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      in Energy

      MIT startup has big plans to pull carbon from the air

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      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

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      in Energy

      Pixel-by-pixel analysis yields insights into lithium-ion batteries

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      By mining data from X-ray images, researchers at MIT, Stanford University, SLAC National Accelerator, and the Toyota Research Institute have made significant new discoveries about the reactivity of lithium iron phosphate, a material used in batteries for electric cars and in other rechargeable batteries.

      The new technique has revealed several phenomena that were previously impossible to see, including variations in the rate of lithium intercalation reactions in different regions of a lithium iron phosphate nanoparticle.

      The paper’s most significant practical finding — that these variations in reaction rate are correlated with differences in the thickness of the carbon coating on the surface of the particles — could lead to improvements in the efficiency of charging and discharging such batteries.

      “What we learned from this study is that it’s the interfaces that really control the dynamics of the battery, especially in today’s modern batteries made from nanoparticles of the active material. That means that our focus should really be on engineering that interface,” says Martin Bazant, the E.G. Roos Professor of Chemical Engineering and a professor of mathematics at MIT, who is the senior author of the study.

      This approach to discovering the physics behind complex patterns in images could also be used to gain insights into many other materials, not only other types of batteries but also biological systems, such as dividing cells in a developing embryo.

      “What I find most exciting about this work is the ability to take images of a system that’s undergoing the formation of some pattern, and learning the principles that govern that,” Bazant says.

      Hongbo Zhao PhD ’21, a former MIT graduate student who is now a postdoc at Princeton University, is the lead author of the new study, which appears today in Nature. Other authors include Richard Bratz, the Edwin R. Gilliland Professor of Chemical Engineering at MIT; William Chueh, an associate professor of materials science and engineering at Stanford and director of the SLAC-Stanford Battery Center; and Brian Storey, senior director of Energy and Materials at the Toyota Research Institute.

      “Until now, we could make these beautiful X-ray movies of battery nanoparticles at work, but it was challenging to measure and understand subtle details of how they function because the movies were so information-rich,” Chueh says. “By applying image learning to these nanoscale movies, we can extract insights that were not previously possible.”

      Modeling reaction rates

      Lithium iron phosphate battery electrodes are made of many tiny particles of lithium iron phosphate, surrounded by an electrolyte solution. A typical particle is about 1 micron in diameter and about 100 nanometers thick. When the battery discharges, lithium ions flow from the electrolyte solution into the material by an electrochemical reaction known as ion intercalation. When the battery charges, the intercalation reaction is reversed, and ions flow in the opposite direction.

      “Lithium iron phosphate (LFP) is an important battery material due to low cost, a good safety record, and its use of abundant elements,” Storey says. “We are seeing an increased use of LFP in the EV market, so the timing of this study could not be better.”

      Before the current study, Bazant had done a great deal of theoretical modeling of patterns formed by lithium-ion intercalation. Lithium iron phosphate prefers to exist in one of two stable phases: either full of lithium ions or empty. Since 2005, Bazant has been working on mathematical models of this phenomenon, known as phase separation, which generates distinctive patterns of lithium-ion flow driven by intercalation reactions. In 2015, while on sabbatical at Stanford, he began working with Chueh to try to interpret images of lithium iron phosphate particles from scanning tunneling X-ray microscopy.

      Using this type of microscopy, the researchers can obtain images that reveal the concentration of lithium ions, pixel-by-pixel, at every point in the particle. They can scan the particles several times as the particles charge or discharge, allowing them to create movies of how lithium ions flow in and out of the particles.

      In 2017, Bazant and his colleagues at SLAC received funding from the Toyota Research Institute to pursue further studies using this approach, along with other battery-related research projects.

      By analyzing X-ray images of 63 lithium iron phosphate particles as they charged and discharged, the researchers found that the movement of lithium ions within the material could be nearly identical to the computer simulations that Bazant had created earlier. Using all 180,000 pixels as measurements, the researchers trained the computational model to produce equations that accurately describe the nonequilibrium thermodynamics and reaction kinetics of the battery material.
      By analyzing X-ray images of lithium iron phosphate particles as they charged and discharged, researchers have shown that the movement of lithium ions within the material was nearly identical to computer simulations they had created earlier.  In each pair, the actual particles are on the left and the simulations are on the right.Courtesy of the researchers

      “Every little pixel in there is jumping from full to empty, full to empty. And we’re mapping that whole process, using our equations to understand how that’s happening,” Bazant says.

      The researchers also found that the patterns of lithium-ion flow that they observed could reveal spatial variations in the rate at which lithium ions are absorbed at each location on the particle surface.

      “It was a real surprise to us that we could learn the heterogeneities in the system — in this case, the variations in surface reaction rate — simply by looking at the images,” Bazant says. “There are regions that seem to be fast and others that seem to be slow.”

      Furthermore, the researchers showed that these differences in reaction rate were correlated with the thickness of the carbon coating on the surface of the lithium iron phosphate particles. That carbon coating is applied to lithium iron phosphate to help it conduct electricity — otherwise the material would conduct too slowly to be useful as a battery.

      “We discovered at the nano scale that variation of the carbon coating thickness directly controls the rate, which is something you could never figure out if you didn’t have all of this modeling and image analysis,” Bazant says.

      The findings also offer quantitative support for a hypothesis Bazant formulated several years ago: that the performance of lithium iron phosphate electrodes is limited primarily by the rate of coupled ion-electron transfer at the interface between the solid particle and the carbon coating, rather than the rate of lithium-ion diffusion in the solid.

