University of Maryland researchers have demonstrated a successful prototype of one critical component for affordable small-scale desalination: an inexpensive solar evaporator, made of wood.

About a billion people around the world lack access to safe drinking water. Desalinating salty water into drinkable water can help to fill this dangerous gap. But traditional desalination systems are far too expensive to install and operate in many locations, especially in low-income countries and remote areas.

Steam rises off of a piece of wood under a hot lamp. New UMD research shows wood can form a key part of solar evaporators which use solar energy to turn salt water into drinking water. Image Credit: John T. Consoli, UMD. Click image for the largest view.

Liangbing Hu, associate professor of materials science and engineering and affiliate of the Maryland Energy Innovation Institute explained using wood to make one critical component for affordable small-scale desalination, an inexpensive solar evaporator, the evaporator generates steam with high efficiency and has minimal needs for maintenance.

Hu said the design employs a technique known as interfacial evaporation, “which shows great potential in response to global water scarcity because of its high solar-to-vapor efficiency, low environmental impact, and portable device design with low cost. These features make it suitable for off-grid water generation and purification, especially for low-income countries.”

Interfacial evaporators are made of thin materials that float on saline water. Absorbing solar heat on top, the evaporators continuously pull up the saline water from below and convert it to steam on their top surface, leaving behind the salt, explained Hu, who is senior author on a paper describing the work in Advanced Materials.

But over time salt can build up on this evaporative surface, gradually degrading performance until it is removed, he said.

Hu and his colleagues minimized the need for this maintenance with a device made out of basswood that exploits the wood’s natural structure of the micron-wide channels that carry water and nutrients up the basswood tree.

The researchers supplement these natural channels by drilling a second array of millimeter-wide channels through a thin cross-section of the wood, said Yudi Kuang, a visiting scholar and lead author on the paper. The investigators then briefly expose the top surface to high heat, which carbonizes the surface blackening it for greater solar absorption.

In operation, as the device absorbs solar energy, it draws up salty water through the wood’s natural micron-wide channels. Salt is spontaneously exchanged from these tiny channels through natural openings along their sides to the vastly wider drilled channels, and then easily dissolves back into the water below.

Kuang noted, “In the lab, we have successfully demonstrated excellent anti-fouling in a wide range of salt concentrations, with stable steam generation with about 75% efficiency.”

“Using natural wood as the only starting material, the salt-rejecting solar evaporator is expected to be low-cost,” added research associate Chaoji Chen. The evaporator approach also is effective in other types of wood with similar natural channels. The researchers now are optimizing their system for higher efficiency, lower capital cost, and integration with a steam condenser to complete the desalination cycle.

Hu’s lab also recently developed another solar-heated prototype device that takes advantage of carbonized wood’s ability to absorb and distribute solar energy – this one created to help clean up spills of hard-to-collect heavy oils. “Our carbonized wood material demonstrates rapid and efficient crude oil absorption, as well as low cost and scalable manufacturing potential,” said Kuang, lead author on a paper about the research in Advanced Functional Materials.

“Wood is an intriguing material scaffold, with its unique hierarchically porous structure, and it is a renewable, abundant and cost-effective resource,” Hu said. “In our lab, the fundamental understanding of biomaterials (especially wood) leads us to achieve extraordinary performance that is competitive with widely used but non-sustainable materials.”

Among other projects, his lab has created light and effective “nanowood” insulating materials. It also has engineered “super wood” that is 12 times stronger and 10 times tougher than natural wood, and potentially may replace steel, titanium or carbon fiber in certain applications, he said.

With billions of people in need of safe potable water this kind of innovation is very welcome indeed. One would think coming up with a condenser should be easy enough. That would leave the incentive to get them built distributed and instructions on keeping them clean and safe. No hard or insurmountable problems are obvious.

For the sake of a healthier world population lets hope this technology gets good market legs, and soon.

University of California – Los Angeles (UCLA) researchers have designed a new device that creates electricity from falling snow, a first of a kind thing. The device is inexpensive, small, thin and flexible like a sheet of plastic.

