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      in Energy

      MIT engineers design tiny batteries for powering cell-sized robots

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      A tiny battery designed by MIT engineers could enable the deployment of cell-sized, autonomous robots for drug delivery within in the human body, as well as other applications such as locating leaks in gas pipelines.The new battery, which is 0.1 millimeters long and 0.002 millimeters thick — roughly the thickness of a human hair — can capture oxygen from air and use it to oxidize zinc, creating a current of up to 1 volt. That is enough to power a small circuit, sensor, or actuator, the researchers showed.“We think this is going to be very enabling for robotics,” says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT and the senior author of the study. “We’re building robotic functions onto the battery and starting to put these components together into devices.”Ge Zhang PhD ’22 and Sungyun Yang, an MIT graduate student, are the lead author of the paper, which appears in Science Robotics.Powered by batteriesFor several years, Strano’s lab has been working on tiny robots that can sense and respond to stimuli in their environment. One of the major challenges in developing such tiny robots is making sure that they have enough power.Other researchers have shown that they can power microscale devices using solar power, but the limitation to that approach is that the robots must have a laser or another light source pointed at them at all times. Such devices are known as “marionettes” because they are controlled by an external power source. Putting a power source such as a battery inside these tiny devices could free them to roam much farther.“The marionette systems don’t really need a battery because they’re getting all the energy they need from outside,” Strano says. “But if you want a small robot to be able to get into spaces that you couldn’t access otherwise, it needs to have a greater level of autonomy. A battery is essential for something that’s not going to be tethered to the outside world.”To create robots that could become more autonomous, Strano’s lab decided to use a type of battery known as a zinc-air battery. These batteries, which have a longer lifespan than many other types of batteries due to their high energy density, are often used in hearing aids.The battery that they designed consists of a zinc electrode connected to a platinum electrode, embedded into a strip of a polymer called SU-8, which is commonly used for microelectronics. When these electrodes interact with oxygen molecules from the air, the zinc becomes oxidized and releases electrons that flow to the platinum electrode, creating a current.In this study, the researchers showed that this battery could provide enough energy to power an actuator — in this case, a robotic arm that can be raised and lowered. The battery could also power a memristor, an electrical component that can store memories of events by changing its electrical resistance, and a clock circuit, which allows robotic devices to keep track of time.The battery also provides enough power to run two different types of sensors that change their electrical resistance when they encounter chemicals in the environment. One of the sensors is made from atomically thin molybdenum disulfide and the other from carbon nanotubes.“We’re making the basic building blocks in order to build up functions at the cellular level,” Strano says.Robotic swarmsIn this study, the researchers used a wire to connect their battery to an external device, but in future work they plan to build robots in which the battery is incorporated into a device.“This is going to form the core of a lot of our robotic efforts,” Strano says. “You can build a robot around an energy source, sort of like you can build an electric car around the battery.”One of those efforts revolves around designing tiny robots that could be injected into the human body, where they could seek out a target site and then release a drug such as insulin. For use in the human body, the researchers envision that the devices would be made of biocompatible materials that would break apart once they were no longer needed.The researchers are also working on increasing the voltage of the battery, which may enable additional applications.The research was funded by the U.S. Army Research Office, the U.S. Department of Energy, the National Science Foundation, and a MathWorks Engineering Fellowship. More

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      in Energy

      D-Lab off-grid brooder saves chicks and money using locally manufactured thermal batteries

