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      Robert Armstrong: A lifetime at the forefront of chemical engineering research and education

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      Robert C. Armstrong, the Chevron Professor of Chemical Engineering who has been the director of the MIT Energy Initiative (MITEI) since 2013 and part of MITEI’s leadership team since its inception in 2007, has announced that he will retire effective June 30. At that time he will have completed 50 years on the MIT faculty.  

      Armstrong plans to continue to work at 10 percent capacity, focusing on research projects on which he serves as principal investigator and also advising a number of graduate students.

      “Working at MIT has been a great honor and privilege for me,” says Armstrong. “Nowhere else can I imagine having had the opportunity to work with such exceptional students and colleagues and to have a ‘job’ that makes me want to get up every day to see what I can do to help humanity with its great challenges.”

      Armstrong joined the founding MITEI leadership team with Ernest Moniz, now the Cecil and Ida Green Professor of Physics and Engineering Systems emeritus and special advisor to the MIT president. When Moniz left MIT in 2013 to become U.S. secretary of energy, Armstrong was named MITEI director.

      “MITEI has enabled us to leverage MIT’s great talent base to make significant advances in energy research, education, and outreach,” says Armstrong. “This is an incredibly important and exciting time in energy, and there is much to be done in envisioning and implementing an energy transition that mitigates the worst impacts of climate change, provides energy justly and equitably to those around the world without access or with inadequate access, and improves security of energy supply. I have been honored to do this work with amazing colleagues at MITEI and throughout MIT, and I will be cheering that team on, as it races to reach net-zero greenhouse gas emissions by 2050.”

      MIT Vice President for Research Maria Zuber will form a search committee to select the new MITEI director. Zuber has worked closely with Armstrong since she became vice president for research in 2012.

      “Anyone who knows Bob knows that he is soft-spoken, but a person of deep conviction,” says Zuber. “He is a master of complexity, an admired educator, a respected leader, and a terrific colleague. During his decade as director, Bob has focused the MIT Energy Initiative on the urgent, daunting challenge of transforming the global energy system to respond to the climate crisis. In the last couple of years, Bob led the creation of MITEI’s Future Energy Systems Center, reflecting his keen understanding that an effective climate response requires integrated analysis and a systems approach — there is no one-fix-all solution. I congratulate Bob on a remarkable career, and I thank him for his half-century of dedicated service to MIT.”

      Armstrong joined the MIT faculty in 1973 after earning his doctorate in chemical engineering from the University of Wisconsin at Madison. A native of Louisiana, he earned his undergraduate degree in chemical engineering from Georgia Tech. He served as chair of the MIT Department of Chemical Engineering from 1996 until joining MITEI in 2007. 

      “In his 50 years at MIT, Bob has been a truly dedicated educator, researcher, and leader in our department, the Institute, and the field of chemical engineering,” says Paula T. Hammond, Institute professor and the head of the MIT Department of Chemical Engineering — a successor to Armstrong in that role. “During his time as head, he expertly expanded the breadth and depth of the department’s research and academics while maintaining its high level of excellence. He has served as a thoughtful and proactive mentor to so many of our faculty members, as well as a dedicated teacher and advocate for modernizing chemical engineering curriculum. We are extremely fortunate to have profited from his scholarship and leadership over the past several decades and will continue to benefit thanks to his vision and work toward the future of chemical engineering and energy.”

      In 2008, Armstrong was elected a member of the National Academy of Engineering, based on his research into non-Newtonian fluid mechanics, his leadership in chemical engineering education, and his co-authoring of influential chemical engineering textbooks. He became a fellow of the American Academy of Arts and Sciences in 2020.

      He received the 2006 Bingham Medal from The Society of Rheology, which is devoted to the study of the science of deformation and flow of matter, as well as the Founders Award (2020), the Warren K. Lewis Award (2006), and the Professional Progress Award (1992), all from the American Institute of Chemical Engineers. More

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      Exploring new sides of climate and sustainability research

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      When the MIT Climate and Sustainability Consortium (MCSC) launched its Climate and Sustainability Scholars Program in fall 2022, the goal was to offer undergraduate students a unique way to develop and implement research projects with the strong support of each other and MIT faculty. Now into its second semester, the program is underscoring the value of fostering this kind of network — a community with MIT students at its core, exploring their diverse interests and passions in the climate and sustainability realms.Inspired by MIT’s successful SuperUROP [Undergraduate Research Opportunities Program], the yearlong MCSC Climate and Sustainability Scholars Program includes a classroom component combined with experiential learning opportunities and mentorship, all centered on climate and sustainability topics.“Harnessing the innovation, passion, and expertise of our talented students is critical to MIT’s mission of tackling the climate crisis,” says Anantha P. Chandrakasan, dean of the School of Engineering, Vannevar Bush Professor of Electrical Engineering and Computer Science, and chair of the MCSC. “The program is helping train students from a variety of disciplines and backgrounds to be effective leaders in climate and sustainability-focused roles in the future.”

      “What we found inspiring about MIT’s existing SuperUROP program was how it provides students with the guidance, training, and resources they need to investigate the world’s toughest problems,” says Elsa Olivetti, the Esther and Harold E. Edgerton Associate Professor in Materials Science and Engineering and MCSC co-director. “This incredible level of support and mentorship encourages students to think and explore in creative ways, make new connections, and develop strategies and solutions that propel their work forward.”The first and current cohort of Climate and Sustainability Scholars consists of 19 students, representing MIT’s School of Engineering, MIT Schwarzman College of Computing, School of Science, School of Architecture and Planning, and MIT Sloan School of Management. These students are learning new perspectives, approaches, and angles in climate and sustainability — from each other, MIT faculty, and industry professionals.Projects with real-world applicationsStudents in the program work directly with faculty and principal investigators across MIT to develop their research projects focused on a large scope of sustainability topics.

      “This broad scope is important,” says Desirée Plata, MIT’s Gilbert W. Winslow Career Development Professor in Civil and Environmental Engineering, “because climate and sustainability solutions are needed in every facet of society. For a long time, people were searching for a ‘silver bullet’ solution to the climate change problems, but we didn’t get to this point with a single technological decision. This problem was created across a spectrum of sociotechnological activities, and fundamentally different thinking across a spectrum of solutions is what’s needed to move us forward. MCSC students are working to provide those solutions.”

      Undergraduate student and physics major M. (MG) Geogdzhayeva is working with Raffaele Ferrari, Cecil and Ida Green Professor of Oceanography in the Department of Earth, Atmospheric and Planetary Sciences, and director of the Program in Atmospheres, Oceans, and Climate, on their project “Using Continuous Time Markov Chains to Project Extreme Events under Climate.” Geogdzhayeva’s research supports the Flagship Climate Grand Challenges project that Ferrari is leading along with Professor Noelle Eckley Selin.

      “The project I am working on has a similar approach to the Climate Grand Challenges project entitled “Bringing computation to the climate challenge,” says Geogdzhayeva. “I am designing an emulator for climate extremes. Our goal is to boil down climate information to what is necessary and to create a framework that can deliver specific information — in order to develop valuable forecasts. As someone who comes from a physics background, the Climate and Sustainability Scholars Program has helped me think about how my research fits into the real world, and how it could be implemented.”

      Investigating technology and stakeholders

      Within technology development, Jade Chongsathapornpong, also a physics major, is diving into photo-modulated catalytic reactions for clean energy applications. Chongsathapornpong, who has worked with the MCSC on carbon capture and sequestration through the Undergraduate Research Opportunities Program (UROP), is now working with Harry Tuller, MIT’s R.P. Simmons Professor of Ceramics and Electronic Materials. Louise Anderfaas, majoring in materials science and engineering, is also working with Tuller on her project “Robust and High Sensitivity Detectors for Exploration of Deep Geothermal Wells.”Two other students who have worked with the MCSC through UROP include Paul Irvine, electrical engineering and computer science major, who is now researching American conservatism’s current relation to and views about sustainability and climate change, and Pamela Duke, management major, now investigating the use of simulation tools to empower industrial decision-makers around climate change action.Other projects focusing on technology development include the experimental characterization of poly(arylene ethers) for energy-efficient propane/propylene separations by Duha Syar, who is a chemical engineering major and working with Zachary Smith, the Robert N. Noyce Career Development Professor of Chemical Engineering; developing methods to improve sheet steel recycling by Rebecca Lizarde, who is majoring in materials science and engineering; and ion conduction in polymer-ceramic composite electrolytes by Melissa Stok, also majoring in materials science and engineering.

