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    Is there enough land on Earth to fight climate change and feed the world?

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    Capping global warming at 1.5 degrees Celsius is a tall order. Achieving that goal will not only require a massive reduction in greenhouse gas emissions from human activities, but also a substantial reallocation of land to support that effort and sustain the biosphere, including humans. More land will be needed to accommodate a growing demand for bioenergy and nature-based carbon sequestration while ensuring sufficient acreage for food production and ecological sustainability.The expanding role of land in a 1.5 C world will be twofold — to remove carbon dioxide from the atmosphere and to produce clean energy. Land-based carbon dioxide removal strategies include bioenergy with carbon capture and storage; direct air capture; and afforestation/reforestation and other nature-based solutions. Land-based clean energy production includes wind and solar farms and sustainable bioenergy cropland. Any decision to allocate more land for climate mitigation must also address competing needs for long-term food security and ecosystem health.Land-based climate mitigation choices vary in terms of costs — amount of land required, implications for food security, impact on biodiversity and other ecosystem services — and benefits — potential for sequestering greenhouse gases and producing clean energy.Now a study in the journal Frontiers in Environmental Science provides the most comprehensive analysis to date of competing land-use and technology options to limit global warming to 1.5 C. Led by researchers at the MIT Center for Sustainability Science and Strategy (CS3), the study applies the MIT Integrated Global System Modeling (IGSM) framework to evaluate costs and benefits of different land-based climate mitigation options in Sky2050, a 1.5 C climate-stabilization scenario developed by Shell.Under this scenario, demand for bioenergy and natural carbon sinks increase along with the need for sustainable farming and food production. To determine if there’s enough land to meet all these growing demands, the research team uses the global hectare (gha) — an area of 10,000 square meters, or 2.471 acres — as the standard unit of measurement, and current estimates of the Earth’s total habitable land area (about 10 gha) and land area used for food production and bioenergy (5 gha).The team finds that with transformative changes in policy, land management practices, and consumption patterns, global land is sufficient to provide a sustainable supply of food and ecosystem services throughout this century while also reducing greenhouse gas emissions in alignment with the 1.5 C goal. These transformative changes include policies to protect natural ecosystems; stop deforestation and accelerate reforestation and afforestation; promote advances in sustainable agriculture technology and practice; reduce agricultural and food waste; and incentivize consumers to purchase sustainably produced goods.If such changes are implemented, 2.5–3.5 gha of land would be used for NBS practices to sequester 3–6 gigatonnes (Gt) of CO2 per year, and 0.4–0.6 gha of land would be allocated for energy production — 0.2–0.3 gha for bioenergy and 0.2–0.35 gha for wind and solar power generation.“Our scenario shows that there is enough land to support a 1.5 degree C future as long as effective policies at national and global levels are in place,” says CS3 Principal Research Scientist Angelo Gurgel, the study’s lead author. “These policies must not only promote efficient use of land for food, energy, and nature, but also be supported by long-term commitments from government and industry decision-makers.” More

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      Reality check on technologies to remove carbon dioxide from the air

