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      in Environment

      Uncovering how biomes respond to climate change

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      Before Leila Mirzagholi arrived at MIT’s Department of Civil and Environmental Engineering (CEE) to begin her postdoc appointment, she had spent most of her time in academia building cosmological models to detect properties of gravitational waves in the cosmos.

      But as a member of Assistant Professor César Terrer’s lab in CEE, Mirzagholi uses her physics and mathematical background to improve our understanding of the different factors that influence how much carbon land ecosystems can store under climate change.

      “What was always important to me was thinking about how to solve a problem and putting all the pieces together and building something from scratch,” Mirzagholi says, adding this was one of the reasons that it was possible for her to switch fields — and what drives her today as a climate scientist.

      Growing up in Iran, Mirzagholi knew she wanted to be a scientist from an early age. As a kid, she became captivated by physics, spending most of her free time in a local cultural center that hosted science events. “I remember in that center there was an observatory that held observational tours and it drew me into science,” says Mirzgholi. She also remembers a time when she was a kid watching the science fiction film “Contact” that introduces a female scientist character who finds evidence of extraterrestrial life and builds a spaceship to make first contact: “After that movie my mind was set on pursuing astrophysics.”

      With the encouragement of her parents to develop a strong mathematical background before pursuing physics, she earned a bachelor’s degree in mathematics from Tehran University. Then she completed a one-year master class in mathematics at Utrecht University before completing her PhD in theoretical physics at Max Planck Institute for Astrophysics in Munich. There, Mirzgholi’s thesis focused on developing cosmological models with a focus on phenomenological aspects like propagation of gravitational waves on the cosmic microwave background.

      Midway through her PhD, Mirzgholi became discouraged with building models to explain the dynamics of the early universe because there is little new data. “It starts to get personal and becomes a game of: ‘Is it my model or your model?’” she explains. She grew frustrated not knowing when the models she’d built would ever be tested.

      It was at this time that Mirzgholi started reading more about the topics of climate change and climate science. “I was really motivated by the problems and the nature of the problems, especially to make global terrestrial ecology more quantitative,” she says. She also liked the idea of contributing to a global problem that we are all facing. She started to think, “maybe I can do my part, I can work on research beneficial for society and the planet.”

      She made the switch following her PhD and started as a postdoc in the Crowther Lab at ETH Zurich, working on understanding the effects of environmental changes on global vegetation activity. After a stint at ETH, where her colleagues collaborated on projects with the Terrer Lab, she relocated to Cambridge, Massachusetts, to join the lab and CEE.

      Her latest article in Science, which was published in July and co-authored by researchers from ETH, shows how global warming affects the timing of autumn leaf senescence. “It’s important to understand the length of the growing season, and how much the forest or other biomes will have the capacity to take in carbon from the atmosphere.” Using remote sensing data, she was able to understand when the growing season will end under a warming climate. “We distinguish two dates — when autumn is onsetting and the leaves are starting to turn yellow, versus when the leaves are 50 percent yellow — to represent the progression of leaf senescence,” she says.

      In the context of rising temperature, when the warming is happening plays a crucial role. If warming temperatures happen before the summer solstice, it triggers trees to begin their seasonal cycles faster, leading to reduced photosynthesis, ending in an earlier autumn. On the other hand, if the warming happens after the summer solstice, it delays the discoloration process, making autumn last longer. “For every degree Celsius of pre-solstice warming, the onset of leaf senescence advances by 1.9 days, while each degree Celsius of post-solstice warming delays the senescence process by 2.6 days,” she explains. Understanding the timing of autumn leaf senescence is essential in efforts to predict carbon storage capacity when modeling global carbon cycles.

      Another problem she’s working on in the Terrer Lab is discovering how deforestation is changing our local climate. How much is it cooling or warming the temperature, and how is the hydrological cycle changing because of deforestation? Investigating these questions will give insight into how much we can depend on natural solutions for carbon uptake to help mitigate climate change. “Quantitatively, we want to put a number to the amount of carbon uptake from various natural solutions, as opposed to other solutions,” she says.

      With year-and-a-half left in her postdoc appointment, Mirzagholi has begun considering her next career steps. She likes the idea of applying to climate scientist jobs in industry or national labs, as well as tenure track faculty positions. Whether she pursues a career in academia or industry, Mirzagholi aims to continue conducting fundamental climate science research. Her multidisciplinary background in physics, mathematics, and climate science has given her a multifaceted perspective, which she applies to every research problem.

      “Looking back, I’m grateful for all my educational experiences from spending time in the cultural center as a kid, my background in physics, the support from colleagues at the Crowther lab at ETH who facilitated my transition from physics to ecology, and now working at MIT alongside Professor Terrer, because it’s shaped my career path and the researcher I am today.” More

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      in Environment

      Explained: The 1.5 C climate benchmark

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      The summer of 2023 has been a season of weather extremes.

      In June, uncontrolled wildfires ripped through parts of Canada, sending smoke into the U.S. and setting off air quality alerts in dozens of downwind states. In July, the world set the hottest global temperature on record, which it held for three days in a row, then broke again on day four.

      From July into August, unrelenting heat blanketed large parts of Europe, Asia, and the U.S., while India faced a torrential monsoon season, and heavy rains flooded regions in the northeastern U.S. And most recently, whipped up by high winds and dry vegetation, a historic wildfire tore through Maui, devastating an entire town.

      These extreme weather events are mainly a consequence of climate change driven by humans’ continued burning of coal, oil, and natural gas. Climate scientists agree that extreme weather such as what people experienced this summer will likely grow more frequent and intense in the coming years unless something is done, on a persistent and planet-wide scale, to rein in global temperatures.