      Melissa Stok, materials science and engineering major, during a classroom discussion.

      Photo: Andrew Okyere

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      “My project is very closely connected to developing better Li-Ion batteries, which are extremely important in our transition towards clean energy,” explains Stok, who is working with Bilge Yildiz, MIT’s Breene M. Kerr (1951) Professor of Nuclear Science and Engineering. “Currently, electric cars are limited in their range by their battery capacity, so working to create more effective batteries with higher energy densities and better power capacities will help make these cars go farther and faster. In addition, using safer materials that do not have as high of an environmental toll for extraction is also important.” Claire Kim, a chemical engineering major, is focusing on batteries as well, but is honing in on large form factor batteries more relevant for grid-scale energy storage with Fikile Brushett, associate professor of chemical engineering.Some students in the program chose to focus on stakeholders, which, when it comes to climate and sustainability, can range from entities in business and industry to farmers to Indigenous people and their communities. Shivani Konduru, an electrical engineering and computer science major, is exploring the “backfire effects” in climate change communication, focusing on perceptions of climate change and how the messenger may change outcomes, and Einat Gavish, mathematics major, on how different stakeholders perceive information on driving behavior.Two students are researching the impact of technology on local populations. Anushree Chaudhuri, who is majoring in urban studies and planning, is working with Lawrence Susskind, Ford Professor of Urban and Environmental Planning, on community acceptance of renewable energy siting, and Amelia Dogan, also an urban studies and planning major, is working with Danielle Wood, assistant professor of aeronautics and astronautics and media arts and sciences, on Indigenous data sovereignty in environmental contexts.

      “I am interviewing Indigenous environmental activists for my project,” says Dogan. “This course is the first one directly related to sustainability that I have taken, and I am really enjoying it. It has opened me up to other aspects of climate beyond just the humanity side, which is my focus. I did MIT’s SuperUROP program and loved it, so was excited to do this similar opportunity with the climate and sustainability focus.”

      Other projects include in-field monitoring of water quality by Dahlia Dry, a physics major; understanding carbon release and accrual in coastal wetlands by Trinity Stallins, an urban studies and planning major; and investigating enzyme synthesis for bioremediation by Delight Nweneka, an electrical engineering and computer science major, each linked to the MCSC’s impact pathway work in nature-based solutions.

      The wide range of research topics underscores the Climate and Sustainability Program’s goal of bringing together diverse interests, backgrounds, and areas of study even within the same major. For example, Helena McDonald is studying pollution impacts of rocket launches, while Aviva Intveld is analyzing the paleoclimate and paleoenvironment background of the first peopling of the Americas. Both students are Earth, atmospheric and planetary sciences majors but are researching climate impacts from very different perspectives. Intveld was recently named a 2023 Gates Cambridge Scholar.

      “There are students represented from several majors in the program, and some people are working on more technical projects, while others are interpersonal. Both approaches are really necessary in the pursuit of climate resilience,” says Grace Harrington, who is majoring in civil and environmental engineering and whose project investigates ways to optimize the power of the wind farm. “I think it’s one of the few classes I’ve taken with such an interdisciplinary nature.”

      Shivani Konduru, electrical engineering and computer science major, during a classroom lecture

      Photo: Andrew Okyere

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      Perspectives and guidance from MIT and industry expertsAs students are developing these projects, they are also taking the program’s course (Climate.UAR), which covers key topics in climate change science, decarbonization strategies, policy, environmental justice, and quantitative methods for evaluating social and environmental impacts. The course is cross-listed in departments across all five schools and is taught by an experienced and interdisciplinary team. Desirée Plata was central to developing the Climate and Sustainability Scholars Programs and course with Associate Professor Elsa Olivetti, who taught the first semester. Olivetti is now co-teaching the second semester with Jeffrey C. Grossman, the Morton and Claire Goulder and Family Professor in Environmental Systems, head of the Department of Materials Science and Engineering, and MCSC co-director. The course’s writing instructors are Caroline Beimford and David Larson.  

      “I have been introduced to a lot of new angles in the climate space through the weekly guest lecturers, who each shared a different sustainability-related perspective,” says Claire Kim. “As a chemical engineering major, I have mostly looked into the technologies for decarbonization, and how to scale them, so learning about policy, for example, was helpful for me. Professor Black from the Department of History spoke about how we can analyze the effectiveness of past policy to guide future policy, while Professor Selin talked about framing different climate policies as having co-benefits. These perspectives are really useful because no matter how good a technology is, you need to convince other people to adopt it, or have strong policy in place to encourage its use, in order for it to be effective.”

      Bringing the industry perspective, guests have presented from MCSC member companies such as PepsiCo, Holcim, Apple, Cargill, and Boeing. As an example, in one class, climate leaders from three companies presented together on their approaches to setting climate goals, barriers to reaching them, and ways to work together. “When I presented to the class, alongside my counterparts at Apple and Boeing, the student questions pushed us to explain how can collaborate on ways to achieve our climate goals, reflecting the broader opportunity we find within the MCSC,” says Dana Boyer, sustainability manager at Cargill.

      Witnessing the cross-industry dynamics unfold in class was particularly engaging for the students. “The most beneficial part of the program for me is the number of guest lectures who have come in to the class, not only from MIT but also from the industry side,” Grace Harrington adds. “The diverse range of people talking about their own fields has allowed me to make connections between all my classes.”Bringing in perspectives from both academia and industry is a reflection of the MCSC’s larger mission of linking its corporate members with each other and with the MIT community to develop scalable climate solutions.“In addition to focusing on an independent research project and engaging with a peer community, we’ve had the opportunity to hear from speakers across the sustainability space who are also part of or closely connected to the MIT ecosystem,” says Anushree Chaudhuri. “These opportunities have helped me make connections and learn about initiatives at the Institute that are closely related to existing or planned student sustainability projects. These connections — across topics like waste management, survey best practices, and climate communications — have strengthened student projects and opened pathways for future collaborations.

      Basuhi Ravi, MIT PhD candidate, giving a guest lecture

      Photo: Andrew Okyere

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      Having a positive impact as students and after graduation

      At the start of the program, students identified several goals, including developing focused independent research questions, drawing connections and links with real-world challenges, strengthening their critical thinking skills, and reflecting on their future career ambitions. A common thread throughout them all: the commitment to having a meaningful impact on climate and sustainability challenges both as students now, and as working professionals after graduation.“I’ve absolutely loved connecting with like-minded peers through the program. I happened to know most of the students coming in from various other communities on campus, so it’s been a really special experience for all of these people who I couldn’t connect with as a cohesive cohort before to come together. Whenever we have small group discussions in class, I’m always grateful for the time to learn about the interdisciplinary research projects everyone is involved with,” concludes Chaudhuri. “I’m looking forward to staying in touch with this group going forward, since I think most of us are planning on grad school and/or careers related to climate and sustainability.”

      The MCSC Climate and Sustainability Scholars Program is representative of MIT’s ambitious and bold initiatives on climate and sustainability — bringing together faculty and students across MIT to collaborate with industry on developing climate and sustainability solutions in the context of undergraduate education and research. Learn about how you can get involved. More

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      Responding to Ukraine’s “ocean of suffering”

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      Within 72 hours of the first Russian missiles striking Kyiv, Ukraine, in February 2022, Ian Miller SM ’19 boarded a flight for Poland.

