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    Unlocking the hidden power of boiling — for energy, space, and beyond

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    Most people take boiling water for granted. For Associate Professor Matteo Bucci, uncovering the physics behind boiling has been a decade-long journey filled with unexpected challenges and new insights.The seemingly simple phenomenon is extremely hard to study in complex systems like nuclear reactors, and yet it sits at the core of a wide range of important industrial processes. Unlocking its secrets could thus enable advances in efficient energy production, electronics cooling, water desalination, medical diagnostics, and more.“Boiling is important for applications way beyond nuclear,” says Bucci, who earned tenure at MIT in July. “Boiling is used in 80 percent of the power plants that produce electricity. My research has implications for space propulsion, energy storage, electronics, and the increasingly important task of cooling computers.”Bucci’s lab has developed new experimental techniques to shed light on a wide range of boiling and heat transfer phenomena that have limited energy projects for decades. Chief among those is a problem caused by bubbles forming so quickly they create a band of vapor across a surface that prevents further heat transfer. In 2023, Bucci and collaborators developed a unifying principle governing the problem, known as the boiling crisis, which could enable more efficient nuclear reactors and prevent catastrophic failures.For Bucci, each bout of progress brings new possibilities — and new questions to answer.“What’s the best paper?” Bucci asks. “The best paper is the next one. I think Alfred Hitchcock used to say it doesn’t matter how good your last movie was. If your next one is poor, people won’t remember it. I always tell my students that our next paper should always be better than the last. It’s a continuous journey of improvement.”From engineering to bubblesThe Italian village where Bucci grew up had a population of about 1,000 during his childhood. He gained mechanical skills by working in his father’s machine shop and by taking apart and reassembling appliances like washing machines and air conditioners to see what was inside. He also gained a passion for cycling, competing in the sport until he attended the University of Pisa for undergraduate and graduate studies.In college, Bucci was fascinated with matter and the origins of life, but he also liked building things, so when it came time to pick between physics and engineering, he decided nuclear engineering was a good middle ground.“I have a passion for construction and for understanding how things are made,” Bucci says. “Nuclear engineering was a very unlikely but obvious choice. It was unlikely because in Italy, nuclear was already out of the energy landscape, so there were very few of us. At the same time, there were a combination of intellectual and practical challenges, which is what I like.”For his PhD, Bucci went to France, where he met his wife, and went on to work at a French national lab. One day his department head asked him to work on a problem in nuclear reactor safety known as transient boiling. To solve it, he wanted to use a method for making measurements pioneered by MIT Professor Jacopo Buongiorno, so he received grant money to become a visiting scientist at MIT in 2013. He’s been studying boiling at MIT ever since.Today Bucci’s lab is developing new diagnostic techniques to study boiling and heat transfer along with new materials and coatings that could make heat transfer more efficient. The work has given researchers an unprecedented view into the conditions inside a nuclear reactor.“The diagnostics we’ve developed can collect the equivalent of 20 years of experimental work in a one-day experiment,” Bucci says.That data, in turn, led Bucci to a remarkably simple model describing the boiling crisis.“The effectiveness of the boiling process on the surface of nuclear reactor cladding determines the efficiency and the safety of the reactor,” Bucci explains. “It’s like a car that you want to accelerate, but there is an upper limit. For a nuclear reactor, that upper limit is dictated by boiling heat transfer, so we are interested in understanding what that upper limit is and how we can overcome it to enhance the reactor performance.”Another particularly impactful area of research for Bucci is two-phase immersion cooling, a process wherein hot server parts bring liquid to boil, then the resulting vapor condenses on a heat exchanger above to create a constant, passive cycle of cooling.“It keeps chips cold with minimal waste of energy, significantly reducing the electricity consumption and carbon dioxide emissions of data centers,” Bucci explains. “Data centers emit as much CO2 as the entire aviation industry. By 2040, they will account for over 10 percent of emissions.”Supporting studentsBucci says working with students is the most rewarding part of his job. “They have such great passion and competence. It’s motivating to work with people who have the same passion as you.”“My students have no fear to explore new ideas,” Bucci adds. “They almost never stop in front of an obstacle — sometimes to the point where you have to slow them down and put them back on track.”In running the Red Lab in the Department of Nuclear Science and Engineering, Bucci tries to give students independence as well as support.“We’re not educating students, we’re educating future researchers,” Bucci says. “I think the most important part of our work is to not only provide the tools, but also to give the confidence and the self-starting attitude to fix problems. That can be business problems, problems with experiments, problems with your lab mates.”Some of the more unique experiments Bucci’s students do require them to gather measurements while free falling in an airplane to achieve zero gravity.“Space research is the big fantasy of all the kids,” says Bucci, who joins students in the experiments about twice a year. “It’s very fun and inspiring research for students. Zero g gives you a new perspective on life.”Applying AIBucci is also excited about incorporating artificial intelligence into his field. In 2023, he was a co-recipient of a multi-university research initiative (MURI) project in thermal science dedicated solely to machine learning. In a nod to the promise AI holds in his field, Bucci also recently founded a journal called AI Thermal Fluids to feature AI-driven research advances.“Our community doesn’t have a home for people that want to develop machine-learning techniques,” Bucci says. “We wanted to create an avenue for people in computer science and thermal science to work together to make progress. I think we really need to bring computer scientists into our community to speed this process up.”Bucci also believes AI can be used to process huge reams of data gathered using the new experimental techniques he’s developed as well as to model phenomena researchers can’t yet study.“It’s possible that AI will give us the opportunity to understand things that cannot be observed, or at least guide us in the dark as we try to find the root causes of many problems,” Bucci says. More

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      Helping students bring about decarbonization, from benchtop to global energy marketplace

