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    Study finds lands used for grazing can worsen or help climate change

    When it comes to global climate change, livestock grazing can be either a blessing or a curse, according to a new study, which offers clues on how to tell the difference.

    If managed properly, the study shows, grazing can actually increase the amount of carbon from the air that gets stored in the ground and sequestered for the long run. But if there is too much grazing, soil erosion can result, and the net effect is to cause more carbon losses, so that the land becomes a net carbon source, instead of a carbon sink. And the study found that the latter is far more common around the world today.

    The new work, published today in the journal Nature Climate Change, provides ways to determine the tipping point between the two, for grazing lands in a given climate zone and soil type. It also provides an estimate of the total amount of carbon that has been lost over past decades due to livestock grazing, and how much could be removed from the atmosphere if grazing optimization management implemented. The study was carried out by Cesar Terrer, an assistant professor of civil and environmental engineering at MIT; Shuai Ren, a PhD student at the Chinese Academy of Sciences whose thesis is co-supervised by Terrer; and four others.

    “This has been a matter of debate in the scientific literature for a long time,” Terrer says. “In general experiments, grazing decreases soil carbon stocks, but surprisingly, sometimes grazing increases soil carbon stocks, which is why it’s been puzzling.”

    What happens, he explains, is that “grazing could stimulate vegetation growth through easing resource constraints such as light and nutrients, thereby increasing root carbon inputs to soils, where carbon can stay there for centuries or millennia.”

    But that only works up to a certain point, the team found after a careful analysis of 1,473 soil carbon observations from different grazing studies from many locations around the world. “When you cross a threshold in grazing intensity, or the amount of animals grazing there, that is when you start to see sort of a tipping point — a strong decrease in the amount of carbon in the soil,” Terrer explains.

    That loss is thought to be primarily from increased soil erosion on the denuded land. And with that erosion, Terrer says, “basically you lose a lot of the carbon that you have been locking in for centuries.”

    The various studies the team compiled, although they differed somewhat, essentially used similar methodology, which is to fence off a portion of land so that livestock can’t access it, and then after some time take soil samples from within the enclosure area, and from comparable nearby areas that have been grazed, and compare the content of carbon compounds.

    “Along with the data on soil carbon for the control and grazed plots,” he says, “we also collected a bunch of other information, such as the mean annual temperature of the site, mean annual precipitation, plant biomass, and properties of the soil, like pH and nitrogen content. And then, of course, we estimate the grazing intensity — aboveground biomass consumed, because that turns out to be the key parameter.”  

    With artificial intelligence models, the authors quantified the importance of each of these parameters, those drivers of intensity — temperature, precipitation, soil properties — in modulating the sign (positive or negative) and magnitude of the impact of grazing on soil carbon stocks. “Interestingly, we found soil carbon stocks increase and then decrease with grazing intensity, rather than the expected linear response,” says Ren.

    Having developed the model through AI methods and validated it, including by comparing its predictions with those based on underlying physical principles, they can then apply the model to estimating both past and future effects. “In this case,” Terrer says, “we use the model to quantify the historical loses in soil carbon stocks from grazing. And we found that 46 petagrams [billion metric tons] of soil carbon, down to a depth of one meter, have been lost in the last few decades due to grazing.”

    By way of comparison, the total amount of greenhouse gas emissions per year from all fossil fuels is about 10 petagrams, so the loss from grazing equals more than four years’ worth of all the world’s fossil emissions combined.

    What they found was “an overall decline in soil carbon stocks, but with a lot of variability.” Terrer says. The analysis showed that the interplay between grazing intensity and environmental conditions such as temperature could explain the variability, with higher grazing intensity and hotter climates resulting in greater carbon loss. “This means that policy-makers should take into account local abiotic and biotic factors to manage rangelands efficiently,” Ren notes. “By ignoring such complex interactions, we found that using IPCC [Intergovernmental Panel on Climate Change] guidelines would underestimate grazing-induced soil carbon loss by a factor of three globally.”

    Using an approach that incorporates local environmental conditions, the team produced global, high-resolution maps of optimal grazing intensity and the threshold of intensity at which carbon starts to decrease very rapidly. These maps are expected to serve as important benchmarks for evaluating existing grazing practices and provide guidance to local farmers on how to effectively manage their grazing lands.

    Then, using that map, the team estimated how much carbon could be captured if all grazing lands were limited to their optimum grazing intensity. Currently, the authors found, about 20 percent of all pasturelands have crossed the thresholds, leading to severe carbon losses. However, they found that under the optimal levels, global grazing lands would sequester 63 petagrams of carbon. “It is amazing,” Ren says. “This value is roughly equivalent to a 30-year carbon accumulation from global natural forest regrowth.”

    That would be no simple task, of course. To achieve optimal levels, the team found that approximately 75 percent of all grazing areas need to reduce grazing intensity. Overall, if the world seriously reduces the amount of grazing, “you have to reduce the amount of meat that’s available for people,” Terrer says.

    “Another option is to move cattle around,” he says, “from areas that are more severely affected by grazing intensity, to areas that are less affected. Those rotations have been suggested as an opportunity to avoid the more drastic declines in carbon stocks without necessarily reducing the availability of meat.”

    This study didn’t delve into these social and economic implications, Terrer says. “Our role is to just point out what would be the opportunity here. It shows that shifts in diets can be a powerful way to mitigate climate change.”

    “This is a rigorous and careful analysis that provides our best look to date at soil carbon changes due to livestock grazing practiced worldwide,” say Ben Bond-Lamberty, a terrestrial ecosystem research scientist at Pacific Northwest National Laboratory, who was not associated with this work. “The authors’ analysis gives us a unique estimate of soil carbon losses due to grazing and, intriguingly, where and how the process might be reversed.”

    He adds: “One intriguing aspect to this work is the discrepancies between its results and the guidelines currently used by the IPCC — guidelines that affect countries’ commitments, carbon-market pricing, and policies.” However, he says, “As the authors note, the amount of carbon historically grazed soils might be able to take up is small relative to ongoing human emissions. But every little bit helps!”

    “Improved management of working lands can be a powerful tool to combat climate change,” says Jonathan Sanderman, carbon program director of the Woodwell Climate Research Center in Falmouth, Massachusetts, who was not associated with this work. He adds, “This work demonstrates that while, historically, grazing has been a large contributor to climate change, there is significant potential to decrease the climate impact of livestock by optimizing grazing intensity to rebuild lost soil carbon.”

    Terrer states that for now, “we have started a new study, to evaluate the consequences of shifts in diets for carbon stocks. I think that’s the million-dollar question: How much carbon could you sequester, compared to business as usual, if diets shift to more vegan or vegetarian?” The answers will not be simple, because a shift to more vegetable-based diets would require more cropland, which can also have different environmental impacts. Pastures take more land than crops, but produce different kinds of emissions. “What’s the overall impact for climate change? That is the question we’re interested in,” he says.

    The research team included Juan Li, Yingfao Cao, Sheshan Yang, and Dan Liu, all with the  Chinese Academy of Sciences. The work was supported by the Second Tibetan Plateau Scientific Expedition and Research Program, and the Science and Technology Major Project of Tibetan Autonomous Region of China. More

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    Letting the Earth answer back: Designing better planetary conversations

    For Chen Chu MArch ’21, the invitation to join the 2023-24 cohort of Morningside Academy for Design Design Fellows has been an unparalleled opportunity to investigate the potential of design as an alternative method of problem-solving.