Senior author Richard Kaner, who holds UCLA’s Dr. Myung Ki Hong Endowed Chair in Materials Innovation noted, “The device can work in remote areas because it provides its own power and does not need batteries. It’s a very clever device – a weather station that can tell you how much snow is falling, the direction the snow is falling, and the direction and speed of the wind.”

Thus its practical in a specialized kind of way. Its another way to power things where cold and precipitation occur together.

Boot with device attached. Image Credit: Abdelsalam Ahmed, UCLA. Click image for the largest view.

The researchers call it a snow-based triboelectric nanogenerator, or snow TENG. A triboelectric nanogenerator, which generates charge through static electricity, produces energy from the exchange of electrons.

Findings about the device are published in the journal Nano Energy.

Kaner, who is also a distinguished professor of chemistry and biochemistry, and of materials science and engineering, and a member of the California NanoSystems Institute at UCLA explained, “Static electricity occurs from the interaction of one material that captures electrons and another that gives up electrons. You separate the charges and create electricity out of essentially nothing.”

Snow is positively charged and gives up electrons. Silicone – a synthetic rubber-like material that is composed of silicon atoms and oxygen atoms, combined with carbon, hydrogen and other elements – is negatively charged. When falling snow contacts the surface of silicone, that produces a charge that the device captures, creating electricity.

“Snow is already charged, so we thought, why not bring another material with the opposite charge and extract the charge to create electricity?” said co-author Maher El-Kady, a UCLA postdoctoral researcher of chemistry and biochemistry.

“While snow likes to give up electrons, the performance of the device depends on the efficiency of the other material at extracting these electrons,” he added. “After testing a large number of materials including aluminum foils and Teflon, we found that silicone produces more charge than any other material.”

About 30 percent of the Earth’s surface is covered by snow each winter, during which time solar panels often fail to operate, El-Kady noted. The accumulation of snow reduces the amount of sunlight that reaches the solar array, limiting the panels’ power output and rendering them less effective. The new device could be integrated into solar panels to provide a continuous power supply when it snows, he said.

The device can be used for monitoring winter sports, such as skiing, to more precisely assess and improve an athlete’s performance when running, walking or jumping, Kaner said. It also has the potential for identifying the main movement patterns used in cross-country skiing, which cannot be detected with a smart watch.

It could usher in a new generation of self-powered wearable devices for tracking athletes and their performances.

It can also send signals, indicating whether a person is moving. It can tell when a person is walking, running, jumping or marching.

The research team used 3-D printing to design the device, which has a layer of silicone and an electrode to capture the charge. The team believes the device could be produced at low cost given “the ease of fabrication and the availability of silicone,” Kaner said. Silicone is widely used in industry, in products such as lubricants, electrical wire insulation and biomedical implants, and it now has the potential for energy harvesting.

One point not made really clear is the device is going to need a steady supply of charged snow. Once the snow offloads the charge the device is going to need a fresh shot of snow.

A new Northwestern University study quantified the differences in air pollution generated from battery-powered electric vehicles versus internal combustion engines. The researchers found that even when their electricity is generated from combustion sources, electric vehicles have a net positive impact on air quality and climate change.

The U.S. and other more developed countries with air pollution regulations in effect now for close to 50 years aren’t as attuned to this segment of vehicle electrification. But much of the developing world and most noticeably eastern China have immense health concerns from air pollution where vehicles are part of the source of particulates and noxious gases.

So, if you have ever wondered how much electric vehicle (EV) adoption actually matters for the environment, a new study provides evidence that making this switch would improve overall air quality and lower carbon emissions.

The Northwestern University study quantified the differences in air pollution generated from battery-powered electric vehicles versus internal combustion engines. The researchers found that even when their electricity is generated from combustion sources, electric vehicles have a net positive impact on air quality and climate change.

Northwestern’s Daniel Horton, senior author of the study said, “In contrast to many of the scary climate change impact stories we read in the news, this work is about solutions. We know that climate change is happening, so what can we do about it? One technologically available solution is to electrify our transportation system. We find that EV adoptions reduces net carbon emissions and has the added benefit of reducing air pollutants, thereby improving public health.”

