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      in Environment

      MIT climate and sustainability interns consider aviation emissions and climate change

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      Over 600 MIT students are traveling abroad with the MIT International Science and Technology Initiatives (MISTI) to intern, research, and work in organizations across 25 countries this summer. Twenty percent of the students were placed in areas related to climate and sustainability.

      Through MISTI, hundreds of MIT students travel abroad each summer to intern in companies, universities, governments, and nongovernmental organizations. Since 2018, around 20 percent of the internships and research experiences have been in areas related to climate and sustainability. MISTI has been working to increase the number of interns working on these projects by increasing the number of hosts and available grants, as well as connecting with other labs, departments, and centers across MIT to support students’ global experiences.

      For the first time this year, MISTI developed pre-departure sessions intended to help students reflect on their experiences in the wider context of sustainability and climate change. Around 90 students were invited to participate in a Canvas course and an in-person session with guest speakers. In the Canvas session, students were asked to calculate the carbon footprint of their flight to their MISTI destination and compare the results to other common daily activities. Four out of five of them expressed that the level of emissions from their flights was higher, or much higher, than they previously thought. Half of the students expressed that this was the first time they thought about their flight emissions for the summer. The students were then directed to the MIT Climate Portal website and asked to reflect on the impact of carbon dioxide emissions on the climate and the effects of climate change on economically developing countries. The Canvas exercise concluded with readings and reflections on what can be done to address the climate crisis.

      The in-person session featured David Hsu, associate professor of urban and environmental planning and co-chair of the Campus Fast Forward working group on climate education, who presented his research and work on flight emissions. He emphasized the high impact of aviation on carbon dioxide emissions and how emissions are unevenly distributed on a global scale, based on income levels and per capita bases. A small group of travelers account for most of the emissions, which is also true in academic settings where a small number of travelers have a much higher carbon footprint. Hsu also explained the School of Architecture and Planning climate action plan and how it addresses faculty and student travel. “I know it’s hard. If we at MIT want to be leaders in this area, talking about it is not enough,” he said. “We have to act. We cannot be models just by doing research; we have to be role models at all levels. Faculty, staff, and students have to change their flight habits.”

      Having completed the climate and sustainability training, Favianna Colón Irizarry, a rising second-year majoring in chemical and biological engineering, explains, “to minimize our carbon footprint, we are taught to eat consciously and use environmentally friendly products. What we are not taught is that this alone will not make a difference; we ought to sacrifice more, like flying selectively and meaningfully, to truly make an impact. MISTI’s Climate and Sustainability helped me recognize this, as well as prepare me for how I choose to proceed in my future green endeavors.”

      Also during the session, rising seniors Anushree Chaudhuri and Melissa Stok, the leads for the MIT Student Sustainability Coalition, presented their work around coordinating efforts among students and the vast landscape of groups, organizations, and entities at the Institute. They invited all interested students to join and reach out to any of the entities that could be a good fit for their interests. Chaudhuri reflected afterwards, “Sustainability is inherently interdisciplinary. Every MIT student can incorporate sustainability into their work, regardless of major, class year, or interests! I was excited to join my SSC co-lead, Melissa, in speaking with a diverse group of MISTI interns about how to explore sustainability-related academic, extracurricular, professional, and experiential opportunities at MIT and beyond. These students come from many different disciplines, so it was incredibly heartening to hear that they are all pursuing a climate-related project abroad this summer.”

      Eduardo Rivera, MISTI’s coordinator for climate and sustainability expressed that “educational experiences abroad are a fundamental part of MIT’s mission to foster global leaders to tackle the climate crisis. This summer, more than 110 students will be working around the world in solar and wind technologies, carbon capture, climate adaptation and urban planning, sustainable concrete, electric mobility, among others. We are using this opportunity to expand on the reflection part of the experiential learning cycle. The goal of these pre-departure sessions is to raise awareness and help our students reflect on the impact of their everyday activities on the climate, and to also give them resources to learn and act thoughtfully. We hope they will not only become conscious travelers, but also agents for change.”

      “This year’s climate and sustainability pre-departure training were pilot sessions, and the goal is to expand this learning experience to all MISTI students, not just those working in the fields of climate and sustainability. This will be a unique opportunity to raise awareness and expand the knowledge to over 1,000 of our students as they travel to more than 40 countries across the globe,” explains Abby MacKenzie, MIT-India coordinator who co-developed the pre-departure sessions. More

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      in Energy

      Panel addresses technologies needed for a net-zero future

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      Five speakers at a recent public panel discussion hosted by the MIT Energy Initiative (MITEI) and introduced by Deputy Director for Science and Technology Robert Stoner tackled one of the thorniest, yet most critical, questions facing the world today: How can we achieve the ambitious goals set by governments around the globe, including the United States, to reach net zero emissions of greenhouse gases by mid-century?

      While the challenges are great, the panelists agreed, there is reason for optimism that these technological challenges can be solved. More uncertain, some suggested, are the social, economic, and political hurdles to bringing about the needed innovations.

