School of Engineering

Subterms

    More stories

    • 113 Shares179 Views

      in Security

      Microbes could help reduce the need for chemical fertilizers

      by

      Production of chemical fertilizers accounts for about 1.5 percent of the world’s greenhouse gas emissions. MIT chemists hope to help reduce that carbon footprint by replacing some chemical fertilizer with a more sustainable source — bacteria.

      Bacteria that can convert nitrogen gas to ammonia could not only provide nutrients that plants need, but also help regenerate soil and protect plants from pests. However, these bacteria are sensitive to heat and humidity, so it’s difficult to scale up their manufacture and ship them to farms.

      To overcome that obstacle, MIT chemical engineers have devised a metal-organic coating that protects bacterial cells from damage without impeding their growth or function. In a new study, they found that these coated bacteria improved the germination rate of a variety of seeds, including vegetables such as corn and bok choy.

      This coating could make it much easier for farmers to deploy microbes as fertilizers, says Ariel Furst, the Paul M. Cook Career Development Assistant Professor of Chemical Engineering at MIT and the senior author of the study.

      “We can protect them from the drying process, which would allow us to distribute them much more easily and with less cost because they’re a dried powder instead of in liquid,” she says. “They can also withstand heat up to 132 degrees Fahrenheit, which means that you wouldn’t have to use cold storage for these microbes.”

      Benjamin Burke ’23 and postdoc Gang Fan are the lead authors of the open-access paper, which appears in the Journal of the American Chemical Society Au. MIT undergraduate Pris Wasuwanich and Evan Moore ’23 are also authors of the study.

      Protecting microbes

      Chemical fertilizers are manufactured using an energy-intensive process known as Haber-Bosch, which uses extremely high pressures to combine nitrogen from the air with hydrogen to make ammonia.

      In addition to the significant carbon footprint of this process, another drawback to chemical fertilizers is that long-term use eventually depletes the nutrients in the soil. To help restore soil, some farmers have turned to “regenerative agriculture,” which uses a variety of strategies, including crop rotation and composting, to keep soil healthy. Nitrogen-fixing bacteria, which convert nitrogen gas to ammonia, can aid in this approach.

      Some farmers have already begun deploying these “microbial fertilizers,” growing them in large onsite fermenters before applying them to the soil. However, this is cost-prohibitive for many farmers.

      Shipping these bacteria to rural areas is not currently a viable option, because they are susceptible to heat damage. The microbes are also too delicate to survive the freeze-drying process that would make them easier to transport.

      To protect the microbes from both heat and freeze-drying, Furst decided to apply a coating called a metal-phenol network (MPN), which she has previously developed to encapsulate microbes for other uses, such as protecting therapeutic bacteria delivered to the digestive tract.

      The coatings contain two components — a metal and an organic compound called a polyphenol — that can self-assemble into a protective shell. The metals used for the coatings, including iron, manganese, aluminum, and zinc, are considered safe as food additives. Polyphenols, which are often found in plants, include molecules such as tannins and other antioxidants. The FDA classifies many of these polyphenols as GRAS (generally regarded as safe).

      “We are using these natural food-grade compounds that are known to have benefits on their own, and then they form these little suits of armor that protect the microbes,” Furst says.

      For this study, the researchers created 12 different MPNs and used them to encapsulate Pseudomonas chlororaphis, a nitrogen-fixing bacterium that also protects plants against harmful fungi and other pests. They found that all of the coatings protected the bacteria from temperatures up to 50 degrees Celsius (122 degrees Fahrenheit), and also from relative humidity up to 48 percent. The coatings also kept the microbes alive during the freeze-drying process.

      A boost for seeds

      Using microbes coated with the most effective MPN — a combination of manganese and a polyphenol called epigallocatechin gallate (EGCG) — the researchers tested their ability to help seeds germinate in a lab dish. They heated the coated microbes to 50 C before placing them in the dish, and compared them to fresh uncoated microbes and freeze-dried uncoated microbes.

      The researchers found that the coated microbes improved the seeds’ germination rate by 150 percent, compared to seeds treated with fresh, uncoated microbes. This result was consistent across several different types of seeds, including dill, corn, radishes, and bok choy.

      Furst has started a company called Seia Bio to commercialize the coated bacteria for large-scale use in regenerative agriculture. She hopes that the low cost of the manufacturing process will help make microbial fertilizers accessible to small-scale farmers who don’t have the fermenters needed to grow such microbes.

      “When we think about developing technology, we need to intentionally design it to be inexpensive and accessible, and that’s what this technology is. It would help democratize regenerative agriculture,” she says.

      The research was funded by the Army Research Office, a National Institutes of Health New Innovator Award, a National Institute for Environmental Health Sciences Core Center Grant, the CIFAR Azrieli Global Scholars Program, the MIT J-WAFS Program, the MIT Climate and Sustainability Consortium, and the MIT Deshpande Center. More

    • 50 Shares149 Views

      in Energy

      The power of knowledge

      by

      In his early career at MIT, Josh Kuffour’s academic interests spanned mathematics, engineering, and physics. He decided to major in chemical engineering, figuring it would draw on all three areas. Then, he found himself increasingly interested in the mathematical components of his studies and added a second major, applied mathematics.