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      In 2015, 195 nations plus the European Union signed the Paris Agreement and pledged to undertake plans designed to limit the global temperature increase to 1.5 degrees Celsius. Yet in 2023, the world exceeded that target for most, if not all of, the year — calling into question the long-term feasibility of achieving that target.To do so, the world must reduce the levels of greenhouse gases in the atmosphere, and strategies for achieving levels that will “stabilize the climate” have been both proposed and adopted. Many of those strategies combine dramatic cuts in carbon dioxide (CO2) emissions with the use of direct air capture (DAC), a technology that removes CO2 from the ambient air. As a reality check, a team of researchers in the MIT Energy Initiative (MITEI) examined those strategies, and what they found was alarming: The strategies rely on overly optimistic — indeed, unrealistic — assumptions about how much CO2 could be removed by DAC. As a result, the strategies won’t perform as predicted. Nevertheless, the MITEI team recommends that work to develop the DAC technology continue so that it’s ready to help with the energy transition — even if it’s not the silver bullet that solves the world’s decarbonization challenge.DAC: The promise and the realityIncluding DAC in plans to stabilize the climate makes sense. Much work is now under way to develop DAC systems, and the technology looks promising. While companies may never run their own DAC systems, they can already buy “carbon credits” based on DAC. Today, a multibillion-dollar market exists on which entities or individuals that face high costs or excessive disruptions to reduce their own carbon emissions can pay others to take emissions-reducing actions on their behalf. Those actions can involve undertaking new renewable energy projects or “carbon-removal” initiatives such as DAC or afforestation/reforestation (planting trees in areas that have never been forested or that were forested in the past). DAC-based credits are especially appealing for several reasons, explains Howard Herzog, a senior research engineer at MITEI. With DAC, measuring and verifying the amount of carbon removed is straightforward; the removal is immediate, unlike with planting forests, which may take decades to have an impact; and when DAC is coupled with CO2 storage in geologic formations, the CO2 is kept out of the atmosphere essentially permanently — in contrast to, for example, sequestering it in trees, which may one day burn and release the stored CO2.Will current plans that rely on DAC be effective in stabilizing the climate in the coming years? To find out, Herzog and his colleagues Jennifer Morris and Angelo Gurgel, both MITEI principal research scientists, and Sergey Paltsev, a MITEI senior research scientist — all affiliated with the MIT Center for Sustainability Science and Strategy (CS3) — took a close look at the modeling studies on which those plans are based.Their investigation identified three unavoidable engineering challenges that together lead to a fourth challenge — high costs for removing a single ton of CO2 from the atmosphere. The details of their findings are reported in a paper published in the journal One Earth on Sept. 20.Challenge 1: Scaling upWhen it comes to removing CO2 from the air, nature presents “a major, non-negotiable challenge,” notes the MITEI team: The concentration of CO2 in the air is extremely low — just 420 parts per million, or roughly 0.04 percent. In contrast, the CO2 concentration in flue gases emitted by power plants and industrial processes ranges from 3 percent to 20 percent. Companies now use various carbon capture and sequestration (CCS) technologies to capture CO2 from their flue gases, but capturing CO2 from the air is much more difficult. To explain, the researchers offer the following analogy: “The difference is akin to needing to find 10 red marbles in a jar of 25,000 marbles of which 24,990 are blue [the task representing DAC] versus needing to find about 10 red marbles in a jar of 100 marbles of which 90 are blue [the task for CCS].”Given that low concentration, removing a single metric ton (tonne) of CO2 from air requires processing about 1.8 million cubic meters of air, which is roughly equivalent to the volume of 720 Olympic-sized swimming pools. And all that air must be moved across a CO2-capturing sorbent — a feat requiring large equipment. For example, one recently proposed design for capturing 1 million tonnes of CO2 per year would require an “air contactor” equivalent in size to a structure about three stories high and three miles long.Recent modeling studies project DAC deployment on the scale of 5 to 40 gigatonnes of CO2 removed per year. (A gigatonne equals 1 billion metric tonnes.) But in their paper, the researchers conclude that the likelihood of deploying DAC at the gigatonne scale is “highly uncertain.”Challenge 2: Energy requirementGiven the low concentration of CO2 in the air and the need to move large quantities of air to capture it, it’s no surprise that even the best DAC processes proposed today would consume large amounts of energy — energy that’s generally supplied by a combination of electricity and heat. Including the energy needed to compress the captured CO2 for transportation and storage, most proposed processes require an equivalent of at least 1.2 megawatt-hours of electricity for each tonne of CO2 removed.The source of that electricity is critical. For example, using coal-based electricity to drive an all-electric DAC process would generate 1.2 tonnes of CO2 for each tonne of CO2 captured. The result would be a net increase in emissions, defeating the whole purpose of the DAC. So clearly, the energy requirement must be satisfied using either low-carbon electricity or electricity generated using fossil fuels with CCS. All-electric DAC deployed at large scale — say, 10 gigatonnes of CO2 removed annually — would require 12,000 terawatt-hours of electricity, which is more than 40 percent of total global electricity generation today.Electricity consumption is expected to grow due to increasing overall electrification of the world economy, so low-carbon electricity will be in high demand for many competing uses — for example, in power generation, transportation, industry, and building operations. Using clean electricity for DAC instead of for reducing CO2 emissions in other critical areas raises concerns about the best uses of clean electricity.Many studies assume that a DAC unit could also get energy from “waste heat” generated by some industrial process or facility nearby. In the MITEI researchers’ opinion, “that may be more wishful thinking than reality.” The heat source would need to be within a few miles of the DAC plant for transporting the heat to be economical; given its high capital cost, the DAC plant would need to run nonstop, requiring constant heat delivery; and heat at the temperature required by the DAC plant would have competing uses, for example, for heating buildings. Finally, if DAC is deployed at the gigatonne per year scale, waste heat will likely be able to provide only a small fraction of the needed energy.Challenge 3: SitingSome analysts have asserted that, because air is everywhere, DAC units can be located anywhere. But in reality, siting a DAC plant involves many complex issues. As noted above, DAC plants require significant amounts of energy, so having access to enough low-carbon energy is critical. Likewise, having nearby options for storing the removed CO2 is also critical. If storage sites or pipelines to such sites don’t exist, major new infrastructure will need to be built, and building new infrastructure of any kind is expensive and complicated, involving issues related to permitting, environmental justice, and public acceptability — issues that are, in the words of the researchers, “commonly underestimated in the real world and neglected in models.”Two more siting needs must be considered. First, meteorological conditions must be acceptable. By definition, any DAC unit will be exposed to the elements, and factors like temperature and humidity will affect process performance and process availability. And second, a DAC plant will require some dedicated land — though how much is unclear, as the optimal spacing of units is as yet unresolved. Like wind turbines, DAC units need to be properly spaced to ensure maximum performance such that one unit is not sucking in CO2-depleted air from another unit.Challenge 4: CostConsidering the first three challenges, the final challenge is clear: the cost per tonne of CO2 removed is inevitably high. Recent modeling studies assume DAC costs as low as $100 to $200 per ton of CO2 removed. But the researchers found evidence suggesting far higher costs.To start, they cite typical costs for power plants and industrial sites that now use CCS to remove CO2 from their flue gases. The cost of CCS in such applications is estimated to be in the range of $50 to $150 per ton of CO2 removed. As explained above, the far lower concentration of CO2 in the air will lead to substantially higher costs.As explained under Challenge 1, the DAC units needed to capture the required amount of air are massive. The capital cost of building them will be high, given labor, materials, permitting costs, and so on. Some estimates in the literature exceed $5,000 per tonne captured per year.Then there are the ongoing costs of energy. As noted under Challenge 2, removing 1 tonne of CO2 requires the equivalent of 1.2 megawatt-hours of electricity. If that electricity costs $0.10 per kilowatt-hour, the cost of just the electricity needed to remove 1 tonne of CO2 is $120. The researchers point out that assuming such a low price is “questionable,” given the expected increase in electricity demand, future competition for clean energy, and higher costs on a system dominated by renewable — but intermittent — energy sources.Then there’s the cost of storage, which is ignored in many DAC cost estimates.Clearly, many considerations show that prices of $100 to $200 per tonne are unrealistic, and assuming such low prices will distort assessments of strategies, leading them to underperform going forward.The bottom lineIn their paper, the MITEI team calls DAC a “very seductive concept.” Using DAC to suck CO2 out of the air and generate high-quality carbon-removal credits can offset reduction requirements for industries that have hard-to-abate emissions. By doing so, DAC would minimize disruptions to key parts of the world’s economy, including air travel, certain carbon-intensive industries, and agriculture. However, the world would need to generate billions of tonnes of CO2 credits at an affordable price. That prospect doesn’t look likely. The largest DAC plant in operation today removes just 4,000 tonnes of CO2 per year, and the price to buy the company’s carbon-removal credits on the market today is $1,500 per tonne.The researchers recognize that there is room for energy efficiency improvements in the future, but DAC units will always be subject to higher work requirements than CCS applied to power plant or industrial flue gases, and there is not a clear pathway to reducing work requirements much below the levels of current DAC technologies.Nevertheless, the researchers recommend that work to develop DAC continue “because it may be needed for meeting net-zero emissions goals, especially given the current pace of emissions.” But their paper concludes with this warning: “Given the high stakes of climate change, it is foolhardy to rely on DAC to be the hero that comes to our rescue.” More

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      Ensuring a durable transition

