GT/ Stronger, stretchier, self-healing plastic
Energy & green technology biweekly vol.60, 3rd November — 17th November
TL;DR
- An innovative plastic, stronger and stretchier than the current standard type and which can be healed with heat, remembers its shape and is partially biodegradable, has been developed. They created it by adding the molecule polyrotaxane to an epoxy resin vitrimer, a type of plastic. Named VPR, the material can hold its form and has strong internal chemical bonds at low temperatures.
- Liquefied stabilized soil (LSS) is made with construction waste and used for filling and backfilling long, confined spaces where traditional compaction is difficult. Using LSS helps speed up construction processes while reducing costs, wastage, and environmental impact. Now, researchers have developed a superior, high-flowability LSS from construction sludge with better mechanical properties and fluidity than conventional LSS, which could make the construction industry more sustainable.
- Formic acid, which can be produced electrochemically from carbon dioxide, is a promising energy carrier. A research team has now developed a fast-charging hybrid battery system that combines the electrochemical generation of formic acid as an energy carrier with a microbial fuel cell. This novel, fast-charging biohybrid battery system can be used to monitor the toxicity of drinking water, just one of many potential future applications.
- As the planet gets hotter, the need for cool living environments is becoming more urgent. But air conditioning is a major contributor to global warming since units use potent greenhouse gases and lots of energy. Now, researchers have found in a new study an inexpensive, sustainable alternative to mechanical cooling with refrigerants in hot and arid climates, and a way to mitigate dangerous heat waves during electricity blackouts.
- Using a new 3D printing technique, researchers have developed special ceramic structures for a solar reactor. Initial experimental testing shows that these structures can boost the production yield of solar fuels.
- The key to bringing global net-zero goals into reach may be algae, say researchers. Studies show the impressive success of certain microalgae varieties in removing CO2 from the atmosphere and then breaking it down into useful materials.
- A new paper revealed that human activities are making Earth’s air, soil, and freshwater saltier, which could pose an ‘existential threat’ if current trends continue. Geologic and hydrologic processes bring salts to Earth’s surface over time, but human activities such as mining and land development are rapidly accelerating this natural ‘salt cycle.’
- As urbanization advances around the globe, the quality of the urban physical environment will become increasingly critical to human well-being and to sustainable development initiatives. However, measuring and tracking the quality of an urban environment, its evolution and its spatial disparities is difficult due to the amount of on-the-ground data needed to capture these patterns.
- A holistic transformation is needed for the planet to accommodate people’s pursuit of well-being. A new study explores a Theory of Planetary Social Pedagogy as a driver of a transformative process based on a learning society.
Green Technology Market
Green technology is an applicable combination of advanced tools and solutions to conserve natural resources and environment, minimize or mitigate negative impacts from human activities on the environment, and ensure sustainability development. Green technology is also referred to as clean technology or environmental technology which includes technologies, such as IoT, AI, analytics, blockchain, digital twin, security, and cloud, which collect, integrate, and analyze data from various real-time data sources, such as sensors, cameras, and Global Positioning System (GPS).
Green technology, also known as sustainable technology, protects the environment by using various forms of sustainable energy. Some of the best examples of green technologies include solar panels, LED lighting, wind energy, electric vehicles, vertical farming, and composting.
The global Green Technology and Sustainability market size to grow from USD 11.2 billion in 2020 to USD 36.6 billion by 2025, at a Compound Annual Growth Rate (CAGR) of 26.6% during the forecast period. The growing consumer and industrial interest for the use of clean energy resources to conserve environment and increasing use of Radio Frequency Identification sensors across industries are driving the adoption of green technology and sustainability solutions and services in the market.
The blockchain segment is estimated to grow at the highest CAGR: Energy-intensive cryptocurrency mining has caused a spike in carbon emission, and hence blockchain is capable of driving innovation in the field of green technology.
