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      Cutting urban carbon emissions by retrofitting buildings

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      To support the worldwide struggle to reduce carbon emissions, many cities have made public pledges to cut their carbon emissions in half by 2030, and some have promised to be carbon neutral by 2050. Buildings can be responsible for more than half a municipality’s carbon emissions. Today, new buildings are typically designed in ways that minimize energy use and carbon emissions. So attention focuses on cleaning up existing buildings.

      A decade ago, leaders in some cities took the first step in that process: They quantified their problem. Based on data from their utilities on natural gas and electricity consumption and standard pollutant-emission rates, they calculated how much carbon came from their buildings. They then adopted policies to encourage retrofits, such as adding insulation, switching to double-glazed windows, or installing rooftop solar panels. But will those steps be enough to meet their pledges?

      “In nearly all cases, cities have no clear plan for how they’re going to reach their goal,” says Christoph Reinhart, a professor in the Department of Architecture and director of the Building Technology Program. “That’s where our work comes in. We aim to help them perform analyses so they can say, ‘If we, as a community, do A, B, and C to buildings of a certain type within our jurisdiction, then we are going to get there.’”

      To support those analyses, Reinhart and a team in the MIT Sustainable Design Lab (SDL) — PhD candidate Zachary M. Berzolla SM ’21; former doctoral student Yu Qian Ang PhD ’22, now a research collaborator at the SDL; and former postdoc Samuel Letellier-Duchesne, now a senior building performance analyst at the international building engineering and consulting firm Introba — launched a publicly accessible website providing a series of simulation tools and a process for using them to determine the impacts of planned steps on a specific building stock. Says Reinhart: “The takeaway can be a clear technology pathway — a combination of building upgrades, renewable energy deployments, and other measures that will enable a community to reach its carbon-reduction goals for their built environment.”

      Analyses performed in collaboration with policymakers from selected cities around the world yielded insights demonstrating that reaching current goals will require more effort than city representatives and — in a few cases — even the research team had anticipated.

      Exploring carbon-reduction pathways

      The researchers’ approach builds on a physics-based “building energy model,” or BEM, akin to those that architects use to design high-performance green buildings. In 2013, Reinhart and his team developed a method of extending that concept to analyze a cluster of buildings. Based on publicly available geographic information system (GIS) data, including each building’s type, footprint, and year of construction, the method defines the neighborhood — including trees, parks, and so on — and then, using meteorological data, how the buildings will interact, the airflows among them, and their energy use. The result is an “urban building energy model,” or UBEM, for a neighborhood or a whole city.

      The website developed by the MIT team enables neighborhoods and cities to develop their own UBEM and to use it to calculate their current building energy use and resulting carbon emissions, and then how those outcomes would change assuming different retrofit programs or other measures being implemented or considered. “The website — UBEM.io — provides step-by-step instructions and all the simulation tools that a team will need to perform an analysis,” says Reinhart.

      The website starts by describing three roles required to perform an analysis: a local sustainability champion who is familiar with the municipality’s carbon-reduction efforts; a GIS manager who has access to the municipality’s urban datasets and maintains a digital model of the built environment; and an energy modeler — typically a hired consultant — who has a background in green building consulting and individual building energy modeling.

      The team begins by defining “shallow” and “deep” building retrofit scenarios. To explain, Reinhart offers some examples: “‘Shallow’ refers to things that just happen, like when you replace your old, failing appliances with new, energy-efficient ones, or you install LED light bulbs and weatherstripping everywhere,” he says. “‘Deep’ adds to that list things you might do only every 20 years, such as ripping out walls and putting in insulation or replacing your gas furnace with an electric heat pump.”

      Once those scenarios are defined, the GIS manager uploads to UBEM.io a dataset of information about the city’s buildings, including their locations and attributes such as geometry, height, age, and use (e.g., commercial, retail, residential). The energy modeler then builds a UBEM to calculate the energy use and carbon emissions of the existing building stock. Once that baseline is established, the energy modeler can calculate how specific retrofit measures will change the outcomes.

      Workshop to test-drive the method

      Two years ago, the MIT team set up a three-day workshop to test the website with sample users. Participants included policymakers from eight cities and municipalities around the world: namely, Braga (Portugal), Cairo (Egypt), Dublin (Ireland), Florianopolis (Brazil), Kiel (Germany), Middlebury (Vermont, United States), Montreal (Canada), and Singapore. Taken together, the cities represent a wide range of climates, socioeconomic demographics, cultures, governing structures, and sizes.

      Working with the MIT team, the participants presented their goals, defined shallow- and deep-retrofit scenarios for their city, and selected a limited but representative area for analysis — an approach that would speed up analyses of different options while also generating results valid for the city as a whole.

      They then performed analyses to quantify the impacts of their retrofit scenarios. Finally, they learned how best to present their findings — a critical part of the exercise. “When you do this analysis and bring it back to the people, you can say, ‘This is our homework over the next 30 years. If we do this, we’re going to get there,’” says Reinhart. “That makes you part of the community, so it’s a joint goal.”

      Sample results

      After the close of the workshop, Reinhart and his team confirmed their findings for each city and then added one more factor to the analyses: the state of the city’s electric grid. Several cities in the study had pledged to make their grid carbon-neutral by 2050. Including the grid in the analysis was therefore critical: If a building becomes all-electric and purchases its electricity from a carbon-free grid, then that building will be carbon neutral — even with no on-site energy-saving retrofits.

      The final analysis for each city therefore calculated the total kilograms of carbon dioxide equivalent emitted per square meter of floor space assuming the following scenarios: the baseline; shallow retrofit only; shallow retrofit plus a clean electricity grid; deep retrofit only; deep retrofit plus rooftop photovoltaic solar panels; and deep retrofit plus a clean electricity grid. (Note that “clean electricity grid” is based on the area’s most ambitious decarbonization target for their power grid.)

      The following paragraphs provide highlights of the analyses for three of the eight cities. Included are the city’s setting, emission-reduction goals, current and proposed measures, and calculations of how implementation of those measures would affect their energy use and carbon emissions.

      Singapore

      Singapore is generally hot and humid, and its building energy use is largely in the form of electricity for cooling. The city is dominated by high-rise buildings, so there’s not much space for rooftop solar installations to generate the needed electricity. Therefore, plans for decarbonizing the current building stock must involve retrofits. The shallow-retrofit scenario focuses on installing energy-efficient lighting and appliances. To those steps, the deep-retrofit scenario adds adopting a district cooling system. Singapore’s stated goals are to cut the baseline carbon emissions by about a third by 2030 and to cut it in half by 2050.

