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      Study: Ice flow is more sensitive to stress than previously thought

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      The rate of glacier ice flow is more sensitive to stress than previously calculated, according to a new study by MIT researchers that upends a decades-old equation used to describe ice flow.

      Stress in this case refers to the forces acting on Antarctic glaciers, which are primarily influenced by gravity that drags the ice down toward lower elevations. Viscous glacier ice flows “really similarly to honey,” explains Joanna Millstein, a PhD student in the Glacier Dynamics and Remote Sensing Group and lead author of the study. “If you squeeze honey in the center of a piece of toast, and it piles up there before oozing outward, that’s the exact same motion that’s happening for ice.”

      The revision to the equation proposed by Millstein and her colleagues should improve models for making predictions about the ice flow of glaciers. This could help glaciologists predict how Antarctic ice flow might contribute to future sea level rise, although Millstein said the equation change is unlikely to raise estimates of sea level rise beyond the maximum levels already predicted under climate change models.

      “Almost all our uncertainties about sea level rise coming from Antarctica have to do with the physics of ice flow, though, so this will hopefully be a constraint on that uncertainty,” she says.

      Other authors on the paper, published in Nature Communications Earth and Environment, include Brent Minchew, the Cecil and Ida Green Career Development Professor in MIT’s Department of Earth, Atmospheric, and Planetary Sciences, and Samuel Pegler, a university academic fellow at the University of Leeds.

      Benefits of big data

      The equation in question, called Glen’s Flow Law, is the most widely used equation to describe viscous ice flow. It was developed in 1958 by British scientist J.W. Glen, one of the few glaciologists working on the physics of ice flow in the 1950s, according to Millstein.

      With relatively few scientists working in the field until recently, along with the remoteness and inaccessibility of most large glacier ice sheets, there were few attempts to calibrate Glen’s Flow Law outside the lab until recently. In the recent study, Millstein and her colleagues took advantage of a new wealth of satellite imagery over Antarctic ice shelves, the floating extensions of the continent’s ice sheet, to revise the stress exponent of the flow law.

      “In 2002, this major ice shelf [Larsen B] collapsed in Antarctica, and all we have from that collapse is two satellite images that are a month apart,” she says. “Now, over that same area we can get [imagery] every six days.”

      The new analysis shows that “the ice flow in the most dynamic, fastest-changing regions of Antarctica — the ice shelves, which basically hold back and hug the interior of the continental ice — is more sensitive to stress than commonly assumed,” Millstein says. She’s optimistic that the growing record of satellite data will help capture rapid changes on Antarctica in the future, providing insights into the underlying physical processes of glaciers.   

      But stress isn’t the only thing that affects ice flow, the researchers note. Other parts of the flow law equation represent differences in temperature, ice grain size and orientation, and impurities and water contained in the ice — all of which can alter flow velocity. Factors like temperature could be especially important in understanding how ice flow impacts sea level rise in the future, Millstein says.

      Cracking under strain

      Millstein and colleagues are also studying the mechanics of ice sheet collapse, which involves different physical models than those used to understand the ice flow problem. “The cracking and breaking of ice is what we’re working on now, using strain rate observations,” Millstein says.

      The researchers use InSAR, radar images of the Earth’s surface collected by satellites, to observe deformations of the ice sheets that can be used to make precise measurements of strain. By observing areas of ice with high strain rates, they hope to better understand the rate at which crevasses and rifts propagate to trigger collapse.

      The research was supported by the National Science Foundation. More

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      Using nature’s structures in wooden buildings

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      Concern about climate change has focused significant attention on the buildings sector, in particular on the extraction and processing of construction materials. The concrete and steel industries together are responsible for as much as 15 percent of global carbon dioxide emissions. In contrast, wood provides a natural form of carbon sequestration, so there’s a move to use timber instead. Indeed, some countries are calling for public buildings to be made at least partly from timber, and large-scale timber buildings have been appearing around the world.

      Observing those trends, Caitlin Mueller ’07, SM ’14, PhD ’14, an associate professor of architecture and of civil and environmental engineering in the Building Technology Program at MIT, sees an opportunity for further sustainability gains. As the timber industry seeks to produce wooden replacements for traditional concrete and steel elements, the focus is on harvesting the straight sections of trees. Irregular sections such as knots and forks are turned into pellets and burned, or ground up to make garden mulch, which will decompose within a few years; both approaches release the carbon trapped in the wood to the atmosphere.

      For the past four years, Mueller and her Digital Structures research group have been developing a strategy for “upcycling” those waste materials by using them in construction — not as cladding or finishes aimed at improving appearance, but as structural components. “The greatest value you can give to a material is to give it a load-bearing role in a structure,” she says. But when builders use virgin materials, those structural components are the most emissions-intensive parts of buildings due to their large volume of high-strength materials. Using upcycled materials in place of those high-carbon systems is therefore especially impactful in reducing emissions.

      Mueller and her team focus on tree forks — that is, spots where the trunk or branch of a tree divides in two, forming a Y-shaped piece. In architectural drawings, there are many similar Y-shaped nodes where straight elements come together. In such cases, those units must be strong enough to support critical loads.

      “Tree forks are naturally engineered structural connections that work as cantilevers in trees, which means that they have the potential to transfer force very efficiently thanks to their internal fiber structure,” says Mueller. “If you take a tree fork and slice it down the middle, you see an unbelievable network of fibers that are intertwining to create these often three-dimensional load transfer points in a tree. We’re starting to do the same thing using 3D printing, but we’re nowhere near what nature does in terms of complex fiber orientation and geometry.”