Latest Research
Environmentally Friendly Sustainable Thermoset Vitrimer-Containing Polyrotaxane
by Shota Ando, Masaki Hirano, Lisa Watakabe, Hideaki Yokoyama, Kohzo Ito in ACS Materials Letters
An innovative plastic, stronger and stretchier than the current standard type and which can be healed with heat, remembers its shape and partially biodegradable, has been developed by researchers at the University of Tokyo. They created it by adding the molecule polyrotaxane to an epoxy resin vitrimer, a type of plastic. Named VPR, the material can hold its form and has strong internal chemical bonds at low temperatures. However, at temperatures above 150 degrees Celsius, those bonds recombine and the material can be reformed into different shapes. Applying heat and a solvent breaks VPR down into its raw components. Submerging it in seawater for 30 days also resulted in 25% biodegradation, with the polyrotaxane breaking down into a food source for marine life. This new material could have wide-reaching applications for a more circular economy to recirculate resources and reduce waste, from engineering and manufacturing, to medicine and sustainable fashion.
Despite global campaigns to curb plastic use and waste, it is difficult to avoid the ubiquitous material. From toys and clothes, homeware and electronics, to vehicles and infrastructure, nowadays it may seem like it is in almost everything we use. Although useful, there are many issues associated with plastic’s life cycle and disposal. Developing alternatives which last longer, can be reused and recycled more easily, or are made from environmentally friendly sources, is key to helping solve these problems and realize several of the United Nations’ Sustainable Development Goals.
With this in mind, researchers at the University of Tokyo have created a more sustainable plastic, based on an epoxy resin vitrimer. Vitrimers are a relatively new class of plastics, which are solid and strong at lower temperatures (like thermoset plastics, used to make heat-resistant tableware), but which can also be reshaped multiple times at higher temperatures (like thermoplastics, used for plastic bottles). However, they are typically brittle and cannot be stretched far before breaking. By adding a molecule called polyrotaxane, the team was able to create a dramatically improved version which they named VPR (vitrimer incorporated with polyrotaxane [PR]).
“VPR is over fives times as resistant to breaking as a typical epoxy resin vitrimer,” said Project Assistant Professor Shota Ando from the Graduate School of Frontier Sciences. “It also repairs itself 15 times as fast, can recover its original memorized shape twice as fast, and can be chemically recycled 10 times as fast as the typical vitrimer. It even biodegrades safely in a marine environment, which is new for this material.”
Polyrotaxane has been gaining interest in science and industry for its ability to enhance the toughness of different materials. In this study, the improved toughness of VPR meant that more complex shapes could be created and retained even at low temperatures (such as the origami crane in the video provided with this release). Disposal or recycling was also easier than for vitrimers without polyrotaxane, explained Ando:
“Although this resin is insoluble in various solvents at room temperature, it can be easily broken down to the raw material level when immersed in a specific solvent and heated. It also showed 25% biodegradation after exposure to seawater for 30 days. By comparison, vitrimer without PR did not undergo any apparent biodegradation. These characteristics make it an ideal material in today’s society, which demands resource recycling.”
From engineering to fashion, robotics to medicine, the team foresees both practical and playful applications for VPR.
“Just to give some examples, infrastructure materials for roads and bridges are often composed of epoxy resins mixed with compounds such as concrete and carbon. By using VPR, these would be easier to maintain as they would be stronger and healable using heat,” suggested Ando. “Unlike conventional epoxy resins, this new material is hard but stretchable, so it could also be expected to strongly bond materials of different hardness and elongation, such as is needed for vehicle manufacture. Also, as it has shape memory, shape editing and shape recovery capabilities, you might also someday be able to rearrange the silhouette of your favorite clothes at home with a hair dryer or steam iron.”
The team’s next step will be to work with companies to determine the feasibility of its various ideas for VPR, as well as continuing its research in the lab.
“I have always thought that existing plastics are very difficult to recover and dispose of because they are subdivided according to their uses,” said Ando. “It would be ideal if we could solve many of the world’s problems with a single material like this.”
Properties of High-Flowability Liquefied Stabilized Soil Made of Recycled Construction Sludge
by Yuji Shigematsu, Shinya Inazumi, Susit Chaiprakaikeow, Supakij Nontananandh in Recycling
Liquefied stabilized soil (LSS) is made with construction waste and used for filling and backfilling long, confined spaces where traditional compaction is difficult. Using LSS helps speed up construction processes while reducing costs, wastage, and environmental impact. Now, researchers from Shibaura Institute of Technology, Japan have developed a superior, high-flowability LSS from construction sludge with better mechanical properties and fluidity than conventional LSS, which could make the construction industry more sustainable.