      The speakers addressed areas where new or improved technologies or systems are needed if these ambitious goals are to be achieved. Anne White, aassociate provost and associate vice president for research administration and a professor of nuclear science and engineering at MIT, moderated the panel discussion. She said that achieving the ambitious net-zero goal “has to be accomplished by filling some gaps, and going after some opportunities.” In addressing some of these needs, she said the five topics chosen for the panel discussion were “places where MIT has significant expertise, and progress is already ongoing.”

      First of these was the heating and cooling of buildings. Christoph Reinhart, a professor of architecture and director of the Building Technology Program, said that currently about 1 percent of existing buildings are being retrofitted each year for energy efficiency and conversion from fossil-fuel heating systems to efficient electric ones — but that is not nearly enough to meet the 2050 net-zero target. “It’s an enormous task,” he said. To meet the goals, he said, would require increasing the retrofitting rate to 5 percent per year, and to require all new construction to be carbon neutral as well.

      Reinhart then showed a series of examples of how such conversions could take place using existing solar and heat pump technology, and depending on the configuration, how they could provide a payback to the homeowner within 10 years or less. However, without strong policy incentives the initial cost outlay for such a system, on the order of $50,000, is likely to put conversions out of reach of many people. Still, a recent survey found that 30 percent of homeowners polled said they would accept installation at current costs. While there is government money available for incentives for others, “we have to be very clever on how we spend all this money … and make sure that everybody is basically benefiting.”

      William Green, a professor of chemical engineering, spoke about the daunting challenge of bringing aviation to net zero. “More and more people like to travel,” he said, but that travel comes with carbon emissions that affect the climate, as well as air pollution that affects human health. The economic costs associated with these emissions, he said, are estimated at $860 per ton of jet fuel used — which is very close to the cost of the fuel itself. So the price paid by the airlines, and ultimately by the passengers, “is only about half of the true cost to society, and the other half is being borne by all of us, by the fact that it’s affecting the climate and it’s causing medical problems for people.”

      Eliminating those emissions is a major challenge, he said. Virtually all jet fuel today is fossil fuel, but airlines are starting to incorporate some biomass-based fuel, derived mostly from food waste. But even these fuels are not carbon-neutral, he said. “They actually have pretty significant carbon intensity.”

      But there are possible alternatives, he said, mostly based on using hydrogen produced by clean electricity, and making fuels out of that hydrogen by reacting it, for example, with carbon dioxide. This could indeed produce a carbon-neutral fuel that existing aircraft could use, but the process is costly, requiring a great deal of hydrogen, and ways of concentrating carbon dioxide. Other viable options also exist, but all would add significant expense, at least with present technology. “It’s going to cost a lot more for the passengers on the plane,” Green said, “But the society will benefit from that.”

      Increased electrification of heating and transportation in order to avoid the use of fossil fuels will place major demands on the existing electric grid systems, which have to perform a constant delicate balancing of production with demand. Anuradha Annaswamy, a senior research scientist in MIT’s mechanical engineering department, said “the electric grid is an engineering marvel.” In the United States it consists of 300,000 miles of transmission lines capable of carrying 470,000 megawatts of power.

      But with a projected doubling of energy from renewable sources entering the grid by 2030, and with a push to electrify everything possible — from transportation to buildings to industry — the load is not only increasing, but the patterns of both energy use and production are changing. Annaswamy said that “with all these new assets and decision-makers entering the picture, the question is how you can use a more sophisticated information layer that coordinates how all these assets are either consuming or producing or storing energy, and have that information layer coexist with the physical layer to make and deliver electricity in all these ways. It’s really not a simple problem.”

      But there are ways of addressing these complexities. “Certainly, emerging technologies in power electronics and control and communication can be leveraged,” she said. But she added that “This is not just a technology problem, really, it is something that requires technologists, economists, and policymakers to all come together.”

      As for industrial processes, Bilge Yildiz, a professor of nuclear science and engineering and materials science and engineering, said that “the synthesis of industrial chemicals and materials constitutes about 33 percent of global CO2 emissions at present, and so our goal is to decarbonize this difficult sector.” About half of all these industrial emissions come from the production of just four materials: steel, cement, ammonia, and ethylene, so there is a major focus of research on ways to reduce their emissions.

      Most of the processes to make these materials have changed little for more than a century, she said, and they are mostly heat-based processes that involve burning a lot of fossil fuel. But the heat can instead be provided from renewable electricity, which can also be used to drive electrochemical reactions in some cases as a substitute for the thermal reactions. Already, there are processes for making cement and steel that produce only about half the present carbon dioxide (CO2) emissions.

      The production of ammonia, which is widely used in fertilizer and other bulk chemicals, accounts for more greenhouse gas emissions than any other industrial source. The present thermochemical process could be replaced by an electrochemical process, she said. Similarly, the production of ethylene, as a feedstock for plastics and other materials, is the second-highest emissions producer, with three tons of carbon dioxide released for every ton of ethylene produced. Again, an electrochemical alternative method exists, but needs to be improved to be cost competitive.

      As the world moves toward electrification of industrial processes to eliminate fossil fuels, the need for emissions-free sources of electricity will continue to increase. One very promising potential addition to the range of carbon-free generation sources is fusion, a field in which MIT is a leader in developing a particularly promising technology that takes advantage of the unique properties of high-temperature superconducting (HTS) materials.

