Category Archives: energy

Do you want that coffee with some graphene on toast?

These scientists are excited:

For those who prefer text, here’s the Rice University Feb. 13, 2018 news release (received via email and available online here and on EurekAlert here) Note: Links have been removed),

Rice University scientists who introduced laser-induced graphene (LIG) have enhanced their technique to produce what may become a new class of edible electronics.

The Rice lab of chemist James Tour, which once turned Girl Scout cookies into graphene, is investigating ways to write graphene patterns onto food and other materials to quickly embed conductive identification tags and sensors into the products themselves.

“This is not ink,” Tour said. “This is taking the material itself and converting it into graphene.”

The process is an extension of the Tour lab’s contention that anything with the proper carbon content can be turned into graphene. In recent years, the lab has developed and expanded upon its method to make graphene foam by using a commercial laser to transform the top layer of an inexpensive polymer film.

The foam consists of microscopic, cross-linked flakes of graphene, the two-dimensional form of carbon. LIG can be written into target materials in patterns and used as a supercapacitor, an electrocatalyst for fuel cells, radio-frequency identification (RFID) antennas and biological sensors, among other potential applications.

The new work reported in the American Chemical Society journal ACS Nano demonstrated that laser-induced graphene can be burned into paper, cardboard, cloth, coal and certain foods, even toast.

“Very often, we don’t see the advantage of something until we make it available,” Tour said. “Perhaps all food will have a tiny RFID tag that gives you information about where it’s been, how long it’s been stored, its country and city of origin and the path it took to get to your table.”

He said LIG tags could also be sensors that detect E. coli or other microorganisms on food. “They could light up and give you a signal that you don’t want to eat this,” Tour said. “All that could be placed not on a separate tag on the food, but on the food itself.”

Multiple laser passes with a defocused beam allowed the researchers to write LIG patterns into cloth, paper, potatoes, coconut shells and cork, as well as toast. (The bread is toasted first to “carbonize” the surface.) The process happens in air at ambient temperatures.

“In some cases, multiple lasing creates a two-step reaction,” Tour said. “First, the laser photothermally converts the target surface into amorphous carbon. Then on subsequent passes of the laser, the selective absorption of infrared light turns the amorphous carbon into LIG. We discovered that the wavelength clearly matters.”

The researchers turned to multiple lasing and defocusing when they discovered that simply turning up the laser’s power didn’t make better graphene on a coconut or other organic materials. But adjusting the process allowed them to make a micro supercapacitor in the shape of a Rice “R” on their twice-lased coconut skin.

Defocusing the laser sped the process for many materials as the wider beam allowed each spot on a target to be lased many times in a single raster scan. That also allowed for fine control over the product, Tour said. Defocusing allowed them to turn previously unsuitable polyetherimide into LIG.

“We also found we could take bread or paper or cloth and add fire retardant to them to promote the formation of amorphous carbon,” said Rice graduate student Yieu Chyan, co-lead author of the paper. “Now we’re able to take all these materials and convert them directly in air without requiring a controlled atmosphere box or more complicated methods.”

The common element of all the targeted materials appears to be lignin, Tour said. An earlier study relied on lignin, a complex organic polymer that forms rigid cell walls, as a carbon precursor to burn LIG in oven-dried wood. Cork, coconut shells and potato skins have even higher lignin content, which made it easier to convert them to graphene.

Tour said flexible, wearable electronics may be an early market for the technique. “This has applications to put conductive traces on clothing, whether you want to heat the clothing or add a sensor or conductive pattern,” he said.

Rice alumnus Ruquan Ye is co-lead author of the study. Co-authors are Rice graduate student Yilun Li and postdoctoral fellow Swatantra Pratap Singh and Professor Christopher Arnusch of Ben-Gurion University of the Negev, Israel. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of computer science and of materials science and nanoengineering at Rice.

The Air Force Office of Scientific Research supported the research.

Here’s a link to and a citation for the paper,

Laser-Induced Graphene by Multiple Lasing: Toward Electronics on Cloth, Paper, and Food by Yieu Chyan, Ruquan Ye†, Yilun Li, Swatantra Pratap Singh, Christopher J. Arnusch, and James M. Tour. ACS Nano DOI: 10.1021/acsnano.7b08539 Publication Date (Web): February 13, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.

h/t Feb. 13, 2018 news item on Nanowerk

The devil’s (i.e., luciferase) in the bioluminescent plant

The American Chemical Society (ACS) and the Massachusetts Institute of Technology (MIT) have both issued news releases about the latest in bioluminescence.The researchers tested their work on watercress, a vegetable that was viewed in almost sacred terms in my family; it was not easily available in Vancouver (Canada) when I was child.

My father would hunt down fresh watercress by checking out the Chinese grocery stores. He could spot the fresh stuff from across the street while driving at 30 miles or more per hour. Spotting it entailed an immediate hunt for parking (my father hated to pay so we might have go around the block a few times or more) and a dash out of the car to ensure that he got his watercress before anyone else spotted it. These days it’s much more easily available and, thankfully, my father has passed on so he won’t have to think about glowing watercress.

Getting back to bioluninescent vegetable research, the American Chemical Society’s Dec. 13, 2017 news release on EurekAlert (and as a Dec. 13, 2017 news item on ScienceDaily) makes the announcement,

The 2009 film “Avatar” created a lush imaginary world, illuminated by magical, glowing plants. Now researchers are starting to bring this spellbinding vision to life to help reduce our dependence on artificial lighting. They report in ACS’ journal Nano Letters a way to infuse plants with the luminescence of fireflies.

Nature has produced many bioluminescent organisms, however, plants are not among them. Most attempts so far to create glowing greenery — decorative tobacco plants in particular — have relied on introducing the genes of luminescent bacteria or fireflies through genetic engineering. But getting all the right components to the right locations within the plants has been a challenge. To gain better control over where light-generating ingredients end up, Michael S. Strano and colleagues recently created nanoparticles that travel to specific destinations within plants. Building on this work, the researchers wanted to take the next step and develop a “nanobionic,” glowing plant.

The team infused watercress and other plants with three different nanoparticles in a pressurized bath. The nanoparticles were loaded with light-emitting luciferin; luciferase, which modifies luciferin and makes it glow; and coenzyme A, which boosts luciferase activity. Using size and surface charge to control where the sets of nanoparticles could go within the plant tissues, the researchers could optimize how much light was emitted. Their watercress was half as bright as a commercial 1 microwatt LED and 100,000 times brighter than genetically engineered tobacco plants. Also, the plant could be turned off by adding a compound that blocks luciferase from activating luciferin’s glow.

Here’s a video from MIT detailing their research,

A December 13, 2017 MIT news release (also on EurekAlert) casts more light on the topic (I couldn’t resist the word play),

Imagine that instead of switching on a lamp when it gets dark, you could read by the light of a glowing plant on your desk.

MIT engineers have taken a critical first step toward making that vision a reality. By embedding specialized nanoparticles into the leaves of a watercress plant, they induced the plants to give off dim light for nearly four hours. They believe that, with further optimization, such plants will one day be bright enough to illuminate a workspace.

