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      in Environment

      Study: Carbon-neutral pavements are possible by 2050, but rapid policy and industry action are needed

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      Almost 2.8 million lane-miles, or about 4.6 million lane-kilometers, of the United States are paved.

      Roads and streets form the backbone of our built environment. They take us to work or school, take goods to their destinations, and much more.

      However, a new study by MIT Concrete Sustainability Hub (CSHub) researchers shows that the annual greenhouse gas (GHG) emissions of all construction materials used in the U.S. pavement network are 11.9 to 13.3 megatons. This is equivalent to the emissions of a gasoline-powered passenger vehicle driving about 30 billion miles in a year.

      As roads are built, repaved, and expanded, new approaches and thoughtful material choices are necessary to dampen their carbon footprint. 

      The CSHub researchers found that, by 2050, mixtures for pavements can be made carbon-neutral if industry and governmental actors help to apply a range of solutions — like carbon capture — to reduce, avoid, and neutralize embodied impacts. (A neutralization solution is any compensation mechanism in the value chain of a product that permanently removes the global warming impact of the processes after avoiding and reducing the emissions.) Furthermore, nearly half of pavement-related greenhouse gas (GHG) savings can be achieved in the short term with a negative or nearly net-zero cost.

      The research team, led by Hessam AzariJafari, MIT CSHub’s deputy director, closed gaps in our understanding of the impacts of pavements decisions by developing a dynamic model quantifying the embodied impact of future pavements materials demand for the U.S. road network. 

      The team first split the U.S. road network into 10-mile (about 16 kilometer) segments, forecasting the condition and performance of each. They then developed a pavement management system model to create benchmarks helping to understand the current level of emissions and the efficacy of different decarbonization strategies. 

      This model considered factors such as annual traffic volume and surface conditions, budget constraints, regional variation in pavement treatment choices, and pavement deterioration. The researchers also used a life-cycle assessment to calculate annual state-level emissions from acquiring pavement construction materials, considering future energy supply and materials procurement.

      The team considered three scenarios for the U.S. pavement network: A business-as-usual scenario in which technology remains static, a projected improvement scenario aligned with stated industry and national goals, and an ambitious improvement scenario that intensifies or accelerates projected strategies to achieve carbon neutrality. 

      If no steps are taken to decarbonize pavement mixtures, the team projected that GHG emissions of construction materials used in the U.S. pavement network would increase by 19.5 percent by 2050. Under the projected scenario, there was an estimated 38 percent embodied impact reduction for concrete and 14 percent embodied impact reduction for asphalt by 2050.

      The keys to making the pavement network carbon neutral by 2050 lie in multiple places. Fully renewable energy sources should be used for pavement materials production, transportation, and other processes. The federal government must contribute to the development of these low-carbon energy sources and carbon capture technologies, as it would be nearly impossible to achieve carbon neutrality for pavements without them. 

      Additionally, increasing pavements’ recycled content and improving their design and production efficiency can lower GHG emissions to an extent. Still, neutralization is needed to achieve carbon neutrality.

      Making the right pavement construction and repair choices would also contribute to the carbon neutrality of the network. For instance, concrete pavements can offer GHG savings across the whole life cycle as they are stiffer and stay smoother for longer, meaning they require less maintenance and have a lesser impact on the fuel efficiency of vehicles. 

      Concrete pavements have other use-phase benefits including a cooling effect through an intrinsically high albedo, meaning they reflect more sunlight than regular pavements. Therefore, they can help combat extreme heat and positively affect the earth’s energy balance through positive radiative forcing, making albedo a potential neutralization mechanism.

      At the same time, a mix of fixes, including using concrete and asphalt in different contexts and proportions, could produce significant GHG savings for the pavement network; decision-makers must consider scenarios on a case-by-case basis to identify optimal solutions. 

      In addition, it may appear as though the GHG emissions of materials used in local roads are dwarfed by the emissions of interstate highway materials. However, the study found that the two road types have a similar impact. In fact, all road types contribute heavily to the total GHG emissions of pavement materials in general. Therefore, stakeholders at the federal, state, and local levels must be involved if our roads are to become carbon neutral. 

      The path to pavement network carbon-neutrality is, therefore, somewhat of a winding road. It demands regionally specific policies and widespread investment to help implement decarbonization solutions, just as renewable energy initiatives have been supported. Providing subsidies and covering the costs of premiums, too, are vital to avoid shifts in the market that would derail environmental savings.

      When planning for these shifts, we must recall that pavements have impacts not just in their production, but across their entire life cycle. As pavements are used, maintained, and eventually decommissioned, they have significant impacts on the surrounding environment.

      If we are to meet climate goals such as the Paris Agreement, which demands that we reach carbon-neutrality by 2050 to avoid the worst impacts of climate change, we — as well as industry and governmental stakeholders — must come together to take a hard look at the roads we use every day and work to reduce their life cycle emissions. 

      The study was published in the International Journal of Life Cycle Assessment. In addition to AzariJafari, the authors include Fengdi Guo of the MIT Department of Civil and Environmental Engineering; Jeremy Gregory, executive director of the MIT Climate and Sustainability Consortium; and Randolph Kirchain, director of the MIT CSHub. More

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      in Energy

      A more sustainable way to generate phosphorus

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      Phosphorus is an essential ingredient in thousands of products, including herbicides, lithium-ion batteries, and even soft drinks. Most of this phosphorus comes from an energy-intensive process that contributes significantly to global carbon emissions.

      In an effort to reduce that carbon footprint, MIT chemists have devised an alternative way to generate white phosphorus, a critical intermediate in the manufacture of those phosphorus-containing products. Their approach, which uses electricity to speed up a key chemical reaction, could reduce the carbon emissions of the process by half or even more, the researchers say.

