Colorful films could help buildings, cars keep their cool

The cold blast of an air conditioner can be a welcome relief as temperatures soar, but "A/C" units require large amounts of energy and can leak potent greenhouse gases. Today, scientists report an eco-friendly alternative -- a plant-based film that gets cooler when exposed to sunlight and comes in a variety of textures and bright, iridescent colors. The material could someday keep buildings, cars and other structures cool without requiring external power.

The researchers will present their results at the spring meeting of the American Chemical Society (ACS).

"To make materials that remain cooler than the air around them during the day, you need something that reflects a lot of solar light and doesn't absorb it, which would transform energy from the light into heat," says Silvia Vignolini, Ph.D., the project's principal investigator. "There are only a few materials that have this property, and adding color pigments would typically undo their cooling effects," Vignolini adds.

Passive daytime radiative cooling (PDRC) is the ability of a surface to emit its own heat into space without it being absorbed by the air or atmosphere. The result is a surface that, without using any electrical power, can become several degrees colder than the air around it. When used on buildings or other structures, materials that promote this effect can help limit the use of air conditioning and other power-intensive cooling methods.

Some paints and films currently in development can achieve PDRC, but most of them are white or have a mirrored finish, says Qingchen Shen, Ph.D., who is presenting the work at the meeting. Both Vignolini and Shen are at Cambridge University (U.K.). But a building owner who wanted to use a blue-colored PDRC paint would be out of luck -- colored pigments, by definition, absorb specific wavelengths of sunlight and only reflect the colors we see, causing undesirable warming effects in the process.

But there's a way to achieve color without the use of pigments. Soap bubbles, for example, show a prism of different colors on their surfaces. These colors result from the way light interacts with differing thicknesses of the bubble's film, a phenomenon called structural color. Part of Vignolini's research focuses on identifying the causes behind different types of structural colors in nature. In one case, her group found that cellulose nanocrystals (CNCs), which are derived from the cellulose found in plants, could be made into iridescent, colorful films without any added pigment.

As it turns out, cellulose is also one of the few naturally occurring materials that can promote PDRC. Vignolini learned this after hearing a talk from the first researchers to have created a cooling film material. "I thought wow, this is really amazing, and I never really thought cellulose could do this."

In recent work, Shen and Vignolini layered colorful CNC materials with a white-colored material made from ethyl cellulose, producing a colorful bi-layered PDRC film. They made films with vibrant blue, green and red colors that, when placed under sunlight, were an average of nearly 40 F cooler than the surrounding air. A square meter of the film generated over 120 Watts of cooling power, rivaling many types of residential air conditioners. The most challenging aspect of this research, Shen says, was finding a way to make the two layers stick together -- on their own, the CNC films were brittle, and the ethyl cellulose layer had to be plasma-treated to get good adhesion. The result, however, was films that were robust and could be prepared several meters at a time in a standard manufacturing line.

Since creating these first films, the researchers have been improving their aesthetic appearance. Using a method modified from approaches previously explored by the group, they're making cellulose-based cooling films that are glittery and colorful. They've also adjusted the ethyl cellulose film to have different textures, like the differences between types of wood finishes used in architecture and interior design, says Shen. These changes would give people more options when incorporating PDRC effects in their homes, businesses, cars and other structures.

The researchers now plan to find ways they can make their films even more functional. According to Shen, CNC materials can be used as sensors to detect environmental pollutants or weather changes, which could be useful if combined with the cooling power of their CNC-ethyl cellulose films. For example, a cobalt-colored PDRC on a building façade in a car-dense, urban area could someday keep the building cool and incorporate detectors that would alert officials to higher levels of smog-causing molecules in the air.

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We need to learn to live with less steel

Steel is one of the most important materials in the world, integral to the cars we drive, the buildings we inhabit, and the infrastructure that allows us to travel from place to place. Steel is also responsible for 7% of global greenhouse gas emissions. In 2021, 45 countries made a commitment to pursue near-zero-emission steel in the next decade. But how possible is it to produce the steel we need in society with zero emissions?

A new study focused on the Japanese steel industry shows that if we are truly committed to reaching zero emissions, we must be prepared for a scenario where the amount of steel we can produce is lower. Japan has set a target for a 46% reduction in emissions from steel by 2030, and zero emissions by 2050. So far, the roadmap for achieving this relies heavily on future innovations in technology. Hope is held out for developments in carbon capture and storage (CCS) and hydrogen-based technologies.

In the study, Dr. Takuma Watari, a researcher at the National Institute for Environmental Studies, Japan, currently working with the University of Cambridge, argues that there is no silver bullet. He says that current plans to cut carbon emissions underestimate how difficult it will be to develop CCS and hydrogen technologies and deploy them widely: "These technologies still face serious technical, economic, and social challenges, and have yet to be implemented at scale. And importantly, it is highly uncertain whether there will be sufficient non-emitting electricity to use these technologies." We need to confront the possibility that technological innovations might not be ready in time to allow us to maintain current levels of steel production whilst cutting emissions to zero.