“The vision is to make a plant that will function as a desk lamp — a lamp that you don’t have to plug in. The light is ultimately powered by the energy metabolism of the plant itself,” says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT and the senior author of the study

This technology could also be used to provide low-intensity indoor lighting, or to transform trees into self-powered streetlights, the researchers say.

MIT postdoc Seon-Yeong Kwak is the lead author of the study, which appears in the journal Nano Letters.

Nanobionic plants

Plant nanobionics, a new research area pioneered by Strano’s lab, aims to give plants novel features by embedding them with different types of nanoparticles. The group’s goal is to engineer plants to take over many of the functions now performed by electrical devices. The researchers have previously designed plants that can detect explosives and communicate that information to a smartphone, as well as plants that can monitor drought conditions.

Lighting, which accounts for about 20 percent of worldwide energy consumption, seemed like a logical next target. “Plants can self-repair, they have their own energy, and they are already adapted to the outdoor environment,” Strano says. “We think this is an idea whose time has come. It’s a perfect problem for plant nanobionics.”

To create their glowing plants, the MIT team turned to luciferase, the enzyme that gives fireflies their glow. Luciferase acts on a molecule called luciferin, causing it to emit light. Another molecule called co-enzyme A helps the process along by removing a reaction byproduct that can inhibit luciferase activity.

The MIT team packaged each of these three components into a different type of nanoparticle carrier. The nanoparticles, which are all made of materials that the U.S. Food and Drug Administration classifies as “generally regarded as safe,” help each component get to the right part of the plant. They also prevent the components from reaching concentrations that could be toxic to the plants.

The researchers used silica nanoparticles about 10 nanometers in diameter to carry luciferase, and they used slightly larger particles of the polymers PLGA and chitosan to carry luciferin and coenzyme A, respectively. To get the particles into plant leaves, the researchers first suspended the particles in a solution. Plants were immersed in the solution and then exposed to high pressure, allowing the particles to enter the leaves through tiny pores called stomata.

Particles releasing luciferin and coenzyme A were designed to accumulate in the extracellular space of the mesophyll, an inner layer of the leaf, while the smaller particles carrying luciferase enter the cells that make up the mesophyll. The PLGA particles gradually release luciferin, which then enters the plant cells, where luciferase performs the chemical reaction that makes luciferin glow.

The researchers’ early efforts at the start of the project yielded plants that could glow for about 45 minutes, which they have since improved to 3.5 hours. The light generated by one 10-centimeter watercress seedling is currently about one-thousandth of the amount needed to read by, but the researchers believe they can boost the light emitted, as well as the duration of light, by further optimizing the concentration and release rates of the components.

Plant transformation

Previous efforts to create light-emitting plants have relied on genetically engineering plants to express the gene for luciferase, but this is a laborious process that yields extremely dim light. Those studies were performed on tobacco plants and Arabidopsis thaliana, which are commonly used for plant genetic studies. However, the method developed by Strano’s lab could be used on any type of plant. So far, they have demonstrated it with arugula, kale, and spinach, in addition to watercress.

For future versions of this technology, the researchers hope to develop a way to paint or spray the nanoparticles onto plant leaves, which could make it possible to transform trees and other large plants into light sources.

“Our target is to perform one treatment when the plant is a seedling or a mature plant, and have it last for the lifetime of the plant,” Strano says. “Our work very seriously opens up the doorway to streetlamps that are nothing but treated trees, and to indirect lighting around homes.”

The researchers have also demonstrated that they can turn the light off by adding nanoparticles carrying a luciferase inhibitor. This could enable them to eventually create plants that shut off their light emission in response to environmental conditions such as sunlight, the researchers say.

Here’s a link to and a citation for the paper,

A Nanobionic Light-Emitting Plant by Seon-Yeong Kwak, Juan Pablo Giraldo, Min Hao Wong, Volodymyr B. Koman, Tedrick Thomas Salim Lew, Jon Ell, Mark C. Weidman, Rosalie M. Sinclair, Markita P. Landry, William A. Tisdale, and Michael S. Strano. Nano Lett., 2017, 17 (12), pp 7951–7961 DOI: 10.1021/acs.nanolett.7b04369 Publication Date (Web): November 17, 2017

Copyright © 2017 American Chemical Society

This paper is behind a paywall.

Felted carbon nanotubes

Parachute (sculpted felt lantern). Artist and artisan felter: Chantal Cardinal. Studio: FELT à la main with LOVE

Scientists from Kiel University (Christian-Albrechts-Universität zu Kiel; Germany) and the University of Trento (Italy) claim to have developed a new method for integrating carbon nanotubes (CNTs) into new materials in a technique they describe as similar to felting according to a November 21, 2017 news item on Nanowerk,

Extremely lightweight, electrically highly conductive, and more stable than steel: due to their unique properties, carbon nanotubes would be ideal for numerous applications, from ultra-lightweight batteries to high-performance plastics, right through to medical implants. However, to date it has been difficult for science and industry to transfer the extraordinary characteristics at the nanoscale into a functional industrial application. The carbon nanotubes either cannot be combined adequately with other materials, or if they can be combined, they then lose their beneficial properties.

Scientists from the Functional Nanomaterials working group at Kiel University (CAU) and the University of Trento have now developed an alternative method, with which the tiny tubes can be combined with other materials, so that they retain their characteristic properties. As such, they “felt” the thread-like tubes into a stable 3D network that is able to withstand extreme forces.

In contrast to the ‘felted’ image which opened this posting, here’s an image of the ‘felted’ carbon nanotubes,

In this new process, the tiny, thread-like carbon nanotubes (CNTs) arrange themselves – almost like felting – to form a stable, tear-resistant layer. Photo/Copyright: Fabian Schütt Courtesy: Kiel University

A November 21, 2017 Kiel University press release (also on EurekAlert), which originated the news item, expands on the theme and adds another analogy,

Industry and science have been intensively researching the significantly less than one hundred nanometre wide carbon tubes (carbon nanotubes, CNTs), in order to make use of the extraordinary properties of rolled graphene. Yet much still remains just theory. “Although carbon nanotubes are flexible like fibre strands, they are also very sensitive to changes,” explained Professor Rainer Adelung, head of the Functional Nanomaterials working group at the CAU. “With previous attempts to chemically connect them with other materials, their molecular structure also changed. This, however, made their properties deteriorate – mostly drastically.”

In contrast, the approach of the research team from Kiel and Trento is based on a simple wet chemical infiltration process. The CNTs are mixed with water and dripped into an extremely porous ceramic material made of zinc oxide, which absorbs the liquid like a sponge. The dripped thread-like CNTs attach themselves to the ceramic scaffolding, and automatically form a stable layer together, similar to a felt. The ceramic scaffolding is coated with nanotubes, so to speak. This has fascinating effects, both for the scaffolding as well as for the coating of nanotubes.

On the one hand, the stability of the ceramic scaffold increases so massively that it can bear 100,000 times its own weight. “With the CNT coating, the ceramic material can hold around 7.5kg, and without it just 50g – as if we had fitted it with a close-fitting pullover made of carbon nanotubes, which provide mechanical support,” summarised first author Fabian Schütt. “The pressure on the material is absorbed by the tensile strength of the CNT felt. Compressive forces are transformed into tensile forces.”