    After earning a master’s degree in architecture at MIT and gaining professional experience as a researcher at an environmental nongovernmental organization, Chu decided to pursue a PhD in the Department of Urban Studies and Planning. “I discovered that I needed to engage in a deeper way with the most difficult ethical challenges of our time, especially those arising from the fact of climate change,” he explains. “For me, MIT has always represented this wonderful place where people are inherently intellectually curious — it’s a very rewarding community to be part of.”

    Chu’s PhD research, guided by his doctoral advisor Delia Wendel, assistant professor of urban studies and international development, focuses on how traditional practices of floodplain agriculture can inform local and global strategies for sustainable food production and distribution in response to climate change. 

    Typically located alongside a river or stream, floodplains arise from seasonal flooding patterns that distribute nutrient-rich silt and create connectivity between species. This results in exceptionally high levels of biodiversity and microbial richness, generating the ideal conditions for agriculture. It’s no accident that the first human civilizations were founded on floodplains, including Mesopotamia (named for its location poised between two rivers, the Euphrates and Tigris), the Indus River Civilization, and the cultures of Ancient Egypt based around the Nile. Riverine transportation networks and predictable flooding rhythms provide a framework for trade and cultivation; nonetheless, floodplain communities must learn to live with risk, subject to the sudden disruptions of high waters, drought, and ecological disequilibrium. 

    For Chu, the “unstable and ungovernable” status of floodplains makes them fertile ground for thinking about. “I’m drawn to these so-called ‘wet landscapes’ — edge conditions that act as transitional spaces between land and water, between humans and nature, between city and river,” he reflects. “The development of extensively irrigated agricultural sites is typically a collective effort, which raises intriguing questions about how communities establish social organizations that simultaneously negotiate top-down state control and adapt to the uncertainty of nature.”

    Chu is in the process of honing the focus of his dissertation and refining his data collection methods, which will include archival research and fieldwork, as well as interviews with floodplain inhabitants to gain an understanding of sociopolitical nuances. Meanwhile, his role as a design fellow gives him the space to address the big questions that fire his imagination. How can we live well on shared land? How can we take responsibility for the lives of future generations? What types of political structures are required to get everyone on board? 

    These are just a few of the questions that Chu recently put to his cohort in a presentation. During the weekly seminars for the fellowship, he has the chance to converse with peers and mentors of multiple disciplines — from researchers rethinking the pedagogy of design to entrepreneurs applying design thinking to new business models to architects and engineers developing new habitats to heal our relationship with the natural world. 

    “I’ll admit — I’m wary of the human instinct to problem-solve,” says Chu. “When it comes to the material conditions and lived experience of people and planet, there’s a limit to our economic and political reasoning, and to conventional architectural practice. That said, I do believe that the mindset of a designer can open up new ways of thinking. At its core, design is an interdisciplinary practice based on the understanding that a problem can’t be solved from a narrow, singular perspective.” 

    The stimulating structure of a MAD Fellowship — free from immediate obligations to publish or produce, fellows learn from one another and engage with visiting speakers via regular seminars and events — has prompted Chu to consider what truly makes for generative conversation in the contexts of academia and the private and public sectors. In his opinion, discussions around climate change often fail to take account of one important voice; an absence he describes as “that silent being, the Earth.”

    “You can’t ask the Earth, ‘What does justice mean to you?’ Nature will not respond,” he reflects. To bridge the gap, Chu believes it’s important to combine the study of specific political and social conditions with broader existential questions raised by the environmental humanities. His own research draws upon the perspectives of thinkers including Dipesh Chakrabarty, Donna Haraway, Peter Singer,  Anna Tsing, and Michael Watts, among others. He cites James C. Scott’s lecture “In Praise of Floods” as one of his most important influences.

    In addition to his instinctive appreciation for theory, Chu’s outlook is grounded by an attention to innovation at the local level. He is currently establishing the parameters of his research, examining case studies of agricultural systems and flood mitigation strategies that have been sustained for centuries. 

    “One example is the polder system that is practiced in the Netherlands, China, Bangladesh, and many parts of the world: small, low-lying tracts of land submerged in water and surrounded by dykes and canals,” he explains. “You’ll find a different but comparable strategy in the colder regions of Japan. Crops are protected from the winter winds by constructing a spatial unit with the house at the center; trees behind the house serve as windbreakers and paddy fields for rice are located in front of the house, providing an integrated system of food and livelihood security.”

    Chu observes that there is a tendency for international policymakers to overlook local solutions in favor of grander visions and ambitious climate pledges — but he is equally keen not to romanticize vernacular practices. “Realistically, it’s always a two-way interaction. Unless you already have a workable local system in place, it’s difficult to implement a solution without top-down support. On the other hand, the large-scale technocratic dreams are empty if ignorant of local traditions and histories.” 

    By navigating between the global and the local, the theoretical and the practical, the visionary and the cautionary, Chu has hope in the possibility of gradually finding a way toward long-term solutions that adapt to specific conditions over time. It’s a model of ambition and criticality that Chu sees played out during dialogue at MAD and within his department; at root, he’s aware that the outcome of these conversations depends on the ethical context that shapes them.

    “I’ve been fortunate to have many mentors who have taught me the power of humility; a respect for the finitude, fragility,  and uncertainty of life,” he recalls. “It’s a mindset that’s barely apparent in today’s push for economic growth.” The flip-side of hubristic growth is an assumption that technological ingenuity will be enough to solve the climate crisis, but Chu’s optimism arises from a different source: “When I feel overwhelmed by the weight of the problems we’re facing, I just need to look around me,” he says. “Here on campus — at MAD, in my home department, and increasingly among the new generations of students — there’s a powerful ethos of political sensitivity, ethical compassion, and an attention to clear and critical judgment. That always gives me hope for the planet.” More

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    Reducing pesticide use while increasing effectiveness

    Farming can be a low-margin, high-risk business, subject to weather and climate patterns, insect population cycles, and other unpredictable factors. Farmers need to be savvy managers of the many resources they deal, and chemical fertilizers and pesticides are among their major recurring expenses.

    Despite the importance of these chemicals, a lack of technology that monitors and optimizes sprays has forced farmers to rely on personal experience and rules of thumb to decide how to apply these chemicals. As a result, these chemicals tend to be over-sprayed, leading to their runoff into waterways and buildup up in the soil.

    That could change, thanks to a new approach of feedback-optimized spraying, invented by AgZen, an MIT spinout founded in 2020 by Professor Kripa Varanasi and Vishnu Jayaprakash SM ’19, PhD ’22.

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    AgZen has developed a system for farming that can monitor exactly how much of the sprayed chemicals adheres to plants, in real time, as the sprayer drives through a field. Built-in software running on a tablet shows the operator exactly how much of each leaf has been covered by the spray.

    Over the past decade, AgZen’s founders have developed products and technologies to control the interactions of droplets and sprays with plant surfaces. The Boston-based venture-backed company launched a new commercial product in 2024 and is currently piloting another related product. Field tests of both have shown the products can help farmers spray more efficiently and effectively, using fewer chemicals overall.

    “Worldwide, farms spend approximately $60 billion a year on pesticides. Our objective is to reduce the number of pesticides sprayed and lighten the financial burden on farms without sacrificing effective pest management,” Varanasi says.