The research has been published in the journal Atmospheric Environment. Horton is an assistant professor of Earth and planetary sciences in Northwestern’s Weinberg College of Arts and Sciences. Jordan Schnell, a postdoctoral research fellow with the Ubben Program for Climate and Carbon Science in the Institute for Sustainability and Energy at Northwestern, was the paper’s first author.

To quantify the differences between the two types of vehicles, the researchers used an emissions remapping algorithm and air quality model simulations. They used these methods to closely examine two pollutants related to automobiles and power emissions: ozone and particulate matter. Both are main components of smog and can trigger a variety of health problems, such as asthma, emphysema and chronic bronchitis.

To fully account for the complexity of changes to air pollution chemistry, the researchers took multiple variables into consideration:
· Potential electric vehicles adoption rates
· Generation of electric vehicle power supply, including our current combustion-dominant mix, combustion-only sources and enhanced emission-free renewables
· Geographical locations
· Seasons and times of day

Ozone levels decreased across the board in simulations of warmer weather months. In the wintertime, however, ozone levels increase slightly but are already much lower compared to summer due to a chemical reaction that occurs differently during times of lesser winter sunlight.
Schnell said, “Across scenarios, we found the more cars that transitioned to electric power, the better for summertime ozone levels. No matter how the power is generated, the more combustion cars you take off the road, the better the ozone quality.”

Particulate matter, which is also called “haze,” decreased in the wintertime but showed greater variation based on location and how the power was generated. Locations with more coal-fired power in their energy mix, for example, experienced an increase in haze during the summer. Locations with clean energy sources, however, saw drastic reductions in human-caused haze.

Schnell continued, “We found that in the Midwest, the increased power demands of EV charging in our current energy mix could cause slight increases in summer particulate matter due to the reliance on coal-fired power generation. However, if we transition more of the Midwest’s power generation to renewables, particulate matter pollution is substantially reduced. In the Pacific Northwester or Northeast, where there is already more clean power available, EV adoption – even with the current energy mix – will decrease particulate matter pollution.”

The photos out of today’s Chinese urban areas with what reminds western baby boomers and older folks looks far worse than what we saw in the LA Basin, the eastern slope of the Rocky Mountains at Denver or even a still day in most any U.S. city of the 1960s.

The U.S. Clean Air Act is one of civilization’s better ideas.

Scientists at Stanford University, the Massachusetts Institute of Technology and the Toyota Research Institute have found how to accurately predict the useful lifespan of lithium-ion batteries, used in devices from mobile phones to electric cars. Its an advance that could accelerate battery development and improve manufacturing.

If manufacturers of cell-phone batteries could tell which cells will last at least two years, then they could sell only those to phone makers and send the rest to makers of less demanding devices. The new research shows how manufacturers could do this. The technique could be used not only to sort manufactured cells but to help new battery designs reach the market more quickly.

Combining comprehensive experimental data and artificial intelligence revealed the key for accurately predicting the useful life of lithium-ion batteries before their capacities start to wane. After the researchers trained their machine learning model with a few hundred million data points of batteries charging and discharging, the algorithm predicted how many more cycles each battery would last, based on voltage declines and a few other factors among the early cycles.

The predictions were within 9 percent of the number of cycles the cells actually lasted. Separately, the algorithm categorized batteries as either long or short life expectancy based on just the first five charge/discharge cycles. Here, the predictions were correct 95 percent of the time.

The research article published in Nature Energy, describes how this machine learning method could accelerate research and development of new battery designs and reduce the time and cost of production, among other applications. The researchers have made the dataset – the largest of its kind – publicly available.

Co-lead author Peter Attia, Stanford doctoral candidate in materials science and engineering said, “The standard way to test new battery designs is to charge and discharge the cells until they fail. Since batteries have a long lifetime, this process can take many months and even years. It’s an expensive bottleneck in battery research.”

The work was carried out at the Center for Data-Driven Design of Batteries, an academic-industrial collaboration that integrates theory, experiments and data science. The Stanford researchers, led by William Chueh, assistant professor in materials science and engineering, conducted the battery experiments. MIT’s team, led by Richard Braatz, professor in chemical engineering, performed the machine learning work. Kristen Severson, co-lead author of the research, completed her doctorate in chemical engineering at MIT last spring.