      Later, he’d say he felt motivated by Kyiv’s “tragic ocean of suffering” and Ukrainian President Zelensky’s pleas for help. But he arrived with little notion of what to do.

      As he’d anticipated, his hotel in Rzeszów turned out to be a hub for aid workers and journalists. Miller was on his laptop, using the lobby Wi-Fi to work remotely as an MIT Energy Initiative (MITEI) project manager, when he overheard a reporter interviewing a Finnish man about his efforts to get bulletproof vests and helmets to the front lines.

      Miller soon found himself loading supplies onto trains that had brought huge numbers of refugees — mostly women, children, and the elderly — to the station in Rzeszów. The trains ran back at night, their empty seats filled with medical supplies, generators, and baby food, their lights dimmed to reduce the chances of attack.

      In April 2022, Miller and volunteers from a half-dozen countries planned and drove a convoy of trucks packed with tourniquets, bandages, and bulletproof vests across the border, arriving at the site of the Bucha massacre soon after the Russians retreated.

      Miller peered into a mass grave. “They were still excavating it, and those weren’t soldiers, you know?” he says. “I try to avoid looking at things like that too often, because it doesn’t help us save lives to be horrified all the time.” He downplays any potential danger to himself, telling his family he’s safer where he is than in parts of the United States.

      Soon after his first trip across the border, Miller convinced his former MIT roommate, Evan Platt SM ’20, to come help. “Just for a week,” he told Platt.

      Inspired by energy

      Miller and Platt met in 2008 in Washington, where Platt was interning at the White House and Miller was about to start his senior year at Georgetown University.

      Miller majored in government, but his interest in energy policy and technology grew during the years after graduation he spent teaching science to primary and secondary school students in New York, where he’d grown up; in Boston; and in Kampala, Uganda. “Some of the most fun, inspiring, engaging lessons and modules I did with the kids were focused on energy,” he recalls.

      While pursuing an MIT master of science in chemical engineering from 2016 to 2018, he started researching photovoltaics and wind power. He held leadership positions with the MIT Energy Conference and the MIT Energy Club.

      After joining MITEI, Miller worked on electric vehicles (EVs), EV charging patterns, and other applications. He became project manager and research specialist for the Sustainable Energy System Analysis Modeling Environment (SESAME), which models the levels of greenhouse gas emissions from multiple energy sectors in future scenarios.

      Miller and Platt reconnected and shared an apartment for three years. Platt studied systems design and management through a joint MIT School of Engineering and Sloan School of Management program, then stayed on to work for the MIT Technology Licensing Office.

      Platt left MIT to pursue other interests in 2020. The next time the two would see each other would be in Poland.

      “It’s not easy living and working in an active combat zone,” Platt says. “There is nobody on Earth I would rather be navigating this environment with than Ian.”

      Navigating the last mile

      In Rzeszów and Ukraine, Miller and U.S. Air Force veteran Mark Lindquist oversaw fulfillment for the new team. With the help of Google Translate, their phones lit up with encrypted texts to and from Polish customs agents and Ukrainian warehouse operators.

      Platt and two Ukrainian team members took the lead on a needs analysis of what was most in demand at the front. Another team member led procurement. Their efforts crystallized in the creation of Zero Line, a tax-exempt nonprofit that works closely with the Ukrainian government at the front line (a.k.a. “the zero line”).

      With Platt on board, “we got more rigorous and quantitative in terms of lives-saved-per-dollar,” Miller says. A hundred dollars buys four tourniquets. A thousand dollars adds crude steel armor to a Jeep. Two thousand dollars provides a small observation drone or a satellite phone, equipment that locates Russian artillery and detects Russian attacks.

      “Russian artillery shells are the No. 1 killer of Ukrainians, causing around 80 percent of casualties,” he says. “Tourniquets save people injured by Russian shells, vehicles help evacuate them, and communications equipment prevents deadly injuries from occurring in the first place.”

      Miller’s skills in transportation and power system modeling, developed at MITEI under Principal Research Scientist Emre Gençer, helped the team transport more than 150 used vehicles — Nissan Pathfinders and vans for moving civilians away from the front, Ford pickups for transporting anti-missile defense systems — and hundreds of batteries, generators, drones, bulletproof vests, and helmets to the front through nightmarish logistical bottlenecks.

      Typically, supplies from the United States, Asia, and elsewhere in Europe move through Gdansk and Warsaw, then proceed via train or vehicle to warehouses in Lviv, around 70 kilometers east of the border. Next is the seven-hour trip to Kyiv or the 12-hour drive to Dnipro (the current southern edge of the safe “green zone”) and the final 200 kilometers to the front. Here, says Miller, drivers with training and protective gear, often members of the Ukrainian military, take vehicles and supplies to front-line end users.

      “From day one, we asked our Ukrainian members and partners for introductions, and we’re constantly looking for more,” Miller says. “When our vehicles reach the front lines, Evan’s team always does interviews about needs, and what’s working, what’s not. What’s saving the most lives.”

      “From my early days with Ian, it’s clear he was always looking for ways to help people. Connections were really important to him,” says MITEI Director Robert C. Armstrong. “When war broke out, he found the call to answer human need irresistible. I think many of us think of doing that, but we get bogged down in the mechanics of everyday life. He just picked up and went.

      “Ian is just a terrific person and a great role model,” Armstrong says.

      Accelerating peace

      From the time Miller arrived in late February through October 2022, he continued working remotely for MITEI. He now works full time as co-director of Zero Line. For the foreseeable future, Miller will remain in Ukraine and Poland.

      He wants to see Ukrainians “follow in the happy, free, prospering footsteps of other ex-Soviet states, like the Baltics,” he says. He’d like to see the supply-chain innovations he and Platt achieved applied to humanitarian crises elsewhere.

      To date, Zero Line has raised more than $5 million in donations and delivered hundreds of tons of high-impact aid. “A key part of our approach has always been to support Ukrainians who excel in saving lives,” Miller says. To that end, the group works with Ukrainian software programmers and military units to create digital maps and processes to replace paper maps and operations “reminiscent of World War II,” Platt says. “Modernizing the intelligence infrastructure to facilitate better military operations is an important part of how a smaller military can beat a larger, more powerful military.”

      The fact that energy underlies so many aspects of the war is never far from Miller’s mind. Russia cut off energy supplies to Europe, then targeted Ukraine’s energy infrastructure. On one hand, he understands that billions of people in developing countries such as India need and deserve affordable energy. On the other hand, he says, oil and gas purchases by those countries are directly funding Russia’s war machine.

      “Everyone wants cheap renewables and we’re getting there, but it’s taking time. Lowering the costs of renewables and energy storage and supporting nascent commercial fusion — that’s a very important focus of MITEI. In the long run, that’ll help us reach a more peaceful world, without a doubt.”

      Work at MITEI and at Zero Line, Miller says, “truly could accelerate peace.” More

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      Flow batteries for grid-scale energy storage

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      In the coming decades, renewable energy sources such as solar and wind will increasingly dominate the conventional power grid. Because those sources only generate electricity when it’s sunny or windy, ensuring a reliable grid — one that can deliver power 24/7 — requires some means of storing electricity when supplies are abundant and delivering it later when they’re not. And because there can be hours and even days with no wind, for example, some energy storage devices must be able to store a large amount of electricity for a long time.

      A promising technology for performing that task is the flow battery, an electrochemical device that can store hundreds of megawatt-hours of energy — enough to keep thousands of homes running for many hours on a single charge. Flow batteries have the potential for long lifetimes and low costs in part due to their unusual design. In the everyday batteries used in phones and electric vehicles, the materials that store the electric charge are solid coatings on the electrodes. “A flow battery takes those solid-state charge-storage materials, dissolves them in electrolyte solutions, and then pumps the solutions through the electrodes,” says Fikile Brushett, an associate professor of chemical engineering at MIT. That design offers many benefits and poses a few challenges.