The construction industry is a highly resource-intensive and polluting sector, with significant water consumption and notable contribution to environmental degradation. According to a survey conducted by the Ministry of Land, Infrastructure, Transport, and Tourism in 2018, the Japanese construction sector discharged about 74.4 million tons of construction by-products, including 6.2 million tons of construction sludge. In recent years, the construction industry has made efforts to reduce its environmental impact and adopt more sustainable materials and processes. Sustainable construction emphasizes efficient resource utilization, particularly water management; and circularity, wherein construction waste is recycled within the industry.
One such example of circularity in construction is liquified stabilized soil (LSS), which comprises construction-generated soil or construction sludge that is mixed with a solidifier and intermediately treated. LSS is already widely used in construction sites, especially for filling long, narrow spaces where compaction by earthworks is challenging. The utility of LSS as a construction material lies in its flowability, which makes it easily pourable, and its strength after solidifying. LSS exhibits low permeability and high cohesive strength, making this material impervious to groundwater erosion. Moreover, it does not shrink much after casting, and its high adhesion ensures durability during earthquakes. However, despite these favorable properties, there is still scope for improving the characteristics of LSS to further expand its uses and enable more efficient construction practices.
To address this, a group of scientists from Shibaura Institute of Technology (SIT), Japan, and Kasetsart University, Thailand developed a high-flowability LSS (HFLSS) made with construction sludge (HFLSS from RCS) and examined its mechanical properties and flowability through experimental approaches. The team led by Prof. Shinya Inazumi, from the Department of Civil Engineering at SIT, developed their HFLSS using a dewatered solution of very fine clay particles that was derived after dewatering construction sludge. This dewatered solution was blended with ordinary Portland cement as the solidifier.
“Advances in LSS could transform the construction industry and urban development. Urbanization is increasing the demand for space-efficient construction solutions, and LSS and HFLSS made from RCS could be the answer. Their application in tight, challenging spaces could lead to more efficient and sustainable infrastructure projects, while alleviating environmental concerns through the reuse of construction waste,” says Prof. Inazumi.
The results of this experimental study show that HFLSS from RCS exhibits more favorable characteristics than conventional LSS for construction activities. The mechanical properties of HFLSS from RCS are lower than those of conventional LSS, whereas its flow value or flowability is higher than normal LSS (0.54m vs. 0.44m), owing to its lower specific gravity. The high flowability of HFLSS from RCS also results in a lower unconfined compressive strength than conventional LSS (515 kN/m2 vs. 1000 kN/m2). Usually, the unconfined compressive strength required for ordinary backfilling is ≥100–300 kN/m2, suggesting that HFLSS from RCS also meets this requirement.
These results establish HFLSS from RCS as a more efficient and advanced form of LSS extending its applications beyond the usual backfill/filling and road construction. With its high flowability, HFLSS from RCS can fill narrow spaces, such as waste pipes, making it more suitable for use within complex structures. Further, it can also be pumped for distances of 500m and more at lower pressures, decreasing intermediate work and construction time.
“These findings position HFLSS from RCS as a promising sustainable material for large-scale civil engineering projects. Future research on improving this material could revolutionize the construction industry. Overall, its implications are vast — from reduced construction waste and environmental impact, to faster, more efficient urban development, which would benefit economies and promote a sustainable future for generations to come,” concludes Prof. Inazumi.
Super‐fast Charging Biohybrid Batteries through a Power‐to‐formate‐to‐bioelectricity Process by Combining Microbial Electrochemistry and CO2 Electrolysis
by Na Chu, Yong Jiang, Donglin Wang, Daping Li, Raymond Jianxiong Zeng in Angewandte Chemie International Edition
Formic acid, which can be produced electrochemically from carbon dioxide, is a promising energy carrier. A Chinese research team have now developed a fast-charging hybrid battery system that combines the electrochemical generation of formic acid as an energy carrier with a microbial fuel cell. As the team demonstrate in the journal Angewandte Chemie, this novel, fast-charging biohybrid battery system can be used to monitor the toxicity of drinking water, just one of many potential future applications.
