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      in Environment

      Q&A: More-sustainable concrete with machine learning

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      As a building material, concrete withstands the test of time. Its use dates back to early civilizations, and today it is the most popular composite choice in the world. However, it’s not without its faults. Production of its key ingredient, cement, contributes 8-9 percent of the global anthropogenic CO2 emissions and 2-3 percent of energy consumption, which is only projected to increase in the coming years. With aging United States infrastructure, the federal government recently passed a milestone bill to revitalize and upgrade it, along with a push to reduce greenhouse gas emissions where possible, putting concrete in the crosshairs for modernization, too.

      Elsa Olivetti, the Esther and Harold E. Edgerton Associate Professor in the MIT Department of Materials Science and Engineering, and Jie Chen, MIT-IBM Watson AI Lab research scientist and manager, think artificial intelligence can help meet this need by designing and formulating new, more sustainable concrete mixtures, with lower costs and carbon dioxide emissions, while improving material performance and reusing manufacturing byproducts in the material itself. Olivetti’s research improves environmental and economic sustainability of materials, and Chen develops and optimizes machine learning and computational techniques, which he can apply to materials reformulation. Olivetti and Chen, along with their collaborators, have recently teamed up for an MIT-IBM Watson AI Lab project to make concrete more sustainable for the benefit of society, the climate, and the economy.

      Q: What applications does concrete have, and what properties make it a preferred building material?

      Olivetti: Concrete is the dominant building material globally with an annual consumption of 30 billion metric tons. That is over 20 times the next most produced material, steel, and the scale of its use leads to considerable environmental impact, approximately 5-8 percent of global greenhouse gas (GHG) emissions. It can be made locally, has a broad range of structural applications, and is cost-effective. Concrete is a mixture of fine and coarse aggregate, water, cement binder (the glue), and other additives.

      Q: Why isn’t it sustainable, and what research problems are you trying to tackle with this project?

      Olivetti: The community is working on several ways to reduce the impact of this material, including alternative fuels use for heating the cement mixture, increasing energy and materials efficiency and carbon sequestration at production facilities, but one important opportunity is to develop an alternative to the cement binder.

      While cement is 10 percent of the concrete mass, it accounts for 80 percent of the GHG footprint. This impact is derived from the fuel burned to heat and run the chemical reaction required in manufacturing, but also the chemical reaction itself releases CO2 from the calcination of limestone. Therefore, partially replacing the input ingredients to cement (traditionally ordinary Portland cement or OPC) with alternative materials from waste and byproducts can reduce the GHG footprint. But use of these alternatives is not inherently more sustainable because wastes might have to travel long distances, which adds to fuel emissions and cost, or might require pretreatment processes. The optimal way to make use of these alternate materials will be situation-dependent. But because of the vast scale, we also need solutions that account for the huge volumes of concrete needed. This project is trying to develop novel concrete mixtures that will decrease the GHG impact of the cement and concrete, moving away from the trial-and-error processes towards those that are more predictive.

      Chen: If we want to fight climate change and make our environment better, are there alternative ingredients or a reformulation we could use so that less greenhouse gas is emitted? We hope that through this project using machine learning we’ll be able to find a good answer.

      Q: Why is this problem important to address now, at this point in history?

      Olivetti: There is urgent need to address greenhouse gas emissions as aggressively as possible, and the road to doing so isn’t necessarily straightforward for all areas of industry. For transportation and electricity generation, there are paths that have been identified to decarbonize those sectors. We need to move much more aggressively to achieve those in the time needed; further, the technological approaches to achieve that are more clear. However, for tough-to-decarbonize sectors, such as industrial materials production, the pathways to decarbonization are not as mapped out.

      Q: How are you planning to address this problem to produce better concrete?

      Olivetti: The goal is to predict mixtures that will both meet performance criteria, such as strength and durability, with those that also balance economic and environmental impact. A key to this is to use industrial wastes in blended cements and concretes. To do this, we need to understand the glass and mineral reactivity of constituent materials. This reactivity not only determines the limit of the possible use in cement systems but also controls concrete processing, and the development of strength and pore structure, which ultimately control concrete durability and life-cycle CO2 emissions.

      Chen: We investigate using waste materials to replace part of the cement component. This is something that we’ve hypothesized would be more sustainable and economic — actually waste materials are common, and they cost less. Because of the reduction in the use of cement, the final concrete product would be responsible for much less carbon dioxide production. Figuring out the right concrete mixture proportion that makes endurable concretes while achieving other goals is a very challenging problem. Machine learning is giving us an opportunity to explore the advancement of predictive modeling, uncertainty quantification, and optimization to solve the issue. What we are doing is exploring options using deep learning as well as multi-objective optimization techniques to find an answer. These efforts are now more feasible to carry out, and they will produce results with reliability estimates that we need to understand what makes a good concrete.

      Q: What kinds of AI and computational techniques are you employing for this?

      Olivetti: We use AI techniques to collect data on individual concrete ingredients, mix proportions, and concrete performance from the literature through natural language processing. We also add data obtained from industry and/or high throughput atomistic modeling and experiments to optimize the design of concrete mixtures. Then we use this information to develop insight into the reactivity of possible waste and byproduct materials as alternatives to cement materials for low-CO2 concrete. By incorporating generic information on concrete ingredients, the resulting concrete performance predictors are expected to be more reliable and transformative than existing AI models.