      Dennis Whyte, the director of MIT’s Plasma Science and Fusion Center, pointed out that despite global efforts to reduce CO2 emissions, “we use exactly the same percentage of carbon-based products to generate energy as 10 years ago, or 20 years ago.” To make a real difference in global emissions, “we need to make really massive amounts of carbon-free energy.”

      Fusion, the process that powers the sun, is a particularly promising pathway, because the fuel, derived from water, is virtually inexhaustible. By using recently developed HTS material to generate the powerful magnetic fields needed to produce a sustained fusion reaction, the MIT-led project, which led to a spinoff company called Commonwealth Fusion Systems, was able to radically reduce the required size of a fusion reactor, Whyte explained. Using this approach, the company, in collaboration with MIT, expects to have a fusion system that produces net energy by the middle of this decade, and be ready to build a commercial plant to produce power for the grid early in the next. Meanwhile, at least 25 other private companies are also attempting to commercialize fusion technology. “I think we can take some credit for helping to spawn what is essentially now a new industry in the United States,” Whyte said.

      Fusion offers the potential, along with existing solar and wind technologies, to provide the emissions-free power the world needs, Whyte says, but that’s only half the problem, the other part being how to get that power to where it’s needed, when it’s needed. “How do we adapt these new energy sources to be as compatible as possible with everything that we have already in terms of energy delivery?”

      Part of the way to find answers to that, he suggested, is more collaborative work on these issues that cut across disciplines, as well as more of the kinds of cross-cutting conversations and interactions that took place in this panel discussion. More

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      in Environment

      MIT engineering students take on the heat of Miami

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      Think back to the last time you had to wait for a bus. How miserable were you? If you were in Boston, your experience might have included punishing wind and icy sleet — or, more recently, a punch of pollen straight to the sinuses. But in Florida’s Miami-Dade County, where the effects of climate change are both drastic and intensifying, commuters have to contend with an entirely different set of challenges: blistering temperatures and scorching humidity, making long stints waiting in the sun nearly unbearable.

      One of Miami’s most urgent transportation needs is shared by car-clogged Boston: coaxing citizens to use the municipal bus network, rather than the emissions-heavy individual vehicles currently contributing to climate change. But buses can be a tough sell in a sunny city where humidity hovers between 60 and 80 percent year-round. 

      Enter MIT’s Department of Electrical Engineering and Computer Science (EECS) and the MIT Priscilla King Gray (PKG) Public Service Center. The result of close collaboration between the two organizations, class 6.900 (Engineering For Impact) challenges EECS students to apply their engineering savvy to real-world problems beyond the MIT campus.

      This spring semester, the real-world problem was heat. 

      Miami-Dade County Department of Transportation and Public Works Chief Innovation Officer Carlos Cruz-Casas explains: “We often talk about the city we want to live in, about how the proper mix of public transportation, on-demand transit, and other mobility solutions, such as e-bikes and e-scooters, could help our community live a car-light life. However, none of this will be achievable if the riders are not comfortable when doing so.” 

      “When people think of South Florida and climate change, they often think of sea level rise,” says Juan Felipe Visser, deputy director of equity and engagement within the Office of the Mayor in Miami-Dade. “But heat really is the silent killer. So the focus of this class, on heat at bus stops, is very apt.” With little tree cover to give relief at some of the hottest stops, Miami-Dade commuters cluster in tiny patches of shade behind bus stops, sometimes giving up when the heat becomes unbearable. 

      A more conventional electrical engineering course might use temperature monitoring as an abstract example, building sample monitors in isolation and grading them as a merely academic exercise. But Professor Joel Volman, EECS faculty head of electrical engineering, and Joe Steinmeyer, senior lecturer in EECS, had something more impactful in mind.

      “Miami-Dade has a large population of people who are living in poverty, undocumented, or who are otherwise marginalized,” says Voldman. “Waiting, sometimes for a very long time, in scorching heat for the bus is just one aspect of how a city population can be underserved, but by measuring patterns in how many people are waiting for a bus, how long they wait, and in what conditions, we can begin to see where services are not keeping up with demand.”

      Only after that gap is quantified can the work of city and transportation planners begin, Cruz-Casas explains: “We needed to quantify the time riders are exposed to extreme heat and prioritize improvements, including on-time performance improvements, increasing service frequency, or looking to enhance the tree canopy near the bus stop.” 

      Quantifying that time — and the subjective experience of the wait — proved tricky, however. With over 7,500 bus stops along 101 bus routes, Miami-Dade’s transportation network presents a considerable data-collection challenge. A network of physical temperature monitors could be useful, but only if it were carefully calibrated to meet the budgetary, environmental, privacy, and implementation requirements of the city. But how do you work with city officials — not to mention all of bus-riding Miami — from over 2,000 miles away? 