      Optimized materials

      The results from this study suggest that optimizing the thickness of the carbon layer on the electrode surface could help researchers to design batteries that would work more efficiently, the researchers say.

      “This is the first study that’s been able to directly attribute a property of the battery material with a physical property of the coating,” Bazant says. “The focus for optimizing and designing batteries should be on controlling reaction kinetics at the interface of the electrolyte and electrode.”

      “This publication is the culmination of six years of dedication and collaboration,” Storey says. “This technique allows us to unlock the inner workings of the battery in a way not previously possible. Our next goal is to improve battery design by applying this new understanding.”  

      In addition to using this type of analysis on other battery materials, Bazant anticipates that it could be useful for studying pattern formation in other chemical and biological systems.

      This work was supported by the Toyota Research Institute through the Accelerated Materials Design and Discovery program. More

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      in Environment

      Harnessing hydrogen’s potential to address long-haul trucking emissions

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      The transportation of goods forms the basis of today’s globally distributed supply chains, and long-haul trucking is a central and critical link in this complex system. To meet climate goals around the world, it is necessary to develop decarbonized solutions to replace diesel powertrains, but given trucking’s indispensable and vast role, these solutions must be both economically viable and practical to implement. While hydrogen-based options, as an alternative to diesel, have the potential to become a promising decarbonization strategy, hydrogen has significant limitations when it comes to delivery and refueling.These roadblocks, combined with hydrogen’s compelling decarbonization potential, are what motivated a team of MIT researchers led by William H. Green, the Hoyt Hottel Professor in Chemical Engineering, to explore a cost-effective way to transport and store hydrogen using liquid organic hydrogen carriers (LOHCs). The team is developing a disruptive technology that allows LOHCs to not only deliver the hydrogen to the trucks, but also store the hydrogen onboard.Their findings were recently published in Energy and Fuels, a peer-reviewed journal of the American Chemical Society, in a paper titled “Perspective on Decarbonizing Long-Haul Trucks Using Onboard Dehydrogenation of Liquid Organic Hydrogen Carriers.” The MIT team is led by Green, and includes graduate students Sayandeep Biswas and Kariana Moreno Sader. Their research is supported by the MIT Climate and Sustainability Consortium (MCSC) through its Seed Awards program and MathWorks, and ties into the work within the MCSC’s Tough Transportation Modes focus area.An “onboard” approachCurrently, LOHCs, which work within existing retail fuel distribution infrastructure, are used to deliver hydrogen gas to refueling stations, where it is then compressed and delivered onto trucks equipped with hydrogen fuel cell or combustion engines.“This current approach incurs significant energy loss due to endothermic hydrogen release and compression at the retail station” says Green. “To address this, our work is exploring a more efficient application, with LOHC-powered trucks featuring onboard dehydrogenation.”To implement such a design, the team aims to modify the truck’s powertrain (the system inside a vehicle that produces the energy to propel it forward) to allow onboard hydrogen release from the LOHCs, using waste heat from the engine exhaust to power the “dehydrogenation” process. 

      Proposed process flow diagram for onboard dehydrogenation. Component sizes are not to scale and have been enlarged for illustrative purposes.

      Image courtesy of the Green Group.

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      The dehydrogenation process happens within a high-temperature reactor, which continually receives hydrogen-rich LOHCs from the fuel storage tank. Hydrogen released from the reactor is fed to the engine, after passing through a separator to remove any lingering LOHC. On its way to the engine, some of the hydrogen gets diverted to a burner to heat the reactor, which helps to augment the reactor heating provided by the engine exhaust gases.Acknowledging and addressing hydrogen’s drawbacksThe team’s paper underscores that current uses of hydrogen, including LOHC systems, to decarbonize the trucking sector have drawbacks. Regardless of technical improvements, these existing options remain prohibitively expensive due to the high cost of retail hydrogen delivery.“We present an alternative option that addresses a lot of the challenges and seems to be a viable way in which hydrogen can be used in this transportation context,” says Biswas, who was recently elected to the MIT Martin Family Society of Fellows for Sustainability for his work in this area. “Hydrogen, when used through LOHCs, has clear benefits for long-hauling, such as scalability and fast refueling time. There is also an enormous potential to improve delivery and refueling to further reduce cost, and our system is working to do that.”“Utilizing hydrogen is an option that is globally accessible, and could be extended to countries like the one where I am from,” says Moreno Sader, who is originally from Colombia. “Since it synergizes with existing infrastructure, large upfront investments are not necessary. The global applicability is huge.”Moreno Sader is a MathWorks Fellow, and, along with the rest of the team, has been using MATLAB tools to develop models and simulations for this work.Different sectors coming togetherDecarbonizing transportation modes, including long-haul trucking, requires expertise and perspectives from different industries — an approach that resonates with the MCSC’s mission.The team’s groundbreaking research into LOHC-powered trucking is among several projects supported by the MCSC within its Tough Transportation Modes focus area, led by postdoc Impact Fellow Danika MacDonell. The MCSC-supported projects were chosen to tackle a complementary set of societally important and industry-relevant challenges to decarbonizing heavy-duty transportation, which span a range of sectors and solution pathways. Other projects focus, for example, on logistics optimization for electrified trucking fleets, or air quality and climate impacts of ammonia-powered shipping.The MCSC works to support and amplify the impact of these projects by engaging the research teams with industry partners from a variety of sectors. In addition, the MCSC pursues a collective multisectoral approach to decarbonizing transportation by facilitating shared learning across the different projects through regular cross-team discussion.The research led by Green celebrates this cross-sector theme by integrating industry-leading computing tools provided by MathWorks with cutting-edge developments in chemical engineering, as well as industry-leading commercial LOHC reactor demonstrations, to build a compelling vision for cost-effective LOHC-powered trucking.The review and research conducted in the Energy and Fuels article lays the groundwork for further investigations into LOHC-powered truck design. The development of such a vehicle — with a power-dense, efficient, and robust onboard hydrogen release system — requires dedicated investigations and further optimization of core components geared specifically toward the trucking application. More