Microbial fuel cells harness bacteria to generate electricity, exploiting the ability of some bacterial species to convert energy-rich molecules into electrical energy. In fully microbial batteries, bacteria also produce the energy carrier molecules during the charging process, which are then used to generate electricity during the discharging process. However, one of the disadvantages of fully microbial batteries is that charging is still rather inefficient and slow.
By coupling the purely inorganic electrochemical generation of a biological active molecule with a microbial fuel cell, Yong Jiang’s research team at the Agriculture and Forestry University in Fuzhou, China, and colleagues, have for the first time developed a two-stage hybrid microbial battery system that overcomes many of the challenges faced by fully microbial batteries.
The team also aimed to produce a biohybrid battery using simple and inexpensive components to provide sustainable energy. They found that formic acid is a sustainable biological energy carrier, because it can be produced either biologically or electrocatalytically from carbon dioxide and is then available for consumption by the bacteria in the microbial fuel cell.
Using commercially available components, they designed an electrolysis cell in which inorganic catalysts convert carbon dioxide gas into formic acid. Using this design, the team found that the charging process takes place within a few minutes. Once formic acid has been produced and extracted from the electrolyte, it is fed into a second device — the microbial fuel cell — where bacteria slowly convert it into carbon dioxide and electricity at the bioanode.
This two-stage system produced enough current for 25 hours of discharge, a value that is very useful in many applications. As a proof of concept, the team used the discharge current produced to monitor water for toxins and found that the current signal changed when environmental toxins such as formaldehyde and copper were added to the water. The team suggests further applications in sustainable wastewater treatment or desalination.
Passive radiative cooling to sub-ambient temperatures inside naturally ventilated buildings
by Remy Fortin, Jyotirmoy Mandal, Aaswath P. Raman, Salmaan Craig in Cell Reports Physical Science
As the planet gets hotter, the need for cool living environments is becoming more urgent. But air conditioning is a major contributor to global warming since units use potent greenhouse gases and lots of energy.
Now, researchers from McGill University, UCLA and Princeton have found in a new study an inexpensive, sustainable alternative to mechanical cooling with refrigerants in hot and arid climates, and a way to mitigate dangerous heat waves during electricity blackouts.
The researchers set out to answer how to achieve a new benchmark in passive cooling inside naturally conditioned buildings in hot climates such as Southern California. They examined the use of roof materials that radiate heat into the cold universe, even under direct sunlight, and how to combine them with temperature-driven ventilation. These cool radiator materials and coatings are often used to stop roofs overheating. Researchers have also used them to improve heat rejection from chillers. But there is untapped potential for integrating them into architectural design more fully, so they can not only reject indoor heat to outer space in a passive way, but also drive regular and healthy air changes.
“We found we could maintain air temperatures several degrees below the prevailing ambient temperature, and several degrees more below a reference ‘gold standard’ for passive cooling,” said Remy Fortin, lead author and PhD candidate at the Peter Guo-hua Fu School of Architecture “We did this without sacrificing healthy ventilation air changes.” This was a considerable challenge, considering air exchanges are a source of heating when the aim is to keep a room cooler than the exterior.
The researchers hope the findings will be used to positively impact communities suffering from dangerous climate heating and heat waves.
“We hope that materials scientists, architects, and engineers will be interested in these results, and that our work will inspire more holistic thinking for how to integrate breakthroughs in radiative cooling materials with simple but effective architectural solutions,” said Salmaan Craig, Principal Investigator for the project and Assistant Professor at the Peter Guo-hua Fu School of Architecture.
Solar‐Driven Redox Splitting of CO2 Using 3D‐Printed Hierarchically Channeled Ceria Structures
by Sebastian Sas Brunser, Fabio L. Bargardi, Rafael Libanori, Noëmi Kaufmann, Hugo Braun, Aldo Steinfeld, André R. Studart in Advanced Materials Interfaces
In recent years, engineers at ETH Zurich have developed the technology to produce liquid fuels from sunlight and air. In 2019, they demonstrated the entire thermochemical process chain under real conditions for the first time, in the middle of Zurich, on the roof of ETH Machine Laboratory. These synthetic solar fuels are carbon neutral because they release only as much CO2 during their combustion as was drawn from the air for their production. Two ETH spin-offs, Climeworks and Synhelion, are further developing and commercialising the technologies.
