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Revolutionizing Time With Cutting-Edge Laser Technology

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Sunday, March 17, 2024

A schematic of a laser going through an AOM, which sends sound waves into a silicon cavity. CreditKenna Hughes-Castleberry/Ye and Hall GroupsPioneering work in laser physics has laid the foundation for significant advancements in precision measurement, enabling the development of techniques that significantly reduce residual amplitude modulation.Within atomic and laser physics communities, scientist John “Jan” Hall is a key figure in the history of laser frequency stabilization and precision measurement using lasers. Hall’s work revolved around understanding and manipulating stable lasers in ways that were revolutionary for their time. His work laid a technical foundation for measuring a tiny fractional distance change brought by a passing gravitational wave. His work in laser arrays awarded him the Nobel Prize in Physics in 2005.Building on this foundation, JILA and NIST Fellow Jun Ye and his team embarked on an ambitious journey to push the boundaries of precision measurement even further. This time, their focus turned to a specialized technique known as the Pound-Drever-Hall (PDH) method (developed by scientists R. V. Pound, Ronald Drever, and Jan Hall himself), which plays a large role in precision optical interferometry and laser frequency stabilization. While physicists have used the PDH method for decades in ensuring their laser frequency is stably “locked” to an artificial or quantum reference, a limitation arising from the frequency modulation process itself, called residual amplitude modulation (RAM), can still affect the stability and accuracy of the laser’s measurements.In a new Optica paper, Ye’s team, working with JILA electronic staff member Ivan Ryger and Hall, describe implementing a new approach for the PDH method, reducing RAM to never-before-seen minimal levels while simultaneously making the system more robust and simpler.As the PDH technique is implemented in various experiments, from gravitational wave interferometers to optical clocks, improving it further offers advancements to a range of scientific fields.A Dive Into Laser “Locking”Since its publication in 1983, the PDH method has been cited and utilized thousands of times. “Setting up a PDH lock is something you might learn in an undergraduate lab course; that’s just how central it is doing all the experiments we do in atomic physics,” explained recent Ph.D. graduate Dhruv Kedar, the paper’s co-first author.The PDH method uses a frequency modulation approach to precisely measure the laser frequency or phase fluctuations. The frequency modulation adds special “sidebands” (additional light signals) around a main light beam, known as the “carrier.” Comparison of these sidebands against the main carrier helps measure any slight changes in the frequency, or phase, of the main light beam relative to a reference. This technique is especially useful because it’s very sensitive and can reduce unwanted noise and errors.Physicists can then use these combined light beams to interrogate different environments, such as an optical cavity made of mirrors. To do this, the researchers must “lock” the laser to the cavity, that is, have the laser probe the cavity at a particular frequency.“What that means is that you’re trying to lock your laser to the center of your resonance,” Kedar added. This allows the laser to reach state-of-the-art levels of stability, which is especially important when trying to tease out tiny changes in the optical length or when monitoring quantum dynamics, such as energy shifts or spin changes in atoms and molecules.Unfortunately, “locking” a laser doesn’t always mean it stays stable or “in resonance with the center of the optical cavity, as noise like RAM can change the relative offsets of the reference light beams and introduces frequency shift,” co-first author and JILA Postdoc Zhibin Yao elaborated. “The RAM can contaminate your PDH error signal.”As the JILA researchers quickly realized, along with