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      MIT students are adept at producing research and innovations at the cutting edge of their fields. But addressing a problem as large as climate change requires understanding the world’s energy landscape, as well as the ways energy technologies evolve over time.Since 2010, the course IDS.521/IDS.065 (Energy Systems for Climate Change Mitigation) has equipped students with the skills they need to evaluate the various energy decarbonization pathways available to the world. The work is designed to help them maximize their impact on the world’s emissions by making better decisions along their respective career paths.“The question guiding my teaching and research is how do we solve big societal challenges with technology, and how can we be more deliberate in developing and supporting technologies to get us there?” says Professor Jessika Trancik, who started the course to help fill a gap in knowledge about the ways technologies evolve and scale over time.Since its inception in 2010, the course has attracted graduate students from across MIT’s five schools. The course has also recently opened to undergraduate students and been adapted to an online course for professionals.Class sessions alternate between lectures and student discussions that lead up to semester-long projects in which groups of students explore specific strategies and technologies for reducing global emissions. This year’s projects span several topics, including how quickly transmission infrastructure is expanding, the relationship between carbon emissions and human development, and how to decarbonize the production of key chemicals.The curriculum is designed to help students identify the most promising ways to mitigate climate change whether they plan to be scientists, engineers, policymakers, investors, urban planners, or just more informed citizens.“We’re coming at this issue from both sides,” explains Trancik, who is part of MIT’s Institute for Data, Systems, and Society. “Engineers are used to designing a technology to work as well as possible here and now, but not always thinking over a longer time horizon about a technology evolving and succeeding in the global marketplace. On the flip side, for students at the macro level, often studies in policy and economics of technological change don’t fully account for the physical and engineering constraints of rates of improvement. But all of that information allows you to make better decisions.”Bridging the gapAs a young researcher working on low-carbon polymers and electrode materials for solar cells, Trancik always wondered how the materials she worked on would scale in the real world. They might achieve promising performance benchmarks in the lab, but would they actually make a difference in mitigating climate change? Later, she began focusing increasingly on developing methods for predicting how technologies might evolve.“I’ve always been interested in both the macro and the micro, or even nano, scales,” Trancik says. “I wanted to know how to bridge these new technologies we’re working on with the big picture of where we want to go.”Trancik’ described her technology-grounded approach to decarbonization in a paper that formed the basis for IDS.065. In the paper, she presented a way to evaluate energy technologies against climate-change mitigation goals while focusing on the technology’s evolution.“That was a departure from previous approaches, which said, given these technologies with fixed characteristics and assumptions about their rates of change, how do I choose the best combination?” Trancik explains. “Instead we asked: Given a goal, how do we develop the best technologies to meet that goal? That inverts the problem in a way that’s useful to engineers developing these technologies, but also to policymakers and investors that want to use the evolution of technologies as a tool for achieving their objectives.”This past semester, the class took place every Tuesday and Thursday in a classroom on the first floor of the Stata Center. Students regularly led discussions where they reflected on the week’s readings and offered their own insights.“Students always share their takeaways and get to ask open questions of the class,” says Megan Herrington, a PhD candidate in the Department of Chemical Engineering. “It helps you understand the readings on a deeper level because people with different backgrounds get to share their perspectives on the same questions and problems. Everybody comes to class with their own lens, and the class is set up to highlight those differences.”The semester begins with an overview of climate science, the origins of emissions reductions goals, and technology’s role in achieving those goals. Students then learn how to evaluate technologies against decarbonization goals.But technologies aren’t static, and neither is the world. Later lessons help students account for the change of technologies over time, identifying the mechanisms for that change and even forecasting rates of change.Students also learn about the role of government policy. This year, Trancik shared her experience traveling to the COP29 United Nations Climate Change Conference.“It’s not just about technology,” Trancik says. “It’s also about the behaviors that we engage in and the choices we make. But technology plays a major role in determining what set of choices we can make.”From the classroom to the worldStudents in the class say it has given them a new perspective on climate change mitigation.“I have really enjoyed getting to see beyond the research people are doing at the benchtop,” says Herrington. “It’s interesting to see how certain materials or technologies that aren’t scalable yet may fit into a larger transformation in energy delivery and consumption. It’s also been interesting to pull back the curtain on energy systems analysis to understand where the metrics we cite in energy-related research originate from, and to anticipate trajectories of emerging technologies.”Onur Talu, a first-year master’s student in the Technology and Policy Program, says the class has made him more hopeful.“I came into this fairly pessimistic about the climate,” says Talu, who has worked for clean technology startups in the past. “This class has taught me different ways to look at the problem of climate change mitigation and developing renewable technologies. It’s also helped put into perspective how much we’ve accomplished so far.”Several student projects from the class over the years have been developed into papers published in peer-reviewed journals. They have also been turned into tools, like carboncounter.com, which plots the emissions and costs of cars and has been featured in The New York Times.Former class students have also launched startups; Joel Jean SM ’13, PhD ’17, for example, started Swift Solar. Others have drawn on the course material to develop impactful careers in government and academia, such as Patrick Brown PhD ’16 at the National Renewable Energy Laboratory and Leah Stokes SM ’15, PhD ’15 at the University of California at Santa Barbara.Overall, students say the course helps them take a more informed approach to applying their skills toward addressing climate change.“It’s not enough to just know how bad climate change could be,” says Yu Tong, a first-year master’s student in civil and environmental engineering. “It’s also important to understand how technology can work to mitigate climate change from both a technological and market perspective. It’s about employing technology to solve these issues rather than just working in a vacuum.” More

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      MIT spinout Commonwealth Fusion Systems unveils plans for the world’s first fusion power plant

