A Massachusetts Institute of Technology (MIT) theoretical study suggests that small changes in roadway paving practices could reduce efficiency loss, potentially eliminating a half-percent of the total greenhouse gas emissions from the transportation sector, at little to no cost.  (One suspects that would also mean a half percent reduction in fuel use.)

Every time you hear a deep rumble and feel your house shake when a big truck roars by, that’s partly because the weight of heavy vehicles causes a slight deflection in the road surface under them. It’s enough of a dip to make a difference to the trucks’ overall fuel efficiency.

The findings are detailed in a paper published in the journal Transportation Research Record, by MIT postdoc Hessam Azarijafari, research scientist Jeremy Gregory, and principal research scientist in the Materials Research Laboratory Randolph Kirchain. The study examined state-by-state data on climate conditions, road lengths, materials properties, and road usage, and modeled different scenarios for pavement resurfacing practices.

Map shows the potential reductions in overall greenhouse gas emissions from the transportation sector, state by state, that could be achieved by policies emphasizing the use of stiffer road surfaces. The greatest potential gains are seen across the southern part of the country. Image Credit: courtesy of the researchers. Massachusetts Institute of Technology. Click image for the largest view.

They found that that one key to improving mileage efficiency is to make pavements that are stiffer, Kirchain explained. That reduces the amount of deflection, which reduces wear on the road but also reduces the slightly uphill motion the vehicle constantly has to make to rise out of its own depression in the road.

Looking to the future, Kirchain noted that while projections show a slight decline in passenger car travel over coming decades, they show an increase in truck travel for freight delivery – the kind where pavement deflection could be a factor in overall efficiency.

There are several ways to make roadways stiffer, the researchers said. One way is to add a very small amount of synthetic fibers or carbon nanotubes to the mix when laying asphalt. Just a tenth of a percent of the inexpensive material could dramatically improve its stiffness, they say. Another way of increasing rigidity is simply to adjust the grading of the different sizes of aggregate used in the mix, to allow for a denser overall mix with more rock and less binder.

“If there are high quality local materials available” to use in the asphalt or concrete mix, “we can use them to improve the stiffness, or we can just adjust the grading of the aggregates that we are using for these pavements,” said Azarijafari. And adding different fibers is “very inexpensive compared to the total cost of the mixture, but it can change the stiffness properties of the mixture significantly.”

Yet another way is to switch from asphalt pavement surfaces to concrete, which has a higher initial cost but is more durable, leading to equal or lower total lifecycle costs. Many road surfaces in northern U.S. states already use concrete, but asphalt is more prevalent in the south. There, it makes even more of a difference, because asphalt is especially subject to deflection in hot weather, whereas concrete surfaces are relatively unaffected by heat. Just upgrading the road surfaces in Texas alone, the study showed, could make a significant impact because of the state’s large network of asphalt roads and its high temperatures.

Kirchain, who is co-director of MIT’s Concrete Sustainability Hub, said that in carrying out this study, the team is “trying to understand what are some of the systemic environmental and economic impacts that are associated with a change to the use of concrete in particular in the pavement system.”

Even though the effects of pavement deflection may seem tiny, he said, “when you take into account the fact that the pavement is going to be there, with thousands of cars driving over it every day, for dozens of years, so a small effect on each one of those vehicles adds up to a significant amount of emissions over the years.” For purposes of this study, they looked at total emissions over the next 50 years and considered the reductions that would be achieved by improving anywhere from 2 percent of road surfaces to 10 percent each year.

With a 10 percent improvement rate, they calculated, a total of 440 megatons of carbon dioxide-equivalent emissions would be avoided over the 50 years, which is about 0.5 percent of total transportation-related emissions for this period.

The proposal may face some challenges, because changing the mix of materials in asphalt might affect its workability in the field, perhaps requiring adjustments to the equipment used. “That change in the field processing would have some cost to it as well,” Kirchain said.