    Getting droplets to stick

    While the world pesticide market is growing rapidly, a lot of the pesticides sprayed don’t reach their target. A significant portion bounces off the plant surfaces, lands on the ground, and becomes part of the runoff that flows to streams and rivers, often causing serious pollution. Some of these pesticides can be carried away by wind over very long distances.

    “Drift, runoff, and poor application efficiency are well-known, longstanding problems in agriculture, but we can fix this by controlling and monitoring how sprayed droplets interact with leaves,” Varanasi says.

    With support from MIT Tata Center and the Abdul Latif Jameel Water and Food Systems Lab, Varanasi and his team analyzed how droplets strike plant surfaces, and explored ways to increase application efficiency. This research led them to develop a novel system of nozzles that cloak droplets with compounds that enhance the retention of droplets on the leaves, a product they call EnhanceCoverage.

    Field studies across regions — from Massachusetts to California to Italy and France —showed that this droplet-optimization system could allow farmers to cut the amount of chemicals needed by more than half because more of the sprayed substances would stick to the leaves.

    Measuring coverage

    However, in trying to bring this technology to market, the researchers faced a sticky problem: Nobody knew how well pesticide sprays were adhering to the plants in the first place, so how could AgZen say that the coverage was better with its new EnhanceCoverage system?

    “I had grown up spraying with a backpack on a small farm in India, so I knew this was an issue,” Jayaprakash says. “When we spoke to growers, they told me how complicated spraying is when you’re on a large machine. Whenever you spray, there are so many things that can influence how effective your spray is. How fast do you drive the sprayer? What flow rate are you using for the chemicals? What chemical are you using? What’s the age of the plants, what’s the nozzle you’re using, what is the weather at the time? All these things influence agrochemical efficiency.”

    Agricultural spraying essentially comes down to dissolving a chemical in water and then spraying droplets onto the plants. “But the interaction between a droplet and the leaf is complex,” Varanasi says. “We were coming in with ways to optimize that, but what the growers told us is, hey, we’ve never even really looked at that in the first place.”

    Although farmers have been spraying agricultural chemicals on a large scale for about 80 years, they’ve “been forced to rely on general rules of thumb and pick all these interlinked parameters, based on what’s worked for them in the past. You pick a set of these parameters, you go spray, and you’re basically praying for outcomes in terms of how effective your pest control is,” Varanasi says.

    Before AgZen could sell farmers on the new system to improve droplet coverage, the company had to invent a way to measure precisely how much spray was adhering to plants in real-time.

    Comparing before and after

    The system they came up with, which they tested extensively on farms across the country last year, involves a unit that can be bolted onto the spraying arm of virtually any sprayer. It carries two sensor stacks, one just ahead of the sprayer nozzles and one behind. Then, built-in software running on a tablet shows the operator exactly how much of each leaf has been covered by the spray. It also computes how much those droplets will spread out or evaporate, leading to a precise estimate of the final coverage.

    “There’s a lot of physics that governs how droplets spread and evaporate, and this has been incorporated into software that a farmer can use,” Varanasi says. “We bring a lot of our expertise into understanding droplets on leaves. All these factors, like how temperature and humidity influence coverage, have always been nebulous in the spraying world. But now you have something that can be exact in determining how well your sprays are doing.”

    “We’re not only measuring coverage, but then we recommend how to act,” says Jayaprakash, who is AgZen’s CEO. “With the information we collect in real-time and by using AI, RealCoverage tells operators how to optimize everything on their sprayer, from which nozzle to use, to how fast to drive, to how many gallons of spray is best for a particular chemical mix on a particular acre of a crop.”

    The tool was developed to prove how much AgZen’s EnhanceCoverage nozzle system (which will be launched in 2025) improves coverage. But it turns out that monitoring and optimizing droplet coverage on leaves in real-time with this system can itself yield major improvements.

    “We worked with large commercial farms last year in specialty and row crops,” Jayaprakash says. “When we saved our pilot customers up to 50 percent of their chemical cost at a large scale, they were very surprised.” He says the tool has reduced chemical costs and volume in fallow field burndowns, weed control in soybeans, defoliation in cotton, and fungicide and insecticide sprays in vegetables and fruits. Along with data from commercial farms, field trials conducted by three leading agricultural universities have also validated these results.

    “Across the board, we were able to save between 30 and 50 percent on chemical costs and increase crop yields by enabling better pest control,” Jayaprakash says. “By focusing on the droplet-leaf interface, our product can help any foliage spray throughout the year, whereas most technological advancements in this space recently have been focused on reducing herbicide use alone.” The company now intends to lease the system across thousands of acres this year.

    And these efficiency gains can lead to significant returns at scale, he emphasizes: In the U.S., farmers currently spend $16 billion a year on chemicals, to protect about $200 billion of crop yields.

    The company launched its first product, the coverage optimization system called RealCoverage, this year, reaching a wide variety of farms with different crops and in different climates. “We’re going from proof-of-concept with pilots in large farms to a truly massive scale on a commercial basis with our lease-to-own program,” Jayaprakash says.

    “We’ve also been tapped by the USDA to help them evaluate practices to minimize pesticides in watersheds,” Varanasi says, noting that RealCoverage can also be useful for regulators, chemical companies, and agricultural equipment manufacturers.

    Once AgZen has proven the effectiveness of using coverage as a decision metric, and after the RealCoverage optimization system is widely in practice, the company will next roll out its second product, EnhanceCoverage, designed to maximize droplet adhesion. Because that system will require replacing all the nozzles on a sprayer, the researchers are doing pilots this year but will wait for a full rollout in 2025, after farmers have gained experience and confidence with their initial product.

    “There is so much wastage,” Varanasi says. “Yet farmers must spray to protect crops, and there is a lot of environmental impact from this. So, after all this work over the years, learning about how droplets stick to surfaces and so on, now the culmination of it in all these products for me is amazing, to see all this come alive, to see that we’ll finally be able to solve the problem we set out to solve and help farmers.” More

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    At Sustainability Connect 2024, a look at how MIT is decarbonizing its campus

    How is MIT working to meet its goal of decarbonizing the campus by 2050? How are local journalists communicating climate impacts and solutions to diverse audiences? What can each of us do to bring our unique skills and insight to tackle the challenges of climate and sustainability?

    These are all questions asked — and answered — at Sustainability Connect, the yearly forum hosted by the MIT Office of Sustainability that offers an inside look at this transformative and comprehensive work that is the foundation for MIT’s climate and sustainability leadership on campus. The event invites individuals in every role at MIT to learn more about the sustainability and climate work happening on campus and to share their ideas, highlight important work, and find new ways to plug into ongoing efforts. “This event is a reminder of the remarkable, diverse, and committed group of colleagues we are all part of at MIT,” said Director of Sustainability Julie Newman as the event kicked off alongside Interfaith Chaplain and Spiritual Advisor to the Indigenous Community Nina Lytton, who offered a moment of connection to attendees. At the event, that diverse and committed group was made up of more than 130 community members representing more than 70 departments, labs, and centers.

    This year, Sustainability Connect was timed with announcement of the new Climate Project at MIT, with Vice Provost Richard Lester joining the event to expound on MIT’s deep commitment to tackling the climate challenge over the next 10 years through a series of climate missions — many of which build upon the ongoing research taking place across campus already. In introducing the Climate Project at MIT, Lester echoed the theme of connection and collaboration. “This plan is about helping bridge the gap between what we would accomplish as a collection of energetic, talented, ambitious individuals, and what we’re capable of if we act together,” he said.