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      America is one step closer to tapping into a new and potentially limitless clean energy source today, with the announcement from MIT spinout Commonwealth Fusion Systems (CFS) that it plans to build the world’s first grid-scale fusion power plant in Chesterfield County, Virginia.The announcement is the latest milestone for the company, which has made groundbreaking progress toward harnessing fusion — the reaction that powers the sun — since its founders first conceived of their approach in an MIT classroom in 2012. CFS is now commercializing a suite of advanced technologies developed in MIT research labs.“This moment exemplifies the power of MIT’s mission, which is to create knowledge that serves the nation and the world, whether via the classroom, the lab, or out in communities,” MIT Vice President for Research Ian Waitz says. “From student coursework 12 years ago to today’s announcement of the siting in Virginia of the world’s first fusion power plant, progress has been amazingly rapid. At the same time, we owe this progress to over 65 years of sustained investment by the U.S. federal government in basic science and energy research.”The new fusion power plant, named ARC, is expected to come online in the early 2030s and generate about 400 megawatts of clean, carbon-free electricity — enough energy to power large industrial sites or about 150,000 homes.The plant will be built at the James River Industrial Park outside of Richmond through a nonfinancial collaboration with Dominion Energy Virginia, which will provide development and technical expertise along with leasing rights for the site. CFS will independently finance, build, own, and operate the power plant.The plant will support Virginia’s economic and clean energy goals by generating what is expected to be billions of dollars in economic development and hundreds of jobs during its construction and long-term operation.More broadly, ARC will position the U.S. to lead the world in harnessing a new form of safe and reliable energy that could prove critical for economic prosperity and national security, including for meeting increasing electricity demands driven by needs like artificial intelligence.“This will be a watershed moment for fusion,” says CFS co-founder Dennis Whyte, the Hitachi America Professor of Engineering at MIT. “It sets the pace in the race toward commercial fusion power plants. The ambition is to build thousands of these power plants and to change the world.”Fusion can generate energy from abundant fuels like hydrogen and lithium isotopes, which can be sourced from seawater, and leave behind no emissions or toxic waste. However, harnessing fusion in a way that produces more power than it takes in has proven difficult because of the high temperatures needed to create and maintain the fusion reaction. Over the course of decades, scientists and engineers have worked to make the dream of fusion power plants a reality.In 2012, teaching the MIT class 22.63 (Principles of Fusion Engineering), Whyte challenged a group of graduate students to design a fusion device that would use a new kind of superconducting magnet to confine the plasma used in the reaction. It turned out the magnets enabled a more compact and economic reactor design. When Whyte reviewed his students’ work, he realized that could mean a new development path for fusion.Since then, a huge amount of capital and expertise has rushed into the once fledgling fusion industry. Today there are dozens of private fusion companies around the world racing to develop the first net-energy fusion power plants, many utilizing the new superconducting magnets. CFS, which Whyte founded with several students from his class, has attracted more than $2 billion in funding.“It all started with that class, where our ideas kept evolving as we challenged the standard assumptions that came with fusion,” Whyte says. “We had this new superconducting technology, so much of the common wisdom was no longer valid. It was a perfect forum for students, who can challenge the status quo.”Since the company’s founding in 2017, it has collaborated with researchers in MIT’s Plasma Science and Fusion Center (PFSC) on a range of initiatives, from validating the underlying plasma physics for the first demonstration machine to breaking records with a new kind of magnet to be used in commercial fusion power plants. Each piece of progress moves the U.S. closer to harnessing a revolutionary new energy source.CFS is currently completing development of its fusion demonstration machine, SPARC, at its headquarters in Devens, Massachusetts. SPARC is expected to produce its first plasma in 2026 and net fusion energy shortly after, demonstrating for the first time a commercially relevant design that will produce more power than it consumes. SPARC will pave the way for ARC, which is expected to deliver power to the grid in the early 2030s.“There’s more challenging engineering and science to be done in this field, and we’re very enthusiastic about the progress that CFS and the researchers on our campus are making on those problems,” Waitz says. “We’re in a ‘hockey stick’ moment in fusion energy, where things are moving incredibly quickly now. On the other hand, we can’t forget about the much longer part of that hockey stick, the sustained support for very complex, fundamental research that underlies great innovations. If we’re going to continue to lead the world in these cutting-edge technologies, continued investment in those areas will be crucial.” More

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      New climate chemistry model finds “non-negligible” impacts of potential hydrogen fuel leakage