      She and her team have developed a five-step “design-to-fabrication workflow” that combines natural structures such as tree forks with the digital and computational tools now used in architectural design. While there’s long been a “craft” movement to use natural wood in railings and decorative features, the use of computational tools makes it possible to use wood in structural roles — without excessive cutting, which is costly and may compromise the natural geometry and internal grain structure of the wood.

      Given the wide use of digital tools by today’s architects, Mueller believes that her approach is “at least potentially scalable and potentially achievable within our industrialized materials processing systems.” In addition, by combining tree forks with digital design tools, the novel approach can also support the trend among architects to explore new forms. “Many iconic buildings built in the past two decades have unexpected shapes,” says Mueller. “Tree branches have a very specific geometry that sometimes lends itself to an irregular or nonstandard architectural form — driven not by some arbitrary algorithm but by the material itself.”

      Step 0: Find a source, set goals

      Before starting their design-to-fabrication process, the researchers needed to locate a source of tree forks. Mueller found help in the Urban Forestry Division of the City of Somerville, Massachusetts, which maintains a digital inventory of more than 2,000 street trees — including more than 20 species — and records information about the location, approximate trunk diameter, and condition of each tree.

      With permission from the forestry division, the team was on hand in 2018 when a large group of trees was cut down near the site of the new Somerville High School. Among the heavy equipment on site was a chipper, poised to turn all the waste wood into mulch. Instead, the workers obligingly put the waste wood into the researchers’ truck to be brought to MIT.

      In their project, the MIT team sought not only to upcycle that waste material but also to use it to create a structure that would be valued by the public. “Where I live, the city has had to take down a lot of trees due to damage from an invasive species of beetle,” Mueller explains. “People get really upset — understandably. Trees are an important part of the urban fabric, providing shade and beauty.” She and her team hoped to reduce that animosity by “reinstalling the removed trees in the form of a new functional structure that would recreate the atmosphere and spatial experience previously provided by the felled trees.”

      With their source and goals identified, the researchers were ready to demonstrate the five steps in their design-to-fabrication workflow for making spatial structures using an inventory of tree forks.

      Step 1: Create a digital material library

      The first task was to turn their collection of tree forks into a digital library. They began by cutting off excess material to produce isolated tree forks. They then created a 3D scan of each fork. Mueller notes that as a result of recent progress in photogrammetry (measuring objects using photographs) and 3D scanning, they could create high-resolution digital representations of the individual tree forks with relatively inexpensive equipment, even using apps that run on a typical smartphone.

      In the digital library, each fork is represented by a “skeletonized” version showing three straight bars coming together at a point. The relative geometry and orientation of the branches are of particular interest because they determine the internal fiber orientation that gives the component its strength.

      Step 2: Find the best match between the initial design and the material library

      Like a tree, a typical architectural design is filled with Y-shaped nodes where three straight elements meet up to support a critical load. The goal was therefore to match the tree forks in the material library with the nodes in a sample architectural design.

      First, the researchers developed a “mismatch metric” for quantifying how well the geometries of a particular tree fork aligned with a given design node. “We’re trying to line up the straight elements in the structure with where the branches originally were in the tree,” explains Mueller. “That gives us the optimal orientation for load transfer and maximizes use of the inherent strength of the wood fiber.” The poorer the alignment, the higher the mismatch metric.

      The goal was to get the best overall distribution of all the tree forks among the nodes in the target design. Therefore, the researchers needed to try different fork-to-node distributions and, for each distribution, add up the individual fork-to-node mismatch errors to generate an overall, or global, matching score. The distribution with the best matching score would produce the most structurally efficient use of the total tree fork inventory.

      Since performing that process manually would take far too long to be practical, they turned to the “Hungarian algorithm,” a technique developed in 1955 for solving such problems. “The brilliance of the algorithm is solving that [matching] problem very quickly,” Mueller says. She notes that it’s a very general-use algorithm. “It’s used for things like marriage match-making. It can be used any time you have two collections of things that you’re trying to find unique matches between. So, we definitely didn’t invent the algorithm, but we were the first to identify that it could be used for this problem.”

      The researchers performed repeated tests to show possible distributions of the tree forks in their inventory and found that the matching score improved as the number of forks available in the material library increased — up to a point. In general, the researchers concluded that the mismatch score was lowest, and thus best, when there were about three times as many forks in the material library as there were nodes in the target design.

      Step 3: Balance designer intention with structural performance

      The next step in the process was to incorporate the intention or preference of the designer. To permit that flexibility, each design includes a limited number of critical parameters, such as bar length and bending strain. Using those parameters, the designer can manually change the overall shape, or geometry, of the design or can use an algorithm that automatically changes, or “morphs,” the geometry. And every time the design geometry changes, the Hungarian algorithm recalculates the optimal fork-to-node matching.

      “Because the Hungarian algorithm is extremely fast, all the morphing and the design updating can be really fluid,” notes Mueller. In addition, any change to a new geometry is followed by a structural analysis that checks the deflections, strain energy, and other performance measures of the structure. On occasion, the automatically generated design that yields the best matching score may deviate far from the designer’s initial intention. In such cases, an alternative solution can be found that satisfactorily balances the design intention with a low matching score.

      Step 4: Automatically generate the machine code for fast cutting

      When the structural geometry and distribution of tree forks have been finalized, it’s time to think about actually building the structure. To simplify assembly and maintenance, the researchers prepare the tree forks by recutting their end faces to better match adjoining straight timbers and cutting off any remaining bark to reduce susceptibility to rot and fire.

      To guide that process, they developed a custom algorithm that automatically computes the cuts needed to make a given tree fork fit into its assigned node and to strip off the bark. The goal is to remove as little material as possible but also to avoid a complex, time-consuming machining process. “If we make too few cuts, we’ll cut off too much of the critical structural material. But we don’t want to make a million tiny cuts because it will take forever,” Mueller explains.