the rest of the laser physics community, reducing this RAM is crucial for improving the stability of the PDH technique and, in turn, their laser measurements. Overcoming the RAM problem has been a long struggle, but the new approach would make the fight much easier.Reducing RAM via EOMs and AOMsThe two-reference-light “sidebands” are essential for the PDH locking method. To generate the ‘sidebands,’ the JILA researchers needed to use a frequency modulator, either an electro-optic modulator (EOM) or an acousto-optic modulator (AOM).Historically, EOMs have been employed in various optical systems by applying electric fields to optical crystals to change the phase of laser light coming through the crystal. When an electric field is applied to certain types of crystals, it modulates the laser phase by altering the crystal’s refractive index. This process allows EOMs to add sidebands to the carrier beam easily.However, the effective phase modulation of the crystal used in EOMs is easily altered by environmental fluctuations, introducing RAM into the PDH error signal and, consequently, making it less stable. In contexts where ultra-high precision is required, such as running an optical timescale or operating an atomic clock, even minuscule amounts of RAM can introduce fluctuations at undesired levels.“EOMs add sidebands to the carrier laser in the optical domain, which is more challenging for us to control,” Kedar explained. “So instead, we can try to generate these sidebands in the electronic domain and translate them to the optical by using an AOM.”AOMs represent a newer approach to reducing RAM by using sound waves to modulate the laser light. When a sound wave propagates through a crystal or a transparent medium, it creates a diffraction pattern that bends the laser light in various amounts. As a light beam passes through this sound wave-altered medium, the variations in refractive index act like a series of tiny prisms, altering the path and, thus, the frequency of the light.Kedar added, “If you want to control the amplitude of each sideband, you control the amplitude of the main tone that you’re generating in the microwave domain via the AOM.” Because the AOM doesn’t modulate the laser frequency based on the electro-optic effect, it produces much less RAM noise than EOM, reducing the overall RAM level of the system. All of the beams coming out of the AOM crystal can be combined in a single optical fiber, and putting all frequency shift beams into a single, common spatial mode profile.Comparing EOM and AOMTo measure the advantages of this new PDH approach, Kedar, Yao, Ye, and the rest of the team ran an experiment using both the traditional EOM and their improved AOM setup and compared the results. They found that with the AOM, they could reduce the RAM levels from parts per million to a small fraction of parts per million. Equally important, this approach allows much more flexibility in controlling relative strength between the carrier and two sidebands. The AOM advantage is much more obvious when the carrier becomes vanishingly small.“Instead of parts per million, you can do like 0.2 parts per million, which seems like a small improvement, but that’s kind of toeing the line for acceptable levels of RAM for us,” Kedar elaborated. “Even though this RAM level is so small, it’s still a significant roadblock to improving our cavities and making them slightly better. That extra factor of two or three is enormously helpful in pushing the frontiers of state-of-the-art laser stabilization.”Expanding on the LegacyThe simple implementation of AOM instead of EOM suggests an answer even Hall would be proud of. “It’s simple enough that, in principle, someone can look at this scheme and see it as a natural method to interrogate a spectral feature,” Kedar elaborated. “In the end, this speaks to the research style that Jan and Jun both create: a very elegant, simple solution.”Reference: “Synthetic FM triplet for AM-free precision laser stabilization and spectroscopy” by John L. Hall, Dhruv Kedar, Ivan Ryger, Jun Ye and Zhibin Yao, 19 January 2024, Optica.DOI: doi:10.1364/OPTICA.507655