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      As the world looks for ways to stop climate change, much discussion focuses on using hydrogen instead of fossil fuels, which emit climate-warming greenhouse gases (GHGs) when they’re burned. The idea is appealing. Burning hydrogen doesn’t emit GHGs to the atmosphere, and hydrogen is well-suited for a variety of uses, notably as a replacement for natural gas in industrial processes, power generation, and home heating.But while burning hydrogen won’t emit GHGs, any hydrogen that’s leaked from pipelines or storage or fueling facilities can indirectly cause climate change by affecting other compounds that are GHGs, including tropospheric ozone and methane, with methane impacts being the dominant effect. A much-cited 2022 modeling study analyzing hydrogen’s effects on chemical compounds in the atmosphere concluded that these climate impacts could be considerable. With funding from the MIT Energy Initiative’s Future Energy Systems Center, a team of MIT researchers took a more detailed look at the specific chemistry that poses the risks of using hydrogen as a fuel if it leaks.The researchers developed a model that tracks many more chemical reactions that may be affected by hydrogen and includes interactions among chemicals. Their open-access results, published Oct. 28 in Frontiers in Energy Research, showed that while the impact of leaked hydrogen on the climate wouldn’t be as large as the 2022 study predicted — and that it would be about a third of the impact of any natural gas that escapes today — leaked hydrogen will impact the climate. Leak prevention should therefore be a top priority as the hydrogen infrastructure is built, state the researchers.Hydrogen’s impact on the “detergent” that cleans our atmosphereGlobal three-dimensional climate-chemistry models using a large number of chemical reactions have also been used to evaluate hydrogen’s potential climate impacts, but results vary from one model to another, motivating the MIT study to analyze the chemistry. Most studies of the climate effects of using hydrogen consider only the GHGs that are emitted during the production of the hydrogen fuel. Different approaches may make “blue hydrogen” or “green hydrogen,” a label that relates to the GHGs emitted. Regardless of the process used to make the hydrogen, the fuel itself can threaten the climate. For widespread use, hydrogen will need to be transported, distributed, and stored — in short, there will be many opportunities for leakage. The question is, What happens to that leaked hydrogen when it reaches the atmosphere? The 2022 study predicting large climate impacts from leaked hydrogen was based on reactions between pairs of just four chemical compounds in the atmosphere. The results showed that the hydrogen would deplete a chemical species that atmospheric chemists call the “detergent of the atmosphere,” explains Candice Chen, a PhD candidate in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS). “It goes around zapping greenhouse gases, pollutants, all sorts of bad things in the atmosphere. So it’s cleaning our air.” Best of all, that detergent — the hydroxyl radical, abbreviated as OH — removes methane, which is an extremely potent GHG in the atmosphere. OH thus plays an important role in slowing the rate at which global temperatures rise. But any hydrogen leaked to the atmosphere would reduce the amount of OH available to clean up methane, so the concentration of methane would increase.However, chemical reactions among compounds in the atmosphere are notoriously complicated. While the 2022 study used a “four-equation model,” Chen and her colleagues — Susan Solomon, the Lee and Geraldine Martin Professor of Environmental Studies and Chemistry; and Kane Stone, a research scientist in EAPS — developed a model that includes 66 chemical reactions. Analyses using their 66-equation model showed that the four-equation system didn’t capture a critical feedback involving OH — a feedback that acts to protect the methane-removal process.Here’s how that feedback works: As the hydrogen decreases the concentration of OH, the cleanup of methane slows down, so the methane concentration increases. However, that methane undergoes chemical reactions that can produce new OH radicals. “So the methane that’s being produced can make more of the OH detergent,” says Chen. “There’s a small countering effect. Indirectly, the methane helps produce the thing that’s getting rid of it.” And, says Chen, that’s a key difference between their 66-equation model and the four-equation one. “The simple model uses a constant value for the production of OH, so it misses that key OH-production feedback,” she says.To explore the importance of including that feedback effect, the MIT researchers performed the following analysis: They assumed that a single pulse of hydrogen was injected into the atmosphere and predicted the change in methane concentration over the next 100 years, first using four-equation model and then using the 66-equation model. With the four-equation system, the additional methane concentration peaked at nearly 2 parts per billion (ppb); with the 66-equation system, it peaked at just over 1 ppb.Because the four-equation analysis assumes only that the injected hydrogen destroys the OH, the methane concentration increases unchecked for the first 10 years or so. In contrast, the 66-equation analysis goes one step further: the methane concentration does increase, but as the system re-equilibrates, more OH forms and removes methane. By not accounting for that feedback, the four-equation analysis overestimates the peak increase in methane due to the hydrogen pulse by about 85 percent. Spread over time, the simple model doubles the amount of methane that forms in response to the hydrogen pulse.Chen cautions that the point of their work is not to present their result as “a solid estimate” of the impact of hydrogen. Their analysis is based on a simple “box” model that represents global average conditions and assumes that all the chemical species present are well mixed. Thus, the species can vary over time — that is, they can be formed and destroyed — but any species that are present are always perfectly mixed. As a result, a box model does not account for the impact of, say, wind on the distribution of species. “The point we’re trying to make is that you can go too simple,” says Chen. “If you’re going simpler than what we’re representing, you will get further from the right answer.” She goes on to note, “The utility of a relatively simple model like ours is that all of the knobs and levers are very clear. That means you can explore the system and see what affects a value of interest.”Leaked hydrogen versus leaked natural gas: A climate comparisonBurning natural gas produces fewer GHG emissions than does burning coal or oil; but as with hydrogen, any natural gas that’s leaked from wells, pipelines, and processing facilities can have climate impacts, negating some of the perceived benefits of using natural gas in place of other fossil fuels. After all, natural gas consists largely of methane, the highly potent GHG in the atmosphere that’s cleaned up by the OH detergent. Given its potency, even small leaks of methane can have a large climate impact.So when thinking about replacing natural gas fuel — essentially methane — with hydrogen fuel, it’s important to consider how the climate impacts of the two fuels compare if and when they’re leaked. The usual way to compare the climate impacts of two chemicals is using a measure called the global warming potential, or GWP. The GWP combines two measures: the radiative forcing of a gas — that is, its heat-trapping ability — with its lifetime in the atmosphere. Since the lifetimes of gases differ widely, to compare the climate impacts of two gases, the convention is to relate the GWP of each one to the GWP of carbon dioxide. But hydrogen and methane leakage cause increases in methane, and that methane decays according to its lifetime. Chen and her colleagues therefore realized that an unconventional procedure would work: they could compare the impacts of the two leaked gases directly. What they found was that the climate impact of hydrogen is about three times less than that of methane (on a per mass basis). So switching from natural gas to hydrogen would not only eliminate combustion emissions, but also potentially reduce the climate effects, depending on how much leaks.Key takeawaysIn summary, Chen highlights some of what she views as the key findings of the study. First on her list is the following: “We show that a really simple four-equation system is not what should be used to project out the atmospheric response to more hydrogen leakages in the future.” The researchers believe that their 66-equation model is a good compromise for the number of chemical reactions to include. It generates estimates for the GWP of methane “pretty much in line with the lower end of the numbers that most other groups are getting using much more sophisticated climate chemistry models,” says Chen. And it’s sufficiently transparent to use in exploring various options for protecting the climate. Indeed, the MIT researchers plan to use their model to examine scenarios that involve replacing other fossil fuels with hydrogen to estimate the climate benefits of making the switch in coming decades.The study also demonstrates a valuable new way to compare the greenhouse effects of two gases. As long as their effects exist on similar time scales, a direct comparison is possible — and preferable to comparing each with carbon dioxide, which is extremely long-lived in the atmosphere. In this work, the direct comparison generates a simple look at the relative climate impacts of leaked hydrogen and leaked methane — valuable information to take into account when considering switching from natural gas to hydrogen.Finally, the researchers offer practical guidance for infrastructure development and use for both hydrogen and natural gas. Their analyses determine that hydrogen fuel itself has a “non-negligible” GWP, as does natural gas, which is mostly methane. Therefore, minimizing leakage of both fuels will be necessary to achieve net-zero carbon emissions by 2050, the goal set by both the European Commission and the U.S. Department of State. Their paper concludes, “If used nearly leak-free, hydrogen is an excellent option. Otherwise, hydrogen should only be a temporary step in the energy transition, or it must be used in tandem with carbon-removal steps [elsewhere] to counter its warming effects.” More