      Flow batteries: Design and operation

      A flow battery contains two substances that undergo electrochemical reactions in which electrons are transferred from one to the other. When the battery is being charged, the transfer of electrons forces the two substances into a state that’s “less energetically favorable” as it stores extra energy. (Think of a ball being pushed up to the top of a hill.) When the battery is being discharged, the transfer of electrons shifts the substances into a more energetically favorable state as the stored energy is released. (The ball is set free and allowed to roll down the hill.)

      At the core of a flow battery are two large tanks that hold liquid electrolytes, one positive and the other negative. Each electrolyte contains dissolved “active species” — atoms or molecules that will electrochemically react to release or store electrons. During charging, one species is “oxidized” (releases electrons), and the other is “reduced” (gains electrons); during discharging, they swap roles. Pumps are used to circulate the two electrolytes through separate electrodes, each made of a porous material that provides abundant surfaces on which the active species can react. A thin membrane between the adjacent electrodes keeps the two electrolytes from coming into direct contact and possibly reacting, which would release heat and waste energy that could otherwise be used on the grid.

      When the battery is being discharged, active species on the negative side oxidize, releasing electrons that flow through an external circuit to the positive side, causing the species there to be reduced. The flow of those electrons through the external circuit can power the grid. In addition to the movement of the electrons, “supporting” ions — other charged species in the electrolyte — pass through the membrane to help complete the reaction and keep the system electrically neutral.

      Once all the species have reacted and the battery is fully discharged, the system can be recharged. In that process, electricity from wind turbines, solar farms, and other generating sources drives the reverse reactions. The active species on the positive side oxidize to release electrons back through the wires to the negative side, where they rejoin their original active species. The battery is now reset and ready to send out more electricity when it’s needed. Brushett adds, “The battery can be cycled in this way over and over again for years on end.”

      Benefits and challenges

      A major advantage of this system design is that where the energy is stored (the tanks) is separated from where the electrochemical reactions occur (the so-called reactor, which includes the porous electrodes and membrane). As a result, the capacity of the battery — how much energy it can store — and its power — the rate at which it can be charged and discharged — can be adjusted separately. “If I want to have more capacity, I can just make the tanks bigger,” explains Kara Rodby PhD ’22, a former member of Brushett’s lab and now a technical analyst at Volta Energy Technologies. “And if I want to increase its power, I can increase the size of the reactor.” That flexibility makes it possible to design a flow battery to suit a particular application and to modify it if needs change in the future.

      However, the electrolyte in a flow battery can degrade with time and use. While all batteries experience electrolyte degradation, flow batteries in particular suffer from a relatively faster form of degradation called “crossover.” The membrane is designed to allow small supporting ions to pass through and block the larger active species, but in reality, it isn’t perfectly selective. Some of the active species in one tank can sneak through (or “cross over”) and mix with the electrolyte in the other tank. The two active species may then chemically react, effectively discharging the battery. Even if they don’t, some of the active species is no longer in the first tank where it belongs, so the overall capacity of the battery is lower.

      Recovering capacity lost to crossover requires some sort of remediation — for example, replacing the electrolyte in one or both tanks or finding a way to reestablish the “oxidation states” of the active species in the two tanks. (Oxidation state is a number assigned to an atom or compound to tell if it has more or fewer electrons than it has when it’s in its neutral state.) Such remediation is more easily — and therefore more cost-effectively — executed in a flow battery because all the components are more easily accessed than they are in a conventional battery.

      The state of the art: Vanadium

      A critical factor in designing flow batteries is the selected chemistry. The two electrolytes can contain different chemicals, but today the most widely used setup has vanadium in different oxidation states on the two sides. That arrangement addresses the two major challenges with flow batteries.

      First, vanadium doesn’t degrade. “If you put 100 grams of vanadium into your battery and you come back in 100 years, you should be able to recover 100 grams of that vanadium — as long as the battery doesn’t have some sort of a physical leak,” says Brushett.

      And second, if some of the vanadium in one tank flows through the membrane to the other side, there is no permanent cross-contamination of the electrolytes, only a shift in the oxidation states, which is easily remediated by re-balancing the electrolyte volumes and restoring the oxidation state via a minor charge step. Most of today’s commercial systems include a pipe connecting the two vanadium tanks that automatically transfers a certain amount of electrolyte from one tank to the other when the two get out of balance.

      However, as the grid becomes increasingly dominated by renewables, more and more flow batteries will be needed to provide long-duration storage. Demand for vanadium will grow, and that will be a problem. “Vanadium is found around the world but in dilute amounts, and extracting it is difficult,” says Rodby. “So there are limited places — mostly in Russia, China, and South Africa — where it’s produced, and the supply chain isn’t reliable.” As a result, vanadium prices are both high and extremely volatile — an impediment to the broad deployment of the vanadium flow battery.

      Beyond vanadium

      The question then becomes: If not vanadium, then what? Researchers worldwide are trying to answer that question, and many are focusing on promising chemistries using materials that are more abundant and less expensive than vanadium. But it’s not that easy, notes Rodby. While other chemistries may offer lower initial capital costs, they may be more expensive to operate over time. They may require periodic servicing to rejuvenate one or both of their electrolytes. “You may even need to replace them, so you’re essentially incurring that initial (low) capital cost again and again,” says Rodby.

      Indeed, comparing the economics of different options is difficult because “there are so many dependent variables,” says Brushett. “A flow battery is an electrochemical system, which means that there are multiple components working together in order for the device to function. Because of that, if you are trying to improve a system — performance, cost, whatever — it’s very difficult because when you touch one thing, five other things change.”

      So how can we compare these new and emerging chemistries — in a meaningful way — with today’s vanadium systems? And how do we compare them with one another, so we know which ones are more promising and what the potential pitfalls are with each one? “Addressing those questions can help us decide where to focus our research and where to invest our research and development dollars now,” says Brushett.

      Techno-economic modeling as a guide

      A good way to understand and assess the economic viability of new and emerging energy technologies is using techno-economic modeling. With certain models, one can account for the capital cost of a defined system and — based on the system’s projected performance — the operating costs over time, generating a total cost discounted over the system’s lifetime. That result allows a potential purchaser to compare options on a “levelized cost of storage” basis.

      Using that approach, Rodby developed a framework for estimating the levelized cost for flow batteries. The framework includes a dynamic physical model of the battery that tracks its performance over time, including any changes in storage capacity. The calculated operating costs therefore cover all services required over decades of operation, including the remediation steps taken in response to species degradation and crossover.

      Analyzing all possible chemistries would be impossible, so the researchers focused on certain classes. First, they narrowed the options down to those in which the active species are dissolved in water. “Aqueous systems are furthest along and are most likely to be successful commercially,” says Rodby. Next, they limited their analyses to “asymmetric” chemistries; that is, setups that use different materials in the two tanks. (As Brushett explains, vanadium is unusual in that using the same “parent” material in both tanks is rarely feasible.) Finally, they divided the possibilities into two classes: species that have a finite lifetime and species that have an infinite lifetime; that is, ones that degrade over time and ones that don’t.

      Results from their analyses aren’t clear-cut; there isn’t a particular chemistry that leads the pack. But they do provide general guidelines for choosing and pursuing the different options.

      Finite-lifetime materials

      While vanadium is a single element, the finite-lifetime materials are typically organic molecules made up of multiple elements, among them carbon. One advantage of organic molecules is that they can be synthesized in a lab and at an industrial scale, and the structure can be altered to suit a specific function. For example, the molecule can be made more soluble, so more will be present in the electrolyte and the energy density of the system will be greater; or it can be made bigger so it won’t fit through the membrane and cross to the other side. Finally, organic molecules can be made from simple, abundant, low-cost elements, potentially even waste streams from other industries.

