emitted by your stove, by a campfire or even by your cat purring on your lap. In other words, basically, anything that emits heat emits radiation. " The problem is that the thermal radiation is broadband, while the conversion of light into electricity is only effective if the emission is narrowband. The challenge was to bring broadband photons into a narrow band , "said engineer Gururaj Naik.

One of the properties of nanotubes is that the electrons in them can only move in one direction. This produces an effect known as hyperbolic dispersion, in which the films are metal conductors (in one direction), but insulate perpendicular to that direction.

This means that thermal photons can enter from (almost) anywhere, but they can only escape in one direction. This process converts heat into light and from there it can be converted into electricity.

In the device created by the researchers, the carbon nanotube film can withstand temperatures up to 700 degrees Celsius, although the base material is able to withstand a much higher temperature, up to 1600 degrees Celsius.

  Then, the research team exposed their device to a heat source to confirm the narrowband output. Each of the resonator cavities in the film reduced the thermal photon band, producing light. The next research step will therefore be to collect this light using photovoltaic solar cells and to confirm the predicted efficiency.

Xinwe Li, a graduate student from Rice University (left), and Weilu Gao, postdoctoral researcher. Gao contributed to the development of a device to recycle heat lost in photovoltaic cells. This could ultimately improve the efficiency of industrial waste heat recovery. Credits: Jeff Fitlow.

By compressing all the thermal energy wasted in a small spectral region, we can transform it into electricity very efficiently. The theoretical prediction is that we can achieve efficiency up to 80%! Naik said.


Bibliography:

Macroscopically Aligned Carbon Nanotubes as a Refractory Platform for Hyperbolic Thermal Emitters
Weilu GaoChloe F. DoironXinwei LiJunichiro KonoGururaj V. Naik*
ACS Photonics2019671602-1609
https://doi.org/10.1021/acsphotonics.9b00452


Saturday, 20 July 2019

Trapping CO2 in natural "molecular cages" to produce electricity

Methane in flames at the end of a methane hydrate

In view of the tremendous increase in atmospheric CO2 levels, scientists have embarked on a race to effectively reduce the concentration of this greenhouse gas. Several techniques have been proposed in recent years, but all have proved relatively expensive and without any real counterpart. Recently, researchers have proposed a method to trap CO2 in methane hydrates; the methane thus hunted could be burned to produce electricity in return.


A method explored over the last decade could be a step forward, according to a new computer simulation. The process would involve pumping atmospheric CO2 into methane hydrates - large pools of chilled water and methane under the sea floor, under water at a depth of 500 to 1000 meters - where the gas would be stored or sequestered Permanently.

Inbound CO2 would release methane, which would be channeled to the surface and burned to produce electricity. This would fuel the sequestration operation or generate income to pay for it. There are many deposits of methane hydrate along the coast of the Gulf of Mexico and other coasts. Large power plants and CO2-emitting industrial facilities also border the Gulf Coast.

Methane hydrates form naturally at the bottom of the seas and oceans. They constitute cages trapping methane molecules escaping from geological cracks. Credits: Janet Kimantas

An option would be to capture the gas directly from the nearby chimneys, preventing it from reaching the atmosphere. And factories and industries themselves could provide a direct market for the electricity produced.

Trapping atmospheric CO2 in methane hydrates

A methane hydrate is a deposit of frozen water molecules, similar to a crystal lattice. The unstable network includes many empty molecular-size pores, or "cages," that can trap methane molecules rising through cracks in the rock below. The computer simulation shows that the extraction of methane with CO2 is greatly improved if a high concentration of nitrogen is also injected and the gas exchange is a two-step process.

In one step, the nitrogen enters the cages; this destabilizes the imprisoned methane, which escapes from the latter. In a separate step, nitrogen helps CO2 to crystallize in empty cages. The disturbed system " seeks to reach a new equilibrium; the balance goes to more CO2 and less methane e "explains Kris Darnell, lead author of the study published in the journal Water Resources Research.

A methane hydrate forms a real molecular cage that can trap several types of gas. The method proposed by the researchers aims to drive the methane out of the cage and replace it with CO2; the methane is then burned out to produce electricity. Credits: AMU

A group of laboratories, universities and companies tested the technique in a limited 2012 feasibility test on the North Slope of Alaska, where methane hydrates are formed in sandstone under deep permafrost. They sent CO2 and nitrogen through a pipe in the hydrate. Part of the CO2 was eventually stored and methane was released in the same pipe. " It's good that Kris Darnell can make progress, " says Ray Boswell of the US Department of Energy's National Energy Technology Laboratory.