      This is where the PKG Center comes in. “We are a hub and a connector and facilitator of best practices,” explains Jill Bassett, associate dean and director of the center, who worked with Voldman and Steinmeyer to find a municipal partner organization for the course. “We bring knowledge of current pedagogy around community-engaged learning, which includes: help with framing a partnership that centers community-identified concerns and is mutually beneficial; identifying and learning from a community partner; talking through ways to build in opportunities for student learners to reflect on power dynamics, reciprocity, systems thinking, long-term planning, continuity, ethics, all the types of things that come up with this kind of shared project.”

      Through a series of brainstorming conversations, Bassett helped Voldman and Steinmeyer structure a well-defined project plan, as Cruz-Casas weighed in on the county’s needed technical specifications (including affordability, privacy protection, and implementability).

      “This course brings together a lot of subject area experts,” says Voldman. “We brought in guest lecturers, including Abby Berenson from the Sloan Leadership Center, to talk about working in teams; engineers from BOSE to talk about product design, certification, and environmental resistance; the co-founder and head of engineering from MIT spinout Butlr to talk about their low-power occupancy sensor; Tony Hu from MIT IDM [Integrated Design and Management] to talk about industrial design; and Katrina LaCurts from EECS to talk about communications and networking.”

      With the support of two generous donations and a gift of software from Altium, 6.900 developed into a hands-on exercise in hardware/software product development with a tangible goal in sight: build a better bus monitor.

      The challenges involved in this undertaking became apparent as soon as the 6.900 students began designing their monitors. “The most challenging requirement to meet was that the monitor be able to count how many people were waiting — and for how long they’d been standing there — while still maintaining privacy,” says Fabian Velazquez ’23 a recent EECS graduate. The task was complicated by commuters’ natural tendency to stand where the shade goes — whether beneath a tree or awning or snaking against a nearby wall in a line — rather than directly next to the bus sign or inside the bus shelter. “Accurately measuring people count with a camera — the most straightforward choice — is already quite difficult since you have to incorporate machine learning to identify which objects in frame are people. Maintaining privacy added an extra layer of constraint … since there is no guarantee the collected data wouldn’t be vulnerable.”

      As the groups weighed various privacy-preserving options, including lidar, radar, and thermal imaging, the class realized that Wi-Fi “sniffers,” which count the number of Wi-Fi enabled signals in the immediate area, were their best option to count waiting passengers. “We were all excited and ready for this amazing, answer-to-all-our-problems radar sensor to count people,” says Velasquez. “That component was extremely complex, however, and the complexity would have ultimately made my team use a lot of time and resources to integrate with our system. We also had a short time-to-market for this system we developed. We made the trade-off of complexity for robustness.” 

      The weather also posed its own set of challenges. “Environmental conditions were big factors on the structure and design of our devices,” says Yong Yan (Crystal) Liang, a rising junior majoring in EECS. “We incorporated humidity and temperature sensors into our data to show the weather at individual stops. Additionally, we also considered how our enclosure may be affected by extreme heat or potential hurricanes.”

      The heat variable proved problematic in multiple ways. “People detection was especially difficult, for in the Miami heat, thermal cameras may not be able to distinguish human body temperature from the surrounding air temperature, and the glare of the sun off of other surfaces in the area makes most forms of imaging very buggy,” says Katherine Mohr ’23. “My team had considered using mmWave sensors to get around these constraints, but we found the processing to be too difficult, and (like the rest of the class), we decided to only move forward with Wi-Fi/BLE [Bluetooth Low Energy] sniffers.”

      The most valuable component of the new class may well have been the students’ exposure to real-world hardware/software engineering product development, where limitations on time and budget always exist, and where client requests must be carefully considered.  “Having an actual client to work with forced us to learn how to turn their wants into more specific technical specifications,” says Mohr. “We chose deliverables each week to complete by Friday, prioritizing tasks which would get us to a minimum viable product, as well as tasks that would require extra manufacturing time, like designing the printed-circuit board and enclosure.”

      Play video

      Joel Voldman, who co-designed 6.900 (Engineering For Impact) with Joe Steinmeyer and MIT’s Priscilla King Gray (PKG) Public Service Center, describes how the course allowed students help develop systems for the public good. Voldman is the winner of the 2023 Teaching with Digital Technology Award, which is co-sponsored by MIT Open Learning and the Office of the Vice Chancellor. Video: MIT Open Learning

      Crystal Liang counted her conversations with city representatives as among her most valuable 6.900 experiences. “We generated a lot of questions and were able to communicate with the community leaders of this project from Miami-Dade, who made time to answer all of them and gave us ideas from the goals they were trying to achieve,” she reports. “This project gave me a new perspective on problem-solving because it taught me to see things from the community members’ point of view.” Some of those community leaders, including Marta Viciedo, co-founder of Transit Alliance Miami, joined the class’s final session on May 16 to review the students’ proposed solutions. 

      The students’ thoughtful approach paid off when it was time to present the heat monitors to the class’s client. In a group conference call with Miami-Dade officials toward the end of the semester, the student teams shared their findings and the prototypes they’d created, along with videos of the devices at work. Juan Felipe Visser was among those in attendance. “This is a lot of work,” he told the students following their presentation. “So first of all, thank you for doing that, and for presenting to us. I love the concept. I took the bus this morning, as I do every morning, and was battered by the sun and the heat. So I personally appreciated the focus.” 