      Just how much reining-in are they talking about? The number that is internationally agreed upon is 1.5 degrees Celsius. To prevent worsening and potentially irreversible effects of climate change, the world’s average temperature should not exceed that of preindustrial times by more than 1.5 degrees Celsius (2.7 degrees Fahrenheit).

      As more regions around the world face extreme weather, it’s worth taking stock of the 1.5-degree bar, where the planet stands in relation to this threshold, and what can be done at the global, regional, and personal level, to “keep 1.5 alive.”

      Why 1.5 C?

      In 2015, in response to the growing urgency of climate impacts, nearly every country in the world signed onto the Paris Agreement, a landmark international treaty under which 195 nations pledged to hold the Earth’s temperature to “well below 2 degrees Celsius above pre-industrial levels,” and going further, aim to “limit the temperature increase to 1.5 degrees Celsius above pre-industrial levels.”

      The treaty did not define a particular preindustrial period, though scientists generally consider the years from 1850 to 1900 to be a reliable reference; this time predates humans’ use of fossil fuels and is also the earliest period when global observations of land and sea temperatures are available. During this period, the average global temperature, while swinging up and down in certain years, generally hovered around 13.5 degrees Celsius, or 56.3 degrees Fahrenheit.

      The treaty was informed by a fact-finding report which concluded that, even global warming of 1.5 degrees Celsius above the preindustrial average, over an extended, decades-long period, would lead to high risks for “some regions and vulnerable ecosystems.” The recommendation then, was to set the 1.5 degrees Celsius limit as a “defense line” — if the world can keep below this line, it potentially could avoid the more extreme and irreversible climate effects that would occur with a 2 degrees Celsius increase, and for some places, an even smaller increase than that.

      But, as many regions are experiencing today, keeping below the 1.5 line is no guarantee of avoiding extreme, global warming effects.

      “There is nothing magical about the 1.5 number, other than that is an agreed aspirational target. Keeping at 1.4 is better than 1.5, and 1.3 is better than 1.4, and so on,” says Sergey Paltsev, deputy director of MIT’s Joint Program on the Science and Policy of Global Change. “The science does not tell us that if, for example, the temperature increase is 1.51 degrees Celsius, then it would definitely be the end of the world. Similarly, if the temperature would stay at 1.49 degrees increase, it does not mean that we will eliminate all impacts of climate change. What is known: The lower the target for an increase in temperature, the lower the risks of climate impacts.”

      How close are we to 1.5 C?

      In 2022, the average global temperature was about 1.15 degrees Celsius above preindustrial levels. According to the World Meteorological Organization (WMO), the cyclical weather phenomenon La Niña recently contributed to temporarily cooling and dampening the effects of human-induced climate change. La Niña lasted for three years and ended around March of 2023.

      In May, the WMO issued a report that projected a significant likelihood (66 percent) that the world would exceed the 1.5 degrees Celsius threshold in the next four years. This breach would likely be driven by human-induced climate change, combined with a warming El Niño — a cyclical weather phenomenon that temporarily heats up ocean regions and pushes global temperatures higher.

      This summer, an El Niño is currently underway, and the event typically raises global temperatures in the year after it sets in, which in this case would be in 2024. The WMO predicts that, for each of the next four years, the global average temperature is likely to swing between 1.1 and 1.8 degrees Celsius above preindustrial levels.

      Though there is a good chance the world will get hotter than the 1.5-degree limit as the result of El Niño, the breach would be temporary, and for now, would not have failed the Paris Agreement, which aims to keep global temperatures below the 1.5-degree limit over the long term (averaged over several decades rather than a single year).

      “But we should not forget that this is a global average, and there are variations regionally and seasonally,” says Elfatih Eltahir, the H.M. King Bhumibol Professor and Professor of Civil and Environmental Engineering at MIT. “This year, we had extreme conditions around the world, even though we haven’t reached the 1.5 C threshold. So, even if we control the average at a global magnitude, we are going to see events that are extreme, because of climate change.”

      More than a number

      To hold the planet’s long-term average temperature to below the 1.5-degree threshold, the world will have to reach net zero emissions by the year 2050, according to the Intergovernmental Panel on Climate Change (IPCC). This means that, in terms of the emissions released by the burning of coal, oil, and natural gas, the entire world will have to remove as much as it puts into the atmosphere.

      “In terms of innovations, we need all of them — even those that may seem quite exotic at this point: fusion, direct air capture, and others,” Paltsev says.

      The task of curbing emissions in time is particularly daunting for the United States, which generates the most carbon dioxide emissions of any other country in the world.

      “The U.S.’s burning of fossil fuels and consumption of energy is just way above the rest of the world. That’s a persistent problem,” Eltahir says. “And the national statistics are an aggregate of what a lot of individuals are doing.”

      At an individual level, there are things that can be done to help bring down one’s personal emissions, and potentially chip away at rising global temperatures.

      “We are consumers of products that either embody greenhouse gases, such as meat, clothes, computers, and homes, or we are directly responsible for emitting greenhouse gases, such as when we use cars, airplanes, electricity, and air conditioners,” Paltsev says. “Our everyday choices affect the amount of emissions that are added to the atmosphere.”

      But to compel people to change their emissions, it may be less about a number, and more about a feeling.

      “To get people to act, my hypothesis is, you need to reach them not just by convincing them to be good citizens and saying it’s good for the world to keep below 1.5 degrees, but showing how they individually will be impacted,” says Eltahir, who specializes on the study of regional climates, focusing on how climate change impacts the water cycle and frequency of extreme weather such as heat waves.