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      in Energy

      Making aviation fuel from biomass

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      In 2021, nearly a quarter of the world’s carbon dioxide emissions came from the transportation sector, with aviation being a significant contributor. While the growing use of electric vehicles is helping to clean up ground transportation, today’s batteries can’t compete with fossil fuel-derived liquid hydrocarbons in terms of energy delivered per pound of weight — a major concern when it comes to flying. Meanwhile, based on projected growth in travel demand, consumption of jet fuel is projected to double between now and 2050 — the year by which the international aviation industry has pledged to be carbon neutral.

      Many groups have targeted a 100 percent sustainable hydrocarbon fuel for aircraft, but without much success. Part of the challenge is that aviation fuels are so tightly regulated. “This is a subclass of fuels that has very specific requirements in terms of the chemistry and the physical properties of the fuel, because you can’t risk something going wrong in an airplane engine,” says Yuriy Román-Leshkov, the Robert T. Haslam Professor of Chemical Engineering. “If you’re flying at 30,000 feet, it’s very cold outside, and you don’t want the fuel to thicken or freeze. That’s why the formulation is very specific.”

      Aviation fuel is a combination of two large classes of chemical compounds. Some 75 to 90 percent of it is made up of “aliphatic” molecules, which consist of long chains of carbon atoms linked together. “This is similar to what we would find in diesel fuels, so it’s a classic hydrocarbon that is out there,” explains Román-Leshkov. The remaining 10 to 25 percent consists of “aromatic” molecules, each of which includes at least one ring made up of six connected carbon atoms.

      In most transportation fuels, aromatic hydrocarbons are viewed as a source of pollution, so they’re removed as much as possible. However, in aviation fuels, some aromatic molecules must remain because they set the necessary physical and combustion properties of the overall mixture. They also perform one more critical task: They ensure that seals between various components in the aircraft’s fuel system are tight. “The aromatics get absorbed by the plastic seals and make them swell,” explains Román-Leshkov. “If for some reason the fuel changes, so can the seals, and that’s very dangerous.”

      As a result, aromatics are a necessary component — but they’re also a stumbling block in the move to create sustainable aviation fuels, or SAFs. Companies know how to make the aliphatic fraction from inedible parts of plants and other renewables, but they haven’t yet developed an approved method of generating the aromatic fraction from sustainable sources. As a result, there’s a “blending wall,” explains Román-Leshkov. “Since we need that aromatic content — regardless of its source — there will always be a limit on how much of the sustainable aliphatic hydrocarbons we can use without changing the properties of the mixture.” He notes a similar blending wall with gasoline. “We have a lot of ethanol, but we can’t add more than 10 percent without changing the properties of the gasoline. In fact, current engines can’t handle even 15 percent ethanol without modification.”

      No shortage of renewable source material — or attempts to convert it

      For the past five years, understanding and solving the SAF problem has been the goal of research by Román-Leshkov and his MIT team — Michael L. Stone PhD ’21, Matthew S. Webber, and others — as well as their collaborators at Washington State University, the National Renewable Energy Laboratory (NREL), and the Pacific Northwest National Laboratory. Their work has focused on lignin, a tough material that gives plants structural support and protection against microbes and fungi. About 30 percent of the carbon in biomass is in lignin, yet when ethanol is generated from biomass, the lignin is left behind as a waste product.

      Despite valiant efforts, no one has found an economically viable, scalable way to turn lignin into useful products, including the aromatic molecules needed to make jet fuel 100 percent sustainable. Why not? As Román-Leshkov says, “It’s because of its chemical recalcitrance.” It’s difficult to make it chemically react in useful ways. As a result, every year millions of tons of waste lignin are burned as a low-grade fuel, used as fertilizer, or simply thrown away.

      Understanding the problem requires understanding what’s happening at the atomic level. A single lignin molecule — the starting point of the challenge — is a big “macromolecule” made up of a network of many aromatic rings connected by oxygen and hydrogen atoms. Put simply, the key to converting lignin into the aromatic fraction of SAF is to break that macromolecule into smaller pieces while in the process getting rid of all of the oxygen atoms.

      In general, most industrial processes begin with a chemical reaction that prevents the subsequent upgrading of lignin: As the lignin is extracted from the biomass, the aromatic molecules in it react with one another, linking together to form strong networks that won’t react further. As a result, the lignin is no longer useful for making aviation fuels.

      To avoid that outcome, Román-Leshkov and his team utilize another approach: They use a catalyst to induce a chemical reaction that wouldn’t normally occur during extraction. By reacting the biomass in the presence of a ruthenium-based catalyst, they are able to remove the lignin from the biomass and produce a black liquid called lignin oil. That product is chemically stable, meaning that the aromatic molecules in it will no longer react with one another.