      Now, with a double major and energy studies minor, Kuffour is still seeking to learn even more. He has made it a goal to take classes from as many different departments as he can before he graduates. So far, he has taken classes from 17 different departments, ranging from Civil and Environmental Engineering to Earth, Atmospheric, and Planetary Sciences to Linguistics and Philosophy.

      “It’s taught me about valuing different ways of thinking,” he says about this wide-ranging approach to the course catalog. “It’s also taught me to value blending disciplines as a whole. Learning about how other people think about the same problems from different perspectives allows for better solutions to be developed.”

      After graduation, Kuffour plans to pursue a master’s degree at MIT, either in the Technology and Policy Program or in the Department of Chemical Engineering. He intends to make renewable energy, and its role in addressing societal inequalities, the focus of his career after graduating, and eventually plans to become a teacher.

      Serving the public

      Recognizing the power of knowledge, Kuffour says he enjoys helping to educate others “in any way I can.” He is involved with several extracurriculars in which he can be a mentor for both peers and high school students.

      Kuffour has volunteered with the Educational Studies Program since his first semester at MIT. This club runs Splash, “a weekend-long learning extravaganza,” as Kuffour puts it, in which MIT students teach over 400 free classes on a huge variety of topics for local high school students.

      For his peers, Kuffour also participates in the Gordon Engineering Leadership Program (GEL). Here, he teaches first-year GEL students leadership skills that engineers may require in their future careers. In doing this, Kuffour says he develops his own leadership skills as well. He is also working as a teaching assistant for multivariable calculus this semester.

      Kuffour has also served as an advisor for the Concourse learning community; as president of his fraternity, Beta Theta Pi; as a student representative on the HASS requirement subcommittee; and as a publicist for the Reason for God series, which invites the MIT community to discuss the intersections of religion with various facets of human life.

      Renewable energy

      Kuffour’s interest in energy issues has grown and evolved in recent years. He first learned about the ecological condition of the world in the eighth grade after watching the climate change documentary “Earth 2100” in school. Going into high school and college, Kuffour says he started reading books, taking classes, watching documentaries, participating in beach and city clean ups, to learn as much as possible about the environment and      global warming.

      During the summer of 2023, Kuffour worked as an energy and climate analysis intern for the consulting company Keylogic and has continued helping the company shift programming languages to Python for evaluating the economics of different methods of decarbonizing electricity sectors in the U.S. He has also assisted in analyzing trends in U.S. natural gas imports, exports, production, and consumption since the early 2000s.            

      In his time as an undergraduate, Kuffour’s interest in renewable energy has taken on a more justice-focused perspective. He’s learned over the course of his that due to historical inequalities in the U.S., pollution and other environmental problems have disproportionately impacted people of lower economic status and people of color. Since global warming will exacerbate these impacts, Kuffour seeks to address these growing inequalities through his work in energy data analysis.        

      Translating interests into activity

      Kuffour’s pursuit to expand his worldview never rests, even outside of the classroom. In his free time, he enjoys listening to podcasts or watching documentaries on any subject. When attempting to list all his favorite podcasts, he cuts himself off, saying, “This could go on for a while.”

      In 2022, Kuffour participated on a whim with a group of friends in an American Institute of Chemical Engineers competition, where he was tasked with creating a 1-by-1 foot cube that could filter water to specifications provided by the competition. He says it was fun to apply what he was learning at MIT to a project all the way in Arizona. 

      Kuffour enjoys discovering new things with friends as much as on his own. Three years ago, he started an intramural soccer team with friends from the Interphase EDGE program, which attracted many people he had never interacted with before. The team has been playing nearly every week since and Kuffour says the experience has been, “very enriching.”

      Kuffour hopes other students will also seek out knowledge and experiences from a wide range of sources during their undergraduate years. He offers: “Try as many things as possible even if you think you know what you want to do, and appreciate everything life has to offer.” More

    • 100 Shares129 Views

      in Energy

      Ayomikun Ayodeji ’22 named a 2024 Rhodes Scholar

      by

      Ayomikun “Ayo” Ayodeji ’22 from Lagos, Nigeria, has been selected as a Rhodes Scholar for West Africa. He will begin fully funded postgraduate studies at Oxford University in the U.K. next fall.

      Ayodeji was supported by Associate Dean Kim Benard and the Distinguished Fellowships team in Career Advising and Professional Development, and received additional mentorship from the Presidential Committee on Distinguished Fellowships.

      “Ayo has worked hard to develop his vision and to express it in ways that will capture the imagination of the broader world. It is a thrill to see him recognized this year as a Rhodes Scholar,” says Professor Nancy Kanwisher, who co-chairs the committee along with Professor Will Broadhead.

      Ayodeji graduated from MIT in 2022 with BS degrees in chemical engineering and management. He is currently an associate at Boston Consulting Group.