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      To fend off the worst impacts of climate change, “we have to decarbonize, and do it even faster,” said William H. Green, director of the MIT Energy Initiative (MITEI) and Hoyt C. Hottel Professor, MIT Department of Chemical Engineering, at MITEI’s Annual Research Conference.“But how the heck do we actually achieve this goal when the United States is in the middle of a divisive election campaign, and globally, we’re facing all kinds of geopolitical conflicts, trade protectionism, weather disasters, increasing demand from developing countries building a middle class, and data centers in countries like the U.S.?”Researchers, government officials, and business leaders convened in Cambridge, Massachusetts, Sept. 25-26 to wrestle with this vexing question at the conference that was themed, “A durable energy transition: How to stay on track in the face of increasing demand and unpredictable obstacles.”“In this room we have a lot of power,” said Green, “if we work together, convey to all of society what we see as real pathways and policies to solve problems, and take collective action.”The critical role of consensus-building in driving the energy transition arose repeatedly in conference sessions, whether the topic involved developing and adopting new technologies, constructing and siting infrastructure, drafting and passing vital energy policies, or attracting and retaining a skilled workforce.Resolving conflictsThere is “blowback and a social cost” in transitioning away from fossil fuels, said Stephen Ansolabehere, the Frank G. Thompson Professor of Government at Harvard University, in a panel on the social barriers to decarbonization. “Companies need to engage differently and recognize the rights of communities,” he said.Nora DeDontney, director of development at Vineyard Offshore, described her company’s two years of outreach and negotiations to bring large cables from ocean-based wind turbines onshore.“Our motto is, ‘community first,’” she said. Her company works to mitigate any impacts towns might feel because of offshore wind infrastructure construction with projects, such as sewer upgrades; provides workforce training to Tribal Nations; and lays out wind turbines in a manner that provides safe and reliable areas for local fisheries.Elsa A. Olivetti, professor in the Department of Materials Science and Engineering at MIT and the lead of the Decarbonization Mission of MIT’s new Climate Project, discussed the urgent need for rapid scale-up of mineral extraction. “Estimates indicate that to electrify the vehicle fleet by 2050, about six new large copper mines need to come on line each year,” she said. To meet the demand for metals in the United States means pushing into Indigenous lands and environmentally sensitive habitats. “The timeline of permitting is not aligned with the temporal acceleration needed,” she said.Larry Susskind, the Ford Professor of Urban and Environmental Planning in the MIT Department of Urban Studies and Planning, is trying to resolve such tensions with universities playing the role of mediators. He is creating renewable energy clinics where students train to participate in emerging disputes over siting. “Talk to people before decisions are made, conduct joint fact finding, so that facilities reduce harms and share the benefits,” he said.Clean energy boom and pressureA relatively recent and unforeseen increase in demand for energy comes from data centers, which are being built by large technology companies for new offerings, such as artificial intelligence.“General energy demand was flat for 20 years — and now, boom,” said Sean James, Microsoft’s senior director of data center research. “It caught utilities flatfooted.” With the expansion of AI, the rush to provision data centers with upwards of 35 gigawatts of new (and mainly renewable) power in the near future, intensifies pressure on big companies to balance the concerns of stakeholders across multiple domains. Google is pursuing 24/7 carbon-free energy by 2030, said Devon Swezey, the company’s senior manager for global energy and climate.“We’re pursuing this by purchasing more and different types of clean energy locally, and accelerating technological innovation such as next-generation geothermal projects,” he said. Pedro Gómez Lopez, strategy and development director, Ferrovial Digital, which designs and constructs data centers, incorporates renewable energy into their projects, which contributes to decarbonization goals and benefits to locales where they are sited. “We can create a new supply of power, taking the heat generated by a data center to residences or industries in neighborhoods through District Heating initiatives,” he said.The Inflation Reduction Act and other legislation has ramped up employment opportunities in clean energy nationwide, touching every region, including those most tied to fossil fuels. “At the start of 2024 there were about 3.5 million clean energy jobs, with ‘red’ states showing the fastest growth in clean energy jobs,” said David S. Miller, managing partner at Clean Energy Ventures. “The majority (58 percent) of new jobs in energy are now in clean energy — that transition has happened. And one-in-16 new jobs nationwide were in clean energy, with clean energy jobs growing more than three times faster than job growth economy-wide”In this rapid expansion, the U.S. Department of Energy (DoE) is prioritizing economically marginalized places, according to Zoe Lipman, lead for good jobs and labor standards in the Office of Energy Jobs at the DoE. “The community benefit process is integrated into our funding,” she said. “We are creating the foundation of a virtuous circle,” encouraging benefits to flow to disadvantaged and energy communities, spurring workforce training partnerships, and promoting well-paid union jobs. “These policies incentivize proactive community and labor engagement, and deliver community benefits, both of which are key to building support for technological change.”Hydrogen opportunity and challengeWhile engagement with stakeholders helps clear the path for implementation of technology and the spread of infrastructure, there remain enormous policy, scientific, and engineering challenges to solve, said multiple conference participants. In a “fireside chat,” Prasanna V. Joshi, vice president of low-carbon-solutions technology at ExxonMobil, and Ernest J. Moniz, professor of physics and special advisor to the president at MIT, discussed efforts to replace natural gas and coal with zero-carbon hydrogen in order to reduce greenhouse gas emissions in such major industries as steel and fertilizer manufacturing.“We have gone into an era of industrial policy,” said Moniz, citing a new DoE program offering incentives to generate demand for hydrogen — more costly than conventional fossil fuels — in end-use applications. “We are going to have to transition from our current approach, which I would call carrots-and-twigs, to ultimately, carrots-and-sticks,” Moniz warned, in order to create “a self-sustaining, major, scalable, affordable hydrogen economy.”To achieve net zero emissions by 2050, ExxonMobil intends to use carbon capture and sequestration in natural gas-based hydrogen and ammonia production. Ammonia can also serve as a zero-carbon fuel. Industry is exploring burning ammonia directly in coal-fired power plants to extend the hydrogen value chain. But there are challenges. “How do you burn 100 percent ammonia?”, asked Joshi. “That’s one of the key technology breakthroughs that’s needed.” Joshi believes that collaboration with MIT’s “ecosystem of breakthrough innovation” will be essential to breaking logjams around the hydrogen and ammonia-based industries.MIT ingenuity essentialThe energy transition is placing very different demands on different regions around the world. Take India, where today per capita power consumption is one of the lowest. But Indians “are an aspirational people … and with increasing urbanization and industrial activity, the growth in power demand is expected to triple by 2050,” said Praveer Sinha, CEO and managing director of the Tata Power Co. Ltd., in his keynote speech. For that nation, which currently relies on coal, the move to clean energy means bringing another 300 gigawatts of zero-carbon capacity online in the next five years. Sinha sees this power coming from wind, solar, and hydro, supplemented by nuclear energy.“India plans to triple nuclear power generation capacity by 2032, and is focusing on advancing small modular reactors,” said Sinha. “The country also needs the rapid deployment of storage solutions to firm up the intermittent power.” The goal is to provide reliable electricity 24/7 to a population living both in large cities and in geographically remote villages, with the help of long-range transmission lines and local microgrids. “India’s energy transition will require innovative and affordable technology solutions, and there is no better place to go than MIT, where you have the best brains, startups, and technology,” he said.These assets were on full display at the conference. Among them a cluster of young businesses, including:the MIT spinout Form Energy, which has developed a 100-hour iron battery as a backstop to renewable energy sources in case of multi-day interruptions;startup Noya that aims for direct air capture of atmospheric CO2 using carbon-based materials;the firm Active Surfaces, with a lightweight material for putting solar photovoltaics in previously inaccessible places;Copernic Catalysts, with new chemistry for making ammonia and sustainable aviation fuel far more inexpensively than current processes; andSesame Sustainability, a software platform spun out of MITEI that gives industries a full financial analysis of the costs and benefits of decarbonization.The pipeline of research talent extended into the undergraduate ranks, with a conference “slam” competition showcasing students’ summer research projects in areas from carbon capture using enzymes to 3D design for the coils used in fusion energy confinement.“MIT students like me are looking to be the next generation of energy leaders, looking for careers where we can apply our engineering skills to tackle exciting climate problems and make a tangible impact,” said Trent Lee, a junior in mechanical engineering researching improvements in lithium-ion energy storage. “We are stoked by the energy transition, because it’s not just the future, but our chance to build it.” More

