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      Advancing the energy transition amidst global crises

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      “The past six years have been the warmest on the planet, and our track record on climate change mitigation is drastically short of what it needs to be,” said Robert C. Armstrong, MIT Energy Initiative (MITEI) director and the Chevron Professor of Chemical Engineering, introducing MITEI’s 15th Annual Research Conference.

      At the symposium, participants from academia, industry, and finance acknowledged the deepening difficulties of decarbonizing a world rocked by geopolitical conflicts and suffering from supply chain disruptions, energy insecurity, inflation, and a persistent pandemic. In spite of this grim backdrop, the conference offered evidence of significant progress in the energy transition. Researchers provided glimpses of a low-carbon future, presenting advances in such areas as long-duration energy storage, carbon capture, and renewable technologies.

      In his keynote remarks, Ernest J. Moniz, the Cecil and Ida Green Professor of Physics and Engineering Systems Emeritus, founding director of MITEI, and former U.S. secretary of energy, highlighted “four areas that have materially changed in the last year” that could shake up, and possibly accelerate, efforts to address climate change.

      Extreme weather seems to be propelling the public and policy makers of both U.S. parties toward “convergence … at least in recognition of the challenge,” Moniz said. He perceives a growing consensus that climate goals will require — in diminishing order of certainty — firm (always-on) power to complement renewable energy sources, a fuel (such as hydrogen) flowing alongside electricity, and removal of atmospheric carbon dioxide (CO2).

      Russia’s invasion of Ukraine, with its “weaponization of natural gas” and global energy impacts, underscores the idea that climate, energy security, and geopolitics “are now more or less recognized widely as one conversation.” Moniz pointed as well to new U.S. laws on climate change and infrastructure that will amplify the role of science and technology and “address the drive to technological dominance by China.”

      The rapid transformation of energy systems will require a comprehensive industrial policy, Moniz said. Government and industry must select and rapidly develop low-carbon fuels, firm power sources (possibly including nuclear power), CO2 removal systems, and long-duration energy storage technologies. “We will need to make progress on all fronts literally in this decade to come close to our goals for climate change mitigation,” he concluded.

      Global cooperation?

      Over two days, conference participants delved into many of the issues Moniz raised. In one of the first panels, scholars pondered whether the international community could forge a coordinated climate change response. The United States’ rift with China, especially over technology trade policies, loomed large.

      “Hatred of China is a bipartisan hobby and passion, but a blanket approach isn’t right, even for the sake of national security,” said Yasheng Huang, the Epoch Foundation Professor of Global Economics and Management at the MIT Sloan School of Management. “Although the United States and China working together would have huge effects for both countries, it is politically unpalatable in the short term,” said F. Taylor Fravel, the Arthur and Ruth Sloan Professor of Political Science and director of the MIT Security Studies Program. John E. Parsons, deputy director for research at the MIT Center for Energy and Environmental Policy Research, suggested that the United States should use this moment “to get our own act together … and start doing things,” such as building nuclear power plants in a cost-effective way.

      Debating carbon removal

      Several panels took up the matter of carbon emissions and the most promising technologies for contending with them. Charles Harvey, MIT professor of civil and environmental engineering, and Howard Herzog, a senior research engineer at MITEI, set the stage early, debating whether capturing carbon was essential to reaching net-zero targets.

      “I have no trouble getting to net zero without carbon capture and storage,” said David Keith, the Gordon McKay Professor of Applied Physics at Harvard University, in a subsequent roundtable. Carbon capture seems more risky to Keith than solar geoengineering, which involves injecting sulfur into the stratosphere to offset CO2 and its heat-trapping impacts.

      There are new ways of moving carbon from where it’s a problem to where it’s safer. Kripa K. Varanasi, MIT professor of mechanical engineering, described a process for modulating the pH of ocean water to remove CO2. Timothy Krysiek, managing director for Equinor Ventures, talked about construction of a 900-kilometer pipeline transporting CO2 from northern Germany to a large-scale storage site located in Norwegian waters 3,000 meters below the seabed. “We can use these offshore Norwegian assets as a giant carbon sink for Europe,” he said.

      A startup showcase featured additional approaches to the carbon challenge. Mantel, which received MITEI Seed Fund money, is developing molten salt material to capture carbon for long-term storage or for use in generating electricity. Verdox has come up with an electrochemical process for capturing dilute CO2 from the atmosphere.

      But while much of the global warming discussion focuses on CO2, other greenhouse gases are menacing. Another panel discussed measuring and mitigating these pollutants. “Methane has 82 times more warming power than CO2 from the point of emission,” said Desirée L. Plata, MIT associate professor of civil and environmental engineering. “Cutting methane is the strongest lever we have to slow climate change in the next 25 years — really the only lever.”

      Steven Hamburg, chief scientist and senior vice president of the Environmental Defense Fund, cautioned that emission of hydrogen molecules into the atmosphere can cause increases in other greenhouse gases such as methane, ozone, and water vapor. As researchers and industry turn to hydrogen as a fuel or as a feedstock for commercial processes, “we will need to minimize leakage … or risk increasing warming,” he said.

      Supply chains, markets, and new energy ventures

      In panels on energy storage and the clean energy supply chain, there were interesting discussions of challenges ahead. High-density energy materials such as lithium, cobalt, nickel, copper, and vanadium for grid-scale energy storage, electric vehicles (EVs), and other clean energy technologies, can be difficult to source. “These often come from water-stressed regions, and we need to be super thoughtful about environmental stresses,” said Elsa Olivetti, the Esther and Harold E. Edgerton Associate Professor in Materials Science and Engineering. She also noted that in light of the explosive growth in demand for metals such as lithium, recycling EVs won’t be of much help. “The amount of material coming back from end-of-life batteries is minor,” she said, until EVs are much further along in their adoption cycle.