      The analysis shows that, with just the shallow retrofits, Singapore won’t achieve its 2030 goal. But with the deep retrofits, it should come close. Notably, decarbonizing the electric grid would enable Singapore to meet and substantially exceed its 2050 target assuming either retrofit scenario.

      Dublin

      Dublin has a mild climate with relatively comfortable summers but cold, humid winters. As a result, the city’s energy use is dominated by fossil fuels, in particular, natural gas for space heating and domestic hot water. The city presented just one target — a 40 percent reduction by 2030.

      Dublin has many neighborhoods made up of Georgian row houses, and, at the time of the workshop, the city already had a program in place encouraging groups of owners to insulate their walls. The shallow-retrofit scenario therefore focuses on weatherization upgrades (adding weatherstripping to windows and doors, insulating crawlspaces, and so on). To that list, the deep-retrofit scenario adds insulating walls and installing upgraded windows. The participants didn’t include electric heat pumps, as the city was then assessing the feasibility of expanding the existing district heating system.

      Results of the analyses show that implementing the shallow-retrofit scenario won’t enable Dublin to meet its 2030 target. But the deep-retrofit scenario will. However, like Singapore, Dublin could make major gains by decarbonizing its electric grid. The analysis shows that a decarbonized grid — with or without the addition of rooftop solar panels where possible — could more than halve the carbon emissions that remain in the deep-retrofit scenario. Indeed, a decarbonized grid plus electrification of the heating system by incorporating heat pumps could enable Dublin to meet a future net-zero target.

      Middlebury

      Middlebury, Vermont, has warm, wet summers and frigid winters. Like Dublin, its energy demand is dominated by natural gas for heating. But unlike Dublin, it already has a largely decarbonized electric grid with a high penetration of renewables.

      For the analysis, the Middlebury team chose to focus on an aging residential neighborhood similar to many that surround the city core. The shallow-retrofit scenario calls for installing heat pumps for space heating, and the deep-retrofit scenario adds improvements in building envelopes (the façade, roof, and windows). The town’s targets are a 40 percent reduction from the baseline by 2030 and net-zero carbon by 2050.

      Results of the analyses showed that implementing the shallow-retrofit scenario won’t achieve the 2030 target. The deep-retrofit scenario would get the city to the 2030 target but not to the 2050 target. Indeed, even with the deep retrofits, fossil fuel use remains high. The explanation? While both retrofit scenarios call for installing heat pumps for space heating, the city would continue to use natural gas to heat its hot water.

      Lessons learned

      For several policymakers, seeing the results of their analyses was a wake-up call. They learned that the strategies they had planned might not be sufficient to meet their stated goals — an outcome that could prove publicly embarrassing for them in the future.

      Like the policymakers, the researchers learned from the experience. Reinhart notes three main takeaways.

      First, he and his team were surprised to find how much of a building’s energy use and carbon emissions can be traced to domestic hot water. With Middlebury, for example, even switching from natural gas to heat pumps for space heating didn’t yield the expected effect: On the bar graphs generated by their analyses, the gray bars indicating carbon from fossil fuel use remained. As Reinhart recalls, “I kept saying, ‘What’s all this gray?’” While the policymakers talked about using heat pumps, they were still going to use natural gas to heat their hot water. “It’s just stunning that hot water is such a big-ticket item. It’s huge,” says Reinhart.

      Second, the results demonstrate the importance of including the state of the local electric grid in this type of analysis. “Looking at the results, it’s clear that if we want to have a successful energy transition, the building sector and the electric grid sector both have to do their homework,” notes Reinhart. Moreover, in many cases, reaching carbon neutrality by 2050 would require not only a carbon-free grid but also all-electric buildings.

      Third, Reinhart was struck by how different the bar graphs presenting results for the eight cities look. “This really celebrates the uniqueness of different parts of the world,” he says. “The physics used in the analysis is the same everywhere, but differences in the climate, the building stock, construction practices, electric grids, and other factors make the consequences of making the same change vary widely.”

      In addition, says Reinhart, “there are sometimes deeply ingrained conflicts of interest and cultural norms, which is why you cannot just say everybody should do this and do this.” For instance, in one case, the city owned both the utility and the natural gas it burned. As a result, the policymakers didn’t consider putting in heat pumps because “the natural gas was a significant source of municipal income, and they didn’t want to give that up,” explains Reinhart.

      Finally, the analyses quantified two other important measures: energy use and “peak load,” which is the maximum electricity demanded from the grid over a specific time period. Reinhart says that energy use “is probably mostly a plausibility check. Does this make sense?” And peak load is important because the utilities need to keep a stable grid.

      Middlebury’s analysis provides an interesting look at how certain measures could influence peak electricity demand. There, the introduction of electric heat pumps for space heating more than doubles the peak demand from buildings, suggesting that substantial additional capacity would have to be added to the grid in that region. But when heat pumps are combined with other retrofitting measures, the peak demand drops to levels lower than the starting baseline.

      The aftermath: An update

      Reinhart stresses that the specific results from the workshop provide just a snapshot in time; that is, where the cities were at the time of the workshop. “This is not the fate of the city,” he says. “If we were to do the same exercise today, we’d no doubt see a change in thinking, and the outcomes would be different.”

      For example, heat pumps are now familiar technology and have demonstrated their ability to handle even bitterly cold climates. And in some regions, they’ve become economically attractive, as the war in Ukraine has made natural gas both scarce and expensive. Also, there’s now awareness of the need to deal with hot water production.

      Reinhart notes that performing the analyses at the workshop did have the intended impact: It brought about change. Two years after the project had ended, most of the cities reported that they had implemented new policy measures or had expanded their analysis across their entire building stock. “That’s exactly what we want,” comments Reinhart. “This is not an academic exercise. It’s meant to change what people focus on and what they do.”

      Designing policies with socioeconomics in mind

      Reinhart notes a key limitation of the UBEM.io approach: It looks only at technical feasibility. But will the building owners be willing and able to make the energy-saving retrofits? Data show that — even with today’s incentive programs and subsidies — current adoption rates are only about 1 percent. “That’s way too low to enable a city to achieve its emission-reduction goals in 30 years,” says Reinhart. “We need to take into account the socioeconomic realities of the residents to design policies that are both effective and equitable.”

      To that end, the MIT team extended their UBEM.io approach to create a socio-techno-economic analysis framework that can predict the rate of retrofit adoption throughout a city. Based on census data, the framework creates a UBEM that includes demographics for the specific types of buildings in a city. Accounting for the cost of making a specific retrofit plus financial benefits from policy incentives and future energy savings, the model determines the economic viability of the retrofit package for representative households.

      Sample analyses for two Boston neighborhoods suggest that high-income households are largely ineligible for need-based incentives or the incentives are insufficient to prompt action. Lower-income households are eligible and could benefit financially over time, but they don’t act, perhaps due to limited access to information, a lack of time or capital, or a variety of other reasons.

