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      in Energy

      Using aluminum and water to make clean hydrogen fuel — when and where it’s needed

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      As the world works to move away from fossil fuels, many researchers are investigating whether clean hydrogen fuel can play an expanded role in sectors from transportation and industry to buildings and power generation. It could be used in fuel cell vehicles, heat-producing boilers, electricity-generating gas turbines, systems for storing renewable energy, and more.

      But while using hydrogen doesn’t generate carbon emissions, making it typically does. Today, almost all hydrogen is produced using fossil fuel-based processes that together generate more than 2 percent of all global greenhouse gas emissions. In addition, hydrogen is often produced in one location and consumed in another, which means its use also presents logistical challenges.

      A promising reaction

      Another option for producing hydrogen comes from a perhaps surprising source: reacting aluminum with water. Aluminum metal will readily react with water at room temperature to form aluminum hydroxide and hydrogen. That reaction doesn’t typically take place because a layer of aluminum oxide naturally coats the raw metal, preventing it from coming directly into contact with water.

      Using the aluminum-water reaction to generate hydrogen doesn’t produce any greenhouse gas emissions, and it promises to solve the transportation problem for any location with available water. Simply move the aluminum and then react it with water on-site. “Fundamentally, the aluminum becomes a mechanism for storing hydrogen — and a very effective one,” says Douglas P. Hart, professor of mechanical engineering at MIT. “Using aluminum as our source, we can ‘store’ hydrogen at a density that’s 10 times greater than if we just store it as a compressed gas.”

      Two problems have kept aluminum from being employed as a safe, economical source for hydrogen generation. The first problem is ensuring that the aluminum surface is clean and available to react with water. To that end, a practical system must include a means of first modifying the oxide layer and then keeping it from re-forming as the reaction proceeds.

      The second problem is that pure aluminum is energy-intensive to mine and produce, so any practical approach needs to use scrap aluminum from various sources. But scrap aluminum is not an easy starting material. It typically occurs in an alloyed form, meaning that it contains other elements that are added to change the properties or characteristics of the aluminum for different uses. For example, adding magnesium increases strength and corrosion-resistance, adding silicon lowers the melting point, and adding a little of both makes an alloy that’s moderately strong and corrosion-resistant.

      Despite considerable research on aluminum as a source of hydrogen, two key questions remain: What’s the best way to prevent the adherence of an oxide layer on the aluminum surface, and how do alloying elements in a piece of scrap aluminum affect the total amount of hydrogen generated and the rate at which it is generated?

      “If we’re going to use scrap aluminum for hydrogen generation in a practical application, we need to be able to better predict what hydrogen generation characteristics we’re going to observe from the aluminum-water reaction,” says Laureen Meroueh PhD ’20, who earned her doctorate in mechanical engineering.

      Since the fundamental steps in the reaction aren’t well understood, it’s been hard to predict the rate and volume at which hydrogen forms from scrap aluminum, which can contain varying types and concentrations of alloying elements. So Hart, Meroueh, and Thomas W. Eagar, a professor of materials engineering and engineering management in the MIT Department of Materials Science and Engineering, decided to examine — in a systematic fashion — the impacts of those alloying elements on the aluminum-water reaction and on a promising technique for preventing the formation of the interfering oxide layer.

      To prepare, they had experts at Novelis Inc. fabricate samples of pure aluminum and of specific aluminum alloys made of commercially pure aluminum combined with either 0.6 percent silicon (by weight), 1 percent magnesium, or both — compositions that are typical of scrap aluminum from a variety of sources. Using those samples, the MIT researchers performed a series of tests to explore different aspects of the aluminum-water reaction.

      Pre-treating the aluminum

      The first step was to demonstrate an effective means of penetrating the oxide layer that forms on aluminum in the air. Solid aluminum is made up of tiny grains that are packed together with occasional boundaries where they don’t line up perfectly. To maximize hydrogen production, researchers would need to prevent the formation of the oxide layer on all those interior grain surfaces.

      Research groups have already tried various ways of keeping the aluminum grains “activated” for reaction with water. Some have crushed scrap samples into particles so tiny that the oxide layer doesn’t adhere. But aluminum powders are dangerous, as they can react with humidity and explode. Another approach calls for grinding up scrap samples and adding liquid metals to prevent oxide deposition. But grinding is a costly and energy-intensive process.