      “White phosphorus is currently an indispensable intermediate, and our process dramatically reduces the carbon footprint of converting phosphate to white phosphorus,” says Yogesh Surendranath, an associate professor of chemistry at MIT and the senior author of the study.

      The new process reduces the carbon footprint of white phosphorus production in two ways: It reduces the temperatures required for the reaction, and it generates significantly less carbon dioxide as a waste product.

      Recent MIT graduate Jonathan “Jo” Melville PhD ’21 and MIT graduate student Andrew Licini are the lead authors of the paper, which appears today in ACS Central Science.

      Purifying phosphorus

      When phosphorus is mined out of the ground, it is in the form of phosphate, a mineral whose basic unit comprises one atom of phosphorus bound to four oxygen atoms. About 95 percent of this phosphate ore is used to make fertilizer. The remaining phosphate ore is processed separately into white phosphorus, a molecule composed of four phosphorus atoms bound to each other. White phosphorus is then fed into a variety of chemical processes that are used to manufacture many different products, such as lithium battery electrolytes and semiconductor dopants.

      Converting those mined phosphates into white phosphorus accounts for a substantial fraction of the carbon footprint of the entire phosphorus industry, Surendranath says. The most energy-intensive part of the process is breaking the bonds between phosphorus and oxygen, which are very stable.

      Using the traditional “thermal process,” those bonds are broken by heating carbon coke and phosphate rock to a temperature of 1,500 degrees Celsius. In this process, the carbon serves to strip away the oxygen atoms from phosphorus, leading to the eventual generation of CO2 as a byproduct. In addition, sustaining those temperatures requires a great deal of energy, adding to the carbon footprint of the process.

      “That process hasn’t changed substantially since its inception over a century ago. Our goal was to figure out how we could develop a process that would substantially lower the carbon footprint of this process,” Surendranath says. “The idea was to combine it with renewable electricity and drive that conversion of phosphate to white phosphorus with electrons rather than using carbon.”

      To do that, the researchers had to come up with an alternative way to weaken the strong phosphorus-oxygen bonds found in phosphates. They achieved this by controlling the environment in which the reaction occurs. The researchers found that the reaction could be promoted using a dehydrated form of phosphoric acid, which contains long chains of phosphate salts held together by bonds called phosphoryl anhydrides. These bonds help to weaken the phosphorus-oxygen bonds.

      When the researchers run an electric current through these salts, electrons break the weakened bonds, allowing the phosphorus atoms to break free and bind to each other to form white phosphorus. At the temperatures needed for this system (about 800 C), phosphorus exists as a gas, so it can bubble out of the solution and be collected in an external chamber.

      Decarbonization

      The electrode that the researchers used for this demonstration relies on carbon as a source of electrons, so the process generates some carbon dioxide as a byproduct. However, they are now working on swapping that electrode out for one that would use phosphate itself as the electron source, which would further reduce the carbon footprint by cleanly separating phosphate into phosphorus and oxygen.

      With the process reported in this paper, the researchers have reduced the overall carbon footprint for generating white phosphorus by about 50 percent. With future modifications, they hope to bring the carbon emissions down to nearly zero, in part by using renewable energy such as solar or wind power to drive the electric current required.

      If the researchers succeed in scaling up their process and making it widely available, it could allow industrial users to generate white phosphorus on site instead of having it shipped from the few places in the world where it is currently manufactured. That would cut down on the risks of transporting white phosphorus, which is an explosive material.

      “We’re excited about the prospect of doing on-site generation of this intermediate, so you don’t have to do the transportation and distribution,” Surendranath says. “If you could decentralize this production, the end user could make it on site and use it in an integrated fashion.”

      In order to do this study, the researchers had to develop new tools for controlling the electrolytes (such as salts and acids) present in the environment, and for measuring how those electrolytes affect the reaction. Now, they plan to use the same approach to try to develop lower-carbon processes for isolating other industrially important elements, such as silicon and iron.

      “This work falls within our broader interests in decarbonizing these legacy industrial processes that have a huge carbon footprint,” Surendranath says. “The basic science that leads us there is understanding how you can tailor the electrolytes to foster these processes.”

      The research was funded by the UMRP Partnership for Progress on Sustainable Development in Africa, a fellowship from the MIT Tata Center for Technology and Design, and a National Defense Science and Engineering Graduate Fellowship. More

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      in Environment

      Rescuing small plastics from the waste stream

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      As plastic pollution continues to mount, with growing risks to ecosystems and wildlife, manufacturers are beginning to make ambitious commitments to keep new plastics out of the environment. A growing number have signed onto the U.S. Plastics Pact, which pledges to make 100 percent of plastic packaging reusable, recyclable, or compostable, and to see 50 percent of it effectively recycled or composted, by 2025.

      But for companies that make large numbers of small, disposable plastics, these pocket-sized objects are a major barrier to realizing their recycling goals.

      “Think about items like your toothbrush, your travel-size toothpaste tubes, your travel-size shampoo bottles,” says Alexis Hocken, a second-year PhD student in the MIT Department of Chemical Engineering. “They end up actually slipping through the cracks of current recycling infrastructure. So you might put them in your recycling bin at home, they might make it all the way to the sorting facility, but when it comes down to actually sorting them, they never make it into a recycled plastic bale at the very end of the line.”

      Now, a group of five consumer products companies is working with MIT to develop a sorting process that can keep their smallest plastic products inside the recycling chain. The companies — Colgate-Palmolive, Procter & Gamble, the Estée Lauder Companies, L’Oreal, and Haleon — all manufacture a large volume of “small format” plastics, or products less than two inches long in at least two dimensions. In a collaboration with Brad Olsen, the Alexander and I. Michael Kasser (1960) Professor of Chemical Engineering; Desiree Plata, an associate professor of civil and environmental engineering; the MIT Environmental Solutions Initiative; and the nonprofit The Sustainability Consortium, these companies are seeking a prototype sorting technology to bring to recycling facilities for large-scale testing and commercial development.