The principle behind this is comparable with bamboo buildings [emphasis mine], such as those widespread in Asia. Here, bamboo stems are bound so tightly with a simple rope that the lightweight material can form extremely stable scaffolding, and even entire buildings. “We do the same at the nano-scale with the CNT threads, which wrap themselves around the ceramic material – only much, much smaller,” said Helge Krüger, co-author of the publication.

The materials scientists were able to demonstrate another major advantage of their process. In a second step, they dissolved the ceramic scaffolding by using a chemical etching process. All that remains is a fine 3D network of tubes, each of which consists of a layer of tiny CNT tubes. In this way, the researchers were able to greatly increase the felt surface, and thus create more opportunities for reactions. “We basically pack the surface of an entire beach volleyball field into a one centimetre cube,” explained Schütt. The huge hollow spaces inside the three-dimensional structure can then be filled with a polymer. As such, CNTs can be connected mechanically with plastics, without their molecular structure – and thus their properties – being modified. “We can specifically arrange the CNTs and manufacture an electrically conductive composite material. To do so only requires a fraction of the usual quantity of CNTs, in order to achieve the same conductivity,” said Schütt.

Applications for use range from battery and filter technology as a filling material for conductive plastics, implants for regenerative medicine, right through to sensors and electronic components at the nano-scale. The good electrical conductivity of the tear-resistant material could in future also be interesting for flexible electronics applications, in functional clothing or in the field of medical technology, for example. “Creating a plastic which, for example, stimulates bone or heart cells to grow is conceivable,” said Adelung. Due to its simplicity, the scientists agree that the process could also be transferred to network structures made of other nanomaterials – which will further expand the range of possible applications.

So, we have ‘felting’ and bamboo buildings. I can appreciate the temptation to use multiple analogies especially since I’ve given into it, on occasion.  But, it’s never considered good style, not even when I do it.

Getting back to the work at hand, here’s a link to and a citation for the paper,

Hierarchical self-entangled carbon nanotube tube networks by Fabian Schütt, Stefano Signetti, Helge Krüger, Sarah Röder, Daria Smazna, Sören Kaps, Stanislav N. Gorb, Yogendra Kumar Mishra, Nicola M. Pugno, & Rainer Adelung. Nature Communications 8, Article number: 1215 (2017) doi:10.1038/s41467-017-01324-7 Published online: 31 October 2017

This is an open access paper.

One final comment, I notice that one of the authors is Nicola Pugno who was last mentioned here in an August 30, 2017 posting titled: Making spider silk stronger by feeding graphene and carbon nanotubes to spiders.

Limitless energy and the International Thermonuclear Experimental Reactor (ITER)

Over 30 years in the dreaming, the International Thermonuclear Experimental Reactor (ITER) is now said to be 1/2 way to completing construction. A December 6, 2017 ITER press release (received via email) makes the joyful announcement,

WORLD’S MOST COMPLEX MACHINE IS 50 PERCENT COMPLETED
ITER is proving that fusion is the future source of clean, abundant, safe and economic energy_

The International Thermonuclear Experimental Reactor (ITER), a project to prove that fusion power can be produced on a commercial scale and is sustainable, is now 50 percent built to initial operation. Fusion is the same energy source from the Sun that gives the Earth its light and warmth.

ITER will use hydrogen fusion, controlled by superconducting magnets, to produce massive heat energy. In the commercial machines that will follow, this heat will drive turbines to produce electricity with these positive benefits:

* Fusion energy is carbon-free and environmentally sustainable, yet much more powerful than fossil fuels. A pineapple-sized amount of hydrogen offers as much fusion energy as 10,000 tons of coal.

* ITER uses two forms of hydrogen fuel: deuterium, which is easily extracted from seawater; and tritium, which is bred from lithium inside the fusion reactor. The supply of fusion fuel for industry and megacities is abundant, enough for millions of years.

* When the fusion reaction is disrupted, the reactor simply shuts down-safely and without external assistance. Tiny amounts of fuel are used, about 2-3 grams at a time; so there is no physical possibility of a meltdown accident.

* Building and operating a fusion power plant is targeted to be comparable to the cost of a fossil fuel or nuclear fission plant. But unlike today’s nuclear plants, a fusion plant will not have the costs of high-level radioactive waste disposal. And unlike fossil fuel plants,
fusion will not have the environmental cost of releasing CO2 and other pollutants.

ITER is the most complex science project in human history. The hydrogen plasma will be heated to 150 million degrees Celsius, ten times hotter than the core of the Sun, to enable the fusion reaction. The process happens in a donut-shaped reactor, called a tokamak(*), which is surrounded by giant magnets that confine and circulate the superheated, ionized plasma, away from the metal walls. The superconducting magnets must be cooled to minus 269°C, as cold as interstellar space.

The ITER facility is being built in Southern France by a scientific partnership of 35 countries. ITER’s specialized components, roughly 10 million parts in total, are being manufactured in industrial facilities all over the world. They are subsequently shipped to the ITER worksite, where they must be assembled, piece-by-piece, into the final machine.

Each of the seven ITER members-the European Union, China, India, Japan, Korea, Russia, and the United States-is fabricating a significant portion of the machine. This adds to ITER’s complexity.

In a message dispatched on December 1 [2017] to top-level officials in ITER member governments, the ITER project reported that it had completed 50 percent of the “total construction work scope through First Plasma” (**). First Plasma, scheduled for December 2025, will be the first stage of operation for ITER as a functional machine.

“The stakes are very high for ITER,” writes Bernard Bigot, Ph.D., Director-General of ITER. “When we prove that fusion is a viable energy source, it will eventually replace burning fossil fuels, which are non-renewable and non-sustainable. Fusion will be complementary with wind, solar, and other renewable energies.

“ITER’s success has demanded extraordinary project management, systems engineering, and almost perfect integration of our work.

“Our design has taken advantage of the best expertise of every member’s scientific and industrial base. No country could do this alone. We are all learning from each other, for the world’s mutual benefit.”

The ITER 50 percent milestone is getting significant attention.

“We are fortunate that ITER and fusion has had the support of world leaders, historically and currently,” says Director-General Bigot. “The concept of the ITER project was conceived at the 1985 Geneva Summit between Ronald Reagan and Mikhail Gorbachev. When the ITER Agreement was signed in 2006, it was strongly supported by leaders such as French President Jacques Chirac, U.S. President George W. Bush, and Indian Prime Minister Manmohan Singh.

“More recently, President Macron and U.S. President Donald Trump exchanged letters about ITER after their meeting this past July. One month earlier, President Xi Jinping of China hosted Russian President Vladimir Putin and other world leaders in a showcase featuring ITER and fusion power at the World EXPO in Astana, Kazakhstan.

“We know that other leaders have been similarly involved behind the scenes. It is clear that each ITER member understands the value and importance of this project.”

Why use this complex manufacturing arrangement?

More than 80 percent of the cost of ITER, about $22 billion or EUR18 billion, is contributed in the form of components manufactured by the partners. Many of these massive components of the ITER machine must be precisely fitted-for example, 17-meter-high magnets with less than a millimeter of tolerance. Each component must be ready on time to fit into the Master Schedule for machine assembly.