      To Hart, Meroueh, and Eagar, the most promising approach — first introduced by Jonathan Slocum ScD ’18 while he was working in Hart’s research group — involved pre-treating the solid aluminum by painting liquid metals on top and allowing them to permeate through the grain boundaries.

      To determine the effectiveness of that approach, the researchers needed to confirm that the liquid metals would reach the internal grain surfaces, with and without alloying elements present. And they had to establish how long it would take for the liquid metal to coat all of the grains in pure aluminum and its alloys.

      They started by combining two metals — gallium and indium — in specific proportions to create a “eutectic” mixture; that is, a mixture that would remain in liquid form at room temperature. They coated their samples with the eutectic and allowed it to penetrate for time periods ranging from 48 to 96 hours. They then exposed the samples to water and monitored the hydrogen yield (the amount formed) and flow rate for 250 minutes. After 48 hours, they also took high-magnification scanning electron microscope (SEM) images so they could observe the boundaries between adjacent aluminum grains.

      Based on the hydrogen yield measurements and the SEM images, the MIT team concluded that the gallium-indium eutectic does naturally permeate and reach the interior grain surfaces. However, the rate and extent of penetration vary with the alloy. The permeation rate was the same in silicon-doped aluminum samples as in pure aluminum samples but slower in magnesium-doped samples.

      Perhaps most interesting were the results from samples doped with both silicon and magnesium — an aluminum alloy often found in recycling streams. Silicon and magnesium chemically bond to form magnesium silicide, which occurs as solid deposits on the internal grain surfaces. Meroueh hypothesized that when both silicon and magnesium are present in scrap aluminum, those deposits can act as barriers that impede the flow of the gallium-indium eutectic.

      The experiments and images confirmed her hypothesis: The solid deposits did act as barriers, and images of samples pre-treated for 48 hours showed that permeation wasn’t complete. Clearly, a lengthy pre-treatment period would be critical for maximizing the hydrogen yield from scraps of aluminum containing both silicon and magnesium.

      Meroueh cites several benefits to the process they used. “You don’t have to apply any energy for the gallium-indium eutectic to work its magic on aluminum and get rid of that oxide layer,” she says. “Once you’ve activated your aluminum, you can drop it in water, and it’ll generate hydrogen — no energy input required.” Even better, the eutectic doesn’t chemically react with the aluminum. “It just physically moves around in between the grains,” she says. “At the end of the process, I could recover all of the gallium and indium I put in and use it again” — a valuable feature as gallium and (especially) indium are costly and in relatively short supply.

      Impacts of alloying elements on hydrogen generation

      The researchers next investigated how the presence of alloying elements affects hydrogen generation. They tested samples that had been treated with the eutectic for 96 hours; by then, the hydrogen yield and flow rates had leveled off in all the samples.

      The presence of 0.6 percent silicon increased the hydrogen yield for a given weight of aluminum by 20 percent compared to pure aluminum — even though the silicon-containing sample had less aluminum than the pure aluminum sample. In contrast, the presence of 1 percent magnesium produced far less hydrogen, while adding both silicon and magnesium pushed the yield up, but not to the level of pure aluminum.

      The presence of silicon also greatly accelerated the reaction rate, producing a far higher peak in the flow rate but cutting short the duration of hydrogen output. The presence of magnesium produced a lower flow rate but allowed the hydrogen output to remain fairly steady over time. And once again, aluminum with both alloying elements produced a flow rate between that of magnesium-doped and pure aluminum.

      Those results provide practical guidance on how to adjust the hydrogen output to match the operating needs of a hydrogen-consuming device. If the starting material is commercially pure aluminum, adding small amounts of carefully selected alloying elements can tailor the hydrogen yield and flow rate. If the starting material is scrap aluminum, careful choice of the source can be key. For high, brief bursts of hydrogen, pieces of silicon-containing aluminum from an auto junkyard could work well. For lower but longer flows, magnesium-containing scraps from the frame of a demolished building might be better. For results somewhere in between, aluminum containing both silicon and magnesium should work well; such material is abundantly available from scrapped cars and motorcycles, yachts, bicycle frames, and even smartphone cases.

      It should also be possible to combine scraps of different aluminum alloys to tune the outcome, notes Meroueh. “If I have a sample of activated aluminum that contains just silicon and another sample that contains just magnesium, I can put them both into a container of water and let them react,” she says. “So I get the fast ramp-up in hydrogen production from the silicon and then the magnesium takes over and has that steady output.”

      Another opportunity for tuning: Reducing grain size

      Another practical way to affect hydrogen production could be to reduce the size of the aluminum grains — a change that should increase the total surface area available for reactions to occur.