      Arvind Sanger, founder and managing partner of Geosphere Capital, said that the United States should be developing its own rare earths and minerals, although gaining the know-how will take time, and overcoming “NIMBYism” (not in my backyard-ism) is a challenge. Sanger emphasized that we must continue to use “denser sources of energy” to catalyze the energy transition over the next decade. In particular, Sanger noted that “for every transition technology, steel is needed,” and steel is made in furnaces that use coal and natural gas. “It’s completely woolly-headed to think we can just go to a zero-fossil fuel future in a hurry,” he said.

      The topic of power markets occupied another panel, which focused on ways to ensure the distribution of reliable and affordable zero-carbon energy. Integrating intermittent resources such as wind and solar into the grid requires a suite of retail markets and new digital tools, said Anuradha Annaswamy, director of MIT’s Active-Adaptive Control Laboratory. Tim Schittekatte, a postdoc at the MIT Sloan School of Management, proposed auctions as a way of insuring consumers against periods of high market costs.

      Another panel described the very different investment needs of new energy startups, such as longer research and development phases. Hooisweng Ow, technology principal at Eni Next LLC Ventures, which is developing drilling technology for geothermal energy, recommends joint development and partnerships to reduce risk. Michael Kearney SM ’11, PhD ’19, SM ’19 is a partner at The Engine, a venture firm built by MIT investing in path-breaking technology to solve the toughest challenges in climate and other problems. Kearney believes the emergence of new technologies and markets will bring on “a labor transition on an order of magnitude never seen before in this country,” he said. “Workforce development is not a natural zone for startups … and this will have to change.”

      Supporting the global South

      The opportunities and challenges of the energy transition look quite different in the developing world. In conversation with Robert Armstrong, Luhut Binsar Pandjaitan, the coordinating minister for maritime affairs and investment of the Republic of Indonesia, reported that his “nation is rich with solar, wind, and energy transition minerals like nickel and copper,” but cannot on its own tackle developing renewable energy or reducing carbon emissions and improving grid infrastructure. “Education is a top priority, and we are very far behind in high technologies,” he said. “We need help and support from MIT to achieve our target,” he said.

      Technologies that could springboard Indonesia and other nations of the global South toward their climate goals are emerging in MITEI-supported projects and at young companies MITEI helped spawn. Among the promising innovations unveiled at the conference are new materials and designs for cooling buildings in hot climates and reducing the environmental costs of construction, and a sponge-like substance that passively sucks moisture out of the air to lower the energy required for running air conditioners in humid climates.

      Other ideas on the move from lab to market have great potential for industrialized nations as well, such as a computational framework for maximizing the energy output of ocean-based wind farms; a process for using ammonia as a renewable fuel with no CO2 emissions; long-duration energy storage derived from the oxidation of iron; and a laser-based method for unlocking geothermal steam to drive power plants. More

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      New materials could enable longer-lasting implantable batteries

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      For the last few decades, battery research has largely focused on rechargeable lithium-ion batteries, which are used in everything from electric cars to portable electronics and have improved dramatically in terms of affordability and capacity. But nonrechargeable batteries have seen little improvement during that time, despite their crucial role in many important uses such as implantable medical devices like pacemakers.

      Now, researchers at MIT have come up with a way to improve the energy density of these nonrechargeable, or “primary,” batteries. They say it could enable up to a 50 percent increase in useful lifetime, or a corresponding decrease in size and weight for a given amount of power or energy capacity, while also improving safety, with little or no increase in cost.

      The new findings, which involve substituting the conventionally inactive battery electrolyte with a material that is active for energy delivery, are reported today in the journal Proceedings of the National Academy of Sciences, in a paper by MIT Kavanaugh Postdoctoral Fellow Haining Gao, graduate student Alejandro Sevilla, associate professor of mechanical engineering Betar Gallant, and four others at MIT and Caltech.

      Replacing the battery in a pacemaker or other medical implant requires a surgical procedure, so any increase in the longevity of their batteries could have a significant impact on the patient’s quality of life, Gallant says. Primary batteries are used for such essential applications because they can provide about three times as much energy for a given size and weight as rechargeable batteries.

      That difference in capacity, Gao says, makes primary batteries “critical for applications where charging is not possible or is impractical.” The new materials work at human body temperature, so would be suitable for medical implants. In addition to implantable devices, with further development to make the batteries operate efficiently at cooler temperatures, applications could also include sensors in tracking devices for shipments, for example to ensure that temperature and humidity requirements for food or drug shipments are properly maintained throughout the shipping process. Or, they might be used in remotely operated aerial or underwater vehicles that need to remain ready for deployment over long periods.

      Pacemaker batteries typically last from five to 10 years, and even less if they require high-voltage functions such as defibrillation. Yet for such batteries, Gao says, the technology is considered mature, and “there haven’t been any major innovations in fundamental cell chemistries in the past 40 years.”

      The key to the team’s innovation is a new kind of electrolyte — the material that lies between the two electrical poles of the battery, the cathode and the anode, and allows charge carriers to pass through from one side to the other. Using a new liquid fluorinated compound, the team found that they could combine some of the functions of the cathode and the electrolyte in one compound, called a catholyte. This allows for saving much of the weight of typical primary batteries, Gao says.

      While there are other materials besides this new compound that could theoretically function in a similar catholyte role in a high-capacity battery, Gallant explains, those materials have lower inherent voltages that do not match those of the remainder of the material in a conventional pacemaker battery, a type known as CFx. Because the overall output from the battery can’t be more than that of the lesser of the two electrode materials,  the extra capacity would go to waste because of the voltage mismatch. But with the new material, “one of the key merits of our fluorinated liquids is that their voltage aligns very well with that of CFx,” Gallant says.

      In a conventional  CFx battery, the liquid electrolyte is essential because it allows charged particles to pass through from one electrode to the other. But “those electrolytes are actually chemically inactive, so they’re basically dead weight,” Gao says. This means about 50 percent of the battery’s key components, mainly the electrolyte, is inactive material. But in the new design with the fluorinated catholyte material, the amount of dead weight can be reduced to about 20 percent, she says.