      The team uses facilities at the Autodesk Boston Technology Center Build Space, where the robots are far larger than any at MIT and the processing is all automated. To prepare each tree fork, they mount it on a robotic arm that pushes the joint through a traditional band saw in different orientations, guided by computer-generated instructions. The robot also mills all the holes for the structural connections. “That’s helpful because it ensures that everything is aligned the way you expect it to be,” says Mueller.

      Step 5: Assemble the available forks and linear elements to build the structure

      The final step is to assemble the structure. The tree-fork-based joints are all irregular, and combining them with the precut, straight wooden elements could be difficult. However, they’re all labeled. “All the information for the geometry is embedded in the joint, so the assembly process is really low-tech,” says Mueller. “It’s like a child’s toy set. You just follow the instructions on the joints to put all the pieces together.”

      They installed their final structure temporarily on the MIT campus, but Mueller notes that it was only a portion of the structure they plan to eventually build. “It had 12 nodes that we designed and fabricated using our process,” she says, adding that the team’s work was “a little interrupted by the pandemic.” As activity on campus resumes, the researchers plan to finish designing and building the complete structure, which will include about 40 nodes and will be installed as an outdoor pavilion on the site of the felled trees in Somerville.

      In addition, they will continue their research. Plans include working with larger material libraries, some with multibranch forks, and replacing their 3D-scanning technique with computerized tomography scanning technologies that can automatically generate a detailed geometric representation of a tree fork, including its precise fiber orientation and density. And in a parallel project, they’ve been exploring using their process with other sources of materials, with one case study focusing on using material from a demolished wood-framed house to construct more than a dozen geodesic domes.

      To Mueller, the work to date already provides new guidance for the architectural design process. With digital tools, it has become easy for architects to analyze the embodied carbon or future energy use of a design option. “Now we have a new metric of performance: How well am I using available resources?” she says. “With the Hungarian algorithm, we can compute that metric basically in real time, so we can work rapidly and creatively with that as another input to the design process.”

      This research was supported by MIT’s School of Architecture and Planning via the HASS Award.

      This article appears in the Autumn 2021 issue of Energy Futures, the magazine of the MIT Energy Initiative. More

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      New maps show airplane contrails over the U.S. dropped steeply in 2020

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      As Covid-19’s initial wave crested around the world, travel restrictions and a drop in passengers led to a record number of grounded flights in 2020. The air travel reduction cleared the skies of not just jets but also the fluffy white contrails they produce high in the atmosphere.

      MIT engineers have mapped the contrails that were generated over the United States in 2020, and compared the results to prepandemic years. They found that on any given day in 2018, and again in 2019, contrails covered a total area equal to Massachusetts and Connecticut combined. In 2020, this contrail coverage shrank by about 20 percent, mirroring a similar drop in U.S. flights.  

      While 2020’s contrail dip may not be surprising, the findings are proof that the team’s mapping technique works. Their study marks the first time researchers have captured the fine and ephemeral details of contrails over a large continental scale.

      Now, the researchers are applying the technique to predict where in the atmosphere contrails are likely to form. The cloud-like formations are known to play a significant role in aviation-related global warming. The team is working with major airlines to forecast regions in the atmosphere where contrails may form, and to reroute planes around these regions to minimize contrail production.

      “This kind of technology can help divert planes to prevent contrails, in real time,” says Steven Barrett, professor and associate head of MIT’s Department of Aeronautics and Astronautics. “There’s an unusual opportunity to halve aviation’s climate impact by eliminating most of the contrails produced today.”

      Barrett and his colleagues have published their results today in the journal Environmental Research Letters. His co-authors at MIT include graduate student Vincent Meijer, former graduate student Luke Kulik, research scientists Sebastian Eastham, Florian Allroggen, and Raymond Speth, and LIDS Director and professor Sertac Karaman.

      Trail training

      About half of the aviation industry’s contribution to global warming comes directly from planes’ carbon dioxide emissions. The other half is thought to be a consequence of their contrails. The signature white tails are produced when a plane’s hot, humid exhaust mixes with cool humid air high in the atmosphere. Emitted in thin lines, contrails quickly spread out and can act as blankets that trap the Earth’s outgoing heat.

      While a single contrail may not have much of a warming effect, taken together contrails have a significant impact. But the estimates of this effect are uncertain and based on computer modeling as well as limited satellite data. What’s more, traditional computer vision algorithms that analyze contrail data have a hard time discerning the wispy tails from natural clouds.

      To precisely pick out and track contrails over a large scale, the MIT team looked to images taken by NASA’s GOES-16, a geostationary satellite that hovers over the same swath of the Earth, including the United States, taking continuous, high-resolution images.

      The team first obtained about 100 images taken by the satellite, and trained a set of people to interpret remote sensing data and label each image’s pixel as either part of a contrail or not. They used this labeled dataset to train a computer-vision algorithm to discern a contrail from a cloud or other image feature.

      The researchers then ran the algorithm on about 100,000 satellite images, amounting to nearly 6 trillion pixels, each pixel representing an area of about 2 square kilometers. The images covered the contiguous U.S., along with parts of Canada and Mexico, and were taken about every 15 minutes, between Jan. 1, 2018, and Dec. 31, 2020.

      The algorithm automatically classified each pixel as either a contrail or not a contrail, and generated daily maps of contrails over the United States. These maps mirrored the major flight paths of most U.S. airlines, with some notable differences. For instance, contrail “holes” appeared around major airports, which reflects the fact that planes landing and taking off around airports are generally not high enough in the atmosphere for contrails to form.

      “The algorithm knows nothing about where planes fly, and yet when processing the satellite imagery, it resulted in recognizable flight routes,” Barrett says. “That’s one piece of evidence that says this method really does capture contrails over a large scale.”