      “True climate progress requires a dramatic change in how the human system gets its energy,” Paltsev says. “It is a huge undertaking. Are you ready personally to make sacrifices and to change the way of your life? If one gets an honest answer to that question, it would help to understand why true climate progress is so difficult to achieve.” More

    • 150 Shares159 Views

      in Environment

      3 Questions: Boosting concrete’s ability to serve as a natural “carbon sink”

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      Damian Stefaniuk is a postdoc at the MIT Concrete Sustainability Hub (CSHub). He works with MIT professors Franz-Josef Ulm and Admir Masic of the MIT Department of Civil and Environmental Engineering (CEE) to investigate multifunctional concrete. Here, he provides an overview of carbonation in cement-based products, a brief explanation of why understanding carbonation in the life cycle of cement products is key for assessing their environmental impact, and an update on current research to bolster the process.

      Q: What is carbonation and why is it important for thinking about concrete from a life-cycle perspective?

      A: Carbonation is the reaction between carbon dioxide (CO2) and certain compounds in cement-based products, occurring during their use phase and end of life. It forms calcium carbonate (CaCO3) and has important implications for neutralizing the GHG [greenhouse gas] emissions and achieving carbon neutrality in the life cycle of concrete.

      Firstly, carbonation causes cement-based products to act as natural carbon sinks, sequestering CO2 from the air and storing it permanently. This helps mitigate the carbon emissions associated with the production of cement, reducing their overall carbon footprint.

      Secondly, carbonation affects concrete properties. Early-stage carbonation may increase the compressive strength of cement-based products, enhancing their durability and structural performance. However, late-stage carbonation can impact corrosion resistance in steel-reinforced concrete due to reduced alkalinity.

      Considering carbonation in the life cycle of cement-based products is crucial for accurately assessing their environmental impact. Understanding and leveraging carbonation can help industry reduce carbon emissions and maximize carbon sequestration potential. Paying close attention to it in the design process aids in creating durable and corrosion-resistant structures, contributing to longevity and overall sustainability.

      Q: What are some ongoing global efforts to force carbonation?

      A: Some ongoing efforts to force carbonation in concrete involve artificially increasing the amount of CO2 gas present during the early-stage hydration of concrete. This process, known as forced carbonation, aims to accelerate the carbonation reaction and its associated benefits.

      Forced carbonation is typically applied to precast concrete elements that are produced in artificially CO2-rich environments. By exposing fresh concrete to higher concentrations of CO2 during curing, the carbonation process can be expedited, resulting in potential improvements in strength, reduced water absorption, improved resistance to chloride permeability, and improved performance during freeze-thaw. At the same time, it can be difficult to quantify how much CO2 is absorbed and released because of the process.

      These efforts to induce early-stage carbonation through forced carbonation represent the industry’s focus on optimizing concrete performance and environmental impacts. By exploring methods to enhance the carbonation process, researchers and practitioners seek to more efficiently harness its benefits, such as increasing strength and sequestering CO2.

      It is important to note that forced carbonation requires careful implementation and monitoring to ensure desired outcomes. The specific procedures and conditions vary based on the application and intended goals, highlighting the need for expertise and controlled environments.

      Overall, ongoing efforts in forced carbonation contribute to the continuous development of concrete technology, aiming to improve its properties and reduce its carbon footprint throughout the life cycle of the material.

      Q: What is chemically-induced pre-cure carbonation, and what implications does it have?

      A: Chemically-induced pre-cure carbonation (CIPCC) is a method developed by the MIT CSHub to mineralize and permanently store CO2 in cement. Unlike traditional forced carbonation methods, CIPCC introduces CO2 into the concrete mix as a solid powder, specifically sodium bicarbonate. This approach addresses some of the limitations of current carbon capture and utilization technologies.

      The implications of CIPCC are significant. Firstly, it offers convenience for cast-in-place applications, making it easier to incorporate CO2 use in concrete projects. Unlike some other approaches, CIPCC allows for precise control over the quantity of CO2 sequestered in the concrete. This ensures accurate carbonation and facilitates better management of the storage process. CIPCC also builds on previous research regarding amorphous hydration phases, providing an additional mechanism for CO2 sequestration in cement-based products. These phases carbonate through CIPCC, contributing to the overall carbon sequestration capacity of the material.

      Furthermore, early-stage pre-cure carbonation shows promise as a pathway for concrete to permanently sequester a controlled and precise quantity of CO2. Our recent paper in PNAS Nexus suggests that it could theoretically offset at least 40 percent of the calcination emissions associated with cement production, when anticipating advances in the lower-emissions production of sodium bicarbonate. We also found that up to 15 percent of cement (by weight) could be substituted with sodium bicarbonate without compromising the mechanical performance of a given mix. Further research is needed to evaluate long-term effects of this process to explore the potential life-cycle savings and impacts of carbonation.

      CIPCC offers not only environmental benefits by reducing carbon emissions, but also practical advantages. The early-stage strength increase observed in real-world applications could expedite construction timelines by allowing concrete to reach its full strength faster.

      Overall, CIPCC demonstrates the potential for more efficient and controlled CO2 sequestration in concrete. It represents an important development in concrete sustainability, emphasizing the need for further research and considering the material’s life-cycle impacts.

      This research was carried out by MIT CSHub, which is sponsored by the Concrete Advancement Foundation and the Portland Cement Association. More

    • 88 Shares179 Views

      in Environment

      The curse of variety in transportation systems

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      Cathy Wu has always delighted in systems that run smoothly. In high school, she designed a project to optimize the best route for getting to class on time. Her research interests and career track are evidence of a propensity for organizing and optimizing, coupled with a strong sense of responsibility to contribute to society instilled by her parents at a young age.

      As an undergraduate at MIT, Wu explored domains like agriculture, energy, and education, eventually homing in on transportation. “Transportation touches each of our lives,” she says. “Every day, we experience the inefficiencies and safety issues as well as the environmental harms associated with our transportation systems. I believe we can and should do better.”