Members asked for this deal for three reasons. First, it means that most of the ITER costs paid by any member are actually paid to that member’s companies; the funding stays in-country. Second, the companies working on ITER build new industrial expertise in major fields-such as electromagnetics, cryogenics, robotics, and materials science. Third, this new expertise leads to innovation and spin-offs in other fields.

For example, expertise gained working on ITER’s superconducting magnets is now being used to map the human brain more precisely than ever before.

The European Union is paying 45 percent of the cost; China, India, Japan, Korea, Russia, and the United States each contribute 9 percent equally. All members share in ITER’s technology; they receive equal access to the intellectual property and innovation that comes from building ITER.

When will commercial fusion plants be ready?

ITER scientists predict that fusion plants will start to come on line as soon as 2040. The exact timing, according to fusion experts, will depend on the level of public urgency and political will that translates to financial investment.

How much power will they provide?

The ITER tokamak will produce 500 megawatts of thermal power. This size is suitable for studying a “burning” or largely self-heating plasma, a state of matter that has never been produced in a controlled environment on Earth. In a burning plasma, most of the plasma heating comes from the fusion reaction itself. Studying the fusion science and technology at ITER’s scale will enable optimization of the plants that follow.

A commercial fusion plant will be designed with a slightly larger plasma chamber, for 10-15 times more electrical power. A 2,000-megawatt fusion electricity plant, for example, would supply 2 million homes.

How much would a fusion plant cost and how many will be needed?

The initial capital cost of a 2,000-megawatt fusion plant will be in the range of $10 billion. These capital costs will be offset by extremely low operating costs, negligible fuel costs, and infrequent component replacement costs over the 60-year-plus life of the plant. Capital costs will decrease with large-scale deployment of fusion plants.

At current electricity usage rates, one fusion plant would be more than enough to power a city the size of Washington, D.C. The entire D.C. metropolitan area could be powered with four fusion plants, with zero carbon emissions.

“If fusion power becomes universal, the use of electricity could be expanded greatly, to reduce the greenhouse gas emissions from transportation, buildings and industry,” predicts Dr. Bigot. “Providing clean, abundant, safe, economic energy will be a miracle for our planet.”

*     *     *

FOOTNOTES:

* “Tokamak” is a word of Russian origin meaning a toroidal or donut-shaped magnetic chamber. Tokamaks have been built and operated for the past six decades. They are today’s most advanced fusion device design.

** “Total construction work scope,” as used in ITER’s project performance metrics, includes design, component manufacturing, building construction, shipping and delivery, assembly, and installation.

It is an extraordinary project on many levels as Henry Fountain notes in a March 27, 2017 article for the New York Times (Note: Links have been removed),

At a dusty construction site here amid the limestone ridges of Provence, workers scurry around immense slabs of concrete arranged in a ring like a modern-day Stonehenge.

It looks like the beginnings of a large commercial power plant, but it is not. The project, called ITER, is an enormous, and enormously complex and costly, physics experiment. But if it succeeds, it could determine the power plants of the future and make an invaluable contribution to reducing planet-warming emissions.

ITER, short for International Thermonuclear Experimental Reactor (and pronounced EAT-er), is being built to test a long-held dream: that nuclear fusion, the atomic reaction that takes place in the sun and in hydrogen bombs, can be controlled to generate power.

ITER will produce heat, not electricity. But if it works — if it produces more energy than it consumes, which smaller fusion experiments so far have not been able to do — it could lead to plants that generate electricity without the climate-affecting carbon emissions of fossil-fuel plants or most of the hazards of existing nuclear reactors that split atoms rather than join them.

Success, however, has always seemed just a few decades away for ITER. The project has progressed in fits and starts for years, plagued by design and management problems that have led to long delays and ballooning costs.

ITER is moving ahead now, with a director-general, Bernard Bigot, who took over two years ago after an independent analysis that was highly critical of the project. Dr. Bigot, who previously ran France’s atomic energy agency, has earned high marks for resolving management problems and developing a realistic schedule based more on physics and engineering and less on politics.

The site here is now studded with tower cranes as crews work on the concrete structures that will support and surround the heart of the experiment, a doughnut-shaped chamber called a tokamak. This is where the fusion reactions will take place, within a plasma, a roiling cloud of ionized atoms so hot that it can be contained only by extremely strong magnetic fields.

Here’s a rendering of the proposed reactor,

Source: ITER Organization

It seems the folks at the New York Times decided to remove the notes which help make sense of this image. However, it does get the idea across.

If I read the article rightly, the official cost in March 2017 was around 22 B Euros and more will likely be needed. You can read Fountain’s article for more information about fusion and ITER or go to the ITER website.

I could have sworn a local (Vancouver area) company called General Fusion was involved in the ITER project but I can’t track down any sources for confirmation. The sole connection I could find is in a documentary about fusion technology,

Here’s a little context for the film from a July 4, 2017 General Fusion news release (Note: A link has been removed),

A new documentary featuring General Fusion has captured the exciting progress in fusion across the public and private sectors.

Let There Be Light made its international premiere at the South By Southwest (SXSW) music and film festival in March [2017] to critical acclaim. The film was quickly purchased by Amazon Video, where it will be available for more than 70 million users to stream.

Let There Be Light follows scientists at General Fusion, ITER and Lawrenceville Plasma Physics in their pursuit of a clean, safe and abundant source of energy to power the world.

The feature length documentary has screened internationally across Europe and North America. Most recently it was shown at the Hot Docs film festival in Toronto, where General Fusion founder and Chief Scientist Dr. Michel Laberge joined fellow fusion physicist Dr. Mark Henderson from ITER at a series of Q&A panels with the filmmakers.

Laberge and Henderson were also interviewed by the popular CBC radio science show Quirks and Quarks, discussing different approaches to fusion, its potential benefits, and the challenges it faces.

It is yet to be confirmed when the film will be release for streaming, check Amazon Video for details.

You can find out more about General Fusion here.

Brief final comment

ITER is a breathtaking effort but if you’ve read about other large scale projects such as building a railway across the Canadian Rocky Mountains, establishing telecommunications in an  astonishing number of countries around the world, getting someone to the moon, eliminating small pox, building the pyramids, etc., it seems standard operating procedure both for the successes I’ve described and for the failures we’ve forgotten. Where ITER will finally rest on the continuum between success and failure is yet to be determined but the problems experienced so far are not necessarily a predictor.

I wish the engineers, scientists, visionaries, and others great success with finding better ways to produce energy.