      Cloudy patterns

      Based on the algorithm’s maps, the researchers calculated the total area covered each day by contrails in the US. On an average day in 2018 and in 2019, U.S. contrails took up about 43,000 square kilometers. This coverage dropped by 20 percent in March of 2020 as the pandemic set in. From then on, contrails slowly reappeared as air travel resumed through the year.

      The team also observed daily and seasonal patterns. In general, contrails appeared to peak in the morning and decline in the afternoon. This may be a training artifact: As natural cirrus clouds are more likely to form in the afternoon, the algorithm may have trouble discerning contrails amid the clouds later in the day. But it might also be an important indication about when contrails form most. Contrails also peaked in late winter and early spring, when more of the air is naturally colder and more conducive for contrail formation.

      The team has now adapted the technique to predict where contrails are likely to form in real time. Avoiding these regions, Barrett says, could take a significant, almost immediate chunk out of aviation’s global warming contribution.  

      “Most measures to make aviation sustainable take a long time,” Barrett says. “(Contrail avoidance) could be accomplished in a few years, because it requires small changes to how aircraft are flown, with existing airplanes and observational technology. It’s a near-term way of reducing aviation’s warming by about half.”

      The team is now working towards this objective of large-scale contrail avoidance using realtime satellite observations.

      This research was supported in part by NASA and the MIT Environmental Solutions Initiative. More

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      Study reveals chemical link between wildfire smoke and ozone depletion

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      The Australian wildfires in 2019 and 2020 were historic for how far and fast they spread, and for how long and powerfully they burned. All told, the devastating “Black Summer” fires blazed across more than 43 million acres of land, and extinguished or displaced nearly 3 billion animals. The fires also injected over 1 million tons of smoke particles into the atmosphere, reaching up to 35 kilometers above Earth’s surface — a mass and reach comparable to that of an erupting volcano.

      Now, atmospheric chemists at MIT have found that the smoke from those fires set off chemical reactions in the stratosphere that contributed to the destruction of ozone, which shields the Earth from incoming ultraviolet radiation. The team’s study, appearing this week in the Proceedings of the National Academy of Sciences, is the first to establish a chemical link between wildfire smoke and ozone depletion.

      In March 2020, shortly after the fires subsided, the team observed a sharp drop in nitrogen dioxide in the stratosphere, which is the first step in a chemical cascade that is known to end in ozone depletion. The researchers found that this drop in nitrogen dioxide directly correlates with the amount of smoke that the fires released into the stratosphere. They estimate that this smoke-induced chemistry depleted the column of ozone by 1 percent.

      To put this in context, they note that the phaseout of ozone-depleting gases under a worldwide agreement to stop their production has led to about a 1 percent ozone recovery from earlier ozone decreases over the past 10 years — meaning that the wildfires canceled those hard-won diplomatic gains for a short period. If future wildfires grow stronger and more frequent, as they are predicted to do with climate change, ozone’s projected recovery could be delayed by years. 

      “The Australian fires look like the biggest event so far, but as the world continues to warm, there is every reason to think these fires will become more frequent and more intense,” says lead author Susan Solomon, the Lee and Geraldine Martin Professor of Environmental Studies at MIT. “It’s another wakeup call, just as the Antarctic ozone hole was, in the sense of showing how bad things could actually be.”

      The study’s co-authors include Kane Stone, a research scientist in MIT’s Department of Earth, Atmospheric, and Planetary Sciences, along with collaborators at multiple institutions including the University of Saskatchewan, Jinan University, the National Center for Atmospheric Research, and the University of Colorado at Boulder.

      Chemical trace

      Massive wildfires are known to generate pyrocumulonimbus — towering clouds of smoke that can reach into the stratosphere, the layer of the atmosphere that lies between about 15 and 50 kilometers above the Earth’s surface. The smoke from Australia’s wildfires reached well into the stratosphere, as high as 35 kilometers.

      In 2021, Solomon’s co-author, Pengfei Yu at Jinan University, carried out a separate study of the fires’ impacts and found that the accumulated smoke warmed parts of the stratosphere by as much as 2 degrees Celsius — a warming that persisted for six months. The study also found hints of ozone destruction in the Southern Hemisphere following the fires.

      Solomon wondered whether smoke from the fires could have depleted ozone through a chemistry similar to volcanic aerosols. Major volcanic eruptions can also reach into the stratosphere, and in 1989, Solomon discovered that the particles in these eruptions can destroy ozone through a series of chemical reactions. As the particles form in the atmosphere, they gather moisture on their surfaces. Once wet, the particles can react with circulating chemicals in the stratosphere, including dinitrogen pentoxide, which reacts with the particles to form nitric acid.

      Normally, dinitrogen pentoxide reacts with the sun to form various nitrogen species, including nitrogen dioxide, a compound that binds with chlorine-containing chemicals in the stratosphere. When volcanic smoke converts dinitrogen pentoxide into nitric acid, nitrogen dioxide drops, and the chlorine compounds take another path, morphing into chlorine monoxide, the main human-made agent that destroys ozone.

      “This chemistry, once you get past that point, is well-established,” Solomon says. “Once you have less nitrogen dioxide, you have to have more chlorine monoxide, and that will deplete ozone.”

      Cloud injection

      In the new study, Solomon and her colleagues looked at how concentrations of nitrogen dioxide in the stratosphere changed following the Australian fires. If these concentrations dropped significantly, it would signal that wildfire smoke depletes ozone through the same chemical reactions as some volcanic eruptions.