      But doing so is complicated. Consider the long-standing issue of traffic systems control. Wu explains that it is not one problem, but more accurately a family of control problems impacted by variables like time of day, weather, and vehicle type — not to mention the types of sensing and communication technologies used to measure roadway information. Every differentiating factor introduces an exponentially larger set of control problems. There are thousands of control-problem variations and hundreds, if not thousands, of studies and papers dedicated to each problem. Wu refers to the sheer number of variations as the curse of variety — and it is hindering innovation.

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      “To prove that a new control strategy can be safely deployed on our streets can take years. As time lags, we lose opportunities to improve safety and equity while mitigating environmental impacts. Accelerating this process has huge potential,” says Wu.  

      Which is why she and her group in the MIT Laboratory for Information and Decision Systems are devising machine learning-based methods to solve not just a single control problem or a single optimization problem, but families of control and optimization problems at scale. “In our case, we’re examining emerging transportation problems that people have spent decades trying to solve with classical approaches. It seems to me that we need a different approach.”

      Optimizing intersections

      Currently, Wu’s largest research endeavor is called Project Greenwave. There are many sectors that directly contribute to climate change, but transportation is responsible for the largest share of greenhouse gas emissions — 29 percent, of which 81 percent is due to land transportation. And while much of the conversation around mitigating environmental impacts related to mobility is focused on electric vehicles (EVs), electrification has its drawbacks. EV fleet turnover is time-consuming (“on the order of decades,” says Wu), and limited global access to the technology presents a significant barrier to widespread adoption.

      Wu’s research, on the other hand, addresses traffic control problems by leveraging deep reinforcement learning. Specifically, she is looking at traffic intersections — and for good reason. In the United States alone, there are more than 300,000 signalized intersections where vehicles must stop or slow down before re-accelerating. And every re-acceleration burns fossil fuels and contributes to greenhouse gas emissions.

      Highlighting the magnitude of the issue, Wu says, “We have done preliminary analysis indicating that up to 15 percent of land transportation CO2 is wasted through energy spent idling and re-accelerating at intersections.”

      To date, she and her group have modeled 30,000 different intersections across 10 major metropolitan areas in the United States. That is 30,000 different configurations, roadway topologies (e.g., grade of road or elevation), different weather conditions, and variations in travel demand and fuel mix. Each intersection and its corresponding scenarios represents a unique multi-agent control problem.

      Wu and her team are devising techniques that can solve not just one, but a whole family of problems comprised of tens of thousands of scenarios. Put simply, the idea is to coordinate the timing of vehicles so they arrive at intersections when traffic lights are green, thereby eliminating the start, stop, re-accelerate conundrum. Along the way, they are building an ecosystem of tools, datasets, and methods to enable roadway interventions and impact assessments of strategies to significantly reduce carbon-intense urban driving.

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      Their collaborator on the project is the Utah Department of Transportation, which Wu says has played an essential role, in part by sharing data and practical knowledge that she and her group otherwise would not have been able to access publicly.

      “I appreciate industry and public sector collaborations,” says Wu. “When it comes to important societal problems, one really needs grounding with practitioners. One needs to be able to hear the perspectives in the field. My interactions with practitioners expand my horizons and help ground my research. You never know when you’ll hear the perspective that is the key to the solution, or perhaps the key to understanding the problem.”

      Finding the best routes

      In a similar vein, she and her research group are tackling large coordination problems. For example, vehicle routing. “Every day, delivery trucks route more than a hundred thousand packages for the city of Boston alone,” says Wu. Accomplishing the task requires, among other things, figuring out which trucks to use, which packages to deliver, and the order in which to deliver them as efficiently as possible. If and when the trucks are electrified, they will need to be charged, adding another wrinkle to the process and further complicating route optimization.

      The vehicle routing problem, and therefore the scope of Wu’s work, extends beyond truck routing for package delivery. Ride-hailing cars may need to pick up objects as well as drop them off; and what if delivery is done by bicycle or drone? In partnership with Amazon, for example, Wu and her team addressed routing and path planning for hundreds of robots (up to 800) in their warehouses.

      Every variation requires custom heuristics that are expensive and time-consuming to develop. Again, this is really a family of problems — each one complicated, time-consuming, and currently unsolved by classical techniques — and they are all variations of a central routing problem. The curse of variety meets operations and logistics.

      By combining classical approaches with modern deep-learning methods, Wu is looking for a way to automatically identify heuristics that can effectively solve all of these vehicle routing problems. So far, her approach has proved successful.

      “We’ve contributed hybrid learning approaches that take existing solution methods for small problems and incorporate them into our learning framework to scale and accelerate that existing solver for large problems. And we’re able to do this in a way that can automatically identify heuristics for specialized variations of the vehicle routing problem.” The next step, says Wu, is applying a similar approach to multi-agent robotics problems in automated warehouses.

      Wu and her group are making big strides, in part due to their dedication to use-inspired basic research. Rather than applying known methods or science to a problem, they develop new methods, new science, to address problems. The methods she and her team employ are necessitated by societal problems with practical implications. The inspiration for the approach? None other than Louis Pasteur, who described his research style in a now-famous article titled “Pasteur’s Quadrant.” Anthrax was decimating the sheep population, and Pasteur wanted to better understand why and what could be done about it. The tools of the time could not solve the problem, so he invented a new field, microbiology, not out of curiosity but out of necessity. More

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      in Energy

      MIT engineers create an energy-storing supercapacitor from ancient materials

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      Two of humanity’s most ubiquitous historical materials, cement and carbon black (which resembles very fine charcoal), may form the basis for a novel, low-cost energy storage system, according to a new study. The technology could facilitate the use of renewable energy sources such as solar, wind, and tidal power by allowing energy networks to remain stable despite fluctuations in renewable energy supply.