Vampire nanogenerators: 2017

Researchers have been working on ways to harvest energy from bloodstreams. I last wrote about this type of research in an April 3, 2009 posting about ‘vampire batteries ‘(for use in pacemakers). The latest work according to a Sept. 8, 2017 news item on Nanowerk comes from China,

Men build dams and huge turbines to turn the energy of waterfalls and tides into electricity. To produce hydropower on a much smaller scale, Chinese scientists have now developed a lightweight power generator based on carbon nanotube fibers suitable to convert even the energy of flowing blood in blood vessels into electricity. They describe their innovation in the journal Angewandte Chemie (“A One-Dimensional Fluidic Nanogenerator with a High Power Conversion Efficiency”)

A Sept. 8, 2017 Wiley Publishing news release (also on EurekAlert), which originated the news item, expands on the theme,

For thousands of years, people have used the energy of flowing or falling water for their purposes, first to power mechanical engines such as watermills, then to generate electricity by exploiting height differences in the landscape or sea tides. Using naturally flowing water as a sustainable power source has the advantage that there are (almost) no dependencies on weather or daylight. Even flexible, minute power generators that make use of the flow of biological fluids are conceivable. How such a system could work is explained by a research team from Fudan University in Shanghai, China. Huisheng Peng and his co-workers have developed a fiber with a thickness of less than a millimeter that generates electrical power when surrounded by flowing saline solution—in a thin tube or even in a blood vessel.

The construction principle of the fiber is quite simple. An ordered array of carbon nanotubes was continuously wrapped around a polymeric core. Carbon nanotubes are well known to be electroactive and mechanically stable; they can be spun and aligned in sheets. In the as-prepared electroactive threads, the carbon nanotube sheets coated the fiber core with a thickness of less than half a micron. For power generation, the thread or “fiber-shaped fluidic nanogenerator” (FFNG), as the authors call it, was connected to electrodes and immersed into flowing water or simply repeatedly dipped into a saline solution. “The electricity was derived from the relative movement between the FFNG and the solution,” the scientists explained. According to the theory, an electrical double layer is created around the fiber, and then the flowing solution distorts the symmetrical charge distribution, generating an electricity gradient along the long axis.

The power output efficiency of this system was high. Compared with other types of miniature energy-harvesting devices, the FFNG was reported to show a superior power conversion efficiency of more than 20%. Other advantages are elasticity, tunability, lightweight, and one-dimensionality, thus offering prospects of exciting technological applications. The FFNG can be made stretchable just by spinning the sheets around an elastic fiber substrate. If woven into fabrics, wearable electronics become thus a very interesting option for FFNG application. Another exciting application is the harvesting of electrical energy from the bloodstream for medical applications. First tests with frog nerves proved to be successful.

Here’s a link to and a citation for the paper,

A One-Dimensional Fluidic Nanogenerator with a High Power Conversion Efficiency by Yifan Xu, Dr. Peining Chen, Jing Zhang, Songlin Xie, Dr. Fang Wan, Jue Deng, Dr. Xunliang Cheng, Yajie Hu, Meng Liao, Dr. Bingjie Wang, Dr. Xuemei Sun, and Prof. Dr. Huisheng Peng. Angewandte Chemie International Edition DOI: 10.1002/anie.201706620 Version of Record online: 7 SEP 2017

© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Beautiful solar cells based on insect eyes

What a gorgeous image!

The compound eye of a fly inspired Stanford researchers to create a compound solar cell consisting of perovskite microcells encapsulated in a hexagon-shaped scaffold. (Image credit: Thomas Shahan/Creative Commons)

An August 31, 2017 news item on Nanowerk describes research into solar cells being performed at Stanford University (Note: A link has been removed),

Packing tiny solar cells together, like micro-lenses in the compound eye of an insect, could pave the way to a new generation of advanced photovoltaics, say Stanford University scientists.

In a new study, the Stanford team used the insect-inspired design to protect a fragile photovoltaic material called perovskite from deteriorating when exposed to heat, moisture or mechanical stress. The results are published in the journal Energy & Environmental Science (“Scaffold-reinforced perovskite compound solar cells”).

An August 31, 2017 Stanford University news release (also on EurekAlert) by Mark Schwartz, which originated the news item,

“Perovskites are promising, low-cost materials that convert sunlight to electricity as efficiently as conventional solar cells made of silicon,” said Reinhold Dauskardt, a professor of materials science and engineering and senior author of the study. “The problem is that perovskites are extremely unstable and mechanically fragile. They would barely survive the manufacturing process, let alone be durable long term in the environment.”

Most solar devices, like rooftop panels, use a flat, or planar, design. But that approach doesn’t work well with perovskite solar cells.

“Perovskites are the most fragile materials ever tested in the history of our lab,” said graduate student Nicholas Rolston, a co-lead author of the E&ES study. “This fragility is related to the brittle, salt-like crystal structure of perovskite, which has mechanical properties similar to table salt.”

Eye of the fly

To address the durability challenge, the Stanford team turned to nature.

“We were inspired by the compound eye of the fly, which consists of hundreds of tiny segmented eyes,” Dauskardt explained. “It has a beautiful honeycomb shape with built-in redundancy: If you lose one segment, hundreds of others will operate. Each segment is very fragile, but it’s shielded by a scaffold wall around it.”

Scaffolds in a compound solar cell filled with perovskite after fracture testing.

Scaffolds in a compound solar cell filled with perovskite after fracture testing. (Image credit: Dauskardt Lab/Stanford University)

Using the compound eye as a model, the researchers created a compound solar cell consisting of a vast honeycomb of perovskite microcells, each encapsulated in a hexagon-shaped scaffold just 0.02 inches (500 microns) wide.

“The scaffold is made of an inexpensive epoxy resin widely used in the microelectronics industry,” Rolston said. “It’s resilient to mechanical stresses and thus far more resistant to fracture.”

Tests conducted during the study revealed that the scaffolding had little effect on how efficiently perovskite converted light into electricity.

“We got nearly the same power-conversion efficiencies out of each little perovskite cell that we would get from a planar solar cell,” Dauskardt said. “So we achieved a huge increase in fracture resistance with no penalty for efficiency.”

Durability

But could the new device withstand the kind of heat and humidity that conventional rooftop solar panels endure?

To find out, the researchers exposed encapsulated perovskite cells to temperatures of 185 F (85 C) and 85 percent relative humidity for six weeks. Despite these extreme conditions, the cells continued to generate electricity at relatively high rates of efficiency.

Dauskardt and his colleagues have filed a provisional patent for the new technology. To improve efficiency, they are studying new ways to scatter light from the scaffold into the perovskite core of each cell.

“We are very excited about these results,” he said. “It’s a new way of thinking about designing solar cells. These scaffold cells also look really cool, so there are some interesting aesthetic possibilities for real-world applications.”

Researchers have also made this image available,

Caption: A compound solar cell illuminated from a light source below. Hexagonal scaffolds are visible in the regions coated by a silver electrode. The new solar cell design could help scientists overcome a major roadblock to the development of perovskite photovoltaics. Credit: Dauskardt Lab/Stanford University

Not quite as weirdly beautiful as the insect eyes.

Here’s a link to and a citation for the paper,

Scaffold-reinforced perovskite compound solar cells by Brian L. Watson, Nicholas Rolston, Adam D. Printz, and Reinhold H. Dauskardt. Energy & Environmental Science 2017 DOI: 10.1039/C7EE02185B first published on 23 Aug 2017

This paper is behind a paywall.