      The team looked to observations of nitrogen dioxide taken by three independent satellites that have surveyed the Southern Hemisphere for varying lengths of time. They compared each satellite’s record in the months and years leading up to and following the Australian fires. All three records showed a significant drop in nitrogen dioxide in March 2020. For one satellite’s record, the drop represented a record low among observations spanning the last 20 years.

      To check that the nitrogen dioxide decrease was a direct chemical effect of the fires’ smoke, the researchers carried out atmospheric simulations using a global, three-dimensional model that simulates hundreds of chemical reactions in the atmosphere, from the surface on up through the stratosphere.

      The team injected a cloud of smoke particles into the model, simulating what was observed from the Australian wildfires. They assumed that the particles, like volcanic aerosols, gathered moisture. They then ran the model multiple times and compared the results to simulations without the smoke cloud.

      In every simulation incorporating wildfire smoke, the team found that as the amount of smoke particles increased in the stratosphere, concentrations of nitrogen dioxide decreased, matching the observations of the three satellites.

      “The behavior we saw, of more and more aerosols, and less and less nitrogen dioxide, in both the model and the data, is a fantastic fingerprint,” Solomon says. “It’s the first time that science has established a chemical mechanism linking wildfire smoke to ozone depletion. It may only be one chemical mechanism among several, but it’s clearly there. It tells us these particles are wet and they had to have caused some ozone depletion.”

      She and her collaborators are looking into other reactions triggered by wildfire smoke that might further contribute to stripping ozone. For the time being, the major driver of ozone depletion remains chlorofluorocarbons, or CFCs — chemicals such as old refrigerants that have been banned under the Montreal Protocol, though they continue to linger in the stratosphere. But as global warming leads to stronger, more frequent wildfires, their smoke could have a serious, lasting impact on ozone.

      “Wildfire smoke is a toxic brew of organic compounds that are complex beasts,” Solomon says. “And I’m afraid ozone is getting pummeled by a whole series of reactions that we are now furiously working to unravel.”

      This research was supported in part by the National Science Foundation and NASA. More

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      Progress toward a sustainable campus food system

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      As part of MIT’s updated climate action plan, known as “Fast Forward,” Institute leadership committed to establishing a set of quantitative goals in 2022 related to food, water, and waste systems that advance MIT’s commitment to climate. Moving beyond the impact of campus energy systems, these newly proposed goals take a holistic view of the drivers of climate change and set the stage for new frontiers of collaborative climate work. “With the release of ‘Fast Forward,’ the MIT Office of Sustainability is setting out to partner with campus groups to study and quantify the climate impact of our campus food, while deeply considering the social, cultural, economic, and health aspects of a sustainable food system,” explains Susy Jones, senior sustainability project manager. 

      While “Fast Forward” is MIT’s first climate action plan to integrate the campus food system, the Division of Student Life (DSL) has long worked with dining vendors, MIT’s Office of Sustainability (MITOS), and other campus partners to advance a more sustainable, affordable, and equitable food system. Initiatives have ranged from increasing access to low-cost groceries on and around campus to sourcing sustainable coffee for campus cafes.

      Even with the complexities of operating during the pandemic, efforts in this area accelerated with the launch of new partnerships, support for local food industries, and even a food-startup incubator in the Stratton Student Center (Building W20). “Despite challenges posed by the pandemic, MIT Dining has been focused on positive change — driven in part by student input, alterations to the food landscape, and our ongoing goal to support a more sustainable and equitable campus food system,” says Mark Hayes, director of MIT Dining.

      New vendors on campus focus on healthy food systems

      For many, a fresh cup of coffee is a daily ritual. At MIT, that cup of coffee also offers an opportunity to make a more sustainable choice at the Forbes Family Café in the Stata Center (Building 32). The cafe now brews coffee by Dean’s Beans, a local roaster whose mission is to “prove that a for-profit business could create meaningful change through ethical business practices rooted in respect for the earth, the farmer, our co-workers, and the consumer.” The choice of Dean’s Beans — a certified B Corporation located in Orange, Massachusetts — as the new vendor in this space helps advance MIT’s commitment to sustainability. Businesses that achieve this certification meet rigorous social and environmental goals. “With choices like this, we’re taking big issues down to the campus level,” says Hayes. Dean’s Beans focuses on long-term producer relationships, organic shade-grown and bird-friendly coffee, a solar-powered roasting facility, and people-centered development programs. These practices contribute to healthier environments and habitats — benefiting farmers, soils, birds, pollinators, and more.

      Another innovative new food concept for the MIT community can be found down the street in the Stratton Student Center. The Launchpad, a nonprofit food business incubator created in partnership with CommonWealth Kitchen (CWK), debuted this fall in the second-floor Lobdell Food Court. It offers the MIT community more variety and healthy food options while also “advancing CWK’s and MIT’s mutual goal to support diverse, local start-up food businesses and to create a more just, equitable, and sustainable food economy,” according to DSL. Work on the Launchpad began in 2018, bringing together the Student Center Dining Concepts Working Group, comprising students from the Undergraduate Association, Graduate Student Council, DormCon, house dining chairs, and other students interested in dining and dining staff from the MITOS and DSL. Their goal was to re-envision dining options available in Lobdell to support local, diverse, and sustainable menus. “We’ve been nurturing a partnership with CommonWealth Kitchen for years and are excited to partner with them on a project that re-imagines the relationship between campus and local food systems,” says Jones. “And, of course, the vegetarian arepas are a highlight,” she adds.

      Local partnerships for sustainability

      The impacts of Covid-19 on local food businesses quickly came into focus in early 2020. For the New England fishing industry, this impact was acute — with restaurant closures, event cancellations, and disruptions in the global supply chain, fisheries suddenly found a dearth of markets for their catch, undermining their source of income. One way to address this confluence of challenges was for fisheries to expand into new markets where they may have had limited knowledge or experience.