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      MIT D-Lab students and instructors are improving the efficacy and economics of a brooder technology for newborn chicks that utilizes a practical, local resource: beeswax.Developed through participatory design with agricultural partners in Cameroon, their Off-Grid Brooder is a solution aimed at improving the profitability of the African nation’s small- and medium-scale poultry farms. Since it is common for smallholders in places with poor electricity supply to tend open fires overnight to keep chicks warm, the invention might also let farmers catch up on their sleep.“The target is eight hours. If farmers can sustain the warmth for eight hours, then they get to sleep,” says D-Lab instructor and former student Ahmad (Zak) Zakka SM ’23, who traveled to Cameroon in May to work on implementing brooder improvements tested at the D-Lab, along with D-Lab students, collaborators from African Solar Generation (ASG), and the African Diaspora Council of Switzerland – Branch Cameroon (CDAS–BC).Poultry farming is heavily concentrated in lower- and middle-income countries, where it is an important component of rural economies and provides an inexpensive source of protein for residents. Raising chickens is fraught with economic risk, however, largely because it is hard for small-scale farmers to keep newborn chicks warm enough to survive (33 to 35 degrees Celsius, or 91 to 95 degrees Fahrenheit, depending on age). After the cost of feed, firewood used to heat the chick space is the biggest input for rural poultry farmers.According to D-Lab researchers, an average smallholder in Cameroon using traditional brooding methods spends $17 per month on firewood, achieves a 10 percent profit margin, and experiences chick mortality that can be as high as a total loss due to overheating or insufficient heat. The Off-Grid Brooder is designed to replace open fires with inexpensive, renewable, and locally available beeswax — a phase-change material used to make thermal batteries.ASG initially developed a brooder technology, the SolarBox, that used photovoltaic panels and electric batteries to power incandescent bulbs. While this provided effective heating, it was prohibitively expensive and difficult to maintain. In 2020, students from the D-Lab Energy class took on the challenge of reducing the cost and complexity of the SolarBox heating system to make it more accessible to small farmers in Cameroon. Through participatory design — a collaborative approach that involves all stakeholders in early stages of the design process — the team discovered a unique solution. Beeswax stored in a used glass container (such as a mayonnaise jar) is melted using a double boiler over a fire and then installed inside insulated brooder boxes alongside the chicks. As the beeswax cools and solidifies, it releases heat for several hours, keeping the brooder within the temperature range that chicks need to grow and develop. Farmers can then recharge the cooled wax batteries and repeat the process again and again. “The big challenge was how to get heat,” says D-Lab Research Scientist Daniel Sweeney, who, with Zakka, co-teaches two D-Lab classes, 2.651/EC.711 (Introduction to Energy in Global Development), and 2.652/EC.712 (Applications of Energy in Global Development). “Decoupling the heat supplied by biomass (wood) from the heat the chicks need at night in the brooder, that’s the core of the innovation here.”D-Lab instructors, researchers, and students have tested and tuned the system with partners in Cameroon. A research box constructed during a D-Lab trip to Cameroon in January 2023 worked well, but was “very expensive to build,” Zakka says. “The research box was a proof of concept in the field. The next step was to figure out how to make it affordable,” he continues.A new brooder box, made entirely of locally sourced recycled materials at 5 percent of the cost of the research prototype, was developed during D-Lab’s January 2024 trip to Cameroon. Designed and produced in collaboration with CDAS-BC, the new brooder is much more affordable, but its functionality still needs fine-tuning. From late-May through mid-June, the D-Lab team, led by Zakka, worked with Cameroonian collaborators to improve the system again. This time, they assessed the efficacy of using straw, a readily available and low-cost material, arranged in panels to insulate the brooder box.The MIT team was hosted by CDAS-BC, including its president and founder Carole Erlemann Mengue and secretary and treasurer Kathrin Witschi, who operate an organic poultry farm in Afambassi, Cameroon. “The students will experiment with the box and try to improve the insulation of the box without neglecting that the chicks will need ventilation,” they say.In addition, the CDAS-BC partners say that they hoped to explore increasing the number of chicks that the box can keep warm. “If the system could heat 500 to 1,000 chicks at a time,” they note, “it would help farmers save firewood, to sleep through the night, and to minimize the risk of fire in the building and the risk of stepping on chicks while replacing firewood.” Earlier this spring, Erlemann Mengue and Witschi tested the low-cost Off-Grid Brooder Box, which can hold 30 to 40 chicks in its current design.“They were very interested in partnering with us to evaluate the technology. They are running the tests and doing a lot of technical measurement to track the temperature inside the brooder over time,” says Sweeney, adding that the CDAS-BC partners are amassing datasets that they send to the MIT D-Lab team. Sweeney and Zakka, along with PhD candidate Aly Kombargi, who worked on the research box in Cameroon last year, hope to not only improve the functionality of the Off-Grid Poultry Brooder but also broaden its use beyond Cameroon.“The goal of our trip was to have a working prototype, and the goal since then has been to scale this up,” Kombargi says. “It’s absolutely scalable.”Concurring that “the technology should work across developing countries in small-scale poultry sectors,” Zakka says this spring’s D-Lab trip included workshops for area poultry farmers to teach them about benefits of the Off-Grid Brooder and how to make their own. “I’m excited to see if we can get people excited about pushing this as a business … to see if they would build and sell it to other people in the community,” Zakka says.Adds Sweeney, “This isn’t rocket science. If we have some guidance and some open-source information we could share, I’m pretty sure (farmers) could put them together on their own.”Already, he says, partners identified through MIT’s networks in Zambia and Uganda are building their own brooders based on the D-Lab design.MIT’s Abdul Latif Jameel Water and Food Systems Lab (J-WAFS), which supports research, innovation, and cross-disciplinary collaborations involving water and food systems, awarded the Off-Grid Brooder project a $25,000 research and development grant in 2022. The program is “pleased that the project’s approach was grounded in engagement with MIT students and community collaborators,” says Executive Director Renee Robins. “The participatory design process helped produce innovative prototypes that are already making positive impacts for smallholder poultry farmers.”That process and the very real impact on communities in Cameroon is what draws students to the project and keeps them committed.Sweeney says a recent D-Lab design review for the chick brooder highlighted that the project continued to attract the attention and curiosity of students who participated in earlier stages and still want to be involved.“There’s something about this project. There’s this whole tribe of students that are still active on the broader project,” he says. “There’s something about it.” More

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      in Environment

      Q&A: “As long as you have a future, you can still change it”