      Working in Olsen’s lab, Hocken is coming to grips with the complexity of the recycling systems involved. Material recovery facilities, or MRFs, are expected to handle products in any number of shapes, sizes, and materials, and sort them into a pure stream of glass, metal, paper, or plastic. Hocken’s first step in taking on the recycling project was to tour one of these MRFs in Portland, Maine, with Olsen and Plata.

      “We could literally see plastics just falling from the conveyor belts,” she says. “Leaving that tour, I thought, my gosh! There’s so much improvement that can be made. There’s so much impact that we can have on this industry.”

      From designing plastics to managing them

      Hocken always knew she wanted to work in engineering. Growing up in Scottsdale, Arizona, she was able to spend time in the workplace with her father, an electrical engineer who designs biomedical devices. “Seeing him working as an engineer, and how he’s solving these really important problems, definitely sparked my interest,” she says. “When it came time to begin my undergraduate degree, it was a really easy decision to choose engineering after seeing the day-to-day that my dad was doing in his career.”

      At Arizona State University, she settled on chemical engineering as a major and began working with polymers, coming up with combinations of additives for 3D plastics printing that could help fine-tune how the final products behaved. But even working with plastics every day, she rarely thought about the implications of her work for the environment.

      “And then in the spring of my final year at ASU, I took a class about polymers through the lens of sustainability, and that really opened my eyes,” Hocken remembers. The class was taught by Professor Timothy Long, director of the Biodesign Center for Sustainable Macromolecular Materials and Manufacturing and a well-known expert in the field of sustainable plastics. “That first session, where he laid out all of the really scary facts surrounding the plastics crisis, got me very motivated to look more into that field.”

      At MIT the next year, Hocken sought out Olsen as her advisor and made plastics sustainability her focus from the start.

      “Coming to MIT was my first time venturing outside of the state of Arizona for more than a three-month period,” she says. “It’s been really fun. I love living in Cambridge and the Boston area. I love my labmates. Everyone is so supportive, whether it’s to give me advice about some science that I’m trying to figure out, or just give me a pep talk if I’m feeling a little discouraged.”

      A challenge to recycle

      A lot of plastics research today is devoted to creating new materials — including biodegradable ones that are easier for natural ecosystems to absorb, and highly recyclable ones that hold their properties better after being melted down and recast.

      But Hocken also sees a huge need for better ways to handle the plastics we’re already making. “While biodegradable and sustainable polymers represent a very important route, and I think they should certainly be further pursued, we’re still a ways away from that being a reality universally across all plastic packaging,” she says. As long as large volumes of conventional plastic are coming out of factories, we’ll need innovative ways to stop it from piling onto the mountain of plastic pollution. In one of her projects, Hocken is trying to come up with new uses for recycled plastic that take advantage of its lost strength to produce a useful, flexible material similar to rubber.

      The small-format recycling project also falls in this category. The companies supporting the project have challenged the MIT team to work with their products exactly as currently manufactured — especially because their competitors use similar packaging materials that will also need to be covered by any solution the MIT team devises.

      The challenge is a large one. To kick the project off, the participating companies sent the MIT team a wide range of small-format products that need to make it through the sorting process. These include containers for lip balm, deodorant, pills, and shampoo, and disposable tools like toothbrushes and flossing picks. “A constraint, or problem I foresee, is just how variable the shapes are,” says Hocken. “A flossing pick versus a toothbrush are very different shapes.”

      Nor are they all made of the same kind of plastic. Many are made of polyethylene terephthalate (PET, type 1 in the recycling label system) or high-density polyethylene (HDPE, type 2), but nearly all of the seven recycling categories are represented among the sample products. The team’s solution will have to handle them all.

      Another obstacle is that the sorting process at a large MRF is already very complex and requires a heavy investment in equipment. The waste stream typically goes through a “glass breaker screen” that shatters glass and collects the shards; a series of rotating rubber stars to pull out two-dimensional objects, collecting paper and cardboard; a system of magnets and eddy currents to attract or repel different metals; and finally, a series of optical sorters that use infrared spectroscopy to identify the various types of plastics, then blow them down different chutes with jets of air. MRFs won’t be interested in adopting additional sorters unless they’re inexpensive and easy to fit into this elaborate stream.

      “We’re interested in creating something that could be retrofitted into current technology and current infrastructure,” Hocken says.

      Shared solutions

      “Recycling is a really good example of where pre-competitive collaboration is needed,” says Jennifer Park, collective action manager at The Sustainability Consortium (TSC), who has been working with corporate stakeholders on small format recyclability and helped convene the sponsors of this project and organize their contributions. “Companies manufacturing these products recognize that they cannot shift entire systems on their own. Consistency around what is and is not recyclable is the only way to avoid confusion and drive impact at scale.

      “Additionally, it is interesting that consumer packaged goods companies are sponsoring this research at MIT which is focused on MRF-level innovations. They’re investing in innovations that they hope will be adopted by the recycling industry to make progress on their own sustainability goals.”

      Hocken believes that, despite the challenges, it’s well worth pursuing a technology that can keep small-format plastics from slipping through MRFs’ fingers.

      “These are products that would be more recyclable if they were easier to sort,” she says. “The only thing that’s different is the size. So you can recycle both your large shampoo bottle and the small travel-size one at home, but the small one isn’t guaranteed to make it into a plastic bale at the end. If we can come up with a solution that specifically targets those while they’re still on the sorting line, they’re more likely to end up in those plastic bales at the end of the line, which can be sold to plastic reclaimers who can then use that material in new products.”

      “TSC is really excited about this project and our collaboration with MIT,” adds Park. “Our project stakeholders are very dedicated to finding a solution.”