      Enter MIT Sea Grant and MIT Dining. Supported in part by funding from the National Oceanic and Atmospheric Administration, MIT Sea Grant created the Covid-19 Rapid Response Program to develop new markets for local fisheries, including local food banks and direct sales to organizations including MIT. Though MIT Dining was stretched thin by the pandemic, the partnership offered a singular opportunity to support vital regional businesses and enhance menus in campus dining venues. “The stress level was unimaginable as more people were testing positive in the early days of the pandemic — it was the worst and most stressful time to do anything outside of what was completely necessary, and I get this phone call about chowder,” recalls Hayes. “Everyone is wearing two masks and standing six feet apart, but in about 15 seconds, I said to myself, ‘This is the exact time this needs to happen — in the middle of a pandemic when fishermen need support, families need support, people need support.’”

      Shortly after getting the call, Hayes and MIT Dining hosted a tasting event featuring “Small Boats, Big Taste Haddock Chowder,” developed through MIT Sea Grant’s work with the Cape Cod Commercial Fishermen’s Alliance, which helped independent fishermen stay on the water during Covid-19. The tasting event also offered students a break to stop by and sample the chowder, which later debuted and continues to be served at MIT dining halls. For Hayes, one success of the partnership was the agility it demonstrated. “We don’t know what the next crisis is going to be, but these experiences will make us stronger to handle the next moment when people need the food system to work,” he says.

      In addition to ready-made options for students, MIT Dining and partners have also been working to support students who prepare their own meals, collaborating with local businesses to provide students access to lower-cost and at-cost groceries and food products. The Food Security Action Team, convened by Senior Associate Dean for Student Support and Well-being David Randall and DSL Executive Director for Administration Peter Cummings, is focused on taking action, tracking, and updating the community on food security efforts. These efforts have included collaborating with the Daily Table, a new nonprofit community grocer in Central Square. The store now accepts TechCASH and recently worked with the committee to host an interactive food tour for students.

      Because food systems are so interdependent and partnerships are critical — on and off campus — Hayes says it’s important to continue to share and learn. “Sharing our stories is crucial because we can help strengthen networks of campuses, institutions, and businesses in New England to grow more sustainable food programs like these.” More

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      MIT entrepreneurs think globally, act locally

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      Born and raised amid the natural beauty of the Dominican Republic, Andrés Bisonó León feels a deep motivation to help solve a problem that has been threatening the Caribbean island nation’s tourism industry, its economy, and its people.

      As Bisonó León discussed with his long-time friend and mentor, the Walter M. May and A. Hazel May Professor of Mechanical Engineering (MechE) Alexander Slocum Sr., ugly mats of toxic sargassum seaweed have been encroaching on the Dominican Republic’s pristine beaches and other beaches in the Caribbean region, and public and private organizations have fought a losing battle using expensive, environmentally damaging methods to clean it up. Slocum, who was on the U.S. Department of Energy’s Deepwater Horizon team, has extensive experience with systems that operate in the ocean.

      “In the last 10 years,” says Bisonó León, now an MBA candidate in the MIT Sloan School of Management, “sargassum, a toxic seaweed invasion, has cost the Caribbean as much as $120 million a year in cleanup and has meant a 30 to 35 percent tourism reduction, affecting not only the tourism industry, but also the environment, marine life, local economies, and human health.”

      One of Bisonó León’s discussions with Slocum took place within earshot of MechE alumnus Luke Gray ’18, SM ’20, who had worked with Slocum on other projects and was at the time was about to begin his master’s program.

      “Professor Slocum and Andrés happened to be discussing the sargassum problem in Andrés’ home country,” Gray says. “A week later I was on a plane to the DR to collect sargassum samples and survey the problem in Punta Cana. When I returned, my master’s program was underway, and I already had my thesis project!”

      Gray also had started a working partnership with Bisonó León, which both say proceeded seamlessly right from the first moment.

      “I feel that Luke right away understood the magnitude of the problem and the value we could create in the Dominican Republic and across the Caribbean by teaming up,” Bisonó León says.

      Both Bisonó León and Gray also say they felt a responsibility to work toward helping the global environment.

      “All of my major projects up until now have involved machines for climate restoration and/or adaptation,” says Gray.

      The technologies Bisonó León and Gray arrived at after 18 months of R&D were designed to provide solutions both locally and globally.

      Their Littoral Collection Module (LCM) skims sargassum seaweed off the surface of the water with nets that can be mounted on any boat. The device sits across the boat, with two large hoops holding the nets open, one on each side. As the boat travels forward, it cuts through the seaweed, which flows to the sides of the vessel and through the hoops into the nets. Effective at sweeping the seaweed from the water, the device can be employed by anyone with a boat, including local fishermen whose livelihoods have been disrupted by the seaweed’s damaging effect on tourism and the local economy.

      The sargassum can then be towed out to sea, where Bisonó León’s and Gray’s second technology can come into play. By pumping the seaweed into very deep water, where it then sinks to the bottom of the ocean, the carbon in the seaweed can be sequestered. Other methods for disposing of the seaweed generally involve putting it into landfills, where it emits greenhouse gases such as methane and carbon dioxide as it breaks down. Although some seaweed can be put to other uses, including as fertilizer, sargassum has been found to contain hard-to-remove toxic substances such as arsenic and heavy metals.

      In spring 2020, Bisonó León and Gray formed a company, SOS (Sargassum Ocean Sequestration) Carbon.

      Bisonó León says he comes from a long line of entrepreneurs who often expressed much commitment to social impact. His family has been involved in several different industries, his grandfather and great uncles having opened the first cigar factory in the Dominican Republic in 1903.