But overall, implementing such changes could in many cases be as simple as changing the specifications required by state or local highway authorities. “These kinds of effects could be considered as part of the performance that’s trying to be managed,” Kirchain said. “It largely would be a choice from the state’s perspective, that either fuel use or climate impact would be something that would be included in the management, as opposed to just the surface performance of the system.”

This research could be a start of something significant. For now a 0.5% gain in efficiency isn’t going to light off a bunch of interest. But that notation of longer life for a roadway could have immense economic effect. Paved roads are expensive, not so noticed as much of the costs are in fuel taxes pre loaded into the pump as the “price.” At today’s gas and diesel prices its a major component of the “price.”

For now with so much focus on CO2 gas, often the real payoff is overlooked in the hope the global warming thing will grab attention. But really, cutting fuel taxes by some noteworthy amount and far longer lasting, less potholes roads is much more likely to seize the attention of road engineers and consumers. “Where might that data be?” we could ask.

A research team led by Kazuhiko Maeda at the Tokyo Institute of Technology has developed a new photocatalyst. They have developed a hybrid material constructed from a metal oxide nanosheet and a light-absorbing molecule for splitting water molecules (H2O) to obtain dihydrogen (H2) under sunlight. Since H2 can be used as carbon-free fuel, this study provides relevant insight towards clean energy generation.

In line with the depletion of fossil fuels and the suggested problems due to their combustion, developing technology for clean energy generation is a topic of global interest.

Among the various methods proposed to generate clean energy, photocatalytic water splitting is showing much promise. This method utilizes solar energy to split water (H2O) molecules and obtain dihydrogen (H2). The H2 can then be used as a carbon-free fuel or as raw material in the production of many important chemicals.

Dye-sensitized H2 evolution using a wide-gap metal oxide. Image Credit: Tokyo Institute of Technology. Click image for the largest view.

The new photocatalyst consists of nanoscale metal oxide sheets and a ruthenium dye molecule, which works according to a mechanism similar to dye-sensitized solar cells. While metal oxides that are photocatalytically active for overall water splitting into H2 and O2 have wide band gaps, dye-sensitized oxides can utilize visible light, the main component of sunlight. The new photocatalyst is capable of generating H2 from water with a turnover frequency of 1960 per hour and an external quantum yield of 2.4%.

These results are the highest recorded for dye-sensitized photocatalysts under visible light, bringing Maeda’s team a step closer to the goal of artificial photosynthesis – replicating the natural process of using water and sunlight to sustainably produce fuel.

The new material, reported in a paper published in the Journal of the American Chemical Society, is constructed from high-surface-area calcium niobate nanosheets (HCa2Nb3O10) intercalated with platinum (Pt) nanoclusters as H2-evolving sites. However, the platinum-modified nanosheets do not work alone, as they do not absorb sunlight efficiently. So a visible light-absorbing ruthenium dye molecule is combined with the nanosheet, enabling solar-driven H2 evolution.

What makes the material efficient is the use of nanosheets, which can be obtained by chemical exfoliation of lamellar HCa2Nb3O10. The high-surface-area and structural flexibility of the nanosheets maximize dye-loadings and density of H2 evolution sites, which in turn improve H2 evolution efficiency. Also, to optimize performance, Maeda’s team modified the nanosheets with amorphous alumina, which plays an important role in improving electron transfer efficiency.

“Unprecedentedly, the alumina modification for nanosheets promotes dye-regeneration during the reaction, without hindering electron injection from the excited-state dye to the nanosheet – the primary step of dye-sensitized H2 evolution,” Maeda said.

“Until just recently, it was considered very difficult to achieve H2 evolution via overall water splitting under visible light using a dye-sensitized photocatalyst with high efficiency,” explained Maeda. “Our new result clearly demonstrates that this is indeed possible, using a carefully designed molecule-nanomaterial hybrid.”

More research still needs to be done, as it will be necessary to further optimize the design of the hybrid photocatalyst to improve the efficiency and long-term durability. Photocatalytic water splitting may be a crucial means of meeting society’s energy demands without further harming the environment, and studies like this one are essential stepping stones to reaching our goal of a greener future.