      The two materials, the researchers found, can be combined with water to make a supercapacitor — an alternative to batteries — that could provide storage of electrical energy. As an example, the MIT researchers who developed the system say that their supercapacitor could eventually be incorporated into the concrete foundation of a house, where it could store a full day’s worth of energy while adding little (or no) to the cost of the foundation and still providing the needed structural strength. The researchers also envision a concrete roadway that could provide contactless recharging for electric cars as they travel over that road.

      The simple but innovative technology is described this week in the journal PNAS, in a paper by MIT professors Franz-Josef Ulm, Admir Masic, and Yang-Shao Horn, and four others at MIT and at the Wyss Institute for Biologically Inspired Engineering.

      Capacitors are in principle very simple devices, consisting of two electrically conductive plates immersed in an electrolyte and separated by a membrane. When a voltage is applied across the capacitor, positively charged ions from the electrolyte accumulate on the negatively charged plate, while the positively charged plate accumulates negatively charged ions. Since the membrane in between the plates blocks charged ions from migrating across, this separation of charges creates an electric field between the plates, and the capacitor becomes charged. The two plates can maintain this pair of charges for a long time and then deliver them very quickly when needed. Supercapacitors are simply capacitors that can store exceptionally large charges.

      The amount of power a capacitor can store depends on the total surface area of its conductive plates. The key to the new supercapacitors developed by this team comes from a method of producing a cement-based material with an extremely high internal surface area due to a dense, interconnected network of conductive material within its bulk volume. The researchers achieved this by introducing carbon black — which is highly conductive — into a concrete mixture along with cement powder and water, and letting it cure. The water naturally forms a branching network of openings within the structure as it reacts with cement, and the carbon migrates into these spaces to make wire-like structures within the hardened cement. These structures have a fractal-like structure, with larger branches sprouting smaller branches, and those sprouting even smaller branchlets, and so on, ending up with an extremely large surface area within the confines of a relatively small volume. The material is then soaked in a standard electrolyte material, such as potassium chloride, a kind of salt, which provides the charged particles that accumulate on the carbon structures. Two electrodes made of this material, separated by a thin space or an insulating layer, form a very powerful supercapacitor, the researchers found.

      The two plates of the capacitor function just like the two poles of a rechargeable battery of equivalent voltage: When connected to a source of electricity, as with a battery, energy gets stored in the plates, and then when connected to a load, the electrical current flows back out to provide power.

      “The material is fascinating,” Masic says, “because you have the most-used manmade material in the world, cement, that is combined with carbon black, that is a well-known historical material — the Dead Sea Scrolls were written with it. You have these at least two-millennia-old materials that when you combine them in a specific manner you come up with a conductive nanocomposite, and that’s when things get really interesting.”

      As the mixture sets and cures, he says, “The water is systematically consumed through cement hydration reactions, and this hydration fundamentally affects nanoparticles of carbon because they are hydrophobic (water repelling).” As the mixture evolves, “the carbon black is self-assembling into a connected conductive wire,” he says. The process is easily reproducible, with materials that are inexpensive and readily available anywhere in the world. And the amount of carbon needed is very small — as little as 3 percent by volume of the mix — to achieve a percolated carbon network, Masic says.

      Supercapacitors made of this material have great potential to aid in the world’s transition to renewable energy, Ulm says. The principal sources of emissions-free energy, wind, solar, and tidal power, all produce their output at variable times that often do not correspond to the peaks in electricity usage, so ways of storing that power are essential. “There is a huge need for big energy storage,” he says, and existing batteries are too expensive and mostly rely on materials such as lithium, whose supply is limited, so cheaper alternatives are badly needed. “That’s where our technology is extremely promising, because cement is ubiquitous,” Ulm says.

      The team calculated that a block of nanocarbon-black-doped concrete that is 45 cubic meters (or yards) in size — equivalent to a cube about 3.5 meters across — would have enough capacity to store about 10 kilowatt-hours of energy, which is considered the average daily electricity usage for a household. Since the concrete would retain its strength, a house with a foundation made of this material could store a day’s worth of energy produced by solar panels or windmills and allow it to be used whenever it’s needed. And, supercapacitors can be charged and discharged much more rapidly than batteries.

      After a series of tests used to determine the most effective ratios of cement, carbon black, and water, the team demonstrated the process by making small supercapacitors, about the size of some button-cell batteries, about 1 centimeter across and 1 millimeter thick, that could each be charged to 1 volt, comparable to a 1-volt battery. They then connected three of these to demonstrate their ability to light up a 3-volt light-emitting diode (LED). Having proved the principle, they now plan to build a series of larger versions, starting with ones about the size of a typical 12-volt car battery, then working up to a 45-cubic-meter version to demonstrate its ability to store a house-worth of power.

      There is a tradeoff between the storage capacity of the material and its structural strength, they found. By adding more carbon black, the resulting supercapacitor can store more energy, but the concrete is slightly weaker, and this could be useful for applications where the concrete is not playing a structural role or where the full strength-potential of concrete is not required. For applications such as a foundation, or structural elements of the base of a wind turbine, the “sweet spot” is around 10 percent carbon black in the mix, they found.

      Another potential application for carbon-cement supercapacitors is for building concrete roadways that could store energy produced by solar panels alongside the road and then deliver that energy to electric vehicles traveling along the road using the same kind of technology used for wirelessly rechargeable phones. A related type of car-recharging system is already being developed by companies in Germany and the Netherlands, but using standard batteries for storage.

      Initial uses of the technology might be for isolated homes or buildings or shelters far from grid power, which could be powered by solar panels attached to the cement supercapacitors, the researchers say.