      Reinhart notes that their work thus far “is mainly looking at technical feasibility. Next steps are to better understand occupants’ willingness to pay, and then to determine what set of federal and local incentive programs will trigger households across the demographic spectrum to retrofit their apartments and houses, helping the worldwide effort to reduce carbon emissions.”

      This work was supported by Shell through the MIT Energy Initiative. Zachary Berzolla was supported by the U.S. National Science Foundation Graduate Research Fellowship. Samuel Letellier-Duchesne was supported by the postdoctoral fellowship of the Natural Sciences and Engineering Research Council of Canada.

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

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      Panel addresses technologies needed for a net-zero future

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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      Powering the future in Mongolia

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      Nestled within the Tuul River valley and embraced by the southern Khentii Mountain Range, Ulaanbaatar (UB), Mongolia’s largest city, presents itself as an arena where nature’s forces wage an unrelenting battle against human resilience. The capital city is an icy crucible, with bone-chilling winters that plummet temperatures to an astonishing -40 degrees Fahrenheit (-40 degrees Celsius). Mongolia, often hailed with the celestial moniker of “The Land of the Eternal Blue Sky,” paradoxically succumbs to a veil of pollution and energy struggles during the winter months, obscuring the true shade of the cherished vista.

      To understand the root of these issues, MIT students from classes 22.S094 (Climate and Sustainability Systems: Decarbonizing Ulaanbaatar at Scale) and 21A.S01 (Anthro-Engineering: Decarbonization at the Million-Person Scale) visited Mongolia to conduct on-site surveys, diving into the diverse tapestry of local life as they gleaned insight from various stakeholder groups. Setting foot on Mongolian soil on a crisp day in January, they wasted no time in shaking off the weariness of their arduous 17-hour flight, promptly embarking on a waiting bus. As they traversed the vast expanse of the countryside, their eyes were captivated by snow-laden terrain.

      That is, until a disconcerting sight unfolded — thick smog, akin to ethereal pillars, permeated the cityscape ahead. These imposing plumes emanated from the colossal smokestacks of Ulaanbaatar’s coal-fired power plants, steadfastly churning electricity and heat to fuel Mongolia’s central and district energy systems. Over 93 percent of the nation’s energy comes from coal-fired power plants, where the most considerable load is caused by household consumption. Nevertheless, with nearly half of Ulaanbaatar’s population disconnected from the central heating networks, one of Mongolia’s most significant sources of pollution comes from coal-burning stoves in the residential settlements known as the ger districts. Over the past three decades, since the democratic revolution in 1990, Mongolians have grappled with escalating concerns surrounding energy provision, accessibility, and sustainability.

      Engineers who think like anthropologists

      “We find ourselves compelled to venture on-site, engaging in direct conversations with the locals, and immersing ourselves in the fabric of daily life to uncover what we don’t know,” emphasized Michael Short, professor in MIT’s Department of Nuclear Science and Engineering and faculty lead of MIT’s NEET Climate and Sustainability Systems thread, shortly before heading to Mongolia.

      The Ulaanbaatar Project sprang from a multiyear collaboration between MIT and the National University of Mongolia (NUM). Shedding light on the matter, Professor Munkhbat Byambajav of the Department of Chemical and Biological Engineering at NUM underscored the paramount importance of mitigating environmental pollution at an economic scale to alleviate the heavy burden borne by the people.

      Class 22.S094 is offered through MIT’s New Engineering Education Transformation (NEET) program, which allows students with multidisciplinary interests to collaborate across departments within four different subject areas, or threads. In this capstone project, students consider ways to decarbonize a city like Ulaanbaatar, transitioning from burning coal briquettes to a more sustainable, energy-efficient solution, given several parameters and constraints set by the local context.

      One of the ideas students have recently explored is a thermal battery made with molten salt that can store enough energy to heat a ger for up to 12 hours with added insulation for cooling curve regulation. The Mongolian ger, meaning home, is a dome-like portable dwelling covered in felt and canvas, held together by ropes traditionally crafted of animal hair or wool. Over several semesters, students have been testing a version of their proposed idea on campus, working with a prototype that weighs around 35 pounds.

      Nathan Melenbrink, the lead instructor of NEET’s Climate and Sustainability Systems (CSS) thread, believes that the complexity of the Ulaanbaatar capstone project allows students to reject the one-way solution approach and instead consider challenges with a nonprescriptive mindset. The uniqueness of the CSS thread is that students are asked to build on the previous findings from the past cohort and iterate on their designs each year. This workflow has allowed the project to mature and advance in ways that may not be feasible within a semester schedule. When asked how the recent trip impacted the ongoing research back on campus, Melenbrink states, “In light of the recent trip to Mongolia, students are beginning to see the impact of cultural immersion and social awareness leveraging the technical scope and rigor of their work.”

      Course 21A.S01, taught by Professor Manduhai Buyandelger of the MIT Anthropology Section, proved instrumental in deepening students’ understanding of the intricate dynamics at play. She asks, “The prototype works in the lab, but does it work in real life once you factor in the challenges in the larger structures of delivery, production, and implementation in Mongolia?”

      This recognition of the social dimensions of engineering permeated the early stages of the UB project, engaging all participants, including students from MIT and NUM, professionals residing in Mongolia, and local nongovernmental organizations, fostering what Buyandelger aptly describes as “a collaboration on multiple scales: trans-disciplinary and transcontinental.” Lauren Bonilla, co-lecturer for the anthropology course, was crucial in devising the first onsite trip to Mongolia. Drawing upon her extensive ethnographic research in Mongolia that spans decades, Bonilla remarks, “To me, engineering is a highly social discipline.” She further stresses how anthro-engineering elevates the social dimensions of engineering by critically questioning the framing of problems and solutions, stating, “It draws on anthropological insights and methods, like ethnography, to bring a human face to the users of a technology and adds complexity and nuance to the social constraints that limit designs.”

      Making of khorkhog

      Amidst the frigid atmosphere, a traditional Mongolian ger stands in front of the Nuclear Science Laboratory at the National University of Mongolia, emitting warm steam from its roof. The faculty and students of NUM organize a welcoming event inside the ger, inviting everyone to partake in a khorkhog cookout. Earlier that week, a remark from the Mongolian energy representative stood out during one of the presentations: “We need powerful heat. Solar is not enough, and electricity is not enough. Mongolians need fire,” he had emphasized.