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      Tristan Brown is the S.C. Fang Chinese Language and Culture Career Development Professor at MIT. He specializes in law, science, environment and religion of late imperial China, a period running from the 16th through early 20th centuries.In this Q&A, Brown discusses how his areas of historical research can be useful for examining today’s pressing environmental challenges. This is part of an ongoing series exploring how the MIT School of Humanities, Arts, and Social Sciences is addressing the climate crisis.Q: Why does this era of Chinese history resonate so much for you? How is it relevant to contemporary times and challenges?A: China has always been interesting to historians because it has a long-recorded history, with data showing how people have coped with environmental and climate changes over the centuries. We have tons of records of various kinds of ecological issues, environmental crises, and the associated outbreaks of calamities, famine, epidemics, and warfare. Historians of China have a lot to offer ongoing conversations about climate.More specifically, I research conflicts over land and resources that erupted when China was undergoing huge environmental, economic, demographic, and political pressures, and the role that feng shui played as local communities and the state tried to mediate those conflicts. [Feng shui is an ancient Chinese practice combining cosmology, spatial aesthetics, and measurement to divine the right balance between the natural and built environment.] Ultimately, the Qing (1644-1912) state was unable to manage these conflicts, and feng shui–based attempts to make decisions about conserving or exploiting certain areas blew up by the end of the 19th century in the face of pressures to industrialize. This is the subject of my first book, “Laws of the Land: Fengshui and the State in Qing Dynasty China.”Q: Can you give a sense of how feng shui was used to determine outcomes in environmental cases?A: We tend to think of feng shui as a popular design mechanism today. While this isn’t completely inaccurate, there was much more to it than that in Chinese history, when it evolved over many centuries. Specifically, there are lots of insights in feng shui that reflect the ways in which people recorded the natural world, explained how components in the environment related to one another, and understood why and how bad things happened. There is an interesting concept in feng shui that your environment affects your health,and specifically your children’s (i.e., descendants and progeny) health. That concept is found across premodern feng shui literature and is one of fundamental principles of the whole knowledge system.During the period I research, the Qing, the primary fuel energy sources in China came from timber and coal. There were legal cases where communities argued against efforts to mine a local mountain, saying that it could injure the feng shui (i.e., undermine the cosmological balance of natural forces and spatial integrity) of a mountain and hurt the fortunes of an entire region. People were suspicious of coal mining in their communities. They had seen or heard about mines collapsing and flooded mine shafts, they had watched runoff ruin good farmland, causing crops to fail, and even perhaps children to fall ill. Coal mining disturbed the human-earth connection, and thus the relationship between people and nature. People invoked feng shui to express an idea that the extraction of rocks and minerals from the land can have detrimental effects on living communities. Whether out of a sincere community-based concern or out of a more self-interested NIMBYism, feng shui was the primary discourse invoked in these cases.Not all efforts to conserve areas from mining succeeded, especially as foreign imperialism encroached on China, threatening government and local control over the economy. It became gradually clear to China’s elites that the country had to industrialize to survive, and this involved the difficult and even violent process of taking people from farm work and bringing them to cities, building railways, cutting millions of trees, and mining coal to power it all.Q: This makes it seem as if the Chinese swept away feng shui whenever it presented a hurdle, putting the country on the path to coal dependence, pollution, and a carbon-emitting future.A: Feng shui has not disappeared in China, but there’s no doubt about it that development in the form of industrialization took precedence in the 20th century, when it became officially labelled a “superstition” on the national stage. When I first went to China in 2007, city air was so polluted I couldn’t see the horizon. I was 18 years old and the air in some northern cities like Shijiazhuang honestly felt scary. I’ve returned many times since then, of course, and there has been great improvement in air quality, because the government made it a priority.Feng shui is a future-oriented knowledge, concerned with identifying events that have happened in the past that are related to things happening today, and using that information to influence future events. As Richard Smith of Rice University argues, Chinese have used history to order the past, ritual to order the present, and divination to order the future. Consider, for instance, Xiong’an, a new development area outside of Beijing that is physically marking the era of Xi Jinping’s tenure as paramount leader. As soon as the site was selected, people in China started talking about its feng shui, both out of potential environmental concerns and as a subtle form of political commentary. MIT’s own Sol Andrew Stokols in the Department of Urban Studies and Planning (DUSP) has a fantastic new dissertation examining that new area.In short, the feng shui masters of old said there will be floods and droughts and bad stuff happening in the future if a course correction isn’t made. But at the same time, in feng shui there’s never a situation that is hopeless; there is no lost cause. So, there is optimism in the knowledge and rhetoric of feng shui that I think might be applicable as time goes on with climate change. As long as you have a future, you can still change it. Q: In 2023, you were awarded one of the first grants of MIT’s Climate Nucleus, the faculty committee charged with seeing through the Institute’s climate action plan over the decade. What have you been up to courtesy of this fund?A: Well, it all started years ago, when I started thinking about great number of mountains in China associated with Buddhism or Daoism that have become national parks in recent decades. Some of these mountains host trees and plant species that are not found in any other part of China. For my grant, I wanted to find out how these mountains have managed to incubate such rare species for the last 2,000 years. And it’s not as simple as just saying, well, Buddhism, right? Because there are plenty of Buddhist mountains that have not fared as well ecologically. The religious landscape is part of the answer, but there’s also all the messiness of material history that surrounds such a mountain.With this grant, I am bringing together a group of scholars of religion, historians, as well as engineers working in conservation ecology, and we’re trying to figure out what makes some of these places religiously and environmentally distinctive. People come to the project with different approaches. My MIT colleague Serguei Saavedra in the Department of Civil and Environmental Engineering uses new models in system ecology to measure the resilience of environments under various stresses. My colleague in religious studies, Or Porath at Tel Aviv University, is asking when and how Asian religions have centered — or ignored — animals and animal welfare. Another collaboration with MIT’s Siqi Zheng in DUSP and Wen-Chi Liao at the National University of Singapore is looking at how we can use artificial intelligence, machine learning, and classical feng shui manuals to teach computers how to analyze the value of a property’s feng shui in Sinophone communities around the world. There’s a lot going on!Q: How do you bring China’s unique environmental history and law into your classroom, and make it immediate and relevant to the world students face today?A: History is always part of the answer. I mean, whether it’s for an economist, a political scientist, or an architect, history matters. Likewise, when you’re confronting climate change and all these struggles regarding the environment and various crises involving ecosystems, it’s always a good idea to look at how human beings in the past dealt with similar crises. It doesn’t give you a prediction on what would happen in the future, but it gives you some range of possibilities, many of which may at first appear counterintuitive or surprising.That’s exactly what the humanities do. My job is to make MIT undergraduates care about a people who are no longer alive, who walked the earth a thousand years ago, who confronted terrible times of conflict and hunger. Sometimes these people left behind a written record about their world, and sometimes they didn’t. But we try to hear them out regardless. I want students to develop empathy for these strangers and wonder what it would be like to walk in their shoes. Every one of those people is someone’s ancestor, and they very well could have been your ancestor.In my class 21H.186 (Nature and Environment in China), we look at the historical precedents that might be useful for today’s environmental challenges, ranging from urban pollution or domestic recycling systems. The fact we’re still here to ask historical questions is itself significant. When we feel despair about climate change, we can ask, “How did individuals endure the changed course of the Yellow River or the Little Ice Age?” Even when it is recording tragedies, history can be understood as an enduring form of hope.  More