      So the researchers have now successfully broken the original lignin macromolecule into fragments that contain just one or two aromatic rings each. However, while the isolated fragments don’t chemically react, they still contain oxygen atoms. Therefore, one task remains: finding a way to remove the oxygen atoms.

      In fact, says Román-Leshkov, getting from the molecules in the lignin oil to the targeted aromatic molecules required them to accomplish three things in a single step: They needed to selectively break the carbon-oxygen bonds to free the oxygen atoms; they needed to avoid incorporating noncarbon atoms into the aromatic rings (for example, atoms from the hydrogen gas that must be present for all of the chemical transformations to occur); and they needed to preserve the carbon backbone of the molecule — that is, the series of linked carbon atoms that connect the aromatic rings that remain.

      Ultimately, Román-Leshkov and his team found a special ingredient that would do the trick: a molybdenum carbide catalyst. “It’s actually a really amazing catalyst because it can perform those three actions very well,” says Román-Leshkov. “In addition to that, it’s extremely resistant to poisons. Plants can contain a lot of components like proteins, salts, and sulfur, which often poison catalysts so they don’t work anymore. But molybdenum carbide is very robust and isn’t strongly influenced by such impurities.”

      Trying it out on lignin from poplar trees

      To test their approach in the lab, the researchers first designed and built a specialized “trickle-bed” reactor, a type of chemical reactor in which both liquids and gases flow downward through a packed bed of catalyst particles. They then obtained biomass from a poplar, a type of tree known as an “energy crop” because it grows quickly and doesn’t require a lot of fertilizer.

      To begin, they reacted the poplar biomass in the presence of their ruthenium-based catalyst to extract the lignin and produce the lignin oil. They then flowed the oil through their trickle-bed reactor containing the molybdenum carbide catalyst. The mixture that formed contained some of the targeted product but also a lot of others that still contained oxygen atoms.

      Román-Leshkov notes that in a trickle-bed reactor, the time during which the lignin oil is exposed to the catalyst depends entirely on how quickly it drips down through the packed bed. To increase the exposure time, they tried passing the oil through the same catalyst twice. However, the distribution of products that formed in the second pass wasn’t as they had predicted based on the outcome of the first pass.

      With further investigation, they figured out why. The first time the lignin oil drips through the reactor, it deposits oxygen onto the catalyst. The deposition of the oxygen changes the behavior of the catalyst such that certain products appear or disappear — with the temperature being critical. “The temperature and oxygen content set the condition of the catalyst in the first pass,” says Román-Leshkov. “Then, on the second pass, the oxygen content in the flow is lower, and the catalyst can fully break the remaining carbon-oxygen bonds.” The process can thus operate continuously: Two separate reactors containing independent catalyst beds would be connected in series, with the first pretreating the lignin oil and the second removing any oxygen that remains.

      Based on a series of experiments involving lignin oil from poplar biomass, the researchers determined the operating conditions yielding the best outcome: 350 degrees Celsius in the first step and 375 C in the second step. Under those optimized conditions, the mixture that forms is dominated by the targeted aromatic products, with the remainder consisting of small amounts of other jet-fuel aliphatic molecules and some remaining oxygen-containing molecules. The catalyst remains stable while generating more than 87 percent (by weight) of aromatic molecules.

      “When we do our chemistry with the molybdenum carbide catalyst, our total carbon yields are nearly 85 percent of the theoretical carbon yield,” says Román-Leshkov. “In most lignin-conversion processes, the carbon yields are very low, on the order of 10 percent. That’s why the catalysis community got very excited about our results — because people had not seen carbon yields as high as the ones we generated with this catalyst.”

      There remains one key question: Does the mixture of components that forms have the properties required for aviation fuel? “When we work with these new substrates to make new fuels, the blend that we create is different from standard jet fuel,” says Román-Leshkov. “Unless it has the exact properties required, it will not qualify for certification as jet fuel.”

      To check their products, Román-Leshkov and his team send samples to Washington State University, where a team operates a combustion lab devoted to testing fuels. Results from initial testing of the composition and properties of the samples have been encouraging. Based on the composition and published prescreening tools and procedures, the researchers have made initial property predictions for their samples, and they looked good. For example, the freezing point, viscosity, and threshold sooting index are predicted to be lower than the values for conventional aviation aromatics. (In other words, their material should flow more easily and be less likely to freeze than conventional aromatics while also generating less soot in the atmosphere when they burn.) Overall, the predicted properties are near to or more favorable than those of conventional fuel aromatics.

      Next steps

      The researchers are continuing to study how their sample blends behave at different temperatures and, in particular, how well they perform that key task: soaking into and swelling the seals inside jet engines. “These molecules are not the typical aromatic molecules that you use in jet fuel,” says Román-Leshkov. “Preliminary tests with sample seals show that there’s no difference in how our lignin-derived aromatics swell the seals, but we need to confirm that. There’s no room for error.”

      In addition, he and his team are working with their NREL collaborators to scale up their methods. NREL has much larger reactors and other infrastructure needed to produce large quantities of the new sustainable blend. Based on the promising results thus far, the team wants to be prepared for the further testing required for the certification of jet fuels. In addition to testing samples of the fuel, the full certification procedure calls for demonstrating its behavior in an operating engine — “not while flying, but in a lab,” clarifies Román-Leshkov. In addition to requiring large samples, that demonstration is both time-consuming and expensive — which is why it’s the very last step in the strict testing required for a new sustainable aviation fuel to be approved.