      Indeed, the culinary delight known as khorkhog demands the relentless embrace of scorching flames. The process involves a large metal jug, stones, fire, and lamb. With skillful precision, the volunteer chef places the fire-heated stones and large pieces of lamb into the cooking container, triggering a cascade of steam that fills the ger, accompanied by the sounds of sizzling and hissing. Everyone waits patiently as the cook carefully inspects the dish, keenly listening for signs of readiness. And when the time comes, a feast is shared among all, complemented by steam-cooked potatoes, freshly sliced onions, and vegetables. In this moment, the presence of fire symbolizes a profound connection with the heart of Mongolian culture, evoking a deep resonance among the gathered crowd as they partake in this cherished staple meal.

      The distance between two points

      Familiar faces form a grid on the computer screen as the standing meeting between the students in Massachusetts and Ulaanbaatar begins. Sharing the morning (evening in Mongolia) for updates has been a critical effort by both sides to stay engaged and make decisions together. NEET CSS students in Cambridge proceeded to share their latest findings.

      Lucy Nester, a nuclear science and engineering major, has been diligently working on developing a high-efficiency electrical heating solution for individual consumers. Her primary focus is leveraging the discounted electricity rates available in the ger districts and utilize existing infrastructure. Recognizing the importance of maximum flexibility in heating the brick, Nester emphasizes the “no one-size-fits-all” solution. She shares the results of her test trials, which involve both inductive and resistive heating methods, outlining the advantages and disadvantages of each approach. Despite her limited experience in electrical engineering and circuit building, Nester has impressively overcome the steep learning curve. She enthusiastically describes her UB trip as “one of the most remarkable experiences I’ve had during my time at MIT.”

      Darshdeep Grewal, a dedicated materials science and engineering major with a strong passion for data science and computation, has been diligently conducting research on convection heating using COMSOL Multiphysics. In his investigation, Grewal explores the correlation between air temperature and heating, investigates the impact of convecting air arrangement on the heating process, and examines the conditions that may contribute to overheating. Leveraging his expertise in computational workflows, Grewal presents an impressive collection of heatmap simulations derived from the extensive data accumulated by his team throughout the project. Recognizing the immense value of these simulations in modeling complex scenarios, he highlights the importance of running experiments concurrently with simulations to ensure accurate calibration of results, stating, “It’s important to stay rooted in reality.”

      Arina Khotimsky, another materials science and engineering major, has actively engaged in NEET’s Climate and Sustainability Systems thread since her sophomore year. Balancing the demands of her final semester at MIT and the upcoming review of 22.S094, Khotimsky reveals how she has seamlessly integrated her project involvement into her energy studies minor. Reflecting on her journey, she remarks, “Working on the Ulaanbaatar project has taught me the significance of taking local context into account while suggesting solutions as an engineer.” Khotimsky has been tirelessly iterating and refining the insulation box prototype, which holds the thermal battery and controls the rate at which the battery releases heat. In addition, the on-site observations have unveiled another design challenge — ensuring the insulation box functions as a secure and dependable means of transportation. 

      To “engineer” means to contrive through one’s deliberate use of skills. What confronted the UB Project team on site was not the limitations of skill or technology, but the real-world constraints often amiss in the early equation: the people and their everyday lives. With over 6,195 miles of distance between the two groups, it takes more than just dedication to make a collaboration blossom. That may be the desire for a positive impact. Moreover, it may be the goal of cultivating a healthier relationship with energy that spans a million-person scale. No matter where you are, there is no one solution to the complex story of energy. This progressive realization brings the two teams together every two weeks in virtual space, bridging the distance between the two points.  More

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      Tackling the MIT campus’s top energy consumers, building by building

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      When staff in MIT’s Department of Facilities would visualize energy use and carbon-associated emissions by campus buildings, Building 46 always stood out — attributed to its energy intensity, which accounted for 8 percent of MIT’s total campus energy use. This high energy draw was not surprising, as the building is home of the Brain and Cognitive Sciences Complex and a large amount of lab space, but it also made the building a perfect candidate for an energy performance audit to seek out potential energy saving opportunities.

      This audit revealed that several energy efficiency updates to the building mechanical systems infrastructure, including optimization of the room-by-room ventilation rates, could result in an estimated 35 percent reduction of energy use, which would in turn lower MIT’s total greenhouse gas emissions by an estimated 2 percent — driving toward the Institute’s 2026 goal of net-zero and 2050 goal of elimination of direct campus emissions.

      Building energy efficiency projects are not new for MIT. Since 2010, MIT has been engaged in a partnership agreement with utility company Eversource establishing the Efficiency Forward program, empowering MIT to invest in more than 300 energy conservation projects to date and lowering energy consumption on campus for a total calculated savings of approximately 70 million kilowatt hours and 4.2 million therms. But at 418,000 gross square feet, Building 46 is the first energy efficiency project of its size on the campus.

      “We’ve never tackled a whole building like this — it’s the first capital project that is technically an energy project,” explains Siobhan Carr, energy efficiency program manager, who was part of the team overseeing the energy audit and lab ventilation performance assessment in the building. “That gives you an idea of the magnitude and complexity of this.”

      The project started with the full building energy assessment and lab ventilation risk audit. “We had a team go through every corner of the building and look at every possible opportunity to save energy,” explains Jessica Parks, senior project manager for systems performance and turnover in campus construction. “One of the biggest issues we saw was that there’s a lot of dry lab spaces which are basically offices, but they’re all getting the same ventilation as if they were a high-intensity lab.” Higher ventilation and more frequent air exchange rates draw more energy. By optimizing for the required ventilation rates, there was an opportunity to save energy in nearly every space in the building.

      In addition to the optimized ventilation, the project team will convert fume hoods from constant volume to variable volume and install equipment to help the building systems run more efficiently. The team also identified opportunities to work with labs to implement programs such as fume hood hibernation and unoccupied setbacks for temperature and ventilation. As different spaces in the building have varying needs, the energy retrofit will touch all 1,254 spaces in the building — one by one — to implement the different energy measures to reach that estimated 35 percent reduction in energy use.

      Although time-consuming and complex, this room-by-room approach has a big benefit in that it has allowed research to continue in the space largely uninterrupted. With a few exceptions, the occupants of Building 46, which include the Department of Brain and Cognitive Sciences, The McGovern Institute for Brain Research, and The Picower Institute for Learning and Memory, have remained in place for the duration of the project. Partners in the MIT Environment, Health and Safety Office are instrumental to this balance of renovations and keeping the building operational during the optimization efforts and are one of several teams across MIT contributing to building efficiency efforts.

      The completion date of the building efficiency project is set for 2024, but Carr says that some of the impact of this ongoing work may soon be seen. “We should start to see savings as we move through the building, and we expect to fully realize all of our projected savings a year after completion,” she says, noting that the length of time is required for a year-over-year perspective to see the full reduction in energy use.