      Cruz-Casas agreed: “I am pleasantly surprised by the diverse approach the students are taking. We presented a challenge, and they have responded to it and managed to think beyond the problem at hand. I’m very optimistic about how the outcomes of this project will have a long-lasting impact for our community. At a minimum, I’m thinking that the more awareness we raise about this topic, the more opportunities we have to have the brightest minds seeking for a solution.”

      The creators of 6.900 agree, and hope that their class helps more MIT engineers to broaden their perspective on the meaning and application of their work. 

      “We are really excited about students applying their skills within a real-world, complex environment that will impact real people,” says Bassett. “We are excited that they are learning that it’s not just the design of technology that matters, but that climate; environment and built environment; and issues around socioeconomics, race, and equity, all come into play. There are layers and layers to the creation and deployment of technology in a demographically diverse multilingual community that is at the epicenter of climate change.” More

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      in Environment

      Megawatt electrical motor designed by MIT engineers could help electrify aviation

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      Aviation’s huge carbon footprint could shrink significantly with electrification. To date, however, only small all-electric planes have gotten off the ground. Their electric motors generate hundreds of kilowatts of power. To electrify larger, heavier jets, such as commercial airliners, megawatt-scale motors are required. These would be propelled by hybrid or turbo-electric propulsion systems where an electrical machine is coupled with a gas turbine aero-engine.

      To meet this need, a team of MIT engineers is now creating a 1-megawatt motor that could be a key stepping stone toward electrifying larger aircraft. The team has designed and tested the major components of the motor, and shown through detailed computations that the coupled components can work as a whole to generate one megawatt of power, at a weight and size competitive with current small aero-engines.

      For all-electric applications, the team envisions the motor could be paired with a source of electricity such as a battery or a fuel cell. The motor could then turn the electrical energy into mechanical work to power a plane’s propellers. The electrical machine could also be paired with a traditional turbofan jet engine to run as a hybrid propulsion system, providing electric propulsion during certain phases of a flight.

      “No matter what we use as an energy carrier — batteries, hydrogen, ammonia, or sustainable aviation fuel — independent of all that, megawatt-class motors will be a key enabler for greening aviation,” says Zoltan Spakovszky, the T. Wilson Professor in Aeronautics and the Director of the Gas Turbine Laboratory (GTL) at MIT, who leads the project.

      Spakovszky and members of his team, along with industry collaborators, will present their work at a special session of the American Institute of Aeronautics and Astronautics – Electric Aircraft Technologies Symposium (EATS) at the Aviation conference in June.

      The MIT team is composed of faculty, students, and research staff from GTL and the MIT Laboratory for Electromagnetic and Electronic Systems: Henry Andersen Yuankang Chen, Zachary Cordero, David Cuadrado,  Edward Greitzer, Charlotte Gump, James Kirtley, Jr., Jeffrey Lang, David Otten, David Perreault, and Mohammad Qasim,  along with Marc Amato of Innova-Logic LLC. The project is sponsored by Mitsubishi Heavy Industries (MHI).

      Heavy stuff

      To prevent the worst impacts from human-induced climate change, scientists have determined that global emissions of carbon dioxide must reach net zero by 2050. Meeting this target for aviation, Spakovszky says, will require “step-change achievements” in the design of unconventional aircraft, smart and flexible fuel systems, advanced materials, and safe and efficient electrified propulsion. Multiple aerospace companies are focused on electrified propulsion and the design of megawatt-scale electric machines that are powerful and light enough to propel passenger aircraft.

      “There is no silver bullet to make this happen, and the devil is in the details,” Spakovszky says. “This is hard engineering, in terms of co-optimizing individual components and making them compatible with each other while maximizing overall performance. To do this means we have to push the boundaries in materials, manufacturing, thermal management, structures and rotordynamics, and power electronics”

      Broadly speaking, an electric motor uses electromagnetic force to generate motion. Electric motors, such as those that power the fan in your laptop, use electrical energy — from a battery or power supply — to generate a magnetic field, typically through copper coils. In response, a magnet, set near the coils, then spins in the direction of the generated field and can then drive a fan or propeller.

      Electric machines have been around for over 150 years, with the understanding that, the bigger the appliance or vehicle, the larger the copper coils  and the magnetic rotor, making the machine heavier. The more power the electrical machine generates, the more heat it produces, which requires additional elements to keep the components cool — all of which can take up space and add significant weight to the system, making it challenging for airplane applications.

      “Heavy stuff doesn’t go on airplanes,” Spakovszky says. “So we had to come up with a compact, lightweight, and powerful architecture.”

      Good trajectory

      As designed, the MIT electric motor and power electronics are each about the size of a checked suitcase weighing less than an adult passenger.

      The motor’s main components are: a high-speed rotor, lined with an array of magnets with varying orientation of polarity; a compact low-loss stator that fits inside the rotor and contains an intricate array of copper windings; an advanced heat exchanger that keeps the components cool while transmitting the torque of the machine; and a distributed power electronics system, made from 30 custom-built circuit boards, that precisely change the currents running through each of the stator’s copper windings, at high frequency.