      He is passionate about championing reliable energy access across the African landscape and fostering culturally inclusive communities. As a Rhodes Scholar, he will pursue an MSc in energy systems and an MSc in global governance and diplomacy.

      During his time at MIT, Ayodeji’s curiosity for energy innovations was fueled by his research on perovskite solar cells under the MIT Energy Initiative. He then went on to intern at Pioneer Natural Resources where he explored the boundless applications of machine learning tools in completions. At BCG, Ayodeji supports both public and private sector clients on a variety of renewable energy topics including clean energy transition, decarbonization roadmaps, and workforce development.

      Ayodeji’s community-oriented mindset led him to team up with a group of friends and partner with the Northeast Children’s Trust (NECT), an organization that helps children affected by the Boko Haram insurgency in northeastern Nigeria. The project, sponsored by Davis Projects for Peace and MIT’s PKG Center, expanded NECT’s programs via an offline, portable classroom server.

      Ayodeji served as an undergraduate representative on the MIT Department of Chemical Engineering’s Diversity, Equity, and Inclusion Committee. He was also vice president of the MIT African Students’ Association and a coordinator for the annual MIT International Students Orientation. More

    • 75 Shares159 Views

      in Environment

      Forging climate connections across the Institute

      by

      Climate change is the ultimate cross-cutting issue: Not limited to any one discipline, it ranges across science, technology, policy, culture, human behavior, and well beyond. The response to it likewise requires an all-of-MIT effort.

      Now, to strengthen such an effort, a new grant program spearheaded by the Climate Nucleus, the faculty committee charged with the oversight and implementation of Fast Forward: MIT’s Climate Action Plan for the Decade, aims to build up MIT’s climate leadership capacity while also supporting innovative scholarship on diverse climate-related topics and forging new connections across the Institute.

      Called the Fast Forward Faculty Fund (F^4 for short), the program has named its first cohort of six faculty members after issuing its inaugural call for proposals in April 2023. The cohort will come together throughout the year for climate leadership development programming and networking. The program provides financial support for graduate students who will work with the faculty members on the projects — the students will also participate in leadership-building activities — as well as $50,000 in flexible, discretionary funding to be used to support related activities. 

      “Climate change is a crisis that truly touches every single person on the planet,” says Noelle Selin, co-chair of the nucleus and interim director of the Institute for Data, Systems, and Society. “It’s therefore essential that we build capacity for every member of the MIT community to make sense of the problem and help address it. Through the Fast Forward Faculty Fund, our aim is to have a cohort of climate ambassadors who can embed climate everywhere at the Institute.”

      F^4 supports both faculty who would like to begin doing climate-related work, as well as faculty members who are interested in deepening their work on climate. The program has the core goal of developing cohorts of F^4 faculty and graduate students who, in addition to conducting their own research, will become climate leaders at MIT, proactively looking for ways to forge new climate connections across schools, departments, and disciplines.

      One of the projects, “Climate Crisis and Real Estate: Science-based Mitigation and Adaptation Strategies,” led by Professor Siqi Zheng of the MIT Center for Real Estate in collaboration with colleagues from the MIT Sloan School of Management, focuses on the roughly 40 percent of carbon dioxide emissions that come from the buildings and real estate sector. Zheng notes that this sector has been slow to respond to climate change, but says that is starting to change, thanks in part to the rising awareness of climate risks and new local regulations aimed at reducing emissions from buildings.

      Using a data-driven approach, the project seeks to understand the efficient and equitable market incentives, technology solutions, and public policies that are most effective at transforming the real estate industry. Johnattan Ontiveros, a graduate student in the Technology and Policy Program, is working with Zheng on the project.

      “We were thrilled at the incredible response we received from the MIT faculty to our call for proposals, which speaks volumes about the depth and breadth of interest in climate at MIT,” says Anne White, nucleus co-chair and vice provost and associate vice president for research. “This program makes good on key commitments of the Fast Forward plan, supporting cutting-edge new work by faculty and graduate students while helping to deepen the bench of climate leaders at MIT.”

      During the 2023-24 academic year, the F^4 faculty and graduate student cohorts will come together to discuss their projects, explore opportunities for collaboration, participate in climate leadership development, and think proactively about how to deepen interdisciplinary connections among MIT community members interested in climate change.

      The six inaugural F^4 awardees are:

      Professor Tristan Brown, History Section: Humanistic Approaches to the Climate Crisis  

      With this project, Brown aims to create a new community of practice around narrative-centric approaches to environmental and climate issues. Part of a broader humanities initiative at MIT, it brings together a global working group of interdisciplinary scholars, including Serguei Saavedra (Department of Civil and Environmental Engineering) and Or Porath (Tel Aviv University; Religion), collectively focused on examining the historical and present links between sacred places and biodiversity for the purposes of helping governments and nongovernmental organizations formulate better sustainability goals. Boyd Ruamcharoen, a PhD student in the History, Anthropology, and Science, Technology, and Society (HASTS) program, will work with Brown on this project.