      Gray says internships with startup companies and the undergraduate projects he did with Slocum developed his interest in entrepreneurship, and his involvement with the sargassum problem only reinforced that inclination. During his master’s program, he says he became “obsessed” with finding a solution.

      “Professor Slocum let me think extremely big, and so it was almost inevitable that the distillation of our two years of work would continue in some form, and starting a company happened to be the right path. My master’s experience of taking an essentially untouched problem like sargassum and then one year later designing, building, and sending 15,000 pounds of custom equipment to test for three months on a Dominican Navy ship made me realize I had discovered a recipe I could repeat — and machine design had become my core competency,” Gray says.

      During the initial research and development of their technologies, Bisonó León and Gray raised $258,000 from 20 different organizations. Between June and December 2021, they succeeded in removing 3.5 million pounds of sargassum and secured contracts with Grupo Puntacana, which operates several tourist resorts, and with other hotels such as Club Med in Punta Cana. The company subcontracts with the association of fishermen in Punta Cana, employing 15 fishermen who operate LCMs and training 35 others to join as the operation expands.

      Their success so far demonstrates “’mens et manus’ at work,” says Slocum, referring to MIT’s motto, which is Latin for “mind and hand.” “Geeks hear about a very real problem that affects very real people who have no other option for their livelihoods, and they respond by inventing a solution so elegant that it can be readily deployed by those most hurt by the problem to address the problem.

      “The team was always focused on the numbers, from physics to finance, and did not let hype or doubts deter their determination to rationally solve this huge problem.”

      Slocum says he could predict Bisonó León and Gray would work well together “because they started out as good, smart people with complementary skills whose hearts and minds were in the right place.”

      “We are working on having a global impact to reduce millions of tons of CO2 per year,” says Bisonó León. “With training from Sloan and cross-disciplinary collaborative spirit, we will be able to further expand environmental and social impact platforms much needed in the Caribbean to be able to drive real change regionally and globally.”

      “I hope SOS Carbon can serve as a model and inspire similar entrepreneurial efforts,” Gray says. More

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      in Energy

      Nurturing human communities and natural ecosystems

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      When she was in 7th grade, Heidi Li and the five other members of the Oyster Gardening Club cultivated hundreds of oysters to help repopulate the Chesapeake Bay. On the day they released the oysters into the bay, the event attracted TV journalists and local officials, including the governor. The attention opened the young Li’s eyes to the ways that a seemingly small effort in her local community could have a real-world impact.

      “I got to see firsthand how we can make change at a grassroots level and how that impacts where we are,” she says.

      Growing up in Howard County, Maryland, Li was constantly surrounded by nature. Her family made frequent trips to the Chesapeake Bay, as it reminded them of her parent’s home in Shandong, China. Li worked to bridge the cultural gap between parents, who grew up in China, and their children, who grew up in the U.S., and attended Chinese school every Sunday for 12 years. These experiences instilled in her a community-oriented mindset, which Li brought with her to MIT, where she now majors in materials science and engineering.

      During her first year, Li pursued a microbiology research project through the Undergraduate Research Opportunities Program (UROP) in the Department of Civil and Environmental Engineering. She studied microbes in aquatic environments, analyzing how the cleanliness of water impacted immunity and behavioral changes of the marine bacteria.

      The experience led her to consider the ways environmental policy affected sustainability efforts. She began applying the problem to energy, asking herself questions such as, “How can you take this specific economic principle and apply it to energy? What has energy policy looked like in the past and how can we tailor that to apply to our current energy system?”

      To explore the intersection of policy and energy, Li participated in the Roosevelt Project, through the Center of Energy and Environmental Policy Research, during the summer after her junior year. The project used case studies targeting specific communities in vulnerable areas to propose methods for a more sustainable future. Li focused on Pittsburgh, Pennsylvania, evaluating the efficiency of an energy transition from natural gas and fossil fuels to carbon-capture, which would mean redistributing the carbon dioxide produced by the coal industry. After traveling to Pittsburgh and interviewing stakeholders in the area, Li watched as local community leaders created physical places for citizens to share their ideas and opinions on the energy transition

      “I watched community leaders create a safe space for people from the surrounding town to share their ideas for entrepreneurship. I saw how important community is and how to create change at a grassroots level,” she says.

      In the summer of 2021, Li pursued an internship through the energy consulting firm Wood Mackenzie, where she looked at technologies that could potentially help with the energy transition from fossil fuels to renewable energy. Her job was to make sure the technology could be implemented efficiently and cost-effectively, optimizing the resources available to the surrounding area. The project allowed Li to engage with industry-based efforts to chart and analyze the technological advancements for various decarbonization scenarios. She hopes to continue looking at both the local, community-based, and external, industry-based, inputs on how economic policy would affect stakeholders.

      On campus, Li is the current president of the Sustainable Energy Alliance (SEA), where she aims to make students more conscious about climate change and their impact on the environment. During summer of her sophomore year, Li chaired a sustainability hackathon for over 200 high school students, where she designed and led the “Protecting Climate Refugees” and “Tackling Environmental Injustice” challenges to inspire students to think about humanitarian efforts for protecting frontline communities.

      “The whole goal of this is to empower students to think about solutions for themselves. Empowering students is really important to show them they can make change and inspire hope in themselves and the people around them,” she says.

      Li also hosted and produced “Open SEAcrets,” a podcast designed to engage MIT students with topics surrounding energy sustainability and provide them with the opportunity to share their opinions on the subject. She sees the podcast as a platform to raise awareness about energy, climate change, and environmental policy, while also inspiring a sense of community with listeners.