      To investigate that approach, the researchers requested specially customized samples from their supplier. Using standard industrial procedures, the Novelis experts first fed each sample through two rollers, squeezing it from the top and bottom so that the internal grains were flattened. They then heated each sample until the long, flat grains had reorganized and shrunk to a targeted size.

      In a series of carefully designed experiments, the MIT team found that reducing the grain size increased the efficiency and decreased the duration of the reaction to varying degrees in the different samples. Again, the presence of particular alloying elements had a major effect on the outcome.

      Needed: A revised theory that explains observations

      Throughout their experiments, the researchers encountered some unexpected results. For example, standard corrosion theory predicts that pure aluminum will generate more hydrogen than silicon-doped aluminum will — the opposite of what they observed in their experiments.

      To shed light on the underlying chemical reactions, Hart, Meroueh, and Eagar investigated hydrogen “flux,” that is, the volume of hydrogen generated over time on each square centimeter of aluminum surface, including the interior grains. They examined three grain sizes for each of their four compositions and collected thousands of data points measuring hydrogen flux.

      Their results show that reducing grain size has significant effects. It increases the peak hydrogen flux from silicon-doped aluminum as much as 100 times and from the other three compositions by 10 times. With both pure aluminum and silicon-containing aluminum, reducing grain size also decreases the delay before the peak flux and increases the rate of decline afterward. With magnesium-containing aluminum, reducing the grain size brings about an increase in peak hydrogen flux and results in a slightly faster decline in the rate of hydrogen output. With both silicon and magnesium present, the hydrogen flux over time resembles that of magnesium-containing aluminum when the grain size is not manipulated. When the grain size is reduced, the hydrogen output characteristics begin to resemble behavior observed in silicon-containing aluminum. That outcome was unexpected because when silicon and magnesium are both present, they react to form magnesium silicide, resulting in a new type of aluminum alloy with its own properties.

      The researchers stress the benefits of developing a better fundamental understanding of the underlying chemical reactions involved. In addition to guiding the design of practical systems, it might help them find a replacement for the expensive indium in their pre-treatment mixture. Other work has shown that gallium will naturally permeate through the grain boundaries of aluminum. “At this point, we know that the indium in our eutectic is important, but we don’t really understand what it does, so we don’t know how to replace it,” says Hart.

      But already Hart, Meroueh, and Eagar have demonstrated two practical ways of tuning the hydrogen reaction rate: by adding certain elements to the aluminum and by manipulating the size of the interior aluminum grains. In combination, those approaches can deliver significant results. “If you go from magnesium-containing aluminum with the largest grain size to silicon-containing aluminum with the smallest grain size, you get a hydrogen reaction rate that differs by two orders of magnitude,” says Meroueh. “That’s huge if you’re trying to design a real system that would use this reaction.”

      This research was supported through the MIT Energy Initiative by ExxonMobil-MIT Energy Fellowships awarded to Laureen Meroueh PhD ’20 from 2018 to 2020.

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

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      in Energy

      Electrifying cars and light trucks to meet Paris climate goals

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      On Aug. 5, the White House announced that it seeks to ensure that 50 percent of all new passenger vehicles sold in the United States by 2030 are powered by electricity. The purpose of this target is to enable the U.S to remain competitive with China in the growing electric vehicle (EV) market and meet its international climate commitments. Setting ambitious EV sales targets and transitioning to zero-carbon power sources in the United States and other nations could lead to significant reductions in carbon dioxide and other greenhouse gas emissions in the transportation sector and move the world closer to achieving the Paris Agreement’s long-term goal of keeping global warming well below 2 degrees Celsius relative to preindustrial levels.

      At this time, electrification of the transportation sector is occurring primarily in private light-duty vehicles (LDVs). In 2020, the global EV fleet exceeded 10 million, but that’s a tiny fraction of the cars and light trucks on the road. How much of the LDV fleet will need to go electric to keep the Paris climate goal in play? 

      To help answer that question, researchers at the MIT Joint Program on the Science and Policy of Global Change and MIT Energy Initiative have assessed the potential impacts of global efforts to reduce carbon dioxide emissions on the evolution of LDV fleets over the next three decades.