      Professor Kerri Cahoy, departments of Aeronautics and Astronautics and Earth, Atmospheric, and Planetary Sciences (AeroAstro): Onboard Autonomous AI-driven Satellite Sensor Fusion for Coastal Region Monitoring

      The motivation for this project is the need for much better data collection from satellites, where technology can be “20 years behind,” says Cahoy. As part of this project, Cahoy will pursue research in the area of autonomous artificial intelligence-enabled rapid sensor fusion (which combines data from different sensors, such as radar and cameras) onboard satellites to improve understanding of the impacts of climate change, specifically sea-level rise and hurricanes and flooding in coastal regions. Graduate students Madeline Anderson, a PhD student in electrical engineering and computer science (EECS), and Mary Dahl, a PhD student in AeroAstro, will work with Cahoy on this project.

      Professor Priya Donti, Department of Electrical Engineering and Computer Science: Robust Reinforcement Learning for High-Renewables Power Grids 

      With renewables like wind and solar making up a growing share of electricity generation on power grids, Donti’s project focuses on improving control methods for these distributed sources of electricity. The research will aim to create a realistic representation of the characteristics of power grid operations, and eventually inform scalable operational improvements in power systems. It will “give power systems operators faith that, OK, this conceptually is good, but it also actually works on this grid,” says Donti. PhD candidate Ana Rivera from EECS is the F^4 graduate student on the project.

      Professor Jason Jackson, Department of Urban Studies and Planning (DUSP): Political Economy of the Climate Crisis: Institutions, Power and Global Governance

      This project takes a political economy approach to the climate crisis, offering a distinct lens to examine, first, the political governance challenge of mobilizing climate action and designing new institutional mechanisms to address the global and intergenerational distributional aspects of climate change; second, the economic challenge of devising new institutional approaches to equitably finance climate action; and third, the cultural challenge — and opportunity — of empowering an adaptive socio-cultural ecology through traditional knowledge and local-level social networks to achieve environmental resilience. Graduate students Chen Chu and Mrinalini Penumaka, both PhD students in DUSP, are working with Jackson on the project.

      Professor Haruko Wainwright, departments of Nuclear Science and Engineering (NSE) and Civil and Environmental Engineering: Low-cost Environmental Monitoring Network Technologies in Rural Communities for Addressing Climate Justice 

      This project will establish a community-based climate and environmental monitoring network in addition to a data visualization and analysis infrastructure in rural marginalized communities to better understand and address climate justice issues. The project team plans to work with rural communities in Alaska to install low-cost air and water quality, weather, and soil sensors. Graduate students Kay Whiteaker, an MS candidate in NSE, and Amandeep Singh, and MS candidate in System Design and Management at Sloan, are working with Wainwright on the project, as is David McGee, professor in earth, atmospheric, and planetary sciences.

      Professor Siqi Zheng, MIT Center for Real Estate and DUSP: Climate Crisis and Real Estate: Science-based Mitigation and Adaptation Strategies 

      See the text above for the details on this project. More

    • 138 Shares149 Views

      in Energy

      MIT startup has big plans to pull carbon from the air

      by

      In order to avoid the worst effects of climate change, the United Nations has said we’ll need to not only reduce emissions but also remove carbon dioxide from the atmosphere. One method for achieving carbon removal is direct air capture and storage. Such technologies are still in their infancy, but many efforts are underway to scale them up quickly in hopes of heading off the most catastrophic effects of climate change.

      The startup Noya, founded by Josh Santos ’14, is working to accelerate direct-air carbon removal with a low-power, modular system that can be mass manufactured and deployed around the world. The company plans to power its system with renewable energy and build its facilities near injection wells to store carbon underground.

      Using third-party auditors to verify the amount of carbon dioxide captured and stored, Noya is selling carbon credits to help organizations reach net-zero emissions targets.

      “Think of our systems for direct air capture like solar panels for carbon negativity,” says Santos, who formerly played a role in Tesla’s much-publicized manufacturing scale-up for its Model 3 electric sedan. “We can stack these boxes in a LEGO-like fashion to achieve scale in the field.”

      The three-year old company is currently building its first commercial pilot facility, and says its first full-scale commercial facility will have the capacity to pull millions of tons of carbon from the air each year. Noya has already secured millions of dollars in presales to help build its first facilities from organizations including Shopify, Watershed, and a university endowment.

      Santos says the ambitious approach, which is driven by the urgent need to scale carbon removal solutions, was influenced by his time at MIT.

      “I need to thank all of my MIT professors,” Santos says. “I don’t think any of this would be possible without the way in which MIT opened up my horizons by showing me what’s possible when you work really hard.”

      Finding a purpose

      Growing up in the southeastern U.S., Santos says he first recognized climate change as an issue by experiencing the increasing intensity of hurricanes in his neighborhood. One year a hurricane forced his family to evacuate their town. When they returned, their church was gone.

      “The storm left a really big mark on me and how I thought about the world,” Santos says. “I realized how much climate change can impact people.”