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      in Environment

      MIT engineers make converting CO2 into useful products more practical

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      As the world struggles to reduce greenhouse gas emissions, researchers are seeking practical, economical ways to capture carbon dioxide and convert it into useful products, such as transportation fuels, chemical feedstocks, or even building materials. But so far, such attempts have struggled to reach economic viability.New research by engineers at MIT could lead to rapid improvements in a variety of electrochemical systems that are under development to convert carbon dioxide into a valuable commodity. The team developed a new design for the electrodes used in these systems, which increases the efficiency of the conversion process.The findings are reported today in the journal Nature Communications, in a paper by MIT doctoral student Simon Rufer, professor of mechanical engineering Kripa Varanasi, and three others.“The CO2 problem is a big challenge for our times, and we are using all kinds of levers to solve and address this problem,” Varanasi says. It will be essential to find practical ways of removing the gas, he says, either from sources such as power plant emissions, or straight out of the air or the oceans. But then, once the CO2 has been removed, it has to go somewhere.A wide variety of systems have been developed for converting that captured gas into a useful chemical product, Varanasi says. “It’s not that we can’t do it — we can do it. But the question is how can we make this efficient? How can we make this cost-effective?”In the new study, the team focused on the electrochemical conversion of CO2 to ethylene, a widely used chemical that can be made into a variety of plastics as well as fuels, and which today is made from petroleum. But the approach they developed could also be applied to producing other high-value chemical products as well, including methane, methanol, carbon monoxide, and others, the researchers say.Currently, ethylene sells for about $1,000 per ton, so the goal is to be able to meet or beat that price. The electrochemical process that converts CO2 into ethylene involves a water-based solution and a catalyst material, which come into contact along with an electric current in a device called a gas diffusion electrode.There are two competing characteristics of the gas diffusion electrode materials that affect their performance: They must be good electrical conductors so that the current that drives the process doesn’t get wasted through resistance heating, but they must also be “hydrophobic,” or water repelling, so the water-based electrolyte solution doesn’t leak through and interfere with the reactions taking place at the electrode surface.Unfortunately, it’s a tradeoff. Improving the conductivity reduces the hydrophobicity, and vice versa. Varanasi and his team set out to see if they could find a way around that conflict, and after many months of trying, they did just that.The solution, devised by Rufer and Varanasi, is elegant in its simplicity. They used a plastic material, PTFE (essentially Teflon), that has been known to have good hydrophobic properties. However, PTFE’s lack of conductivity means that electrons must travel through a very thin catalyst layer, leading to significant voltage drop with distance. To overcome this limitation, the researchers wove a series of conductive copper wires through the very thin sheet of the PTFE.“This work really addressed this challenge, as we can now get both conductivity and hydrophobicity,” Varanasi says.Research on potential carbon conversion systems tends to be done on very small, lab-scale samples, typically less than 1-inch (2.5-centimeter) squares. To demonstrate the potential for scaling up, Varanasi’s team produced a sheet 10 times larger in area and demonstrated its effective performance.To get to that point, they had to do some basic tests that had apparently never been done before, running tests under identical conditions but using electrodes of different sizes to analyze the relationship between conductivity and electrode size. They found that conductivity dropped off dramatically with size, which would mean much more energy, and thus cost, would be needed to drive the reaction.“That’s exactly what we would expect, but it was something that nobody had really dedicatedly investigated before,” Rufer says. In addition, the larger sizes produced more unwanted chemical byproducts besides the intended ethylene.Real-world industrial applications would require electrodes that are perhaps 100 times larger than the lab versions, so adding the conductive wires will be necessary for making such systems practical, the researchers say. They also developed a model which captures the spatial variability in voltage and product distribution on electrodes due to ohmic losses. The model along with the experimental data they collected enabled them to calculate the optimal spacing for conductive wires to counteract the drop off in conductivity.In effect, by weaving the wire through the material, the material is divided into smaller subsections determined by the spacing of the wires. “We split it into a bunch of little subsegments, each of which is effectively a smaller electrode,” Rufer says. “And as we’ve seen, small electrodes can work really well.”Because the copper wire is so much more conductive than the PTFE material, it acts as a kind of superhighway for electrons passing through, bridging the areas where they are confined to the substrate and face greater resistance.To demonstrate that their system is robust, the researchers ran a test electrode for 75 hours continuously, with little change in performance. Overall, Rufer says, their system “is the first PTFE-based electrode which has gone beyond the lab scale on the order of 5 centimeters or smaller. It’s the first work that has progressed into a much larger scale and has done so without sacrificing efficiency.”The weaving process for incorporating the wire can be easily integrated into existing manufacturing processes, even in a large-scale roll-to-roll process, he adds.“Our approach is very powerful because it doesn’t have anything to do with the actual catalyst being used,” Rufer says. “You can sew this micrometric copper wire into any gas diffusion electrode you want, independent of catalyst morphology or chemistry. So, this approach can be used to scale anybody’s electrode.”“Given that we will need to process gigatons of CO2 annually to combat the CO2 challenge, we really need to think about solutions that can scale,” Varanasi says. “Starting with this mindset enables us to identify critical bottlenecks and develop innovative approaches that can make a meaningful impact in solving the problem. Our hierarchically conductive electrode is a result of such thinking.”The research team included MIT graduate students Michael Nitzsche and Sanjay Garimella,  as well as Jack Lake PhD ’23. The work was supported by Shell, through the MIT Energy Initiative. More

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      Preparing Taiwan for a decarbonized economy

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      The operations of Taiwan’s electronics, manufacturing, and financial firms vary widely, but their leaders all have at least one thing in common: They recognize the role that a changing energy landscape will play in their future success, and they’re actively planning for that transition.“They’re all interested in how Taiwan can supply energy for its economy going forward — energy that meets global goals for decarbonization,” says Robert C. Armstrong, the Chevron Professor of Chemical Engineering Emeritus at MIT, as well as a principal investigator for the Taiwan Innovative Green Economy Roadmap (TIGER) program. “Each company is going to have its own particular needs. For example, financial companies have data centers that need energy 24/7, with no interruptions. But the need for a robust, reliable, resilient energy system is shared among all of them.”Ten Taiwanese companies are participating in TIGER, a two-year program with the MIT Energy Initiative (MITEI) to explore various ways that industry and government can promote and adopt technologies, practices, and policies that will keep Taiwan competitive amid a quickly changing energy landscape. MIT research teams are exploring a set of six topics during the first year of the program, with plans to tackle a second set of topics during the second year, eventually leading to a roadmap to green energy security for Taiwan.“We are helping them to understand green energy technologies, we are helping them to understand how policies around the world might affect supply chains, and we are helping them to understand different pathways for their domestic policies,” says Sergey Paltsev, a principal investigator for the TIGER program, as well as a deputy director of the MIT Center for Sustainability Science and Strategy and a senior research scientist at MITEI. “We are looking at how Taiwan will be affected in terms of the cost of doing business and how to preserve the competitive advantage of its export-oriented industries.”“The biggest question,” Paltsev adds, “is how Taiwanese companies can decarbonize their energy in a sustainable manner.”Why Taiwan?Paul Hsu, founding partner of the Taiwanese business consultancy Paul Hsu and Partners (one of the 10 participating TIGER companies), as well as founding chair and current board member of the Epoch Foundation, has been working for more than 30 years to forge collaborations between business leaders in Taiwan and MIT researchers. The energy challenges facing Taiwanese businesses, as well as their place in the global supply chain, make the TIGER program critical not only to improve environmental sustainability, but also to ensure future competitiveness, he says. “The energy field is facing revolution,” Hsu says. “Taiwanese companies are not operating in Taiwan alone, but also operating worldwide, and we are affected by the global supply chain. We need to diversify our businesses and our energy resources, and the first thing we’re looking for in this partnership is education — an understanding about how to orient Taiwanese industry toward the future of energy.”Wendy Duan, the program director of the Asia Pacific program at MITEI, notes that Taiwan has a number of similarities to places such as Singapore and Japan. The lessons learned through the TIGER program, she says, will likely be applicable — at least on some level — to other markets throughout Asia, and even around the world.“Taiwan is very much dependent on imported energy,” Duan notes. “Many countries in East Asia are facing similar challenges, and if Taiwan has a good roadmap for the future of energy, it can be a good role model.”“Taiwan is a great place for this sort of collaboration,” Armstrong says. “Their industry is very innovative, and it’s a place where businesses are willing to implement new, important ideas. At the same time, their economy is highly dependent on trade, and they import a lot of fossil fuels today. To compete in a decarbonized global economy, they’re going to have to find alternatives to that. If you can develop a path from today’s economy in Taiwan to a future manufacturing economy that is decarbonized, then that gives you a lot of interesting tools you could bring to bear in other economies.”Uncovering solutionsStakeholders from MIT and the participating companies meet for monthly webinars and biannual in-person workshops (alternating between Cambridge, Massachusetts, and Taipei) to discuss progress. The research addresses options for Taiwan to increase its supply of green energy, methods for storing and distributing that energy more efficiently, policy levers for implementing these changes, and Taiwan’s place in the global energy economy.“The project on the electric grid, the project on storage, and the project on hydrogen — all three of those are related to the issue of how to decarbonize power generation and delivery,” notes Paltsev. “But we also need to understand how things in other parts of the world are going to affect demand for the products that are produced in Taiwan. If there is a huge change in demand for certain products due to decarbonization, Taiwanese companies are going to feel it. Therefore, the companies want to understand where the demand is going to be coming from, and how to adjust their business strategies.”One of the research projects is looking closely at advanced nuclear power. There are significant political roadblocks standing in the way, but business leaders are intrigued by the prospect of nuclear energy in Taiwan, where available land for wind and solar power generation is sparse.“So far, Taiwan government policy is anti-nuclear,” Hsu says. “The current ruling party is against it. They are still thinking about what happened in the 1960s and 1970s, and they think nuclear is very dangerous. But if you look into it, nuclear generation technology has really improved.”Implementing a green economy roadmapTIGER participants’ interest in green energy solutions is, of course, not merely academic. Ultimately, the success of the program will be determined not only by the insights from the research produced over these two years, but by how these findings constructively inform both the private and public sectors.“MIT and TIGER participants are united in their commitment to advancing regional industrial and economic development, while championing decarbonization and sustainability efforts in Taiwan,” Duan says. “MIT researchers are informed by insights and domain expertise contributed by TIGER participants, believing that their collaborative efforts can help other nations facing similar geo-economic challenges.”“We are helping the companies understand how to stay leaders in this changing world,” says Paltsev. “We want to make sure that we are not painting an unrealistically rosy picture, or conveying that it will be easy to decarbonize. On the contrary, we want to stay realistic and try to show them both where they can make advances and where we see challenges.”The goal, Armstrong says, is not energy independence for Taiwan, but rather energy security. “Energy security requires diversity of supply,” he says. “So, you have a diverse set of suppliers, who are trusted trading partners, but it doesn’t mean you’re on your own. That’s the goal for Taiwan.”What will that mean, more specifically? Well, that’s what TIGER researchers aim to learn. “It probably means a mix of energy sources,” Armstrong says. “It could be that nuclear fission provides a core of energy that companies need for their industrial operations, it could be that they can import hydrogen in the form of ammonia or another carrier, and it could be that they leverage the renewable resources they have, together with storage technologies, to provide some pretty inexpensive energy for their manufacturing sector.”“We don’t know,” Armstrong adds. “But that’s what we’re looking at, to see if we can figure out a pathway that gets them to their goals. We are optimistic that we can get there.”The companies participating in the TIGER program include AcBel Polytech Inc., CDIB Capital Group / KGI Bank Co., Ltd.; Delta Electronics, Inc.; Fubon Financial Holding Co., Ltd.; Paul Hsu and Partners Co., Ltd.; Ta Ya Electric Wire & Cable Co., Ltd.; TCC Group Holdings Co. Ltd.; Walsin Lihwa Corporation; Wistron Corporation; and Zhen Ding Technology Holding, Ltd. More