      Using an enhanced version of the multi-region, multi-sector MIT Economic Projection and Policy Analysis (EPPA) model that includes a representation of the household transportation sector, they projected changes for the 2020-50 period in LDV fleet composition, carbon dioxide emissions, and related impacts for 18 different regions. Projections were generated under four increasingly ambitious climate mitigation scenarios: a “Reference” scenario based on current market trends and fuel efficiency policies, a “Paris Forever” scenario in which current Paris Agreement commitments (Nationally Determined Contributions, or NDCs) are maintained but not strengthened after 2030, a “Paris to 2 C” scenario in which decarbonization actions are enhanced to be consistent with capping global warming at 2 C, and an “Accelerated Actions” scenario the caps global warming at 1.5 C through much more aggressive emissions targets than the current NDCs.

      Based on projections spanning the first three scenarios, the researchers found that the global EV fleet will likely grow to about 95-105 million EVs by 2030, and 585-823 million EVs by 2050. In the Accelerated Actions scenario, global EV stock reaches more than 200 million vehicles in 2030, and more than 1 billion in 2050, accounting for two-thirds of the global LDV fleet. The research team also determined that EV uptake will likely grow but vary across regions over the 30-year study time frame, with China, the United States, and Europe remaining the largest markets. Finally, the researchers found that while EVs play a role in reducing oil use, a more substantial reduction in oil consumption comes from economy-wide carbon pricing. The results appear in a study in the journal Economics of Energy & Environmental Policy.

      “Our study shows that EVs can contribute significantly to reducing global carbon emissions at a manageable cost,” says MIT Joint Program Deputy Director and MIT Energy Initiative Senior Research Scientist Sergey Paltsev, the lead author. “We hope that our findings will help decision-makers to design efficient pathways to reduce emissions.”  

      To boost the EV share of the global LDV fleet, the study’s co-authors recommend more ambitious policies to mitigate climate change and decarbonize the electric grid. They also envision an “integrated system approach” to transportation that emphasizes making internal combustion engine vehicles more efficient, a long-term shift to low- and net-zero carbon fuels, and systemic efficiency improvements through digitalization, smart pricing, and multi-modal integration. While the study focuses on EV deployment, the authors also stress for the need for investment in all possible decarbonization options related to transportation, including enhancing public transportation, avoiding urban sprawl through strategic land-use planning, and reducing the use of private motorized transport by mode switching to walking, biking, and mass transit.

      This research is an extension of the authors’ contribution to the MIT Mobility of the Future study. More

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      in Energy

      Amy Watterson: Model engineer

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      “I love that we are doing something that no one else is doing.”

      Amy Watterson is excited when she talks about SPARC, the pilot fusion plant being developed by MIT spinoff Commonwealth Fusion Systems (CSF). Since being hired as a mechanical engineer at the Plasma Science and Fusion Center (PSFC) two years ago, Watterson has found her skills stretching to accommodate the multiple needs of the project.

      Fusion, which fuels the sun and stars, has long been sought as a carbon-free energy source for the world. For decades researchers have pursued the “tokamak,” a doughnut-shaped vacuum chamber where hot plasma can be contained by magnetic fields and heated to the point where fusion occurs. Sustaining the fusion reactions long enough to draw energy from them has been a challenge.

      Watterson is intimately aware of this difficulty. Much of her life she has heard the quip, “Fusion is 50 years away and always will be.” The daughter of PSFC research scientist Catherine Fiore, who headed the PSFC’s Office of Environment, Safety and Health, and Reich Watterson, an optical engineer working at the center, she had watched her parents devote years to making fusion a reality. She determined before entering Rensselaer Polytechnic Institute that she could forgo any attempt to follow her parents into a field that might not produce results during her career.

      Working on SPARC has changed her mindset. Taking advantage of a novel high-temperature superconducting tape, SPARC’s magnets will be compact while generating magnetic fields stronger than would be possible from other mid-sized tokamaks, and producing more fusion power. It suggests a high-field device that produces net fusion gain is not 50 years away. SPARC is scheduled to be begin operation in 2025.

      An education in modeling

      Watterson’s current excitement, and focus, is due to an approaching milestone for SPARC: a test of the Toroidal Field Magnet Coil (TFMC), a scaled prototype for the HTS magnets that will surround SPARC’s toroidal vacuum chamber. Its design and manufacture have been shaped by computer models and simulations. As part of a large research team, Waterson has received an education in modeling over the past two years.

      Computer models move scientific experiments forward by allowing researchers to predict what will happen to an experiment — or its materials — if a parameter is changed. Modeling a component of the TFMC, for example, researchers can test how it is affected by varying amounts of current, different temperatures or different materials. With this information they can make choices that will improve the success of the experiment.