      Ulm says that the system is very scalable, as the energy-storage capacity is a direct function of the volume of the electrodes. “You can go from 1-millimeter-thick electrodes to 1-meter-thick electrodes, and by doing so basically you can scale the energy storage capacity from lighting an LED for a few seconds, to powering a whole house,” he says.

      Depending on the properties desired for a given application, the system could be tuned by adjusting the mixture. For a vehicle-charging road, very fast charging and discharging rates would be needed, while for powering a home “you have the whole day to charge it up,” so slower-charging material could be used, Ulm says.

      “So, it’s really a multifunctional material,” he adds. Besides its ability to store energy in the form of supercapacitors, the same kind of concrete mixture can be used as a heating system, by simply applying electricity to the carbon-laced concrete.

      Ulm sees this as “a new way of looking toward the future of concrete as part of the energy transition.”

      The research team also included postdocs Nicolas Chanut and Damian Stefaniuk at MIT’s Department of Civil and Environmental Engineering, James Weaver at the Wyss Institute, and Yunguang Zhu in MIT’s Department of Mechanical Engineering. The work was supported by the MIT Concrete Sustainability Hub, with sponsorship by the Concrete Advancement Foundation. More

    • 138 Shares129 Views

      in Energy

      3 Questions: What’s it like winning the MIT $100K Entrepreneurship Competition?

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      Solar power plays a major role in nearly every roadmap for global decarbonization. But solar panels are large, heavy, and expensive, which limits their deployment. But what if solar panels looked more like a yoga mat?

      Such a technology could be transported in a roll, carried to the top of a building, and rolled out across the roof in a matter of minutes, slashing installation costs and dramatically expanding the places where rooftop solar makes sense.

      That was the vision laid out by the MIT spinout Active Surfaces as part of the winning pitch at this year’s MIT $100K Entrepreneurship Competition, which took place May 15. The company is leveraging materials science and manufacturing innovations from labs across MIT to make ultra-thin, lightweight, and durable solar a reality.

      The $100K is one of MIT’s most visible entrepreneurship competitions, and past winners say the prize money is only part of the benefit that winning brings to a burgeoning new company. MIT News sat down with Active Surface founders Shiv Bhakta, a graduate student in MIT’s Leaders for Global Operations dual-degree program within the MIT Sloan School of Management and Department of Civil and Environmental Engineering, and Richard Swartwout SM ’18 PhD ’21, an electrical engineering and computer science graduate and former Research Laboratory of Electronics postdoc and MIT.nano innovation fellow, to learn what the last couple of months have been like since they won.

      Q: What is Active Surfaces’ solution, and what is its potential?

      Bhakta: We’re commercializing an ultrathin film, flexible solar technology. Solar is one of the most broadly distributed resources in the world, but access is limited today. It’s heavy — it weighs 50 to 60 pounds a panel — it requires large teams to move around, and the form factor can only be deployed in specific environments.

      Our approach is to develop a solar technology for the built environment. In a nutshell, we can create flexible solar panels that are as thin as paper, just as efficient as traditional panels, and at unprecedented cost floors, all while being applied to any surface. Same area, same power. That’s our motto.

      When I came to MIT, my north star was to dive deeper in my climate journey and help make the world a better, greener place. Now, as we build Active Surfaces, I’m excited to see that dream taking shape. The prospect of transforming any surface into an energy source, thereby expanding solar accessibility globally, holds the promise of significantly reducing CO2 emissions at a gigaton scale. That’s what gets me out of bed in the morning.

      Swartwout: Solar and a lot of other renewables tend to be pretty land-inefficient. Solar 1.0 is using low hanging fruit: cheap land next to easy interconnects and new buildings designed to handle the weight of current panels. But as we ramp up solar, those things will run out. We need to utilize spaces and assets better. That’s what I think solar 2.0 will be: urban PV deployments, solar that’s closer to demand, and integrated into the built environment. These next-generation use cases aren’t just a racking system in the middle of nowhere.

      We’re going after commercial roofs, which would cover most [building] energy demand. Something like 80-90 percent of building electricity demands in the space can be met by rooftop solar.

      The goal is to do the manufacturing in-house. We use roll-to-roll manufacturing, so we can buy tons of equipment off the shelf, but most roll-to-roll manufacturing is made for things like labeling and tape, and not a semiconductor, so our plan is to be the core of semiconductor roll-to-roll manufacturing. There’s never been roll-to-roll semiconductor manufacturing before.

      Q: What have the last few months been like since you won the $100K competition?

      Bhakta: After winning the $100K, we’ve gotten a lot of inbound contact from MIT alumni. I think that’s my favorite part about the MIT community — people stay connected. They’ve been congratulating us, asking to chat, looking to partner, deploy, and invest.

      We’ve also gotten contacted by previous $100K competition winners and other startups that have spun out of MIT that are a year or two or three ahead of us in terms of development. There are a lot of startup scaling challenges that other startup founders are best equipped to answer, and it’s been huge to get guidance from them.

      We’ve also gotten into top accelerators like Cleantech Open, Venture For Climatetech, and ACCEL at Greentown Labs. We also onboarded two rockstar MIT Sloan interns for the summer. Now we’re getting to the product-development phase, building relationships with potential pilot partners, and scaling up the area of our technology.      

      Swartwout: Winning the $100K competition was a great point of validation for the company, because the judges themselves are well known in the venture capital community as well as people who have been in the startup ecosystem for a long time, so that has really propelled us forward. Ideally, we’ll be getting more MIT alumni to join us to fulfill this mission.

      Q: What are your plans for the next year or so?