      The new cells also provide safety improvements over other kinds of proposed chemistries that would use toxic and corrosive catholyte materials, which their formula does not, Gallant says. And preliminary tests have demonstrated a stable shelf life over more than a year, an important characteristic for primary batteries, she says.

      So far, the team has not yet experimentally achieved the full 50 percent improvement in energy density predicted by their analysis. They have demonstrated a 20 percent improvement, which in itself would be an important gain for some applications, Gallant says. The design of the cell itself has not yet been fully optimized, but the researchers can project the cell performance based on the performance of the active material itself. “We can see the projected cell-level performance when it’s scaled up can reach around 50 percent higher than the CFx cell,” she says. Achieving that level experimentally is the team’s next goal.

      Sevilla, a doctoral student in the mechanical engineering department, will be focusing on that work in the coming year. “I was brought into this project to try to understand some of the limitations of why we haven’t been able to attain the full energy density possible,” he says. “My role has been trying to fill in the gaps in terms of understanding the underlying reaction.”

      One big advantage of the new material, Gao says, is that it can easily be integrated into existing battery manufacturing processes, as a simple substitution of one material for another. Preliminary discussions with manufacturers confirm this potentially easy substitution, Gao says. The basic starting material, used for other purposes, has already been scaled up for production, she says, and its price is comparable to that of the materials currently used in CFx batteries. The cost of batteries using the new material is likely to be comparable to the existing batteries as well, she says. The team has already applied for a patent on the catholyte, and they expect that the medical applications are likely to be the first to be commercialized, perhaps with a full-scale prototype ready for testing in real devices within about a year.

      Further down the road, other applications could likely take advantage of the new materials as well, such as smart water or gas meters that can be read out remotely, or devices like EZPass transponders, increasing their usable lifetime, the researchers say. Power for drone aircraft or undersea vehicles would require higher power and so may take longer to be developed. Other uses could include batteries for equipment used at remote sites, such as drilling rigs for oil and gas, including devices sent down into the wells to monitor conditions.

      The team also included Gustavo Hobold, Aaron Melemed, and Rui Guo at MIT and Simon Jones at Caltech. The work was supported by MIT Lincoln Laboratory and the Army Research Office. More

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      in Security

      Pesticide innovation takes top prize at Collegiate Inventors Competition

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      On Oct. 12, MIT mechanical engineering alumnus Vishnu Jayaprakash SM ’19, PhD ’22 was named the first-place winner in the graduate category of the Collegiate Inventors Competition. The annual competition, which is organized by the National Inventors Hall of Fame, celebrates college and university student inventors. Jayaprakash won for his pesticide innovation AgZen-Cloak, which he developed while he was a student in the lab of Kripa Varanasi, a professor of mechanical engineering.

      Currently, only 2 percent of pesticide spray is retained by crops. Many crops are naturally water-repellent, causing pesticide-laden water to bounce off of them. Farmers are forced to over-spray significantly to ensure proper spray coverage on their crops. Not only does this waste expensive pesticides, but it also comes at an environmental cost.

      Runoff from pesticide treatment pollutes soil and nearby streams. Droplets can travel in the air, leading to illness and death in nearby populations. It is estimated that each year, pesticide pollution causes between 20,000 and 200,000 deaths, and up to 385 million acute illnesses like cancer, birth defects, and neurological conditions.   

      With his invention AgZen-Cloak, Jayaprakash has found a way to keep droplets of water containing pesticide from bouncing off crops by “cloaking” the droplets in a small amount of plant-derived oil. As a result, farmers could use just one-fifth the amount of spray, minimizing water waste and cost for farmers and eliminating airborne pollution and toxic runoff. It also improves pesticide retention, which can lead to higher crop yield.

      “By cloaking each droplet with a minute quantity of a plant-based oil, we promote water retention on even the most water-repellent plant surfaces,” says Jayaprakash. “AgZen-Cloak presents a universal, inexpensive, and environmentally sustainable way to prevent pesticide overuse and waste.”

      Farming is in Jayaprakash’s DNA. His family operates a 10-acre farm near Chennai, India, where they grow rice and mangoes. Upon joining the Varanasi Research Group as a graduate student, Jayaprakash was instantly drawn to Varanasi’s work on pesticides in agriculture.

      “Growing up, I would spray crops on my family farm wearing a backpack sprayer. So, I’ve always wanted to work on research that made farmer’s lives easier,” says Jayaprakash, who serves as CEO of the startup AgZen.

      Play video

      2022 World Food Day First Prize Winner – AgZen Cloak: Reducing Pesticide Pollution and Waste

      Helping droplets stick

      Varanasi and his lab at MIT work on what is known as interfacial phenomena — or the study of what happens when different phases come into contact and interact with one another. Understanding how a liquid interacts with a solid or how a liquid reacts to a certain gas has endless applications, which explains the diversity of the research Varanasi has conducted over the years. He and his team have developed solutions for everything from consumer product packaging to power plant emissions.

      In 2009, Varanasi gave a talk at the U.S. Department of Agriculture (USDA). There, he learned from the USDA just how big of a problem runoff from pesticide spray was for farmers around the world.
      A green cabbage leaf is treated with pesticide-laden water using conventional spraying. Image courtesy of AgZen.A green cabbage leaf is treated with pesticide-laden water using AgZen’s technology. By cloaking droplets in a tiny amount of plant-derived oil, the droplets stick to the leaf, minimizing over-spraying, waste, and pollution. Image courtesy of AgZen.He enlisted the help of then-graduate student Maher Damak SM ’15, PhD ’18 to apply their work in interfacial phenomena to pesticide sprays. Over the next several years, the Varanasi Research Group developed a technology that utilized electrically charged polymers to keep droplets from bouncing off hydrophobic surfaces. When droplets containing positively and negatively charged additives meet, their surface chemistry allows them to stick to a plant’s surface.