      In preparation for the magnet testing, Watterson has modeled aspects of the cryogenic system that will circulate helium gas around the TFMC to keep it cold enough to remain superconducting. Taking into consideration the amount of cooling entering the system, the flow rate of the helium, the resistance created by valves and transfer lines and other parameters, she can model how much helium flow will be necessary to guarantee the magnet stays cold enough. Adjusting a parameter can make the difference between a magnet remaining superconducting and becoming overheated or even damaged.

      Watterson and her teammates have also modeled pressures and stress on the inside of the TFMC. Pumping helium through the coil to cool it down will add 20 atmospheres of pressure, which could create a degree of flex in elements of the magnet that are welded down. Modeling can help determine how much pressure a weld can sustain.

      “How thick does a weld need to be, and where should you put the weld so that it doesn’t break — that’s something you don’t want to leave until you’re finally assembling it,” says Watterson.

      Modeling the behavior of helium is particularly challenging because its properties change significantly as the pressure and temperature change.

      “A few degrees or a little pressure will affect the fluid’s viscosity, density, thermal conductivity, and heat capacity,” says Watterson. “The flow has different pressures and temperatures at different places in the cryogenic loop. You end up with a set of equations that are very dependent on each other, which makes it a challenge to solve.”

      Role model

      Watterson notes that her modeling depends on the contributions of colleagues at the PSFC, and praises the collaborative spirit among researchers and engineers, a community that now feels like family. Her teammates have been her mentors. “I’ve learned so much more on the job in two years than I did in four years at school,” she says.

      She realizes that having her mother as a role model in her own family has always made it easier for her to imagine becoming a scientist or engineer. Tracing her early passion for engineering to a middle school Lego robotics tournament, her eyes widen as she talks about the need for more female engineers, and the importance of encouraging girls to believe they are equal to the challenge.

      “I want to be a role model and tell them ‘I’m a successful engineer, you can be too.’ Something I run into a lot is that little girls will say, ‘I can’t be an engineer, I’m not cut out for that.’ And I say, ‘Well that’s not true. Let me show you. If you can make this Lego robot, then you can be an engineer.’ And it turns out they usually can.”

      Then, as if making an adjustment to one of her computer models, she continues.

      “Actually, they always can.” More

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      in Environment

      What will happen to sediment plumes associated with deep-sea mining?

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      In certain parts of the deep ocean, scattered across the seafloor, lie baseball-sized rocks layered with minerals accumulated over millions of years. A region of the central Pacific, called the Clarion Clipperton Fracture Zone (CCFZ), is estimated to contain vast reserves of these rocks, known as “polymetallic nodules,” that are rich in nickel and cobalt  — minerals that are commonly mined on land for the production of lithium-ion batteries in electric vehicles, laptops, and mobile phones.

      As demand for these batteries rises, efforts are moving forward to mine the ocean for these mineral-rich nodules. Such deep-sea-mining schemes propose sending down tractor-sized vehicles to vacuum up nodules and send them to the surface, where a ship would clean them and discharge any unwanted sediment back into the ocean. But the impacts of deep-sea mining — such as the effect of discharged sediment on marine ecosystems and how these impacts compare to traditional land-based mining — are currently unknown.

      Now oceanographers at MIT, the Scripps Institution of Oceanography, and elsewhere have carried out an experiment at sea for the first time to study the turbulent sediment plume that mining vessels would potentially release back into the ocean. Based on their observations, they developed a model that makes realistic predictions of how a sediment plume generated by mining operations would be transported through the ocean.

      The model predicts the size, concentration, and evolution of sediment plumes under various marine and mining conditions. These predictions, the researchers say, can now be used by biologists and environmental regulators to gauge whether and to what extent such plumes would impact surrounding sea life.

      “There is a lot of speculation about [deep-sea-mining’s] environmental impact,” says Thomas Peacock, professor of mechanical engineering at MIT. “Our study is the first of its kind on these midwater plumes, and can be a major contributor to international discussion and the development of regulations over the next two years.”

      The team’s study appears today in Nature Communications: Earth and Environment.

      Peacock’s co-authors at MIT include lead author Carlos Muñoz-Royo, Raphael Ouillon, Chinmay Kulkarni, Patrick Haley, Chris Mirabito, Rohit Supekar, Andrew Rzeznik, Eric Adams, Cindy Wang, and Pierre Lermusiaux, along with collaborators at Scripps, the U.S. Geological Survey, and researchers in Belgium and South Korea.