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      Transforming fusion from a scientific curiosity into a powerful clean energy source

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      If you’re looking for hard problems, building a nuclear fusion power plant is a pretty good place to start. Fusion — the process that powers the sun — has proven to be a difficult thing to recreate here on Earth despite decades of research.“There’s something very attractive to me about the magnitude of the fusion challenge,” Hartwig says. “It’s probably true of a lot of people at MIT. I’m driven to work on very hard problems. There’s something intrinsically satisfying about that battle. It’s part of the reason I’ve stayed in this field. We have to cross multiple frontiers of physics and engineering if we’re going to get fusion to work.”The problem got harder when, in Hartwig’s last year in graduate school, the Department of Energy announced plans to terminate funding for the Alcator C-Mod tokamak, a major fusion experiment in MIT’s Plasma Science and Fusion Center that Hartwig needed to do to graduate. Hartwig was able to finish his PhD, and the scare didn’t dissuade him from the field. In fact, he took an associate professor position at MIT in 2017 to keep working on fusion.“It was a pretty bleak time to take a faculty position in fusion energy, but I am a person who loves to find a vacuum,” says Hartwig, who is a newly tenured associate professor at MIT. “I adore a vacuum because there’s enormous opportunity in chaos.”Hartwig did have one very good reason for hope. In 2012, he had taken a class taught by Professor Dennis Whyte that challenged students to design and assess the economics of a nuclear fusion power plant that incorporated a new kind of high-temperature superconducting magnet. Hartwig says the magnets enable fusion reactors to be much smaller, cheaper, and faster.Whyte, Hartwig, and a few other members of the class started working nights and weekends to prove the reactors were feasible. In 2017, the group founded Commonwealth Fusion Systems (CFS) to build the world’s first commercial-scale fusion power plants.Over the next four years, Hartwig led a research project at MIT with CFS that further developed the magnet technology and scaled it to create a 20-Tesla superconducting magnet — a suitable size for a nuclear fusion power plant.The magnet and subsequent tests of its performance represented a turning point for the industry. Commonwealth Fusion Systems has since attracted more than $2 billion in investments to build its first reactors, while the fusion industry overall has exceeded $8 billion in private investment.The old joke in fusion is that the technology is always 30 years away. But fewer people are laughing these days.“The perspective in 2024 looks quite a bit different than it did in 2016, and a huge part of that is tied to the institutional capability of a place like MIT and the willingness of people here to accomplish big things,” Hartwig says.A path to the starsAs a child growing up in St. Louis, Hartwig was interested in sports and playing outside with friends but had little interest in physics. When he went to Boston University as an undergraduate, he studied biomedical engineering simply because his older brother had done it, so he thought he could get a job. But as he was introduced to tools for structural experiments and analysis, he found himself more interested in how the tools worked than what they could do.“That led me to physics, and physics ended up leading me to nuclear science, where I’m basically still doing applied physics,” Hartwig explains.Joining the field late in his undergraduate studies, Hartwig worked hard to get his physics degree on time. After graduation, he was burnt out, so he took two years off and raced his bicycle competitively while working in a bike shop.“There’s so much pressure on people in science and engineering to go straight through,” Hartwig says. “People say if you take time off, you won’t be able to get into graduate school, you won’t be able to get recommendation letters. I always tell my students, ‘It depends on the person.’ Everybody’s different, but it was a great period for me, and it really set me up to enter graduate school with a more mature mindset and to be more focused.”Hartwig returned to academia as a PhD student in MIT’s Department of Nuclear Science and Engineering in 2007. When his thesis advisor, Dennis Whyte, announced a course focused on designing nuclear fusion power plants, it caught Hartwig’s eye. The final projects showed a surprisingly promising path forward for a fusion field that had been stagnant for decades. The rest was history.“We started CFS with the idea that it would partner deeply with MIT and MIT’s Plasma Science and Fusion Center to leverage the infrastructure, expertise, people, and capabilities that we have MIT,” Hartwig says. “We had to start the company with the idea that it would be deeply partnered with MIT in an innovative way that hadn’t really been done before.”Guided by impactHartwig says the Department of Nuclear Science and Engineering, and the Plasma Science and Fusion Center in particular, have seen a huge influx in graduate student applications in recent years.“There’s so much demand, because people are excited again about the possibilities,” Hartwig says. “Instead of having fusion and a machine built in one or two generations, we’ll hopefully be learning how these things work in under a decade.”Hartwig’s research group is still testing CFS’ new magnets, but it is also partnering with other fusion companies in an effort to advance the field more broadly.Overall, when Hartwig looks back at his career, the thing he is most proud of is switching specialties every six years or so, from building equipment for his PhD to conducting fundamental experiments to designing reactors to building magnets.“It’s not that traditional in academia,” Hartwig says. “Where I’ve found success is coming into something new, bringing a naivety but also realism to a new field, and offering a different toolkit, a different approach, or a different idea about what can be done.”Now Hartwig is onto his next act, developing new ways to study materials for use in fusion and fission reactors.“I’m already interested in moving on to the next thing; the next field where I’m not a trained expert,” Hartwig says. “It’s about identifying where there’s stagnation in fusion and in technology, where innovation is not happening where we desperately need it, and bringing new ideas to that.” More

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      So you want to build a solar or wind farm? Here’s how to decide where.