      To learn more about this project, contact Christopher Noble, director of corporate engagement at the MIT Environmental Solutions Initiative. More

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      in Environment

      Chess players face a tough foe: air pollution

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      Here’s something else chess players need to keep in check: air pollution.

      That’s the bottom line of a newly published study co-authored by an MIT researcher, showing that chess players perform objectively worse and make more suboptimal moves, as measured by a computerized analysis of their games, when there is more fine particulate matter in the air.

      More specifically, given a modest increase in fine particulate matter, the probability that chess players will make an error increases by 2.1 percentage points, and the magnitude of those errors increases by 10.8 percent. In this setting, at least, cleaner air leads to clearer heads and sharper thinking.

      “We find that when individuals are exposed to higher levels of air pollution, they make more more mistakes, and they make larger mistakes,” says Juan Palacios, an economist in MIT’s Sustainable Urbanization Lab, and co-author of a newly published paper detailing the study’s findings.

      The paper, “Indoor Air Quality and Strategic Decision-Making,” appears today in advance online form in the journal Management Science. The authors are Steffen Künn, an associate professor in the School of Business and Economics at Maastricht University, the Netherlands; Palacios, who is head of research in the Sustainable Urbanization Lab, in MIT’s Department of Urban Studies and Planning (DUSP); and Nico Pestel, an associate professor in the School of Business and Economics at Maastricht University.

      The toughest foe yet?

      Fine particulate matter refers to tiny particles 2.5 microns or less in diameter, notated as PM2.5. They are often associated with burning matter — whether through internal combustion engines in autos, coal-fired power plants, forest fires, indoor cooking through open fires, and more. The World Health Organization estimates that air pollution leads to over 4 million premature deaths worldwide every year, due to cancer, cardiovascular problems, and other illnesses.

      Scholars have produced many studies exploring the effects of air pollution on cognition. The current study adds to that literature by analyzing the subject in a particularly controlled setting. The researchers studied the performance of 121 chess players in three seven-round tournaments in Germany in 2017, 2018, and 2019, comprising more than 30,000 chess moves. The scholars used three web-connected sensors inside the tournament venue to measure carbon dioxide, PM2.5 concentrations, and temperature, all of which can be affected by external conditions, even in an indoor setting. Because each tournament lasted eight weeks, it was possible to examine how air-quality changes related to changes in player performance.

      In a replication exercise, the authors found the same impacts of air pollution on some of the strongest players in the history of chess using data from 20 years of games from the first division of the German chess league. 

      To evaluate the matter of performance of players, meanwhile, the scholars used software programs that assess each move made in each chess match, identify optimal decisions, and flag significant errors.

      During the tournaments, PM2.5 concentrations ranged from 14 to 70 micrograms per cubic meter of air, levels of exposure commonly found in cities in the U.S. and elsewhere. The researchers examined and ruled out alternate potential explanations for the dip in player performance, such as increased noise. They also found that carbon dioxide and temperature changes did not correspond to performance changes. Using the standardized ratings chess players earn, the scholars also accounted for the quality of opponents each player faced. Ultimately, the analysis using the plausibly random variation in pollution driven by changes in wind direction confirms that the findings are driven by the direct exposure to air particles.

      “It’s pure random exposure to air pollution that is driving these people’s performance,” Palacios says. “Against comparable opponents in the same tournament round, being exposed to different levels of air quality makes a difference for move quality and decision quality.”

      The researchers also found that when air pollution was worse, the chess players performed even more poorly when under time constraints. The tournament rules mandated that 40 moves had to be made within 110 minutes; for moves 31-40 in all the matches, an air pollution increase of 10 micrograms per cubic meter led to an increased probability of error of 3.2 percent, with the magnitude of those errors increasing by 17.3 percent.

      “We find it interesting that those mistakes especially occur in the phase of the game where players are facing time pressure,” Palacios says. “When these players do not have the ability to compensate [for] lower cognitive performance with greater deliberation, [that] is where we are observing the largest impacts.”

      “You can live miles away and be affected”

      Palacios emphasizes that, as the study indicates, air pollution may affect people in settings where they might not think it makes a difference.

      “It’s not like you have to live next to a power plant,” Palacios says. “You can live miles away and be affected.”

      And while the focus of this particular study is tightly focused on chess players, the authors write in the paper that the findings have “strong implications for high-skilled office workers,” who might also be faced with tricky cognitive tasks in conditions of variable air pollution. In this sense, Palacios says, “The idea is to provide accurate estimates to policymakers who are making difficult decisions about cleaning up the environment.”

      Indeed, Palacios observes, the fact that even chess players — who spend untold hours preparing themselves for all kinds of scenarios they may face in matches — can perform worse when air pollution rises suggests that a similar problem could affect people cognitively in many other settings.

      “There are more and more papers showing that there is a cost with air pollution, and there is a cost for more and more people,” Palacios says. “And this is just one example showing that even for these very [excellent] chess players, who think they can beat everything — well, it seems that with air pollution, they have an enemy who harms them.”

      Support for the study was provided, in part, by the Graduate School of Business and Economics at Maastricht, and the Institute for Labor Economics in Bonn, Germany. More

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      in Energy

      A healthy wind

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      Nearly 10 percent of today’s electricity in the United States comes from wind power. The renewable energy source benefits climate, air quality, and public health by displacing emissions of greenhouse gases and air pollutants that would otherwise be produced by fossil-fuel-based power plants.

      A new MIT study finds that the health benefits associated with wind power could more than quadruple if operators prioritized turning down output from the most polluting fossil-fuel-based power plants when energy from wind is available.

      In the study, published today in Science Advances, researchers analyzed the hourly activity of wind turbines, as well as the reported emissions from every fossil-fuel-based power plant in the country, between the years 2011 and 2017. They traced emissions across the country and mapped the pollutants to affected demographic populations. They then calculated the regional air quality and associated health costs to each community.