      When Santos came to MIT as an undergraduate, he took coursework related to climate change and energy systems, eventually majoring in chemical engineering. He also learned about startups through courses he took at the MIT Sloan School of Management and by taking part in MIT’s Undergraduate Research Opportunities Program (UROP), which exposed him to researchers in the early stages of commercializing research from MIT labs.

      More than the coursework, though, Santos says MIT instilled in him a desire to make a positive impact on the world, in part through a four-day development workshop called LeaderShape that he took one January during the Institute’s Independent Activities Period (IAP).

      “LeaderShape teaches students how to lead with integrity, and the core lesson is that any privilege you have you should try to leverage to improve the lives of other people,” Santos says. “That really stuck with me. Going to MIT is a huge privilege, and it makes me feel like I have a responsibility to put that privilege to work to the betterment of society. It shaped a lot of how I view my career.”

      After graduation, Santos worked at Tesla, then at Harley Davidson, where he worked on electric powertrains. Eventually he decided electric vehicle technology couldn’t solve climate change on its own, so in the spring of 2020 he founded Noya with friend Daniel Cavaro.

      The initial idea for Noya was to attach carbon capture devices to cooling towers to keep equipment costs low. The founders pivoted in response to the passage of the Inflation Reduction Act in 2022 because their machines weren’t big enough to qualify for the new tax credits in the law, which required each system to capture at least 1,000 tons of CO2 per year.

      Noya’s new systems will combine thousands of its modular units to create massive facilities that can capture millions of tons of CO2 right next to existing injection wells.

      Each of Noya’s units is about the size of a solar panel at about 6 feet wide, 4.5 feet tall, and 1 foot thick. A fan blows air through tiny channels in each unit that contain Noya’s carbon capture material. The company’s material solution consists of an activated carbon monolith and a proprietary chemical feedstock that binds to the carbon in the air. When the material becomes saturated with carbon, electricity is applied to the material and a light vacuum collects a pure stream of carbon.

      The goal is for each of Noya’s modules to remove about 60 tons of CO2 from the atmosphere per year.

      “Other direct air capture companies need a big hot piece of equipment — like an oven, steam generator, or kiln — that takes electricity and converts it to get heat to the material,” Santos says. “Any lost heat into the surrounding environment is excess cost. We skip the need for the excess equipment and their inefficiencies by adding the electricity directly to the material itself.”

      Scaling with urgency

      From its office in Oakland, California, Noya is putting an experimental module through tests to optimize its design. Noya will launch its first testing facility, which should remove about 350 tons of CO2 per year, in 2024. It has already secured renewable energy and injection storage partners for that facility. Over the next few years Noya plans to capture and remove thousands of tons of CO2, and the company’s first commercial-scale facility will aim to remove about 3 million tons of carbon annually.

      “That design is what we’ll replicate across the world to grow our planetary impact,” Santos says. “We’re trying to scale up as fast as possible.”

      Noya has already sold all of the carbon credits it expects to generate in its first five years, and the founders believe the growing demand from companies and governments to purchase high-quality carbon credits will outstrip supply for at least the next 10 years in the nascent carbon removal industry, which also includes approaches like enhanced rock weathering, biomass carbon storage, and ocean alkalinity enhancement.

      “We’re going to need something like 30 companies the size of Shell to achieve the scale we need,” Santos says. “I think there will be large companies in each of those verticals. We’re in the early innings here.”

      Santos believes the carbon removal market can scale without government mandates, but he also sees increasing government and public support for carbon removal technologies around the world.

      “Carbon removal is a waste management problem,” Santos says. “You can’t just throw trash in the middle of the street. The way we currently deal with trash is polluters pay to clean up their waste. Carbon removal should be like that. CO2 is a waste product, and we should have regulations in place that are requiring polluters, like businesses, to clean up their waste emissions. It’s a public good to provide cleaner air.” More

    • 138 Shares199 Views

      in Environment

      In a surprising finding, light can make water evaporate without heat

      by

      Evaporation is happening all around us all the time, from the sweat cooling our bodies to the dew burning off in the morning sun. But science’s understanding of this ubiquitous process may have been missing a piece all this time.

      In recent years, some researchers have been puzzled upon finding that water in their experiments, which was held in a sponge-like material known as a hydrogel, was evaporating at a higher rate than could be explained by the amount of heat, or thermal energy, that the water was receiving. And the excess has been significant — a doubling, or even a tripling or more, of the theoretical maximum rate.

      After carrying out a series of new experiments and simulations, and reexamining some of the results from various groups that claimed to have exceeded the thermal limit, a team of researchers at MIT has reached a startling conclusion: Under certain conditions, at the interface where water meets air, light can directly bring about evaporation without the need for heat, and it actually does so even more efficiently than heat. In these experiments, the water was held in a hydrogel material, but the researchers suggest that the phenomenon may occur under other conditions as well.

      The findings are published this week in a paper in PNAS, by MIT postdoc Yaodong Tu, professor of mechanical engineering Gang Chen, and four others.