      The impact of the project goes far beyond the footprint of Building 46 as it offers insights and spurred actions for future projects — including buildings 76 and 68, the number two and three top energy users on campus. Both buildings recently underwent their own energy audits and lab ventilation performance assessments. The energy efficiency team is now crafting a plan for full-building approaches, much like Building 46. “To date, 46 has presented many learning opportunities, such as how to touch every space in a building while research continues, as well as how to overcome challenges encountered when working on existing systems,” explains Parks. “The good news is that we have developed solutions for those challenges and the teams have been proactively implementing those lessons in our other projects.”

      Communication has proven to be another key for these large projects where occupants see the work happening and often play a role in answering questions about their unique space. “People are really engaged, they ask questions about the work, and we ask them about the space they’re in every day,” says Parks. “The Building 46 occupants have been wonderful partners as we worked in all of their spaces, which is paving the way for a successful project.”

      The release of Fast Forward in 2021 has also made communications easier, notes Carr, who says the plan helps to frame these projects as part of the big picture — not just a construction interruption. “Fast Forward has brought a visibility into what we’re doing within [MIT] Facilities on these buildings,” she says. “It brings more eyes and ears, and people understand that these projects are happening throughout campus and not just in their own space — we’re all working to reduce energy and to reduce greenhouse gas across campus.”

      The Energy Efficiency team will continue to apply that big-picture approach as ongoing building efficiency projects on campus are assessed to reach toward a 10 to 15 percent reduction in energy use and corresponding emissions over the next several years. More

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      Pursuing a practical approach to research

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      Koroush Shirvan, the John Clark Hardwick Career Development Professor in the Department of Nuclear Science and Engineering (NSE), knows that the nuclear industry has traditionally been wary of innovations until they are shown to have proven utility. As a result, he has relentlessly focused on practical applications in his research, work that has netted him the 2022 Reactor Technology Award from the American Nuclear Society. “The award has usually recognized practical contributions to the field of reactor design and has not often gone to academia,” Shirvan says.

      One of these “practical contributions” is in the field of accident-tolerant fuels, a program launched by the U.S. Nuclear Regulatory Commission in the wake of the 2011 Fukushima Daiichi incident. The goal within this program, says Shirvan, is to develop new forms of nuclear fuels that can tolerate heat. His team, with students from over 16 countries, is working on numerous possibilities that range in composition and method of production.

      Another aspect of Shirvan’s research focuses on how radiation impacts heat transfer mechanisms in the reactor. The team found fuel corrosion to be the driving force. “[The research] informs how nuclear fuels perform in the reactor, from a practical point of view,” Shirvan says.

      Optimizing nuclear reactor design

      A summer internship when Shirvan was an undergraduate at the University of Florida at Gainesville seeded his drive to focus on practical applications in his studies. A nearby nuclear utility was losing millions because of crud accumulating on fuel rods. Over time, the company was solving the problem by using more fuel, before it had extracted all the life from earlier batches.

      Placement of fuel rods in nuclear reactors is a complex problem with many factors — the life of the fuel, location of hot spots — affecting outcomes. Nuclear reactors change their configuration of fuel rods every 18-24 months to optimize close to 15-20 constraints, leading to roughly 200-800 assemblies. The mind-boggling nature of the problem means that plants have to rely on experienced engineers.

      During his internship, Shirvan optimized the program used to place fuel rods in the reactor. He found that certain rods in assemblies were more prone to the crud deposits, and reworked their configurations, optimizing for these rods’ performance instead of adding assemblies.

      In recent years, Shirvan has applied a branch of artificial intelligence — reinforcement learning — to the configuration problem and created a software program used by the largest U.S. nuclear utility. “This program gives even a layperson the ability to reconfigure the fuels and the reactor without having expert knowledge,” Shirvan says.

      From advanced math to counting jelly beans

      Shirvan’s own expertise in nuclear science and engineering developed quite organically. He grew up in Tehran, Iran, and when he was 14 the family moved to Gainesville, where Shirvan’s aunt and family live. He remembers an awkward couple of years at the new high school where he was grouped in with newly arrived international students, and placed in entry-level classes. “I went from doing advanced mathematics in Iran to counting jelly beans,” he laughs.

      Shirvan applied to the University of Florida for his undergraduate studies since it made economic sense; the school gave full scholarships to Floridian students who received a certain minimum SAT score. Shirvan qualified. His uncle, who was a professor in the nuclear engineering department then, encouraged Shirvan to take classes in the department. Under his uncle’s mentorship, the courses Shirvan took, and his internship, cemented his love of the interdisciplinary approach that the field demanded.

      Having always known that he wanted to teach — he remembers finishing his math tests early in Tehran so he could earn the reward of being class monitor — Shirvan knew graduate school was next. His uncle encouraged him to apply to MIT and to the University of Michigan, home to reputable programs in the field. Shirvan chose MIT because “only at MIT was there a program on nuclear design. There were faculty dedicated to designing new reactors, looking at multiple disciplines, and putting all of that together.” He went on to pursue his master’s and doctoral studies at NSE under the supervision of Professor Mujid Kazimi, focusing on compact pressurized and boiling water reactor designs. When Kazimi passed away suddenly in 2015, Shirvan was a research scientist, and switched to tenure track to guide the professor’s team.

      Another project that Shirvan took in 2015: leadership of MIT’s course on nuclear reactor technology for utility executives. Offered only by the Institute, the program is an introduction to nuclear engineering and safety for personnel who might not have much background in the area. “It’s a great course because you get to see what the real problems are in the energy sector … like grid stability,” Shirvan says.

      A multipronged approach to savings

      Another very real problem nuclear utilities face is cost. Contrary to what one hears on the news, one of the biggest stumbling blocks to building new nuclear facilities in the United States is cost, which today can be up to three times that of renewables, Shirvan says. While many approaches such as advanced manufacturing have been tried, Shirvan believes that the solution to decrease expenditures lies in designing more compact reactors.

      His team has developed an open-source advanced nuclear cost tool and has focused on two different designs: a small water reactor using compact steam technology and a horizontal gas reactor. Compactness also means making fuels more efficient, as Shirvan’s work does, and in improving the heat exchange device. It’s all back to the basics and bringing “commercial viable arguments in with your research,” Shirvan explains.

      Shirvan is excited about the future of the U.S. nuclear industry, and that the 2022 Inflation Reduction Act grants the same subsidies to nuclear as it does for renewables. In this new level playing field, advanced nuclear still has a long way to go in terms of affordability, he admits. “It’s time to push forward with cost-effective design,” Shirvan says, “I look forward to supporting this by continuing to guide these efforts with research from my team.” More

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      A breakthrough on “loss and damage,” but also disappointment, at UN climate conference

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      As the 2022 United Nations climate change conference, known as COP27, stretched into its final hours on Saturday, Nov. 19, it was uncertain what kind of agreement might emerge from two weeks of intensive international negotiations.