      Román-Leshkov and his colleagues are now exploring the use of their approach with other types of biomass, including pine, switchgrass, and corn stover (the leaves, stalks, and cobs left after corn is harvested). But their results with poplar biomass are promising. If further testing confirms that their aromatic products can replace the aromatics now in jet fuel, “the blending wall could disappear,” says Román-Leshkov. “We’ll have a means of producing all the components in aviation fuel from renewable material, potentially leading to aircraft fuel that’s 100 percent sustainable.”

      This research was initially funded by the Center for Bioenergy Innovation, a U.S. Department of Energy (DOE) Research Center supported by the Office of Biological and Environmental Research in the DOE Office of Science. More recent funding came from the DOE Bioenergy Technologies Office and from Eni S.p.A. through the MIT Energy Initiative. Michael L. Stone PhD ’21 is now a postdoc in chemical engineering at Stanford University. Matthew S. Webber is a graduate student in the Román-Leshkov group, now on leave for an internship at the National Renewable Energy Laboratory.

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

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      in Environment

      Harnessing synthetic biology to make sustainable alternatives to petroleum products

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      Reducing our reliance on fossil fuels is going to require a transformation in the way we make things. That’s because the hydrocarbons found in fuels like crude oil, natural gas, and coal are also in everyday items like plastics, clothing, and cosmetics.

      Now Visolis, founded by Deepak Dugar SM ’11, MBA ’13, PhD ’13, is combining synthetic biology with chemical catalysis to reinvent the way the world makes things — and reducing gigatons of greenhouse gas emissions in the process.

      The company — which uses a microbe to ferment biomass waste like wood chips and create a molecular building block called mevalonic acid — is more sustainably producing everything from car tires and cosmetics to aviation fuels by tweaking the chemical processes involved to make different byproducts.

      “We started with [the rubber component] isoprene as the main molecule we produce [from mevalonic acid], but we’ve expanded our platform with this unique combination of chemistry and biology that allows us to decarbonize multiple supply chains very rapidly and efficiently,” Dugar explains. “Imagine carbon-negative yoga pants. We can make that happen. Tires can be carbon-negative, personal care can lower its footprint — and we’re already selling into personal care. So in everything from personal care to apparel to industrial goods, our platform is enabling decarbonization of manufacturing.”

      “Carbon-negative” is a term Dugar uses a lot. Visolis has already partnered with some of the world’s largest consumers of isoprene, a precursor to rubber, and now Dugar wants to prove out the company’s process in other emissions-intensive industries.

      “Our process is carbon-negative because plants are taking CO2 from the air, and we take that plant matter and process it into something structural, like synthetic rubber, which is used for things like roofing, tires, and other applications,” Dugar explains. “Generally speaking, most of that material at the end of its life gets recycled, for example to tarmac or road, or, worst-case scenario, it ends up in a landfill, so the CO2 that was captured by the plant matter stays captured in the materials. That means our production can be carbon-negative depending on the emissions of the production process. That allows us to not only reduce climate change but start reversing it. That was an insight I had about 10 years ago at MIT.”

      Finding a path

      For his PhD, Dugar explored the economics of using microbes to make high-octane gas additives. He also took classes at the MIT Sloan School of Management on sustainability and entrepreneurship, including the particularly influential course 15.366 (Climate and Energy Ventures). The experience inspired him to start a company.

      “I wanted to work on something that could have the largest climate impact, and that was replacing petroleum,” Dugar says. “It was about replacing petroleum not just as a fuel but as a material as well. Everything from the clothes we wear to the furniture we sit on is often made using petroleum.”

      By analyzing recent advances in synthetic biology and making some calculations from first principles, Dugar decided that a microbial approach to cleaning up the production of rubber was viable. He participated in the MIT Clean Energy Prize and worked with others at MIT to prove out the idea. But it was still just an idea. After graduation, he took a consulting job at a large company, spending his nights and weekends renting lab space to continue trying to make his sustainable rubber a reality.

      After 18 months, by applying engineering concepts like design-for-scale to synthetic biology, Dugar was able to develop a microbe that met 80 percent of his criteria for making an intermediate molecule called mevalonic acid. From there, he developed a chemical catalysis process that converted mevalonic acid to isoprene, the main component of natural rubber. Visolis has since patented other chemical conversion processes that turn mevalonic acid to aviation fuel, polymers, and fabrics.

      Dugar left his consulting job in 2014 and was awarded a fellowship to work on Visolis full-time at the Lawrence Berkeley National Lab via Activate, an incubator empowering scientists to reinvent the world.

      From rubber to jet fuels

      Today, in addition to isoprene, Visolis is selling skin care products through the brand Ameva Bio, which produces mevalonic acid-based creams by recycling plant byproducts created in other processes. The company offers refillable bottles and even offsets emissions from the shipping of its products.

      “We are working throughout the supply chain,” Dugar says. “It made sense to clean up the isoprene part of the rubber supply chain rather than the entire supply chain. But we’re also producing molecules for skin that are better for you, so you can put something much more sustainable and healthier on your body instead of petrochemicals. We launched Ameva to demonstrate that brands can leverage synthetic biology to turn carbon-negative ingredients into high-performing products.”

      Visolis is also starting the process of gaining regulatory approval for its sustainable aviation fuel, which Dugar believes could have the biggest climate impact of any of the company’s products by cleaning up the production of fuels for commercial flight.