At the heart of the production process is a solar reactor that is exposed to concentrated sunlight delivered by a parabolic mirror and reaches temperatures of up to 1500 degrees Celsius. Inside this reactor, which contains a porous ceramic structure made of cerium oxide, a thermochemical cycle takes place for splitting water and CO2 captured previously from the air. The product is syngas: a mixture of hydrogen and carbon monoxide, which can be further processed into liquid hydrocarbon fuels such as kerosene (jet fuel) for powering aviation.
Until now, structures with isotropic porosity have been applied, but these have the drawback that they exponentially attenuate the incident solar radiation as it travels into the reactor. This results in lower inner temperatures, limiting the fuel yield of the solar reactor.
Now, researchers from the group of André Studart, ETH Professor of Complex Materials, and the group of Aldo Steinfeld, ETH Professor of Renewable Energy Carriers, have developed a novel 3D printing methodology that enables them to manufacture porous ceramic structures with complex pore geometries to transport solar radiation more efficiently into the reactor’s interior. The research project is funded by the Swiss Federal Office of Energy.
Hierarchically ordered designs with channels and pores that are open at the surface exposed to the sunlight and become narrower towards the rear of the reactor have proven to be particularly efficient. This arrangement enables to absorb the incident concentrated solar radiation over the entire volume. This in turn ensures that the whole porous structure reaches the reaction temperature of 1500°C, boosting the fuel generation. These ceramic structures were manufactured using an extrusion-based 3D printing process and a new type of ink with optimal characteristics developed specifically for this purpose, namely: low viscosity and a high concentration of ceria particles to maximise the amount of redox active material.
The researchers investigated the complex interplay between the transfer of radiant heat and the thermochemical reaction. They were able to show that their new hierarchical structures can produce twice as much fuel as the uniform structures when subjected to the same concentrated solar radiation of intensity equivalent to 1000 suns.
The technology for 3D printing the ceramic structures is already patented, and Synhelion has acquired the license from ETH Zurich. “This technology has the potential to boost the solar reactor’s energy efficiency and thus to significantly improve the economic viability of sustainable aviation fuels,” Steinfeld says.
Potential of using microalgae to sequester carbon dioxide and processing to bioproducts
by Venkatesh Balan, James Pierson, Hasan Husain, Sandeep Kumar, Christopher Saffron, Vinod Kumar in Green Chemistry
Scientists may be on the verge of taking a big step closer to the net-zero carbon emissions goal, thanks to University of Houston research into algae. Hidden potential is being revealed in the major algae studies at the microbial products lab, located at UH at Sugar Land.
Venkatesh Balan, associate professor of engineering technology in UH’s Cullen College of Engineering’s Division of Technology, is exploring surprising traits among small fresh- and salt-water phototropic (light-sensitive) organisms referred to as microalgae.
Microalgae can sequester carbon dioxide (CO2) from the atmosphere. But it is its ability, through a series of processes, to convert its captured CO2 into mass-produced proteins, lipids and carbohydrates that most interests Balan and his team of researchers.
“This green process goes beyond climate issues. For example, it may even transform the way we produce our food,” said Balan, who has been studying algae for seven years.
His research evaluates the potential of using microalgae to treat wastewater and use algal biomass to produce food, fertilizers, fuels and chemicals. Algae grown in freshwater treatments, such as spirulina, is being used in health supplements and cosmetics. In the future, microalgae could be used as sustainable feed stock for producing biofuels and biochemicals that could lessen dependency on fossil fuels.
Microalgae’s most immediate superpower, however, is its potential to play a key role in the answer to the worldwide global warming.
“We are experiencing climate change. This summer’s 100-degree heat that lasted three months here in Texas, and in several other parts of the world, had never been seen before. That is a testament to climate change. No one can deny it,” Balan said.