      Using polyelectrolytes, the researchers could reduce the amount of spray needed to cover a crop by tenfold in the lab. This motivated the Varanasi Research Group to pursue three years of field trials with various commercial growers around the world, where they were able to demonstrate significant savings for farmers.

      “We got fantastic feedback on our technology from farmers. We are really excited to change the paradigm for agriculture. Not only is it good for the environment, but we’ve heard from farmers that they love it. If we can put money back into farms, it helps society as a whole,” adds Varanasi.

      In response to the positive feedback, Varanasi and Jayaprakash co-founded startup AgZen in 2020. 

      When field testing their polyelectrolyte technology, Varanasi and Jayaprakash came up with the idea to explore the use of a fully plant-based material to help farmers achieve the same savings. 

      Cloaking droplets and engineering nozzles

      Jayaprakash found that by cloaking a small amount of plant-derived oil around a water droplet, droplets stick to plant surfaces that would typically repel water. After conducting many studies in the lab, he found that the oil only needs to make up 0.1 percent of a droplet’s total volume to stick to crops and provide total, uniform coverage.

      While his cloaking solution worked in the lab, Jayaprakash knew that to have a tangible impact in the real world he needed to find an easy, low-cost way for farmers to coat pesticide spray droplets in oil.

      Jayaprakash focused on spray nozzles. He developed a proprietary nozzle that coats each droplet with a small amount of oil as they are being formed. The nozzles can easily be added to any hose or farming equipment.

      “What we’ve done is figured out a smart way to cloak these droplets by using a very small quantity of oil on the outside of each drop. Because of that, we get this drastic improvement in performance that can really be a game-changer for farmers,” says Jayaprakash.

      In addition to improving pesticide retention in crops, the AgZen-Cloak solves a second problem. Since large droplets are prone to break apart and bounce off crops, historically, farmers have sprayed pesticide in tiny, mist-like droplets. These fine droplets are often carried by the wind, increasing pesticide pollution in nearby areas. 

      When AgZen-Cloak is used, the pesticide-laden droplets can be larger and still stick to crops. These larger droplets aren’t carried by the wind, decreasing the risk of pollution and minimizing the health impacts on local populations.  

      “We’re actually solving two problems with one solution. With the cloaking technology, we can spray much larger droplets that aren’t prone to wind drift and they can stick to the plant,” Jayaprakash adds.

      Bringing AgZen-Cloaks to farmers around the world

      This spring, Varanasi encouraged Jayaprakash to submit AgZen-Cloak to the Collegiate Inventors Competition. Out of hundreds of applications, Jayaprakash was one of 25 student inventors to be chosen as a finalist.

      On Oct. 12, Jayaprakash presented his technology to a panel of judges composed of National Inventors Hall of Fame inductees and U.S. Patent and Trademark Office officials. Meeting with such an illustrious group of inventors and officials left an impression on Jayaprakash.

      “These are people who have invented things that have changed the world. So, to get their feedback on what we’re doing was incredibly valuable,” he says. Jayaprakash received a $10,000 prize for being named the first-place graduate winner.

      As full-time CEO of AgZen, Jayaprakash is shifting focus to field testing and commercialization. He and the AgZen team have already conducted field testing across the world at locations including a Prosecco vineyard outside of Venice, a ranch in California, and Ward’s Berry Farm in Sharon, Massachusetts. The University of Massachusetts at Amherst’s vegetable extension program, led by their program director Susan Scheufele, recently concluded a field test that validated AgZen’s on-field performance.

      Two days after his win at the Collegiate Inventors Competition, Jayaprakash was named the first prize winner of the MIT Abdul Latif Jamel Water and Food Systems Lab World Food Day student video competition. Hours later, he flew across the country to attend an agricultural tech conference in California, eager to meet with farmers and discuss plans for rolling out AgZen’s innovations to farms everywhere. More

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      in Energy

      Ocean scientists measure sediment plume stirred up by deep-sea-mining vehicle

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      What will be the impact to the ocean if humans are to mine the deep sea? It’s a question that’s gaining urgency as interest in marine minerals has grown.

      The ocean’s deep-sea bed is scattered with ancient, potato-sized rocks called “polymetallic nodules” that contain nickel and cobalt — minerals that are in high demand for the manufacturing of batteries, such as for powering electric vehicles and storing renewable energy, and in response to factors such as increasing urbanization. The deep ocean contains vast quantities of mineral-laden nodules, but the impact of mining the ocean floor is both unknown and highly contested.

      Now MIT ocean scientists have shed some light on the topic, with a new study on the cloud of sediment that a collector vehicle would stir up as it picks up nodules from the seafloor.

      The study, appearing today in Science Advances, reports the results of a 2021 research cruise to a region of the Pacific Ocean known as the Clarion Clipperton Zone (CCZ), where polymetallic nodules abound. There, researchers equipped a pre-prototype collector vehicle with instruments to monitor sediment plume disturbances as the vehicle maneuvered across the seafloor, 4,500 meters below the ocean’s surface. Through a sequence of carefully conceived maneuvers. the MIT scientists used the vehicle to monitor its own sediment cloud and measure its properties.

      Their measurements showed that the vehicle created a dense plume of sediment in its wake, which spread under its own weight, in a phenomenon known in fluid dynamics as a “turbidity current.” As it gradually dispersed, the plume remained relatively low, staying within 2 meters of the seafloor, as opposed to immediately lofting higher into the water column as had been postulated.

      “It’s quite a different picture of what these plumes look like, compared to some of the conjecture,” says study co-author Thomas Peacock, professor of mechanical engineering at MIT. “Modeling efforts of deep-sea mining plumes will have to account for these processes that we identified, in order to assess their extent.”

      The study’s co-authors include lead author Carlos Muñoz-Royo, Raphael Ouillon, and Souha El Mousadik of MIT; and Matthew Alford of the Scripps Institution of Oceanography.