Its great to see a press release that points out that the research is yielding dihydrogen gas (H2) and not hydrogen gas (H). There is getting to be quite a number of processes and catalysts not rich in super expensive platinum. If the storage issue was worked out hydrogen should have quite a future. That storage matter needs the best, the brightest, most innovative and intuitive minds working at it. Or find the best way lock the hydrogen to some carbon and simply call it good.

University of Houston (UH) and Texas A&M University researchers have reported a structural supercapacitor electrode made from reduced graphene oxide and aramid nanofiber that is stronger and more versatile than conventional carbon-based electrodes.

The explosion of mobile electronic devices, electric vehicles, drones and other technologies have driven demand for new lightweight materials that can provide the power to operate them.

The UH research team also demonstrated that modeling based on the material nanoarchitecture can provide a more accurate understanding of ion diffusion and related properties in the composite electrodes than the traditional modeling method, which is known as the porous media model.

Haleh Ardebili, Bill D. Cook Associate Professor of Mechanical Engineering at UH and corresponding author for a paper describing the work, published in ACS Nano said, “We are proposing that these models based on the nanoarchitecture of the material are more comprehensive, detailed, informative and accurate compared to the porous media model.”

New and more effective nanoarchitectured materials could provide longer battery life and higher energy at a lighter weight. Image Credit: University of Houston. Click image for the largest view.

More accurate modeling methods will help researchers find new and more effective nanoarchitectured materials that can provide longer battery life and higher energy at a lighter weight, she said.

The researchers knew the material tested – reduced graphene oxide and aramid nanofiber, or rGO/ANF – was a good candidate because of its strong electrochemical and mechanical properties. Supercapacitor electrodes are usually made of porous carbon-based materials, which provide efficient electrode performance, Ardebili said.

While the reduced graphene oxide is primarily made of carbon, the aramid nanofiber offers a mechanical strength that increases the electrode’s versatility for a variety of applications, including for the military.

The current paper reflects the researchers’ interest in improving modeling for new energy materials. “We wanted to convey that the conventional models out there, which are porous media-based models, may not be accurate enough for designing these new nanoarchitectured materials and investigating these materials for electrodes or other energy storage devices,” Ardebili said.

That’s because the porous media model generally assumes uniform pore sizes within the material, rather than measuring the varying dimensions and geometric properties of the material.

“What we propose is that yes, the porous media model may be convenient, but it is not necessarily accurate,” Ardebili said. “For state-of-the-art devices, we need more accurate models to better understand and design new electrode materials.”

The work was funded by the U.S. Air Force Office of Scientific Research.

In addition to Ardebili, co-authors include first author Sarah Aderyani and Ali Masoudi, both of UH; and Smit A. Shah, Micah J. Green and Jodie L. Lutkenhaus, all from A&M.

While a first impression might not illuminate the value of this work, handling your cell phone without the battery would make the importance quite clear. Or think of an EV, many of which have a major share of their weight in the batteries. So any electrical weight savings is going to be a substantial benefit. This team’s work should be a significant step forward when costs for the materials come down.

A University of Michigan researcher group has developed a solution that could provide more efficient, more personalized comfort, completely doing away with the wall-mounted thermostats we’re accustomed to.

The study paper describes a Human Embodied Autonomous Thermostat, or “HEAT,” that is detailed in the study published in Building and Environment.

As lockdown requirements ease, COVID-19 is changing the way we use indoor spaces. That presents challenges for those who manage those spaces, from homes to offices and factories.

Not least among these challenges is heating and cooling, which is the largest consumer of energy in American homes and commercial buildings. There’s a need for smarter, more flexible climate control that keeps us comfortable without heating and cooling entire empty buildings.

Image Credit: University of Michigan. Click image for the largest view.

The new system pairs thermal cameras with three-dimensional video cameras to measure whether occupants are hot or cold by tracking their facial temperature. It then feeds the temperature data to a predictive model, which compares it with information about occupants’ thermal preferences.