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      in Environment

      Mission directors announced for the Climate Project at MIT

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      The Climate Project at MIT has appointed leaders for each of its six focal areas, or Climate Missions, President Sally Kornbluth announced in a letter to the MIT community today.Introduced in February, the Climate Project at MIT is a major new effort to change the trajectory of global climate outcomes for the better over the next decade. The project will focus MIT’s strengths on six broad climate-related areas where progress is urgently needed. The mission directors in these fields, representing diverse areas of expertise, will collaborate with faculty and researchers across MIT, as well as each other, to accelerate solutions that address climate change.“The mission directors will be absolutely central as the Climate Project seeks to marshal the Institute’s talent and resources to research, develop, deploy and scale up serious solutions to help change the planet’s climate trajectory,” Kornbluth wrote in her letter, adding: “To the faculty members taking on these pivotal roles: We could not be more grateful for your skill and commitment, or more enthusiastic about what you can help us all achieve, together.”The Climate Project will expand and accelerate MIT’s efforts to both reduce greenhouse gas emissions and respond to climate effects such as extreme heat, rising sea levels, and reduced crop yields. At the urgent pace needed, the project will help the Institute create new external collaborations and deepen existing ones to develop and scale climate solutions.The Institute has pledged an initial $75 million to the project, including $25 million from the MIT Sloan School of Management to launch a complementary effort, the new MIT Climate Policy Center. MIT has more than 300 faculty and senior researchers already working on climate issues, in collaboration with their students and staff. The Climate Project at MIT builds on their work and the Institute’s 2021 “Fast Forward” climate action plan.Richard Lester, MIT’s vice provost for international activities and the Japan Steel Industry Professor of Nuclear Science and Engineering, has led the Climate Project’s formation; MIT will shortly hire a vice president for climate to oversee the project. The six Climate Missions and the new mission directors are as follows:Decarbonizing energy and industryThis mission supports advances in the electric power grid as well as the transition across all industry — including transportation, computing, heavy production, and manufacturing — to low-emissions pathways.The mission director is Elsa Olivetti PhD ’07, who is MIT’s associate dean of engineering, the Jerry McAfee Professor in Engineering, and a professor of materials science and engineering since 2014.Olivetti analyzes and improves the environmental sustainability of materials throughout the life cycle and across the supply chain, by linking physical and chemical processes to systems impact. She researches materials design and synthesis using natural language processing, builds models of material supply and technology demand, and assesses the potential for recovering value from industrial waste through experimental approaches. Olivetti has experience building partnerships across the Institute and working with industry to implement large-scale climate solutions through her role as co-director of the MIT Climate and Sustainability Consortium (MCSC) and as faculty lead for PAIA, an industry consortium on the carbon footprinting of computing.Restoring the atmosphere, protecting the land and oceansThis mission is centered on removing or storing greenhouse gases that have already been emitted into the atmosphere, such as carbon dioxide and methane, and on protecting ocean and land ecosystems, including food and water systems.MIT has chosen two mission directors: Andrew Babbin and Jesse Kroll. The two bring together research expertise from two critical domains of the Earth system, oceans and the atmosphere, as well as backgrounds in both the science and engineering underlying our understanding of Earth’s climate. As co-directors, they jointly link MIT’s School of Science and School of Engineering in this domain.Babbin is the Cecil and Ida Green Career Development Professor in MIT’s Program in Atmospheres, Oceans, and Climate. He is a marine biogeochemist whose specialty is studying the carbon and nitrogen cycle of the oceans, work that is related to evaluating the ocean’s capacity for carbon storage, an essential element of this mission’s work. He has been at MIT since 2017.Kroll is a professor in MIT’s Department of of Civil and Environmental Engineering, a professor of chemical engineering, and the director of the Ralph M. Parsons Laboratory. He is a chemist who studies organic compounds and particulate matter in the atmosphere, in order to better understand how perturbations to the atmosphere, both intentional and unintentional, can affect air pollution and climate.Empowering frontline communitiesThis mission focuses on the development of new climate solutions in support of the world’s most vulnerable populations, in areas ranging from health effects to food security, emergency planning, and risk forecasting.The mission director is Miho Mazereeuw, an associate professor of architecture and urbanism in MIT’s Department of Architecture in the School of Architecture and Planning, and director of MIT’s Urban Risk Lab. Mazereeuw researches disaster resilience, climate change, and coastal strategies. Her lab has engaged in design projects ranging from physical objects to software, while exploring methods of engaging communities and governments in preparedness efforts, skills she brings to bear on building strong collaborations with a broad range of stakeholders.Mazereeuw is also co-lead of one of the five projects selected in MIT’s Climate Grand Challenges competition in 2022, an effort to help communities prepare by understanding the risk of extreme weather events for specific locations.Building and adapting healthy, resilient citiesA majority of the world’s population lives in cities, so urban design and planning is a crucial part of climate work, involving transportation, infrastructure, finance, government, and more.Christoph Reinhart, the Alan and Terri Spoon Professor of Architecture and Climate and director of MIT’s Building Technology Program in the School of Architecture and Planning, is the mission director in this area. The Sustainable Design Lab that Reinhart founded when he joined MIT in 2012 has launched several technology startups, including Mapdwell Solar System, now part of Palmetto Clean Technology, as well as Solemma, makers of an environmental building design software used in architectural practice and education worldwide. Reinhart’s online course on Sustainable Building Design has an enrollment of over 55,000 individuals and forms part of MIT’s XSeries Program in Future Energy Systems.Inventing new policy approachesClimate change is a unique crisis. With that in mind, this mission aims to develop new institutional structures and incentives — in carbon markets, finance, trade policy, and more — along with decision support tools and systems for scaling up climate efforts.Christopher Knittel brings extensive knowledge of these topics to the mission director role. The George P. Shultz Professor and Professor of Applied Economics at the MIT Sloan School of Management, Knittel has produced high-impact research in multiple areas; his studies on emissions and the automobile industry have evaluated fuel-efficiency standards, changes in vehicle fuel efficiency, market responses to fuel-price changes, and the health impact of automobiles.Beyond that, Knittel has also studied the impact of the energy transition on jobs, conducted high-level evaluations of climate policies, and examined energy market structures. He joined the MIT faculty in 2011. He also serves as the director of the MIT Climate Policy Center, which will work closely with all six missions.Wild cardsThis mission consists of what the Climate Project at MIT calls “unconventional solutions outside the scope of the other missions,” and will have a broad portfolio for innovation.While all the missions will be charged with encouraging unorthodox approaches within their domains, this mission will seek out unconventional solutions outside the scope of the others, and has a broad mandate for promoting them.The mission director in this case is Benedetto Marelli, the Paul M. Cook Career Development Associate Professor in MIT’s Department of Civil and Environmental Engineering. Marelli’s research group develops biopolymers and bioinspired materials with reduced environmental impact compared to traditional technologies. He engages with research at multiple scales, including nanofabrication, and the research group has conducted extensive work on food security and safety while exploring new techniques to reduce waste through enhanced food preservation and to precisely deliver agrochemicals in plants and in soil.As Lester and other MIT leaders have noted, the Climate Project at MIT is still being shaped, and will have the flexibility to accommodate a wide range of projects, partnerships, and approaches needed for thoughtful, fast-moving change. By filling out the leadership structure, today’s announcement is a major milestone in making the project operational.In addition to the six Climate Missions, the Climate Project at MIT includes Climate Frontier Projects, which are efforts launched by these missions, and a Climate HQ, which will support fundamental research, education, and outreach, as well as new resources to connect research to the practical work of climate response. More