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    Sustainability Connect 2024: Decarbonizing the Campus Video: MIT Office of Sustainability

    Highlighting one of the many collaborative efforts to address MIT’s contributions to climate change was the Decarbonizing the Campus panel, which provided a real-time look at MIT’s work to eliminate carbon emissions from campus by 2050. Newman and Vice President for Campus Services and Stewardship Joe Higgins, along with Senior Campus Planner Vasso Mathes, Senior Sustainability Project Manager Steve Lanou, and PhD student Chenhan Shao, shared the many ways MIT is working to decarbonize its campus now and respond to evolving technologies and policies in the future. “A third of MIT’s faculty and researchers … are working to identify ways in which MIT can amplify its contributions to addressing the world’s climate crisis. But part and parcel to that goal is we’re putting significant effort into decarbonizing MIT’S own carbon footprint here on our campus,” Higgins said before highlighting how MIT continues to work on projects focused on building efficiency, renewable energy on campus and off, and support of a cleaner grid, among many decarbonization strategies.

    Newman shared the way in which climate education and research play an important role through the Decarbonization Working Group research streams, and courses like class 4.s42 (Carbon Reduction Pathways for the MIT Campus) offered by Professor Christoph Reinhart. Lanou and Shao also showcased how MIT is optimizing its response to Cambridge’s Building Energy Use Disclosure Ordinance, which is aimed at tracking and reducing emissions from large commercial properties in the city with a goal of net-zero buildings by 2035. “We’ve been able [create] pathways that would be practical, innovative, have a high degree of accountability, and that could work well within the structures and the limitations that we have,” Lanou said before debuting a dashboard he and Shao developed during Independent Activities Period to track and forecast work to meet the Cambridge goal. 

    MIT’s robust commitment to decarbonize its campus goes beyond energy systems, as highlighted by the work of many staff members who led roundtables as part of Sustainability in Motion, where attendees were invited to sit down with colleagues from across campus responsible for implementing the numerous climate and sustainability commitments. Teams reported out on progress to date on a range of efforts including sustainable food systems, safe and sustainable labs, and procurement. “Tackling the unprecedented challenges of a changing planet in and around MIT takes the support of individuals and teams from all corners of the Institute,” said Assistant Director of Sustainability Brian Goldberg in leading the session. “Whether folks have sustainability or climate in their job title, or they’ve contributed countless volunteer hours to the cause, our community members are leading many meaningful efforts to transform MIT.”

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    Sustainability Connect 2024: Climate in the Media PanelVideo: Office of Sustainability

    The day culminated with a panel on climate in the media, taking the excitement from the room and putting it in context — how do you translate this work, these solutions, and these challenges for a diverse audience with an ever-changing appetite for these kinds of stories? Laur Hesse Fisher, program director for the Environmental Solutions Initiate (ESI); Barbara Moran, climate and environment reporter at WBUR radio; and independent climate journalist Annie Ropeik joined the panel moderated by Knight Science Journalism Program at MIT Director Deborah Blum. Blum spoke of the current mistrust of not only the media but of news stories of climate impacts and even solutions. “To those of us telling the story of climate change, how do we reach resistant audiences? How do we gain their trust?” she asked.

    Fisher, who hosts the TIL Climate podcast and leads the ESI Journalism Fellowship, explained how she shifts her approach depending on her audience. “[With TIL Climate], a lot of what we do is, we try to understand what kinds of questions people have,” she said. “We have people submit questions to us, and then we answer them in language that they can understand.”

    For Moran, reaching audiences relies on finding the right topic to bridge to deeper issues. On a recent story about solar arrays and their impact on forests and the landscape around them, Moran saw bees and pollinators as the way in. “I can talk about bees and flowers. And that will hook people enough to get in. And then through that, we can address this issue of forest versus commercial solar and this tension, and what can be done to address that, and what’s working and what’s not,” she said.

    The panel highlighted that even as climate solutions and challenges become clearer, communicating them can remain a challenge. “Sustainability Connect is invaluable when it comes to sharing our work and bringing more people in, but over the years, it’s become clear how many people are still outside of these conversations,” said Newman. “Capping the day off with this conversation on climate in the media served as a jumping-off point for all of us to think how we can better communicate our efforts and tackle the challenges that keep us from bringing everyone to the table to help us find and share solutions for addressing climate change. It’s just the beginning of this conversation.” More

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    Tests show high-temperature superconducting magnets are ready for fusion

    In the predawn hours of Sept. 5, 2021, engineers achieved a major milestone in the labs of MIT’s Plasma Science and Fusion Center (PSFC), when a new type of magnet, made from high-temperature superconducting material, achieved a world-record magnetic field strength of 20 tesla for a large-scale magnet. That’s the intensity needed to build a fusion power plant that is expected to produce a net output of power and potentially usher in an era of virtually limitless power production.

    The test was immediately declared a success, having met all the criteria established for the design of the new fusion device, dubbed SPARC, for which the magnets are the key enabling technology. Champagne corks popped as the weary team of experimenters, who had labored long and hard to make the achievement possible, celebrated their accomplishment.

    But that was far from the end of the process. Over the ensuing months, the team tore apart and inspected the components of the magnet, pored over and analyzed the data from hundreds of instruments that recorded details of the tests, and performed two additional test runs on the same magnet, ultimately pushing it to its breaking point in order to learn the details of any possible failure modes.

    All of this work has now culminated in a detailed report by researchers at PSFC and MIT spinout company Commonwealth Fusion Systems (CFS), published in a collection of six peer-reviewed papers in a special edition of the March issue of IEEE Transactions on Applied Superconductivity. Together, the papers describe the design and fabrication of the magnet and the diagnostic equipment needed to evaluate its performance, as well as the lessons learned from the process. Overall, the team found, the predictions and computer modeling were spot-on, verifying that the magnet’s unique design elements could serve as the foundation for a fusion power plant.

    Enabling practical fusion power

    The successful test of the magnet, says Hitachi America Professor of Engineering Dennis Whyte, who recently stepped down as director of the PSFC, was “the most important thing, in my opinion, in the last 30 years of fusion research.”

    Before the Sept. 5 demonstration, the best-available superconducting magnets were powerful enough to potentially achieve fusion energy — but only at sizes and costs that could never be practical or economically viable. Then, when the tests showed the practicality of such a strong magnet at a greatly reduced size, “overnight, it basically changed the cost per watt of a fusion reactor by a factor of almost 40 in one day,” Whyte says.

    “Now fusion has a chance,” Whyte adds. Tokamaks, the most widely used design for experimental fusion devices, “have a chance, in my opinion, of being economical because you’ve got a quantum change in your ability, with the known confinement physics rules, about being able to greatly reduce the size and the cost of objects that would make fusion possible.”

    The comprehensive data and analysis from the PSFC’s magnet test, as detailed in the six new papers, has demonstrated that plans for a new generation of fusion devices — the one designed by MIT and CFS, as well as similar designs by other commercial fusion companies — are built on a solid foundation in science.

    The superconducting breakthrough

    Fusion, the process of combining light atoms to form heavier ones, powers the sun and stars, but harnessing that process on Earth has proved to be a daunting challenge, with decades of hard work and many billions of dollars spent on experimental devices. The long-sought, but never yet achieved, goal is to build a fusion power plant that produces more energy than it consumes. Such a power plant could produce electricity without emitting greenhouse gases during operation, and generating very little radioactive waste. Fusion’s fuel, a form of hydrogen that can be derived from seawater, is virtually limitless.