Pioneering work in laser physics has laid the foundation for significant advancements in precision measurement, enabling the development of techniques that significantly reduce residual amplitude...

Laser AOM Sound Waves Silicon Cavity Schematic

A schematic of a laser going through an AOM, which sends sound waves into a silicon cavity. Credit
Kenna Hughes-Castleberry/Ye and Hall Groups

Pioneering work in laser physics has laid the foundation for significant advancements in precision measurement, enabling the development of techniques that significantly reduce residual amplitude modulation.

Within atomic and laser physics communities, scientist John “Jan” Hall is a key figure in the history of laser frequency stabilization and precision measurement using lasers. Hall’s work revolved around understanding and manipulating stable lasers in ways that were revolutionary for their time. His work laid a technical foundation for measuring a tiny fractional distance change brought by a passing gravitational wave. His work in laser arrays awarded him the Nobel Prize in Physics in 2005.

Building on this foundation, JILA and NIST Fellow Jun Ye and his team embarked on an ambitious journey to push the boundaries of precision measurement even further. This time, their focus turned to a specialized technique known as the Pound-Drever-Hall (PDH) method (developed by scientists R. V. Pound, Ronald Drever, and Jan Hall himself), which plays a large role in precision optical interferometry and laser frequency stabilization.

While physicists have used the PDH method for decades in ensuring their laser frequency is stably “locked” to an artificial or quantum reference, a limitation arising from the frequency modulation process itself, called residual amplitude modulation (RAM), can still affect the stability and accuracy of the laser’s measurements.

In a new Optica paper, Ye’s team, working with JILA electronic staff member Ivan Ryger and Hall, describe implementing a new approach for the PDH method, reducing RAM to never-before-seen minimal levels while simultaneously making the system more robust and simpler.

As the PDH technique is implemented in various experiments, from gravitational wave interferometers to optical clocks, improving it further offers advancements to a range of scientific fields.

A Dive Into Laser “Locking”

Since its publication in 1983, the PDH method has been cited and utilized thousands of times. “Setting up a PDH lock is something you might learn in an undergraduate lab course; that’s just how central it is doing all the experiments we do in atomic physics,” explained recent Ph.D. graduate Dhruv Kedar, the paper’s co-first author.

The PDH method uses a frequency modulation approach to precisely measure the laser frequency or phase fluctuations. The frequency modulation adds special “sidebands” (additional light signals) around a main light beam, known as the “carrier.” Comparison of these sidebands against the main carrier helps measure any slight changes in the frequency, or phase, of the main light beam relative to a reference. This technique is especially useful because it’s very sensitive and can reduce unwanted noise and errors.

Physicists can then use these combined light beams to interrogate different environments, such as an optical cavity made of mirrors. To do this, the researchers must “lock” the laser to the cavity, that is, have the laser probe the cavity at a particular frequency.

“What that means is that you’re trying to lock your laser to the center of your resonance,” Kedar added. This allows the laser to reach state-of-the-art levels of stability, which is especially important when trying to tease out tiny changes in the optical length or when monitoring quantum dynamics, such as energy shifts or spin changes in atoms and molecules.

Unfortunately, “locking” a laser doesn’t always mean it stays stable or “in resonance with the center of the optical cavity, as noise like RAM can change the relative offsets of the reference light beams and introduces frequency shift,” co-first author and JILA Postdoc Zhibin Yao elaborated. “The RAM can contaminate your PDH error signal.”

As the JILA researchers quickly realized, along with the rest of the laser physics community, reducing this RAM is crucial for improving the stability of the PDH technique and, in turn, their laser measurements. Overcoming the RAM problem has been a long struggle, but the new approach would make the fight much easier.

Reducing RAM via EOMs and AOMs

The two-reference-light “sidebands” are essential for the PDH locking method. To generate the ‘sidebands,’ the JILA researchers needed to use a frequency modulator, either an electro-optic modulator (EOM) or an acousto-optic modulator (AOM).

Historically, EOMs have been employed in various optical systems by applying electric fields to optical crystals to change the phase of laser light coming through the crystal. When an electric field is applied to certain types of crystals, it modulates the laser phase by altering the crystal’s refractive index. This process allows EOMs to add sidebands to the carrier beam easily.

However, the effective phase modulation of the crystal used in EOMs is easily altered by environmental fluctuations, introducing RAM into the PDH error signal and, consequently, making it less stable. In contexts where ultra-high precision is required, such as running an optical timescale or operating an atomic clock, even minuscule amounts of RAM can introduce fluctuations at undesired levels.

“EOMs add sidebands to the carrier laser in the optical domain, which is more challenging for us to control,” Kedar explained. “So instead, we can try to generate these sidebands in the electronic domain and translate them to the optical by using an AOM.”

AOMs represent a newer approach to reducing RAM by using sound waves to modulate the laser light. When a sound wave propagates through a crystal or a transparent medium, it creates a diffraction pattern that bends the laser light in various amounts. As a light beam passes through this sound wave-altered medium, the variations in refractive index act like a series of tiny prisms, altering the path and, thus, the frequency of the light.