      Chen: The final objective is to figure out what constituents, and how much of each, to put into the recipe for producing the concrete that optimizes the various factors: strength, cost, environmental impact, performance, etc. For each of the objectives, we need certain models: We need a model to predict the performance of the concrete (like, how long does it last and how much weight does it sustain?), a model to estimate the cost, and a model to estimate how much carbon dioxide is generated. We will need to build these models by using data from literature, from industry, and from lab experiments.

      We are exploring Gaussian process models to predict the concrete strength, going forward into days and weeks. This model can give us an uncertainty estimate of the prediction as well. Such a model needs specification of parameters, for which we will use another model to calculate. At the same time, we also explore neural network models because we can inject domain knowledge from human experience into them. Some models are as simple as multi-layer perceptions, while some are more complex, like graph neural networks. The goal here is that we want to have a model that is not only accurate but also robust — the input data is noisy, and the model must embrace the noise, so that its prediction is still accurate and reliable for the multi-objective optimization.

      Once we have built models that we are confident with, we will inject their predictions and uncertainty estimates into the optimization of multiple objectives, under constraints and under uncertainties.

      Q: How do you balance cost-benefit trade-offs?

      Chen: The multiple objectives we consider are not necessarily consistent, and sometimes they are at odds with each other. The goal is to identify scenarios where the values for our objectives cannot be further pushed simultaneously without compromising one or a few. For example, if you want to further reduce the cost, you probably have to suffer the performance or suffer the environmental impact. Eventually, we will give the results to policymakers and they will look into the results and weigh the options. For example, they may be able to tolerate a slightly higher cost under a significant reduction in greenhouse gas. Alternatively, if the cost varies little but the concrete performance changes drastically, say, doubles or triples, then this is definitely a favorable outcome.

      Q: What kinds of challenges do you face in this work?

      Chen: The data we get either from industry or from literature are very noisy; the concrete measurements can vary a lot, depending on where and when they are taken. There are also substantial missing data when we integrate them from different sources, so, we need to spend a lot of effort to organize and make the data usable for building and training machine learning models. We also explore imputation techniques that substitute missing features, as well as models that tolerate missing features, in our predictive modeling and uncertainty estimate.

      Q: What do you hope to achieve through this work?

      Chen: In the end, we are suggesting either one or a few concrete recipes, or a continuum of recipes, to manufacturers and policymakers. We hope that this will provide invaluable information for both the construction industry and for the effort of protecting our beloved Earth.

      Olivetti: We’d like to develop a robust way to design cements that make use of waste materials to lower their CO2 footprint. Nobody is trying to make waste, so we can’t rely on one stream as a feedstock if we want this to be massively scalable. We have to be flexible and robust to shift with feedstocks changes, and for that we need improved understanding. Our approach to develop local, dynamic, and flexible alternatives is to learn what makes these wastes reactive, so we know how to optimize their use and do so as broadly as possible. We do that through predictive model development through software we have developed in my group to automatically extract data from literature on over 5 million texts and patents on various topics. We link this to the creative capabilities of our IBM collaborators to design methods that predict the final impact of new cements. If we are successful, we can lower the emissions of this ubiquitous material and play our part in achieving carbon emissions mitigation goals.

      Other researchers involved with this project include Stefanie Jegelka, the X-Window Consortium Career Development Associate Professor in the MIT Department of Electrical Engineering and Computer Science; Richard Goodwin, IBM principal researcher; Soumya Ghosh, MIT-IBM Watson AI Lab research staff member; and Kristen Severson, former research staff member. Collaborators included Nghia Hoang, former research staff member with MIT-IBM Watson AI Lab and IBM Research; and Jeremy Gregory, research scientist in the MIT Department of Civil and Environmental Engineering and executive director of the MIT Concrete Sustainability Hub.

      This research is supported by the MIT-IBM Watson AI Lab. More

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      in Energy

      “Vigilant inclusion” central to combating climate change

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      “To turbocharge work on saving the planet, we need effective, innovative, localized solutions, and diverse perspectives and experience at the table,” said U.S. Secretary of Energy Jennifer M. Granholm, the keynote speaker at the 10th annual U.S. Clean Energy Education and Empowerment (C3E) Women in Clean Energy Symposium and Awards.

      This event, convened virtually over Nov. 3-4 and engaging more than 1,000 participants, was devoted to the themes of justice and equity in clean energy. In panels and presentations, speakers hammered home the idea that the benefits of a zero-carbon future must be shared equitably, especially among groups historically neglected or marginalized. To ensure this outcome, the speakers concluded, these same groups must help drive the clean-energy transition, and women, who stand to bear enormous burdens as the world warms, should be central to the effort. This means “practicing vigilant inclusion,” said Granholm.

      The C3E symposium, which is dedicated to celebrating the leadership of women in the field of clean energy and inspiring the next generation of women leaders, featured professionals from government, industry, research, and other sectors. Some of them spoke from experience, and from the heart, on issues of environmental justice.

      “I grew up in a trailer park in northern Utah, where it was so cold at night a sheet of ice formed on the inside of the door,” said Melanie Santiago-Mosier, the deputy director of the Clean Energy Group and Clean Energy States Alliance. Santiago-Mosier, who won a 2018 C3E award for advocacy, has devoted her career “to bringing the benefits of clean energy to families like mine, and to preventing mistakes of the past that result in a deeply unjust energy system.”