      Play video

      Out to sea

      Current deep-sea-mining proposals are expected to generate two types of sediment plumes in the ocean: “collector plumes” that vehicles generate on the seafloor as they drive around collecting nodules 4,500 meters below the surface; and possibly “midwater plumes” that are discharged through pipes that descend 1,000 meters or more into the ocean’s aphotic zone, where sunlight rarely penetrates.

      In their new study, Peacock and his colleagues focused on the midwater plume and how the sediment would disperse once discharged from a pipe.

      “The science of the plume dynamics for this scenario is well-founded, and our goal was to clearly establish the dynamic regime for such plumes to properly inform discussions,” says Peacock, who is the director of MIT’s Environmental Dynamics Laboratory.

      To pin down these dynamics, the team went out to sea. In 2018, the researchers boarded the research vessel Sally Ride and set sail 50 kilometers off the coast of Southern California. They brought with them equipment designed to discharge sediment 60 meters below the ocean’s surface.  

      “Using foundational scientific principles from fluid dynamics, we designed the system so that it fully reproduced a commercial-scale plume, without having to go down to 1,000 meters or sail out several days to the middle of the CCFZ,” Peacock says.

      Over one week the team ran a total of six plume experiments, using novel sensors systems such as a Phased Array Doppler Sonar (PADS) and epsilometer developed by Scripps scientists to monitor where the plumes traveled and how they evolved in shape and concentration. The collected data revealed that the sediment, when initially pumped out of a pipe, was a highly turbulent cloud of suspended particles that mixed rapidly with the surrounding ocean water.

      “There was speculation this sediment would form large aggregates in the plume that would settle relatively quickly to the deep ocean,” Peacock says. “But we found the discharge is so turbulent that it breaks the sediment up into its finest constituent pieces, and thereafter it becomes dilute so quickly that the sediment then doesn’t have a chance to stick together.”

      Dilution

      The team had previously developed a model to predict the dynamics of a plume that would be discharged into the ocean. When they fed the experiment’s initial conditions into the model, it produced the same behavior that the team observed at sea, proving the model could accurately predict plume dynamics within the vicinity of the discharge.

      The researchers used these results to provide the correct input for simulations of ocean dynamics to see how far currents would carry the initially released plume.

      “In a commercial operation, the ship is always discharging new sediment. But at the same time the background turbulence of the ocean is always mixing things. So you reach a balance. There’s a natural dilution process that occurs in the ocean that sets the scale of these plumes,” Peacock says. “What is key to determining the extent of the plumes is the strength of the ocean turbulence, the amount of sediment that gets discharged, and the environmental threshold level at which there is impact.”

      Based on their findings, the researchers have developed formulae to calculate the scale of a plume depending on a given environmental threshold. For instance, if regulators determine that a certain concentration of sediments could be detrimental to surrounding sea life, the formula can be used to calculate how far a plume above that concentration would extend, and what volume of ocean water would be impacted over the course of a 20-year nodule mining operation.

      “At the heart of the environmental question surrounding deep-sea mining is the extent of sediment plumes,” Peacock says. “It’s a multiscale problem, from micron-scale sediments, to turbulent flows, to ocean currents over thousands of kilometers. It’s a big jigsaw puzzle, and we are uniquely equipped to work on that problem and provide answers founded in science and data.”

      The team is now working on collector plumes, having recently returned from several weeks at sea to perform the first environmental monitoring of a nodule collector vehicle in the deep ocean in over 40 years.

      This research was supported in part by the MIT Environmental Solutions Initiative, the UC Ship Time Program, the MIT Policy Lab, the 11th Hour Project of the Schmidt Family Foundation, the Benioff Ocean Initiative, and Fundación Bancaria “la Caixa.” More

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      in Energy

      Manipulating magnets in the quest for fusion

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      “You get the high field, you get the performance.”

      Senior Research Scientist Brian LaBombard is summarizing what might be considered a guiding philosophy behind designing and engineering fusion devices at MIT’s Plasma Science and Fusion Center (PSFC). Beginning in 1972 with the Alcator A tokamak, through Alcator C (1978) and Alcator C-Mod (1991), the PSFC has used magnets with high fields to confine the hot plasma in compact, high-performance tokamaks. Joining what was then the Plasma Fusion Center as a graduate student in 1978, just as Alcator A was finishing its run, LaBombard is one of the few who has worked with each iteration of the high-field concept. Now he has turned his attention to the PSFC’s latest fusion venture, a fusion energy project called SPARC.