The research involved mapping the current flows of steel in Japan's industry and using a model to explore how the industry might change if a strict carbon budget were applied in future. Dr. Watari explains that with current practice, the quantity and quality of steel produced would dramatically decrease under a zero-emission carbon budget. This is because of a lack of resources and the practice of downcycling, in which scraps of steel containing impurities are used to make new products. It is difficult to remove these impurities, so the new products have different quality and functionality from the original steel.

According to Dr. Watari, "zero-emission steel production is possible by 2050, but in limited quantity and quality compared to current total production. This is due to the limited availability of zero-emission compatible resources and downcycling practices of scrap steel."

The research indicates that with a carbon budget of zero emissions, the production of steel goods would be dramatically restricted compared to today, reaching about half the current levels at best. In this case, higher-quality steel production (e.g., sheet steel) would be especially hard hit.

The implication is clear. It is not enough to rely on a technological silver bullet materialising to transform the supply of steel. We also need to look seriously at strategies to reduce demand by shifting our culture of steel use and improving our material efficiency. We also need to pursue upcycling to produce high-grade steel from scrap steel.

This will require collaboration from those who use steel as well as those who produce it. Steel products could be made more resource efficient if they are designed to last longer or to be lightweight. Once steel products reach the end of their life, upcycling could be achieved through advanced sorting and shredding to remove impurities from scrap steel. As a society, Japan may also have to become less steel-dependent and shift to a model of 'service use' rather than ownership of products. Unlike today, when steel is abundant and cheap, a net-zero future will require us to use scarcer, more expensive steel resources with greater efficiency. 

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Computers that power self-driving cars could be a huge driver of global carbon emissions

In the future, the energy needed to run the powerful computers on board a global fleet of autonomous vehicles could generate as many greenhouse gas emissions as all the data centers in the world today.

That is one key finding of a new study from MIT researchers that explored the potential energy consumption and related carbon emissions if autonomous vehicles are widely adopted.

The data centers that house the physical computing infrastructure used for running applications are widely known for their large carbon footprint: They currently account for about 0.3 percent of global greenhouse gas emissions, or about as much carbon as the country of Argentina produces annually, according to the International Energy Agency. Realizing that less attention has been paid to the potential footprint of autonomous vehicles, the MIT researchers built a statistical model to study the problem. They determined that 1 billion autonomous vehicles, each driving for one hour per day with a computer consuming 840 watts, would consume enough energy to generate about the same amount of emissions as data centers currently do.

The researchers also found that in over 90 percent of modeled scenarios, to keep autonomous vehicle emissions from zooming past current data center emissions, each vehicle must use less than 1.2 kilowatts of power for computing, which would require more efficient hardware. In one scenario -- where 95 percent of the global fleet of vehicles is autonomous in 2050, computational workloads double every three years, and the world continues to decarbonize at the current rate -- they found that hardware efficiency would need to double faster than every 1.1 years to keep emissions under those levels.

"If we just keep the business-as-usual trends in decarbonization and the current rate of hardware efficiency improvements, it doesn't seem like it is going to be enough to constrain the emissions from computing onboard autonomous vehicles. This has the potential to become an enormous problem. But if we get ahead of it, we could design more efficient autonomous vehicles that have a smaller carbon footprint from the start," says first author Soumya Sudhakar, a graduate student in aeronautics and astronautics.

Sudhakar wrote the paper with her co-advisors Vivienne Sze, associate professor in the Department of Electrical Engineering and Computer Science (EECS) and a member of the Research Laboratory of Electronics (RLE); and Sertac Karaman, associate professor of aeronautics and astronautics and director of the Laboratory for Information and Decision Systems (LIDS). The research appears in the January-February issue of IEEE Micro.

Modeling emissions

The researchers built a framework to explore the operational emissions from computers on board a global fleet of electric vehicles that are fully autonomous, meaning they don't require a back-up human driver.

The model is a function of the number of vehicles in the global fleet, the power of each computer on each vehicle, the hours driven by each vehicle, and the carbon intensity of the electricity powering each computer.

"On its own, that looks like a deceptively simple equation. But each of those variables contains a lot of uncertainty because we are considering an emerging application that is not here yet," Sudhakar says.

For instance, some research suggests that the amount of time driven in autonomous vehicles might increase because people can multitask while driving and the young and the elderly could drive more. But other research suggests that time spent driving might decrease because algorithms could find optimal routes that get people to their destinations faster.

In addition to considering these uncertainties, the researchers also needed to model advanced computing hardware and software that doesn't exist yet.

To accomplish that, they modeled the workload of a popular algorithm for autonomous vehicles, known as a multitask deep neural network because it can perform many tasks at once. They explored how much energy this deep neural network would consume if it were processing many high-resolution inputs from many cameras with high frame rates, simultaneously.

When they used the probabilistic model to explore different scenarios, Sudhakar was surprised by how quickly the algorithms' workload added up.