      Tracey A. LeBeau, a member of the Cheyenne River Sioux Tribe who grew up in South Dakota, described the flooding of her community’s land to create a hydroelectric dam, forcing the dislocation of many people. Today, as administrator and CEO of the Western Area Power Administration, LeBeau manages distribution of hydropower across 15 states, and has built an organization in which the needs of disadvantaged communities are top of mind. “I stay true to my indigenous point of view,” she said.

      The C3E Symposium was launched in 2012 to increase gender diversity in the energy sector and provide awards to outstanding women in the field. It is part of the C3E Initiative, a collaboration between the U.S. Department of Energy (DOE), the MIT Energy Initiative (MITEI), Texas A&M Energy Institute, and Stanford Precourt Institute for Energy, which hosted the event this year.

      Connecting global rich and poor

      As the COP26 climate summit unfolded in Glasgow, highlighting the sharp divide between rich and poor nations, C3E panelists pursued a related agenda. One panel focused on paths for collaboration between industrialized nations and nations with developing economies to build a sustainable, carbon-neutral global economy.

      Radhika Thakkar, the vice president of corporate affairs at solar home energy provider Greenlight Planet and a 2019 C3E international award winner, believes that small partnerships with women at the community level can lead to large impacts. When her company introduced solar lamp home systems to Rwanda, “Women abandoned selling bananas to sell our lamps, making enough money to purchase land, cows, even putting their families through school,” she said.

      Sudeshna Banerjee, the practice manager for Europe and Central Asia and the energy and extractives global practice at the World Bank, talked about impacts of a bank-supported electrification program in Nairobi slums where gang warfare kept girls confined at home. “Once the lights came on, girls felt more empowered to go around in dark hours,” she said. “This is what development is: creating opportunities for young women to do something with their lives, giving them educational opportunities and creating instances for them to generate income.”

      In another session, panelists focused on ways to enable disadvantaged communities in the United States to take full advantage of clean energy opportunities.

      Amy Glasmeier, a professor of economic geography and regional planning at MIT, believes remote, rural communities require broadband and other information channels in order to chart their own clean-energy journeys. “We must provide access to more than energy, so people can educate themselves and imagine how the energy transition can work for them.”

      Santiago-Mosier described the absence of rooftop solar in underprivileged neighborhoods of the nation’s cities and towns as the result of a kind of clean-energy redlining. “Clean energy and the solar industry are falling into 400-year-old traps of systemic racism,” she said. “This is no accident: senior executives in solar are white and male.” The answer is “making sure that providers and companies are elevating people of color and women in industries,” otherwise “solar is leaving potential growth on the table.”

      Data for equitable outcomes

      Jessica Granderson, the director of building technology at the White House Council on Environmental Quality and the 2015 C3E research award winner, is measuring and remediating greenhouse gas emissions from the nation’s hundred-million-plus homes and commercial structures. In a panel exploring data-driven solutions for advancing equitable energy outcomes, Granderson described using new building performance standards that improve the energy efficiency and material performance of construction in a way that does not burden building owners with modest resources. “We are emphasizing engagements at the community level, bringing in a local workforce, and addressing the needs of local programs, in a way that hasn’t necessarily been present in the past,” she said.

      To facilitate her studies on how people in these communities use and experience public transportation systems, Tierra Bills, an assistant professor in civil and environmental engineering at Wayne State University, is developing a community-based approach for collecting data. “Not everyone who is eager to contribute to a study can participate in an online survey and upload data, so we need to find ways of overcoming these barriers,” she said.

      Corporate efforts to advance social and environmental justice turn on community engagement as well. Paula Gold-Williams, a C3E ambassador and the president and CEO of CPS Energy, with 1 million customers in San Antonio, Texas, described a weatherization campaign to better insulate homes that involved “looking for as many places to go as possible in parts of town where people wouldn’t normally raise their hands.”

      Carla Peterman, the executive vice president for corporate affairs and chief of sustainability at Pacific Gas & Electric, and the 2015 C3E government award winner, was deliberating about raising rates some years ago. “My ‘aha’ moment was in a community workshop where I realized that a $5 increase is too much,” she said. “It may be the cost of a latte, but these folks aren’t buying lattes, and it’s a choice between electricity and food or shelter.”

      A call to arms

      Humanity cannot win the all-out race to achieve a zero-carbon future without a vast new cohort of participants, symposium speakers agreed. A number of the 2021 C3E award winners who have committed their careers to clean energy invoked the moral imperative of the moment and issued a call to arms.

      “Seven-hundred-and-fifty million people around the world live without reliable energy, and 70 percent of schools lack power,” said Rhonda Jordan-Antoine PhD ’12, a senior energy specialist at the World Bank who received this year’s international award. By laboring to bring smart grids, battery technologies, and regional integration to even the most remote communities, she said, we open up opportunities for education and jobs. “Energy access is not just about energy, but development,” said Antoine, “and I hope you are encouraged to advance clean energy efforts around the globe.”

      Faith Corneille, who won the government award, works in the U.S. Department of State’s Bureau of Energy Resources. “We need innovators and scientists to design solutions; energy efficiency experts and engineers to build; lawyers to review, and bankers to invest, and insurance agents to protect against risk; and we need problem-solvers to thread these together,” she said. “Whatever your path, there’s a role for you: energy and climate intersect with whatever you do.”