      “I believe this is the first truly co-optimized integrated design,” Spakovszky says. “Which means we did a very extensive design space exploration where all considerations from thermal management, to rotor dynamics, to power electronics and electrical machine architecture were assessed in an integrated way to find out what is the best possible combination to get the required specific power at one megawatt.”

      As a whole system, the motor is designed such that the distributed circuit boards are close coupled with the electrical machine to minimize transmission loss and to allow effective air cooling through the integrated heat exchanger.

      “This is a high-speed machine, and to keep it rotating while creating torque, the magnetic fields have to be traveling very quickly, which we can do through our circuit boards switching at high frequency,” Spakovszky says.

      To mitigate risk, the team has built and tested each of the major components individually, and shown that they can operate as designed and at conditions exceeding normal operational demands. The researchers plan to assemble the first fully working electric motor, and start testing it in the fall.

      “The electrification of aircraft has been on a steady rise,” says Phillip Ansell, director of the Center for Sustainable Aviation at the University of Illinois Urbana-Champaign, who was not involved in the project. “This group’s design uses a wonderful combination of conventional and cutting-edge methods for electric machine development, allowing it to offer both robustness and efficiency to meet the practical needs of aircraft of the future.”

      Once the MIT team can demonstrate the electric motor as a whole, they say the design could power regional aircraft and could also be a companion to conventional jet engines, to enable hybrid-electric propulsion systems. The team also envision that multiple one-megawatt motors could power multiple fans distributed along the wing on future aircraft configurations. Looking ahead, the foundations of the one-megawatt electrical machine design could potentially be scaled up to multi-megawatt motors, to power larger passenger planes.

      “I think we’re on a good trajectory,” says Spakovszky, whose group and research have focused on more than just gas turbines. “We are not electrical engineers by training, but addressing the 2050 climate grand challenge is of utmost importance; working with electrical engineering faculty, staff and students for this goal can draw on MIT’s breadth of technologies so the whole is greater than the sum of the parts. So we are reinventing ourselves in new areas. And MIT gives you the opportunity to do that.” More

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      in Energy

      Will the charging networks arrive in time?

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      For many owners of electric vehicles (EVs), or for prospective EV owners, a thorny problem is where to charge them. Even as legacy automakers increasingly invest in manufacturing more all-electric cars and trucks, there is not a dense network of charging stations serving many types of vehicles, which would make EVs more convenient to use.

      “We’re going to have the ability to produce and deliver millions of EVs,” said MIT Professor Charles Fine at the final session this semester of the MIT Mobility Forum. “It’s not clear we’re going to have the ability to charge them. That’s a huge, huge mismatch.”

      Indeed, making EV charging stations as ubiquitous as gas stations could spur a major transition within the entire U.S. vehicle fleet. While the automaker Tesla has built a network of almost 2,000 charging stations across the U.S., and might make some interoperable with other makes of vehicles, independent companies trying to develop a business out of it are still trying to gain significant traction.

      “They don’t have a business model that works yet,” said Fine, the Chrysler Leaders for Global Operations Professor of Management at the MIT Sloan School of Management, speaking of startup firms. “They haven’t figured out their supply chains. They haven’t figured out the customer value proposition. They haven’t figured out their technology standards. It’s a very, very immature domain.”

      The May 12 event drew nearly 250 people as well as an online audience. The MIT Mobility Forum is a weekly set of talks and discussions during the academic year, ranging widely across the field of transportation and design. It is hosted by the MIT Mobility Initiative, which works to advance sustainable, accessible, and safe forms of transportation.

      Fine is a prominent expert in the areas of operations strategy, entrepreneurship, and supply chain management. He has been at MIT Sloan for over 30 years; from 2015 to 2022, he also served as the founding president, dean, and CEO of the Asia School of Business in Kuala Lumpur, Malaysia, a collaboration between MIT Sloan and Bank Negara Malaysia. Fine is also author of “Faster, Smarter, Greener: The Future of the Car and Urban Mobility” (MIT Press, 2017).

      In Fine’s remarks, he discussed the growth stages of startup companies, highlighting three phases where firms try to “nail it, scale it, and sail it” — that is, figure out the concept and workability of their enterprise, try to expand it, and then operate as a larger company. The charging-business startups are still somewhere within the first of these phases.

      At the same time, the established automakers have announced major investments in EVs — a collective $860 billion over the next decade, Fine noted. Among others, Ford says it will invest $50 billion in EV production by 2026; General Motors plans to spend $35 billion on EVs by 2025; and Toyota has announced it will invest $35 billion in EV manufacturing by 2030.

      With all these vehicles potentially coming to market, Fine suggested, the crux of the issue is a kind of “chicken and egg” problem between EVs and the network needed to support them.

      “If you’re a startup company in the charging business, if there aren’t many EVs out there, you’re not going to be making much money, and that doesn’t give you the capital to continue to invest and grow,” Fine said. “So, they need to wait until they have revenue before they can grow further. On the other hand, why should anybody buy an electric car if they don’t think they’re going to be able to charge it?”