Cyborg bacteria to reduce carbon dioxide

This video is a bit technical but then it is about work being presented to chemists at the American Chemical Society’s (ACS) at the 254th National Meeting & Exposition Aug. 20 -24, 2017,

For a more plain language explanation, there’s an August 22, 2017 ACS news release (also on EurekAlert),

Photosynthesis provides energy for the vast majority of life on Earth. But chlorophyll, the green pigment that plants use to harvest sunlight, is relatively inefficient. To enable humans to capture more of the sun’s energy than natural photosynthesis can, scientists have taught bacteria to cover themselves in tiny, highly efficient solar panels to produce useful compounds.

“Rather than rely on inefficient chlorophyll to harvest sunlight, I’ve taught bacteria how to grow and cover their bodies with tiny semiconductor nanocrystals,” says Kelsey K. Sakimoto, Ph.D., who carried out the research in the lab of Peidong Yang, Ph.D. “These nanocrystals are much more efficient than chlorophyll and can be grown at a fraction of the cost of manufactured solar panels.”

Humans increasingly are looking to find alternatives to fossil fuels as sources of energy and feedstocks for chemical production. Many scientists have worked to create artificial photosynthetic systems to generate renewable energy and simple organic chemicals using sunlight. Progress has been made, but the systems are not efficient enough for commercial production of fuels and feedstocks.

Research in Yang’s lab at the University of California, Berkeley, where Sakimoto earned his Ph.D., focuses on harnessing inorganic semiconductors that can capture sunlight to organisms such as bacteria that can then use the energy to produce useful chemicals from carbon dioxide and water. “The thrust of research in my lab is to essentially ‘supercharge’ nonphotosynthetic bacteria by providing them energy in the form of electrons from inorganic semiconductors, like cadmium sulfide, that are efficient light absorbers,” Yang says. “We are now looking for more benign light absorbers than cadmium sulfide to provide bacteria with energy from light.”

Sakimoto worked with a naturally occurring, nonphotosynthetic bacterium, Moorella thermoacetica, which, as part of its normal respiration, produces acetic acid from carbon dioxide (CO2). Acetic acid is a versatile chemical that can be readily upgraded to a number of fuels, polymers, pharmaceuticals and commodity chemicals through complementary, genetically engineered bacteria.

When Sakimoto fed cadmium and the amino acid cysteine, which contains a sulfur atom, to the bacteria, they synthesized cadmium sulfide (CdS) nanoparticles, which function as solar panels on their surfaces. The hybrid organism, M. thermoacetica-CdS, produces acetic acid from CO2, water and light. “Once covered with these tiny solar panels, the bacteria can synthesize food, fuels and plastics, all using solar energy,” Sakimoto says. “These bacteria outperform natural photosynthesis.”

The bacteria operate at an efficiency of more than 80 percent, and the process is self-replicating and self-regenerating, making this a zero-waste technology. “Synthetic biology and the ability to expand the product scope of CO2 reduction will be crucial to poising this technology as a replacement, or one of many replacements, for the petrochemical industry,” Sakimoto says.

So, do the inorganic-biological hybrids have commercial potential? “I sure hope so!” he says. “Many current systems in artificial photosynthesis require solid electrodes, which is a huge cost. Our algal biofuels are much more attractive, as the whole CO2-to-chemical apparatus is self-contained and only requires a big vat out in the sun.” But he points out that the system still requires some tweaking to tune both the semiconductor and the bacteria. He also suggests that it is possible that the hybrid bacteria he created may have some naturally occurring analog. “A future direction, if this phenomenon exists in nature, would be to bioprospect for these organisms and put them to use,” he says.

For more insight into the work, check out Dexter Johnson’s Aug. 22, 2017 posting on his Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website),

“It’s actually a natural, overlooked feature of their biology,” explains Sakimoto in an e-mail interview with IEEE Spectrum. “This bacterium has a detoxification pathway, meaning if it encounters a toxic metal, like cadmium, it will try to precipitate it out, thereby detoxifying it. So when we introduce cadmium ions into the growth medium in which M. thermoacetica is hanging out, it will convert the amino acid cysteine into sulfide, which precipitates out cadmium as cadmium sulfide. The crystals then assemble and stick onto the bacterium through normal electrostatic interactions.”

I’ve just excerpted one bit, there’s more in Dexter’s posting.

Burning coal produces harmful titanium dioxide nanoparticles

It turns out that Canada has the fifth largest reserve of coal in the world, according to the Coal in Canada Wikipedia entry (Note: Links have been removed),

Coal reserves in Canada rank fifth largest in the world (following the former Soviet Union, the United States, the People’s Republic of China and Australia) at approximately 10 billion tons, 10% of the world total.[1] This represents more energy than all of the oil and gas in the country combined. The coal industry generates CDN$5 billion annually.[2] Most of Canada’s coal mining occurs in the West of the country.[3] British Columbia operates 10 coal mines, Alberta 9, Saskatchewan 3 and New Brunswick one. Nova Scotia operates several small-scale mines, Westray having closed following the 1992 disaster there.[4]

So, this news from Virginia holds more than the usual interest for me (I’m in British Columbia). From an Aug. 8, 2017 Virginia Tech news release (also on EurekAlert),

Environmental scientists led by the Virginia Tech College of Science have discovered that the burning of coal produces incredibly small particles of a highly unusual form of titanium oxide.

When inhaled, these nanoparticles can enter the lungs and potentially the bloodstream.

The particulates — known as titanium suboxide nanoparticles — are unintentionally produced as coal is burned, creating these tiniest of particles, as small as 100 millionths of a meter [emphasis mine], said the Virginia Tech-led team. When the particles are introduced into the air — unless captured by high-tech particle traps — they can float away from power plant stacks and travel on air currents locally, regionally, and even globally.

As an example of this, these nanoparticles were found on city streets, sidewalks, and in standing water in Shanghai, China.

The findings are published in the latest issue of Nature Communications under team leader Michael F. Hochella Jr., University Distinguished Professor of Geosciences with the College of Science, and Yi Yang, a professor at East China Normal University in Shanghai. Other study participants include Duke University, the University of Kentucky, and Laurentian University in Canada.

“The problem with these nanoparticles is that there is no easy or practical way to prevent their formation during coal burning,” Hochella said, adding that in nations with strong environmental regulations, such as the United States, most of the nanoparticles would be caught by particle traps. Not so in Africa [a continent not a nation], China, or India, where regulations are lax or nonexistent, with coal ash and smoke entering the open air.

“Due to advanced technology used at U.S.-based coal burning power plants, mandated by the Clean Air Act and the Environmental Protection Agency, most of these nanoparticles and other tiny particles are removed before the final emission of the plant’s exhaust gases,” Hochella said. “But in countries where the particles from the coal burning are not nearly so efficiently removed, or removed at all, these titanium suboxide nanoparticles and many other particle types are emitted into the atmosphere, in part resulting in hazy skies that plague many countries, especially in China and India.”

Hochella and his team found these previously unknown nanoparticles not only in coal ash from around the world and in the gaseous waste emissions of coal plants, but on city streets, in soils and storm water ponds, and at wastewater treatment plants.

“I could not believe what I have found at the beginning, because they had been reported so extremely rarely in the natural environment,” said Yang, who once worked as a visiting professor in Virginia Tech’s Department of Geosciences with Hochella. “It took me several months to confirm their occurrence in coal ash samples.”