      “We know the cause of climate change and how to reverse it, but to make that happen we need passionate and brilliant minds, all pulling in the same direction,” said Megan Nutting, the executive vice president of government and regulatory affairs at Sunnova Energy Corporation, and winner of the business award. “The clean-energy transition needs women,” she said. “If you are not working in clean energy, then why not?” More

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      in Environment

      3 Questions: Tolga Durak on building a safety culture at MIT

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      Environment, Health, and Safety Managing Director Tolga Durak heads a team working to build a strong safety culture at the Institute and to implement systems that lead to successful lab and makerspace operations. EHS is also pursuing new opportunities in the areas of safe and sustainable labs and applied makerspace research. 

      Durak holds a BS in mechanical engineering, a MS in industrial and systems engineering, and a PhD in building construction/environmental design and planning. He has over 20 years of experience in engineering and EHS in higher education, having served in such roles as authority having jurisdiction, responsible official, fire marshal, risk manager, radiation safety officer, laser safety officer, safety engineer, project manager, and emergency manager for government agencies, as well as universities with extensive health-care and research facilities.

      Q: What “words of wisdom” regarding lab/shop health and safety would you like to share with the research community? 

      A: EHS staff always strive to help maintain the safety and well-being of the MIT community. When it comes to lab/shop safety or any areas with hazards, first and foremost, we encourage wearing the appropriate personal protective equipment (PPE) when handling potentially hazardous materials. While PPE needs depend on the hazards and the space, common PPE includes safety glasses, lab coats, gloves, clothes that cover your skin, and closed-toe shoes. Shorts and open-toe shoes have no place in the lab/shop setting when hazardous materials are stored or used. Accidents will and do happen. The severity of injuries due to accidental exposures can be minimized when researchers are wearing PPE. Remember, there is only one you!   

      Overall, be aware of your surroundings, be knowledgeable about the hazards of the materials and equipment you are using, and be prepared for the unexpected. Ask yourself, “What’s the worst thing that can happen during this experiment or procedure?” Prepare by doing a thorough risk assessment, ask others who may be knowledgeable for their ideas and help, and standardize procedures where possible. Be prepared to respond appropriately when an emergency arises. 

      Safety in our classrooms, labs, and makerspaces is paramount and requires a collaborative effort. 

      Q: What are the established programs within EHS that students and researchers should be aware of, and what opportunities and challenges do you face trying to advance a healthy safety culture at MIT? 

      A: The EHS program staff in Biosafety, Industrial Hygiene, Environmental Management, Occupational and Construction Safety, and Radiation Protection are ready to assist with risk assessments, chemical safety, physical hazards, hazard-specific training, materials management, and hazardous waste disposal and reuse/recycling. Locally, each department, laboratory, and center has an EHS coordinator, as well as an assigned EHS team, to assist in the implementation of required EHS programs. Each lab/shop also has a designated EHS representative — someone who has local knowledge of your lab/shop and can help you with safety requirements specific to your work area.  

      One of the biggest challenges we face is that due to the decentralized nature of the Institute, no one size fits all when it comes to implementing successful safety practices. We also view this as an opportunity to enhance our safety culture. A strong safety culture is reflected at MIT when all lab and makerspace members are willing to look out for each other, challenge the status quo when necessary, and do the right thing even when no one is looking. In labs/shops with a strong safety culture, faculty and researchers discuss safety topics at group meetings, group members remind each other to wear the appropriate PPE (lab coats, safety glasses, etc.), more experienced team members mentor the newcomers, and riskier operations are reviewed and assessed to make them as safe as possible.  

      Q: Can you describe the new Safe and Sustainable Laboratories (S2L) efforts and the makerspace operational research programs envisioned for the future? 

      A: The MIT EHS Office has a plan for renewing its dedication to sustainability and climate action. We are dedicated to doing our part to promote a research environment that assures the highest level of health and safety but also strives to reduce energy, water, and waste through educating and supporting faculty, students, and researchers. With the goal of integrating sustainability across the lab sector of campus and bridging that with the Institute’s climate action goals, EHS has partnered with the MIT Office of Sustainability, Department of Facilities, vice president for finance, and vice president for campus services and stewardship to relaunch the “green” labs sustainability efforts under a new Safe and Sustainable Labs program.

      Part of that plan is to implement a Sustainable Labs Certification program. The process is designed to be as easy as possible for the lab groups. We are starting with simple actions like promoting the use of equipment timers in certain locations to conserve energy, fume hood/ventilation management, preventative maintenance for ultra-low-temperature freezers, increasing recycling, and helping labs update their central chemical inventory system, which can help forecast MIT’s potential waste streams. 

      EHS has also partnered with Project Manus to build a test-bed lab to study potential health and environmental exposures present in makerspaces as a result of specialized equipment and processes with our new Applied Makerspace Research Initiative.   More

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      in Environment

      Scientists and musicians tackle climate change together

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      Audiences may travel long distances to see their favorite musical acts in concert or to attend large music festivals, which can add to their personal carbon footprint of emissions that are steadily warming the planet. But these same audiences, and the performers they follow, are often quite aware of the dangers of climate change and eager to contribute to ways of curbing those emissions.

      How should the industry reconcile these two perspectives, and how should it harness the enormous influence that musicians have on their fans to help promote action on climate change?