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      Study: Fusion energy could play a major role in the global response to climate change

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      For many decades, fusion has been touted as the ultimate source of abundant, clean electricity. Now, as the world faces the need to reduce carbon emissions to prevent catastrophic climate change, making commercial fusion power a reality takes on new importance. In a power system dominated by low-carbon variable renewable energy sources (VREs) such as solar and wind, “firm” electricity sources are needed to kick in whenever demand exceeds supply — for example, when the sun isn’t shining or the wind isn’t blowing and energy storage systems aren’t up to the task. What is the potential role and value of fusion power plants (FPPs) in such a future electric power system — a system that is not only free of carbon emissions but also capable of meeting the dramatically increased global electricity demand expected in the coming decades?Working together for a year-and-a-half, investigators in the MIT Energy Initiative (MITEI) and the MIT Plasma Science and Fusion Center (PSFC) have been collaborating to answer that question. They found that — depending on its future cost and performance — fusion has the potential to be critically important to decarbonization. Under some conditions, the availability of FPPs could reduce the global cost of decarbonizing by trillions of dollars. More than 25 experts together examined the factors that will impact the deployment of FPPs, including costs, climate policy, operating characteristics, and other factors. They present their findings in a new report funded through MITEI and entitled “The Role of Fusion Energy in a Decarbonized Electricity System.”“Right now, there is great interest in fusion energy in many quarters — from the private sector to government to the general public,” says the study’s principal investigator (PI) Robert C. Armstrong, MITEI’s former director and the Chevron Professor of Chemical Engineering, Emeritus. “In undertaking this study, our goal was to provide a balanced, fact-based, analysis-driven guide to help us all understand the prospects for fusion going forward.” Accordingly, the study takes a multidisciplinary approach that combines economic modeling, electric grid modeling, techno-economic analysis, and more to examine important factors that are likely to shape the future deployment and utilization of fusion energy. The investigators from MITEI provided the energy systems modeling capability, while the PSFC participants provided the fusion expertise.Fusion technologies may be a decade away from commercial deployment, so the detailed technology and costs of future commercial FPPs are not known at this point. As a result, the MIT research team focused on determining what cost levels fusion plants must reach by 2050 to achieve strong market penetration and make a significant contribution to the decarbonization of global electricity supply in the latter half of the century.The value of having FPPs available on an electric grid will depend on what other options are available, so to perform their analyses, the researchers needed estimates of the future cost and performance of those options, including conventional fossil fuel generators, nuclear fission power plants, VRE generators, and energy storage technologies, as well as electricity demand for specific regions of the world. To find the most reliable data, they searched the published literature as well as results of previous MITEI and PSFC analyses.Overall, the analyses showed that — while the technology demands of harnessing fusion energy are formidable — so are the potential economic and environmental payoffs of adding this firm, low-carbon technology to the world’s portfolio of energy options.Perhaps the most remarkable finding is the “societal value” of having commercial FPPs available. “Limiting warming to 1.5 degrees C requires that the world invest in wind, solar, storage, grid infrastructure, and everything else needed to decarbonize the electric power system,” explains Randall Field, executive director of the fusion study and MITEI’s director of research. “The cost of that task can be far lower when FPPs are available as a source of clean, firm electricity.” And the benefit varies depending on the cost of the FPPs. For example, assuming that the cost of building a FPP is $8,000 per kilowatt (kW) in 2050 and falls to $4,300/kW in 2100, the global cost of decarbonizing electric power drops by $3.6 trillion. If the cost of a FPP is $5,600/kW in 2050 and falls to $3,000/kW in 2100, the savings from having the fusion plants available would be $8.7 trillion. (Those calculations are based on differences in global gross domestic product and assume a discount rate of 6 percent. The undiscounted value is about 20 times larger.)The goal of other analyses was to determine the scale of deployment worldwide at selected FPP costs. Again, the results are striking. For a deep decarbonization scenario, the total global share of electricity generation from fusion in 2100 ranges from less than 10 percent if the cost of fusion is high to more than 50 percent if the cost of fusion is low.Other analyses showed that the scale and timing of fusion deployment vary in different parts of the world. Early deployment of fusion can be expected in wealthy nations such as European countries and the United States that have the most aggressive decarbonization policies. But certain other locations — for example, India and the continent of Africa — will have great growth in fusion deployment in the second half of the century due to a large increase in demand for electricity during that time. “In the U.S. and Europe, the amount of demand growth will be low, so it’ll be a matter of switching away from dirty fuels to fusion,” explains Sergey Paltsev, deputy director of the MIT Center for Sustainability Science and Strategy and a senior research scientist at MITEI. “But in India and Africa, for example, the tremendous growth in overall electricity demand will be met with significant amounts of fusion along with other low-carbon generation resources in the later part of the century.”A set of analyses focusing on nine subregions of the United States showed that the availability and cost of other low-carbon technologies, as well as how tightly carbon emissions are constrained, have a major impact on how FPPs would be deployed and used. In a decarbonized world, FPPs will have the highest penetration in locations with poor diversity, capacity, and quality of renewable resources, and limits on carbon emissions will have a big impact. For example, the Atlantic and Southeast subregions have low renewable resources. In those subregions, wind can produce only a small fraction of the electricity needed, even with maximum onshore wind buildout. Thus, fusion is needed in those subregions, even when carbon constraints are relatively lenient, and any available FPPs would be running much of the time. In contrast, the Central subregion of the United States has excellent renewable resources, especially wind. Thus, fusion competes in the Central subregion only when limits on carbon emissions are very strict, and FPPs will typically be operated only when the renewables can’t meet demand.An analysis of the power system that serves the New England states provided remarkably detailed results. Using a modeling tool developed at MITEI, the fusion team explored the impact of using different assumptions about not just cost and emissions limits but even such details as potential land-use constraints affecting the use of specific VREs. This approach enabled them to calculate the FPP cost at which fusion units begin to be installed. They were also able to investigate how that “threshold” cost changed with changes in the cap on carbon emissions. The method can even show at what price FPPs begin to replace other specific generating sources. In one set of runs, they determined the cost at which FPPs would begin to displace floating platform offshore wind and rooftop solar.“This study is an important contribution to fusion commercialization because it provides economic targets for the use of fusion in the electricity markets,” notes Dennis G. Whyte, co-PI of the fusion study, former director of the PSFC, and the Hitachi America Professor of Engineering in the Department of Nuclear Science and Engineering. “It better quantifies the technical design challenges for fusion developers with respect to pricing, availability, and flexibility to meet changing demand in the future.”The researchers stress that while fission power plants are included in the analyses, they did not perform a “head-to-head” comparison between fission and fusion, because there are too many unknowns. Fusion and nuclear fission are both firm, low-carbon electricity-generating technologies; but unlike fission, fusion doesn’t use fissile materials as fuels, and it doesn’t generate long-lived nuclear fuel waste that must be managed. As a result, the regulatory requirements for FPPs will be very different from the regulations for today’s fission power plants — but precisely how they will differ is unclear. Likewise, the future public perception and social acceptance of each of these technologies cannot be projected, but could have a major influence on what generation technologies are used to meet future demand.The results of the study convey several messages about the future of fusion. For example, it’s clear that regulation can be a potentially large cost driver. This should motivate fusion companies to minimize their regulatory and environmental footprint with respect to fuels and activated materials. It should also encourage governments to adopt appropriate and effective regulatory policies to maximize their ability to use fusion energy in achieving their decarbonization goals. And for companies developing fusion technologies, the study’s message is clearly stated in the report: “If the cost and performance targets identified in this report can be achieved, our analysis shows that fusion energy can play a major role in meeting future electricity needs and achieving global net-zero carbon goals.” More