      In the end, COP27 produced mixed results: on the one hand, a historic agreement for wealthy countries to compensate low-income countries for “loss and damage,” but on the other, limited progress on new plans for reducing the greenhouse gas emissions that are warming the planet.

      “We need to drastically reduce emissions now — and this is an issue this COP did not address,” said U.N. Secretary-General António Guterres in a statement at the conclusion of COP27. “A fund for loss and damage is essential — but it’s not an answer if the climate crisis washes a small island state off the map — or turns an entire African country to desert.”

      Throughout the two weeks of the conference, a delegation of MIT students, faculty, and staff was at the Sharm El-Sheikh International Convention Center to observe the negotiations, conduct and share research, participate in panel discussions, and forge new connections with researchers, policymakers, and advocates from around the world.

      Loss and damage

      A key issue coming in to COP27 (COP stands for “conference of the parties” to the U.N. Framework Convention on Climate Change, held for the 27th time) was loss and damage: a term used by the U.N. to refer to harms caused by climate change — either through acute catastrophes like extreme weather events or slower-moving impacts like sea level rise — to which communities and countries are unable to adapt. 

      Ultimately, a deal on loss and damage proved to be COP27’s most prominent accomplishment. Negotiators reached an eleventh-hour agreement to “establish new funding arrangements for assisting developing countries that are particularly vulnerable to the adverse effects of climate change.” 

      “Providing financial assistance to developing countries so they can better respond to climate-related loss and damage is not only a moral issue, but also a pragmatic one,” said Michael Mehling, deputy director of the MIT Center for Energy and Environmental Policy Research, who attended COP27 and participated in side events. “Future emissions growth will be squarely centered in the developing world, and offering support through different channels is key to building the trust needed for more robust global cooperation on mitigation.”

      Youssef Shaker, a graduate student in the MIT Technology and Policy Program and a research assistant with the MIT Energy Initiative, attended the second week of the conference, where he followed the negotiations over loss and damage closely. 

      “While the creation of a fund is certainly an achievement,” Shaker said, “significant questions remain to be answered, such as the size of the funding available as well as which countries receive access to it.” A loss-and-damage fund that is not adequately funded, Shaker noted, “would not be an impactful outcome.” 

      The agreement on loss and damage created a new committee, made up of 24 country representatives, to “operationalize” the new funding arrangements, including identifying funding sources. The committee is tasked with delivering a set of recommendations at COP28, which will take place next year in Dubai.

      Advising the U.N. on net zero

      Though the decisions reached at COP27 did not include major new commitments on reducing emissions from the combustion of fossil fuels, the transition to a clean global energy system was nevertheless a key topic of conversation throughout the conference.

      The Council of Engineers for the Energy Transition (CEET), an independent, international body of engineers and energy systems experts formed to provide advice to the U.N. on achieving net-zero emissions globally by 2050, convened for the first time at COP27. Jessika Trancik, a professor in the MIT Institute for Data, Systems, and Society and a member of CEET, spoke on a U.N.-sponsored panel on solutions for the transition to clean energy.

      Trancik noted that the energy transition will look different in different regions of the world. “As engineers, we need to understand those local contexts and design solutions around those local contexts — that’s absolutely essential to support a rapid and equitable energy transition.”

      At the same time, Trancik noted that there is now a set of “low-cost, ready-to-scale tools” available to every region — tools that resulted from a globally competitive process of innovation, stimulated by public policies in different countries, that dramatically drove down the costs of technologies like solar energy and lithium-ion batteries. The key, Trancik said, is for regional transition strategies to “tap into global processes of innovation.”

      Reinventing climate adaptation

      Elfatih Eltahir, the H. M. King Bhumibol Professor of Hydrology and Climate, traveled to COP27 to present plans for the Jameel Observatory Climate Resilience Early Warning System (CREWSnet), one of the five projects selected in April 2022 as a flagship in MIT’s Climate Grand Challenges initiative. CREWSnet focuses on climate adaptation, the term for adapting to climate impacts that are unavoidable.

      The aim of CREWSnet, Eltahir told the audience during a panel discussion, is “nothing short of reinventing the process of climate change adaptation,” so that it is proactive rather than reactive; community-led; data-driven and evidence-based; and so that it integrates different climate risks, from heat waves to sea level rise, rather than treating them individually.

      “However, it’s easy to talk about these changes,” said Eltahir. “The real challenge, which we are now just launching and engaging in, is to demonstrate that on the ground.” Eltahir said that early demonstrations will happen in a couple of key locations, including southwest Bangladesh, where multiple climate risks — rising sea levels, increasing soil salinity, and intensifying heat waves and cyclones — are combining to threaten the area’s agricultural production.

      Building on COP26

      Some members of MIT’s delegation attended COP27 to advance efforts that had been formally announced at last year’s U.N. climate conference, COP26, in Glasgow, Scotland.

      At an official U.N. side event co-organized by MIT on Nov. 11, Greg Sixt, the director of the Food and Climate Systems Transformation (FACT) Alliance led by the Abdul Latif Jameel Water and Food Systems Lab, provided an update on the alliance’s work since its launch at COP26.

      Food systems are a major source of greenhouse gas emissions — and are increasingly vulnerable to climate impacts. The FACT Alliance works to better connect researchers to farmers, food businesses, policymakers, and other food systems stakeholders to make food systems (which include food production, consumption, and waste) more sustainable and resilient. 

      Sixt told the audience that the FACT Alliance now counts over 20 research and stakeholder institutions around the world among its members, but also collaborates with other institutions in an “open network model” to advance work in key areas — such as a new research project exploring how climate scenarios could affect global food supply chains.

      Marcela Angel, research program director for the Environmental Solutions Initiative (ESI), helped convene a meeting at COP27 of the Afro-InterAmerican Forum on Climate Change, which also launched at COP26. The forum works with Afro-descendant leaders across the Americas to address significant environmental issues, including climate risks and biodiversity loss. 

      At the event — convened with the Colombian government and the nonprofit Conservation International — ESI brought together leaders from six countries in the Americas and presented recent work that estimates that there are over 178 million individuals who identify as Afro-descendant living in the Americas, in lands of global environmental importance. 

      “There is a significant overlap between biodiversity hot spots, protected areas, and areas of high Afro-descendant presence,” said Angel. “But the role and climate contributions of these communities is understudied, and often made invisible.”    