      The researchers found that in 2014, wind power that was associated with state-level policies improved air quality overall, resulting in $2 billion in health benefits across the country. However, only roughly 30 percent of these health benefits reached disadvantaged communities.

      The team further found that if the electricity industry were to reduce the output of the most polluting fossil-fuel-based power plants, rather than the most cost-saving plants, in times of wind-generated power, the overall health benefits could quadruple to $8.4 billion nationwide. However, the results would have a similar demographic breakdown.

      “We found that prioritizing health is a great way to maximize benefits in a widespread way across the U.S., which is a very positive thing. But it suggests it’s not going to address disparities,” says study co-author Noelle Selin, a professor in the Institute for Data, Systems, and Society and the Department of Earth, Atmospheric and Planetary Sciences at MIT. “In order to address air pollution disparities, you can’t just focus on the electricity sector or renewables and count on the overall air pollution benefits addressing these real and persistent racial and ethnic disparities. You’ll need to look at other air pollution sources, as well as the underlying systemic factors that determine where plants are sited and where people live.”

      Selin’s co-authors are lead author and former MIT graduate student Minghao Qiu PhD ’21, now at Stanford University, and Corwin Zigler at the University of Texas at Austin.

      Turn-down service

      In their new study, the team looked for patterns between periods of wind power generation and the activity of fossil-fuel-based power plants, to see how regional electricity markets adjusted the output of power plants in response to influxes of renewable energy.

      “One of the technical challenges, and the contribution of this work, is trying to identify which are the power plants that respond to this increasing wind power,” Qiu notes.

      To do so, the researchers compared two historical datasets from the period between 2011 and 2017: an hour-by-hour record of energy output of wind turbines across the country, and a detailed record of emissions measurements from every fossil-fuel-based power plant in the U.S. The datasets covered each of seven major regional electricity markets, each market providing energy to one or multiple states.

      “California and New York are each their own market, whereas the New England market covers around seven states, and the Midwest covers more,” Qiu explains. “We also cover about 95 percent of all the wind power in the U.S.”

      In general, they observed that, in times when wind power was available, markets adjusted by essentially scaling back the power output of natural gas and sub-bituminous coal-fired power plants. They noted that the plants that were turned down were likely chosen for cost-saving reasons, as certain plants were less costly to turn down than others.

      The team then used a sophisticated atmospheric chemistry model to simulate the wind patterns and chemical transport of emissions across the country, and determined where and at what concentrations the emissions generated fine particulates and ozone — two pollutants that are known to damage air quality and human health. Finally, the researchers mapped the general demographic populations across the country, based on U.S. census data, and applied a standard epidemiological approach to calculate a population’s health cost as a result of their pollution exposure.

      This analysis revealed that, in the year 2014, a general cost-saving approach to displacing fossil-fuel-based energy in times of wind energy resulted in $2 billion in health benefits, or savings, across the country. A smaller share of these benefits went to disadvantaged populations, such as communities of color and low-income communities, though this disparity varied by state.

      “It’s a more complex story than we initially thought,” Qiu says. “Certain population groups are exposed to a higher level of air pollution, and those would be low-income people and racial minority groups. What we see is, developing wind power could reduce this gap in certain states but further increase it in other states, depending on which fossil-fuel plants are displaced.”

      Tweaking power

      The researchers then examined how the pattern of emissions and the associated health benefits would change if they prioritized turning down different fossil-fuel-based plants in times of wind-generated power. They tweaked the emissions data to reflect several alternative scenarios: one in which the most health-damaging, polluting power plants are turned down first; and two other scenarios in which plants producing the most sulfur dioxide and carbon dioxide respectively, are first to reduce their output.

      They found that while each scenario increased health benefits overall, and the first scenario in particular could quadruple health benefits, the original disparity persisted: Communities of color and low-income communities still experienced smaller health benefits than more well-off communities.

      “We got to the end of the road and said, there’s no way we can address this disparity by being smarter in deciding which plants to displace,” Selin says.

      Nevertheless, the study can help identify ways to improve the health of the general population, says Julian Marshall, a professor of environmental engineering at the University of Washington.

      “The detailed information provided by the scenarios in this paper can offer a roadmap to electricity-grid operators and to state air-quality regulators regarding which power plants are highly damaging to human health and also are likely to noticeably reduce emissions if wind-generated electricity increases,” says Marshall, who was not involved in the study.

      “One of the things that makes me optimistic about this area is, there’s a lot more attention to environmental justice and equity issues,” Selin concludes. “Our role is to figure out the strategies that are most impactful in addressing those challenges.”

      This work was supported, in part, by the U.S. Environmental Protection Agency, and by the National Institutes of Health. More

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      in Environment

      MIT PhD students shed light on important water and food research

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      One glance at the news lately will reveal countless headlines on the dire state of global water and food security. Pollution, supply chain disruptions, and the war in Ukraine are all threatening water and food systems, compounding climate change impacts from heat waves, drought, floods, and wildfires.

      Every year, MIT’s Abdul Latif Jameel Water and Food Systems Lab (J-WAFS) offers fellowships to outstanding MIT graduate students who are working on innovative ways to secure water and food supplies in light of these urgent worldwide threats. J-WAFS announced this year’s fellowship recipients last April. Aditya Ghodgaonkar and Devashish Gokhale were awarded Rasikbhai L. Meswani Fellowships for Water Solutions, which are made possible by a generous gift from Elina and Nikhil Meswani and family. James Zhang, Katharina Fransen, and Linzixuan (Rhoda) Zhang were awarded J-WAFS Fellowships for Water and Food Solutions. The J-WAFS Fellowship for Water and Food Solutions is funded in part by J-WAFS Research Affiliate companies: Xylem, Inc., a water technology company, and GoAigua, a company leading the digital transformation of the water industry.

      The five fellows were each awarded a stipend and full tuition for one semester. They also benefit from mentorship, networking connections, and opportunities to showcase their research.