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      MIT Energy and Climate Club mobilizes future leaders to address global climate issues

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      One of MIT’s missions is helping to solve the world’s greatest problems — with a large focus on one of the most pressing topics facing the world today, climate change.The MIT Energy and Climate Club, (MITEC) formerly known as the MIT Energy Club, has been working since 2004 to inform and educate the entire MIT community about this urgent issue and other related matters.MITEC, one of the largest clubs on campus, has hundreds of active members from every major, including both undergraduate and graduate students. With a broad reach across the Institute, MITEC is the hub for thought leadership and relationship-building across campus.The club’s co-presidents Laurențiu Anton, doctoral candidate in electrical engineering and computer science; Rosie Keller, an MBA student in the MIT Sloan School of Management; and Thomas Lee, doctoral candidate in the Institute for Data, Systems, and Society, say that faculty, staff, and alumni are also welcome to join and interact with the continuously growing club.While they closely collaborate on all aspects of the club, each of the co-presidents has a focus area to support the student managing directors and vice presidents for several of the club’s committees. Keller oversees the External Relations, Social, Launchpad, and Energy and Climate Hackathon leadership teams. Lee supports the leadership team for next spring’s Energy Conference. He also assists the club treasurer on budget and finance and guides the industry Sponsorships team. Anton oversees marketing, community and education as well as the Energy and Climate Night and Energy and Climate Career Fair leadership teams.“We think of MITEC as the umbrella of all things related to energy and climate on campus. Our goal is to share actionable information and not just have discussions. We work with other organizations on campus, including the MIT Environmental Solutions Initiative, to bring awareness,” says Anton. “Our Community and Education team is currently working with the MIT ESI [Environmental Solutions Initiative] to create an ecosystem map that we’re excited to produce for the MIT community.”To share their knowledge and get more people interested in solving climate and energy problems, each year MITEC hosts a variety of events including the MIT Energy and Climate Night, the MIT Energy and Climate Hack, the MIT Energy and Climate Career Fair, and the MIT Energy Conference to be held next spring March 3-4. The club also offers students the opportunity to gain valuable work experience while engaging with top companies, such as Constellation Energy and GE Vernova, on real climate and energy issues through their Launchpad Program.Founded in 2006, the annual MIT Energy Conference is the largest student-run conference in North America focused on energy and climate issues, where hundreds of participants gather every year with the CEOs, policymakers, investors, and scholars at the forefront of the global energy transition.“The 2025 MIT Energy Conference’s theme is ‘Breakthrough to Deployment: Driving Climate Innovation to Market’ — which focuses on the importance of both cutting-edge research innovation as well as large-scale commercial deployment to successfully reach climate goals,” says Lee.Anton notes that the first of four MITEC flagship events the MIT Energy and Climate Night. This research symposium that takes place every year in the fall at the MIT Museum will be held on Nov. 8. The club invites a select number of keynote speakers and several dozen student posters. Guests are allowed to walk around and engage with students, and in return students get practice showcasing their research. The club’s career fair will take place in the spring semester, shortly after Independent Activities Period.MITEC also provides members opportunities to meet with companies that are working to improve the energy sector, which helps to slow down, as well as adapt to, the effects of climate change.“We recently went to Provincetown and toured Eversource’s battery energy storage facility. This helped open doors for club members,” says Keller. “The Provincetown battery helps address grid reliability problems after extreme storms on Cape Cod — which speaks to energy’s connection to both the mitigation and adaptation aspects of climate change,” adds Lee.“MITEC is also a great way to meet other students at MIT that you might not otherwise have a chance to,” says Keller.“We’d always welcome more undergraduate students to join MITEC. There are lots of leadership opportunities within the club for them to take advantage of and build their resumes. We also have good and growing collaboration between different centers on campus such as the Sloan Sustainability Initiative and the MIT Energy Initiative. They support us with resources, introductions, and help amplify what we’re doing. But students are the drivers of the club and set the agendas,” says Lee.All three co-presidents are excited to hear that MIT President Sally Kornbluth wants to bring climate change solutions to the next level, and that she recently launched The Climate Project at MIT to kick off the Institute’s major new effort to accelerate and scale up climate change solutions.“We look forward to connecting with the new directors of the Climate Project at MIT and Interim Vice President for Climate Change Richard Lester in the near future. We are eager to explore how MITEC can support and collaborate with the Climate Project at MIT,” says Anton.Lee, Keller, and Anton want MITEC to continue fostering solutions to climate issues. They emphasized that while individual actions like bringing your own thermos, using public transportation, or recycling are necessary, there’s a bigger picture to consider. They encourage the MIT community to think critically about the infrastructure and extensive supply chains behind the products everyone uses daily.“It’s not just about bringing a thermos; it’s also understanding the life cycle of that thermos, from production to disposal, and how our everyday choices are interconnected with global climate impacts,” says Anton.“Everyone should get involved with this worldwide problem. We’d like to see more people think about how they can use their careers for change. To think how they can navigate the type of role they can play — whether it’s in finance or on the technical side. I think exploring what that looks like as a career is also a really interesting way of thinking about how to get involved with the problem,” says Keller.“MITEC’s newsletter reaches more than 4,000 people. We’re grateful that so many people are interested in energy and climate change,” says Anton. More