      Limiting methane emissions

      Methane is a short-lived but potent greenhouse gas: When released into the atmosphere, it immediately traps about 120 times more heat than carbon dioxide does. More than 150 countries have now signed the Global Methane Pledge, launched at COP26, which aims to reduce methane emissions by at least 30 percent by 2030 compared to 2020 levels.

      Sergey Paltsev, the deputy director of the Joint Program on the Science and Policy of Global Change and a senior research scientist at the MIT Energy Initiative, gave the keynote address at a Nov. 17 event on methane, where he noted the importance of methane reductions from the oil and gas sector to meeting the 2030 goal.

      “The oil and gas sector is where methane emissions reductions could be achieved the fastest,” said Paltsev. “We also need to employ an integrated approach to address methane emissions in all sectors and all regions of the world because methane emissions reductions provide a near-term pathway to avoiding dangerous tipping points in the global climate system.”

      “Keep fighting relentlessly”

      Arina Khotimsky, a senior majoring in materials science and engineering and a co-president of the MIT Energy and Climate Club, attended the first week of COP27. She reflected on the experience in a social media post after returning home. 

      “COP will always have its haters. Is there greenwashing? Of course! Is everyone who should have a say in this process in the room? Not even close,” wrote Khotimsky. “So what does it take for COP to matter? It takes everyone who attended to not only put ‘climate’ on front-page news for two weeks, but to return home and keep fighting relentlessly against climate change. I know that I will.” More

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      Reversing the charge

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      Owners of electric vehicles (EVs) are accustomed to plugging into charging stations at home and at work and filling up their batteries with electricity from the power grid. But someday soon, when these drivers plug in, their cars will also have the capacity to reverse the flow and send electrons back to the grid. As the number of EVs climbs, the fleet’s batteries could serve as a cost-effective, large-scale energy source, with potentially dramatic impacts on the energy transition, according to a new paper published by an MIT team in the journal Energy Advances.

      “At scale, vehicle-to-grid (V2G) can boost renewable energy growth, displacing the need for stationary energy storage and decreasing reliance on firm [always-on] generators, such as natural gas, that are traditionally used to balance wind and solar intermittency,” says Jim Owens, lead author and a doctoral student in the MIT Department of Chemical Engineering. Additional authors include Emre Gençer, a principal research scientist at the MIT Energy Initiative (MITEI), and Ian Miller, a research specialist for MITEI at the time of the study.

      The group’s work is the first comprehensive, systems-based analysis of future power systems, drawing on a novel mix of computational models integrating such factors as carbon emission goals, variable renewable energy (VRE) generation, and costs of building energy storage, production, and transmission infrastructure.

      “We explored not just how EVs could provide service back to the grid — thinking of these vehicles almost like energy storage on wheels — but also the value of V2G applications to the entire energy system and if EVs could reduce the cost of decarbonizing the power system,” says Gençer. “The results were surprising; I personally didn’t believe we’d have so much potential here.”

      Displacing new infrastructure

      As the United States and other nations pursue stringent goals to limit carbon emissions, electrification of transportation has taken off, with the rate of EV adoption rapidly accelerating. (Some projections show EVs supplanting internal combustion vehicles over the next 30 years.) With the rise of emission-free driving, though, there will be increased demand for energy. “The challenge is ensuring both that there’s enough electricity to charge the vehicles and that this electricity is coming from renewable sources,” says Gençer.

      But solar and wind energy is intermittent. Without adequate backup for these sources, such as stationary energy storage facilities using lithium-ion batteries, for instance, or large-scale, natural gas- or hydrogen-fueled power plants, achieving clean energy goals will prove elusive. More vexing, costs for building the necessary new energy infrastructure runs to the hundreds of billions.

      This is precisely where V2G can play a critical, and welcome, role, the researchers reported. In their case study of a theoretical New England power system meeting strict carbon constraints, for instance, the team found that participation from just 13.9 percent of the region’s 8 million light-duty (passenger) EVs displaced 14.7 gigawatts of stationary energy storage. This added up to $700 million in savings — the anticipated costs of building new storage capacity.

      Their paper also described the role EV batteries could play at times of peak demand, such as hot summer days. “V2G technology has the ability to inject electricity back into the system to cover these episodes, so we don’t need to install or invest in additional natural gas turbines,” says Owens. “The way that EVs and V2G can influence the future of our power systems is one of the most exciting and novel aspects of our study.”

      Modeling power

      To investigate the impacts of V2G on their hypothetical New England power system, the researchers integrated their EV travel and V2G service models with two of MITEI’s existing modeling tools: the Sustainable Energy System Analysis Modeling Environment (SESAME) to project vehicle fleet and electricity demand growth, and GenX, which models the investment and operation costs of electricity generation, storage, and transmission systems. They incorporated such inputs as different EV participation rates, costs of generation for conventional and renewable power suppliers, charging infrastructure upgrades, travel demand for vehicles, changes in electricity demand, and EV battery costs.

      Their analysis found benefits from V2G applications in power systems (in terms of displacing energy storage and firm generation) at all levels of carbon emission restrictions, including one with no emissions caps at all. However, their models suggest that V2G delivers the greatest value to the power system when carbon constraints are most aggressive — at 10 grams of carbon dioxide per kilowatt hour load. Total system savings from V2G ranged from $183 million to $1,326 million, reflecting EV participation rates between 5 percent and 80 percent.

      “Our study has begun to uncover the inherent value V2G has for a future power system, demonstrating that there is a lot of money we can save that would otherwise be spent on storage and firm generation,” says Owens.

      Harnessing V2G

      For scientists seeking ways to decarbonize the economy, the vision of millions of EVs parked in garages or in office spaces and plugged into the grid for 90 percent of their operating lives proves an irresistible provocation. “There is all this storage sitting right there, a huge available capacity that will only grow, and it is wasted unless we take full advantage of it,” says Gençer.

      This is not a distant prospect. Startup companies are currently testing software that would allow two-way communication between EVs and grid operators or other entities. With the right algorithms, EVs would charge from and dispatch energy to the grid according to profiles tailored to each car owner’s needs, never depleting the battery and endangering a commute.

      “We don’t assume all vehicles will be available to send energy back to the grid at the same time, at 6 p.m. for instance, when most commuters return home in the early evening,” says Gençer. He believes that the vastly varied schedules of EV drivers will make enough battery power available to cover spikes in electricity use over an average 24-hour period. And there are other potential sources of battery power down the road, such as electric school buses that are employed only for short stints during the day and then sit idle.

      The MIT team acknowledges the challenges of V2G consumer buy-in. While EV owners relish a clean, green drive, they may not be as enthusiastic handing over access to their car’s battery to a utility or an aggregator working with power system operators. Policies and incentives would help.