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      in Energy

      Proton-conducting materials could enable new green energy technologies

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      As the name suggests, most electronic devices today work through the movement of electrons. But materials that can efficiently conduct protons — the nucleus of the hydrogen atom — could be key to a number of important technologies for combating global climate change.Most proton-conducting inorganic materials available now require undesirably high temperatures to achieve sufficiently high conductivity. However, lower-temperature alternatives could enable a variety of technologies, such as more efficient and durable fuel cells to produce clean electricity from hydrogen, electrolyzers to make clean fuels such as hydrogen for transportation, solid-state proton batteries, and even new kinds of computing devices based on iono-electronic effects.In order to advance the development of proton conductors, MIT engineers have identified certain traits of materials that give rise to fast proton conduction. Using those traits quantitatively, the team identified a half-dozen new candidates that show promise as fast proton conductors. Simulations suggest these candidates will perform far better than existing materials, although they still need to be conformed experimentally. In addition to uncovering potential new materials, the research also provides a deeper understanding at the atomic level of how such materials work.The new findings are described in the journal Energy and Environmental Sciences, in a paper by MIT professors Bilge Yildiz and Ju Li, postdocs Pjotrs Zguns and Konstantin Klyukin, and their collaborator Sossina Haile and her students from Northwestern University. Yildiz is the Breene M. Kerr Professor in the departments of Nuclear Science and Engineering, and Materials Science and Engineering.“Proton conductors are needed in clean energy conversion applications such as fuel cells, where we use hydrogen to produce carbon dioxide-free electricity,” Yildiz explains. “We want to do this process efficiently, and therefore we need materials that can transport protons very fast through such devices.”Present methods of producing hydrogen, for example steam methane reforming, emit a great deal of carbon dioxide. “One way to eliminate that is to electrochemically produce hydrogen from water vapor, and that needs very good proton conductors,” Yildiz says. Production of other important industrial chemicals and potential fuels, such as ammonia, can also be carried out through efficient electrochemical systems that require good proton conductors.But most inorganic materials that conduct protons can only operate at temperatures of 200 to 600 degrees Celsius (roughly 450 to 1,100 Fahrenheit), or even higher. Such temperatures require energy to maintain and can cause degradation of materials. “Going to higher temperatures is not desirable because that makes the whole system more challenging, and the material durability becomes an issue,” Yildiz says. “There is no good inorganic proton conductor at room temperature.” Today, the only known room-temperature proton conductor is a polymeric material that is not practical for applications in computing devices because it can’t easily be scaled down to the nanometer regime, she says.To tackle the problem, the team first needed to develop a basic and quantitative understanding of exactly how proton conduction works, taking a class of inorganic proton conductors, called solid acids. “One has to first understand what governs proton conduction in these inorganic compounds,” she says. While looking at the materials’ atomic configurations, the researchers identified a pair of characteristics that directly relates to the materials’ proton-carrying potential.As Yildiz explains, proton conduction first involves a proton “hopping from a donor oxygen atom to an acceptor oxygen. And then the environment has to reorganize and take the accepted proton away, so that it can hop to another neighboring acceptor, enabling long-range proton diffusion.” This process happens in many inorganic solids, she says. Figuring out how that last part works — how the atomic lattice gets reorganized to take the accepted proton away from the original donor atom — was a key part of this research, she says.The researchers used computer simulations to study a class of materials called solid acids that become good proton conductors above 200 degrees Celsius. This class of materials has a substructure called the polyanion group sublattice, and these groups have to rotate and take the proton away from its original site so it can then transfer to other sites. The researchers were able to identify the phonons that contribute to the flexibility of this sublattice, which is essential for proton conduction. Then they used this information to comb through vast databases of theoretically and experimentally possible compounds, in search of better proton conducting materials.As a result, they found solid acid compounds that are promising proton conductors and that have been developed and produced for a variety of different applications but never before studied as proton conductors; these compounds turned out to have just the right characteristics of lattice flexibility. The team then carried out computer simulations of how the specific materials they identified in their initial screening would perform under relevant temperatures, to confirm their suitability as proton conductors for fuel cells or other uses. Sure enough, they found six promising materials, with predicted proton conduction speeds faster than the best existing solid acid proton conductors.“There are uncertainties in these simulations,” Yildiz cautions. “I don’t want to say exactly how much higher the conductivity will be, but these look very promising. Hopefully this motivates the experimental field to try to synthesize them in different forms and make use of these compounds as proton conductors.”Translating these theoretical findings into practical devices could take some years, she says. The likely first applications would be for electrochemical cells to produce fuels and chemical feedstocks such as hydrogen and ammonia, she says.The work was supported by the U.S. Department of Energy, the Wallenberg Foundation, and the U.S. National Science Foundation. More