For example, if an autonomous vehicle has 10 deep neural networks processing images from 10 cameras, and that vehicle drives for one hour a day, it will make 21.6 million inferences each day. One billion vehicles would make 21.6 quadrillion inferences. To put that into perspective, all of Facebook's data centers worldwide make a few trillion inferences each day (1 quadrillion is 1,000 trillion).

"After seeing the results, this makes a lot of sense, but it is not something that is on a lot of people's radar. These vehicles could actually be using a ton of computer power. They have a 360-degree view of the world, so while we have two eyes, they may have 20 eyes, looking all over the place and trying to understand all the things that are happening at the same time," Karaman says.

Autonomous vehicles would be used for moving goods, as well as people, so there could be a massive amount of computing power distributed along global supply chains, he says. And their model only considers computing -- it doesn't take into account the energy consumed by vehicle sensors or the emissions generated during manufacturing.

Keeping emissions in check

To keep emissions from spiraling out of control, the researchers found that each autonomous vehicle needs to consume less than 1.2 kilowatts of energy for computing. For that to be possible, computing hardware must become more efficient at a significantly faster pace, doubling in efficiency about every 1.1 years.

One way to boost that efficiency could be to use more specialized hardware, which is designed to run specific driving algorithms. Because researchers know the navigation and perception tasks required for autonomous driving, it could be easier to design specialized hardware for those tasks, Sudhakar says. But vehicles tend to have 10- or 20-year lifespans, so one challenge in developing specialized hardware would be to "future-proof" it so it can run new algorithms.

In the future, researchers could also make the algorithms more efficient, so they would need less computing power. However, this is also challenging because trading off some accuracy for more efficiency could hamper vehicle safety.

Now that they have demonstrated this framework, the researchers want to continue exploring hardware efficiency and algorithm improvements. In addition, they say their model can be enhanced by characterizing embodied carbon from autonomous vehicles -- the carbon emissions generated when a car is manufactured -- and emissions from a vehicle's sensors.

While there are still many scenarios to explore, the researchers hope that this work sheds light on a potential problem people may not have considered.

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Passenger car preheating produces as much particulate emissions as driving dozens of kilometers

A new study from Finland, conducted by the University of Eastern Finland and Tampere University, measured particulate emissions from passenger car preheating with an auxiliary heater in sub-zero conditions. The preheating emissions were compared to calculated emissions from driving to determine the driving distance corresponding to the preheating emissions under current emissions standards.

Publishing their findings in Atmospheric Environment: X, the researchers measured auxiliary heater (AH) particulate emissions from the preheating of three gasoline, and three diesel cars for a half an hour period. Preheating was carried out outdoors in sub-zero conditions, i.e., when preheating is recommended by the AH manufacturer.

In terms of particulate emissions, using an auxiliary heater for half an hour was equivalent to a 97-kilometre drive in a gasoline car, or to a 20-kilometre drive in a diesel car, under current emissions standards.

"When driving short distances, vehicle preheating can produce significantly higher particulate emissions than the actual drive, especially when considering that the during-drive emissions of most cars are much lower than the limits set in the emissions standards," says Doctoral Researcher Henri Oikarinen of the University of Eastern Finland.

Auxiliary heaters produce a significant proportion of the preheating emissions on heater start-up and shut-down. This is particularly true for diesel operated heaters, for which steady heating (i.e., not turning the heater on and off) produces less than one third of the preheating emissions. In addition, a significant proportion of the particles produced by auxiliary heaters were observed to be in the smallest nanometric range: more than 50% of the particles produced by gasoline operated heaters, and more than 90% of the particles produced by diesel operated heaters, were in the below 23 nm range.

"However, preheating extends the life cycle of the vehicle and also makes driving more comfortable. These findings do not suggest that people should stop preheating their cars; instead, we could reduce the emissions from preheating by using similar emissions reduction methods that are in place for engine emissions, also for fuel-operated auxiliary heaters. Fuel-operated heaters could also be switched for electric ones," Senior Researcher Panu Karjalainen of Tampere University says.

Current vehicle emissions standards apply to particles above 23 nanometres in size, i.e., the observed large quantity of particles below 23 nanometres in size is significant and raises the question of whether the emissions of these smaller particles, too, should be regulated.

In new cars, an auxiliary heater may be needed also during drive

Fuel-operated auxiliary heaters are used for heating vehicles in cold conditions. Auxiliary heaters are commonly known as 'Webasto' or 'Eberspächer', which are the largest AH manufacturers. Particulate emissions from auxiliary heaters are not regulated by legislation, and research into these emissions is scarce. As a result, the impact of AH emissions on air quality and, consequently, on health and the global emissions budget, remains unknown. However, studying AH emissions is essential to gain an accurate understanding of the total emissions from vehicles.

In recent years, vehicle engine emissions have been significantly reduced by emission after-treatment methods such as particulate filters and carburetors, and by improving engine efficiency. Existing auxiliary heaters, however, do not have similar after-treatment methods that are in place for vehicle engine emissions.