    But to make it work requires compressing the fuel at extraordinarily high temperatures and pressures, and since no known material could withstand such temperatures, the fuel must be held in place by extremely powerful magnetic fields. Producing such strong fields requires superconducting magnets, but all previous fusion magnets have been made with a superconducting material that requires frigid temperatures of about 4 degrees above absolute zero (4 kelvins, or -270 degrees Celsius). In the last few years, a newer material nicknamed REBCO, for rare-earth barium copper oxide, was added to fusion magnets, and allows them to operate at 20 kelvins, a temperature that despite being only 16 kelvins warmer, brings significant advantages in terms of material properties and practical engineering.

    Taking advantage of this new higher-temperature superconducting material was not just a matter of substituting it in existing magnet designs. Instead, “it was a rework from the ground up of almost all the principles that you use to build superconducting magnets,” Whyte says. The new REBCO material is “extraordinarily different than the previous generation of superconductors. You’re not just going to adapt and replace, you’re actually going to innovate from the ground up.” The new papers in Transactions on Applied Superconductivity describe the details of that redesign process, now that patent protection is in place.

    A key innovation: no insulation

    One of the dramatic innovations, which had many others in the field skeptical of its chances of success, was the elimination of insulation around the thin, flat ribbons of superconducting tape that formed the magnet. Like virtually all electrical wires, conventional superconducting magnets are fully protected by insulating material to prevent short-circuits between the wires. But in the new magnet, the tape was left completely bare; the engineers relied on REBCO’s much greater conductivity to keep the current flowing through the material.

    “When we started this project, in let’s say 2018, the technology of using high-temperature superconductors to build large-scale high-field magnets was in its infancy,” says Zach Hartwig, the Robert N. Noyce Career Development Professor in the Department of Nuclear Science and Engineering. Hartwig has a co-appointment at the PSFC and is the head of its engineering group, which led the magnet development project. “The state of the art was small benchtop experiments, not really representative of what it takes to build a full-size thing. Our magnet development project started at benchtop scale and ended up at full scale in a short amount of time,” he adds, noting that the team built a 20,000-pound magnet that produced a steady, even magnetic field of just over 20 tesla — far beyond any such field ever produced at large scale.

    “The standard way to build these magnets is you would wind the conductor and you have insulation between the windings, and you need insulation to deal with the high voltages that are generated during off-normal events such as a shutdown.” Eliminating the layers of insulation, he says, “has the advantage of being a low-voltage system. It greatly simplifies the fabrication processes and schedule.” It also leaves more room for other elements, such as more cooling or more structure for strength.

    The magnet assembly is a slightly smaller-scale version of the ones that will form the donut-shaped chamber of the SPARC fusion device now being built by CFS in Devens, Massachusetts. It consists of 16 plates, called pancakes, each bearing a spiral winding of the superconducting tape on one side and cooling channels for helium gas on the other.

    But the no-insulation design was considered risky, and a lot was riding on the test program. “This was the first magnet at any sufficient scale that really probed what is involved in designing and building and testing a magnet with this so-called no-insulation no-twist technology,” Hartwig says. “It was very much a surprise to the community when we announced that it was a no-insulation coil.”

    Pushing to the limit … and beyond

    The initial test, described in previous papers, proved that the design and manufacturing process not only worked but was highly stable — something that some researchers had doubted. The next two test runs, also performed in late 2021, then pushed the device to the limit by deliberately creating unstable conditions, including a complete shutoff of incoming power that can lead to a catastrophic overheating. Known as quenching, this is considered a worst-case scenario for the operation of such magnets, with the potential to destroy the equipment.

    Part of the mission of the test program, Hartwig says, was “to actually go off and intentionally quench a full-scale magnet, so that we can get the critical data at the right scale and the right conditions to advance the science, to validate the design codes, and then to take the magnet apart and see what went wrong, why did it go wrong, and how do we take the next iteration toward fixing that. … It was a very successful test.”

    That final test, which ended with the melting of one corner of one of the 16 pancakes, produced a wealth of new information, Hartwig says. For one thing, they had been using several different computational models to design and predict the performance of various aspects of the magnet’s performance, and for the most part, the models agreed in their overall predictions and were well-validated by the series of tests and real-world measurements. But in predicting the effect of the quench, the model predictions diverged, so it was necessary to get the experimental data to evaluate the models’ validity.

    “The highest-fidelity models that we had predicted almost exactly how the magnet would warm up, to what degree it would warm up as it started to quench, and where would the resulting damage to the magnet would be,” he says. As described in detail in one of the new reports, “That test actually told us exactly the physics that was going on, and it told us which models were useful going forward and which to leave by the wayside because they’re not right.”

    Whyte says, “Basically we did the worst thing possible to a coil, on purpose, after we had tested all other aspects of the coil performance. And we found that most of the coil survived with no damage,” while one isolated area sustained some melting. “It’s like a few percent of the volume of the coil that got damaged.” And that led to revisions in the design that are expected to prevent such damage in the actual fusion device magnets, even under the most extreme conditions.

    Hartwig emphasizes that a major reason the team was able to accomplish such a radical new record-setting magnet design, and get it right the very first time and on a breakneck schedule, was thanks to the deep level of knowledge, expertise, and equipment accumulated over decades of operation of the Alcator C-Mod tokamak, the Francis Bitter Magnet Laboratory, and other work carried out at PSFC. “This goes to the heart of the institutional capabilities of a place like this,” he says. “We had the capability, the infrastructure, and the space and the people to do these things under one roof.”

    The collaboration with CFS was also key, he says, with MIT and CFS combining the most powerful aspects of an academic institution and private company to do things together that neither could have done on their own. “For example, one of the major contributions from CFS was leveraging the power of a private company to establish and scale up a supply chain at an unprecedented level and timeline for the most critical material in the project: 300 kilometers (186 miles) of high-temperature superconductor, which was procured with rigorous quality control in under a year, and integrated on schedule into the magnet.”

    The integration of the two teams, those from MIT and those from CFS, also was crucial to the success, he says. “We thought of ourselves as one team, and that made it possible to do what we did.” More

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    Power when the sun doesn’t shine

    In 2016, at the huge Houston energy conference CERAWeek, MIT materials scientist Yet-Ming Chiang found himself talking to a Tesla executive about a thorny problem: how to store the output of solar panels and wind turbines for long durations.        

    Chiang, the Kyocera Professor of Materials Science and Engineering, and Mateo Jaramillo, a vice president at Tesla, knew that utilities lacked a cost-effective way to store renewable energy to cover peak levels of demand and to bridge the gaps during windless and cloudy days. They also knew that the scarcity of raw materials used in conventional energy storage devices needed to be addressed if renewables were ever going to displace fossil fuels on the grid at scale.

    Energy storage technologies can facilitate access to renewable energy sources, boost the stability and reliability of power grids, and ultimately accelerate grid decarbonization. The global market for these systems — essentially large batteries — is expected to grow tremendously in the coming years. A study by the nonprofit LDES (Long Duration Energy Storage) Council pegs the long-duration energy storage market at between 80 and 140 terawatt-hours by 2040. “That’s a really big number,” Chiang notes. “Every 10 people on the planet will need access to the equivalent of one EV [electric vehicle] battery to support their energy needs.”

    In 2017, one year after they met in Houston, Chiang and Jaramillo joined forces to co-found Form Energy in Somerville, Massachusetts, with MIT graduates Marco Ferrara SM ’06, PhD ’08 and William Woodford PhD ’13, and energy storage veteran Ted Wiley.