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      in Environment

      Collaborative effort supports an MIT resilient to the impacts of extreme heat

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      Warmer weather can be a welcome change for many across the MIT community. But as climate impacts intensify, warm days are often becoming hot days with increased severity and frequency. Already this summer, heat waves in June and July brought daily highs of over 90 degrees Fahrenheit. According to the Resilient Cambridge report published in 2021, from the 1970s to 2000, data from the Boston Logan International Airport weather station reported an average of 10 days of 90-plus temperatures each year. Now, simulations are predicting that, in the current time frame of 2015-44, the number of days above 90 F could be triple the 1970-2000 average. While the increasing heat is all but certain, how institutions like MIT will be affected and how they respond continues to evolve. “We know what the science is showing, but how will this heat impact the ability of MIT to fulfill its mission and support its community?” asks Brian Goldberg, assistant director of the MIT Office of Sustainability. “What will be the real feel of these temperatures on campus?” These questions and more are guiding staff, researchers, faculty, and students working collaboratively to understand these impacts to MIT and inform decisions and action plans in response.This work is part of developing MIT’s forthcoming Climate Resiliency and Adaptation Roadmap, which is called for in MIT’s climate action plan, and is co-led by Goldberg; Laura Tenny, senior campus planner; and William Colehower, senior advisor to the vice president for campus services and stewardship. This effort is also supported by researchers in the departments of Urban Studies and Planning, Architecture, and Electrical Engineering and Computer Science (EECS), in the Urban Risk Lab and the Senseable City Lab, as well as by staff in MIT Emergency Management and Housing and Residential Services. The roadmap — which builds upon years of resiliency planning and research at MIT — will include an assessment of current and future conditions on campus as well as strategies and proposed interventions to support MIT’s community and campus in the face of increasing climate impacts.A key piece of the resiliency puzzleWhen the City of Cambridge released their Climate Change Vulnerability Assessment in 2015, the report identified flooding and heat as primary resiliency risks to the city. In response, Institute staff worked together with the city to create a full picture of potential flood risks to both Cambridge and the campus, with the latter becoming the MIT Climate Resiliency Dashboard. The dashboard, published in the MIT Sustainability DataPool, has played an important role in campus planning and resiliency efforts since its debut in 2021, but heat has been a missing piece of the tool. This is largely because for heat, unlike flooding, few data exist relative to building-level impacts. The original assessment from Cambridge showed a model of temperature averages that could be expected in portions of the city, but understanding the measured heat impacts down to the building level is essential because impacts of heat can vary so greatly. “Heat also doesn’t conform to topography like flooding, making it harder to map it with localized specificity,” notes Tenny. “Microclimates, humidity levels, shade or sun aspect, and other factors contribute to heat risk.”Collection efforts have been underway for the past three years to fill in this gap in baseline data. Members of the Climate and Resiliency Adaptation Roadmap team and partners have helped build and place heat sensors to record and analyze data. The current heat sensors, which are shoebox-shaped devices on tripods, can be found at multiple outdoor locations on campus during the summer, capturing and recording temperatures multiple times each hour. “Urban environmental phenomena are hyperlocal. While National Weather Service readouts at locations like Logan Airport are extremely valuable, this gives us a more high-resolution understanding of the urban microclimate on our campus,” notes Sanjana Paul, past technical associate with Senseable City and current graduate student in the Department of Urban Studies and Planning who helps oversee data collection and analysis.After collection, temperature data are analyzed and mapped. The data will soon be published in the updated Climate Resiliency Dashboard and will help inform actions through the Climate Resiliency and Adaptation Roadmap, but in the meantime, the information has already provided some important insights. “There were some parts of campus that were much hotter than I expected,” explains Paul. “Some of the temperature readings across campus were regularly going over 100 degrees during heat waves. It’s a bit surprising to see three digits on a temperature reading in Cambridge.” Some strategies are also already being put into action, including planting more trees to support the urban campus forest and launching cooling locations around campus to open during days of extreme heat.As data gathering enters its fourth summer, partners continue to expand. Senseable City first began capturing data in 2021 using sensors placed on MIT Recycling trucks, and the Urban Risk Lab has offered community-centered temperature data collection with the help of its director and associate professor of architecture, Miho Mazereeuw. More recently, students in course 6.900 (Engineering for Impact) worked to design heat sensors to aid in the data collection and grow the fleet of sensors on campus. Co-instructed by EECS senior lecturer Joe Steinmeyer and EECS professor Joel Voldman, students in the course were tasked with developing technology to solve challenges close at hand. “One of the goals of the class is to tackle real-world problems so students emerge with confidence as an engineer,” explains Voldman. “Having them work on a challenge that is outside their comfort zone and impacts them really helps to engage and inspire them.” Centering on peopleWhile the temperature data offer one piece of the resiliency planning puzzle, knowing how these temperatures will affect community members is another. “When we look at impacts to our campus from heat, people are the focus,” explains Goldberg. “While stress on campus infrastructure is one factor we are evaluating, our primary focus is the vulnerability of people to extreme heat.” Impacts to community members can range from disrupted nights of sleep to heat-related illnesses.As the team looked at the data and spoke with individuals across campus, it became clear that some community members might be more vulnerable than others to the impact of extreme heat days, including ground, janitorial, and maintenance crews who work outside; kitchen staff who work close to hot equipment; and student athletes exerting themselves on hot days. “We know that people on our campus are already experiencing these extreme heat days differently,” explains Susy Jones, senior sustainability project manager in the Office of Sustainability who focuses on environmental and climate justice. “We need to design strategies and augment existing interventions with equity in mind, ensuring everyone on campus can fulfill their role at MIT.”To support those strategy decisions, the resiliency team is seeking additional input from the MIT community. One hoped-for outcome of the roadmap and dashboard is for community members to review them and offer their own insight and experiences of heat conditions on campus. “These plans need to work at the campus level and the individual,” says Goldberg. “The data tells an important story, but individuals help us complete the picture.”A model for othersAs the dashboard update nears completion and the broader resiliency and adaptation roadmap of strategies launches, their purpose is twofold: help MIT develop and inform plans and procedures for mitigating and addressing heat on campus, and serve as a model for other universities and communities grappling with the same challenges. “This approach is the center of how we operate at MIT,” explains Director of Sustainability Julie Newman. “We seek to identify solutions for our own campus in a manner that others can learn from and potentially adapt for their own resiliency and climate planning purposes. We’re also looking to align with efforts at the city and state level.” By publishing the roadmap broadly, universities and municipalities can apply lessons and processes to their own spaces.When the updated Climate Resiliency Dashboard and Climate Resiliency and Adaptation Roadmap go live, it will mark the beginning of the next phase of work, rather than an end. “The dashboard is designed to present these impacts in a way everyone can understand so people across campus can respond and help us understand what is needed for them to continue to fulfill their role at MIT,” says Goldberg. Uncertainty plays a big role in resiliency planning, and the dashboard will reflect that. “This work is not something you ever say is done,” says Goldberg. “As information and data evolves, so does our work.”  More