      “This year’s cohort of J-WAFS fellows show an indefatigable drive to explore, create, and push back boundaries,” says John H. Lienhard, director of J-WAFS. “Their passion and determination to create positive change for humanity are evident in these unique video portraits, which describe their solutions-oriented research in water and food,” Lienhard adds.

      J-WAFS funder Community Jameel recently commissioned video portraitures of each student that highlight their work and their inspiration to solve challenges in water and food. More about each J-WAFS fellow and their research follows.

      Play video

      Katharina Fransen

      In Professor Bradley Olsen’s lab in the Department of Chemical Engineering, Katharina Fransen works to develop biologically-based, biodegradable plastics which can be used for food packing that won’t pollute the environment. Fransen, a third-year PhD student, is motivated by the challenge of protecting the most vulnerable global communities from waste generated by the materials that are essential to connecting them to the global food supply. “We can’t ensure that all of our plastic waste gets recycled or reused, and so we want to make sure that if it does escape into the environment it can degrade, and that’s kind of where a lot of my research really comes in,” says Fransen. Most of her work involves creating polymers, or “really long chains of chemicals,” kind of like the paper rings a lot of us looped into chains as kids, Fransen explains. The polymers are optimized for food packaging applications to keep food fresher for longer, preventing food waste. Fransen says she finds the work “really interesting from the scientific perspective as well as from the idea that [she’s] going to make the world a little better with these new materials.” She adds, “I think it is both really fulfilling and really exciting and engaging.”

      Play video

      Aditya Ghodgaonkar

      “When I went to Kenya this past spring break, I had an opportunity to meet a lot of farmers and talk to them about what kind of maintenance issues they face,” says Aditya Ghodgaonkar, PhD candidate in the Department of Mechanical Engineering. Ghodgaonkar works with Associate Professor Amos Winter in the Global Engineering and Research (GEAR) Lab, where he designs hydraulic components for drip irrigation systems to make them water-efficient, off-grid, inexpensive, and low-maintenance. On his trip to Kenya, Ghodgaonkar gained firsthand knowledge from farmers about a common problem they encounter: clogging of drip irrigation emitters. He learned that clogging can be an expensive technical challenge to diagnose, mitigate, and resolve. He decided to focus his attention on designing emitters that are resistant to clogging, testing with sand and passive hydrodynamic filtration back in the lab at MIT. “I got into this from an academic standpoint,” says Ghodgaonkar. “It is only once I started working on the emitters, spoke with industrial partners that make these emitters, spoke with farmers, that I really truly appreciated the impact of what we’re doing.”

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      Devashish Gokhale

      Devashish Gokhale is a PhD student advised by Professor Patrick Doyle in the Department of Chemical Engineering. Gokhale’s commitment to global water security stems from his childhood in Pune, India, where both flooding and drought can occur depending on the time of year. “I’ve had these experiences where there’s been too much water and also too little water” he recalls. At MIT, Gokhale is developing cost-effective, sustainable, and reusable materials for water treatment with a focus on the elimination of emerging contaminants and low-concentration pollutants like heavy metals. Specifically, he works on making and optimizing polymeric hydrogel microparticles that can absorb micropollutants. “I know how important it is to do something which is not just scientifically interesting, but something which is impactful in a real way,” says Gokhale. Before starting a research project he asks himself, “are people going to be able to afford this? Is it really going to reach the people who need it the most?” Adding these constraints in the beginning of the research process sometimes makes the problem more difficult to solve, but Gokhale notes that in the end, the solution is much more promising.

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      James Zhang

      “We don’t really think much about it, it’s transparent, odorless, we just turn on our sink in many parts of the world and it just flows through,” says James Zhang when talking about water. Yet he notes that “many other parts of the world face water scarcity and this will only get worse due to global climate change.” A PhD student in the Department of Mechanical Engineering, Zhang works in the Nano Engineering Laboratory with Professor Gang Chen. Zhang is working on a technology that uses light-induced evaporation to clean water. He is currently investigating the fundamental properties of how light at different wavelengths interacts with liquids at the surface, particularly with brackish water surfaces. With strong theoretical and experimental components, his research could lead to innovations in desalinating water at high energy efficiencies. Zhang hopes that the technology can one day “produce lots of clean water for communities around the world that currently don’t have access to fresh water,” and create a new appreciation for this common liquid that many of us might not think about on a day-to-day basis.

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      Linzixuan (Rhoda) Zhang

      “Around the world there are about 2 billion people currently suffering from micronutrient deficiency because they do not have access to very healthy, very fresh food,” says chemical engineering PhD candidate Linzixuan (Rhoda) Zhang. This fact led Zhang to develop a micronutrient delivery platform that fortifies foods with essential vitamins and nutrients. With her advisors, Professor Robert Langer and Research Scientist Ana Jaklenec, Zhang brings biomedical engineering approaches to global health issues. Zhang says that “one of the most serious problems is vitamin A deficiency, because vitamin A is not very stable.” She goes on to explain that although vitamin A is present in different vegetables, when the vegetables are cooked, vitamin A can easily degrade. Zhang helped develop a group of biodegradable polymers that can stabilize micronutrients under cooking and storage conditions. With this technology, vitamin A, for example, could be encapsulated and effectively stabilized under boiling water. The platform has also shown efficient release in a simulation of the stomach environment. Zhang says it is the “little, tiny steps every day that are pushing us forward to the final impactful product.” More

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      in Security

      Pesticide innovation takes top prize at Collegiate Inventors Competition

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      On Oct. 12, MIT mechanical engineering alumnus Vishnu Jayaprakash SM ’19, PhD ’22 was named the first-place winner in the graduate category of the Collegiate Inventors Competition. The annual competition, which is organized by the National Inventors Hall of Fame, celebrates college and university student inventors. Jayaprakash won for his pesticide innovation AgZen-Cloak, which he developed while he was a student in the lab of Kripa Varanasi, a professor of mechanical engineering.