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      Affordable high-tech windows for comfort and energy savings

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      Imagine if the windows of your home didn’t transmit heat. They’d keep the heat indoors in winter and outdoors on a hot summer’s day. Your heating and cooling bills would go down; your energy consumption and carbon emissions would drop; and you’d still be comfortable all year ’round.AeroShield, a startup spun out of MIT, is poised to start manufacturing such windows. Building operations make up 36 percent of global carbon dioxide emissions, and today’s windows are a major contributor to energy inefficiency in buildings. To improve building efficiency, AeroShield has developed a window technology that promises to reduce heat loss by up to 65 percent, significantly reducing energy use and carbon emissions in buildings, and the company just announced the opening of a new facility to manufacture its breakthrough energy-efficient windows.“Our mission is to decarbonize the built environment,” says Elise Strobach SM ’17, PhD ’20, co-founder and CEO of AeroShield. “The availability of affordable, thermally insulating windows will help us achieve that goal while also reducing homeowner’s heating and cooling bills.” According to the U.S. Department of Energy, for most homeowners, 30 percent of that bill results from window inefficiencies.Technology development at MITResearch on AeroShield’s window technology began a decade ago in the MIT lab of Evelyn Wang, Ford Professor of Engineering, now on leave to serve as director of the Advanced Research Projects Agency-Energy (ARPA-E). In late 2014, the MIT team received funding from ARPA-E, and other sponsors followed, including the MIT Energy Initiative through the MIT Tata Center for Technology and Design in 2016.The work focused on aerogels, remarkable materials that are ultra-porous, lighter than a marshmallow, strong enough to support a brick, and an unparalleled barrier to heat flow. Aerogels were invented in the 1930s and used by NASA and others as thermal insulation. The team at MIT saw the potential for incorporating aerogel sheets into windows to keep heat from escaping or entering buildings. But there was one problem: Nobody had been able to make aerogels transparent.An aerogel is made of transparent, loosely connected nanoscale silica particles and is 95 percent air. But an aerogel sheet isn’t transparent because light traveling through it gets scattered by the silica particles.After five years of theoretical and experimental work, the MIT team determined that the key to transparency was having the silica particles both small and uniform in size. This allows light to pass directly through, so the aerogel becomes transparent. Indeed, as long as the particle size is small and uniform, increasing the thickness of an aerogel sheet to achieve greater thermal insulation won’t make it less clear.Teams in the MIT lab looked at various applications for their super-insulating, transparent aerogels. Some focused on improving solar thermal collectors by making the systems more efficient and less expensive. But to Strobach, increasing the thermal efficiency of windows looked especially promising and potentially significant as a means of reducing climate change.The researchers determined that aerogel sheets could be inserted into the gap in double-pane windows, making them more than twice as insulating. The windows could then be manufactured on existing production lines with minor changes, and the resulting windows would be affordable and as wide-ranging in style as the window options available today. Best of all, once purchased and installed, the windows would reduce electricity bills, energy use, and carbon emissions.The impact on energy use in buildings could be considerable. “If we only consider winter, windows in the United States lose enough energy to power over 50 million homes,” says Strobach. “That wasted energy generates about 350 million tons of carbon dioxide — more than is emitted by 76 million cars.” Super-insulating windows could help home and building owners reduce carbon dioxide emissions by gigatons while saving billions in heating and cooling costs.The AeroShield storyIn 2019, Strobach and her MIT colleagues — Aaron Baskerville-Bridges MBA ’20, SM ’20 and Kyle Wilke PhD ’19 — co-founded AeroShield to further develop and commercialize their aerogel-based technology for windows and other applications. And in the subsequent five years, their hard work has attracted attention, recently leading to two major accomplishments.In spring 2024, the company announced the opening of its new pilot manufacturing facility in Waltham, Massachusetts, where the team will be producing, testing, and certifying their first full-size windows and patio doors for initial product launch. The 12,000 square foot facility will significantly expand the company’s capabilities, with cutting-edge aerogel R&D labs, manufacturing equipment, assembly lines, and testing equipment. Says Strobach, “Our pilot facility will supply window and door manufacturers as we launch our first products and will also serve as our R&D headquarters as we develop the next generation of energy-efficient products using transparent aerogels.”Also in spring 2024, AeroShield received a $14.5 million award from ARPA-E’s “Seeding Critical Advances for Leading Energy technologies with Untapped Potential” (SCALEUP) program, which provides new funding to previous ARPA-E awardees that have “demonstrated a viable path to market.” That funding will enable the company to expand its production capacity to tens of thousands, or even hundreds of thousands, of units per year.Strobach also cites two less-obvious benefits of the SCALEUP award.First, the funding is enabling the company to move more quickly on the scale-up phase of their technology development. “We know from our fundamental studies and lab experiments that we can make large-area aerogel sheets that could go in an entry or patio door,” says Elise. “The SCALEUP award allows us to go straight for that vision. We don’t have to do all the incremental sizes of aerogels to prove that we can make a big one. The award provides capital for us to buy the big equipment to make the big aerogel.”Second, the SCALEUP award confirms the viability of the company to other potential investors and collaborators. Indeed, AeroShield recently announced $5 million of additional funding from existing investors Massachusetts Clean Energy Center and MassVentures, as well as new investor MassMutual Ventures. Strobach notes that the company now has investor, engineering, and customer partners.She stresses the importance of partners in achieving AeroShield’s mission. “We know that what we’ve got from a fundamental perspective can change the industry,” she says. “Now we want to go out and do it. With the right partners and at the right pace, we may actually be able to increase the energy efficiency of our buildings early enough to help make a real dent in climate change.” More

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      More durable metals for fusion power reactors