Kedar added, “If you want to control the amplitude of each sideband, you control the amplitude of the main tone that you’re generating in the microwave domain via the AOM.” Because the AOM doesn’t modulate the laser frequency based on the electro-optic effect, it produces much less RAM noise than EOM, reducing the overall RAM level of the system. All of the beams coming out of the AOM crystal can be combined in a single optical fiber, and putting all frequency shift beams into a single, common spatial mode profile.

Comparing EOM and AOM

To measure the advantages of this new PDH approach, Kedar, Yao, Ye, and the rest of the team ran an experiment using both the traditional EOM and their improved AOM setup and compared the results. They found that with the AOM, they could reduce the RAM levels from parts per million to a small fraction of parts per million. Equally important, this approach allows much more flexibility in controlling relative strength between the carrier and two sidebands. The AOM advantage is much more obvious when the carrier becomes vanishingly small.

“Instead of parts per million, you can do like 0.2 parts per million, which seems like a small improvement, but that’s kind of toeing the line for acceptable levels of RAM for us,” Kedar elaborated. “Even though this RAM level is so small, it’s still a significant roadblock to improving our cavities and making them slightly better. That extra factor of two or three is enormously helpful in pushing the frontiers of state-of-the-art laser stabilization.”

Expanding on the Legacy

The simple implementation of AOM instead of EOM suggests an answer even Hall would be proud of. “It’s simple enough that, in principle, someone can look at this scheme and see it as a natural method to interrogate a spectral feature,” Kedar elaborated. “In the end, this speaks to the research style that Jan and Jun both create: a very elegant, simple solution.”

Reference: “Synthetic FM triplet for AM-free precision laser stabilization and spectroscopy” by John L. Hall, Dhruv Kedar, Ivan Ryger, Jun Ye and Zhibin Yao, 19 January 2024, Optica.
DOI: doi:10.1364/OPTICA.507655

Read the full story here.
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The economic case for green steel production at a Michigan steel mill

Dearborn, Michigan, was at the heart of auto industry innovation during the days of the Model T Ford. Now clean energy and environmental justice advocates are proposing that the city play a lead role in greening the auto industry, through a transformation of the Dearborn Works steel mill to “green steel” — a…