      Those living in single-family homes can install chargers. But many others are not in that situation, Fine noted: “For people who don’t have fixed parking spaces and have to rely on the public network, there is this chicken-and-egg problem. They can’t buy an EV unless they know how they’re going to be able to charge it, and charging companies can’t build out their networks unless they know how they’re going to get their revenue.”

      The event featured a question-and-answer session and audience discussion, with a range of questions, and comments from some industry veterans, including Robin Chase SM ’86, the co-founder and former CEO of Zipcar. She expressed some optimism that startup charging companies will be able to get traction in the nascent market before long.

      “The right companies can learn very fast,” Chase said. “There’s no reason why they can’t correct those scaling problems in short-ish order.”

      In answer to other audience questions, Fine noted some of the challenges that will have to be addressed by independent charging firms, such as unified standards and interoperability among automakers and charging stations.

      “For a driver to have to have six different apps, or [their] car doesn’t fit in the plug here or there, or my software doesn’t talk to my credit card … connectivity, standards, technical issues need to be worked out as well,” Fine said.

      There are also varying regulatory issues, including grid policies and what consumers can be billed for, which have to be worked out on a state-by-state basis, meaning that even modest-size startups will have to have knowledgeable and productive legal departments.

      All of which makes it possible, as Fine suggested, that the large legacy automakers will start investing more heavily in the charging business in the near future. Mercedes, he noted, just announced in January that it is entering into a partnership with charging firms ChargePoint and MN8 Energy to develop about 400 charging stations across North America by 2027. By necessity, others might have to follow suit if they want to protect their massive planned investments in the EV sector.

      “I’m not in the business of telling [automakers] what to do, but I do think they have a lot at risk,” Fine said. “They’re spending billions and billions of dollars to produce these cars, and I don’t think they can afford an epic failure [if] people don’t buy them because there’s no charging infrastructure. If they’re waiting for the startups to build out rapidly, then they may be waiting longer than they hope to wait.” More

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      in Energy

      Finding “hot spots” where compounding environmental and economic risks converge

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      A computational tool developed by researchers at the MIT Joint Program on the Science and Policy of Global Change pinpoints specific counties within the United States that are particularly vulnerable to economic distress resulting from a transition from fossil fuels to low-carbon energy sources. By combining county-level data on employment in fossil fuel (oil, natural gas, and coal) industries with data on populations below the poverty level, the tool identifies locations with high risks for transition-driven economic hardship. It turns out that many of these high-risk counties are in the south-central U.S., with a heavy concentration in the lower portions of the Mississippi River.

      The computational tool, which the researchers call the System for the Triage of Risks from Environmental and Socio-economic Stressors (STRESS) platform, almost instantly displays these risk combinations on an easy-to-read visual map, revealing those counties that stand to gain the most from targeted green jobs retraining programs.  

      Drawing on data that characterize land, water, and energy systems; biodiversity; demographics; environmental equity; and transportation networks, the STRESS platform enables users to assess multiple, co-evolving, compounding hazards within a U.S. geographical region from the national to the county level. Because of its comprehensiveness and precision, this screening-level visualization tool can pinpoint risk “hot spots” that can be subsequently investigated in greater detail. Decision-makers can then plan targeted interventions to boost resilience to location-specific physical and economic risks.

      The platform and its applications are highlighted in a new study in the journal Frontiers in Climate.

      “As risks to natural and managed resources — and to the economies that depend upon them — become more complex, interdependent, and compounding amid rapid environmental and societal changes, they require more and more human and computational resources to understand and act upon,” says MIT Joint Program Deputy Director C. Adam Schlosser, the lead author of the study. “The STRESS platform provides decision-makers with an efficient way to combine and analyze data on those risks that matter most to them, identify ‘hot spots’ of compounding risk, and design interventions to minimize that risk.”

      In one demonstration of the STRESS platform’s capabilities, the study shows that national and global actions to reduce greenhouse gas emissions could simultaneously reduce risks to land, water, and air quality in the upper Mississippi River basin while increasing economic risks in the lower basin, where poverty and unemployment are already disproportionate. In another demonstration, the platform finds concerning “hot spots” where flood risk, poverty, and nonwhite populations coincide.

      The risk triage platform is based on an emerging discipline called multi-sector dynamics (MSD), which seeks to understand and model compounding risks and potential tipping points across interconnected natural and human systems. Tipping points occur when these systems can no longer sustain multiple, co-evolving stresses, such as extreme events, population growth, land degradation, drinkable water shortages, air pollution, aging infrastructure, and increased human demands. MSD researchers use observations and computer models to identify key precursory indicators of such tipping points, providing decision-makers with critical information that can be applied to mitigate risks and boost resilience in natural and managed resources. With funding from the U.S. Department of Energy, the MIT Joint Program has since 2018 been developing MSD expertise and modeling tools and using them to explore compounding risks and potential tipping points in selected regions of the United States.