Brine: an alternative to methane hydrates

The new simulation also showed that CO2 exchange for methane would probably be much larger and faster if CO2 penetrated at one end of a hydrate pool and methane was collected at a far end. . The concept of the technique is quite similar to that of Steven Bryant and other researchers at the University of Texas, presented in the early 2010s.

In addition to numerous deposits of methane hydrates, the Gulf Coast includes large pools of warm salt brine in sedimentary rocks beneath the coast. In this system, the pumps would send CO2 down through one end of the deposit, forcing the brine into a pipe at the other end and rising to the surface. There, the hot brine would circulate in a heat exchanger, where the heat could be extracted and used for industrial processes or to generate electricity.

The upstream brine also contains methane that could be siphoned and burned. CO2 dissolves in the underground brine, becomes dense and flows further underground, where it remains theoretically trapped.

Interesting methods still too economically unviable 


Both systems face great practical challenges. A concentrated flow of CO2 is created; gas represents only 0.04% of air and about 10% of stack emissions from a power plant or industrial plant. If an efficient system using methane hydrate or brine requires a 90% CO2 input, for example, the gas concentration will require a huge amount of energy, which makes the process very expensive. " But if you only need a 50% concentration, it could be more interesting, " says Bryant. " You have to reduce the cost of capturing CO2 ".

Another major challenge for the methane hydrate approach is to collect released methane, which could simply escape the deposit through numerous cracks, and in all directions.

Given these realities, there is little economic incentive to use methane hydrates to sequester CO2. But with increasing atmospheric concentrations and global warming, systems capable of capturing gas while providing the energy or revenue needed to run it could become more viable than techniques that simply extract CO2. from the air and trap him without offering anything in return.



Saturday, 6 July 2019

Bacteria and graphene to produce clean energy



If the development of technologies to produce or store clean energy has long rested on law materials, since a few years scientists are investigating methods to combine micro-organisms and materials, in the aim to achieve clean energy. Recently, a team of researchers combined an electricity generating bacteria and oxide Graphene to a get a material biohybride whose energy applications are extremely broad.


Combine with carbon nanomaterials microorganisms could facilitate the transition to renewable energy. Researchers at the KAUST (King Abdullah University of Science and Technology) show that the bacteria and nanomaterials can be used together to form a biohybride material that works well as electrocatalyseur. The material could be used in the production of free carbon to solar fuels and in many other applications of green energy.

A process called response to evolution of oxygen (REL) is at the heart of many clean energy technology. In the case of solar fuel production, for example, OER can use solar electricity to split water into oxygen and hydrogen molecules, thereby producing clean hydrogen that can be used as fuel. Currently, rare and expensive metals are used as electrocatalysts REL.

Bacteria and graphene oxide: a green biohybride material

But biohybrides graphene-based materials could be an inexpensive and eco-friendly alternative, showed Pascal Saikaly and his team. Reduced graphene oxide and graphene are highly conductive, rugged mechanical and widely available. However, they become active catalysts only after having been doped with other elements, such as sulfur, iron, nitrogen, or copper.

The Geobacter sulfurreducens proteobacterie observed with the scanning electron microscope; It generates electricity by reducing the carbon compounds. She is so alone, a source of bio-energy. Credits: Reema Bansal et al. 2015


REL graphene-based catalysts are usually developed by chemical, methods that require conditions of stringent reaction obtained with abundant toxic chemicals and high temperature " explains Shafeer Kalathil, author of the study. A more environmentally friendly alternative is to use bacteria to occupy the surface of reduced graphene oxide. " We used the electric sulfurnucens Geobacter bacteria because it is not pathogenic, rich in the iron-containing proteins and present in abundance in nature ."

A highly effective Bionic electrocatalyseur

When the team mixed the bacteria and graphene oxide in oxygen-free conditions, bacterial cells adhered to the surface and produced iron-rich proteins that interacted with graphene oxide biochemically in the as part of their natural metabolism.

As a result, reduced graphene oxide will eventually be combined with iron, copper and sulfur; becoming a highly effective REL electrocatalyseur. The details have been published in the journal Chemistry of Materials.

The information supplied by the bacteria have transformed catalytically inert graphene in a highly used catalyst. ' OER materials biohybrides activity was greater than expensive catalysts for OER metal "said Kalathil. The bonus is the ecological method used by the team to make it happen.