      “Since you’re providing a service to the grid, much as solar panel users do, you could be paid for your participation, and paid at a premium when electricity prices are very high,” says Gençer.

      “People may not be willing to participate ’round the clock, but if we have blackout scenarios like in Texas last year, or hot-day congestion on transmission lines, maybe we can turn on these vehicles for 24 to 48 hours, sending energy back to the system,” adds Owens. “If there’s a power outage and people wave a bunch of money at you, you might be willing to talk.”

      “Basically, I think this comes back to all of us being in this together, right?” says Gençer. “As you contribute to society by giving this service to the grid, you will get the full benefit of reducing system costs, and also help to decarbonize the system faster and to a greater extent.”

      Actionable insights

      Owens, who is building his dissertation on V2G research, is now investigating the potential impact of heavy-duty electric vehicles in decarbonizing the power system. “The last-mile delivery trucks of companies like Amazon and FedEx are likely to be the earliest adopters of EVs,” Owen says. “They are appealing because they have regularly scheduled routes during the day and go back to the depot at night, which makes them very useful for providing electricity and balancing services in the power system.”

      Owens is committed to “providing insights that are actionable by system planners, operators, and to a certain extent, investors,” he says. His work might come into play in determining what kind of charging infrastructure should be built, and where.

      “Our analysis is really timely because the EV market has not yet been developed,” says Gençer. “This means we can share our insights with vehicle manufacturers and system operators — potentially influencing them to invest in V2G technologies, avoiding the costs of building utility-scale storage, and enabling the transition to a cleaner future. It’s a huge win, within our grasp.”

      The research for this study was funded by MITEI’s Future Energy Systems Center. More

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      With new heat treatment, 3D-printed metals can withstand extreme conditions

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      A new MIT-developed heat treatment transforms the microscopic structure of 3D-printed metals, making the materials stronger and more resilient in extreme thermal environments. The technique could make it possible to 3D print high-performance blades and vanes for power-generating gas turbines and jet engines, which would enable new designs with improved fuel consumption and energy efficiency.

      Today’s gas turbine blades are manufactured through conventional casting processes in which molten metal is poured into complex molds and directionally solidified. These components are made from some of the most heat-resistant metal alloys on Earth, as they are designed to rotate at high speeds in extremely hot gas, extracting work to generate electricity in power plants and thrust in jet engines.

      There is growing interest in manufacturing turbine blades through 3D-printing, which, in addition to its environmental and cost benefits, could allow manufacturers to quickly produce more intricate, energy-efficient blade geometries. But efforts to 3D-print turbine blades have yet to clear a big hurdle: creep.

      In metallurgy, creep refers to a metal’s tendency to permanently deform in the face of persistent mechanical stress and high temperatures. While researchers have explored printing turbine blades, they have found that the printing process produces fine grains on the order of tens to hundreds of microns in size — a microstructure that is especially vulnerable to creep.

      “In practice, this would mean a gas turbine would have a shorter life or less fuel efficiency,” says Zachary Cordero, the Boeing Career Development Professor in Aeronautics and Astronautics at MIT. “These are costly, undesirable outcomes.”

      Cordero and his colleagues found a way to improve the structure of 3D-printed alloys by adding an additional heat-treating step, which transforms the as-printed material’s fine grains into much larger “columnar” grains — a sturdier microstructure that should minimize the material’s creep potential, since the “columns” are aligned with the axis of greatest stress. The researchers say the method, outlined today in Additive Manufacturing, clears the way for industrial 3D-printing of gas turbine blades.

      “In the near future, we envision gas turbine manufacturers will print their blades and vanes at large-scale additive manufacturing plants, then post-process them using our heat treatment,” Cordero says. “3D-printing will enable new cooling architectures that can improve the thermal efficiency of a turbine, so that it produces the same amount of power while burning less fuel and ultimately emits less carbon dioxide.”

      Cordero’s co-authors on the study are lead author Dominic Peachey, Christopher Carter, and Andres Garcia-Jimenez at MIT, Anugrahaprada Mukundan and Marie-Agathe Charpagne of the University of Illinois at Urbana-Champaign, and Donovan Leonard of Oak Ridge National Laboratory.

      Triggering a transformation

      The team’s new method is a form of directional recrystallization — a heat treatment that passes a material through a hot zone at a precisely controlled speed to meld a material’s many microscopic grains into larger, sturdier, and more uniform crystals.

      Directional recrystallization was invented more than 80 years ago and has been applied to wrought materials. In their new study, the MIT team adapted directional recrystallization for 3D-printed superalloys.

      The team tested the method on 3D-printed nickel-based superalloys — metals that are typically cast and used in gas turbines. In a series of experiments, the researchers placed 3D-printed samples of rod-shaped superalloys in a room-temperature water bath placed just below an induction coil. They slowly drew each rod out of the water and through the coil at various speeds, dramatically heating the rods to temperatures varying between 1,200 and 1,245 degrees Celsius.

      They found that drawing the rods at a particular speed (2.5 millimeters per hour) and through a specific temperature (1,235 degrees Celsius) created a steep thermal gradient that triggered a transformation in the material’s printed, fine-grained microstructure.

      “The material starts as small grains with defects called dislocations, that are like a mangled spaghetti,” Cordero explains. “When you heat this material up, those defects can annihilate and reconfigure, and the grains are able to grow. We’re continuously elongating the grains by consuming the defective material and smaller grains — a process termed recrystallization.”

      Creep away

      After cooling the heat-treated rods, the researchers examined their microstructure using optical and electron microscopy, and found that the material’s printed microscopic grains were replaced with “columnar” grains, or long crystal-like regions that were significantly larger than the original grains.

      “We’ve completely transformed the structure,” says lead author Dominic Peachey. “We show we can increase the grain size by orders of magnitude, to massive columnar grains, which theoretically should lead to dramatic improvements in creep properties.”

      The team also showed they could manipulate the draw speed and temperature of the rod samples to tailor the material’s growing grains, creating regions of specific grain size and orientation. This level of control, Cordero says, can enable manufacturers to print turbine blades with site-specific microstructures that are resilient to specific operating conditions.

      Cordero plans to test the heat treatment on 3D-printed geometries that more closely resemble turbine blades. The team is also exploring ways to speed up the draw rate, as well as test a heat-treated structure’s resistance to creep. Then, they envision that the heat treatment could enable the practical application of 3D-printing to produce industrial-grade turbine blades, with more complex shapes and patterns.

      “New blade and vane geometries will enable more energy-efficient land-based gas turbines, as well as, eventually, aeroengines,” Cordero notes. “This could from a baseline perspective lead to lower carbon dioxide emissions, just through improved efficiency of these devices.”

      This research was supported, in part, by the U.S. Office of Naval Research. More