    “There is a burgeoning market for electrical energy storage because we want to achieve decarbonization as fast and as cost-effectively as possible,” says Ferrara, Form’s senior vice president in charge of software and analytics.

    Investors agreed. Over the next six years, Form Energy would raise more than $800 million in venture capital.

    Bridging gaps

    The simplest battery consists of an anode, a cathode, and an electrolyte. During discharge, with the help of the electrolyte, electrons flow from the negative anode to the positive cathode. During charge, external voltage reverses the process. The anode becomes the positive terminal, the cathode becomes the negative terminal, and electrons move back to where they started. Materials used for the anode, cathode, and electrolyte determine the battery’s weight, power, and cost “entitlement,” which is the total cost at the component level.

    During the 1980s and 1990s, the use of lithium revolutionized batteries, making them smaller, lighter, and able to hold a charge for longer. The storage devices Form Energy has devised are rechargeable batteries based on iron, which has several advantages over lithium. A big one is cost.

    Chiang once declared to the MIT Club of Northern California, “I love lithium-ion.” Two of the four MIT spinoffs Chiang founded center on innovative lithium-ion batteries. But at hundreds of dollars a kilowatt-hour (kWh) and with a storage capacity typically measured in hours, lithium-ion was ill-suited for the use he now had in mind.

    The approach Chiang envisioned had to be cost-effective enough to boost the attractiveness of renewables. Making solar and wind energy reliable enough for millions of customers meant storing it long enough to fill the gaps created by extreme weather conditions, grid outages, and when there is a lull in the wind or a few days of clouds.

    To be competitive with legacy power plants, Chiang’s method had to come in at around $20 per kilowatt-hour of stored energy — one-tenth the cost of lithium-ion battery storage.

    But how to transition from expensive batteries that store and discharge over a couple of hours to some as-yet-undefined, cheap, longer-duration technology?

    “One big ball of iron”

    That’s where Ferrara comes in. Ferrara has a PhD in nuclear engineering from MIT and a PhD in electrical engineering and computer science from the University of L’Aquila in his native Italy. In 2017, as a research affiliate at the MIT Department of Materials Science and Engineering, he worked with Chiang to model the grid’s need to manage renewables’ intermittency.

    How intermittent depends on where you are. In the United States, for instance, there’s the windy Great Plains; the sun-drenched, relatively low-wind deserts of Arizona, New Mexico, and Nevada; and the often-cloudy Pacific Northwest.

    Ferrara, in collaboration with Professor Jessika Trancik of MIT’s Institute for Data, Systems, and Society and her MIT team, modeled four representative locations in the United States and concluded that energy storage with capacity costs below roughly $20/kWh and discharge durations of multiple days would allow a wind-solar mix to provide cost-competitive, firm electricity in resource-abundant locations.

    Now that they had a time frame, they turned their attention to materials. At the price point Form Energy was aiming for, lithium was out of the question. Chiang looked at plentiful and cheap sulfur. But a sulfur, sodium, water, and air battery had technical challenges.

    Thomas Edison once used iron as an electrode, and iron-air batteries were first studied in the 1960s. They were too heavy to make good transportation batteries. But this time, Chiang and team were looking at a battery that sat on the ground, so weight didn’t matter. Their priorities were cost and availability.

    “Iron is produced, mined, and processed on every continent,” Chiang says. “The Earth is one big ball of iron. We wouldn’t ever have to worry about even the most ambitious projections of how much storage that the world might use by mid-century.” If Form ever moves into the residential market, “it’ll be the safest battery you’ve ever parked at your house,” Chiang laughs. “Just iron, air, and water.”

    Scientists call it reversible rusting. While discharging, the battery takes in oxygen and converts iron to rust. Applying an electrical current converts the rusty pellets back to iron, and the battery “breathes out” oxygen as it charges. “In chemical terms, you have iron, and it becomes iron hydroxide,” Chiang says. “That means electrons were extracted. You get those electrons to go through the external circuit, and now you have a battery.”

    Form Energy’s battery modules are approximately the size of a washer-and-dryer unit. They are stacked in 40-foot containers, and several containers are electrically connected with power conversion systems to build storage plants that can cover several acres.

    The right place at the right time

    The modules don’t look or act like anything utilities have contracted for before.

    That’s one of Form’s key challenges. “There is not widespread knowledge of needing these new tools for decarbonized grids,” Ferrara says. “That’s not the way utilities have typically planned. They’re looking at all the tools in the toolkit that exist today, which may not contemplate a multi-day energy storage asset.”

    Form Energy’s customers are largely traditional power companies seeking to expand their portfolios of renewable electricity. Some are in the process of decommissioning coal plants and shifting to renewables.

    Ferrara’s research pinpointing the need for very low-cost multi-day storage provides key data for power suppliers seeking to determine the most cost-effective way to integrate more renewable energy.

    Using the same modeling techniques, Ferrara and team show potential customers how the technology fits in with their existing system, how it competes with other technologies, and how, in some cases, it can operate synergistically with other storage technologies.

    “They may need a portfolio of storage technologies to fully balance renewables on different timescales of intermittency,” he says. But other than the technology developed at Form, “there isn’t much out there, certainly not within the cost entitlement of what we’re bringing to market.”  Thanks to Chiang and Jaramillo’s chance encounter in Houston, Form has a several-year lead on other companies working to address this challenge. 

    In June 2023, Form Energy closed its biggest deal to date for a single project: Georgia Power’s order for a 15-megawatt/1,500-megawatt-hour system. That order brings Form’s total amount of energy storage under contracts with utility customers to 40 megawatts/4 gigawatt-hours. To meet the demand, Form is building a new commercial-scale battery manufacturing facility in West Virginia.

    The fact that Form Energy is creating jobs in an area that lost more than 10,000 steel jobs over the past decade is not lost on Chiang. “And these new jobs are in clean tech. It’s super exciting to me personally to be doing something that benefits communities outside of our traditional technology centers.

    “This is the right time for so many reasons,” Chiang says. He says he and his Form Energy co-founders feel “tremendous urgency to get these batteries out into the world.”

    This article appears in the Winter 2024 issue of Energy Futures, the magazine of the MIT Energy Initiative. More

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    Moving past the Iron Age

    MIT graduate student Sydney Rose Johnson has never seen the steel mills in central India. She’s never toured the American Midwest’s hulking steel plants or the mini mills dotting the Mississippi River. But in the past year, she’s become more familiar with steel production than she ever imagined.

    A fourth-year dual degree MBA and PhD candidate in chemical engineering and a graduate research assistant with the MIT Energy Initiative (MITEI) as well as a 2022-23 Shell Energy Fellow, Johnson looks at ways to reduce carbon dioxide (CO2) emissions generated by industrial processes in hard-to-abate industries. Those include steel.

    Almost every aspect of infrastructure and transportation — buildings, bridges, cars, trains, mass transit — contains steel. The manufacture of steel hasn’t changed much since the Iron Age, with some steel plants in the United States and India operating almost continually for more than a century, their massive blast furnaces re-lined periodically with carbon and graphite to keep them going.

    According to the World Economic Forum, steel demand is projected to increase 30 percent by 2050, spurred in part by population growth and economic development in China, India, Africa, and Southeast Asia.