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      Deciding where to build new solar or wind installations is often left up to individual developers or utilities, with limited overall coordination. But a new study shows that regional-level planning using fine-grained weather data, information about energy use, and energy system modeling can make a big difference in the design of such renewable power installations. This also leads to more efficient and economically viable operations.The findings show the benefits of coordinating the siting of solar farms, wind farms, and storage systems, taking into account local and temporal variations in wind, sunlight, and energy demand to maximize the utilization of renewable resources. This approach can reduce the need for sizable investments in storage, and thus the total system cost, while maximizing availability of clean power when it’s needed, the researchers found.The study, appearing today in the journal Cell Reports Sustainability, was co-authored by Liying Qiu and Rahman Khorramfar, postdocs in MIT’s Department of Civil and Environmental Engineering, and professors Saurabh Amin and Michael Howland.Qiu, the lead author, says that with the team’s new approach, “we can harness the resource complementarity, which means that renewable resources of different types, such as wind and solar, or different locations can compensate for each other in time and space. This potential for spatial complementarity to improve system design has not been emphasized and quantified in existing large-scale planning.”Such complementarity will become ever more important as variable renewable energy sources account for a greater proportion of power entering the grid, she says. By coordinating the peaks and valleys of production and demand more smoothly, she says, “we are actually trying to use the natural variability itself to address the variability.”Typically, in planning large-scale renewable energy installations, Qiu says, “some work on a country level, for example saying that 30 percent of energy should be wind and 20 percent solar. That’s very general.” For this study, the team looked at both weather data and energy system planning modeling on a scale of less than 10-kilometer (about 6-mile) resolution. “It’s a way of determining where should we, exactly, build each renewable energy plant, rather than just saying this city should have this many wind or solar farms,” she explains.To compile their data and enable high-resolution planning, the researchers relied on a variety of sources that had not previously been integrated. They used high-resolution meteorological data from the National Renewable Energy Laboratory, which is publicly available at 2-kilometer resolution but rarely used in a planning model at such a fine scale. These data were combined with an energy system model they developed to optimize siting at a sub-10-kilometer resolution. To get a sense of how the fine-scale data and model made a difference in different regions, they focused on three U.S. regions — New England, Texas, and California — analyzing up to 138,271 possible siting locations simultaneously for a single region.By comparing the results of siting based on a typical method vs. their high-resolution approach, the team showed that “resource complementarity really helps us reduce the system cost by aligning renewable power generation with demand,” which should translate directly to real-world decision-making, Qiu says. “If an individual developer wants to build a wind or solar farm and just goes to where there is the most wind or solar resource on average, it may not necessarily guarantee the best fit into a decarbonized energy system.”That’s because of the complex interactions between production and demand for electricity, as both vary hour by hour, and month by month as seasons change. “What we are trying to do is minimize the difference between the energy supply and demand rather than simply supplying as much renewable energy as possible,” Qiu says. “Sometimes your generation cannot be utilized by the system, while at other times, you don’t have enough to match the demand.”In New England, for example, the new analysis shows there should be more wind farms in locations where there is a strong wind resource during the night, when solar energy is unavailable. Some locations tend to be windier at night, while others tend to have more wind during the day.These insights were revealed through the integration of high-resolution weather data and energy system optimization used by the researchers. When planning with lower resolution weather data, which was generated at a 30-kilometer resolution globally and is more commonly used in energy system planning, there was much less complementarity among renewable power plants. Consequently, the total system cost was much higher. The complementarity between wind and solar farms was enhanced by the high-resolution modeling due to improved representation of renewable resource variability.The researchers say their framework is very flexible and can be easily adapted to any region to account for the local geophysical and other conditions. In Texas, for example, peak winds in the west occur in the morning, while along the south coast they occur in the afternoon, so the two naturally complement each other.Khorramfar says that this work “highlights the importance of data-driven decision making in energy planning.” The work shows that using such high-resolution data coupled with carefully formulated energy planning model “can drive the system cost down, and ultimately offer more cost-effective pathways for energy transition.”One thing that was surprising about the findings, says Amin, who is a principal investigator in the MIT Laboratory of Information and Data Systems, is how significant the gains were from analyzing relatively short-term variations in inputs and outputs that take place in a 24-hour period. “The kind of cost-saving potential by trying to harness complementarity within a day was not something that one would have expected before this study,” he says.In addition, Amin says, it was also surprising how much this kind of modeling could reduce the need for storage as part of these energy systems. “This study shows that there is actually a hidden cost-saving potential in exploiting local patterns in weather, that can result in a monetary reduction in storage cost.”The system-level analysis and planning suggested by this study, Howland says, “changes how we think about where we site renewable power plants and how we design those renewable plants, so that they maximally serve the energy grid. It has to go beyond just driving down the cost of energy of individual wind or solar farms. And these new insights can only be realized if we continue collaborating across traditional research boundaries, by integrating expertise in fluid dynamics, atmospheric science, and energy engineering.”The research was supported by the MIT Climate and Sustainability Consortium and MIT Climate Grand Challenges. More

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      Is there enough land on Earth to fight climate change and feed the world?

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      Capping global warming at 1.5 degrees Celsius is a tall order. Achieving that goal will not only require a massive reduction in greenhouse gas emissions from human activities, but also a substantial reallocation of land to support that effort and sustain the biosphere, including humans. More land will be needed to accommodate a growing demand for bioenergy and nature-based carbon sequestration while ensuring sufficient acreage for food production and ecological sustainability.The expanding role of land in a 1.5 C world will be twofold — to remove carbon dioxide from the atmosphere and to produce clean energy. Land-based carbon dioxide removal strategies include bioenergy with carbon capture and storage; direct air capture; and afforestation/reforestation and other nature-based solutions. Land-based clean energy production includes wind and solar farms and sustainable bioenergy cropland. Any decision to allocate more land for climate mitigation must also address competing needs for long-term food security and ecosystem health.Land-based climate mitigation choices vary in terms of costs — amount of land required, implications for food security, impact on biodiversity and other ecosystem services — and benefits — potential for sequestering greenhouse gases and producing clean energy.Now a study in the journal Frontiers in Environmental Science provides the most comprehensive analysis to date of competing land-use and technology options to limit global warming to 1.5 C. Led by researchers at the MIT Center for Sustainability Science and Strategy (CS3), the study applies the MIT Integrated Global System Modeling (IGSM) framework to evaluate costs and benefits of different land-based climate mitigation options in Sky2050, a 1.5 C climate-stabilization scenario developed by Shell.Under this scenario, demand for bioenergy and natural carbon sinks increase along with the need for sustainable farming and food production. To determine if there’s enough land to meet all these growing demands, the research team uses the global hectare (gha) — an area of 10,000 square meters, or 2.471 acres — as the standard unit of measurement, and current estimates of the Earth’s total habitable land area (about 10 gha) and land area used for food production and bioenergy (5 gha).The team finds that with transformative changes in policy, land management practices, and consumption patterns, global land is sufficient to provide a sustainable supply of food and ecosystem services throughout this century while also reducing greenhouse gas emissions in alignment with the 1.5 C goal. These transformative changes include policies to protect natural ecosystems; stop deforestation and accelerate reforestation and afforestation; promote advances in sustainable agriculture technology and practice; reduce agricultural and food waste; and incentivize consumers to purchase sustainably produced goods.If such changes are implemented, 2.5–3.5 gha of land would be used for NBS practices to sequester 3–6 gigatonnes (Gt) of CO2 per year, and 0.4–0.6 gha of land would be allocated for energy production — 0.2–0.3 gha for bioenergy and 0.2–0.35 gha for wind and solar power generation.“Our scenario shows that there is enough land to support a 1.5 degree C future as long as effective policies at national and global levels are in place,” says CS3 Principal Research Scientist Angelo Gurgel, the study’s lead author. “These policies must not only promote efficient use of land for food, energy, and nature, but also be supported by long-term commitments from government and industry decision-makers.” More