The significance of AH emissions is emphasised especially for certain new vehicle models whose engine performance is so efficient that they do not produce enough heat during the drive in sub-zero conditions. In these cases, an auxiliary heater is needed for heating the vehicle also during the drive.

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Air quality can be better for active commuters than drivers, research shows

New Leicester research has found that people who commute by car can be subject to higher levels of harmful gases than those who walk or cycle to work.

The study, conducted by researchers at the University of Leicester in partnership with Leicester City Council, is published in the Journal of Transport & Health.

Experts found that in-cabin levels of nitrogen dioxide (NO2) -- a key indicator of air quality and harmful when breathed in by humans -- were higher for weekday morning commuters travelling by car, compared to their counterparts travelling by bike or on foot. However, the concentration of fine particulate matter (PM2.5) was shown to be slightly lower for drivers.

Researchers studied four typical routes used by Leicester commuters between city suburbs and the city centre, and used air quality sensors in volunteer walkers' and cyclists' backpacks to measure the concentrations of NO2 and PM2.5. The same devices were also fitted in the cabin of a Nissan Leaf electric vehicle. An electric car was used in order to determine driver exposure to pollutants without interference from the car's own exhaust.

Their findings show that NO2 concentrations can be higher in car cabins (even electric car cabins) than alongside the road where people are walking and cycling. Some PM2.5 can be removed, for example by pollen filters, meaning PM2.5 might be slightly lower in car cabins than alongside the road, but NO2 can be drawn directly into the cabin from the exhaust of traffic in front. This will change as more electric cars come into use, but provides evidence to support the benefits of getting out of a car and walking or cycling instead.

Dr Rikesh Panchal is a Research Associate within the University of Leicester's Centre for Environmental Health and Sustainability, and lead author for the study. He said:

"Anecdotal evidence on public perceptions of air quality during commuting collected by Leicester City Council suggested that people believed that exposure to harmful pollutants was higher for active commuters than for car occupants.

"However, the results of this study show that commuting by car in cities during rush hour can result in larger concentrations of pollutants for people inside the vehicle compared to walkers or cyclists making the same journey. This heightened exposure can have detrimental effects on health.

"Additionally, there are well known health benefits of exercise through walking or cycling. Therefore, policies and incentives that encourage drivers to get out of their car and take up active commuting will benefit many aspects of commuters' health as well as improving the overall air quality of the environment."

The study was conducted in conjunction with Leicester City Council's transport and public health teams. Hannah May, who runs the city council's business engagement programme in the active travel team, helped to set up the research. She said:

"It came out of conversations at our active travel roadshows, which we hold at workplaces to help businesses support their staff with sustainable travel. We were asked how air quality might affect people who travel on foot or by bike in Leicester. I wanted to know what the scientific evidence was.

"Thanks to our partnership with the University of Leicester, I was able to take this idea to them. We carried out 16 weeks of testing and the university came up with the methodology and protocol, and did the data analysis. Together, we've come up with a fascinating piece of research that will help people to make informed choices about the way they choose to travel. We were also able to use the city council's public health expertise to help analyse the benefits of active travel and measure them against the effects of air pollution."

Deputy city mayor for transport and environment, Cllr Adam Clarke, said:

"This strong partnership between the University of Leicester and the city council is providing us with high-quality evidence to support our vision for connected, healthy and green transport for Leicester.

"Leicester has seen big improvements in nitrogen dioxide levels against targets in recent years but there is no such thing as a safe limit. We need to keep improving, not only for the good of our health but for the climate too. This is why our plans to help people make the shift to more sustainable forms of transport are so important and so ambitious."

Read more at Science Daily

From milk protein, a plastic foam that gets better in a tough environment

A new high-performance plastic foam developed from whey proteins can withstand extreme heat better than many common thermoplastics made from petroleum. A research team in Sweden reports that the material, which may be used for example in catalysts for cars, fuel filters or packaging foam, actually improves its mechanical performance after days of exposure to high temperatures.

Reporting in Advanced Sustainable Systems, researchers from KTH Royal Institute of Technology in Stockholm say the research opens the door to using protein-based foam materials in potentially tough environments, such as filtration, thermal insulation and fluid absorption.

The basic building blocks of the material are protein nanofibrils, or PNFs, which are self-assembled from hydrolyzed whey proteins -- a product from cheese-processing -- under specific temperature and pH conditions.

In tests the foams improved with aging. After one month of exposure to a temperature of 150C, the material became stiffer, tougher and stronger, says the study's co-author, Mikael Hedenqvist , professor in the Division of Polymeric Materials at KTH.

"This material only gets stronger with time," he says. "If we compare with petroleum-based, commercial foam materials made of polyethylene and polystyrene, they melt instantly and decompose under the same harsh conditions."

Proteins are often water-soluble, which poses a challenge when developing protein-based materials. Despite this, the material proved water-resistant after the aging process, which polymerized the protein, creating new covalent bonds that stabilized the foams. The foam also resisted even more aggressive substances -- such as surfactants and reducing agents -- that normally decompose or dissolve proteins. The crosslinking also made the foam unaffected by diesel fuel or hot oil.