Saikaly and his team are now working on the production and marketing large scale of this biohybride catalyst. They also develop other types of catalysts biohybrides for other important electro-catalytiques reactions, such as the hydrogen evolution reaction and the reduction of carbon dioxide.




Bibliography:

Bioinspired Synthesis of Reduced Graphene Oxide-Wrapped Geobacter sulfurreducens as a Hybrid Electrocatalyst for Efficient Oxygen Evolution Reaction
Chem. Mater.201931103686-3693
https://doi.org/10.1021/acs.chemmater.9b00394

Monday, 1 July 2019

Artificial electric eel generates energy even underwater

The bionic nanogenerator is extremely simple, but works in any environmental condition. [Image: TAN Puchuan]

Bionic nanogenerator:

Chinese researchers have developed a bionic nanogenerator inspired by electric eels.

Yang Zou and his colleagues say their new technology meets the rigid demands of portable and dressing equipment in terms of stretchability, deformability, biocompatibility and impermeability.

They point out as key applications the creation of a power source for electronic devices that need to operate in the air, earth or water, and in human monitoring, due to their excellent flexibility and mechanical responsiveness.

The nanogenerator mimics the structure of the ionic channels in the citomembrane of the electric eel electrocytes.

The mechanically sensitive bionic channel was created based on the incompatibility of voltage between the polymers PDMS ( polydimethylsiloxane ) and silicone.

The demonstration involved monitoring a swimmer's movements in real time. [Image: TAN Puchuan]

Artificial eel

Like the ion channel of the eels, the nanogenerator can generate an open circuit voltage of up to 10 V underwater and up to 170 V under dry conditions.

This capability was maintained after 50,000 uniaxial tensile tests with a 50% traction rate.

To prove the practicality of the technology, the researchers built an underwater wireless motion monitoring system. Through this system, signals from different swimming movements can be transmitted, displayed and recorded synchronously.



Bibliography:

 The bionic stretchable nanogenerator for underwater sensing and energy harvesting
Yang Zou, Puchuan Tan, Bojing Shi, Han Ouyang, Dongjie Jiang, Zhuo Liu, Hu Li, Min Yu, Chan Wang Xuecheng Qu, Luming Zhao Yubo Fan, Zhong Lin Wang, Zhou Li
 Nature Communications Vol .: 10,
Article number: 2695 
DOI: 10.1038 / s41467-019-10433-4

Friday, 28 June 2019

Researchers have discovered the new property of Light: the autotorque

Like a screw with a heterogeneous thread, the light with autotorque will have immediate technological applications. [Image: Rego et al. - 10.1126 / science.aaw9486]

Twisted light

Spanish researchers have discovered that light has a new property, which they named autotorque.

This discovery opens up exciting possibilities in light-related applications, from consumer appliances to scientific equipment and fiber-optic telecommunications.

In addition to the many known properties - such as intensity and wavelength - the light can be twisted , possessing what is known as angular momentum - the photons travel in a straight line, but spinning around the axis of the beam of light.

Light beams carrying highly structured angular momentum, known as angular orbital momentum (OAM), are known as vortex bundles.

The intensity of these beams, which have a ring-like shape, has applications in optical communications, microscopy, quantum optics and microparticle manipulation.

Vision of longitudinal section of light beam with autotorque. [Image: Rego et al. - 10.1126 / science.aaw9486]

Light with autotorque

Knowing this turn of twisted light, Laura Rego and colleagues at the University of Salamanca wondered if this spin of the photons could not function in a time-dependent way.

It can, and this is precisely what the autotorque consists of: Light beams with their own torque have an angular momentum that changes continuously in time. In other words, light not only twists, but has a different degree of twisting along the length of the beam.

The bundles resemble a croissant, containing more than one octave of orbital angular momentum values ​​along the light pulse.

"This is the first time someone has predicted or even observed this new property of light," said Laura. "For example, we think that we can modulate the orbital angular momentum of light in the same way that frequency is modulated in communications."

If this is indeed possible, telecommunications will be able to jump-start, allowing much more data to be placed on the same optical fibers.

In addition, this new light mode opens new perspectives for optical tweezers , tiny tracers used to trap nanoparticles in cells.