      That was the focus of a wide-ranging discussion on Monday hosted by MIT’s Environmental Solutions Initiative, titled “Artists and scientists together on climate solutions.” The event, which was held live at the Media Lab’s Bartos Theater and streamed online, featured John Fernandez, director of ESI; Dava Newman, director of the Media Lab; Tony McGuinness, a musician with the group Above and Beyond; and Anna Johnson, the sustainability and environment officer at Involved Group, an organization dedicated to embedding sustainability in business operations in the arts and culture fields.

      Fernandez pointed out in opening the discussion that when it comes to influencing people’s attitudes and behavior, changes tend to come about not just through information from a particular field, but rather from a whole culture. “We started thinking about how we might work with artists, how to have scientists and engineers, inventors, and designers working with artists on the challenges that we really need to face,” he said.

      Dealing with the climate change issue, he said, “is not about 2050 or 2100. This is about 2030. This is about this decade. This is about the next two or three years, really shifting that curve” to lowering the world’s greenhouse gas emissions. “It’s not going to be done just with science and engineering,” he added. “It’s got to be done with artists and business and everyone else. It’s not only ‘all of the above’ solutions, it’s ‘all of the above’ people, coming together to solve this problem.”

      Newman, who is also a professor in MIT’s Department of Aeronautics and Astronautics and has served as a NASA deputy administrator, said that while scientists and engineers can produce vast amounts of useful data that clearly demonstrate the dramatic changes the Earth’s climate is undergoing, communicating that information effectively is often a challenge for these specialists. “That data is just the data, but that doesn’t change the hearts and minds,” she said.

      “As scientists, having the data from our satellites, looking down, but also flying airplanes into the atmosphere, … we have the sensors, and then what can we do with it all? … How do we change human behavior? That’s the part I don’t know how to do,” Newman said. “I can have the technology, I can get precision measurements, I can study it, but really at the end of the day, we have to change human behavior, and that is so hard.”

      And that’s where the world of art and music can play a part, she said. “The best way that I know how to do it is with artistic experiences. You can have one moving experience and when you wake up tomorrow, maybe you’re going to do something a little different.” To help generate the compassion and empathy needed to affect behavior positively, she said, “that’s where we turn to the storytellers. We turn to the visionaries.”

      McGuinness, whose electronic music trio has performed for millions of people around the world, said that his own awareness of the urgency of the climate issue came from his passion for scuba diving, and the dramatic changes he has seen over the last two decades. In diving at a coral reef off Palau in the South Pacific, he returned to what had been a lush, brightly colored ecosystem, and found that “immediately when you put your face under the water, you’re looking at the surface of the moon. It was a horrible shock to see this.”

      After this and other similar diving experiences, he said, “I just came away shocked and stunned,” and realizing the kinds of underwater experiences he had enjoyed would no longer exist for his children. After reading more on the subject of global warming,  “that really sort of tipped me over the edge. And I was like, this is probably the most important thing for living beings now. And that’s sort of where I’ve remained ever since.”

      While his group Above and Beyond has performed one song specifically related to global warming, he doesn’t expect that to be the most impactful way of using their influence. Rather, they’re trying to lead by example, he said, by paying more attention to everything from the supply chains of the merchandise sold at concerts to the emissions generated by travel to the concerts. They’re also being selective about concert venues and making an effort to find performance spaces that are making a significant effort to curb their emissions.

      “If people start voting with their wallets,” McGuinness said, “and there are companies that are doing better than others and are doing the right thing, maybe it’ll catch on. I guess that’s what we can hope for.”

      Understanding these kinds of issues, involving supply chains, transportation, and facilities associated within the music industry, has been the focus of much of Johnson’s work, through the organization Involved Group, which has entered into a collaboration with MIT through the Environmental Solutions Initiative. “It’s these kinds of novel partnerships that have so much potential to catalyze the change that we need to see at an incredible pace,” she said. Already, her group has worked with MIT on mapping out where emissions occur throughout the various aspects of the music industry.

      At a recent music festival in London, she said, the group interviewed hundreds of participants, including audience members, band members, and the crew. “We explored people’s level of awareness of the issues around climate change and environmental degradation,” she said. “And what was really interesting was that there was clearly a lot of awareness of the issue across those different stakeholders, and what felt like a real, genuine level of concern and also of motivation, to want to deepen their understanding of what their contribution on a personal level really meant.”

      Working together across the boundaries of different disciplines and areas of expertise could be crucial to winning the battle against global warming, Newman said. “That’s usually how breakthroughs work,” she said. “If we’re really looking to have impact, it’s going to be from teams of people who are trained across the disciplines.” She pointed out that 90 percent of MIT students are also musicians: “It does go together!” she said. “I think going forward, we have to create new academia, new opportunities that are truly multidisciplinary.” More

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      in Energy

      An energy-storage solution that flows like soft-serve ice cream

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      Batteries made from an electrically conductive mixture the consistency of molasses could help solve a critical piece of the decarbonization puzzle. An interdisciplinary team from MIT has found that an electrochemical technology called a semisolid flow battery can be a cost-competitive form of energy storage and backup for variable renewable energy (VRE) sources such as wind and solar. The group’s research is described in a paper published in Joule.

      “The transition to clean energy requires energy storage systems of different durations for when the sun isn’t shining and the wind isn’t blowing,” says Emre Gençer, a research scientist with the MIT Energy Initiative (MITEI) and a member of the team. “Our work demonstrates that a semisolid flow battery could be a lifesaving as well as economical option when these VRE sources can’t generate power for a day or longer — in the case of natural disasters, for instance.”