      Despite those attractive features, there are two concerns. First, organic molecules would probably need to be made in a chemical plant, and upgrading the low-cost precursors as needed may prove to be more expensive than desired. Second, these molecules are large chemical structures that aren’t always very stable, so they’re prone to degradation. “So along with crossover, you now have a new degradation mechanism that occurs over time,” says Rodby. “Moreover, you may figure out the degradation process and how to reverse it in one type of organic molecule, but the process may be totally different in the next molecule you work on, making the discovery and development of each new chemistry require significant effort.”

      Research is ongoing, but at present, Rodby and Brushett find it challenging to make the case for the finite-lifetime chemistries, mostly based on their capital costs. Citing studies that have estimated the manufacturing costs of these materials, Rodby believes that current options cannot be made at low enough costs to be economically viable. “They’re cheaper than vanadium, but not cheap enough,” says Rodby.

      The results send an important message to researchers designing new chemistries using organic molecules: Be sure to consider operating challenges early on. Rodby and Brushett note that it’s often not until way down the “innovation pipeline” that researchers start to address practical questions concerning the long-term operation of a promising-looking system. The MIT team recommends that understanding the potential decay mechanisms and how they might be cost-effectively reversed or remediated should be an upfront design criterion.

      Infinite-lifetime species

      The infinite-lifetime species include materials that — like vanadium — are not going to decay. The most likely candidates are other metals; for example, iron or manganese. “These are commodity-scale chemicals that will certainly be low cost,” says Rodby.

      Here, the researchers found that there’s a wider “design space” of feasible options that could compete with vanadium. But there are still challenges to be addressed. While these species don’t degrade, they may trigger side reactions when used in a battery. For example, many metals catalyze the formation of hydrogen, which reduces efficiency and adds another form of capacity loss. While there are ways to deal with the hydrogen-evolution problem, a sufficiently low-cost and effective solution for high rates of this side reaction is still needed.

      In addition, crossover is a still a problem requiring remediation steps. The researchers evaluated two methods of dealing with crossover in systems combining two types of infinite-lifetime species.

      The first is the “spectator strategy.” Here, both of the tanks contain both active species. Explains Brushett, “You have the same electrolyte mixture on both sides of the battery, but only one of the species is ever working and the other is a spectator.” As a result, crossover can be remediated in similar ways to those used in the vanadium flow battery. The drawback is that half of the active material in each tank is unavailable for storing charge, so it’s wasted. “You’ve essentially doubled your electrolyte cost on a per-unit energy basis,” says Rodby.

      The second method calls for making a membrane that is perfectly selective: It must let through only the supporting ion needed to maintain the electrical balance between the two sides. However, that approach increases cell resistance, hurting system efficiency. In addition, the membrane would need to be made of a special material — say, a ceramic composite — that would be extremely expensive based on current production methods and scales. Rodby notes that work on such membranes is under way, but the cost and performance metrics are “far off from where they’d need to be to make sense.”

      Time is of the essence

      The researchers stress the urgency of the climate change threat and the need to have grid-scale, long-duration storage systems at the ready. “There are many chemistries now being looked at,” says Rodby, “but we need to hone in on some solutions that will actually be able to compete with vanadium and can be deployed soon and operated over the long term.”

      The techno-economic framework is intended to help guide that process. It can calculate the levelized cost of storage for specific designs for comparison with vanadium systems and with one another. It can identify critical gaps in knowledge related to long-term operation or remediation, thereby identifying technology development or experimental investigations that should be prioritized. And it can help determine whether the trade-off between lower upfront costs and greater operating costs makes sense in these next-generation chemistries.

      The good news, notes Rodby, is that advances achieved in research on one type of flow battery chemistry can often be applied to others. “A lot of the principles learned with vanadium can be translated to other systems,” she says. She believes that the field has advanced not only in understanding but also in the ability to design experiments that address problems common to all flow batteries, thereby helping to prepare the technology for its important role of grid-scale storage in the future.

      This research was supported by the MIT Energy Initiative. Kara Rodby PhD ’22 was supported by an ExxonMobil-MIT Energy Fellowship in 2021-22.

      This article appears in the Winter 2023 issue of Energy Futures, the magazine of the MIT Energy Initiative. More

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      in Energy

      An interdisciplinary approach to fighting climate change through clean energy solutions

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      In early 2021, the U.S. government set an ambitious goal: to decarbonize its power grid, the system that generates and transmits electricity throughout the country, by 2035. It’s an important goal in the fight against climate change, and will require a switch from current, greenhouse-gas producing energy sources (such as coal and natural gas), to predominantly renewable ones (such as wind and solar).

      Getting the power grid to zero carbon will be a challenging undertaking, as Audun Botterud, a principal research scientist at the MIT Laboratory for Information and Decision Systems (LIDS) who has long been interested in the problem, knows well. It will require building lots of renewable energy generators and new infrastructure; designing better technology to capture, store, and carry electricity; creating the right regulatory and economic incentives; and more. Decarbonizing the grid also presents many computational challenges, which is where Botterud’s focus lies. Botterud has modeled different aspects of the grid — the mechanics of energy supply, demand, and storage, and electricity markets — where economic factors can have a huge effect on how quickly renewable solutions get adopted.

      On again, off again

      A major challenge of decarbonization is that the grid must be designed and operated to reliably meet demand. Using renewable energy sources complicates this, as wind and solar power depend on an infamously volatile system: the weather. A sunny day becomes gray and blustery, and wind turbines get a boost but solar farms go idle. This will make the grid’s energy supply variable and hard to predict. Additional resources, including batteries and backup power generators, will need to be incorporated to regulate supply. Extreme weather events, which are becoming more common with climate change, can further strain both supply and demand. Managing a renewables-driven grid will require algorithms that can minimize uncertainty in the face of constant, sometimes random fluctuations to make better predictions of supply and demand, guide how resources are added to the grid, and inform how those resources are committed and dispatched across the entire United States.

      “The problem of managing supply and demand in the grid has to happen every second throughout the year, and given how much we rely on electricity in society, we need to get this right,” Botterud says. “You cannot let the reliability drop as you increase the amount of renewables, especially because I think that will lead to resistance towards adopting renewables.”

      That is why Botterud feels fortunate to be working on the decarbonization problem at LIDS — even though a career here is not something he had originally planned. Botterud’s first experience with MIT came during his time as a graduate student in his home country of Norway, when he spent a year as a visiting student with what is now called the MIT Energy Initiative. He might never have returned, except that while at MIT, Botterud met his future wife, Bilge Yildiz. The pair both ended up working at the Argonne National Laboratory outside of Chicago, with Botterud focusing on challenges related to power systems and electricity markets. Then Yildiz got a faculty position at MIT, where she is a professor of nuclear and materials science and engineering. Botterud moved back to the Cambridge area with her and continued to work for Argonne remotely, but he also kept an eye on local opportunities. Eventually, a position at LIDS became available, and Botterud took it, while maintaining his connections to Argonne.

      “At first glance, it may not be an obvious fit,” Botterud says. “My work is very focused on a specific application, power system challenges, and LIDS tends to be more focused on fundamental methods to use across many different application areas. However, being at LIDS, my lab [the Energy Analytics Group] has access to the most recent advances in these fundamental methods, and we can apply them to power and energy problems. Other people at LIDS are working on energy too, so there is growing momentum to address these important problems.”

      Weather, space, and time

      Much of Botterud’s research involves optimization, using mathematical programming to compare alternatives and find the best solution. Common computational challenges include dealing with large geographical areas that contain regions with different weather, different types and quantities of renewable energy available, and different infrastructure and consumer needs — such as the entire United States. Another challenge is the need for granular time resolution, sometimes even down to the sub-second level, to account for changes in energy supply and demand.