      Designed in collaboration with MIT spinoff Commonwealth Fusion Systems (CFS), SPARC employs novel high temperature superconducting (HTS) magnets at high-field to achieve fusion that will produce net energy gain. Some of these magnets will wrap toroidally around the tokamak’s doughnut-shaped vacuum chamber, confining fusion reactions and preventing damage to the walls of the device.

      The PSFC has spent three years researching, developing, and manufacturing a scaled version of these toroidal field (TF) coils — the toroidal field model coil, or TFMC. Before the TF coils can be built for SPARC, LaBombard and his team need to test the model coil under the conditions that it will experience in this tokamak.

      HTS magnets need to be cooled in order to remain superconducting, and to be protected from the heat generated by current. For testing, the TFMC will be enclosed in a cryostat, cooled to the low temperatures needed for eventual tokamak operation, and charged with current to produce magnetic field. How the magnet responds as the current is provided to the coil will determine if the technology is in hand to construct the 18 TF coils for SPARC.

      A history of achievement

      That LaBombard is part of the PSFC’s next fusion project is not unusual; that he is involved in designing, engineering, and testing the magnets is. Until 2018, when he led the R&D research team for one of the magnet designs being considered for SPARC, LaBombard’s 30-plus years of celebrated research had focused on other areas of the fusion question.

      As a graduate student, he gained early acclaim for the research he reported in his PhD thesis. Working on Alcator C, he made groundbreaking discoveries about the plasma physics in the “boundary” region of the tokamak, between the edge of the fusing core and the wall of the machine. With typical modesty, LaBombard credits some of his success to the fact that the topic was not well-studied, and that Alcator C provided measurements not possible on other machines.

      “People knew about the boundary, but nobody was really studying it in detail. On Alcator C, there were interesting phenomena, such as marfes [multifaceted asymmetric radiation from the edge], being detected for the first time. This pushed me to make boundary layer measurements in great detail that no one had ever seen before. It was all new territory, so I made a big splash.”

      That splash established him as a leading researcher in the field of boundary plasmas. After a two-year turn at the University of California at Los Angeles working on a plasma-wall test facility called PISCES, LaBombard, who grew up in New England, was happy to return to MIT to join the PSFC’s new Alcator C-Mod project.

      Over the next 28 years of C-Mod’s construction phase and operation, LaBombard continued to make groundbreaking contributions to understanding tokamak edge and divertor plasmas, and to design internal components that can survive the harsh conditions and provide plasma control — including C-Mod’s vertical target plate divertor and a unique divertor cryopump system. That experience led him to conceive of the “X-point target divertor” for handling extreme fusion power exhaust and to propose a national Advanced Divertor tokamak eXperiment (ADX) to test such ideas.

      All along, LaBombard’s true passion was in creating revolutionary diagnostics to unfold boundary layer physics and in guiding graduate students to do the same: an Omegatron, to measure impurity concentrations directly in the boundary plasma, resolved by charge-to-mass ratio; fast-scanning Langmuir-Mach probes to measure plasma flows; a Shoelace Antenna to provide insight into plasma fluctuations at the edge; the invention of a Mirror Langmuir Probe for the real-time measurements of plasma turbulence at high bandwidth.

      Switching sides

      His expertise established, he could have continued this focus on the edge of the plasma through collaborations with other laboratories and at the PSFC. Instead, he finds himself on the other side of the vacuum chamber, immersed in magnet design and technology. Challenged with finding an effective HTS magnet design for SPARC, he and his team were able to propose a winning strategy, one that seemed most likely to achieve the compact high field and high performance that PSFC tokamaks have been known for.

      LaBombard is stimulated by his new direction and excited about the upcoming test of the TFMC. His new role takes advantage of his physics background in electricity and magnetism. It also supports his passion for designing and building things, which he honed as high school apprentice to his machinist father and explored professionally building systems for Alcator C-Mod.

      “I view my principal role is to make sure the TF coil works electrically, the way it’s supposed to,” he says. “So it produces the magnetic field without damaging the coil.”

      A successful test would validate the understanding of how the new magnet technology works, and will prepare the team to build magnets for SPARC.

      Among those overseeing the hours of TFMC testing will be graduate students, current and former, reminding LaBombard of his own student days working on Alcator C, and of his years supervising students on Alcator C-Mod.