      The rechargeable zinc-manganese dioxide (Zn-MnO2) battery the researchers created beat out other long-duration energy storage contenders. “We performed a comprehensive, bottom-up analysis to understand how the battery’s composition affects performance and cost, looking at all the trade-offs,” says Thaneer Malai Narayanan SM ’18, PhD ’21. “We showed that our system can be cheaper than others, and can be scaled up.”

      Narayanan, who conducted this work at MIT as part of his doctorate in mechanical engineering, is the lead author of the paper. Additional authors include Gençer, Yunguang Zhu, a postdoc in the MIT Electrochemical Energy Lab; Gareth McKinley, the School of Engineering Professor of Teaching Innovation and professor of mechanical engineering at MIT; and Yang Shao-Horn, the JR East Professor of Engineering, a professor of mechanical engineering and of materials science and engineering, and a member of the Research Laboratory of Electronics (RLE), who directs the MIT Electrochemical Energy Lab.

      Going with the flow

      In 2016, Narayanan began his graduate studies, joining the Electrochemical Energy Lab, a hotbed of research and exploration of solutions to mitigate climate change, which is centered on innovative battery chemistry and decarbonizing fuels and chemicals. One exciting opportunity for the lab: developing low- and no-carbon backup energy systems suitable for grid-scale needs when VRE generation flags.                                                  

      While the lab cast a wide net, investigating energy conversion and storage using solid oxide fuel cells, lithium-ion batteries, and metal-air batteries, among others, Narayanan took a particular interest in flow batteries. In these systems, two different chemical (electrolyte) solutions with either negative or positive ions are pumped from separate tanks, meeting across a membrane (called the stack). Here, the ion streams react, converting electrical energy to chemical energy — in effect, charging the battery. When there is demand for this stored energy, the solution gets pumped back to the stack to convert chemical energy into electrical energy again.

      The duration of time that flow batteries can discharge, releasing the stored electricity, is determined by the volume of positively and negatively charged electrolyte solutions streaming through the stack. In theory, as long as these solutions keep flowing, reacting, and converting the chemical energy to electrical energy, the battery systems can provide electricity.

      “For backup lasting more than a day, the architecture of flow batteries suggests they can be a cheap option,” says Narayanan. “You recharge the solution in the tanks from sun and wind power sources.” This renders the entire system carbon free.

      But while the promise of flow battery technologies has beckoned for at least a decade, the uneven performance and expense of materials required for these battery systems has slowed their implementation. So, Narayanan set out on an ambitious journey: to design and build a flow battery that could back up VRE systems for a day or more, storing and discharging energy with the same or greater efficiency than backup rivals; and to determine, through rigorous cost analysis, whether such a system could prove economically viable as a long-duration energy option.

      Multidisciplinary collaborators

      To attack this multipronged challenge, Narayanan’s project brought together, in his words, “three giants, scientists all well-known in their fields”:  Shao-Horn, who specializes in chemical physics and electrochemical science, and design of materials; Gençer, who creates detailed economic models of emergent energy systems at MITEI; and McKinley, an expert in rheology, the physics of flow. These three also served as his thesis advisors.

      “I was excited to work in such an interdisciplinary team, which offered a unique opportunity to create a novel battery architecture by designing charge transfer and ion transport within flowable semi-solid electrodes, and to guide battery engineering using techno-economics of such flowable batteries,” says Shao-Horn.

      While other flow battery systems in contention, such as the vanadium redox flow battery, offer the storage capacity and energy density to back up megawatt and larger power systems, they depend on expensive chemical ingredients that make them bad bets for long duration purposes. Narayanan was on the hunt for less-pricey chemical components that also feature rich energy potential.

      Through a series of bench experiments, the researchers came up with a novel electrode (electrical conductor) for the battery system: a mixture containing dispersed manganese dioxide (MnO2) particles, shot through with an electrically conductive additive, carbon black. This compound reacts with a conductive zinc solution or zinc plate at the stack, enabling efficient electrochemical energy conversion. The fluid properties of this battery are far removed from the watery solutions used by other flow batteries.

      “It’s a semisolid — a slurry,” says Narayanan. “Like thick, black paint, or perhaps a soft-serve ice cream,” suggests McKinley. The carbon black adds the pigment and the electric punch. To arrive at the optimal electrochemical mix, the researchers tweaked their formula many times.

      “These systems have to be able to flow under reasonable pressures, but also have a weak yield stress so that the active MnO2 particles don’t sink to the bottom of the flow tanks when the system isn’t being used, as well as not separate into a battery/oily clear fluid phase and a dense paste of carbon particles and MnO2,” says McKinley.

      This series of experiments informed the technoeconomic analysis. By “connecting the dots between composition, performance, and cost,” says Narayanan, he and Gençer were able to make system-level cost and efficiency calculations for the Zn-MnO2 battery.

      “Assessing the cost and performance of early technologies is very difficult, and this was an example of how to develop a standard method to help researchers at MIT and elsewhere,” says Gençer. “One message here is that when you include the cost analysis at the development stage of your experimental work, you get an important early understanding of your project’s cost implications.”