The material also showed better fire resistance than commonly used polyurethane thermoset.

"This biodegradable, sustainable material can be a viable option for use in aggressive environments where fire resistance is important," Hedenqvist says.

Potential applications include providing support for catalytic metals that operate at higher temperatures, such as platinum catalysts for automobiles. The material could conceivably work as a fuel filter, too.

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Researchers develop tool to aid in development, efficiency of hydrogen-powered cars

Widespread adoption of hydrogen-powered vehicles over traditional electric vehicles requires fuel cells that can convert hydrogen and oxygen safely into water -- a serious implementation problem.

Researchers at the University of Colorado Boulder are addressing one aspect of that roadblock by developing new computational tools and models needed to better understand and manage the conversion process. Hendrik Heinz, an associate professor in the Department of Chemical and Biological Engineering, is leading the effort in partnership with the University of California Los Angeles. His team recently published new findings on the subject in Science Advances.

Fuel cell electric vehicles combine hydrogen in a tank with oxygen taken from the air to produce the electricity needed to run. They don't need to be plugged in to charge and have the added benefit of producing water vapor as a byproduct. Those, plus other factors, have made them an intriguing option in the green and renewable energy transportation areas.

Heinz said a key goal to making the vehicles viable is to find an effective catalyst in the fuel cell that can "burn" the hydrogen with oxygen under controlled conditions needed for safe travel. At the same time, researchers are looking for a catalyst that can do this at near room temperature, with high efficiency and a long lifetime in acidic solution. Platinum metal is commonly used, but predicting the reactions and best materials to use for scaling up or different conditions has been a challenge to date.

"For decades, researchers have struggled to predict the complex processes needed for this work, though enormous progress has been made using nanoplates, nanowires and many other nanostructures," Heinz said. "To address this, we have developed models for metal nanostructures and oxygen, water and metal interactions that exceed the accuracy of current quantum methods by more than 10 times. The models also enable the inclusion of the solvent and dynamics and reveal quantitative correlations between oxygen accessibility to the surface and catalytic activity in the oxygen reduction reaction."

Heinz said the quantitative simulations his team developed show the interaction between oxygen molecules as they encounter different barriers by molecular layers of water on the platinum surface. These interactions make the difference between a slow or fast follow-on reaction and need to be controlled for the process to work efficiently. These reactions happen quite fast -- the conversion into water takes about a millisecond per square nanometer to complete -- and happen on a tiny catalyst surface. All of those variables come together in an intricate, complex "dance" that his team has found a way to model in predictive ways.

The computational and data-intensive methods described in the paper can be used to create designer-nanostructures that would max out the catalytic efficiency, as well as possible surface modifications to further optimize the cost-benefit ratio of fuel cells, Heinz added. His collaborators are exploring the commercial implication of that aspect, and he is applying the tools to help to study a wider range of potential alloys and gain further insights into the mechanics at play.

"The tools described in the paper, especially the interface force field for order-of-magnitude more reliable molecular dynamics simulations, can also be applied to other catalyst and electrocatalyst interfaces for similar groundbreaking and practically useful advances," he said.

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Banning the sale of fossil-fuel cars benefits the climate when replaced by electric cars

If a ban were introduced on the sale of new petrol and diesel cars, and they were replaced by electric cars, the result would be a great reduction in carbon dioxide emissions. That is the finding of new research from Chalmers University of Technology, Sweden, looking at emissions from the entire life cycle -- from manufacture of electric cars and batteries, to electricity used for operation. However, the total effect of a phasing out of fossil-fuelled cars will not be felt until the middle of the century -- and how the batteries are manufactured will affect the extent of the benefit.

A rapid and mandatory phasing in of electric cars could cause emissions from Swedish passenger cars' exhausts to approach zero by 2045. The Swedish government has proposed an outright ban on the sale of new fossil fuel cars from the year 2030 -- but that alone will not be enough to achieve Sweden's climate targets on schedule.

"The lifespan of the cars currently on the roads and those which would be sold before the introduction of such a restriction mean that it would take some time -- around 20 years -- before the full effect becomes visible," says Johannes Morfeldt, researcher in Physical Resource Theory at Chalmers University of Technology and lead author of the recently published scientific study.

To have the desired effect, a ban would either need to be introduced earlier, by the year 2025, or, if the ban is not brought in until 2030, then the use of biofuels in petrol and diesel cars needs to increase significantly before then -- in accordance with the revised Swedish "reduction obligation." The combination of these two measures would have the effect of achieving zero emissions from passenger vehicles and keeping to Sweden's climate targets.

"The results from our study show that rapid electrification of the Swedish car fleet would reduce life cycle emissions, from 14 million tonnes of carbon dioxide in 2020 to between 3 and 5 million tonnes by the year 2045. The end result in 2045 will depend mainly on the extent to which possible emission reductions in the manufacturing industry are realised," says Johannes Morfeldt.