The greenhouse effect — in which certain gases are blanketing Earth’s atmosphere, trapping heat closer to the planet — speeds up the warming. Greenhouse gases can comprise any gas that absorbs infrared radiation. In Earth’s atmosphere, CO2 and chlorofluorocarbon are the main factors.
“There is much interest among lawmakers and policymakers, even among companies that emit greenhouse gases, to find alternatives, especially for those emitted from industry,” Balan said.
But industry cannot be blamed for all the pollution problems that haunt us, he said.
“On your table or in your pantry, you see food products. What’s harder to visualize are the greenhouse gasses emitted by the orchard that grows the fruit, the factory that makes the breakfast cereal, the transportation that brings the cookies to your neighborhood, even your own commute to buy the food. It adds up, but the problem is easy to ignore because we can’t see it. Yet all consumers contribute, in our own way, to the greenhouse effect.”
So, if CO2 and other chemicals are damaging our climate, how do we deal with the excess CO2 in our atmosphere? Until now, most of the scientific world has discussed capturing CO2 and burying it, possibly under an ocean or other large body of water, which is an expensive, energy intensive proposition.
“We are coming up with the alternate approach of using algae to fix the CO2 then using the carbon to make bioproducts that are useful to humankind,” Balan explained.
Balan and his research assistant Masha Alian recently discovered algae can be used as substrate to produce fungus, another useful tool in achieving net zero carbon footprint. The symbiotic relationship between algae and fungi can be found in lichen, which is a composite organism — part algae, part fungi. A common site in rural Texas and elsewhere, lichen (sometimes misnamed tree moss) is a preferred food of deer and other animals that nibble it from the trunks of trees where it grows in the wild.
In Balan’s lab, researchers are trying to mimic how lichen grows in nature. “The algae produce oxygen, and the fungi stabilizes CO2 and produces oxygen,” Balan explained. As a bonus, much of the food bed comprised of algae and fungus could be converted into healthy food products.
The anthropogenic salt cycle
by Sujay S. Kaushal, Gene E. Likens, Paul M. Mayer, Ruth R. Shatkay, Sydney A. Shelton, Stanley B. Grant, Ryan M. Utz, Alexis M. Yaculak, Carly M. Maas, Jenna E. Reimer, Shantanu V. Bhide, Joseph T. Malin, Megan A. Rippy in Nature Reviews Earth & Environment
The planet’s demand for salt comes at a cost to the environment and human health, according to a new scientific review led by University of Maryland Geology Professor Sujay Kaushal. Published in the journal Nature Reviews Earth & Environment, the paper revealed that human activities are making Earth’s air, soil and freshwater saltier, which could pose an “existential threat” if current trends continue.
Geologic and hydrologic processes bring salts to Earth’s surface over time, but human activities such as mining and land development are rapidly accelerating the natural “salt cycle.” Agriculture, construction, water and road treatment, and other industrial activities can also intensify salinization, which harms biodiversity and makes drinking water unsafe in extreme cases.
“If you think of the planet as a living organism, when you accumulate so much salt it could affect the functioning of vital organs or ecosystems,” said Kaushal, who holds a joint appointment in UMD’s Earth System Science Interdisciplinary Center. “Removing salt from water is energy intensive and expensive, and the brine byproduct you end up with is saltier than ocean water and can’t be easily disposed of.”
Kaushal and his co-authors described these disturbances as an “anthropogenic salt cycle,” establishing for the first time that humans affect the concentration and cycling of salt on a global, interconnected scale.
“Twenty years ago, all we had were case studies. We could say surface waters were salty here in New York or in Baltimore’s drinking water supply,” said study co-author Gene Likens, an ecologist at the University of Connecticut and the Cary Institute of Ecosystem Studies. “We now show that it’s a cycle — from the deep Earth to the atmosphere — that’s been significantly perturbed by human activities.”
The new study considered a variety of salt ions that are found underground and in surface water. Salts are compounds with positively charged cations and negatively charged anions, with some of the most abundant ones being calcium, magnesium, potassium and sulfate ions.