      Deep-sea maneuvers

      To collect polymetallic nodules, some mining companies are proposing to deploy tractor-sized vehicles to the bottom of the ocean. The vehicles would vacuum up the nodules along with some sediment along their path. The nodules and sediment would then be separated inside of the vehicle, with the nodules sent up through a riser pipe to a surface vessel, while most of the sediment would be discharged immediately behind the vehicle.

      Peacock and his group have previously studied the dynamics of the sediment plume that associated surface operation vessels may pump back into the ocean. In their current study, they focused on the opposite end of the operation, to measure the sediment cloud created by the collectors themselves.

      In April 2021, the team joined an expedition led by Global Sea Mineral Resources NV (GSR), a Belgian marine engineering contractor that is exploring the CCZ for ways to extract metal-rich nodules. A European-based science team, Mining Impacts 2, also conducted separate studies in parallel. The cruise was the first in over 40 years to test a “pre-prototype” collector vehicle in the CCZ. The machine, called Patania II, stands about 3 meters high, spans 4 meters wide, and is about one-third the size of what a commercial-scale vehicle is expected to be.

      While the contractor tested the vehicle’s nodule-collecting performance, the MIT scientists monitored the sediment cloud created in the vehicle’s wake. They did so using two maneuvers that the vehicle was programmed to take: a “selfie,” and a “drive-by.”

      Both maneuvers began in the same way, with the vehicle setting out in a straight line, all its suction systems turned on. The researchers let the vehicle drive along for 100 meters, collecting any nodules in its path. Then, in the “selfie” maneuver, they directed the vehicle to turn off its suction systems and double back around to drive through the cloud of sediment it had just created. The vehicle’s installed sensors measured the concentration of sediment during this “selfie” maneuver, allowing the scientists to monitor the cloud within minutes of the vehicle stirring it up.

      Play video

      A movie of the Patania II pre-prototype collector vehicle entering, driving through, and leaving the low-lying turbidity current plume as part of a selfie operation. For scale, the instrumentation post attached to the front of the vehicle reaches about 3m above the seabed. The movie is sped up by a factor of 20. Credit: Global Sea Mineral Resources

      For the “drive-by” maneuver, the researchers placed a sensor-laden mooring 50 to 100 meters from the vehicle’s planned tracks. As the vehicle drove along collecting nodules, it created a plume that eventually spread past the mooring after an hour or two. This “drive-by” maneuver enabled the team to monitor the sediment cloud over a longer timescale of several hours, capturing the plume evolution.

      Out of steam

      Over multiple vehicle runs, Peacock and his team were able to measure and track the evolution of the sediment plume created by the deep-sea-mining vehicle.

      “We saw that the vehicle would be driving in clear water, seeing the nodules on the seabed,” Peacock says. “And then suddenly there’s this very sharp sediment cloud coming through when the vehicle enters the plume.”

      From the selfie views, the team observed a behavior that was predicted by some of their previous modeling studies: The vehicle stirred up a heavy amount of sediment that was dense enough that, even after some mixing with the surrounding water, it generated a plume that behaved almost as a separate fluid, spreading under its own weight in what’s known as a turbidity current.

      “The turbidity current spreads under its own weight for some time, tens of minutes, but as it does so, it’s depositing sediment on the seabed and eventually running out of steam,” Peacock says. “After that, the ocean currents get stronger than the natural spreading, and the sediment transitions to being carried by the ocean currents.”

      By the time the sediment drifted past the mooring, the researchers estimate that 92 to 98 percent of the sediment either settled back down or remained within 2 meters of the seafloor as a low-lying cloud. There is, however, no guarantee that the sediment always stays there rather than drifting further up in the water column. Recent and future studies by the research team are looking into this question, with the goal of consolidating understanding for deep-sea mining sediment plumes.

      “Our study clarifies the reality of what the initial sediment disturbance looks like when you have a certain type of nodule mining operation,” Peacock says. “The big takeaway is that there are complex processes like turbidity currents that take place when you do this kind of collection. So, any effort to model a deep-sea-mining operation’s impact will have to capture these processes.”

      “Sediment plumes produced by deep-seabed mining are a major concern with regards to environmental impact, as they will spread over potentially large areas beyond the actual site of mining and affect deep-sea life,” says Henko de Stigter, a marine geologist at the Royal Netherlands Institute for Sea Research, who was not involved in the research. “The current paper provides essential insight in the initial development of these plumes.”

      This research was supported, in part, by the National Science Foundation, ARPA-E, the 11th Hour Project, the Benioff Ocean Initiative, and Global Sea Mineral Resources. The funders had no role in any aspects of the research analysis, the research team states. More

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      Passive cooling system could benefit off-grid locations

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      As the world gets warmer, the use of power-hungry air conditioning systems is projected to increase significantly, putting a strain on existing power grids and bypassing many locations with little or no reliable electric power. Now, an innovative system developed at MIT offers a way to use passive cooling to preserve food crops and supplement conventional air conditioners in buildings, with no need for power and only a small need for water.

      The system, which combines radiative cooling, evaporative cooling, and thermal insulation in a slim package that could resemble existing solar panels, can provide up to about 19 degrees Fahrenheit (9.3 degrees Celsius) of cooling from the ambient temperature, enough to permit safe food storage for about 40 percent longer under very humid conditions. It could triple the safe storage time under dryer conditions.

      The findings are reported today in the journal Cell Reports Physical Science, in a paper by MIT postdoc Zhengmao Lu, Arny Leroy PhD ’21, professors Jeffrey Grossman and Evelyn Wang, and two others. While more research is needed in order to bring down the cost of one key component of the system, the researchers say that eventually such a system could play a significant role in meeting the cooling needs of many parts of the world where a lack of electricity or water limits the use of conventional cooling systems.

      The system cleverly combines previous standalone cooling designs that each provide limited amounts of cooling power, in order to produce significantly more cooling overall — enough to help reduce food losses from spoilage in parts of the world that are already suffering from limited food supplies. In recognition of that potential, the research team has been partly supported by MIT’s Abdul Latif Jameel Water and Food Systems Lab.