Bibliography:

Generation of extreme-ultraviolet beams with time-varying orbital angular momentum

 Laura Rego, Kevin M. Dorney, Nathan J. Brooks, Quynh L. Nguyen, Chen-Ting Liao, Julio San Roman, David E. Couch, Allison Liu, Emilio Pisanty, Maciej Lewenstein, Luis Plaja, Henry C. Kapteyn, Margaret M. Murnane, Carlos Hernández-García

 Science DOI: 10.1126 / science.aaw9486

Thursday, 27 June 2019

Wireless charging can reduce cell phone battery life

The three modes tested: (a) charging plugged into the network; (b) aligned inductive loading and (c) misaligned inductive loading. [Image: Loveridge et al. - 10.1021 / acsenergylett.9b00663]

Inductive charging

The way you recharge your phone - from the standard charger, plugged in, or the inductive, wireless charging - can change the life expectancy of your battery.

This is the conclusion of Melanie Loveridge and colleagues at the University of Warwick in the UK who compared three modes of charging the cell phone, two of which involved charging wirelessly.

Inductive charging allows a power source to transmit electricity through an air gap , without the use of wiring.

The inclusion of inductive charging coils in several newer models of mobile phones has led to the rapid increase in adoption of the technology. In 2017, automakers announced the inclusion of consoles within 15 models to inductively charge consumer electronics devices, including cellphones - and on a much larger scale, several companies are considering charging electric vehicle batteries in the same way.

The problem is that this charging mode generates a lot of unwanted heat, which harms the battery, decreasing its life.

There are several sources of heat generation associated with any inductive charging system - both in the charger and in the apparatus being charged. This additional heating is aggravated by the fact that the apparatus and the charging base are in physical contact, which means that any heat generated in one of them is transferred to the other by simple conduction and thermal convection.

On cell phones, the coil that receives power is attached to the back cover of the phone, next to the battery and everything else, which limits the possibility of dissipating the heat generated inside the phone or to protect it from the heat coming from the outside.

The life of a battery is closely related to the temperature at which it operates. The higher the temperature, the smaller the number of cycles in which it can be charged and used. 

Batteries and temperature

The batteries of lithium ions are chemical devices, and a rule of thumb - or, more technically, the equation Arrhenuis - establishes that for most chemical reactions, the reaction rate doubles for every 10 ° C increase in temperature.

In a battery, undesired reactions that may occur include the accelerated growth rate of passive films (a fine inert coating rendering the underlying surface non-reactive) on the electrodes of the cell. This occurs through redox reactions, which irreversibly increase the cell's internal resistance, resulting in degradation in performance and, ultimately, failure.


An additional problem encountered by researchers occurs when the coil of the device being charged is not perfectly aligned with the coil of the charger - the results are even worse, with greater heat generation.

Although manufacturers warn of catastrophic failures - explosions, for example - at operating temperatures above 50 or 60 ° C, a lithium-ion battery with a temperature above 30 ° C is typically considered at elevated temperature, exposing the battery to the risk of a shorter life expectancy, say researchers.

So, although the team has not established how much battery life your cell phone will lose in each case - which would require long-term observations and a large number of handsets to establish an average - the message is quite clear: Cell phone heats up with inductive charging, and battery and high temperatures do not.

Alignment between the machine and charger coils is essential for greater wireless charging efficiency. [Image: Loveridge et al. - 10.1021 / acsenergylett.9b00663]

Charging and reducing battery life

In the case of the telephone charged with the charger plugged into the conventional mains, the maximum average temperature reached within 3 hours of charging did not exceed 27 ° C, starting from an ambient temperature of 25 ° C.

In contrast, with the phone being charged by aligned inductive charging, the temperature peaked at 30.5 ° C, which was gradually reduced during the second half of the charging period.

In the case of misaligned inductive loading, the peak temperature was of similar magnitude (30.5 ° C), but this temperature was reached earlier and persisted for much longer at this level (125 minutes, versus 55 minutes for correctly aligned loading) .

The maximum average temperature of the charging base during charging under misalignment reached 35.3 ° C, two degrees above the temperature detected when the phone was aligned, which reached 33 ° C. This signals the deterioration in system efficiency with additional generation of heat attributable to energy losses and parasitic currents.

Also noteworthy was the fact that the maximum input power at the charging base was higher in the test where the phone was misaligned (11W) than with the phone well aligned (9.5 W).

The team's conclusion is that the inductive charging, while convenient, will likely lead to a reduction in the battery life of the mobile phone. For many users, this degradation may be an acceptable price for convenience, but for those who wish to take advantage of the longer phone life, cable charging is still recommended.