The newly found titanium suboxide — called Magnéli phases — was once thought rare, found only sparingly on Earth in some meteorites, from a small area of rock formations in western Greenland, and occasionally in moon rocks. The findings by Hochella and his team indicate that these nanoparticles are in fact widespread globally. They are only now being studied for the first time in natural environments using powerful electron microscopes.

Why did the discovery occur now? According to the report, nearly all coal contains traces of the minerals rutile and/or anatase, both “normal,” naturally occurring, and relatively inert titanium oxides, especially in the absence of light. When those minerals are burned in the presence of coal, research found they easily and quickly converted to these unusual titanium suboxide nanoparticles. The nanoparticles then become entrained in the gases that leave the power plant.

When inhaled, the nanoparticles enter deep into the lungs, potentially all the way into the air sacs that move oxygen into our bloodstream during the normal breathing process. While human lung toxicity of these particles is not yet known, a preliminary biotoxicity test by Hochella and Richard Di Giulio, professor of environmental toxicology, and Jessica Brandt, a doctoral candidate, both at Duke University, indicates that the particles do indeed have toxicity potential.

According to the team, further study is clearly needed, especially biotoxicity testing directly relevant to the human lung. Partnering with coal-power plants either in the United States or China would be ideal, said Yang.

More troubling, the study shows that titanium suboxide nanoparticles are biologically active in the dark, making the particles highly suspect. Exact human health effects are yet unknown.

“Future studies will need to very carefully investigate and access the toxicity of titanium suboxide nanoparticles in the human lung, and this could take years, a sobering thought considering its potential danger,” Hochella said.

As the titanium suboxide nanoparticle itself is produced incidentally, Hochella and his team came across the nanoparticle by accident while studying a 2014 coal ash spill in the Dan River, North Carolina. During the study of the downstream movement of toxic metals in the ash in the Dan River, the team discovered and recognized the presence of small amounts of the highly unusual titanium suboxide.

The group later produced the titanium suboxide nanoparticles when burning coal in a lab simulation.

This new potential air pollution health hazard builds on already established findings from the World Health Organization. It estimates that 3.3 million premature deaths occur worldwide per year due to polluted air, Hochella said. In China, 1.6 million premature deaths are estimated annually due to cardiovascular and respiratory injury from air pollution. Most Chinese megacities top 100 severely hazy days each year with particle concentrations two to four times higher than WHO guidelines, Yang said.

Direct health effects on humans is only one factor. Findings of thousands of scientists have determined that the biggest driver of warming of the planet and the resulting climate change is industrial-scale coal burning. The impact of titanium suboxide nanoparticles found in the atmosphere, in addition to greenhouse gases, on animals, water, and plants is not yet known.

They’ve used an unusual unit of measurement, “100 millionths of a meter,” nanoparticles are usually described in nanometers.

Here’s a link to and a citation for the paper,

Discovery and ramifications of incidental Magnéli phase generation and release from industrial coal-burning by Yi Yang, Bo Chen, James Hower, Michael Schindler, Christopher Winkler, Jessica Brandt, Richard Di Giulio, Jianping Ge, Min Liu, Yuhao Fu, Lijun Zhang, Yuru Chen, Shashank Priya, & Michael F. Hochella Jr. Nature Communications 8, Article number: 194 (2017) doi:10.1038/s41467-017-00276-2 Published online: 08 August 2017

This paper is behind a paywall.

This put me in mind of the famous London smog, which one doesn’t hear about much anymore. For anyone not familiar with that phenomenon, here’s more from the Great Smog of London Wikipedia entry (Note: Links have been removed),

The Great Smog of London, or Great Smog of 1952 sometimes called the Big Smoke,[1] was a severe air-pollution event [emphasis mine] that affected the British capital of London in December 1952. A period of cold weather, combined with an anticyclone and windless conditions, collected airborne pollutants – mostly arising from the use of coal [emphasis mine]– to form a thick layer of smog over the city. It lasted from Friday, 5 December to Tuesday, 9 December 1952 and then dispersed quickly when the weather changed.

It caused major disruption by reducing visibility and even penetrating indoor areas, far more severe than previous smog events experienced in the past, called “pea-soupers”. Government medical reports in the following weeks, however, estimated that up until 8 December, 4,000 people had died as a direct result of the smog and 100,000 more were made ill by the smog’s effects on the human respiratory tract. More recent research suggests that the total number of fatalities was considerably greater, about 12,000.[2]

London had suffered since the 1200s from poor air quality,[3] which worsened in the 1600s,[4][5] but the Great Smog is known to be the worst air-pollution event in the history of the United Kingdom,[6] and the most significant in terms of its effect on environmental research, government regulation, and public awareness of the relationship between air quality and health.[2][4] It led to several changes in practices and regulations, including the Clean Air Act 1956. …

A candy cane supercapacitor?

Courtesy: Queen Mary University of London

It takes a lot more imagination than I have to describe the object on the right as resembling the  candy cane on the left, assuming that’s what was intended when it was used to illustrate the university’s press release. I like being pushed to see resemblances to things that are not immediately apparent to me. This may never look like a candy cane to me but I appreciate that someone finds it to be so. An August 16, 2017 news item on ScienceDaily announces the ‘candy cane’ supercapacitor,

Supercapacitors promise recharging of phones and other devices in seconds and minutes as opposed to hours for batteries. But current technologies are not usually flexible, have insufficient capacities, and for many their performance quickly degrades with charging cycles.

Researchers at Queen Mary University of London (QMUL) and the University of Cambridge have found a way to improve all three problems in one stroke.

Their prototyped polymer electrode, which resembles a candy cane usually hung on a Christmas tree, achieves energy storage close to the theoretical limit, but also demonstrates flexibility and resilience to charge/discharge cycling.

The technique could be applied to many types of materials for supercapacitors and enable fast charging of mobile phones, smart clothes and implantable devices.

The Aug. 16, 2017 Queen Mary University of London (QMUL) press release (also on EurekAlert), which originated the news item, provides more detail about the technology,

Pseudocapacitance is a property of polymer and composite supercapacitors that allows ions to enter inside the material and thus pack much more charge than carbon ones that mostly store the charge as concentrated ions (in the so-called double layer) near the surface.

The problem with polymer supercapacitors, however, is that the ions necessary for these chemical reactions can only access the top few nanometers below the material surface, leaving the rest of the electrode as dead weight. Growing polymers as nano-structures is one way to increase the amount of accessible material near the surface, but this can be expensive, hard to scale up, and often results in poor mechanical stability.

The researchers, however, have developed a way to interweave nanostructures within a bulk material, thereby achieving the benefits of conventional nanostructuring without using complex synthesis methods or sacrificing material toughness.

Project leader, Stoyan Smoukov, explained: “Our supercapacitors can store a lot of charge very quickly, because the thin active material (the conductive polymer) is always in contact with a second polymer which contains ions, just like the red thin regions of a candy cane are always in close proximity to the white parts. But this is on a much smaller scale.