A transition from petrol and diesel cars to electric cars will mean an increased demand for batteries. Batteries for electric cars are often criticised, not least for the fact that they result in high levels of greenhouse gas emissions during manufacture.

"There are relatively good opportunities to reduce emissions from global battery manufacturing. Our review of the literature on this shows that average emissions from global battery manufacturing could decrease by about two thirds per kilowatt hour of battery capacity by the year 2045. However, most battery manufacturing takes place overseas, so Swedish decision-makers have more limited opportunities to influence this question," says Johannes Morfeldt.

From a climate perspective, it does not matter where the emissions take place, and the risk with decisions taken at a national level for lowering passenger-vehicle emissions is that they could lead to increased emissions elsewhere -- a phenomenon sometimes termed 'carbon leakage'. In this case, the increase in emissions would result from greater demand for batteries, and the risk is thus greater the higher the emissions from battery production.

In that case, the Swedish decision would not have as great an effect on reducing the climate impact as desired. The life-cycle emissions would end up in the upper range -- around 5 million tonnes of carbon dioxide instead of around 3 million tonnes. Due to this, there may be reason to regulate emissions in both vehicle and battery production, from a life cycle perspective.

"Within the EU, for example, there is a discussion about setting a common standard for the manufacture of batteries and vehicles -- in a similar way as there is a standard that regulates what may be emitted from exhausts," says Johannes Morfeldt.

But, given Sweden's low emissions from electricity production, a ban on sales of new fossil-fuel cars would indeed result in a sharp reduction of the total climate impact, regardless of how the manufacturing industry develops.

Read more at Science Daily

3D holographic head-up display could improve road safety

Researchers have developed the first LiDAR-based augmented reality head-up display for use in vehicles. Tests on a prototype version of the technology suggest that it could improve road safety by 'seeing through' objects to alert of potential hazards without distracting the driver.

The technology, developed by researchers from the University of Cambridge, the University of Oxford and University College London (UCL), is based on LiDAR (light detection and ranging), and uses LiDAR data to create ultra high-definition holographic representations of road objects which are beamed directly to the driver's eyes, instead of 2D windscreen projections used in most head-up displays.

While the technology has not yet been tested in a car, early tests, based on data collected from a busy street in central London, showed that the holographic images appear in the driver's field of view according to their actual position, creating an augmented reality. This could be particularly useful where objects such as road signs are hidden by large trees or trucks, for example, allowing the driver to 'see through' visual obstructions. The results are reported in the journal Optics Express.

"Head-up displays are being incorporated into connected vehicles, and usually project information such as speed or fuel levels directly onto the windscreen in front of the driver, who must keep their eyes on the road," said lead author Jana Skirnewskaja, a PhD candidate from Cambridge's Department of Engineering. "However, we wanted to go a step further by representing real objects in as panoramic 3D projections."

Skirnewskaja and her colleagues based their system on LiDAR, a remote sensing method which works by sending out a laser pulse to measure the distance between the scanner and an object. LiDAR is commonly used in agriculture, archaeology and geography, but it is also being trialled in autonomous vehicles for obstacle detection.

Using LiDAR, the researchers scanned Malet Street, a busy street on the UCL campus in central London. Co-author Phil Wilkes, a geographer who normally uses LiDAR to scan tropical forests, scanned the whole street using a technique called terrestrial laser scanning. Millions of pulses were sent out from multiple positions along Malet Street. The LiDAR data was then combined with point cloud data, building up a 3D model.

"This way, we can stitch the scans together, building a whole scene, which doesn't only capture trees, but cars, trucks, people, signs, and everything else you would see on a typical city street," said Wilkes. "Although the data we captured was from a stationary platform, it's similar to the sensors that will be in the next generation of autonomous or semi-autonomous vehicles."

When the 3D model of Malet St was completed, the researchers then transformed various objects on the street into holographic projections. The LiDAR data, in the form of point clouds, was processed by separation algorithms to identify and extract the target objects. Another algorithm was used to convert the target objects into computer-generated diffraction patterns. These data points were implemented into the optical setup to project 3D holographic objects into the driver's field of view.

The optical setup is capable of projecting multiple layers of holograms with the help of advanced algorithms. The holographic projection can appear at different sizes and is aligned with the position of the represented real object on the street. For example, a hidden street sign would appear as a holographic projection relative to its actual position behind the obstruction, acting as an alert mechanism.

In future, the researchers hope to refine their system by personalising the layout of the head-up displays and have created an algorithm capable of projecting several layers of different objects. These layered holograms can be freely arranged in the driver's vision space. For example, in the first layer, a traffic sign at a further distance can be projected at a smaller size. In the second layer, a warning sign at a closer distance can be displayed at a larger size.

"This layering technique provides an augmented reality experience and alerts the driver in a natural way," said Skirnewskaja. "Every individual may have different preferences for their display options. For instance, the driver's vital health signs could be projected in a desired location of the head-up display.