Bibliography: 

Temperature Considerations for Charging Li-Ion Batteries: Mains versus Inductive Charging Modes for Portable Electronic Devices
Mel J. Loveridge, Chaou C. Tan, M. Faduma Maddar Guillaume Remy, Mike Abbott, Shaun Dixon, Richard McMahon Ollie Curnick, Mark Ellis, Mike Lain, Anup Barai, Mark Amor-Segan, Rohit Bhagat, Dave Greenwood
 ACS Energy Letters
 Vol .: 4, 5, 1086-1091
 DOI: 10.1021 / acsenergylett.9b00663

Monday, 24 June 2019

Transparent battery stores and generates energy

Scheme of the layers and photo of the prototype, which is flexible in addition to transparent. [Image: 10.1021 / acsami.8b20143]

Transparent rechargeable battery


Researchers from South Korea have created a fully transparent and flexible battery prototype.

More than that, they added a number of other features, composing an almost totally transparent device prototype.

Using a graphene film as an electrode and a "semi-solid" electrolyte, the battery achieves a level of transparency of 77.4%.

In addition, the team designed the structure with self-loading and storage functions. This was done by inserting a power storage panel - a supercapacitor - inside the top layer of the device, and a power conversion panel - a nanogenerator - inside the bottom layer.

That is, it is possible to charge the battery by tightening it or taking advantage of natural movements such as the floor, which makes the device suitable for dressing applications.

Finally, a touch-sensitive layer was placed just below the top-tier power storage panel, allowing you to create a transparent whole device.

"We decided to start this research because we were impressed with the transparent smartphones that appear in the movies.While there is still a long way to go because of high production costs, we will do our best to further this technology now that we have achieved this success in the field of transparent energy storage, "said Professor Changsoon Choi of Daegu Gyeongbuk Institute of Science and Technology (DGIST).



Bibliography:

 Single-Layer Graphene-Based Transparent and Flexible Multifunctional Electronics for Self-Charging Power and Touch-Sensing Systems
Sungwoo Chun, Wonkyeong Son, Gwangyeob Lee, Shi Hyeong Kim, Jong Woo Park, Seon Jeong Kim, Changhyun Pang, Changsoon Choi ACS
Applied Materials & Interfaces
 DOI: 10.1021 / acsami.8b20143

Friday, 21 June 2019

World's Strongest Magnetic Field Generated From A Tiny Magnet

The recorded electromagnet is the size of an empty roll of toilet paper. [Image: MagLab]

World's Strongest Magnet

Engineers at the US High Magnetic Fields Laboratory (MagLab) built the Earth's strongest magnet with a record 45.5 teslas magnetic density flux.

Unlike its gigantic predecessor, the 45T, which held the record for almost two decades, the new configuration is much smaller and uses much less energy.

This was possible with the use of wires of a rare earth compound called copper-barium oxide (REBCO), which becomes superconducting at -196 ° C. This cold end also allows the creation of coils without the need of insulation - the coil reaches 1,260 A / mm2.


The small record holder, however, is not yet a full-fledged working magnet because he was only able to sustain his magnetic field for a few seconds. But the experiment showed that magnets made of copper oxide superconductors are a viable option for longer-lasting versions - the most common is to use niobium.

And it's good news considering that its predecessor, the 45T, which is fully functional, is a monster 6.7 meters tall and 35 tons that consumes 30 MW of energy - it's 15,000 liters of water pumped per minute to keep it going, refrigerated it.

Details of the construction of the strongest electromagnet in the world. [Image: Hahn et al. - 10.1038 / s41586-019-1293-1]

"We are really opening a new door. This technology has very good potential to completely change the horizons of high field applications because of its compact nature," said Seungyong Hahn, a MagLab engineer. 






Bibliography:

 45.5-tesla direct-current magnetic field generated with a superconducting high-temperature magnet
SEUNGYONG Hahn, Kwanglok Kim, Kwangmin Kim, Hu Xinbo, Thomas Painter, Iain Dixon, Seokho Kim, Kabindra R. Bhattarai, So Noguchi, Jan Jaroszynski, David C. Larbalestier 
Nature
 DOI: 10.1038 / s41586-019-1293-1

Wednesday, 19 June 2019

Plastic Laser finally becomes reality

This is the first time that laser emission is achieved in plastic or organic diodes. [Image: COPER / Kyushu University]

Researchers from Japan have demonstrated that an organic semiconductor-based laser diode is indeed possible, paving the way for the expansion of lasers in applications such as biosensors, screens, medical devices and optical communications.