“When people think of salt, they tend to think of sodium chloride, but our work over the years has shown that we’ve disturbed other types of salts, including ones related to limestone, gypsum and calcium sulfate,” Kaushal said.
When dislodged in higher doses, these ions can cause environmental problems. Kaushal and his co-authors showed that human-caused salinization affected approximately 2.5 billion acres of soil around the world — an area about the size of the United States. Salt ions also increased in streams and rivers over the last 50 years, coinciding with an increase in the global use and production of salts.
Salt has even infiltrated the air. In some regions, lakes are drying up and sending plumes of saline dust into the atmosphere. In areas that experience snow, road salts can become aerosolized, creating sodium and chloride particulate matter.
Salinization is also associated with “cascading” effects. For example, saline dust can accelerate the melting of snow and harm communities — particularly in the western United States — that rely on snow for their water supply. Because of their structure, salt ions can bind to contaminants in soils and sediments, forming “chemical cocktails” that circulate in the environment and have detrimental effects.
“Salt has a small ionic radius and can wedge itself between soil particles very easily,” Kaushal said. “In fact, that’s how road salts prevent ice crystals from forming.”
Road salts have an outsized impact in the U.S., which churns out 44 billion pounds of the deicing agent each year. Road salts represented 44% of U.S. salt consumption between 2013 and 2017, and they account for 13.9% of the total dissolved solids that enter streams across the country. This can cause a “substantial” concentration of salt in watersheds, according to Kaushal and his co-authors.
To prevent U.S. waterways from being inundated with salt in the coming years, Kaushal recommended policies that limit road salts or encourage alternatives. Washington, D.C., and several other U.S. cities have started treating frigid roads with beet juice, which has the same effect but contains significantly less salt.
Kaushal said it is becoming increasingly important to weigh the short- and long-term risks of road salts, which play an important role in public safety but can also diminish water quality.
“There’s the short-term risk of injury, which is serious and something we certainly need to think about, but there’s also the long-term risk of health issues associated with too much salt in our water,” Kaushal said. “It’s about finding the right balance.”
The study’s authors also called for the creation of a “planetary boundary for safe and sustainable salt use” in much the same way that carbon dioxide levels are associated with a planetary boundary to limit climate change. Kaushal said that while it’s theoretically possible to regulate and control salt levels, it comes with unique challenges.
“This is a very complex issue because salt is not considered a primary drinking water contaminant in the U.S., so to regulate it would be a big undertaking,” Kaushal said. “But do I think it’s a substance that is increasing in the environment to harmful levels? Yes.”
Measuring urban quality and change through the detection of physical attributes of decay
by Andrea Vallebueno, Yong Suk Lee in Scientific Reports
More than two-thirds of the world’s population is expected to live in cities by 2050, according to the United Nations. As urbanization advances around the globe, researchers at the University of Notre Dame and Stanford University said the quality of the urban physical environment will become increasingly critical to human well-being and to sustainable development initiatives.
However, measuring and tracking the quality of an urban environment, its evolution and its spatial disparities is difficult due to the amount of on-the-ground data needed to capture these patterns. To address the issue, Yong Suk Lee, assistant professor of technology, economy and global affairs in the Keough School of Global Affairs at the University of Notre Dame, and Andrea Vallebueno from Stanford University used machine learning to develop a scalable method to measure urban decay at a spatially granular level over time.
“As the world urbanizes, urban planners and policymakers need to make sure urban design and policies adequately address critical issues such as infrastructure and transportation improvements, poverty and the health and safety of urbanites, as well as the increasing inequality within and across cities,” Lee said. “Using machine learning to recognize patterns of neighborhood development and urban inequality, we can help urban planners and policymakers better understand the deterioration of urban space and its importance in future planning.”
Traditionally, the measurement of urban quality and quality of life in urban spaces has used sociodemographic and economic characteristics such as crime rates and income levels, survey data of urbanites’ perception and valued attributes of the urban environment, or image datasets describing the urban space and its socioeconomic qualities. The growing availability of street view images presents new prospects in identifying urban features, Lee said, but the reliability and consistency of these methods across different locations and time remains largely unexplored.