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      Decarbonizing heavy industry with thermal batteries

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      Whether you’re manufacturing cement, steel, chemicals, or paper, you need a large amount of heat. Almost without exception, manufacturers around the world create that heat by burning fossil fuels.In an effort to clean up the industrial sector, some startups are changing manufacturing processes for specific materials. Some are even changing the materials themselves. Daniel Stack SM ’17, PhD ’21 is trying to address industrial emissions across the board by replacing the heat source.Since coming to MIT in 2014, Stack has worked to develop thermal batteries that use electricity to heat up a conductive version of ceramic firebricks, which have been used as heat stores and insulators for centuries. In 2021, Stack co-founded Electrified Thermal Solutions, which has since demonstrated that its firebricks can store heat efficiently for hours and discharge it by heating air or gas up to 3,272 degrees Fahrenheit — hot enough to power the most demanding industrial applications.Achieving temperatures north of 3,000 F represents a breakthrough for the electric heating industry, as it enables some of the world’s hardest-to-decarbonize sectors to utilize renewable energy for the first time. It also unlocks a new, low-cost model for using electricity when it’s at its cheapest and cleanest.“We have a global perspective at Electrified Thermal, but in the U.S. over the last five years, we’ve seen an incredible opportunity emerge in energy prices that favors flexible offtake of electricity,” Stack says. “Throughout the middle of the country, especially in the wind belt, electricity prices in many places are negative for more than 20 percent of the year, and the trend toward decreasing electricity pricing during off-peak hours is a nationwide phenomenon. Technologies like our Joule Hive Thermal Battery will enable us to access this inexpensive, clean electricity and compete head to head with fossil fuels on price for industrial heating needs, without even factoring in the positive climate impact.”A new approach to an old technologyStack’s research plans changed quickly when he joined MIT’s Department of Nuclear Science and Engineering as a master’s student in 2014.“I went to MIT excited to work on the next generation of nuclear reactors, but what I focused on almost from day one was how to heat up bricks,” Stack says. “It wasn’t what I expected, but when I talked to my advisor, [Principal Research Scientist] Charles Forsberg, about energy storage and why it was valuable to not just nuclear power but the entire energy transition, I realized there was no project I would rather work on.”Firebricks are ubiquitous, inexpensive clay bricks that have been used for millennia in fireplaces and ovens. In 2017, Forsberg and Stack co-authored a paper showing firebricks’ potential to store heat from renewable resources, but the system still used electric resistance heaters — like the metal coils in toasters and space heaters — which limited its temperature output.For his doctoral work, Stack worked with Forsberg to make firebricks that were electrically conductive, replacing the resistance heaters so the bricks produced the heat directly.“Electric heaters are your biggest limiter: They burn out too fast, they break down, they don’t get hot enough,” Stack explains. “The idea was to skip the heaters because firebricks themselves are really cheap, abundant materials that can go to flame-like temperatures and hang out there for days.”Forsberg and Stacks were able to create conductive firebricks by tweaking the chemical composition of traditional firebricks. Electrified Thermal’s bricks are 98 percent similar to existing firebricks and are produced using the same processes, allowing existing manufacturers to make them inexpensively.Toward the end of his PhD program, Stack realized the invention could be commercialized. He started taking classes at the MIT Sloan School of Management and spending time at the Martin Trust Center for MIT Entrepreneurship. He also entered the StartMIT program and the I-Corps program, and received support from the U.S. Department of Energy and MIT’s Venture Mentoring Service (VMS).“Through the Boston ecosystem, the MIT ecosystem, and with help from the Department of Energy, we were able to launch this from the lab at MIT,” Stack says. “What we spun out was an electrically conductive firebrick, or what we refer to as an e-Brick.”Electrified Thermal contains its firebrick arrays in insulated, off-the-shelf metal boxes. Although the system is highly configurable depending on the end use, the company’s standard system can collect and release about 5 megawatts of energy and store about 25 megawatt-hours.The company has demonstrated its system’s ability to produce high temperatures and has been cycling its system at its headquarters in Medford, Massachusetts. That work has collectively earned Electrified Thermal $40 million from various the Department of Energy offices to scale the technology and work with manufacturers.“Compared to other electric heating, we can run hotter and last longer than any other solution on the market,” Stack says. “That means replacing fossil fuels at a lot of industrial sites that couldn’t otherwise decarbonize.”Scaling to solve a global problemElectrified Thermal is engaging with hundreds of industrial companies, including manufacturers of cement, steel, glass, basic and specialty chemicals, food and beverage, and pulp and paper.“The industrial heating challenge affects everyone under the sun,” Stack says. “They all have fundamentally the same problem, which is getting their heat in a way that is affordable and zero carbon for the energy transition.”The company is currently building a megawatt-scale commercial version of its system, which it expects to be operational in the next seven months.“Next year will be a huge proof point to the industry,” Stack says. “We’ll be using the commercial system to showcase a variety of operating points that customers need to see, and we’re hoping to be running systems on customer sites by the end of the year. It’ll be a huge achievement and a first for electric heating because no other solution in the market can put out the kind of temperatures that we can put out.”By working with manufacturers to produce its firebricks and casings, Electrified Thermal hopes to be able to deploy its systems rapidly and at low cost across a massive industry.“From the very beginning, we engineered these e-bricks to be rapidly scalable and rapidly producible within existing supply chains and manufacturing processes,” Stack says. “If you want to decarbonize heavy industry, there will be no cheaper way than turning electricity into heat from zero-carbon electricity assets. We’re seeking to be the premier technology that unlocks those capabilities, with double digit percentages of global energy flowing through our system as we accomplish the energy transition.” More