Atula Sandanayaka and her colleagues at Kyushu University claim to have convincingly demonstrated for the first time that organic semiconductor laser diodes have finally come true - earlier allegations of electrically induced laser generation using organic materials have proved to be false on several occasions with other phenomena being confused with the laser emission.

A critical step in the laser is to inject a large amount of electrical current into the organic layers to achieve a condition called population inversion. However, the high resistance to electricity of many organic materials makes it difficult to get enough electrical charges on the materials before they warm up and burn - the organic materials are polymers, or plastics.

In addition, losses inherent to most organic materials and operation under high currents reduce efficiency, further increasing the required current.

Laser emission


To overcome these obstacles, Sandanayaka used a highly efficient organic light emitting material with relatively low resistance to electricity and a low amount of losses - the material is known as BSBCz (4,4'-bis [(N-carbazole) ] biphenyl).

But finding the right stuff was not enough.

He also had to design a grid structure of insulation material on one of the electrodes to inject electricity into the thin organic films. These networks - called distributed feedback structures - were already known to be capable of producing the necessary optical effects for the laser.

"By optimizing such networks, we were able to not only obtain the desired optical properties but also control the flow of electricity in the devices and minimize the amount of electricity needed to observe the laser emission from the thin organic film," said Professor Chihaya Adachi.

Organic laser prototype scheme and photo. [Image: 10.7567 / 1882-0786 / ab1b90] 

Organic laser diode

For a long time considered a "holy grail" in the area of ​​light emitting components, organic laser diodes use carbon-based materials to emit light instead of inorganic semiconductors such as arsenide and gallium nitride used in commercial devices.

Organic lasers are in many ways similar to organic light emitting diodes (OLEDs), in which a thin layer of organic molecules emits light when electricity is applied. OLEDs have become the best choice for cell phone screens because of their high efficiency and vibrant colors, which can be easily altered by synthesizing new organic molecules.

It turns out that organic laser diodes produce much purer light, allowing additional applications, but require currents with magnitudes higher than those used in OLEDs to achieve coherent light emission. These extreme conditions caused the prototypes built so far to sink well before the laser could be observed.

Researchers are so confident in their new components that they founded a company to make the missing developments to create a commercial product and launch the organic laser diodes in the market.


References:

Indication of current-injection lasing from an organic semiconductor
Atula SD Sandanayaka, Toshinori Matsushima, Fatima Bencheikh, Shinobu Terakawa, William J. Potscavage Jr., Chuanjiang Qin, Takashi Fujihara, Kenichi Goushi, Jean-Charles Ribierre, Chihaya Adachi
Applied Physics Express
DOI: 10.7567 / 1882-0786 / ab1b90

Tuesday, 18 June 2019

Biobateria produces clean electricity for days

Simple, small and efficient, the biobattery is ideal for the "internet of disposable things". [Image: Sean Choi]

Bio-battery or bio-cell?

The microbial batteries have been around for some time, but the emergence of the Internet of things can make them return to the headlines.

The good news is that bio-battery technology is not at a standstill, which has made them cheaper and more efficient.

"This new technique, built in the form of a small, compact, disposable package, at a low price, can cheaply connect things to work for a programmed period and then be discarded promptly," said Professor Seokheun Choi of Binghamton University, United States.


In fact, the new biobattery is in the middle between a battery and a microbial fuel cell - a bio-hybrid battery would be a good name.

The team had already developed paper biobanks and full-fledged microbial fuel cells .

"The bio-mass we developed this time is a kind of combined technique of these two, the pot life was significantly increased using solid-state compartments, but the device is a form of battery without complicated energy-consuming fluid-feeding systems and what typical microbial fuel cells require, "said Choi.

In other words, the team managed to get rid of the more complex part of the system.

"We have revolutionized the liquid anolyte, the salt bridge and the cathode compartment in solid counterparts, increasing their densities and enabling their slow and continuous reactions. In addition, the solid phase components will make the device suitable for miniaturization, integration and operation with the internet applications of solid-state things, "wrote the team.

Hybrid microbattery produced a maximum power density of 4 μW / cm 2 (0.3 mW / cm 3) and a current density of 45 μA / cm 2 (0.37 mA / cm 3) after 96 hours of operation, while the earlier, more complex, liquid-based version stopped generating power after 4 hours.




Bibliography:

A solid phase bacterium -based biobattery for low-power, low-cost, internet of Disposable Things
Maedeh Mohammadifar, Seokheun Choi
Journal of Power Sources
Vol .: 429, Pages 105-110
DOI: 10.1016 / j.jpowsour.2019.05. 009