Finally, the system determines the temperature that will keep the largest number of occupants comfortable with minimum energy expenditure. The new study shows how the system can effectively and efficiently maintain the comfort of 10 occupants in a lab setting.

Project principal investigator and study co-author Carol Menassa, associate professor of civil and environmental engineering said, “COVID presents a variety of new climate control challenges, as buildings are occupied less consistently and people struggle to stay comfortable while wearing masks and other protective gear. HEAT could provide an unobtrusive way to maximize comfort while using less energy. The key innovation here is that we’re able to measure comfort without requiring users to wear any detection devices and without the need for a separate camera for each occupant.”

HEAT works a bit like today’s internet-enabled learning thermostats. When it’s newly installed, occupants teach the system about their preferences by periodically giving it feedback from their smartphones on a three-point scale: “too hot,” “too cold” or “comfortable.” After a few days, HEAT learns their preferences and operates independently.

The research team is working with power company Southern Power to begin testing HEAT in its Alabama offices, where test cameras will be mounted on tripods in the corners of rooms. Menassa explains that cameras would be placed less obtrusively in a permanent installation. The cameras collect temperature data without identifying individuals, and all footage is deleted immediately after processing, usually within a few seconds.

A second test, also with Southern Power, will place the system in an Alabama community of newly constructed smart homes. The team estimates that they could have a residential system on the market within the next five years.

Facial temperature is a good predictor of comfort, Menassa said. When we’re too hot, the blood vessels expand to radiate additional heat, raising facial temperature; when we’re too cold, they constrict, cooling the face. While earlier iterations of the system also used body temperature to predict comfort, they required users to wear wristbands that measured body temperature directly, and to provide frequent feedback about their comfort level.

Study co-author Vineet Kamat, U-M professor of civil and environmental engineering, and electrical engineering and computer science explained further, “The cameras we’re using are common and inexpensive, and the model works very well in a residential context. Internet-enabled thermostats that detect you and learn from you have sort of built a platform for the next phase, where there’s no visible thermostat at all.”

HEAT’s predictive model was built by U-M industrial operations and engineering associate professor Eunshin Byon, who is also an author on the study. She believes that tweaks to the model could make the system useful in applications beyond homes and offices – in hospitals, for example, where care providers struggle to stay comfortable under masks and other protective equipment.

“The COVID-19 pandemic requires nurses and other hospital workers to wear a lot of protective gear, and they’ve struggled to stay comfortable in the fast-faced hospital environment,” Byon said. “The HEAT system could be adapted to help them stay comfortable by adjusting room temperature or even by signaling to them when they need to take a break.”

In partnership with the U-M school of nursing, Menassa’s research group has already conducted a pilot study that explored how the system can be used to provide personalized thermal comfort for nurses working in healthcare environments such as chemotherapy administration units.

This sounds simply grand, a continuous watching intelligence adjusting the temperature to a comfortable level sound truly like the future is coming upon us. If that mean a continuously comfortable temperature that likely saves some money, well, sign your humble writer up!

University of New South Wales (UNSW Sydney) chemical engineers have found a way by making catalysts to convert waste carbon dioxide recycling it into useful industrial products. The process so far has been expensive and complicated – until now. Engineers explain in the press release it’s as easy as playing with Legos. The carbon dioxide can be made into chemical building blocks to make useful industrial products like fuel and plastics.

If validated in an industrial setting and adopted on a large scale, the process could offer another resource as it transitions towards a wider range of chemical and fuel sources.

In a paper published in the journal Advanced Energy Materials, Dr. Rahman Daiyan and Dr. Emma Lovell from UNSW’s School of Chemical Engineering detail a way of creating nanoparticles that promote conversion of waste carbon dioxide into useful industrial components.

Photograph of the high energy XRD cell used for ins-situ measurments. The working electrode is the carbon capillary that contains the ZnO nanomaterials mixed with carbon black, while the counter and reference electrodes were a graphic rod and SCE, respectively. Bulk electrolysis was carried out at different potentials for a duration of 15 minutes under both CO2 and N2 saturated at 0.1 M KHCO3. Image Credit: University of New South Wales. Click image for the largest view.