One focus in the project was to find a better way to charge batteries in 10 minutes, a feature that could accelerate the mass adoption of electric vehicles. To generate the training dataset, the team charged and discharged the batteries until each one reached the end of its useful life, which they defined as capacity loss of 20 percent. En route to optimizing fast charging, the researchers wanted to find out whether it was necessary to run their batteries into the ground. Can the answer to a battery question be found in the information from just the early cycles?

Braatz explained, “Advances in computational power and data generation have recently enabled machine learning to accelerate progress for a variety of tasks. These include prediction of material properties. Our results here show how we can predict the behavior of complex systems far into the future.”

Generally, the capacity of a lithium-ion battery is stable for a while. Then it takes a sharp turn downward. The plummet point varies widely, as most 21st-century consumers know. In this project, the batteries lasted anywhere from 150 to 2,300 cycles. That variation was partly the result of testing different methods of fast charging but also due to manufacturing variability among batteries.

Study co-author Patrick Herring, a scientist at the Toyota Research Institute noted, “For all of the time and money that gets spent on battery development, progress is still measured in decades. In this work, we are reducing one of the most time-consuming steps – battery testing – by an order of magnitude.”

The new method has many potential applications, Attia said. For example, it can shorten the time for validating new types of batteries, which is especially important given rapid advances in materials. With the sorting technique, electric vehicle batteries determined to have short lifespans – too short for cars – could be used instead to power street lights or back up data centers. Recyclers could find cells from used EV battery packs with enough capacity left for a second life.

Yet another possibility is optimizing battery manufacturing. “The last step in manufacturing batteries is called ‘formation,’ which can take days to weeks,” Attia said. “Using our approach could shorten that significantly and lower the production cost.”

The researchers are now using their model to optimize ways of charging batteries in just 10 minutes, which they say will cut the process by more than a factor of 10.

This is definitely welcome technology. If it does get priced low enough to effect lithium ion technology in a large way, an immense improvement would be in place for electrification across the economy. Lithium ion isn’t going to be displaced suddenly, but new chemistries are coming. The list of improvements to lithium ion is impressive, suggesting cutting the months and years needed for testing will speed up new technology adoption. This is Win WIN WIN! technology.

McGill University research shows that it may be possible to create rocket fuel that is much cleaner and safer than the hypergolic fuels that are commonly used today. And still just as effective. The new fuels use simple chemical ‘triggers’ to unlock the energy of one of the hottest new materials, a class of porous solids known as metal-organic frameworks, or MOFs.

The research published this week in Science Advances explores how MOFs are made up of clusters of metal ions and an organic molecule called a linker and may be made into rocket fuel.

Satellites and space stations that remain in orbit for a considerable amount of time rely on hypergols, fuels that are so energetic they will immediately ignite in the presence of an oxidizer (since there is no oxygen to support combustion beyond the Earth’s atmosphere). The hypergolic fuels that are currently mainly in use depend on hydrazine, a highly toxic and dangerously unstable chemical compound made up of a combination of nitrogen and hydrogen atoms. Hydrazine-based fuels are so carcinogenic that people who work with it need to get suited up as though they were preparing for space travel themselves. Despite precautions, around 12,000 tons of hydrazine fuels end up being released into the atmosphere every year by the aerospace industry.

Tomislav Friščić, a professor in the Chemistry Department at McGill, and co-senior author on the paper along with former McGill researcher Robin D. Rogers said, “This is a new, cleaner approach to making highly combustible fuels, that are not only significantly safer than those currently in use, but they also respond or combust very quickly, which is an essential quality in rocket fuel.”

The first author, Hatem Titi, a post-doctoral fellow who works in Friščić’s lab said,
“Although we are still in the early stages of working with these materials in the lab, these results open up the possibility of developing a class of new, clean and highly tunable hypergolic fuels for the aerospace industry.”

Friščić is interested in commercializing this technology, and will work with McGill and Acsynam, an existing spin-off company from his laboratory, to make this happen.

One surely hopes that this technology works out. The article that sources this post is pretty weak on just how nasty hydrazine actually is. The US has been lucky, there hasn’t been a really terrible accident with this stuff. And not dumping 24,000,000 lbs into the sky has a certain appeal as well.


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