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      New solar projects will grow renewable energy generation for four major campus buildings

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      In the latest step to implement commitments made in MIT’s Fast Forward climate action plan, staff from the Department of Facilities; Office of Sustainability; and Environment, Health and Safety Office are advancing new solar panel installations this fall and winter on four major campus buildings: The Stratton Student Center (W20), the Dewey Library building (E53), and two newer buildings, New Vassar (W46) and the Theater Arts building (W97).These four new installations, in addition to existing rooftop solar installations on campus, are “just one part of our broader strategy to reduce MIT’s carbon footprint and transition to clean energy,” says Joe Higgins, vice president for campus services and stewardship.The installations will not only meet but exceed the target set for total solar energy production on campus in the Fast Forward climate action plan that was issued in 2021. With an initial target of 500 kilowatts of installed solar capacity on campus, the new installations, along with those already in place, will bring the total output to roughly 650 kW, exceeding the goal. The solar installations are an important facet of MIT’s approach to eliminating all direct campus emissions by 2050.The process of advancing to the stage of placing solar panels on campus rooftops is much more complex than just getting them installed on an ordinary house. The process began with a detailed assessment of the potential for reducing the campus greenhouse gas footprint. A first cut eliminated rooftops that were too shaded by trees or other buildings. Then, the schedule for regular replacement of roofs had to be taken into account — it’s better to put new solar panels on top of a roof that will not need replacement in a few years. Other roofs, especially lab buildings, simply had too much existing equipment on them to allow a large area of space for solar panels.Randa Ghattas, senior sustainability project manager, and Taya Dixon, assistant director for capital budgets and contracts within the Department of Facilities, spearheaded the project. Their initial assessment showed that there were many buildings identified with significant solar potential, and it took the impetus of the Fast Forward plan to kick things into action. Even after winnowing down the list of campus buildings based on shading and the life cycle of roof replacements, there were still many other factors to consider. Some buildings that had ample roof space were of older construction that couldn’t bear the loads of a full solar installation without significant reconstruction. “That actually has proved trickier than we thought,” Ghattas says. For example, one building that seemed a good candidate, and already had some solar panels on it, proved unable to sustain the greater weight and wind loads of a full solar installation. Structural capacity, she says, turned out to be “probably the most important” factor in this case.The roofs on the Student Center and on the Dewey Library building were replaced in the last few years with the intention of the later addition of solar panels. And the two newer buildings were designed from the beginning with solar in mind, even though the solar panels were not part of the initial construction. “The designs were built into them to accommodate solar,” Dixon says, “so those were easy options for us because we knew the buildings were solar-ready and could support solar being integrated into their systems, both the electrical system and the structural system of the roof.”But there were also other considerations. The Student Center is considered a historically significant building, so the installation had to be designed so that it was invisible from street level, even including a safety railing that had to be built around the solar array. But that was not a problem. “It was fine for this building,” Ghattas says, because it turned out that the geometry of the building and the roofs hid the safety railing from view below.Each installation will connect directly to the building’s electrical system, and thus into the campus grid. The power they produce will be used in the buildings they are on, though none will be sufficient to fully power its building. Overall, the new installations, in addition to the existing ones on the MIT Sloan School of Management building (E62) and the Alumni Pool (57) and the planned array on the new Graduate Junction dorm (W87-W88), will be enough to power 5 to 10 percent of the buildings’ electric needs, and offset about 190 metric tons of carbon dioxide emissions each year, Ghattas says. This is equivalent to the electricity use of 35 homes annually.Each building installation is expected to take just a couple of weeks. “We’re hopeful that we’re going to have everything installed and operational by the end of this calendar year,” she says.Other buildings could be added in coming years, as their roof replacement cycles come around. With the lessons learned along the way in getting to this point, Ghattas says, “now that we have a system in place, hopefully it’s going to be much easier in the future.”Higgins adds that “in parallel with the solar projects, we’re working on expanding electric vehicle charging stations and the electric vehicle fleet and reducing energy consumption in campus buildings.”Besides the on-campus improvements, he says, “MIT is focused on both the local and the global.” In addition to solar installations on campus buildings, which can only mitigate a small portion of campus emissions, “large-scale aggregation partnerships are key to moving the actual market landscape for adding cleaner energy generation to power grids,” which must ultimately lead to zero emissions, he says. “We are spurring the development of new utility-grade renewable energy facilities in regions with high carbon-intensive electrical grids. These projects have an immediate and significant impact in the urgently needed decarbonization of regional power grids.”MIT is also making more advances to accelerate renewable energy generation and electricity grid decarbonization at the local and state level. The Institute has recently concluded an agreement through the Solar Massachusetts Renewable Target program that supports the Commonwealth of Massachusetts’ state solar power development goals by enabling the construction of a new 5-megawatt solar energy facility on Cape Cod. The new solar energy system is integral to supporting a new net-zero emissions development that includes affordable housing, while also providing additional resiliency to the local grid.Higgins says that other technologies, strategies, and practices are being evaluated for heating, cooling, and power for the campus, “with zero carbon emissions by 2050, utilizing cleaner energy sources.” He adds that these campus initiatives “are part of MIT’s larger Climate Project, aiming to drive progress both on campus and beyond, advancing broader partnerships, new market models, and informing approaches to climate policy.”  More