      In their final round of studies, Gençer and Narayanan compared the Zn-MnO2 battery to a set of equivalent electrochemical battery and hydrogen backup systems, looking at the capital costs of running them at durations of eight, 24, and 72 hours. Their findings surprised them: For battery discharges longer than a day, their semisolid flow battery beat out lithium-ion batteries and vanadium redox flow batteries. This was true even when factoring in the heavy expense of pumping the MnO2 slurry from tank to stack. “I was skeptical, and not expecting this battery would be competitive, but once I did the cost calculation, it was plausible,” says Gençer.

      But carbon-free battery backup is a very Goldilocks-like business: Different situations require different-duration solutions, whether an anticipated overnight loss of solar power, or a longer-term, climate-based disruption in the grid. “Lithium-ion is great for backup of eight hours and under, but the materials are too expensive for longer periods,” says Gençer. “Hydrogen is super expensive for very short durations, and good for very long durations, and we will need all of them.” This means it makes sense to continue working on the Zn-MnO2 system to see where it might fit in.

      “The next step is to take our battery system and build it up,” says Narayanan, who is working now as a battery engineer. “Our research also points the way to other chemistries that could be developed under the semi-solid flow battery platform, so we could be seeing this kind of technology used for energy storage in our lifetimes.”

      This research was supported by Eni S.p.A. through MITEI. Thaneer Malai Narayanan received an Eni-sponsored MIT Energy Fellowship during his work on the project. More

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      in Energy

      Energy hackers give a glimpse of the postpandemic future

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      After going virtual in 2020, the MIT EnergyHack was back on campus last weekend in a brand-new hybrid format that saw teams participate both in person and virtually from across the globe. While the hybrid format presented new challenges to the organizing team, it also allowed for one of the most diverse and inspiring iterations of the event to date.

      “Organizing a hybrid event was a challenging but important goal in 2021 as we slowly come out of the pandemic, but it was great to realize the benefits of the format this year,” says Kailin Graham, a graduate student in MIT’s Technology and Policy Program and one of the EnergyHack communications directors. “Not only were we able to get students back on campus and taking advantage of those important in-person interactions, but preserving a virtual avenue meant that we were still able to hear brilliant ideas from those around the world who might not have had the opportunity to contribute otherwise, and that’s what the EnergyHack is really about.”

      In fact, of the over 300 participants registered for the event, more than a third participated online, and two of the three grand prize winners participated entirely virtually. Teams of students at any degree level from any institution were welcome, and the event saw an incredible range of backgrounds and expertise, from undergraduates to MBAs, put their heads together to create innovative solutions.

      This year’s event was supported by a host of energy partners both in industry and within MIT. The MIT Energy and Climate Club worked with sponsoring organizations Smartflower, Chargepoint, Edison Energy, Line Vision, Chevron, Shell, and Sterlite Power to develop seven problem statements for hackers, with each judged by representatives form their respective organization. The challenges ranged from envisioning the future of electric vehicle fueling to quantifying the social and environmental benefits of renewable energy projects.

      Hackers had 36 hours to come up with a solution to one challenge, and teams then presented these solutions in a short pitch to a judging panel. Finalists from each challenge progressed to the final judging round to pitch against each other in pursuit of three grand prizes. Team COPrs came in third, receiving $1,000 for their solution to the Line Vision challenge; Crown Joules snagged second place and $1,500 for their approach to the Chargepoint problem; and Feel AMPowered took out first place and $2,000 for their innovative solution to the Smartflower challenge.

      In addition to a new format, this year’s EnergyHack also featured a new emphasis on climate change impacts and the energy transition. According to Arina Khotimsky, co-managing director of EnergyHack 2021, “Moving forward after this year’s rebranding of the MIT Energy and Climate Club, we were hoping to carry this aim to EnergyHack. It was incredibly exciting to have ChargePoint and SmartFlower leading as our Sustainability Circle-tier sponsors and bringing their impactful innovations to the conversations at EnergyHack 2021.”

      To the organizing team, whose members from sophomores to MBAs, this aspect of the event was especially important, and their hope was for the event to inspire a generation of young energy and climate leaders — a hope, according to them, that seems to have been fulfilled.

      “I was floored by the positive feedback we received from hackers, both in-person and virtual, about how much they enjoyed the hackathon,” says Graham. “It’s all thanks to our team of incredibly hardworking organizing directors who made EnergyHack 2021 what it was. It was incredibly rewarding seeing everyone’s impact on the event, and we are looking forward to seeing how it evolves in the future.”­­­ More

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      in Environment

      Energy hackers give a glimpse of a postpandemic future

      by

      After going virtual in 2020, the MIT EnergyHack was back on campus last weekend in a brand-new hybrid format that saw teams participate both in person and virtually from across the globe. While the hybrid format presented new challenges to the organizing team, it also allowed for one of the most diverse and inspiring iterations of the event to date.

      “Organizing a hybrid event was a challenging but important goal in 2021 as we slowly come out of the pandemic, but it was great to realize the benefits of the format this year,” says Kailin Graham, a graduate student in MIT’s Technology and Policy Program and one of the EnergyHack communications directors. “Not only were we able to get students back on campus and taking advantage of those important in-person interactions, but preserving a virtual avenue meant that we were still able to hear brilliant ideas from those around the world who might not have had the opportunity to contribute otherwise, and that’s what the EnergyHack is really about.”

      In fact, of the over 300 participants registered for the event, more than a third participated online, and two of the three grand prize winners participated entirely virtually. Teams of students at any degree level from any institution were welcome, and the event saw an incredible range of backgrounds and expertise, from undergraduates to MBAs, put their heads together to create innovative solutions.