"Panoramic holographic projections could be a valuable addition to existing safety measures by showing road objects in real time. Holograms act to alert the driver but are not a distraction."

Read more at Science Daily

Charging electric cars up to 90% in 6 minutes

 With Telsa in the lead, the electric vehicle market is growing around the world. Unlike conventional cars that use internal combustion engines, electric cars are solely powered by lithium ion batteries, so the battery performance defines the car's overall performance. However, slow charging times and weak power are still barriers to be overcome. In light of this, a POSTECH research team has recently developed a faster charging and longer lasting battery material for electric cars.

The research teams of Professor Byoungwoo Kang and Dr. Minkyung Kim of the Department of Materials Science and Engineering at POSTECH and Professor Won-Sub Yoon in the Department of Energy Science at Sungkyunkwan University have together proved for the first time that when charging and discharging Li-ion battery electrode materials, high power can be produced by significantly reducing the charging and discharging time without reducing the particle size. These research findings were published in the recent issue of Energy & Environmental Science, a leading international journal in the energy materials field.

For fast charging and discharging of Li-ion batteries, methods that reduce the particle size of electrode materials were used so far. However, reducing the particle size has a disadvantage of decreasing the volumetric energy density of the batteries.

To this, the research team confirmed that if an intermediate phase in the phase transition is formed during the charging and discharging, high power can be generated without losing high energy density or reducing the particle size through rapid charging and discharging, enabling the development of long-lasting Li-ion batteries.

In the case of phase separating materials that undergo the process of creating and growing new phases while charging and discharging, two phases with different volumes exist within a single particle, resulting in many structural defects in the interface of the two phases. These defects inhibit the rapid growth of a new phase within the particle, hindering quick charging and discharging.

Using the synthesis method developed by the research team, one can induce an intermediate phase that acts as a structural buffer that can dramatically reduce the change in volume between the two phases in a particle.

In addition, it has been confirmed that this buffering intermediate phase can help create and grow a new phase within the particle, improving the speed of insertion and removal of lithium in the particle. This in turn proved that the intermediate phase formation can dramatically increase the charging and discharging speed of the cell by creating a homogenous electrochemical reaction in the electrode where numerous particles is composed of. As a result, the Li-ion battery electrodes synthesized by the research team charge up to 90% in six minutes and discharge 54% in 18 seconds, a promising sign for developing high-power Li-ion batteries.

"The conventional approach has always been a trade-off between its low energy density and the rapid charge and discharge speed due to the reduction in the particle size," remarked Professor Byoungwoo Kang, the corresponding author of the paper. He elaborated, "This research has laid the foundation for developing Li-ion batteries that can achieve quick charging and discharging speed, high energy density, and prolonged performance."

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This beetle can survive getting run over by a car. Engineers are figuring out how

 Getting run over by a car is not a near-death experience for the diabolical ironclad beetle.

How the beetle survives could inspire the development of new materials with the same herculean toughness, engineers show in a paper published Wednesday (Oct. 21) in Nature.

These materials would be stiff but ductile like a paper clip, making machinery such as aircraft gas turbines safer and longer-lasting, the researchers said.

The study, led by engineers at the University of California, Irvine (UCI) and Purdue University, found that the diabolical ironclad beetle's super-toughness lies in its two armorlike "elytron" that meet at a line, called a suture, running the length of the abdomen.

In flying beetles, the elytra protect wings and facilitate flight. But the diabolical ironclad beetle doesn't have wings. Instead, the elytra and connective suture help to distribute an applied force more evenly throughout its body.

"The suture kind of acts like a jigsaw puzzle. It connects various exoskeletal blades -- puzzle pieces -- in the abdomen under the elytra," said Pablo Zavattieri, Purdue's Jerry M. and Lynda T. Engelhardt Professor of Civil Engineering.

This jigsaw puzzle comes to the rescue in several different ways depending on the amount of force applied, Zavattieri said. A video explaining these findings is available on YouTube at https://youtu.be/NS3AqJB5SfU.

To uncover these strategies, a team led by UCI professor David Kisailus first tested the limits of the beetle's exoskeleton and characterized the various structural components involved by looking at CT scans.

Using compressive steel plates, UCI researchers found that the diabolical ironclad beetle can take on an applied force of about 150 newtons -- a load of at least 39,000 times its body weight -- before the exoskeleton begins to fracture.

That's more impressive than sounds: A car tire would apply a force of about 100 newtons if running over the beetle on a dirt surface, the researchers estimate. Other terrestrial beetles the team tested couldn't handle even half the force that a diabolical ironclad can withstand.

Zavattieri's lab followed up these experiments with extensive computer simulations and 3D-printed models that isolated certain structures to better understand their role in saving the beetle's life.

All of these studies combined revealed that when under a compressive load such as a car tire, the diabolical ironclad beetle's jigsaw-like suture offers two lines of defense.

First, the interconnecting blades lock to prevent themselves from pulling out of the suture like puzzle pieces. Second, the suture and blades delaminate, which leads to a more graceful deformation that mitigates catastrophic failure of the exoskeleton. Each strategy dissipates energy to circumvent a fatal impact at the neck, where the beetle's exoskeleton is most likely to fracture.