      The phenomenon might play a role in the formation and evolution of fog and clouds, and thus would be important to incorporate into climate models to improve their accuracy, the researchers say. And it might play an important part in many industrial processes such as solar-powered desalination of water, perhaps enabling alternatives to the step of converting sunlight to heat first.

      The new findings come as a surprise because water itself does not absorb light to any significant degree. That’s why you can see clearly through many feet of clean water to the surface below. So, when the team initially began exploring the process of solar evaporation for desalination, they first put particles of a black, light-absorbing material in a container of water to help convert the sunlight to heat.

      Then, the team came across the work of another group that had achieved an evaporation rate double the thermal limit — which is the highest possible amount of evaporation that can take place for a given input of heat, based on basic physical principles such as the conservation of energy. It was in these experiments that the water was bound up in a hydrogel. Although they were initially skeptical, Chen and Tu starting their own experiments with hydrogels, including a piece of the material from the other group. “We tested it under our solar simulator, and it worked,” confirming the unusually high evaporation rate, Chen says. “So, we believed them now.” Chen and Tu then began making and testing their own hydrogels.

      They began to suspect that the excess evaporation was being caused by the light itself —that photons of light were actually knocking bundles of water molecules loose from the water’s surface. This effect would only take place right at the boundary layer between water and air, at the surface of the hydrogel material — and perhaps also on the sea surface or the surfaces of droplets in clouds or fog.

      In the lab, they monitored the surface of a hydrogel, a JELL-O-like matrix consisting mostly of water bound by a sponge-like lattice of thin membranes. They measured its responses to simulated sunlight with precisely controlled wavelengths.

      The researchers subjected the water surface to different colors of light in sequence and measured the evaporation rate. They did this by placing a container of water-laden hydrogel on a scale and directly measuring the amount of mass lost to evaporation, as well as monitoring the temperature above the hydrogel surface. The lights were shielded to prevent them from introducing extra heat. The researchers found that the effect varied with color and peaked at a particular wavelength of green light. Such a color dependence has no relation to heat, and so supports the idea that it is the light itself that is causing at least some of the evaporation.

      The puffs of white condensation on glass is water being evaporated from a hydrogel using green light, without heat.Image: Courtesy of the researchers

      The researchers tried to duplicate the observed evaporation rate with the same setup but using electricity to heat the material, and no light. Even though the thermal input was the same as in the other test, the amount of water that evaporated never exceeded the thermal limit. However, it did so when the simulated sunlight was on, confirming that light was the cause of the extra evaporation.

      Though water itself does not absorb much light, and neither does the hydrogel material itself, when the two combine they become strong absorbers, Chen says. That allows the material to harness the energy of the solar photons efficiently and exceed the thermal limit, without the need for any dark dyes for absorption.

      Having discovered this effect, which they have dubbed the photomolecular effect, the researchers are now working on how to apply it to real-world needs. They have a grant from the Abdul Latif Jameel Water and Food Systems Lab to study the use of this phenomenon to improve the efficiency of solar-powered desalination systems, and a Bose Grant to explore the phenomenon’s effects on climate change modeling.

      Tu explains that in standard desalination processes, “it normally has two steps: First we evaporate the water into vapor, and then we need to condense the vapor to liquify it into fresh water.” With this discovery, he says, potentially “we can achieve high efficiency on the evaporation side.” The process also could turn out to have applications in processes that require drying a material.

      Chen says that in principle, he thinks it may be possible to increase the limit of water produced by solar desalination, which is currently 1.5 kilograms per square meter, by as much as three- or fourfold using this light-based approach. “This could potentially really lead to cheap desalination,” he says.

      Tu adds that this phenomenon could potentially also be leveraged in evaporative cooling processes, using the phase change to provide a highly efficient solar cooling system.

      Meanwhile, the researchers are also working closely with other groups who are attempting to replicate the findings, hoping to overcome skepticism that has faced the unexpected findings and the hypothesis being advanced to explain them.

      The research team also included Jiawei Zhou, Shaoting Lin, Mohammed Alshrah, and Xuanhe Zhao, all in MIT’s Department of Mechanical Engineering. More

    • 138 Shares169 Views

      in Energy

      Engineers develop an efficient process to make fuel from carbon dioxide

      by

      The search is on worldwide to find ways to extract carbon dioxide from the air or from power plant exhaust and then make it into something useful. One of the more promising ideas is to make it into a stable fuel that can replace fossil fuels in some applications. But most such conversion processes have had problems with low carbon efficiency, or they produce fuels that can be hard to handle, toxic, or flammable.

      Now, researchers at MIT and Harvard University have developed an efficient process that can convert carbon dioxide into formate, a liquid or solid material that can be used like hydrogen or methanol to power a fuel cell and generate electricity. Potassium or sodium formate, already produced at industrial scales and commonly used as a de-icer for roads and sidewalks, is nontoxic, nonflammable, easy to store and transport, and can remain stable in ordinary steel tanks to be used months, or even years, after its production.