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      For many decades, nuclear fusion power has been viewed as the ultimate energy source. A fusion power plant could generate carbon-free energy at a scale needed to address climate change. And it could be fueled by deuterium recovered from an essentially endless source — seawater.Decades of work and billions of dollars in research funding have yielded many advances, but challenges remain. To Ju Li, the TEPCO Professor in Nuclear Science and Engineering and a professor of materials science and engineering at MIT, there are still two big challenges. The first is to build a fusion power plant that generates more energy than is put into it; in other words, it produces a net output of power. Researchers worldwide are making progress toward meeting that goal.The second challenge that Li cites sounds straightforward: “How do we get the heat out?” But understanding the problem and finding a solution are both far from obvious.Research in the MIT Energy Initiative (MITEI) includes development and testing of advanced materials that may help address those challenges, as well as many other challenges of the energy transition. MITEI has multiple corporate members that have been supporting MIT’s efforts to advance technologies required to harness fusion energy.The problem: An abundance of helium, a destructive forceKey to a fusion reactor is a superheated plasma — an ionized gas — that’s reacting inside a vacuum vessel. As light atoms in the plasma combine to form heavier ones, they release fast neutrons with high kinetic energy that shoot through the surrounding vacuum vessel into a coolant. During this process, those fast neutrons gradually lose their energy by causing radiation damage and generating heat. The heat that’s transferred to the coolant is eventually used to raise steam that drives an electricity-generating turbine.The problem is finding a material for the vacuum vessel that remains strong enough to keep the reacting plasma and the coolant apart, while allowing the fast neutrons to pass through to the coolant. If one considers only the damage due to neutrons knocking atoms out of position in the metal structure, the vacuum vessel should last a full decade. However, depending on what materials are used in the fabrication of the vacuum vessel, some projections indicate that the vacuum vessel will last only six to 12 months. Why is that? Today’s nuclear fission reactors also generate neutrons, and those reactors last far longer than a year.The difference is that fusion neutrons possess much higher kinetic energy than fission neutrons do, and as they penetrate the vacuum vessel walls, some of them interact with the nuclei of atoms in the structural material, giving off particles that rapidly turn into helium atoms. The result is hundreds of times more helium atoms than are present in a fission reactor. Those helium atoms look for somewhere to land — a place with low “embedding energy,” a measure that indicates how much energy it takes for a helium atom to be absorbed. As Li explains, “The helium atoms like to go to places with low helium embedding energy.” And in the metals used in fusion vacuum vessels, there are places with relatively low helium embedding energy — namely, naturally occurring openings called grain boundaries.Metals are made up of individual grains inside which atoms are lined up in an orderly fashion. Where the grains come together there are gaps where the atoms don’t line up as well. That open space has relatively low helium embedding energy, so the helium atoms congregate there. Worse still, helium atoms have a repellent interaction with other atoms, so the helium atoms basically push open the grain boundary. Over time, the opening grows into a continuous crack, and the vacuum vessel breaks.That congregation of helium atoms explains why the structure fails much sooner than expected based just on the number of helium atoms that are present. Li offers an analogy to illustrate. “Babylon is a city of a million people. But the claim is that 100 bad persons can destroy the whole city — if all those bad persons work at the city hall.” The solution? Give those bad persons other, more attractive places to go, ideally in their own villages.To Li, the problem and possible solution are the same in a fusion reactor. If many helium atoms go to the grain boundary at once, they can destroy the metal wall. The solution? Add a small amount of a material that has a helium embedding energy even lower than that of the grain boundary. And over the past two years, Li and his team have demonstrated — both theoretically and experimentally — that their diversionary tactic works. By adding nanoscale particles of a carefully selected second material to the metal wall, they’ve found they can keep the helium atoms that form from congregating in the structurally vulnerable grain boundaries in the metal.Looking for helium-absorbing compoundsTo test their idea, So Yeon Kim ScD ’23 of the Department of Materials Science and Engineering and Haowei Xu PhD ’23 of the Department of Nuclear Science and Engineering acquired a sample composed of two materials, or “phases,” one with a lower helium embedding energy than the other. They and their collaborators then implanted helium ions into the sample at a temperature similar to that in a fusion reactor and watched as bubbles of helium formed. Transmission electron microscope images confirmed that the helium bubbles occurred predominantly in the phase with the lower helium embedding energy. As Li notes, “All the damage is in that phase — evidence that it protected the phase with the higher embedding energy.”Having confirmed their approach, the researchers were ready to search for helium-absorbing compounds that would work well with iron, which is often the principal metal in vacuum vessel walls. “But calculating helium embedding energy for all sorts of different materials would be computationally demanding and expensive,” says Kim. “We wanted to find a metric that is easy to compute and a reliable indicator of helium embedding energy.”They found such a metric: the “atomic-scale free volume,” which is basically the maximum size of the internal vacant space available for helium atoms to potentially settle. “This is just the radius of the largest sphere that can fit into a given crystal structure,” explains Kim. “It is a simple calculation.” Examination of a series of possible helium-absorbing ceramic materials confirmed that atomic free volume correlates well with helium embedding energy. Moreover, many of the ceramics they investigated have higher free volume, thus lower embedding energy, than the grain boundaries do.However, in order to identify options for the nuclear fusion application, the screening needed to include some other factors. For example, in addition to the atomic free volume, a good second phase must be mechanically robust (able to sustain a load); it must not get very radioactive with neutron exposure; and it must be compatible — but not too cozy — with the surrounding metal, so it disperses well but does not dissolve into the metal. “We want to disperse the ceramic phase uniformly in the bulk metal to ensure that all grain boundary regions are close to the dispersed ceramic phase so it can provide protection to those regions,” says Li. “The two phases need to coexist, so the ceramic won’t either clump together or totally dissolve in the iron.”Using their analytical tools, Kim and Xu examined about 50,000 compounds and identified 750 potential candidates. Of those, a good option for inclusion in a vacuum vessel wall made mainly of iron was iron silicate.Experimental testingThe researchers were ready to examine samples in the lab. To make the composite material for proof-of-concept demonstrations, Kim and collaborators dispersed nanoscale particles of iron silicate into iron and implanted helium into that composite material. She took X-ray diffraction (XRD) images before and after implanting the helium and also computed the XRD patterns. The ratio between the implanted helium and the dispersed iron silicate was carefully controlled to allow a direct comparison between the experimental and computed XRD patterns. The measured XRD intensity changed with the helium implantation exactly as the calculations had predicted. “That agreement confirms that atomic helium is being stored within the bulk lattice of the iron silicate,” says Kim.To follow up, Kim directly counted the number of helium bubbles in the composite. In iron samples without the iron silicate added, grain boundaries were flanked by many helium bubbles. In contrast, in the iron samples with the iron silicate ceramic phase added, helium bubbles were spread throughout the material, with many fewer occurring along the grain boundaries. Thus, the iron silicate had provided sites with low helium-embedding energy that lured the helium atoms away from the grain boundaries, protecting those vulnerable openings and preventing cracks from opening up and causing the vacuum vessel to fail catastrophically.The researchers conclude that adding just 1 percent (by volume) of iron silicate to the iron walls of the vacuum vessel will cut the number of helium bubbles in half and also reduce their diameter by 20 percent — “and having a lot of small bubbles is OK if they’re not in the grain boundaries,” explains Li.Next stepsThus far, Li and his team have gone from computational studies of the problem and a possible solution to experimental demonstrations that confirm their approach. And they’re well on their way to commercial fabrication of components. “We’ve made powders that are compatible with existing commercial 3D printers and are preloaded with helium-absorbing ceramics,” says Li. The helium-absorbing nanoparticles are well dispersed and should provide sufficient helium uptake to protect the vulnerable grain boundaries in the structural metals of the vessel walls. While Li confirms that there’s more scientific and engineering work to be done, he, along with Alexander O’Brien PhD ’23 of the Department of Nuclear Science and Engineering and Kang Pyo So, a former postdoc in the same department, have already developed a startup company that’s ready to 3D print structural materials that can meet all the challenges faced by the vacuum vessel inside a fusion reactor.This research was supported by Eni S.p.A. through the MIT Energy Initiative. Additional support was provided by a Kwajeong Scholarship; the U.S. Department of Energy (DOE) Laboratory Directed Research and Development program at Idaho National Laboratory; U.S. DOE Lawrence Livermore National Laboratory; and Creative Materials Discovery Program through the National Research Foundation of Korea. More