      Currently, only 2 percent of pesticide spray is retained by crops. Many crops are naturally water-repellent, causing pesticide-laden water to bounce off of them. Farmers are forced to over-spray significantly to ensure proper spray coverage on their crops. Not only does this waste expensive pesticides, but it also comes at an environmental cost.

      Runoff from pesticide treatment pollutes soil and nearby streams. Droplets can travel in the air, leading to illness and death in nearby populations. It is estimated that each year, pesticide pollution causes between 20,000 and 200,000 deaths, and up to 385 million acute illnesses like cancer, birth defects, and neurological conditions.   

      With his invention AgZen-Cloak, Jayaprakash has found a way to keep droplets of water containing pesticide from bouncing off crops by “cloaking” the droplets in a small amount of plant-derived oil. As a result, farmers could use just one-fifth the amount of spray, minimizing water waste and cost for farmers and eliminating airborne pollution and toxic runoff. It also improves pesticide retention, which can lead to higher crop yield.

      “By cloaking each droplet with a minute quantity of a plant-based oil, we promote water retention on even the most water-repellent plant surfaces,” says Jayaprakash. “AgZen-Cloak presents a universal, inexpensive, and environmentally sustainable way to prevent pesticide overuse and waste.”

      Farming is in Jayaprakash’s DNA. His family operates a 10-acre farm near Chennai, India, where they grow rice and mangoes. Upon joining the Varanasi Research Group as a graduate student, Jayaprakash was instantly drawn to Varanasi’s work on pesticides in agriculture.

      “Growing up, I would spray crops on my family farm wearing a backpack sprayer. So, I’ve always wanted to work on research that made farmer’s lives easier,” says Jayaprakash, who serves as CEO of the startup AgZen.

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      2022 World Food Day First Prize Winner – AgZen Cloak: Reducing Pesticide Pollution and Waste

      Helping droplets stick

      Varanasi and his lab at MIT work on what is known as interfacial phenomena — or the study of what happens when different phases come into contact and interact with one another. Understanding how a liquid interacts with a solid or how a liquid reacts to a certain gas has endless applications, which explains the diversity of the research Varanasi has conducted over the years. He and his team have developed solutions for everything from consumer product packaging to power plant emissions.

      In 2009, Varanasi gave a talk at the U.S. Department of Agriculture (USDA). There, he learned from the USDA just how big of a problem runoff from pesticide spray was for farmers around the world.
      A green cabbage leaf is treated with pesticide-laden water using conventional spraying. Image courtesy of AgZen.A green cabbage leaf is treated with pesticide-laden water using AgZen’s technology. By cloaking droplets in a tiny amount of plant-derived oil, the droplets stick to the leaf, minimizing over-spraying, waste, and pollution. Image courtesy of AgZen.He enlisted the help of then-graduate student Maher Damak SM ’15, PhD ’18 to apply their work in interfacial phenomena to pesticide sprays. Over the next several years, the Varanasi Research Group developed a technology that utilized electrically charged polymers to keep droplets from bouncing off hydrophobic surfaces. When droplets containing positively and negatively charged additives meet, their surface chemistry allows them to stick to a plant’s surface.

      Using polyelectrolytes, the researchers could reduce the amount of spray needed to cover a crop by tenfold in the lab. This motivated the Varanasi Research Group to pursue three years of field trials with various commercial growers around the world, where they were able to demonstrate significant savings for farmers.

      “We got fantastic feedback on our technology from farmers. We are really excited to change the paradigm for agriculture. Not only is it good for the environment, but we’ve heard from farmers that they love it. If we can put money back into farms, it helps society as a whole,” adds Varanasi.

      In response to the positive feedback, Varanasi and Jayaprakash co-founded startup AgZen in 2020. 

      When field testing their polyelectrolyte technology, Varanasi and Jayaprakash came up with the idea to explore the use of a fully plant-based material to help farmers achieve the same savings. 

      Cloaking droplets and engineering nozzles

      Jayaprakash found that by cloaking a small amount of plant-derived oil around a water droplet, droplets stick to plant surfaces that would typically repel water. After conducting many studies in the lab, he found that the oil only needs to make up 0.1 percent of a droplet’s total volume to stick to crops and provide total, uniform coverage.

      While his cloaking solution worked in the lab, Jayaprakash knew that to have a tangible impact in the real world he needed to find an easy, low-cost way for farmers to coat pesticide spray droplets in oil.

      Jayaprakash focused on spray nozzles. He developed a proprietary nozzle that coats each droplet with a small amount of oil as they are being formed. The nozzles can easily be added to any hose or farming equipment.

      “What we’ve done is figured out a smart way to cloak these droplets by using a very small quantity of oil on the outside of each drop. Because of that, we get this drastic improvement in performance that can really be a game-changer for farmers,” says Jayaprakash.

      In addition to improving pesticide retention in crops, the AgZen-Cloak solves a second problem. Since large droplets are prone to break apart and bounce off crops, historically, farmers have sprayed pesticide in tiny, mist-like droplets. These fine droplets are often carried by the wind, increasing pesticide pollution in nearby areas. 

      When AgZen-Cloak is used, the pesticide-laden droplets can be larger and still stick to crops. These larger droplets aren’t carried by the wind, decreasing the risk of pollution and minimizing the health impacts on local populations.  

      “We’re actually solving two problems with one solution. With the cloaking technology, we can spray much larger droplets that aren’t prone to wind drift and they can stick to the plant,” Jayaprakash adds.

      Bringing AgZen-Cloaks to farmers around the world

      This spring, Varanasi encouraged Jayaprakash to submit AgZen-Cloak to the Collegiate Inventors Competition. Out of hundreds of applications, Jayaprakash was one of 25 student inventors to be chosen as a finalist.