      “This technology combines some of the good features of previous technologies such as evaporative cooling and radiative cooling,” Lu says. By using this combination, he says, “we show that you can achieve significant food life extension, even in areas where you have high humidity,” which limits the capabilities of conventional evaporative or radiative cooling systems.

      In places that do have existing air conditioning systems in buildings, the new system could be used to significantly reduce the load on these systems by sending cool water to the hottest part of the system, the condenser. “By lowering the condenser temperature, you can effectively increase the air conditioner efficiency, so that way you can potentially save energy,” Lu says.

      Other groups have also been pursuing passive cooling technologies, he says, but “by combining those features in a synergistic way, we are now able to achieve high cooling performance, even in high-humidity areas where previous technology generally cannot perform well.”

      The system consists of three layers of material, which together provide cooling as water and heat pass through the device. In practice, the device could resemble a conventional solar panel, but instead of putting out electricity, it would directly provide cooling, for example by acting as the roof of a food storage container. Or, it could be used to send chilled water through pipes to cool parts of an existing air conditioning system and improve its efficiency. The only maintenance required is adding water for the evaporation, but the consumption is so low that this need only be done about once every four days in the hottest, driest areas, and only once a month in wetter areas.

      The top layer is an aerogel, a material consisting mostly of air enclosed in the cavities of a sponge-like structure made of polyethylene. The material is highly insulating but freely allows both water vapor and infrared radiation to pass through. The evaporation of water (rising up from the layer below) provides some of the cooling power, while the infrared radiation, taking advantage of the extreme transparency of Earth’s atmosphere at those wavelengths, radiates some of the heat straight up through the air and into space — unlike air conditioners, which spew hot air into the immediate surrounding environment.

      Below the aerogel is a layer of hydrogel — another sponge-like material, but one whose pore spaces filled with water rather than air. It’s similar to material currently used commercially for products such as cooling pads or wound dressings. This provides the water source for evaporative cooling, as water vapor forms at its surface and the vapor passes up right through the aerogel layer and out to the environment.

      Below that, a mirror-like layer reflects any incoming sunlight that has reached it, sending it back up through the device rather than letting it heat up the materials and thus reducing their thermal load. And the top layer of aerogel, being a good insulator, is also highly solar-reflecting, limiting the amount of solar heating of the device, even under strong direct sunlight.

      “The novelty here is really just bringing together the radiative cooling feature, the evaporative cooling feature, and also the thermal insulation feature all together in one architecture,” Lu explains. The system was tested, using a small version, just 4 inches across, on the rooftop of a building at MIT, proving its effectiveness even during suboptimal weather conditions, Lu says, and achieving 9.3 C of cooling (18.7 F).

      “The challenge previously was that evaporative materials often do not deal with solar absorption well,” Lu says. “With these other materials, usually when they’re under the sun, they get heated, so they are unable to get to high cooling power at the ambient temperature.”

      The aerogel material’s properties are a key to the system’s overall efficiency, but that material at present is expensive to produce, as it requires special equipment for critical point drying (CPD) to remove solvents slowly from the delicate porous structure without damaging it. The key characteristic that needs to be controlled to provide the desired characteristics is the size of the pores in the aerogel, which is made by mixing the polyethylene material with solvents, allowing it to set like a bowl of Jell-O, and then getting the solvents out of it. The research team is currently exploring ways of either making this drying process more inexpensive, such as by using freeze-drying, or finding alternative materials that can provide the same insulating function at lower cost, such as membranes separated by an air gap.

      While the other materials used in the system are readily available and relatively inexpensive, Lu says, “the aerogel is the only material that’s a product from the lab that requires further development in terms of mass production.” And it’s impossible to predict how long that development might take before this system can be made practical for widespread use, he says.

      The research team included Lenan Zhang of MIT’s Department of Mechanical Engineering and Jatin Patil of the Department of Materials Science and Engineering. More

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      A lasting — and valuable — legacy

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      Betar Gallant, MIT associate professor and Class of 1922 Career Development Chair in Mechanical Engineering, grew up in a curious, independently minded family. Her mother had multiple jobs over the years, including in urban planning and in the geospatial field. Her father, although formally trained in English, read textbooks of all kinds from cover to cover, taught himself numerous technical fields including engineering, and worked successfully in them. When Gallant was very young, she and her father did science experiments in the basement.

      It wasn’t until she was in her teenage years, though, that she says she got drawn into science. Her father, who had fallen ill five years before, died when Gallant was 16, and while grieving, “when I was missing him the most,” she started to look at what had captivated her father.

      “I started to take a deeper interest in the things he had spent his life working on as a way to feel closer to him in his absence,” Gallant says. “I spent a few long months one summer looking through some of the things he had worked on, and found myself reading physics textbooks. That was enough, and I was hooked.”

      The love for independently finding and understanding solutions, that she had apparently inherited from her parents, eventually took her to the professional love of her life: electrochemistry.

      As an undergraduate at MIT, Gallant did an Undergraduate Research Opportunities Program project with Professor Yang Shao-Horn’s research group that went from her sophomore year through her senior thesis. This was Gallant’s first official exposure to electrochemistry.

      “When I met Yang, she showed me very quickly how challenging and enriching electrochemistry can be, and there was real conviction and excitement in how she and her group members talked about research,” Gallant says. “It was totally eye-opening, and I’m fortunate that she was a (relatively rare) electrochemist in a mechanical engineering department, or else I likely would not have been able to go down that road.”

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      Gallant earned three degrees at MIT (’08, SM ’10, and PhD ’13). Before joining the MIT faculty in 2016, she was a Kavli Nanoscience Institute Prize Postdoctoral Fellow at Caltech in the Division of Chemistry and Chemical Engineering.

      Her passion for electrochemistry is enormous. “Electrons are just dazzling — they power so much of our everyday world, and are the key to a renewable future,” she says, explaining that despite electrons’ amazing potential, isolated electrons cannot be stored and produced on demand, because “nature doesn’t allow excessive amounts of charge imbalances to accumulate.”