      “We’re working with leading companies to help them decarbonize aviation” Dugar says. “If you look at the lifecycle of fuel, the current petroleum-based approach is we dig out hydrocarbons from the ground and burn it, emitting CO2 into the air. In our process, we take plant matter, which affixes to CO2 and captures renewable energy in those bonds, and then we transfer that into aviation fuel plus things like synthetic rubber, yoga pants, and other things that continue to hold the carbon. So, our factories can still operate at net zero carbon emissions.”

      Visolis is already generating millions of dollars in revenue, and Dugar says his goal is to scale the company rapidly now that its platform molecule has been validated.

      “We have been scaling our technology by 10 times every two to three years and are now looking to increase deployment of our technology at the same pace, which is very exciting.” Dugar says. “If you extrapolate that, very quickly you get to massive impact. That’s our goal.” More

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      in Energy

      Panel addresses technologies needed for a net-zero future

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      Five speakers at a recent public panel discussion hosted by the MIT Energy Initiative (MITEI) and introduced by Deputy Director for Science and Technology Robert Stoner tackled one of the thorniest, yet most critical, questions facing the world today: How can we achieve the ambitious goals set by governments around the globe, including the United States, to reach net zero emissions of greenhouse gases by mid-century?

      While the challenges are great, the panelists agreed, there is reason for optimism that these technological challenges can be solved. More uncertain, some suggested, are the social, economic, and political hurdles to bringing about the needed innovations.

      The speakers addressed areas where new or improved technologies or systems are needed if these ambitious goals are to be achieved. Anne White, aassociate provost and associate vice president for research administration and a professor of nuclear science and engineering at MIT, moderated the panel discussion. She said that achieving the ambitious net-zero goal “has to be accomplished by filling some gaps, and going after some opportunities.” In addressing some of these needs, she said the five topics chosen for the panel discussion were “places where MIT has significant expertise, and progress is already ongoing.”

      First of these was the heating and cooling of buildings. Christoph Reinhart, a professor of architecture and director of the Building Technology Program, said that currently about 1 percent of existing buildings are being retrofitted each year for energy efficiency and conversion from fossil-fuel heating systems to efficient electric ones — but that is not nearly enough to meet the 2050 net-zero target. “It’s an enormous task,” he said. To meet the goals, he said, would require increasing the retrofitting rate to 5 percent per year, and to require all new construction to be carbon neutral as well.

      Reinhart then showed a series of examples of how such conversions could take place using existing solar and heat pump technology, and depending on the configuration, how they could provide a payback to the homeowner within 10 years or less. However, without strong policy incentives the initial cost outlay for such a system, on the order of $50,000, is likely to put conversions out of reach of many people. Still, a recent survey found that 30 percent of homeowners polled said they would accept installation at current costs. While there is government money available for incentives for others, “we have to be very clever on how we spend all this money … and make sure that everybody is basically benefiting.”

      William Green, a professor of chemical engineering, spoke about the daunting challenge of bringing aviation to net zero. “More and more people like to travel,” he said, but that travel comes with carbon emissions that affect the climate, as well as air pollution that affects human health. The economic costs associated with these emissions, he said, are estimated at $860 per ton of jet fuel used — which is very close to the cost of the fuel itself. So the price paid by the airlines, and ultimately by the passengers, “is only about half of the true cost to society, and the other half is being borne by all of us, by the fact that it’s affecting the climate and it’s causing medical problems for people.”

      Eliminating those emissions is a major challenge, he said. Virtually all jet fuel today is fossil fuel, but airlines are starting to incorporate some biomass-based fuel, derived mostly from food waste. But even these fuels are not carbon-neutral, he said. “They actually have pretty significant carbon intensity.”

      But there are possible alternatives, he said, mostly based on using hydrogen produced by clean electricity, and making fuels out of that hydrogen by reacting it, for example, with carbon dioxide. This could indeed produce a carbon-neutral fuel that existing aircraft could use, but the process is costly, requiring a great deal of hydrogen, and ways of concentrating carbon dioxide. Other viable options also exist, but all would add significant expense, at least with present technology. “It’s going to cost a lot more for the passengers on the plane,” Green said, “But the society will benefit from that.”

      Increased electrification of heating and transportation in order to avoid the use of fossil fuels will place major demands on the existing electric grid systems, which have to perform a constant delicate balancing of production with demand. Anuradha Annaswamy, a senior research scientist in MIT’s mechanical engineering department, said “the electric grid is an engineering marvel.” In the United States it consists of 300,000 miles of transmission lines capable of carrying 470,000 megawatts of power.

      But with a projected doubling of energy from renewable sources entering the grid by 2030, and with a push to electrify everything possible — from transportation to buildings to industry — the load is not only increasing, but the patterns of both energy use and production are changing. Annaswamy said that “with all these new assets and decision-makers entering the picture, the question is how you can use a more sophisticated information layer that coordinates how all these assets are either consuming or producing or storing energy, and have that information layer coexist with the physical layer to make and deliver electricity in all these ways. It’s really not a simple problem.”

      But there are ways of addressing these complexities. “Certainly, emerging technologies in power electronics and control and communication can be leveraged,” she said. But she added that “This is not just a technology problem, really, it is something that requires technologists, economists, and policymakers to all come together.”