      The new process, developed by MIT doctoral students Zhen Zhang, Zhichu Ren, and Alexander H. Quinn; Harvard University doctoral student Dawei Xi; and MIT Professor Ju Li, is described this week in an open-access paper in Cell Reports Physical Science. The whole process — including capture and electrochemical conversion of the gas to a solid formate powder, which is then used in a fuel cell to produce electricity — was demonstrated at a small, laboratory scale. However, the researchers expect it to be scalable so that it could provide emissions-free heat and power to individual homes and even be used in industrial or grid-scale applications.

      Other approaches to converting carbon dioxide into fuel, Li explains, usually involve a two-stage process: First the gas is chemically captured and turned into a solid form as calcium carbonate, then later that material is heated to drive off the carbon dioxide and convert it to a fuel feedstock such as carbon monoxide. That second step has very low efficiency, typically converting less than 20 percent of the gaseous carbon dioxide into the desired product, Li says.

      By contrast, the new process achieves a conversion of well over 90 percent and eliminates the need for the inefficient heating step by first converting the carbon dioxide into an intermediate form, liquid metal bicarbonate. That liquid is then electrochemically converted into liquid potassium or sodium formate in an electrolyzer that uses low-carbon electricity, e.g. nuclear, wind, or solar power. The highly concentrated liquid potassium or sodium formate solution produced can then be dried, for example by solar evaporation, to produce a solid powder that is highly stable and can be stored in ordinary steel tanks for up to years or even decades, Li says.

      Several steps of optimization developed by the team made all the difference in changing an inefficient chemical-conversion process into a practical solution, says Li, who holds joint appointments in the departments of Nuclear Science and Engineering and of Materials Science and Engineering.

      The process of carbon capture and conversion involves first an alkaline solution-based capture that concentrates carbon dioxide, either from concentrated streams such as from power plant emissions or from very low-concentration sources, even open air, into the form of a liquid metal-bicarbonate solution. Then, through the use of a cation-exchange membrane electrolyzer, this bicarbonate is electrochemically converted into solid formate crystals with a carbon efficiency of greater than 96 percent, as confirmed in the team’s lab-scale experiments.

      These crystals have an indefinite shelf life, remaining so stable that they could be stored for years, or even decades, with little or no loss. By comparison, even the best available practical hydrogen storage tanks allow the gas to leak out at a rate of about 1 percent per day, precluding any uses that would require year-long storage, Li says. Methanol, another widely explored alternative for converting carbon dioxide into a fuel usable in fuel cells, is a toxic substance that cannot easily be adapted to use in situations where leakage could pose a health hazard. Formate, on the other hand, is widely used and considered benign, according to national safety standards.

      Several improvements account for the greatly improved efficiency of this process. First, a careful design of the membrane materials and their configuration overcomes a problem that previous attempts at such a system have encountered, where a buildup of certain chemical byproducts changes the pH, causing the system to steadily lose efficiency over time. “Traditionally, it is difficult to achieve long-term, stable, continuous conversion of the feedstocks,” Zhang says. “The key to our system is to achieve a pH balance for steady-state conversion.”

      To achieve that, the researchers carried out thermodynamic modeling to design the new process so that it is chemically balanced and the pH remains at a steady state with no shift in acidity over time. It can therefore continue operating efficiently over long periods. In their tests, the system ran for over 200 hours with no significant decrease in output. The whole process can be done at ambient temperatures and relatively low pressures (about five times atmospheric pressure).

      Another issue was that unwanted side reactions produced other chemical products that were not useful, but the team figured out a way to prevent these side reactions by the introduction of an extra “buffer” layer of bicarbonate-enriched fiberglass wool that blocked these reactions.

      The team also built a fuel cell specifically optimized for the use of this formate fuel to produce electricity. The stored formate particles are simply dissolved in water and pumped into the fuel cell as needed. Although the solid fuel is much heavier than pure hydrogen, when the weight and volume of the high-pressure gas tanks needed to store hydrogen is considered, the end result is an electricity output near parity for a given storage volume, Li says.

      The formate fuel can potentially be adapted for anything from home-sized units to large scale industrial uses or grid-scale storage systems, the researchers say. Initial household applications might involve an electrolyzer unit about the size of a refrigerator to capture and convert the carbon dioxide into formate, which could be stored in an underground or rooftop tank. Then, when needed, the powdered solid would be mixed with water and fed into a fuel cell to provide power and heat. “This is for community or household demonstrations,” Zhang says, “but we believe that also in the future it may be good for factories or the grid.”

      “The formate economy is an intriguing concept because metal formate salts are very benign and stable, and a compelling energy carrier,” says Ted Sargent, a professor of chemistry and of electrical and computer engineering at Northwestern University, who was not associated with this work. “The authors have demonstrated enhanced efficiency in liquid-to-liquid conversion from bicarbonate feedstock to formate, and have demonstrated these fuels can be used later to produce electricity,” he says.