In their study, Lee and Vallebueno used the YOLOv5 model (a form of artificial intelligence that can detect objects) to detect eight object classes that indicate urban decay or contribute to an unsightly urban space — things like potholes, graffiti, garbage, tents, barred or broken windows, discolored or dilapidated façades, weeds and utility markings. They focused on three cities: San Francisco, Mexico City and South Bend, Indiana. They chose neighborhoods in these cities based on factors including urban diversity, stages of urban decay and the authors’ familiarity with the cities.
Using comparative data, they evaluated their method in three contexts: homelessness in the Tenderloin District of San Francisco between 2009 and 2021, a set of small-scale housing projects carried out in 2017 through 2019 in a subset of Mexico City neighborhoods, and the western neighborhoods of South Bend in the 2011 through 2019 period — a part of the city that had been declining for decades but also saw urban revival initiatives.
Researchers found that the trained model could adequately detect the objects it sought across different cities and neighborhoods, and did especially well where there are denser populations, such as San Francisco.
For instance, the maps allowed researchers to assess the temporal and geographic variation in homelessness in the San Francisco area, an issue that has grown over the years.
The model struggled in the more suburban area of South Bend, according to Lee, demonstrating a need to tweak the model and the types of objects identified in less dense populations. In addition, the researchers found there is still a risk for bias that should be addressed.
“Our findings indicate that trained models such as ours are capable of detecting the incidence of decay across different neighborhoods and cities, highlighting the potential of this approach to be scaled in order to track urban quality and change for urban centers across the U.S. and cities in other countries where street view imagery is available,” he said.
Lee said the model has potential to provide valuable information using data that can be collected in a more efficient way compared to using coarser, traditional economic data sources, and that it could be a valuable and timely tool for the government, nongovernmental organizations and the public.
“We found that our approach can employ machine learning to effectively track urban quality and change across multiple cities and urban areas,” Lee said. “This type of data could then be used to inform urban policy and planning and the social issues that are impacted by urbanization, including homelessness.”
A Theory of Planetary Social Pedagogy
by Arto O. Salonen, Erkka Laininen, Juha Hämäläinen, Stephen Sterling in Educational Theory
Escalating planetary crises, including climate change, the depletion of natural resources and the human-induced sixth mass extinction, pose increasing demands on pursuing a good life. As the planet is reaching its limits, old perceptions of well-being are being questioned.
A holistic transformation is needed for the planet to accommodate people’s pursuit of well-being. A new study by an international team of researchers explores a Theory of Planetary Social Pedagogy as a driver of a transformative process based on a learning society.
The Theory of Planetary Social Pedagogy is a way of learning applicable to all societal sectors. According to it, people, societies and the world are an interlinked, systemic entity. Such a worldview can make life meaningful, increase people’s experiences of belonging and inclusion, expand the scope of care, and help people identify their opportunities to influence.
In a time marked by crises, learning to be one with the world is increasingly essential. In many ways, our everyday lives are linked with all other life on Earth. People are constantly connected to their surrounding reality through, for example, the food they eat and the air they breathe.
According to Professor Arto O. Salonen of the University of Eastern Finland, the study’s lead author, the main reason behind the escalating planetary crises is the illusion of people being detached from their surrounding reality.
“As we strive for a comprehensive sustainability transition, we need increasingly robust and more systemic interpretations of reality.”
The current political strategy for a sustainable future emphasises economic and technological progress, but that is not enough. Learning is needed, too. A learning society relies on changes in its citizens’ values, beliefs and worldviews.
“How we become aware of our everyday connection to other people and nature at the level of our emotions, body and mind stands at the core of the sustainability transition,” says Planning Manager Erkka Laininen of the OKKA Foundation for Teaching, Education, and Personal Development, a co-author of the study.
Having an experience of belonging to and being part of the world strengthens people’s sense of meaningfulness and their agency needed in building a sustainable future.
The transformative power of a learning society can be a key factor in the green transformation permeating all society, in which citizens’ consumer behaviour and ways of living, moving and producing food and energy are organised in new ways. Conceptions of work and the economy can be reformed, too.
A sustainable future is not about life becoming more miserable — it’s about life becoming richer and more meaningful as hope for the future grows stronger.
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