      As for industrial processes, Bilge Yildiz, a professor of nuclear science and engineering and materials science and engineering, said that “the synthesis of industrial chemicals and materials constitutes about 33 percent of global CO2 emissions at present, and so our goal is to decarbonize this difficult sector.” About half of all these industrial emissions come from the production of just four materials: steel, cement, ammonia, and ethylene, so there is a major focus of research on ways to reduce their emissions.

      Most of the processes to make these materials have changed little for more than a century, she said, and they are mostly heat-based processes that involve burning a lot of fossil fuel. But the heat can instead be provided from renewable electricity, which can also be used to drive electrochemical reactions in some cases as a substitute for the thermal reactions. Already, there are processes for making cement and steel that produce only about half the present carbon dioxide (CO2) emissions.

      The production of ammonia, which is widely used in fertilizer and other bulk chemicals, accounts for more greenhouse gas emissions than any other industrial source. The present thermochemical process could be replaced by an electrochemical process, she said. Similarly, the production of ethylene, as a feedstock for plastics and other materials, is the second-highest emissions producer, with three tons of carbon dioxide released for every ton of ethylene produced. Again, an electrochemical alternative method exists, but needs to be improved to be cost competitive.

      As the world moves toward electrification of industrial processes to eliminate fossil fuels, the need for emissions-free sources of electricity will continue to increase. One very promising potential addition to the range of carbon-free generation sources is fusion, a field in which MIT is a leader in developing a particularly promising technology that takes advantage of the unique properties of high-temperature superconducting (HTS) materials.

      Dennis Whyte, the director of MIT’s Plasma Science and Fusion Center, pointed out that despite global efforts to reduce CO2 emissions, “we use exactly the same percentage of carbon-based products to generate energy as 10 years ago, or 20 years ago.” To make a real difference in global emissions, “we need to make really massive amounts of carbon-free energy.”

      Fusion, the process that powers the sun, is a particularly promising pathway, because the fuel, derived from water, is virtually inexhaustible. By using recently developed HTS material to generate the powerful magnetic fields needed to produce a sustained fusion reaction, the MIT-led project, which led to a spinoff company called Commonwealth Fusion Systems, was able to radically reduce the required size of a fusion reactor, Whyte explained. Using this approach, the company, in collaboration with MIT, expects to have a fusion system that produces net energy by the middle of this decade, and be ready to build a commercial plant to produce power for the grid early in the next. Meanwhile, at least 25 other private companies are also attempting to commercialize fusion technology. “I think we can take some credit for helping to spawn what is essentially now a new industry in the United States,” Whyte said.

      Fusion offers the potential, along with existing solar and wind technologies, to provide the emissions-free power the world needs, Whyte says, but that’s only half the problem, the other part being how to get that power to where it’s needed, when it’s needed. “How do we adapt these new energy sources to be as compatible as possible with everything that we have already in terms of energy delivery?”

      Part of the way to find answers to that, he suggested, is more collaborative work on these issues that cut across disciplines, as well as more of the kinds of cross-cutting conversations and interactions that took place in this panel discussion. More

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      in Environment

      Advancing material innovation to address the polymer waste crisis

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      Products made from polymers — ranging from plastic bags to clothing to cookware to electronics — provide many comforts and support today’s standard of living, but since they do not decompose easily, they pose long-term environmental challenges. Developing polymers, a large class of materials, with a more sustainable life cycle is a critical step in making progress toward a green economy and addressing this piece of the global climate change crisis. The development of biodegradable polymers, however, remains limited by current biodegradation testing methods.

      To address this limitation, a team of MIT researchers led by Bradley D. Olsen, the Alexander and I. Michael Kasser (1960) Professor in the Department of Chemical Engineering, has developed an expansive biodegradation dataset to help determine whether or not a polymer is biodegradable.

      Their findings were recently published in The Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS), in a paper titled “High-Throughput Experimentation for Discovery of Biodegradable Polyesters.” The MIT team is led by Olsen and PhD candidates Katharina A. Fransen and Sarah H. M. Av-Ron, and also includes postdoc Dylan J. Walsh and undergraduate students Tess R. Buchanan, Dechen T. Rota, and Lana Van Note.

      “Despite polymer waste being a known and significant contributor to the climate crisis, the study of polymer biodegradation has been limited to a small number of polymers because current biodegradation testing methods are time- and resource-intensive,” says Olsen. “This limited scope slows new material innovation, so we are working to open that up to a much broader portfolio of materials.”

      Unique high-throughput approach

      The dataset Olsen’s team has developed, with support from the MIT Climate and Sustainability Consortium (MCSC), the Abdul Latif Jameel Water and Food Systems Lab (J-WAFS), and DIC Corporation, includes more than 600 distinct polyester chemistries.

      “The ingenuity of our work is pushing the screening to be high-throughput, which accelerates the pace of discovery,” says Av-Ron. High-throughput synthesis methods enable large quantities of samples to be screened rapidly, identifying products with the desired property or function you are looking for. In this case, the high-throughput approach was conducted using a method called clear-zone assay, which detects polymer biofragmentation and identifies polymer degrading bacteria. The biodegradation dataset can then lead to structure-property relationships, a concept central to materials science and engineering, where relationships between the chemical detail and property can be established, and used to build a biodegradation prediction model. When developing these models to predict biodegradation, the researchers were interested in looking into the potential linearity and nonlinearity of the relationships between structure and biodegradability.