“This interpenetrating structure enables the material to bend more easily, as well as swell and shrink without cracking, leading to greater longevity. This one method is like killing not just two, but three birds with one stone.”

The outcomes

The Smoukov group had previously pioneered a combinatorial route to multifunctionality using interpenetrating polymer networks (IPN) in which each component would have its own function, rather than using trial-and-error chemistry to fit all functions in one molecule.

This time they applied the method to energy storage, specifically supercapacitors, because of the known problem of poor material utilization deep beneath the electrode surface.

This interpenetration technique drastically increases the material’s surface area, or more accurately the interfacial area between the different polymer components.

Interpenetration also happens to solve two other major problems in supercapacitors. It brings flexibility and toughness because the interfaces stop growth of any cracks that may form in the material. It also allows the thin regions to swell and shrink repeatedly without developing large stresses, so they are electrochemically resistant and maintain their performance over many charging cycles.

The researchers are currently rationally designing and evaluating a range of materials that can be adapted into the interpenetrating polymer system for even better supercapacitors.

In an upcoming review, accepted for publication in the journal Sustainable Energy and Fuels, they overview the different techniques people have used to improve the multiple parameters required for novel supercapacitors.

Such devices could be made in soft and flexible freestanding films, which could power electronics embedded in smart clothing, wearable and implantable devices, and soft robotics. The developers hope to make their contribution to provide ubiquitous power for the emerging Internet of Things (IoT) devices, which is still a significant challenge ahead.

Here’s a link to and a citation for the paper,

Semi-Interpenetrating Polymer Networks for Enhanced Supercapacitor Electrodes by Kara D. Fong, Tiesheng Wang, Hyun-Kyung Kim, R. Vasant Kumar, and Stoyan K. Smoukov. ACS Energy Lett., 2017, 2, pp 2014–2020 DOI: 10.1021/acsenergylett.7b00466 Publication Date (Web): August 14, 2017

Copyright © 2017 American Chemical Society

This paper is behind a paywall.

A different type of ‘smart’ window with a new solar cell technology

I always like a ‘smart’ window story. Given my issues with summer (I don’t like the heat), anything which promises to help reduce the heat in my home at that time of year, has my vote. Unfortunately, solutions don’t seem to have made a serious impact on the marketplace. Nonetheless, there’s always hope and perhaps this development at Princeton University will be the one to break through the impasse. From a June 30, 2017 news item on ScienceDaily,

Smart windows equipped with controllable glazing can augment lighting, cooling and heating systems by varying their tint, saving up to 40 percent in an average building’s energy costs.

These smart windows require power for operation, so they are relatively complicated to install in existing buildings. But by applying a new solar cell technology, researchers at Princeton University have developed a different type of smart window: a self-powered version that promises to be inexpensive and easy to apply to existing windows. This system features solar cells that selectively absorb near-ultraviolet (near-UV) light, so the new windows are completely self-powered.

A June 30, 2017 Princeton University news release, which originated the news item, expands on the theme,

“Sunlight is a mixture of electromagnetic radiation made up of near-UV rays, visible light, and infrared energy, or heat,” said Yueh-Lin (Lynn) Loo, director of the Andlinger Center for Energy and the Environment, and the Theodora D. ’78 and William H. Walton III ’74 Professor in Engineering. “We wanted the smart window to dynamically control the amount of natural light and heat that can come inside, saving on energy cost and making the space more comfortable.”

The smart window controls the transmission of visible light and infrared heat into the building, while the new type of solar cell uses near-UV light to power the system.

“This new technology is actually smart management of the entire spectrum of sunlight,” said Loo, who is a professor of chemical and biological engineering. Loo is one of the authors of a paper, published June 30, that describes this technology, which was developed in her lab.

Because near-UV light is invisible to the human eye, the researchers set out to harness it for the electrical energy needed to activate the tinting technology.

“Using near-UV light to power these windows means that the solar cells can be transparent and occupy the same footprint of the window without competing for the same spectral range or imposing aesthetic and design constraints,” Loo added. “Typical solar cells made of silicon are black because they absorb all visible light and some infrared heat – so those would be unsuitable for this application.”

In the paper published in Nature Energy, the researchers described how they used organic semiconductors – contorted hexabenzocoronene (cHBC) derivatives – for constructing the solar cells. The researchers chose the material because its chemical structure could be modified to absorb a narrow range of wavelengths – in this case, near-UV light. To construct the solar cell, the semiconductor molecules are deposited as thin films on glass with the same production methods used by organic light-emitting diode manufacturers. When the solar cell is operational, sunlight excites the cHBC semiconductors to produce electricity.

At the same time, the researchers constructed a smart window consisting of electrochromic polymers, which control the tint, and can be operated solely using power produced by the solar cell. When near-UV light from the sun generates an electrical charge in the solar cell, the charge triggers a reaction in the electrochromic window, causing it to change from clear to dark blue. When darkened, the window can block more than 80 percent of light.

Nicholas Davy, a doctoral student in the chemical and biological engineering department and the paper’s lead author, said other researchers have already developed transparent solar cells, but those target infrared energy. However, infrared energy carries heat, so using it to generate electricity can conflict with a smart window’s function of controlling the flow of heat in or out of a building. Transparent near-UV solar cells, on the other hand, don’t generate as much power as the infrared version, but don’t impede the transmission of infrared radiation, so they complement the smart window’s task.

Davy said that the Princeton team’s aim is to create a flexible version of the solar-powered smart window system that can be applied to existing windows via lamination.

“Someone in their house or apartment could take these wireless smart window laminates – which could have a sticky backing that is peeled off – and install them on the interior of their windows,” said Davy. “Then you could control the sunlight passing into your home using an app on your phone, thereby instantly improving energy efficiency, comfort, and privacy.”

Joseph Berry, senior research scientist at the National Renewable Energy Laboratory, who studies solar cells but was not involved in the research, said the research project is interesting because the device scales well and targets a specific part of the solar spectrum.

“Integrating the solar cells into the smart windows makes them more attractive for retrofits and you don’t have to deal with wiring power,” said Berry. “And the voltage performance is quite good. The voltage they have been able to produce can drive electronic devices directly, which is technologically quite interesting.”

Davy and Loo have started a new company, called Andluca Technologies, based on the technology described in the paper, and are already exploring other applications for the transparent solar cells. They explained that the near-UV solar cell technology can also power internet-of-things sensors and other low-power consumer products.

“It does not generate enough power for a car, but it can provide auxiliary power for smaller devices, for example, a fan to cool the car while it’s parked in the hot sun,” Loo said.

Here’s a link to and a citation for the paper,

Pairing of near-ultraviolet solar cells with electrochromic windows for smart management of the solar spectrum by Nicholas C. Davy, Melda Sezen-Edmonds, Jia Gao, Xin Lin, Amy Liu, Nan Yao, Antoine Kahn, & Yueh-Lin Loo. Nature Energy 2, Article number: 17104 (2017 doi:10.1038/nenergy.2017.104 Published online: 30 June 2017

This paper is behind a paywall.

Here’s what a sample of the special glass looks like,

Graduate student Nicholas Davy holds a sample of the special window glass. (Photos by David Kelly Crow)