      Often, Botterud’s group will use decomposition to solve such large problems piecemeal and then stitch together solutions. However, it’s also important to consider systems as a whole. For example, in a recent paper, Botterud’s lab looked at the effect of building new transmission lines as part of national decarbonization. They modeled solutions assuming coordination at the state, regional, or national level, and found that the more regions coordinate to build transmission infrastructure and distribute electricity, the less they will need to spend to reach zero carbon.

      In other projects, Botterud uses game theory approaches to study strategic interactions in electricity markets. For example, he has designed agent-based models to analyze electricity markets. These assume each actor will make strategic decisions in their own best interest and then simulate interactions between them. Interested parties can use the models to see what would happen under different conditions and market rules, which may lead companies to make different investment decisions, or governing bodies to issue different regulations and incentives. These choices can shape how quickly the grid gets decarbonized.

      Botterud is also collaborating with researchers in MIT’s chemical engineering department who are working on improving battery storage technologies. Batteries will help manage variable renewable energy supply by capturing surplus energy during periods of high generation to release during periods of insufficient generation. Botterud’s group models the sort of charge cycles that batteries are likely to experience in the power grid, so that chemical engineers in the lab can test their batteries’ abilities in more realistic scenarios. In turn, this also leads to a more realistic representation of batteries in power system optimization models.

      These are only some of the problems that Botterud works on. He enjoys the challenge of tackling a spectrum of different projects, collaborating with everyone from engineers to architects to economists. He also believes that such collaboration leads to better solutions. The problems created by climate change are myriad and complex, and solving them will require researchers to cooperate and explore.

      “In order to have a real impact on interdisciplinary problems like energy and climate,” Botterud says, “you need to get outside of your research sweet spot and broaden your approach.” More

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      in Environment

      Fieldwork class examines signs of climate change in Hawaii

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      When Joy Domingo-Kameenui spent two weeks in her native Hawaii as part of MIT class 1.091 (Traveling Research Environmental eXperiences), she was surprised to learn about the number of invasive and endangered species. “I knew about Hawaiian ecology from middle and high school but wasn’t fully aware to the extent of how invasive species and diseases have resulted in many of Hawaii’s endemic species becoming threatened,” says Domingo-Kameenui.  

      Domingo-Kameenui was part of a group of MIT students who conducted field research on the Big Island of Hawaii in the Traveling Research Environmental eXperiences (TREX) class offered by the Department of Civil and Environmental Engineering. The class provides undergraduates an opportunity to gain hands-on environmental fieldwork experience using Hawaii’s geology, chemistry, and biology to address two main topics of climate change concern: sulfur dioxide (SO2) emissions and forest health.

      “Hawaii is this great system for studying the effects of climate change,” says David Des Marais, the Cecil and Ida Green Career Development Professor of Civil and Environmental Engineering and lead instructor of TREX. “Historically, Hawaii has had occasional mild droughts that are related to El Niño, but the droughts are getting stronger and more frequent. And we know these types of extreme weather events are going to happen worldwide.”

      Climate change impacts on forests

      The frequency and intensity of extreme events are also becoming more of a problem for forests and plant life. Forests have a certain distribution of vegetation and as you get higher in elevation, the trees gradually turn into shrubs, and then rock. Trees don’t grow above the timberline, where the temperature and precipitation changes dramatically at the high elevations. “But unlike the Sierra Nevada or the Rockies, where the trees gradually change as you go up the mountains, in Hawaii, they gradually change, and then they just stop,” says Des Marais.

      “Why this is an interesting model for climate change,” explains Des Marais, “is that line where trees stop [growing] is going to move, and it’s going to become more unstable as the trade winds are affected by global patterns of air circulation, which are changing because of climate change.”

      The research question that Des Marais asks students to explore — How is the Hawaiian forest going to be affected by climate change? — uses Hawaii as a model for broader patterns in climate change for forests.

      To dive deeper into this question, students trekked up the mountain taking ground-level measurements of canopy cover with a camera app on their cellphones, estimating how much tree coverage blankets the sky when looking up, and observing how the canopy cover thins until they see no tree coverage at all as they go further up the mountain. Drones also flew above the forest to measure chlorophyll and how much plant matter remains. And then satellite data products from NASA and the European Space Agency were used to measure the distribution of chlorophyll, climate, and precipitation data from space.

      They also worked directly with community stakeholders at three locations around the island to access the forests and use technology to assess the ecology and biodiversity challenges. One of those stakeholders was the Kamehameha Schools Natural and Cultural Ecosystems Division, whose mission is to preserve the land and manage it in a sustainable way. Students worked with their plant biologists to help address and think about what management decisions will support the future health of their forests.

      “Across the island, rising temperatures and abnormal precipitation patterns are the main drivers of drought, which really has significant impacts on biodiversity, and overall human health,” says Ava Gillikin, a senior in civil and environmental engineering.

      Gillikin adds that “a good proportion of the island’s water system relies on rainwater catchment, exposing vulnerabilities to fluctuations in rain patterns that impact many people’s lives.”

      Deadly threats to native plants

      The other threats to Hawaii’s forests are invasive species causing ecological harm, from the prevalence of non-indigenous mosquitoes leading to increases in avian malaria and native bird death that threaten the native ecosystem, to a plant called strawberry guava.

      Strawberry guava is taking over Hawaii’s native ōhiʻa trees, which Domingo-Kameenui says is also contributing to Hawaii’s water production. “The plants absorb water quickly so there’s less water runoff for groundwater systems.”

      A fungal pathogen is also infecting native ōhiʻa trees. The disease, called rapid ʻohiʻa death (ROD), kills the tree within a few days to weeks. The pathogen was identified by researchers on the island in 2014 from the fungal genus, Ceratocystis. The fungal pathogen was likely carried into the forests by humans on their shoes, or contaminated tools, gear, and vehicles traveling from one location to another. The fungal disease is also transmitted by beetles that bore into trees and create a fine powder-like dust. This dust from an infected tree is then mixed with the fungal spores and can easily spread to other trees by wind, or contaminated soil.

      For Gillikin, seeing the effects of ROD in the field highlighted the impact improper care and preparation can have on native forests. “The ‘ohi’a tree is one of the most prominent native trees, and ROD can kill the trees very rapidly by putting a strain on its vascular system and preventing water from reaching all parts of the tree,” says Gillikin.

      Before entering the forests, students sprayed their shoes and gear with ethanol frequently to prevent the spread.

      Uncovering chemical and particle formation

      A second research project in TREX studied volcanic smog (vog) that plagues the air, making visibility problematic at times and causing a lot of health problems for people in Hawaii. The active Kilauea volcano releases SO2 into the atmosphere. When the SO2 mixes with other gasses emitted from the volcano and interacts with sunlight and the atmosphere, particulate matter forms.

      Students in the Kroll Group, led by Jesse Kroll, professor of civil and environmental engineering and chemical engineering, have been studying SO2 and particulate matter over the years, but not the chemistry directly in how those chemical transformations occur.

      “There’s a hypothesis that there is a functional connection between the SO2 and particular matter, but that’s never been directly demonstrated,” says Des Marais.

      Testing that hypothesis, the students were able to measure two different sizes of particulate matter formed from the SO2 and develop a model to show how much vog is generated downstream of the volcano.

      They spent five days at two sites from sunrise to late morning measuring particulate matter formation as the sun comes up and starts creating new particles. Using a combination of data sources for meteorology, such as UV index, wind speed, and humidity, the students built a model that demonstrates all the pieces of an equation that can calculate when new particles are formed.

      “You can build what you think that equation is based on first-principle understanding of the chemical composition, but what they did was measured it in real time with measurements of the chemical reagents,” says Des Marias.

      The students measured what was going to catalyze the chemical reaction of particulate matter — for instance, things like sunlight and ozone — and then calculated numbers to the outputs.

      “What they found, and what seems to be happening, is that the chemical reagents are accumulating overnight,” says Des Marais. “Then as soon as the sun rises in the morning all the transformation happens in the atmosphere. A lot of the reagents are used up and the wind blows everything away, leaving the other side of the island with polluted air,” adds Des Marais.