      “We consider our scientific breakthrough to be having this large dataset, and the qualitative relationships and predictive models such a substantial  amount of data enabled,” adds Av-Ron. “It was captivating to figure out how to integrate the high complexity of polymer chemical representation with predictive machine-learning models. I was very excited to get a validation accuracy of 82 percent for one representation/model combination. With additional data we might be able to improve our predictions even more.”

      The team’s work focuses largely on polyesters; the development of biodegradable polyesters presents a key opportunity for addressing the polymer sustainability crisis and reducing the environmental burden of the polymer life cycle.

      One strain of bacteria, many chemistries

      The biodegradation test that these data create is accessible and cost-effective to put in place; initial industry feedback has been positive. The datasets are also more reproducible than many other standards in this space.

      “With our method, there is one strain of bacteria, so you know exactly what you’re testing,” says Av-Ron. This speaks to the uniqueness of the team’s approach.

      “When polymers are developed, normally the strength of the material is examined first, and then once the material is developed, whether or not it biodegrades comes second,” says Fransen.

      Olsen and his team are examining the opposite — developing the biodegradability screen first, to help filter and focus what to look for in a material. This way, the team’s infrastructure can assess a lot of different options, quickly.

      “There has been big movement recently in developing sustainable polymers,” concludes Fransen, “and having something like this that is quick, tangible, and relatively inexpensive, could add a lot of value to that community.”

      Fransen received a 2022 J-WAFS Fellowship for this work, and she and Av-Ron together won second place in the 2022 J-WAFS World Food Day Student Video Competition, as this research can be applied to creating more sustainable food packaging. More

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      in Energy

      Paula Hammond wins faculty’s Killian Award for 2023-24

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      Paula Hammond, a leading innovator in nanotechnology and head of MIT’s Department of Chemical Engineering, has been named the recipient of the 2023-2024 James R. Killian Jr. Faculty Achievement Award.

      Hammond, an MIT Institute Professor, was honored for her work designing novel polymers and nanomaterials, which have extensive applications in fields including medicine and energy.

      “Professor Hammond is a pioneer in nanotechnology research, with a program that spans from basic science to translational research in medicine and energy. She has introduced new approaches for the design and development of complex drug delivery systems for cancer treatment and non-invasive imaging,” according to the award citation, which was read at the May 17 faculty meeting by Laura Kiessling, the chair of the Killian Award Selection Committee and the Novartis Professor of Chemistry at MIT.

      Established in 1971 to honor MIT’s 10th president, James Killian, the Killian Award recognizes extraordinary professional achievements by an MIT faculty member.

      “I’ve been to past Killian Award lectures, and I’ve always thought these were the ultimate achievers at MIT in terms of their work and their science,” Hammond says. “I am incredibly honored and overwhelmed to be considered even close to a part of that group.”

      Hammond, who earned her bachelor’s degree from MIT in 1984, worked as an engineer before returning to the Institute four years later to earn a PhD, which she received in 1993. After two years as a postdoc at Harvard University, she returned to MIT again as a faculty member in 1995.

      “In a world where it isn’t always cool to be heavy into your science and your work, MIT was a place where I felt like I could just be completely myself, and that was an amazing thing,” she says.

      Since joining the faculty, Hammond has pioneered techniques for creating thin polymer films and other materials using layer-by-layer assembly. This approach can be used to build polymers with highly controlled architectures by alternately exposing a surface to positively and negatively charged particles.

      Hammond’s lab uses this technique to design materials for many different applications, including drug delivery, regenerative medicine, noninvasive imaging, and battery technology.

      Her accomplishments include designing nanoparticles that can zoom in on tumors and release their cargo when they associate with cancer cells. She has also developed nanoparticles and thin polymer films that can carry multiple drugs to a specific site and release the drugs in a controlled or staggered fashion. In recent years, much of that work has focused on potential treatments and diagnostics for ovarian cancer.

      “We’ve really had a focus on ovarian cancer over the past several years. My hope is that our work will move us in the direction of understanding how we can treat ovarian cancer, and, in collaboration with my colleagues, how we can detect it more effectively,” says Hammond, who is a member of MIT’s Koch Institute for Integrative Cancer Research.

      The award committee also cited Hammond’s record of service, both to MIT and the national scientific community. She currently serves on the President’s Council of Advisors on Science and Technology, and she is a former member of the U.S. Secretary of Energy Scientific Advisory Board. At MIT, Hammond chaired the Initiative on Faculty Race and Diversity, and co-chaired the Academic and Professional Relationships Working Group and the Implementation Team of the MIT response to the National Academies’ report entitled “Sexual Harassment of Women.”

      Among her many honors, Hammond is one of only 25 scientists who have been elected to the National Academies of Engineering, Sciences, and Medicine.

      Hammond has also been recognized for her dedication to teaching and mentoring. As a reflection of her excellence in those areas, Hammond was awarded the Irwin Sizer Award for Significant Improvements to MIT Education, the Henry Hill Lecturer Award in 2002, and the Junior Bose Faculty Award in 2000. She also co-chaired the recent Ad Hoc Committee on Faculty Advising and Mentoring, and has been selected as a “Committed to Caring” honoree for her work mentoring students and postdocs in her research group.

      “The Selection Committee is delighted to have this opportunity to honor Professor Paula Hammond, not only for her tremendous professional achievements and contributions, but also for her genuine warmth and humanity, her thoughtfulness and effective leadership, and her empathy and ethics. She is someone worth emulating. Indeed, simply put, she is the best of us,” the award committee wrote in its citation. More