      Electrons can, however, be stored on molecules, in bonds and in metal ions or nonmetal centers that are able to lose and gain electrons — as long as positive charge transfers occur to accommodate the electrons.

      “Here’s where chemistry rears its head,” Gallant says. “What types of molecules or materials can behave in this way? How do we store as much charge as possible while making the weight and volume as low as possible?”

      Gallant points out that early battery developers using lithium and ions built a technology that “has arguably shaped our modern world more than any other.

      “If you look at some early papers, the concepts of how a lithium-ion battery or a lithium metal anode worked were sketched out by hand — they had been deduced to be true, before the field even had the tools to prove all the mechanisms were actually occurring — yet even now, those ideas are still turning out to be right!”

      Gallant says, “that’s because if you truly understand the basic principles of electrochemistry, you can start to intuit how systems will behave. Once you can do that, you can really begin to engineer better materials and devices.”

      Truly her father’s daughter, Gallant’s emphasis is on independently finding solutions.

      “Ultimately, it’s a race to have the best mental models,” she says. “A great lab and lots of funding and personnel to run it are very nice, but the most valuable tools in the toolbox are solid mental models and a way of thinking about electrochemistry, which is actually very personalized depending on the researcher.”

      She says one project with immediate impact that’s coming out of her Gallant Energy and Carbon Conversion Lab relates to primary (non-rechargeable) battery work that she and her team are working to commercialize. It involves injecting new electrochemically active electrolytes into leading high-energy batteries as they’re being assembled. Replacing a conventional electrolyte with the new chemistry decreases the normally inactive weight of the battery and boosts the energy substantially, Gallant says. One important application of such batteries would be for medical devices such as pacemakers.

      “If you can extend lifetime, you’re talking about longer times between invasive replacement surgeries, which really affects patient quality of life,” she says.

      Gallant’s team is also leading efforts to enable higher-energy rechargeable lithium-ion batteries for electric vehicles. Key to a step-change in energy, and therefore driving range, is to use a lithium metal anode in place of graphite. Lithium metal is highly reactive, however, with all battery electrolytes, and its interface needs to be stabilized in ways that still elude researchers. Gallant’s team is developing design guidelines for such interfaces, and for next-generation electrolytes to form and sustain these interfaces. Gallant says that applying the technology to that purpose and commercializing it would be “a bit longer-term, but I believe this change to lithium anodes will happen, and it’s just a matter of when.”

      About six years ago, when Gallant founded her lab, she and her team started introducing carbon dioxide into batteries as a way to experiment with electrochemical conversion of the greenhouse gas. She says they realized that batteries do not present the best practical technology to mitigate CO2, but their experimentation did open up new paths to carbon capture and conversion. “That work allowed us to think creatively, and we started to realize that there is tremendous potential to manipulate CO2 reactions by carefully designing the electrochemical environment.” That led her team to the idea of conducting electrochemical transformations on CO2 from a captured state bound to a capture sorbent, replacing the energy-intense regeneration step of today’s capture processes and streamlining the process.  

      “Now we’re seeing other researchers working on that, too, and taking this idea in exciting directions — it’s a very challenging and very rich topic,” she says.

      Gallant has won awards including an MIT Bose Fellowship, the Army Research Office Young Investigator Award, the Scialog Fellowship in Energy Storage and in Negative Emissions Science, a CAREER award from the National Science Foundation, the Ruth and Joel Spira Award for Distinguished Teaching at MIT, the Electrochemical Society (ECS) Battery Division Early Career award, and an ECS-Toyota Young Investigator Award.

      These days, Gallant does some of her best thinking while brainstorming with her research group members and with her husband, who is also an academic. She says being a professor at MIT means she has “a queue of things to think about,” but she sometimes gets awarded with a revelation.

      “My brain gets overloaded because I can’t think through everything instantaneously; ideas have to get in line! So there’s a lot going on in the background at all times,” she say. “I don’t know how it works, but sometimes I’ll be going for a walk or doing something else, and an idea breaks through. Those are the fun ones.” More

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      in Energy

      Computing for the health of the planet

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      The health of the planet is one of the most important challenges facing humankind today. From climate change to unsafe levels of air and water pollution to coastal and agricultural land erosion, a number of serious challenges threaten human and ecosystem health.

      Ensuring the health and safety of our planet necessitates approaches that connect scientific, engineering, social, economic, and political aspects. New computational methods can play a critical role by providing data-driven models and solutions for cleaner air, usable water, resilient food, efficient transportation systems, better-preserved biodiversity, and sustainable sources of energy.

      The MIT Schwarzman College of Computing is committed to hiring multiple new faculty in computing for climate and the environment, as part of MIT’s plan to recruit 20 climate-focused faculty under its climate action plan. This year the college undertook searches with several departments in the schools of Engineering and Science for shared faculty in computing for health of the planet, one of the six strategic areas of inquiry identified in an MIT-wide planning process to help focus shared hiring efforts. The college also undertook searches for core computing faculty in the Department of Electrical Engineering and Computer Science (EECS).

      The searches are part of an ongoing effort by the MIT Schwarzman College of Computing to hire 50 new faculty — 25 shared with other academic departments and 25 in computer science and artificial intelligence and decision-making. The goal is to build capacity at MIT to help more deeply infuse computing and other disciplines in departments.

      Four interdisciplinary scholars were hired in these searches. They will join the MIT faculty in the coming year to engage in research and teaching that will advance physical understanding of low-carbon energy solutions, Earth-climate modeling, biodiversity monitoring and conservation, and agricultural management through high-performance computing, transformational numerical methods, and machine-learning techniques.

      “By coordinating hiring efforts with multiple departments and schools, we were able to attract a cohort of exceptional scholars in this area to MIT. Each of them is developing and using advanced computational methods and tools to help find solutions for a range of climate and environmental issues,” says Daniel Huttenlocher, dean of the MIT Schwarzman College of Computing and the Henry Warren Ellis Professor of Electrical Engineering and Computer Science. “They will also help strengthen cross-departmental ties in computing across an important, critical area for MIT and the world.”