      Swartwout: We’re planning on leveraging open-access facilities like those at MIT.nano and the University of Massachusetts Amherst. We’re pretty focused now on scaling size. Out of the lab, [the technology] is a 4-inch by 4-inch solar module, and the goal is to get up to something that’s relevant for the industry to offset electricity for building owners and generate electricity for the grid at a reasonable cost.

      Bhakta: In the next year, through those open-access facilities, the goal is to go from 100-millimeter width to 300-millimeter width and a very long length using a roll-to-roll manufacturing process. That means getting through the engineering challenges of scaling technology and fine tuning the performance.

      When we’re ready to deliver a pilotable product, it’s my job to have customers lined up ready to demonstrate this works on their buildings, sign longer term contracts to get early revenue, and have the support we need to demonstrate this at scale. That’s the goal. More

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      in Environment

      Helping the transportation sector adapt to a changing world

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      After graduating from college, Nick Caros took a job as an engineer with a construction company, helping to manage the building of a new highway bridge right near where he grew up outside of Vancouver, British Columbia.  

      “I had a lot of friends that would use that new bridge to get to work,” Caros recalls. “They’d say, ‘You saved me like 20 minutes!’ That’s when I first realized that transportation could be a huge benefit to people’s lives.”

      Now a PhD candidate in the Urban Mobility Lab and the lead researcher for the MIT Transit Research Consortium, Caros works with seven transit agencies across the country to understand how workers’ transportation needs have changed as companies have adopted remote work policies.

      “Another cool thing about working on transportation is that everybody, even if they don’t engage with it on an academic level, has an opinion or wants to talk about it,” says Caros. “As soon as I mention I’ve worked with the T, they have something they want to talk about.”

      Caros is drawn to projects with social impact beyond saving his friends a few minutes during their commutes. He sees public transportation as a crucial component in combating climate change and is passionate about identifying and lowering the psychological barriers that prevent people around the world from taking advantage of their local transit systems.

      “The more I’ve learned about public transportation, the more I’ve come to realize it will play an essential part in decarbonizing urban transportation,” says Caros. “I want to continue working on these kinds of issues, like how we can make transportation more sustainable or promoting public transportation in places where it doesn’t exist or can be improved.”

      Caros says he doesn’t have a “transportation origin story,” like some of his peers who grew up in urban centers with robust public transit systems. As a child growing up in the Vancouver suburbs, he always enjoyed the outdoors, which were as close as his backyard. He chose to study engineering as an undergraduate at the University of British Columbia, fascinated by the hydroelectric dams that supply Vancouver with most of its power. But after two projects with the construction company, the second of which took him to Maryland to work on a fossil fuel project, he decided he needed a change.

      Not quite sure what he wanted to do next, Caros sought out the shortest master’s program he could find that interested him. That ended up being an 18-month master’s program in transportation planning and engineering at New York University. Initially intending to pursue the course-based program, Caros was soon offered the chance to be a research assistant in NYU’s Behavioral Urban Informatics, Logistics, and Transport Laboratory with Professor Joseph Chow. There, he worked to model an experimental transportation system of modular self-driving cars that could link and unlink with each other while in motion.

      “It was this really futuristic stuff,” says Caros. “It turned out to be a really cool project to work on because it’s kind of rare to have a blank-slate problem to try and solve. A lot of transportation engineering problems have largely been solved. We know how to make efficient and sustainable transportation systems; it’s just finding the political support and encouraging behavioral change that remains a challenge.”

      At NYU, Caros fell in love with research and the field of transportation. Later, he was drawn to MIT by its interdisciplinary PhD program that spans both urban studies and planning and civil engineering and the opportunity to work with Professor Jinhua Zhao.

      His research focuses on identifying “third places,” locations where some people go if their job gives them the flexibility to work remotely. Previously, transportation needs revolved around office spaces, typically located in city centers. With more people working from home, the first assumption is that transportation needs would decrease. But that’s not what Caros has found.

      “One major finding from our research is that people have changed where they’re going when they go to work,” says Caros. “A lot of people are working from home, but some are also working in other places, like coffee shops or co-working spaces. And these third places are not evenly distributed in Boston.”

      Identifying the concentration of these third places and what locations would benefit from them is the core of Caros’ dissertation. He’s building an algorithm that identifies ideal locations to build more shared workplaces based on both economic and social factors. Caros seeks to answer how you can minimize travel time across the board while leaving room for the spontaneous social interactions that drive a city’s productivity. His research is sponsored by seven of the largest transit agencies in the United States, who are members of the MIT Transit Research Consortium. Rather than a single agency sponsoring a single specific project, funding is pooled to tackle projects that address general topics that can apply to multiple cities.

      These kinds of problems require a multidisciplinary approach that appeals to Caros. Even when diving into the technical details of a solution, he always keeps the bigger picture in mind. He is certain that changing people’s views of public transportation will be crucial in the fight against climate change.

      “A lot of it is not necessarily engineering, but understanding what the motivations of people are,” says Caros. “Transportation is a leading sector for carbon emissions in the U.S., and so figuring out what makes people tick and how you can get them to ride public transit more, for example, would help to reduce the overall carbon cost.”

      Following the completion of his degree, Caros will join the Organization for Economic Cooperation and Development. He already spent six months at its Paris headquarters as an intern during a leave from MIT, something his lab encourages all of its students to do. Last fall, he worked on drafting policy guidelines for new mobility services such as vehicle-share scooters, and addressing transportation equity issues in Ghana. Plus, living in Paris gave him the opportunity to practice his French. Growing up in Canada, he attended a French immersion school, and his internship offered his first opportunity to use the language outside of an academic context.

      Looking forward, Caros hopes to keep tackling projects that promote sustainable public transportation. There is an urgency in getting ahead of the curve, especially in cities experiencing rapid growth.