      “I found the vog particle formation fieldwork a surprising research learning,” adds Domingo-Kameenui who did some atmospheric chemistry research in the Kroll Group. “I just thought particle formation happened in the air, but we found wind direction and wind speed at a certain time of the day was extremely important to particle formation. It’s not just chemistry you need to look at, but meteorology and sunlight,” she adds.

      Both Domingo-Kameenui and Gillikin found the fieldwork class an important and memorable experience with new insight that they will carry with them beyond MIT.  

      How Gillikin approaches fieldwork or any type of community engagement in another culture is what she will remember most. “When entering another country or culture, you are getting the privilege to be on their land, to learn about their history and experiences, and to connect with so many brilliant people,” says Gillikin. “Everyone we met in Hawaii had so much passion for their work, and approaching those environments with respect and openness to learn is what I experienced firsthand and will take with me throughout my career.” More

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      in Energy

      Shrinky Dinks, nail polish, and smelly bacteria

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      In a lab on the fourth floor of MIT’s Building 56, a group of Massachusetts high school students gathered around a device that measures conductivity.

      Vincent Nguyen, 15, from Saugus, thought of the times the material on their sample electrode flaked off the moment they took it out of the oven. Or how the electrode would fold weirdly onto itself. The big fails were kind of funny, but discouraging. The students had worked for a month, experimenting with different materials, and 17-year-old Brianna Tong of Malden wondered if they’d finally gotten it right: Would their electrode work well enough to power a microbial fuel cell?

      The students secured their electrode with alligator clips, someone hit start, and the teens watched anxiously as the device searched for even the faintest electrical current.

      Capturing electrons from bacteria

      Last July, Tong, Nguyen, and six other students from Malden Catholic High School commuted between the lab of MIT chemical engineer Ariel L. Furst and their school’s chemistry lab. Their goal was to fashion electrodes for low-cost microbial fuel cells — miniature bioreactors that generate small amounts of electricity by capturing electrons transferred from living microbes. These devices can double as electrochemical sensors.

      Furst, the Paul M. Cook Career Development Professor of Chemical Engineering, uses a mix of electrochemistry, microbial engineering, and materials science to address challenges in human health and clean energy. “The goal of all of our projects is to increase sustainability, clean energy, and health equity globally,” she says.

      Electrochemical sensors are powerful, sensitive detection and measurement tools. Typically, their electrodes need to be built in precisely engineered environments. “Thinking about ways of making devices without needing a cleanroom is important for coming up with inexpensive devices that can be deployed in low-resource settings under non-ideal conditions,” Furst says.

      For 17-year-old Angelina Ang of Everett, the project illuminated the significance of “coming together to problem-solve for a healthier and more sustainable earth,” she says. “It made me realize that we hold the answers to fix our dying planet.”

      With the help of a children’s toy called Shrinky Dinks, carbon-based materials, nail polish, and a certain smelly bacterium, the students got — literally — a trial-by-fire introduction to the scientific method. At one point, one of their experimental electrodes burst into flames. Other results were more promising.

      The students took advantage of the electrical properties of a bacterium — Shewanella oneidensis — that’s been called nature’s microscopic power plant. As part of their metabolism, Shewanella oneidensis generate electricity by oxidizing organic matter. In essence, they spit out electrons. Put enough together, and you get a few milliamps.

      To build bacteria-friendly electrodes, one of the first things the students did was culture Shewanella. They learned how to pour a growth medium into petri dishes where the reddish, normally lake-living bacteria could multiply. The microbes, Furst notes, are a little stinky, like cabbage. “But we think they’re really cool,” she says.

      With the right engineering, Shewanella can produce electric current when they detect toxins in water or soil. They could be used for bioremediation of wastewater. Low-cost versions could be useful for areas with limited or no access to reliable electricity and clean water.

      Next-generation chemists

      The Malden Catholic-MIT program resulted from a fluke encounter between Furst and a Malden Catholic parent.

      Mary-Margaret O’Donnell-Zablocki, then a medicinal chemist at a Kendall Square biotech startup, met Furst through a mutual friend. She asked Furst if she’d consider hosting high school chemistry students in her lab for the summer.

      Furst was intrigued. She traces her own passion for science to a program she’d happened upon between her junior and senior years in high school in St. Louis. The daughter of a software engineer and a businesswoman, Furst was casting around for potential career interests when she came across a summer program that enlisted scientists in academia and private research to introduce high school students and teachers to aspects of the scientific enterprise.

      “That’s when I realized that research is not like a lab class where there’s an expected outcome,” Furst recalls. “It’s so much cooler than that.”

      Using startup funding from an MIT Energy Initiative seed grant, Furst developed a curriculum with Malden Catholic chemistry teacher Seamus McGuire, and students were invited to apply. In addition to Tong, Ang, and Nguyen, participants included Chengxiang Lou, 18, from China; Christian Ogata, 14, of Wakefield; Kenneth Ramirez, 17, of Everett; Isaac Toscano, 17, of Medford; and MaryKatherine Zablocki, 15, of Revere and Wakefield. O’Donnell-Zablocki was surprised — and pleased — when her daughter applied to the program and was accepted.

      Furst notes that women are still underrepresented in chemical engineering. She was particularly excited to mentor young women through the program.

      A conductive ink

      The students were charged with identifying materials that had high conductivity, low resistance, were a bit soluble, and — with the help of a compatible “glue” — were able to stick to a substrate.

      Furst showed the Malden Catholic crew Shrinky Dinks — a common polymer popularized in the 1970s as a craft material that, when heated in a toaster oven, shrinks to a third of its size and becomes thicker and more rigid. Electrodes based on Shrinky Dinks would cost pennies, making it an ideal, inexpensive material for microbial fuel cells that could monitor, for instance, soil health in low- and middle-income countries.

      “Right now, monitoring soil health is problematic,” Furst says. “You have to collect a sample and bring it back to the lab to analyze in expensive equipment. But if we have these little devices that cost a couple of bucks each, we can monitor soil health remotely.”

      After a crash course in conductive carbon-based inks and solvent glues, the students went off to Malden Catholic to figure out what materials they wanted to try.

      Tong rattled them off: carbon nanotubes, carbon nanofibers, graphite powder, activated carbon. Potential solvents to help glue the carbon to the Shrinky Dinks included nail polish, corn syrup, and embossing ink, to name a few. They tested and retested. When they hit a dead end, they revised their hypotheses.

      They tried using a 3D printed stencil to daub the ink-glue mixture onto the Shrinky Dinks. They hand-painted them. They tried printing stickers. They worked with little squeegees. They tried scooping and dragging the material. Some of their electro-materials either flaked off or wouldn’t stick in the heating process.

      “Embossing ink never dried after baking the Shrinky Dink,” Ogata recalls. “In fact, it’s probably still liquid! And corn syrup had a tendency to boil. Seeing activated carbon ignite or corn syrup boiling in the convection oven was quite the spectacle.”

      “After the electrode was out of the oven and cooled down, we would check the conductivity,” says Tong, who plans to pursue a career in science. “If we saw there was a high conductivity, we got excited and thought those materials worked.”

      The moment of truth came in Furst’s MIT lab, where the students had access to more sophisticated testing equipment. Would their electrodes conduct electricity?

      Many of them didn’t. Tong says, “At first, we were sad, but then Dr. Furst told us that this is what science is, testing repeatedly and sometimes not getting the results we wanted.” Lou agrees. “If we just copy the data left by other scholars and don’t collect and figure it out by ourselves, then it is difficult to be a qualified researcher,” he says.

      Some of the students plan to continue the project one afternoon a week at MIT and as an independent study at Malden Catholic. The long-term goal is to create a field-based soil sensor that employs a bacterium like Shewanella.