      When she is not in the classroom or the lab, Li relaxes by playing volleyball. She joined the Volleyball Club during her first year at MIT, though she has been playing since she was 12. The sport allows her to not only relieve stress, but also have conversations with both undergrads and graduate students, who bring different their backgrounds, interests, and experiences to conversations. The sport has also taught Li about teamwork, trust, and the importance of community in ways that her other experience doesn’t.

      Looking ahead, Li is currently working on a UROP project, called Climate Action Through Education (CATE), that designs climate change curriculum for K-12 grades and aims to show how climate change and energy are integral to peoples’ daily lives. Seeing the energy transition as an interdisciplinary problem, she wants to educate students about the problems of climate change and sustainability using perspectives from math, science, history, and psychology to name a few areas.

      But above all, Li wants to empower younger generations to develop solution-minded approaches to environmentalism. She hopes to give local communities a voice in policy implementation, with the end goal of a more sustainable future for all.

      “Finding a community you really thrive in will allow you to push yourself and be the best version of yourself you can be. I want to take this mindset and create spaces for people and establish and instill this sense of community,” she says. More

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      in Environment

      Reducing methane emissions at landfills

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      The second-largest driver of global warming is methane, a greenhouse gas 28 times more potent than carbon dioxide. Landfills are a major source of methane, which is created when organic material decomposes underground.

      Now a startup that began at MIT is aiming to significantly reduce methane emissions from landfills with a system that requires no extra land, roads, or electric lines to work. The company, Loci Controls, has developed a solar-powered system that optimizes the collection of methane from landfills so more of it can be converted into natural gas.

      At the center of Loci’s (pronounced “low-sigh”) system is a lunchbox-sized device that attaches to methane collection wells, which vacuum the methane up to the surface for processing. The optimal vacuum force changes with factors like atmospheric pressure and temperature. Loci’s system monitors those factors and adjusts the vacuum force at each well far more frequently than is possible with field technicians making manual adjustments.

      “We expect to reduce methane emissions more than any other company in the world over the next five years,” Loci Controls CEO Peter Quigley ’85 says. The company was founded by Melinda Hale Sims SM ’09, PhD ’12 and Andrew Campanella ’05, SM ’13.

      The reason for Quigley’s optimism is the high concentration of landfill methane emissions. Most landfill emissions in the U.S. come from about 1,000 large dumps. Increasing collection of methane at those sites could make a significant dent in the country’s overall emissions.

      In one landfill where Loci’s system was installed, for instance, the company says it increased methane sales at an annual rate of 180,000 metric tons of carbon dioxide equivalent. That’s about the same as removing 40,000 cars from the road for a year.

      Loci’s system is currently installed on wells in 15 different landfills. Quigley says only about 70 of the 1,000 big landfills in the U.S. sell gas profitably. Most of the others burn the gas. But Loci’s team believes increasing public and regulatory pressure will help expands its potential customer base.

      Uncovering a major problem

      The idea for Loci came from a revelation by Sims’ father, serial entrepreneur Michael Hale SM ’85, PhD ’89. The elder Hale was working in wastewater management when he was contacted by a landfill in New York that wanted help using its excess methane gas.

      “He realized if he could help that particular landfill with the problem, it would apply to almost any landfill,” Sims says.

      At the time, Sims was pursuing her PhD in mechanical engineering at MIT and minoring in entrepreneurship.

      Her father didn’t have time to work on the project, but Sims began exploring technology solutions to improve methane capture at landfills in her business classes. The work was unrelated to her PhD, but her advisor, David Hardt, the Ralph E. and Eloise F. Cross Professor in Manufacturing at MIT, was understanding. (Hardt had also served as PhD advisor for Sim’s father, who was, after all, the person to blame for Sim’s new side project.)

      Sims partnered with Andrew Campanella, then a master’s student focused on electrical engineering, and the two went through the delta v summer accelerator program hosted by the Martin Trust Center for MIT Entrepreneurship.

      Quigley was retired but serving on multiple visiting committees at MIT when he began mentoring Loci’s founders. He’d spent his career commercializing reinforced plastic through two companies, one in the high-performance sporting goods industry and the other in oil field services.

      “What captured my imagination was the emissions-reduction opportunity,” Quigley says.

      Methane is generated in landfills when organic waste decomposes. Some landfill operators capture the methane by drilling hundreds of collection wells. The vacuum pressure of those wells needs to be adjusted to maximize the amount of methane collected, but Quigley says technicians can only make those adjustments manually about once a month.

      Loci’s devices monitor gas composition, temperature, and environmental factors like barometric pressure to optimize vacuum power every hour. The data the controllers collect is aggregated in an analytics platform for technicians to monitor remotely. That data can also be used to pinpoint well failure events, such as flooding during rain, and otherwise improve operations to increase the amount of methane captured.

      “We can adjust the valves automatically, but we also have data that allows on-site operators to identify and remedy problems much more quickly,” Quigley explains.

      Furthering a high-impact mission

      Methane capture at landfills is becoming more urgent as improvements in detection technologies are revealing discrepancies between methane emission estimates and reality in the industry. A new airborne methane sensor deployed by NASA, for instance, found that California landfills have been leaking methane at rates as much as six times greater than estimates from the U.S. Environmental Protection Agency. The difference has major implications for the Earth’s atmosphere.

      A reckoning will have to occur to motivate more waste management companies to start collecting methane and to optimize methane capture. That could come in the form of new collection standards or an increased emphasis on methane collection from investors. (Funds controlled by billionaires Bill Gates and Larry Fink are major investors in waste management companies.)

      For now, Loci’s team, including co-founder and current senior advisor Sims, believes it’s on the road to making a meaningful impact under current market conditions.

      “When I was in grad school, the majority of the focus on emissions was on CO2,” Sims says. “I think methane is a really high-impact place to be focused, and I think it’s been underestimated how valuable it could be to apply technology to the industry.” More