      “You kind of get locked in,” says Caros. “It becomes much harder to build sustainable transportation systems after the fact. But it’s really just a geometry problem. Trains and buses are a way more efficient way to move people using the same amount of space as private cars.” More

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      in Environment

      Andrea Lo ’21 draws on ecological lessons for life, work, and education

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      Growing up in Los Angeles about 10 minutes away from the Ballona Wetlands, Andrea Lo ’21 has long been interested in ecology. She witnessed, in real-time, the effects of urbanization and the impacts that development had on the wetlands. 

      “In hindsight, it really helped shape my need for a career — and a life — where I can help improve my community and the environment,” she says.

      Lo, who majored in biology at MIT, says a recurring theme in her life has been the pursuit of balance, valuing both extracurricular and curricular activities. She always felt an equal pull toward STEM and the humanities, toward wet lab work and field work, and toward doing research and helping her community. 

      “One of the most important things I learned in 7.30[J] (Fundamentals of Ecology) was that there are always going to be trade-offs. That’s just the way of life,” she says. “The biology major at MIT is really flexible. I got a lot of room to explore what I was interested in and get a good balance overall, with humanities classes along with technical classes.” 

      Lo was drawn to MIT because of the focus on hands-on work — but many of the activities Lo was hoping to do, both extracurricular and curricular, were cut short because of the pandemic, including her lab-based Undergraduate Research Opportunities Program (UROP) project. 

      Instead, she pursued a UROP with MIT Sea Grant, working on a project in partnership with Northeastern University and the Charles River Conservancy with funding support from the MIT Community Service fund as part of STEAM Saturday.  

      She was involved in creating Floating Wetland kits, an educational activity directed at students in grades 4 to 6 to help students understand ecological concepts,the challenges the Charles River faces due to urbanization, and how floating wetlands improve the ecosystem. 

      “Our hope was to educate future generations of local students in Cambridge in order for them to understand the ecology surrounding where they live,” she says. 

      In recent years, many bodies of water in Massachusetts have become unusable during the warmer months due to the process of eutrophication: stormwater runoff picks up everything — from fertilizer and silt to animal excrement — and deposits it at the lowest point, which is often a body of water. This leads to an excess of nutrients in the body of water and, when combined with warm temperatures, can lead to harmful algal blooms, making the water sludgy, bright green, and dangerously toxic. 

      The wetland kits Lo worked with were mini ecosystems, replicating a full-sized floating wetland. One such floating wetland can be seen from the Longfellow Bridge at one end of MIT’s campus — the Charles River floating wetland is a patch of grass attached to a buoy like a boat, which is often visited by birds and inhabited by much smaller critters that cannot be seen from the shore.  

      The Charles River floating wetland has a variety of flora, but the kits Lo helped present use only wheat grass because it is easy to grow and has long, dangling roots that could penetrate the watery medium below. A water tray beneath the grass — the Charles river of the mini ecosystem — contains spirulina powder for replicating algae growth and daphnia, which are small, planktonic crustaceans that help keep freshwater clean and usable. 

      “This work was really fulfilling, but it’s also really important, because environmental sustainability relies on future generations to carry on the work that past generations have been doing,” she says. “MIT’s motto is ‘mens et manus’ — education for practical application, and applying theoretical knowledge to what we do in our daily lives. I think this project really helped reinforce that.” 

      Since 2021, Lo has been working in Denmark in a position she learned about through the MIT-Denmark program. 

      She chose Denmark because of its reputation for environmental and sustainability issues and because she didn’t know much about it except for it being one of the happiest countries in the world, often thought of synonymously with the word “hygge,” which has no direct translation but encapsulates coziness and comfort from the small joys in life. 

      “At MIT, we have a very strong work-hard, play-hard culture. I think we can learn a lot from the work-life balance that Denmark has a reputation for,” she says. “I really wanted to take the opportunity in between graduation and whatever came after to explore beyond my bubble. For me, it was important to step back, out of my comfort zone, step into a different environment — and just live.”

      Currently, her personal project is comparing the conditions of two lagoons on the island of Fyn in Denmark. Both are naturally occurring, but in different states of environmental health. 

      She’s been doing a mix of field work and lab work. She collects sediment and fauna samples using a steel corer, or “butter stick” in her lab’s slang. In the same way that one can use a metal tube-shaped tool to remove the core of an apple, she punches the steel corer into the ground, removing a plug of sample. She then sifts the sample through 1 millimeter mesh, preserves the filtered sample in formalin, and takes everything back to the lab. 

      Once there, she looks through the sample to find macrofauna — mollusks, barnacles, and polychaetes, a bristly-looking segmented worm, for example. Collected over time, sediment characteristics like organic matter content, sediment grain size, and the size and abundance of macrofauna, can reveal trends that can help determine the health of the ecosystem. 

      Lo doesn’t have any concrete results yet, but her data could help researchers project the recovery of a lagoon that was rehabilitated using a technique called managed realignment, where water is allowed to reclaim areas where it was once found. She says she’s glad she gets a mix of field work and lab work, even on Denmark’s stormiest days. 

      “Sometimes there are really cold days where it’s windy and I wish I was in the lab, but, at the same time, it’s nice to have a balance where I can be outside and really be hands-on with my work,” she says.  

      Reflecting her dual interests in the technical and the innovative, she will be back in the Greater Boston area in the fall, pursuing a master of science in innovation and management and an MS in civil and environmental engineering at the Tufts Gordon Institute.

      “So much has happened and changed due to the pandemic that it’s easy to dwell on what could’ve been, but I tell myself to be optimistic and take the positive aspects that have come out of the circumstances,” Lo says. “My opportunities with the Sea Grant, MISTI, and Tufts definitely wouldn’t have happened if the pandemic hadn’t happened.” More