      This year’s event was supported by a host of energy partners both in industry and within MIT. The MIT Energy and Climate Club worked with sponsoring organizations Smartflower, Chargepoint, Edison Energy, Line Vision, Chevron, Shell, and Sterlite Power to develop seven problem statements for hackers, with each judged by representatives form their respective organization. The challenges ranged from envisioning the future of electric vehicle fueling to quantifying the social and environmental benefits of renewable energy projects.

      Hackers had 36 hours to come up with a solution to one challenge, and teams then presented these solutions in a short pitch to a judging panel. Finalists from each challenge progressed to the final judging round to pitch against each other in pursuit of three grand prizes. Team COPrs came in third, receiving $1,000 for their solution to the Line Vision challenge; Crown Joules snagged second place and $1,500 for their approach to the Chargepoint problem; and Feel AMPowered took out first place and $2,000 for their innovative solution to the Smartflower challenge.

      In addition to a new format, this year’s EnergyHack also featured a new emphasis on climate change impacts and the energy transition. According to Arina Khotimsky, co-managing director of EnergyHack 2021, “Moving forward after this year’s rebranding of the MIT Energy and Climate Club, we were hoping to carry this aim to EnergyHack. It was incredibly exciting to have ChargePoint and SmartFlower leading as our Sustainability Circle-tier sponsors and bringing their impactful innovations to the conversations at EnergyHack 2021.”

      To the organizing team, whose members from sophomores to MBAs, this aspect of the event was especially important, and their hope was for the event to inspire a generation of young energy and climate leaders — a hope, according to them, that seems to have been fulfilled.

      “I was floored by the positive feedback we received from hackers, both in-person and virtual, about how much they enjoyed the hackathon,” says Graham. “It’s all thanks to our team of incredibly hardworking organizing directors who made EnergyHack 2021 what it was. It was incredibly rewarding seeing everyone’s impact on the event, and we are looking forward to seeing how it evolves in the future.”­­­ More

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      in Energy

      Timber or steel? Study helps builders reduce carbon footprint of truss structures

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      Buildings are a big contributor to global warming, not just in their ongoing operations but in the materials used in their construction. Truss structures — those crisscross arrays of diagonal struts used throughout modern construction, in everything from antenna towers to support beams for large buildings — are typically made of steel or wood or a combination of both. But little quantitative research has been done on how to pick the right materials to minimize these structures’ contribution global warming.

      The “embodied carbon” in a construction material includes the fuel used in the material’s production (for mining and smelting steel, for example, or for felling and processing trees) and in transporting the materials to a site. It also includes the equipment used for the construction itself.

      Now, researchers at MIT have done a detailed analysis and created a set of computational tools to enable architects and engineers to design truss structures in a way that can minimize their embodied carbon while maintaining all needed properties for a given building application. While in general wood produces a much lower carbon footprint, using steel in places where its properties can provide maximum benefit can provide an optimized result, they say.

      The analysis is described in a paper published today in the journal Engineering Structures, by graduate student Ernest Ching and MIT assistant professor of civil and environmental engineering Josephine Carstensen.

      “Construction is a huge greenhouse gas emitter that has kind of been flying under the radar for the past decades,” says Carstensen. But in recent years building designers “are starting to be more focused on how to not just reduce the operating energy associated with building use, but also the important carbon associated with the structure itself.” And that’s where this new analysis comes in.

      The two main options in reducing the carbon emissions associated with truss structures, she says, are substituting materials or changing the structure. However, there has been “surprisingly little work” on tools to help designers figure out emissions-minimizing strategies for a given situation, she says.

      The new system makes use of a technique called topology optimization, which allows for the input of basic parameters, such as the amount of load to be supported and the dimensions of the structure, and can be used to produce designs optimized for different characteristics, such as weight, cost, or, in this case, global warming impact.

      Wood performs very well under forces of compression, but not as well as steel when it comes to tension — that is, a tendency to pull the structure apart. Carstensen says that in general, wood is far better than steel in terms of embedded carbon, so “especially if you have a structure that doesn’t have any tension, then you should definitely only use timber” in order to minimize emissions. One tradeoff is that “the weight of the structure is going to be bigger than it would be with steel,” she says.

      The tools they developed, which were the basis for Ching’s master’s thesis, can be applied at different stages, either in the early planning phase of a structure, or later on in the final stages of a design.

      As an exercise, the team developed a proposal for reengineering several trusses using these optimization tools, and demonstrated that a significant savings in embodied greenhouse gas emissions could be achieved with no loss of performance. While they have shown improvements of at least 10 percent can be achieved, she says those estimates are “not exactly apples to apples” and likely savings could actually be two to three times that.

      “It’s about choosing materials more smartly,” she says, for the specifics of a given application. Often in existing buildings “you will have timber where there’s compression, and where that makes sense, and then it will have really skinny steel members, in tension, where that makes sense. And that’s also what we see in our design solutions that are suggested, but perhaps we can see it even more clearly.” The tools are not ready for commercial use though, she says, because they haven’t yet added a user interface.

      Carstensen sees a trend to increasing use of timber in large construction, which represents an important potential for reducing the world’s overall carbon emissions. “There’s a big interest in the construction industry in mass timber structures, and this speaks right into that area. So, the hope is that this would make inroads into the construction business and actually make a dent in that very large contribution to greenhouse gas emissions.” More