    The steel industry is among the three biggest producers of CO2 worldwide. Every ton of steel produced in 2020 emitted, on average, 1.89 tons of CO2 into the atmosphere — around 8 percent of global CO2 emissions, according to the World Steel Association.

    A combination of technical strategies and financial investments, Johnson notes, will be needed to wrestle that 8 percent figure down to something more planet-friendly.

    Johnson’s thesis focuses on modeling and analyzing ways to decarbonize steel. Using data mined from academic and industry sources, she builds models to calculate emissions, costs, and energy consumption for plant-level production.

    “I optimize steel production pathways using emission goals, industry commitments, and cost,” she says. Based on the projected growth of India’s steel industry, she applies this approach to case studies that predict outcomes for some of the country’s thousand-plus factories, which together have a production capacity of 154 million metric tons of steel. For the United States, she looks at the effect of Inflation Reduction Act (IRA) credits. The 2022 IRA provides incentives that could accelerate the steel industry’s efforts to minimize its carbon emissions.

    Johnson compares emissions and costs across different production pathways, asking questions such as: “If we start today, what would a cost-optimal production scenario look like years from now? How would it change if we added in credits? What would have to happen to cut 2005 levels of emissions in half by 2030?”

    “My goal is to gain an understanding of how current and emerging decarbonization strategies will be integrated into the industry,” Johnson says.

    Grappling with industrial problems

    Growing up in Marietta, Georgia, outside Atlanta, the closest she ever came to a plant of any kind was through her father, a chemical engineer working in logistics and procuring steel for an aerospace company, and during high school, when she spent a semester working alongside chemical engineers tweaking the pH of an anti-foaming agent.

    At Kennesaw Mountain High School, a STEM magnet program in Cobb County, students devote an entire semester of their senior year to an internship and research project.

    Johnson chose to work at Kemira Chemicals, which develops chemical solutions for water-intensive industries with a focus on pulp and paper, water treatment, and energy systems.

    “My goal was to understand why a polymer product was falling out of suspension — essentially, why it was less stable,” she recalls. She learned how to formulate a lab-scale version of the product and conduct tests to measure its viscosity and acidity. Comparing the lab-scale and regular product results revealed that acidity was an important factor. “Through conversations with my mentor, I learned this was connected with the holding conditions, which led to the product being oxidized,” she says. With the anti-foaming agent’s problem identified, steps could be taken to fix it.

    “I learned how to apply problem-solving. I got to learn more about working in an industrial environment by connecting with the team in quality control as well as with R&D and chemical engineers at the plant site,” Johnson says. “This experience confirmed I wanted to pursue engineering in college.”

    As an undergraduate at Stanford University, she learned about the different fields — biotechnology, environmental science, electrochemistry, and energy, among others — open to chemical engineers. “It seemed like a very diverse field and application range,” she says. “I was just so intrigued by the different things I saw people doing and all these different sets of issues.”

    Turning up the heat

    At MIT, she turned her attention to how certain industries can offset their detrimental effects on climate.

    “I’m interested in the impact of technology on global communities, the environment, and policy. Energy applications affect every field. My goal as a chemical engineer is to have a broad perspective on problem-solving and to find solutions that benefit as many people, especially those under-resourced, as possible,” says Johnson, who has served on the MIT Chemical Engineering Graduate Student Advisory Board, the MIT Energy and Climate Club, and is involved with diversity and inclusion initiatives.

    The steel industry, Johnson acknowledges, is not what she first imagined when she saw herself working toward mitigating climate change.

    “But now, understanding the role the material has in infrastructure development, combined with its heavy use of coal, has illuminated how the sector, along with other hard-to-abate industries, is important in the climate change conversation,” Johnson says.

    Despite the advanced age of many steel mills, some are quite energy-efficient, she notes. Yet these operations, which produce heat upwards of 3,000 degrees Fahrenheit, are still emission-intensive.

    Steel is made from iron ore, a mixture of iron, oxygen, and other minerals found on virtually every continent, with Brazil and Australia alone exporting millions of metric tons per year. Commonly based on a process dating back to the 19th century, iron is extracted from the ore through smelting — heating the ore with blast furnaces until the metal becomes spongy and its chemical components begin to break down.

    A reducing agent is needed to release the oxygen trapped in the ore, transforming it from its raw form to pure iron. That’s where most emissions come from, Johnson notes.

    “We want to reduce emissions, and we want to make a cleaner and safer environment for everyone,” she says. “It’s not just the CO2 emissions. It’s also sometimes NOx and SOx [nitrogen oxides and sulfur oxides] and air pollution particulate matter at some of these production facilities that can affect people as well.”

    In 2020, the International Energy Agency released a roadmap exploring potential technologies and strategies that would make the iron and steel sector more compatible with the agency’s vision of increased sustainability. Emission reductions can be accomplished with more modern technology, the agency suggests, or by substituting the fuels producing the immense heat needed to process ore. Traditionally, the fuels used for iron reduction have been coal and natural gas. Alternative fuels include clean hydrogen, electricity, and biomass.

    Using the MITEI Sustainable Energy System Analysis Modeling Environment (SESAME), Johnson analyzes various decarbonization strategies. She considers options such as switching fuel for furnaces to hydrogen with a little bit of natural gas or adding carbon-capture devices. The models demonstrate how effective these tactics are likely to be. The answers aren’t always encouraging.

    “Upstream emissions can determine how effective the strategies are,” Johnson says. Charcoal derived from forestry biomass seemed to be a promising alternative fuel, but her models showed that processing the charcoal for use in the blast furnace limited its effectiveness in negating emissions.

    Despite the challenges, “there are definitely ways of moving forward,” Johnson says. “It’s been an intriguing journey in terms of understanding where the industry is at. There’s still a long way to go, but it’s doable.”

    Johnson is heartened by the steel industry’s efforts to recycle scrap into new steel products and incorporate more emission-friendly technologies and practices, some of which result in significantly lower CO2 emissions than conventional production.

    A major issue is that low-carbon steel can be more than 50 percent more costly than conventionally produced steel. “There are costs associated with making the transition, but in the context of the environmental implications, I think it’s well worth it to adopt these technologies,” she says.

    After graduation, Johnson plans to continue to work in the energy field. “I definitely want to use a combination of engineering knowledge and business knowledge to work toward mitigating climate change, potentially in the startup space with clean technology or even in a policy context,” she says. “I’m interested in connecting the private and public sectors to implement measures for improving our environment and benefiting as many people as possible.” More

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    Explained: Carbon credits

    One of the most contentious issues faced at the 28th Conference of Parties (COP28) on climate change last December was a proposal for a U.N.-sanctioned market for trading carbon credits. Such a mechanism would allow nations and industries making slow progress in reducing their own carbon emissions to pay others to take emissions-reducing measures, such as improving energy efficiency or protecting forests.

    Such trading systems have already grown to a multibillion-dollar market despite a lack of clear international regulations to define and monitor the claimed emissions reductions. During weeks of feverish negotiations, some nations, including the U.S., advocated for a somewhat looser approach to regulations in the interests of getting a system in place quickly. Others, including the European Union, advocated much tighter regulation, in light of a history of questionable or even counterproductive projects of this kind in the past. In the end, no agreement was reached on the subject, which will be revisited at a later meeting.

    The concept seems simple enough: Offset emissions in one place by preventing or capturing an equal amount of emissions elsewhere. But implementing that idea has turned out to be far more complex and fraught with problems than many expected.