      The work was supported by the U.S. Department of Energy Office of Science. More

    • 175 Shares179 Views

      in Energy

      Rafael Mariano Grossi speaks about nuclear power’s role at a critical moment in history

      by

      On Sept. 22, Rafael Mariano Grossi, director general of the International Atomic Energy Agency (IAEA), delivered the 2023 David J. Rose Lecture in Nuclear Technology at MIT. This lecture series was started nearly 40 years ago in honor of the late Professor David Rose — a nuclear engineering professor and fusion technology pioneer. In addition to his scientific contributions, Rose was invested in the ethical issues associated with new technologies. His widow, Renate Rose, who spoke briefly before Grossi’s lecture, said that her husband adamantly called for the abolishment of nuclear weapons, insisting that all science should serve the common good and that every scientist should follow his or her conscience.

      In his prefatory remarks, MIT Vice Provost Richard Lester, a former PhD student of David Rose, said that even today, he still feels the influence of his thesis advisor, many decades after they’d worked together. Lester called it a “great honor” to introduce Grossi, noting that the director general was guiding the agency through an especially demanding time. “His presence with us is a reminder that the biggest challenges we face today are truly global challenges, and that international organizations like the IAEA have a central role to play in resolving them.”

      The title of Grossi’s talk was “The IAEA at the Crossroads of History,” and he made a strong case for this being a critical juncture, or “inflection point,” for nuclear power. He started his speech, however, with somewhat of an historical footnote, discussing a letter that Rose sent in 1977 to Sigvard Eklund, IAEA’s then-director general. Rose urged the IAEA to establish a coordinated worldwide program in controlled fusion research. It took a while for the idea to gain traction, but international collaboration in fusion formally began in 1985, eight years after Rose’s proposal. “I thought I would begin with this story, because it shows that cooperation between MIT and the IAEA goes back a long way,” Grossi said.

      2023 David J. Rose Lecture in Nuclear TechnologyVideo: MIT Department of Nuclear Science and Engineering

      Overall, he painted a mostly encouraging picture for the future of nuclear power, largely based on its potential to generate electricity or thermal energy without adding greenhouse gases to the atmosphere. In the face of rapidly-unfolding climate change, Grossi said, “low-carbon nuclear power is now seen as part of [the] solution by an increasing number of people. It’s getting harder to be an environmentalist in good faith who is against nuclear.”

      Public acceptance is growing throughout the world, he added. In Sweden, where people had long protested against radioactive waste transport, a poll now shows that more than 85 percent of the people approve of the nation’s high-level waste handling and disposal facilities. Even Finland’s Green Party has embraced nuclear power, Grossi said. “I don’t think we could imagine a pro-nuclear Green Party five years ago, let alone in 1970 or ’80.”

      Fifty-seven nuclear reactors are being constructed right now in 17 countries. One of the world’s newest facilities, the Barakah nuclear power plant in the United Arab Emirates, “was built on ground rich in oil and natural gas,” he said. In China, the world’s first pebble-bed high-temperature reactor has been operating for two years, offering potential advantages in safety, efficiency, and modularity. For countries that don’t have any nuclear plants, small modular reactors of this kind “offer the chance of a more gradual and affordable way to scale up nuclear power,” Grossi noted. The IAEA is working with countries like Ghana, Kenya, and Senegal to help them develop the safety and regulatory infrastructures that would be needed to build and responsibly operate modular nuclear reactors like this.

      Grossi also discussed a number of lesser-known projects the IAEA is engaged in that have little to do with power generation. Seventy percent of the people in Africa, for example, have no access to radiotherapy to fight cancer. To this end, the IAEA is now helping to provide radiotherapy services in Tanzania and other African countries. At the IAEA’s Marine Environmental Laboratories in Monaco, researchers are using isotopic tracing techniques to study the impact of microplastic pollution on the oceans. The Covid-19 pandemic illustrated the potentially devastating effects of zoonotic diseases that can infect humans with animal-borne viruses. To counteract this threat, the IAEA has sent hundreds of reverse transcription-polymerase chain reaction (RT-PCR) machines — capable of detecting specific genetic materials in pathogens — to more than 130 countries.

      Meanwhile, new risks have emerged from the war in Ukraine, where fighting has raged for a year-and-a-half near the six nuclear reactors in Zaporizhzhia — Europe’s largest nuclear power plant. Early in the conflict, the IAEA sent a team of experts to monitor the plant and to do everything possible to prevent a nuclear accident that would bring “even more misery to people who are already suffering so much,” Grossi said. A major accident, he added, would likely stall investments in nuclear power at a time when its future prospects were starting to brighten.

      At the end of his talk, Grossi returned to the subject of fusion, which he expects to become an important energy source, perhaps in the not-too-distant future. He was encouraged by the visit he’d just had to the MIT spinoff company, Commonwealth Fusion Systems. With regard to fusion, he said, “for the first time, all the pieces of the puzzle are there: the physics, the policy drivers, and the investment.” In fact, an agreement was signed on the day of his lecture, which made MIT’s Plasma Science and Fusion Center an IAEA collaboration center — the second such center in the United States.

      “When I think of all the new forms of collaboration happening today, I imagine Professor Rose would be delighted,” Grossi said. “It really is something to hold [his] letter and know how much progress has been made since 1977 in fusion. I look forward to our collaboration going forward.” More