      On Oct. 12, Jayaprakash presented his technology to a panel of judges composed of National Inventors Hall of Fame inductees and U.S. Patent and Trademark Office officials. Meeting with such an illustrious group of inventors and officials left an impression on Jayaprakash.

      “These are people who have invented things that have changed the world. So, to get their feedback on what we’re doing was incredibly valuable,” he says. Jayaprakash received a $10,000 prize for being named the first-place graduate winner.

      As full-time CEO of AgZen, Jayaprakash is shifting focus to field testing and commercialization. He and the AgZen team have already conducted field testing across the world at locations including a Prosecco vineyard outside of Venice, a ranch in California, and Ward’s Berry Farm in Sharon, Massachusetts. The University of Massachusetts at Amherst’s vegetable extension program, led by their program director Susan Scheufele, recently concluded a field test that validated AgZen’s on-field performance.

      Two days after his win at the Collegiate Inventors Competition, Jayaprakash was named the first prize winner of the MIT Abdul Latif Jamel Water and Food Systems Lab World Food Day student video competition. Hours later, he flew across the country to attend an agricultural tech conference in California, eager to meet with farmers and discuss plans for rolling out AgZen’s innovations to farms everywhere. More

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      in Environment

      Coordinating climate and air-quality policies to improve public health

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      As America’s largest investment to fight climate change, the Inflation Reduction Act positions the country to reduce its greenhouse gas emissions by an estimated 40 percent below 2005 levels by 2030. But as it edges the United States closer to achieving its international climate commitment, the legislation is also expected to yield significant — and more immediate — improvements in the nation’s health. If successful in accelerating the transition from fossil fuels to clean energy alternatives, the IRA will sharply reduce atmospheric concentrations of fine particulates known to exacerbate respiratory and cardiovascular disease and cause premature deaths, along with other air pollutants that degrade human health. One recent study shows that eliminating air pollution from fossil fuels in the contiguous United States would prevent more than 50,000 premature deaths and avoid more than $600 billion in health costs each year.

      While national climate policies such as those advanced by the IRA can simultaneously help mitigate climate change and improve air quality, their results may vary widely when it comes to improving public health. That’s because the potential health benefits associated with air quality improvements are much greater in some regions and economic sectors than in others. Those benefits can be maximized, however, through a prudent combination of climate and air-quality policies.

      Several past studies have evaluated the likely health impacts of various policy combinations, but their usefulness has been limited due to a reliance on a small set of standard policy scenarios. More versatile tools are needed to model a wide range of climate and air-quality policy combinations and assess their collective effects on air quality and human health. Now researchers at the MIT Joint Program on the Science and Policy of Global Change and MIT Institute for Data, Systems and Society (IDSS) have developed a publicly available, flexible scenario tool that does just that.

      In a study published in the journal Geoscientific Model Development, the MIT team introduces its Tool for Air Pollution Scenarios (TAPS), which can be used to estimate the likely air-quality and health outcomes of a wide range of climate and air-quality policies at the regional, sectoral, and fuel-based level. 

      “This tool can help integrate the siloed sustainability issues of air pollution and climate action,” says the study’s lead author William Atkinson, who recently served as a Biogen Graduate Fellow and research assistant at the IDSS Technology and Policy Program’s (TPP) Research to Policy Engagement Initiative. “Climate action does not guarantee a clean air future, and vice versa — but the issues have similar sources that imply shared solutions if done right.”

      The study’s initial application of TAPS shows that with current air-quality policies and near-term Paris Agreement climate pledges alone, short-term pollution reductions give way to long-term increases — given the expected growth of emissions-intensive industrial and agricultural processes in developing regions. More ambitious climate and air-quality policies could be complementary, each reducing different pollutants substantially to give tremendous near- and long-term health benefits worldwide.

      “The significance of this work is that we can more confidently identify the long-term emission reduction strategies that also support air quality improvements,” says MIT Joint Program Deputy Director C. Adam Schlosser, a co-author of the study. “This is a win-win for setting climate targets that are also healthy targets.”

      TAPS projects air quality and health outcomes based on three integrated components: a recent global inventory of detailed emissions resulting from human activities (e.g., fossil fuel combustion, land-use change, industrial processes); multiple scenarios of emissions-generating human activities between now and the year 2100, produced by the MIT Economic Projection and Policy Analysis model; and emissions intensity (emissions per unit of activity) scenarios based on recent data from the Greenhouse Gas and Air Pollution Interactions and Synergies model.

      “We see the climate crisis as a health crisis, and believe that evidence-based approaches are key to making the most of this historic investment in the future, particularly for vulnerable communities,” says Johanna Jobin, global head of corporate reputation and responsibility at Biogen. “The scientific community has spoken with unanimity and alarm that not all climate-related actions deliver equal health benefits. We’re proud of our collaboration with the MIT Joint Program to develop this tool that can be used to bridge research-to-policy gaps, support policy decisions to promote health among vulnerable communities, and train the next generation of scientists and leaders for far-reaching impact.”

      The tool can inform decision-makers about a wide range of climate and air-quality policies. Policy scenarios can be applied to specific regions, sectors, or fuels to investigate policy combinations at a more granular level, or to target short-term actions with high-impact benefits.

      TAPS could be further developed to account for additional emissions sources and trends.

      “Our new tool could be used to examine a large range of both climate and air quality scenarios. As the framework is expanded, we can add detail for specific regions, as well as additional pollutants such as air toxics,” says study supervising co-author Noelle Selin, professor at IDSS and the MIT Department of Earth, Atmospheric and Planetary Sciences, and director of TPP.    

      This research was supported by the U.S. Environmental Protection Agency and its Science to Achieve Results (STAR) program; Biogen; TPP’s Leading Technology and Policy Initiative; and TPP’s Research to Policy Engagement Initiative. More