The researchers, who carried out their work in the Particles and Catalysis Research Laboratory led by Scientia Professor Rose Amal, show that by making zinc oxide at very high temperatures using a technique called flame spray pyrolysis (FSP), they can create nanoparticles which act as the catalyst for turning carbon dioxide into ‘syngas’ – a mix of hydrogen and carbon monoxide used in the manufacture of industrial products. The researchers say this method is cheaper and more scalable to the requirements of heavy industry than what is available today.

Dr. Lovell said, “We used an open flame, which burns at 2000 degrees, to create nanoparticles of zinc oxide that can then be used to convert CO2, using electricity, into syngas. Syngas is often considered the chemical equivalent of a Lego because the two building blocks – hydrogen and carbon monoxide – can be used in different ratios to make things like synthetic diesel, methanol, alcohol or plastics, which are very important industrial precursors. So essentially what we’re doing is converting CO2 into these precursors that can be used to make all these vital industrial chemicals.”

In an industrial setting, an electrolyser containing the FSP-produced zinc oxide particles could be used to convert the waste CO2 into useful permutations of syngas, said Dr. Daiyan. “Waste CO2 from say, a power plant or cement factory, can be passed through this electrolyser, and inside we have our flame-sprayed zinc oxide material in the form of an electrode. When we pass the waste CO2 in, it is processed using electricity and is released from an outlet as syngas in a mix of CO and hydrogen,” he said.

The researchers said in effect, they are closing the carbon loop in industrial processes that create harmful greenhouse gases. And by making small adjustments to the way the nanoparticles are burned by the FSP technique, they can determine the eventual mix of the syngas building blocks produced by the carbon dioxide conversion.

“At the moment you generate syngas by using natural gas – from fossil fuels,” Dr. Daiyan said. “But we’re using waste carbon dioxide and then converting it to syngas in a ratio depending on which industry you want to use it in.”

For example, a one to one ratio between the carbon monoxide and hydrogen lends itself to syngas that can be used as fuel. But a ratio of four parts carbon monoxide and one part hydrogen is suitable for the creation of plastics, Dr. Daiyan explained.

In choosing zinc oxide as their catalyst, the researchers have ensured that their solution has remained a cheaper alternative to what has been previously attempted in this space.

“Past attempts have used expensive materials such as palladium, but this is the first instance where a very cheap and abundant material, mined locally in Australia, has been successfully applied to the problem of waste carbon dioxide conversion,” Dr. Daiyan said.

Dr. Lovell added that what also makes this method appealing is using the FSP flame system to create and control these valuable materials. “It means it can be used industrially, it can be scaled, it’s super quick to make the materials and very effective,” she said. “We don’t need to worry about complicated synthesis techniques that use really expensive metals and precursors – we can burn it and in 10 minutes have these particles ready to go. And by controlling how we burn it, we can control those ratios of desired syngas building blocks.”

While the duo have already built an electrolyser that has been tested with waste CO2 gas that contains contaminants, scaling the technology up to the point where it could convert all of the waste carbon dioxide emitted by a power plant is still a way down the track.

“The idea is that we can take a point source of CO2, such as a coal fired power plant, a gas power plant, or even a natural gas mine where you liberate a huge amount of pure CO2 and we can essentially retrofit this technology at the back end of these plants. Then you could capture that produced CO2 and convert it into something that is hugely valuable to industry,” said Dr Lovell.

The group’s next project will be to test their nanomaterials in a flue gas setting to ensure they are tolerant to the harsh conditions and other chemicals found in industrial waste gas.

This is great news. The idea of recycling CO2 and put the modern economy into a carbon cycle without the planet itself spending thousands or millions of years to get the recycling done would be a boon to the world’s economy and solve the fundamental issue that bedevils those in a state of climate alarm. Looks good sounds good, but we still don’t know the energy costs, investment required and operating expenses. Lets hope these Aussie’s have tiger that will scale with profits to users and low costs materials to consumers.

 


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