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      in Energy

      AI method radically speeds predictions of materials’ thermal properties

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      It is estimated that about 70 percent of the energy generated worldwide ends up as waste heat.If scientists could better predict how heat moves through semiconductors and insulators, they could design more efficient power generation systems. However, the thermal properties of materials can be exceedingly difficult to model.The trouble comes from phonons, which are subatomic particles that carry heat. Some of a material’s thermal properties depend on a measurement called the phonon dispersion relation, which can be incredibly hard to obtain, let alone utilize in the design of a system.A team of researchers from MIT and elsewhere tackled this challenge by rethinking the problem from the ground up. The result of their work is a new machine-learning framework that can predict phonon dispersion relations up to 1,000 times faster than other AI-based techniques, with comparable or even better accuracy. Compared to more traditional, non-AI-based approaches, it could be 1 million times faster.This method could help engineers design energy generation systems that produce more power, more efficiently. It could also be used to develop more efficient microelectronics, since managing heat remains a major bottleneck to speeding up electronics.“Phonons are the culprit for the thermal loss, yet obtaining their properties is notoriously challenging, either computationally or experimentally,” says Mingda Li, associate professor of nuclear science and engineering and senior author of a paper on this technique.Li is joined on the paper by co-lead authors Ryotaro Okabe, a chemistry graduate student; and Abhijatmedhi Chotrattanapituk, an electrical engineering and computer science graduate student; Tommi Jaakkola, the Thomas Siebel Professor of Electrical Engineering and Computer Science at MIT; as well as others at MIT, Argonne National Laboratory, Harvard University, the University of South Carolina, Emory University, the University of California at Santa Barbara, and Oak Ridge National Laboratory. The research appears in Nature Computational Science.Predicting phononsHeat-carrying phonons are tricky to predict because they have an extremely wide frequency range, and the particles interact and travel at different speeds.A material’s phonon dispersion relation is the relationship between energy and momentum of phonons in its crystal structure. For years, researchers have tried to predict phonon dispersion relations using machine learning, but there are so many high-precision calculations involved that models get bogged down.“If you have 100 CPUs and a few weeks, you could probably calculate the phonon dispersion relation for one material. The whole community really wants a more efficient way to do this,” says Okabe.The machine-learning models scientists often use for these calculations are known as graph neural networks (GNN). A GNN converts a material’s atomic structure into a crystal graph comprising multiple nodes, which represent atoms, connected by edges, which represent the interatomic bonding between atoms.While GNNs work well for calculating many quantities, like magnetization or electrical polarization, they are not flexible enough to efficiently predict an extremely high-dimensional quantity like the phonon dispersion relation. Because phonons can travel around atoms on X, Y, and Z axes, their momentum space is hard to model with a fixed graph structure.To gain the flexibility they needed, Li and his collaborators devised virtual nodes.They create what they call a virtual node graph neural network (VGNN) by adding a series of flexible virtual nodes to the fixed crystal structure to represent phonons. The virtual nodes enable the output of the neural network to vary in size, so it is not restricted by the fixed crystal structure.Virtual nodes are connected to the graph in such a way that they can only receive messages from real nodes. While virtual nodes will be updated as the model updates real nodes during computation, they do not affect the accuracy of the model.“The way we do this is very efficient in coding. You just generate a few more nodes in your GNN. The physical location doesn’t matter, and the real nodes don’t even know the virtual nodes are there,” says Chotrattanapituk.Cutting out complexitySince it has virtual nodes to represent phonons, the VGNN can skip many complex calculations when estimating phonon dispersion relations, which makes the method more efficient than a standard GNN. The researchers proposed three different versions of VGNNs with increasing complexity. Each can be used to predict phonons directly from a material’s atomic coordinates.Because their approach has the flexibility to rapidly model high-dimensional properties, they can use it to estimate phonon dispersion relations in alloy systems. These complex combinations of metals and nonmetals are especially challenging for traditional approaches to model.The researchers also found that VGNNs offered slightly greater accuracy when predicting a material’s heat capacity. In some instances, prediction errors were two orders of magnitude lower with their technique.A VGNN could be used to calculate phonon dispersion relations for a few thousand materials in just a few seconds with a personal computer, Li says.This efficiency could enable scientists to search a larger space when seeking materials with certain thermal properties, such as superior thermal storage, energy conversion, or superconductivity.Moreover, the virtual node technique is not exclusive to phonons, and could also be used to predict challenging optical and magnetic properties.In the future, the researchers want to refine the technique so virtual nodes have greater sensitivity to capture small changes that can affect phonon structure.“Researchers got too comfortable using graph nodes to represent atoms, but we can rethink that. Graph nodes can be anything. And virtual nodes are a very generic approach you could use to predict a lot of high-dimensional quantities,” Li says.“The authors’ innovative approach significantly augments the graph neural network description of solids by incorporating key physics-informed elements through virtual nodes, for instance, informing wave-vector dependent band-structures and dynamical matrices,” says Olivier Delaire, associate professor in the Thomas Lord Department of Mechanical Engineering and Materials Science at Duke University, who was not involved with this work. “I find that the level of acceleration in predicting complex phonon properties is amazing, several orders of magnitude faster than a state-of-the-art universal machine-learning interatomic potential. Impressively, the advanced neural net captures fine features and obeys physical rules. There is great potential to expand the model to describe other important material properties: Electronic, optical, and magnetic spectra and band structures come to mind.”This work is supported by the U.S. Department of Energy, National Science Foundation, a Mathworks Fellowship, a Sow-Hsin Chen Fellowship, the Harvard Quantum Initiative, and the Oak Ridge National Laboratory. More