      Current STRESS platform data includes more than 100 risk metrics at the county-level scale, but data collection is ongoing. MIT Joint Program researchers are continuing to develop the STRESS platform as an “open-science tool” that welcomes input from academics, researchers, industry and the general public. More

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      in Energy

      Minimizing electric vehicles’ impact on the grid

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      National and global plans to combat climate change include increasing the electrification of vehicles and the percentage of electricity generated from renewable sources. But some projections show that these trends might require costly new power plants to meet peak loads in the evening when cars are plugged in after the workday. What’s more, overproduction of power from solar farms during the daytime can waste valuable electricity-generation capacity.

      In a new study, MIT researchers have found that it’s possible to mitigate or eliminate both these problems without the need for advanced technological systems of connected devices and real-time communications, which could add to costs and energy consumption. Instead, encouraging the placing of charging stations for electric vehicles (EVs) in strategic ways, rather than letting them spring up anywhere, and setting up systems to initiate car charging at delayed times could potentially make all the difference.

      The study, published today in the journal Cell Reports Physical Science, is by Zachary Needell PhD ’22, postdoc Wei Wei, and Professor Jessika Trancik of MIT’s Institute for Data, Systems, and Society.

      In their analysis, the researchers used data collected in two sample cities: New York and Dallas. The data were gathered from, among other sources, anonymized records collected via onboard devices in vehicles, and surveys that carefully sampled populations to cover variable travel behaviors. They showed the times of day cars are used and for how long, and how much time the vehicles spend at different kinds of locations — residential, workplace, shopping, entertainment, and so on.

      The findings, Trancik says, “round out the picture on the question of where to strategically locate chargers to support EV adoption and also support the power grid.”

      Better availability of charging stations at workplaces, for example, could help to soak up peak power being produced at midday from solar power installations, which might otherwise go to waste because it is not economical to build enough battery or other storage capacity to save all of it for later in the day. Thus, workplace chargers can provide a double benefit, helping to reduce the evening peak load from EV charging and also making use of the solar electricity output.

      These effects on the electric power system are considerable, especially if the system must meet charging demands for a fully electrified personal vehicle fleet alongside the peaks in other demand for electricity, for example on the hottest days of the year. If unmitigated, the evening peaks in EV charging demand could require installing upwards of 20 percent more power-generation capacity, the researchers say.

      “Slow workplace charging can be more preferable than faster charging technologies for enabling a higher utilization of midday solar resources,” Wei says.

      Meanwhile, with delayed home charging, each EV charger could be accompanied by a simple app to estimate the time to begin its charging cycle so that it charges just before it is needed the next day. Unlike other proposals that require a centralized control of the charging cycle, such a system needs no interdevice communication of information and can be preprogrammed — and can accomplish a major shift in the demand on the grid caused by increasing EV penetration. The reason it works so well, Trancik says, is because of the natural variability in driving behaviors across individuals in a population.

      By “home charging,” the researchers aren’t only referring to charging equipment in individual garages or parking areas. They say it’s essential to make charging stations available in on-street parking locations and in apartment building parking areas as well.

      Trancik says the findings highlight the value of combining the two measures — workplace charging and delayed home charging — to reduce peak electricity demand, store solar energy, and conveniently meet drivers’ charging needs on all days. As the team showed in earlier research, home charging can be a particularly effective component of a strategic package of charging locations; workplace charging, they have found, is not a good substitute for home charging for meeting drivers’ needs on all days.

      “Given that there’s a lot of public money going into expanding charging infrastructure,” Trancik says, “how do you incentivize the location such that this is going to be efficiently and effectively integrated into the power grid without requiring a lot of additional capacity expansion?” This research offers some guidance to policymakers on where to focus rules and incentives.

      “I think one of the fascinating things about these findings is that by being strategic you can avoid a lot of physical infrastructure that you would otherwise need,” she adds. “Your electric vehicles can displace some of the need for stationary energy storage, and you can also avoid the need to expand the capacity of power plants, by thinking about the location of chargers as a tool for managing demands — where they occur and when they occur.”

      Delayed home charging could make a surprising amount of difference, the team found. “It’s basically incentivizing people to begin charging later. This can be something that is preprogrammed into your chargers. You incentivize people to delay the onset of charging by a bit, so that not everyone is charging at the same time, and that smooths out the peak.”

      Such a program would require some advance commitment on the part of participants. “You would need to have enough people committing to this program in advance to avoid the investment in physical infrastructure,” Trancik says. “So, if you have enough people signing up, then you essentially don’t have to build those extra power plants.”

      It’s not a given that all of this would line up just right, and putting in place the right mix of incentives would be crucial. “If you want electric vehicles to act as an effective storage technology for solar energy, then the [EV] market needs to grow fast enough in order to be able to do that,” Trancik says.

      To best use public funds to help make that happen, she says, “you can incentivize charging installations, which would go through ideally a competitive process — in the private sector, you would have companies bidding for different projects, but you can incentivize installing charging at workplaces, for example, to tap into both of these benefits.” Chargers people can access when they are parked near their residences are also important, Trancik adds, but for other reasons. Home charging is one of the ways to meet charging needs while avoiding inconvenient disruptions to people’s travel activities.

      The study was supported by the European Regional Development Fund Operational Program for Competitiveness and Internationalization, the Lisbon Portugal Regional Operation Program, and the Portuguese Foundation for Science and Technology. More

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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