    For example, projects that aim to preserve a section of forest — which can remove carbon dioxide from the air and sequester it in the soil — face numerous issues. Will the preservation of one parcel just lead to the clearcutting of an adjacent parcel? Would the preserved land have been left uncut anyway? And what if it ends up being destroyed by wildfire, drought, or insect infestation — all of which are expected to become more likely with climate change?

    Similarly, projects that aim to capture carbon dioxide emissions and inject them into the ground are sometimes used to justify increasing the production of petroleum or natural gas, negating the intended climate mitigation of the process.

    Several experts at MIT now say that the system could be effective, at least in certain circumstances, but it must be thoroughly evaluated and regulated.

    Carbon removal, natural or mechanical

    Sergey Paltsev, deputy director of MIT’s Joint Program on the Science and Policy of Global Change, co-led a study and workshop last year that included policymakers, industry representatives, and researchers. They focused on one kind of carbon offsets, those based on natural climate solutions — restoration or preservation of natural systems that not only sequester carbon but also provide other benefits, such as greater biodiversity. “We find a lot of confusion and misperceptions and misinformation, even about how you define the term carbon credit or offset,” he says.

    He points out that there has been a lot of criticism of the whole idea of carbon offsets, “and that criticism is well-placed. I think that’s a very healthy conversation, to clarify what makes sense and what doesn’t make sense. What are the real actions versus what is greenwashing?”

    He says that government-mandated and managed carbon trading programs in some places, including British Columbia and parts of Europe, have been somewhat effective because they have clear standards in place, whereas unregulated carbon credit systems have often been abused.

    Charles Harvey, an MIT professor of civil and environmental engineering, should know, having been actively involved in both sides of the issue over the last two decades. He co-founded a company in 2008 that was the first private U.S. company to attempt to remove carbon dioxide from emissions on a commercial scale, a process called carbon capture and sequestration, or CCS. Such projects have been a major recipient of federal subsidies aimed at combatting climate change, but Harvey now says these are largely a waste of money and in most cases do not achieve their stated objective.

    In fact, he says that according to industry sources, as of 2021 more than 90 percent of CCS projects in the U.S. have been used for the production of more fossil fuels — oil and natural gas. Here’s how it works: Natural gas wells often produce methane mixed with carbon dioxide, which must be removed to produce a marketable natural gas. This carbon dioxide is then injected into oil wells to stimulate more production. So, the net effect is the creation of more total greenhouse gas emissions rather than less, explains Harvey, who recently received a grant from the Rockefeller Foundation to explore CCS projects and whether they can be made to contribute to true emissions reductions.

    What went wrong with the ambitious startup CCS company Harvey co-founded? “What happened is that the prices of renewables and energy storage are now incredibly cheap,” he says. “It makes no sense to do this, ever, on power plants because honestly, fossil fuel power plants don’t even really make economic sense anymore.”

    Where does Harvey see potential for carbon credits to work? One possibility is the preservation or restoration of tropical peatlands, which he has received another grant to study. These are vast areas of permanently waterlogged land in which dead plant matter —and the carbon it contains — remains in place because the water prevents the normal decomposition processes that would otherwise release the stored carbon back into the air.

    While it is virtually impossible to quantify the amount of carbon stored in the soil of forest or farmland, in peatlands that’s easy to do because essentially all of the submerged material is carbon-based. Simply measuring changes in the elevation of such land, which can be done remotely by plane or satellite, gives a precise measure of how much carbon has been stored or released. When a patch of peat forest that has been clear-cut to build plantations or roads is reforested, the amount of carbon emissions that were prevented can be measured accurately.

    Because of that potential for accurate documentation, protecting or restoring peat bogs can also be a good way to achieve meaningful offsets for carbon emissions elsewhere, Harvey says. Rewetting a previously drained peat forest can immediately counteract the release of its stored carbon and can keep it there as long as it is not drained again — something that can be verified using satellite data.

    Paltsev adds that while such nature-based systems for countering carbon emissions can be a key component of addressing climate change, especially in very difficult-to-decarbonize industries such as aviation, carbon credits for such programs “shouldn’t be a replacement for our efforts at emissions reduction. It should be in addition.”

    Criteria for meaningful offsets

    John Sterman, the Jay W. Forrester Professor of Management at the MIT Sloan School of Management, has published a set of criteria for evaluating proposed carbon offset plans to make sure they would provide the benefits they claim. At present, “there’s no regulation, there’s no oversight” for carbon offsets, he says. “There have been many scandals over this.”

    For example, one company was providing what it claimed was certification for carbon offset projects but was found to have such lax standards that the claimed offsets were often not real. For example, there were multiple claims to protect the same piece of forest and claims to protect land that was already legally protected.

    Sterman’s proposed set of criteria goes by the acronym AVID+. “It stands for four principles that you have to meet in order for your offset to be legitimate: It has to be additional, verifiable, immediate, and durable,” he says. “And then I call it AVID+,” he adds, the “plus” being for plans that have additional benefits as well, such as improving health, creating jobs, or helping historically disadvantaged communities.

    Offsets can be useful, he says, for addressing especially hard-to-abate industries such as steel or cement manufacturing, or aviation. But it is essential to meet all four of the criteria, or else real emissions are not really being offset. For example, planting trees today, while often a good thing to do, would take decades to offset emissions going into the atmosphere now, where they may persist for centuries — so that fails to meet the “immediate” requirement.

    And protecting existing forests, while also desirable, is very hard to prove as being additional, because “that requires a counterfactual that you can never observe,” he says. “That’s where a lot of squirrely accounting and a lot of fraud comes in, because how do you know that the forest would have been cut down but for the offset?” In one well-documented case, he points out, a company tried to sell carbon offsets for a section of forest that was already an established nature preserve.

    Are there offsets that can meet all the criteria and provide real benefits in helping to address climate change? Yes, Sterman and Harvey say, but they need to be evaluated carefully.

    “My favorite example,” Sterman says, “is doing deep energy retrofits and putting solar panels on low-income housing.” These measures can help address the so-called landlord-tenant problem: If tenants typically pay the utility bills, landlords have little incentive to pay for efficiency improvements, and the tenants don’t have the capital to make such improvements on their own. “Policies that would make this possible are pretty good candidates for legitimate offsets, because they are additional — low-income households can’t afford to do it without assistance, so it’s not going to happen without a program. It’s verifiable, because you’ve got the utility bills pre and post.” They are also quite immediate, typically taking only a year or so to implement, and “they’re pretty durable,” he says.

    Another example is a recent plan in Alaska that allows cruise ships to offset the emissions caused by their trips by paying into a fund that provides subsidies for Alaskan citizens to install heat pumps in their homes, thus preventing emissions from wood or fossil fuel heating systems. “I think this is a pretty good candidate to meet the criteria, certainly a lot better than much of what’s being done today,” Sterman says.

    But eventually, what is really needed, the researchers agree, are real, enforceable standards. After COP28, carbon offsets are still allowed, Sterman says, “but there is still no widely accepted mandatory regulation. We’re still in the wild West.”

    Paltsev nevertheless sees reasons for optimism about nature-based carbon offset systems. For example, he says the aviation industry has recently agreed to implement a set of standards for offsetting their emissions, known as CORSIA, for carbon offsetting and reduction scheme for international aviation. “It’s a point for optimism,” he says, “because they issued very tough guidelines as to what projects are eligible and what projects are not.”

    He adds, “There is a solution if you want to find a good solution. It is doable, when there is a will and there is the need.” More