      By chance, the students’ very first electrode — made of graphite powder ink and nail polish glue — generated the most current. One of the team’s biggest surprises was how much better black nail polish worked than clear nail polish. It turns out black nail polish contains iron-based pigment — a conductor. The unexpected win took some of the sting out of the failures.

      “They learned a very hard lesson: Your results might be awesome, and things are exciting, but then nothing else might work. And that’s totally fine,” Furst says.

      This article appears in the Winter 2023 issue of Energy Futures, the magazine of the MIT Energy Initiative. More

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      in Environment

      Nanotube sensors are capable of detecting and distinguishing gibberellin plant hormones

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      Researchers from the Disruptive and Sustainable Technologies for Agricultural Precision (DiSTAP) interdisciplinary research group of the Singapore-MIT Alliance for Research and Technology (SMART), MIT’s research enterprise in Singapore, and their collaborators from Temasek Life Sciences Laboratory have developed the first-ever nanosensor that can detect and distinguish gibberellins (GAs), a class of hormones in plants that are important for growth. The novel nanosensors are nondestructive, unlike conventional collection methods, and have been successfully tested in living plants. Applied in the field for early-stage plant stress monitoring, the sensors could prove transformative for agriculture and plant biotechnology, giving farmers interested in high-tech precision agriculture and crop management a valuable tool to optimize yield.

      The researchers designed near-infrared fluorescent carbon nanotube sensors that are capable of detecting and distinguishing two plant hormones, GA3 and GA4. Belonging to a class of plant hormones known as gibberellins, GA3 and GA4 are diterpenoid phytohormones produced by plants that play an important role in modulating diverse processes involved in plant growth and development. GAs are thought to have played a role in the driving forces behind the “green revolution” of the 1960s, which was in turn credited with averting famine and saving the lives of many worldwide. The continued study of gibberellins could lead to further breakthroughs in agricultural science and have implications for food security.

      Climate change, global warming, and rising sea levels cause farming soil to get contaminated by saltwater, raising soil salinity. In turn, high soil salinity is known to negatively regulate GA biosynthesis and promote GA metabolism, resulting in the reduction of GA content in plants. The new nanosensors developed by the SMART researchers allow for the study of GA dynamics in living plants under salinity stress at a very early stage, potentially enabling farmers to make early interventions when eventually applied in the field. This forms the basis of early-stage stress detection.

      Currently, methods to detect GA3 and GA4 typically require mass spectroscopy-based analysis, a time-consuming and destructive process. In contrast, the new sensors developed by the researchers are highly selective for the respective GAs and offer real-time, in vivo monitoring of changes in GA levels across a broad range of plant species.

      Described in a paper titled “Near-Infrared Fluorescent Carbon Nanotube Sensors for the Plant Hormone Family Gibberellins” published in the journal Nano Letters, the research represents a breakthrough for early-stage plant stress detection and holds tremendous potential to advance plant biotechnology and agriculture. This paper builds on previous research by the team at SMART DiSTAP on single-walled carbon nanotube-based nanosensors using the corona phase molecular recognition (CoPhMoRe) platform.

      Based on the CoPhMoRe concept introduced by the lab of MIT Professor Professor Michael Strano, the novel sensors are able to detect GA kinetics in the roots of a variety of model and non-model plant species, including Arabidopsis, lettuce, and basil, as well as GA accumulation during lateral root emergence, highlighting the importance of GA in root system architecture. This was made possible by the researchers’ related development of a new coupled Raman/near infrared fluorimeter that enables self-referencing of nanosensor near infrared fluorescence with its Raman G-band, a new hardware innovation that removes the need for a separate reference nanosensor and greatly simplifies the instrumentation requirements by using a single optical channel to measure hormone concentration.

      Using the reversible GA nanosensors, the researchers detected increased endogenous GA levels in mutant plants producing greater amounts of GA20ox1, a key enzyme in GA biosynthesis, as well as decreased GA levels in plants under salinity stress. When exposed to salinity stress, researchers also found that lettuce growth was severely stunted — an indication that only became apparent after 10 days. In contrast, the GA nanosensors reported decreased GA levels after just six hours, demonstrating their efficacy as a much earlier indicator of salinity stress.

      “Our CoPhMoRe technique allows us to create nanoparticles that act like natural antibodies in that they can recognize and lock onto specific molecules. But they tend to be far more stable than alternatives. We have used this method to successfully create nanosensors for plant signals such as hydrogen peroxide and heavy-metal pollutants like arsenic in plants and soil,” says Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT who is co-corresponding author and DiSTAP co-lead principal investigator. “The method works to create sensors for organic molecules like synthetic auxin — an important plant hormone — as we have shown. This latest breakthrough now extends this success to a plant hormone family called gibberellins — an exceedingly difficult one to recognize.”

      Strano adds: “The resulting technology offers a rapid, real-time, and in vivo method to monitor changes in GA levels in virtually any plant, and can replace current sensing methods which are laborious, destructive, species-specific, and much less efficient.”

      Mervin Chun-Yi Ang, associate scientific director at DiSTAP and co-first author of the paper, says, “More than simply a breakthrough in plant stress detection, we have also demonstrated a hardware innovation in the form of a new coupled Raman/NIR fluorimeter that enabled self-referencing of SWNT sensor fluorescence with its Raman G-band, representing a major advance in the translation of our nanosensing tool sets to the field. In the near future, our sensors can be combined with low-cost electronics, portable optodes, or microneedle interfaces for industrial use, transforming how the industry screens for and mitigates plant stress in food crops and potentially improving growth and yield.”

      The new sensors could yet have a variety of industrial applications and use cases. Daisuke Urano, a Temasek Life Sciences Laboratory principal investigator, National University of Singapore (NUS) adjunct assistant professor, and co-corresponding author of the paper, explains, “GAs are known to regulate a wide range of plant development processes, from shoot, root, and flower development, to seed germination and plant stress responses. With the commercialization of GAs, these plant hormones are also sold to growers and farmers as plant growth regulators to promote plant growth and seed germination. Our novel GA nanosensors could be applied in the field for early-stage plant stress monitoring, and also be used by growers and farmers to track the uptake or metabolism of GA in their crops.”

      The design and development of the nanosensors, creation and validation of the coupled Raman/near infrared fluorimeter and related image/data processing algorithms, as well as statistical analysis of readouts from plant sensors for this study were performed by SMART and MIT. The Temasek Life Sciences Laboratory was responsible for the design, execution, and analysis of plant-related studies, including validation of nanosensors in living plants.

      This research was carried out by SMART and supported by the National Research Foundation of Singapore under its Campus for Research Excellence And Technological Enterprise (CREATE) program. The DiSTAP program, led by Strano and Singapore co-lead principal investigator Professor Chua Nam Hai, addresses deep problems in food production in Singapore and the world by developing a suite of impactful and novel analytical, genetic, and biomaterial technologies. The goal is to fundamentally change how plant biosynthetic pathways are discovered, monitored, engineered, and ultimately translated to meet the global demand for food and nutrients. Scientists from MIT, Temasek Life Sciences Laboratory, Nanyang Technological University (NTU) and NUS are collaboratively developing new tools for the continuous measurement of important plant metabolites and hormones for novel discovery, deeper understanding and control of plant biosynthetic pathways in ways not yet possible, especially in the context of green leafy vegetables; leveraging these new techniques to engineer plants with highly desirable properties for global food security, including high yield density production, and drought and pathogen resistance, and applying these technologies to improve urban farming.

      SMART was established by MIT and the National Research Foundation of Singapore in 2007. SMART serves as an intellectual and innovation hub for research interactions between MIT and Singapore, undertaking cutting-edge research projects in areas of interest to both Singapore and MIT. SMART currently comprises an Innovation Center and five interdisciplinary research groups: Antimicrobial Resistance, Critical Analytics for Manufacturing Personalized-Medicine, DiSTAP, Future Urban Mobility, and Low Energy Electronic Systems. More