      “Those students were directly involved with Alcator C-Mod. They would jump in, make things happen — and as a team. This team spirit really enabled everyone to excel.

      “And looking to when SPARC was taking shape, you could see that across the board, from the new folks to the younger folks, they really got engaged by the spirit of Alcator — by recognition of the plasma performance that can be made possible by high magnetic fields.”

      He laughs as he looks to the past and to the future.

      “And they are taking it to SPARC.” More

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      in Energy

      Push to make supply chains more sustainable continues to gain momentum

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      Much of the effort to make businesses sustainable centers on their supply chains, which were severely disrupted during the Covid-19 pandemic. Yet, according to new research from the MIT Center for Transportation and Logistics (CTL), supply chain sustainability (SCS) investments hardly slowed, even as the pandemic raged.

      The finding, contained in the 2021 State of Supply Chain Sustainability report, puts companies on notice that they ignore the sustainability of their supply chains at their peril. This is particularly the case for enterprises with a low or moderate commitment to SCS, such as organizations classed as “Low Effort” and “Dreamer” in the new SCS Firm Typology that appears in the report for the first time. 

      The research also highlights the increasing pressure companies are under to devote resources to SCS. This pressure came from various stakeholders last year and suggests that sustainability in supply chains is a business trend, and not a fad.

      CTL publishes the 2021 State of Supply Chain Sustainability report in collaboration with the Council of Supply Chain Management Professionals (CSCMP), a leading professional membership association. This year’s report is sponsored by BlueYonder, C.H. Robinson, KPMG, Intel, and Sam’s Club.

      Sustainability efforts undaunted by Covid-19

      “We believe cooperation between sectors is vital to thoroughly understand the complexity and evolution of sustainability efforts more broadly,” says David Correll, CTL research scientist. “Our work with CSCMP and our sponsors helps us to embed this essential research and its findings within the context of the real-life practice of supply chain management.”

      The research included a large-scale international survey of supply chain professionals with over 2,400 respondents — more than double the number received for the previous report. The survey was conducted in late 2020. In addition, 21 in-depth executive interviews were completed, and relevant news items, social media content, and reports were analyzed for the report.

      More than 80 percent of survey respondents claimed the pandemic had no impact or increased their firms’ commitments to SCS: Eighty-three percent of the executives interviewed said that Covid-19 had either accelerated SCS activity or, at the very least, increased awareness and brought urgency to this growing field.

      The pressure to support sustainability in supply chains came from multiple sources, both internal and external, but increased the most among investors and industry associations. Internally, company executives were standout champions of SCS.

      Although there are many approaches to investing in SCS, interest in human rights protection and worker welfare, along with energy savings and renewable energy, increased significantly last year. Supplier development was the most common mechanism used by firms to deliver on their SCS promises.

      Increasing investment, some speed bumps

      Given the momentum behind SCS, the future will likely bring more investment in this increasingly important area of supply chain management. And practitioners — who bring deep domain expertise and well-rounded views of enterprises to the table — will become more influential as sustainability advocates.

      But there are some formidable obstacles to overcome, too. For example, it is notable that most of the momentum behind SCS appeared to come from large (1,000-plus employees) and very large (10,000-plus employees) companies covered by the research. Small- to medium-sized enterprises were far less committed, and more work is needed to bring them into the fold through a better understanding of the barriers they face.

      A broader concern is that more attention from stakeholders — notably consumers, investors, and regulators — will bring more scrutiny of firms’ SCS track records, and less tolerance of token efforts to make supply chains sustainable. Improved supply chain transparency and disclosure are critical to firms’ responses, the report suggests.

      Some high-profile issues, such as combating social injustices and climate change mitigation, will continue to stoke the pressure on companies to invest in meaningful SCS initiatives. It follows that the connection between companies’ SCS performance and their profitability is likely to strengthen over the next few years.

      Will companies follow through?

      As companies grapple with these issues, they will face some difficult decisions. For example, the chief operating officer of a consumer goods company interviewed for the report described operating through pandemic constraints as a “moral calculus” where some sustainability commitments had to be temporarily sacrificed to achieve others. Such a calculus will likely challenge many companies as they juggle their responses to SCS demands. A key question is to ascertain the degree to which companies’ recent net-zero commitments will translate into effective SCS actions over the next few years.

      The CTL and CSCMP research teams are laying the groundwork for the 2022 State of Supply Chain Sustainability report. This annual status report aims to help practitioners and the industry to make more effective and informed sustainability decisions. The questionnaire for next year’s report will open in September. More