      “These strategic hires in the area of computing for climate and the environment are an incredible opportunity for the college to deepen its academic offerings and create new opportunity for collaboration across MIT,” says Anantha P. Chandrakasan, dean of the MIT School of Engineering and the Vannevar Bush Professor of Electrical Engineering and Computer Science. “The college plays a pivotal role in MIT’s overarching effort to hire climate-focused faculty — introducing the critical role of computing to address the health of the planet through innovative research and curriculum.”

      The four new faculty members are:

      Sara Beery will join MIT as an assistant professor in the Faculty of Artificial Intelligence and Decision-Making in EECS in September 2023. Beery received her PhD in computing and mathematical sciences at Caltech in 2022, where she was advised by Pietro Perona. Her research focuses on building computer vision methods that enable global-scale environmental and biodiversity monitoring across data modalities, tackling real-world challenges including strong spatiotemporal correlations, imperfect data quality, fine-grained categories, and long-tailed distributions. She partners with nongovernmental organizations and government agencies to deploy her methods in the wild worldwide and works toward increasing the diversity and accessibility of academic research in artificial intelligence through interdisciplinary capacity building and education.

      Priya Donti will join MIT as an assistant professor in the faculties of Electrical Engineering and Artificial Intelligence and Decision-Making in EECS in academic year 2023-24. Donti recently finished her PhD in the Computer Science Department and the Department of Engineering and Public Policy at Carnegie Mellon University, co-advised by Zico Kolter and Inês Azevedo. Her work focuses on machine learning for forecasting, optimization, and control in high-renewables power grids. Specifically, her research explores methods to incorporate the physics and hard constraints associated with electric power systems into deep learning models. Donti is also co-founder and chair of Climate Change AI, a nonprofit initiative to catalyze impactful work at the intersection of climate change and machine learning that is currently running through the Cornell Tech Runway Startup Postdoc Program.

      Ericmoore Jossou will join MIT as an assistant professor in a shared position between the Department of Nuclear Science and Engineering and the faculty of electrical engineering in EECS in July 2023. He is currently an assistant scientist at the Brookhaven National Laboratory, a U.S. Department of Energy-affiliated lab that conducts research in nuclear and high energy physics, energy science and technology, environmental and bioscience, nanoscience, and national security. His research at MIT will focus on understanding the processing-structure-properties correlation of materials for nuclear energy applications through advanced experiments, multiscale simulations, and data science. Jossou obtained his PhD in mechanical engineering in 2019 from the University of Saskatchewan.

      Sherrie Wang will join MIT as an assistant professor in a shared position between the Department of Mechanical Engineering and the Institute for Data, Systems, and Society in academic year 2023-24. Wang is currently a Ciriacy-Wantrup Postdoctoral Fellow at the University of California at Berkeley, hosted by Solomon Hsiang and the Global Policy Lab. She develops machine learning for Earth observation data. Her primary application areas are improving agricultural management and forecasting climate phenomena. She obtained her PhD in computational and mathematical engineering from Stanford University in 2021, where she was advised by David Lobell. More

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      MIT students contribute to success of historic fusion experiment

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      For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition in a laboratory, a grand challenge of the 21st century. The High-Energy-Density Physics (HEDP) group at MIT’s Plasma Science and Fusion Center has focused on an approach called inertial confinement fusion (ICF), which uses lasers to implode a pellet of fuel in a quest for ignition. This group, including nine former and current MIT students, was crucial to an historic ICF ignition experiment performed in 2021; the results were published on the anniversary of that success.

      On Aug. 8, 2021, researchers at the National Ignition Facility (NIF), Lawrence Livermore National Laboratory (LLNL), used 192 laser beams to illuminate the inside of a tiny gold cylinder encapsulating a spherical capsule filled with deuterium-tritium fuel in their quest to produce significant fusion energy. Although researchers had followed this process many times before, using different parameters, this time the ensuing implosion produced an historic fusion yield of 1.37 megaJoules, as measured by a suite of neutron diagnostics. These included the MIT-developed and analyzed Magnetic Recoil Spectrometer (MRS). This result was published in Physical Review Letters on Aug. 8, the one-year anniversary of the ground-breaking development, unequivocally indicating that the first controlled fusion experiment reached ignition.

      Governed by the Lawson criterion, a plasma ignites when the internal fusion heating power is high enough to overcome the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop that very rapidly increases the plasma temperature. In the case of ICF, ignition is a state where the fusion plasma can initiate a “fuel burn propagation” into the surrounding dense and cold fuel, enabling the possibility of high fusion-energy gain.

      “This historic result certainly demonstrates that the ignition threshold is a real concept, with well-predicted theoretical calculations, and that a fusion plasma can be ignited in a laboratory” says HEDP Division Head Johan Frenje.

      The HEDP division has contributed to the success of the ignition program at the NIF for more than a decade by providing and using a dozen diagnostics, implemented by MIT PhD students and staff, which have been critical for assessing the performance of an implosion. The hundreds of co-authors on the paper attest to the collaborative effort that went into this milestone. MIT’s contributors included the only student co-authors.

      “The students are responsible for implementing and using a diagnostic to obtain data important to the ICF program at the NIF, says Frenje. “Being responsible for running a diagnostic at the NIF has allowed them to actively participate in the scientific dialog and thus get directly exposed to cutting-edge science.”

      Students involved from the MIT Department of Physics were Neel Kabadi, Graeme Sutcliffe, Tim Johnson, Jacob Pearcy, and Ben Reichelt; students from the Department of Nuclear Science and Engineering included Brandon Lahmann, Patrick Adrian, and Justin Kunimune.

      In addition, former student Alex Zylstra PhD ’15, now a physicist at LLNL, was the experimental lead of this record implosion experiment. More