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      in Environment

      Study finds health risks in switching ships from diesel to ammonia fuel

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      As container ships the size of city blocks cross the oceans to deliver cargo, their huge diesel engines emit large quantities of air pollutants that drive climate change and have human health impacts. It has been estimated that maritime shipping accounts for almost 3 percent of global carbon dioxide emissions and the industry’s negative impacts on air quality cause about 100,000 premature deaths each year.Decarbonizing shipping to reduce these detrimental effects is a goal of the International Maritime Organization, a U.N. agency that regulates maritime transport. One potential solution is switching the global fleet from fossil fuels to sustainable fuels such as ammonia, which could be nearly carbon-free when considering its production and use.But in a new study, an interdisciplinary team of researchers from MIT and elsewhere caution that burning ammonia for maritime fuel could worsen air quality further and lead to devastating public health impacts, unless it is adopted alongside strengthened emissions regulations.Ammonia combustion generates nitrous oxide (N2O), a greenhouse gas that is about 300 times more potent than carbon dioxide. It also emits nitrogen in the form of nitrogen oxides (NO and NO2, referred to as NOx), and unburnt ammonia may slip out, which eventually forms fine particulate matter in the atmosphere. These tiny particles can be inhaled deep into the lungs, causing health problems like heart attacks, strokes, and asthma.The new study indicates that, under current legislation, switching the global fleet to ammonia fuel could cause up to about 600,000 additional premature deaths each year. However, with stronger regulations and cleaner engine technology, the switch could lead to about 66,000 fewer premature deaths than currently caused by maritime shipping emissions, with far less impact on global warming.“Not all climate solutions are created equal. There is almost always some price to pay. We have to take a more holistic approach and consider all the costs and benefits of different climate solutions, rather than just their potential to decarbonize,” says Anthony Wong, a postdoc in the MIT Center for Global Change Science and lead author of the study.His co-authors include Noelle Selin, an MIT professor in the Institute for Data, Systems, and Society and the Department of Earth, Atmospheric and Planetary Sciences (EAPS); Sebastian Eastham, a former principal research scientist who is now a senior lecturer at Imperial College London; Christine Mounaïm-Rouselle, a professor at the University of Orléans in France; Yiqi Zhang, a researcher at the Hong Kong University of Science and Technology; and Florian Allroggen, a research scientist in the MIT Department of Aeronautics and Astronautics. The research appears this week in Environmental Research Letters.Greener, cleaner ammoniaTraditionally, ammonia is made by stripping hydrogen from natural gas and then combining it with nitrogen at extremely high temperatures. This process is often associated with a large carbon footprint. The maritime shipping industry is betting on the development of “green ammonia,” which is produced by using renewable energy to make hydrogen via electrolysis and to generate heat.“In theory, if you are burning green ammonia in a ship engine, the carbon emissions are almost zero,” Wong says.But even the greenest ammonia generates nitrous oxide (N2O), nitrogen oxides (NOx) when combusted, and some of the ammonia may slip out, unburnt. This nitrous oxide would escape into the atmosphere, where the greenhouse gas would remain for more than 100 years. At the same time, the nitrogen emitted as NOx and ammonia would fall to Earth, damaging fragile ecosystems. As these emissions are digested by bacteria, additional N2O  is produced.NOx and ammonia also mix with gases in the air to form fine particulate matter. A primary contributor to air pollution, fine particulate matter kills an estimated 4 million people each year.“Saying that ammonia is a ‘clean’ fuel is a bit of an overstretch. Just because it is carbon-free doesn’t necessarily mean it is clean and good for public health,” Wong says.A multifaceted modelThe researchers wanted to paint the whole picture, capturing the environmental and public health impacts of switching the global fleet to ammonia fuel. To do so, they designed scenarios to measure how pollutant impacts change under certain technology and policy assumptions.From a technological point of view, they considered two ship engines. The first burns pure ammonia, which generates higher levels of unburnt ammonia but emits fewer nitrogen oxides. The second engine technology involves mixing ammonia with hydrogen to improve combustion and optimize the performance of a catalytic converter, which controls both nitrogen oxides and unburnt ammonia pollution.They also considered three policy scenarios: current regulations, which only limit NOx emissions in some parts of the world; a scenario that adds ammonia emission limits over North America and Western Europe; and a scenario that adds global limits on ammonia and NOx emissions.The researchers used a ship track model to calculate how pollutant emissions change under each scenario and then fed the results into an air quality model. The air quality model calculates the impact of ship emissions on particulate matter and ozone pollution. Finally, they estimated the effects on global public health.One of the biggest challenges came from a lack of real-world data, since no ammonia-powered ships are yet sailing the seas. Instead, the researchers relied on experimental ammonia combustion data from collaborators to build their model.“We had to come up with some clever ways to make that data useful and informative to both the technology and regulatory situations,” he says.A range of outcomesIn the end, they found that with no new regulations and ship engines that burn pure ammonia, switching the entire fleet would cause 681,000 additional premature deaths each year.“While a scenario with no new regulations is not very realistic, it serves as a good warning of how dangerous ammonia emissions could be. And unlike NOx, ammonia emissions from shipping are currently unregulated,” Wong says.However, even without new regulations, using cleaner engine technology would cut the number of premature deaths down to about 80,000, which is about 20,000 fewer than are currently attributed to maritime shipping emissions. With stronger global regulations and cleaner engine technology, the number of people killed by air pollution from shipping could be reduced by about 66,000.“The results of this study show the importance of developing policies alongside new technologies,” Selin says. “There is a potential for ammonia in shipping to be beneficial for both climate and air quality, but that requires that regulations be designed to address the entire range of potential impacts, including both climate and air quality.”Ammonia’s air quality impacts would not be felt uniformly across the globe, and addressing them fully would require coordinated strategies across very different contexts. Most premature deaths would occur in East Asia, since air quality regulations are less stringent in this region. Higher levels of existing air pollution cause the formation of more particulate matter from ammonia emissions. In addition, shipping volume over East Asia is far greater than elsewhere on Earth, compounding these negative effects.In the future, the researchers want to continue refining their analysis. They hope to use these findings as a starting point to urge the marine industry to share engine data they can use to better evaluate air quality and climate impacts. They also hope to inform policymakers about the importance and urgency of updating shipping emission regulations.This research was funded by the MIT Climate and Sustainability Consortium. More