Even if a maximum force is applied to the beetle's exoskeleton, delamination allows the interconnecting blades to pull out from the suture more gently. If the blades were to interlock too much or too little, the sudden release of energy would cause the beetle's neck to snap.

It's not yet known if the diabolical ironclad beetle has a way to heal itself after surviving a car "accident." But knowing about these strategies could already solve fatigue problems in various kinds of machinery.

"An active engineering challenge is joining together different materials without limiting their ability to support loads. The diabolical ironclad beetle has strategies to circumvent these limitations," said David Restrepo, an assistant professor at the University of Texas at San Antonio who worked on this project as a postdoctoral researcher in Zavattieri's group.

In the gas turbines of aircraft, for example, metals and composite materials are joined together with a mechanical fastener. This fastener adds weight and introduces stress that could lead to fractures and corrosion.

"These fasteners ultimately decrease the performance of the system and need to be replaced every so often. But the interfacial sutures of the diabolical ironclad beetle provide a robust and more predictable failure that could help solve these problems," said Maryam Hosseini, who worked on this project as a Ph.D. student and postdoctoral researcher in Zavattieri's group. Hosseini is now an engineering manager at Procter & Gamble Corp.

UCI researchers built a carbon fiber composite fastener mimicking a diabolical ironclad beetle's suture. Purdue researchers found through loading tests that this fastener is just as strong as a standard aerospace fastener, but significantly tougher.

"This work shows that we may be able to shift from using strong, brittle materials to ones that can be both strong and tough by dissipating energy as they break. That's what nature has enabled the diabolical ironclad beetle to do," Zavattieri said.

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Widespread electric vehicle adoption would save billions of dollars, thousands of lives

 Northwestern University researchers have combined climate modeling with public health data to evaluate the impact of electric vehicles (EVs) on U.S. lives and the economy.

A new study found that if EVs replaced 25% of combustion-engine cars currently on the road, the United States would save approximately $17 billion annually by avoiding damages from climate change and air pollution. In more aggressive scenarios -- replacing 75% of cars with EVs and increasing renewable energy generation -- savings could reach as much as $70 billion annually.

"Vehicle electrification in the United States could prevent hundreds to thousands of premature deaths annually while reducing carbon emissions by hundreds of millions of tons," said Daniel Peters, who led the study. "This highlights the potential of co-beneficial solutions to climate change that not only curb greenhouse gas emissions but also reduce the health burden of harmful air pollution."

"From an engineering and technological standpoint, people have been developing solutions to climate change for years," added Northwestern's Daniel Horton, senior author of the study. "But we need to rigorously assess these solutions. This study presents a nuanced look at EVs and energy generation and found that EV adoption not only reduces greenhouse gases but saves lives."

The study was published online last week (August 13) in the journal GeoHealth.

During this research, Peters was an undergraduate researcher in Horton's laboratory at Northwestern. He now works for the Environmental Defense Fund. Horton is an assistant professor of Earth and planetary sciences in Northwestern's Weinberg College of Arts and Sciences.

To conduct the study, Horton, Peters and their team looked at vehicle fleet and emissions data from 2014. If 25% of U.S. drivers adopted EVs in 2014 -- and the power required to charge their batteries came from 2014's energy generation infrastructure -- then 250 million tons of carbon dioxide (CO2) emissions would have been mitigated. Although the impact of carbon emissions on the climate is well documented, combustion engines also produce other harmful pollutants, such as particulate matter and the precursors to ground-level ozone. Such pollutants can trigger a variety of health problems, including asthma, emphysema, chronic bronchitis and ultimately premature death.

After leaving tailpipes and smokestacks, pollutants interact with their environment, including background chemistry and meteorology.

"A good example is to look at nitrogen oxides (NOx), a group of chemicals produced by fossil-fuel combustion," Peters explained. "NOx itself is damaging to respiratory health, but when it's exposed to sunlight and volatile organic compounds in the atmosphere, ozone and particulate matter can form."

To account for these interactions, the researchers used a chemistry-climate model developed at the Geophysical Fluid Dynamics Laboratory. Jordan Schnell, a postdoctoral fellow in Horton's lab, performed the model experiments that simultaneously simulate the atmosphere's weather and chemistry, including how emissions from combustion engines and power generation sources interact with each other and other emissions sources in their environments.

With this model, the researchers simulated air pollutant changes across the lower 48 states, based on different levels of EV adoption and renewable energy generation. Then, they combined this information with publicly available county health data from the U.S. Environmental Protection Agency (EPA). This combination enabled the research team to assess health consequences from the air quality changes caused by each electrification scenario.

The research team assigned dollar values to the avoided climate and health damages that could be brought about by EV adoption by applying the social cost of carbon and value of statistical life metrics to their emission change results. These commonly used policy tools attach a price tag to long-term health, environmental and agricultural damages.

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