Dearborn, Michigan, was at the heart of auto industry innovation during the days of the Model T Ford. Now clean energy and environmental justice advocates are proposing that the city play a lead role in greening the auto industry, through a transformation of the Dearborn Works steel mill to ​“green steel” — a steelmaking process powered by hydrogen and renewable energy with drastically lower emissions than a traditional blast furnace. The blast furnace at Dearborn Works is due for relining in 2027, at an estimated cost of $470 million. Advocates argue that instead of prolonging the blast furnace’s life, its owner, Cleveland Cliffs, should invest another $2 billion dollars and convert the mill to Direct Reduced Iron (DRI) technology powered by green hydrogen (hydrogen produced with renewable energy). An October report by Dr. Elizabeth Boatman of the firm 5 Lakes Energy examines the economics and logistics of such a conversion, and argues that demand for cleaner steel is likely to grow as auto companies and other global industries seek to lower their greenhouse gas footprints. Starting in 2026, steel importers to the European Union will need to make payments to offset emissions associated with steel production. Worldwide, the auto industry is the second largest consumer of steel after construction, and ​“being able to pass on the price of a ​‘green steel premium’ to its end consumers, the automotive industry is uniquely positioned to create demand for green steel without having to rely on public subsidies,” the European Union think tank CEPS said in a recent publication. “This is a great chance for the state to step in now and ensure this conversion happens, instead of waiting another 20 years,” said Boatman. ​“All the economic indicators suggest clean steel is the steel product of the future, and the best way to future-proof jobs especially in the steel sector and especially for unions.” Cutting pollution, creating jobs  Cleveland Cliffs is planning to convert its Middletown, Ohio, steel mill to DRI, tapping a $500 million federal grant for industrial decarbonization under the Bipartisan Infrastructure Law and Inflation Reduction Act. A DRI furnace does not need to use coke or heat iron ore to 3,000 degrees Fahrenheit to produce pure ​“pig iron”; the same result is achieved with a different chemical process at much lower temperatures. DRI furnaces can be powered by natural gas or clean hydrogen. Initially, Cleveland Cliffs says, its Middletown mill will run on natural gas, releasing about half the carbon emissions of its current blast furnace. Eventually, the company announced, it could switch to hydrogen. Along with slashing greenhouse gas emissions, a similar green steel conversion at Dearborn Works would greatly reduce the local air pollution burden facing residents in the heavily industrial area, which is also home to a Marathon oil refinery, a major rail yard, and other polluters. But it wouldn’t be cheap. Boatman’s report estimated the cost of converting a blast furnace to a DRI furnace and associated electric arc furnaces at $1.57 billion, plus $2.6 billion to build a green hydrogen plant. Utility DTE Energy would need to work with grid operator MISO to add about 2 GW of solar and 2 GW of wind power, plus battery storage, to the grid to power the green hydrogen production. The conversion would mean closure of the EES Coke plant, which turns coal into coke for the steel mill, on heavily polluted Zug Island in the River Rouge just outside Detroit, five miles from Dearborn. In 2022, the EPA sued the coke plant, a subsidiary of DTE Energy, over Clean Air Act violations. A recent study by the nonprofit Industrious Labs found that the EES Coke plant could be responsible for up to 57 premature deaths and more than 15,000 asthma attacks. The report also found that more than half the people living within a three-mile radius of both the steel mill and coke plant are low-income, and three-quarters of those living around the coke plant are people of color, as are half those living around the steel mill. “The total health costs are quite significant,” said Nick Leonard, executive director of the Great Lakes Environmental Law Center, which is representing local residents as intervenors in the EPA lawsuit against the coke plant. ​“We allow companies to externalize those costs and not account for them. If they were required by some sort of change in policy or regulation to be responsible for those costs, it would certainly make the case they could make this expensive switch” to green steel. The law center also represented residents in legal proceedings around Dearborn Works’ Clean Air Act violations, including a 2015 consent decree and a 2023 mandate to install a new electrostatic precipitator at a cost of $100 million. Leonard said local residents ​“know Cleveland Cliffs poses a risk to their health, and they want solutions. They know there’s a problem — they are frustrated by the lack of will or attention from state and local government.” Cleveland Cliffs did not respond to a request for comment. Why Michigan? The country’s active steel mills are concentrated in Pennsylvania, Indiana, Ohio, and Michigan. Advocates and residents are asking Nippon Steel to consider a green steel conversion at the Gary Works mill in Northwest Indiana, if the global corporation succeeds in acquiring Gary Works owner U.S. Steel. Advocates have also proposed green steel conversions for Pennsylvania mills.

Energy
Chemicals
Health

Ensuring a durable transition

Progress on the energy transition depends on collective action benefiting all stakeholders, agreed participants in MITEI’s annual research conference.

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.”

Energy
Business
Climate

Massachusetts passes bill to speed clean energy and slow gas expansion

Yesterday, Massachusetts lawmakers made major moves to reduce greenhouse gas emissions and transition the state to clean energy. Legislators approved a long-awaited climate bill that will limit gas pipeline expansion, make it easier to site and build renewables, and allow utilities to use geothermal energy — instead…

Yesterday, Massachusetts lawmakers made major moves to reduce greenhouse gas emissions and transition the state to clean energy. Legislators approved a long-awaited climate bill that will limit gas pipeline expansion, make it easier to site and build renewables, and allow utilities to use geothermal energy — instead of fossil fuels — to heat and cool homes. Governor Maura Healey, a Democrat, is expected to sign it into law in the coming days. The bill first passed the Senate over the summer but stalled in the House, where representatives wanted a more narrow focus that didn’t include gas system reforms. The legislators managed to reach a compromise, and environmental advocates are pleased with the result. “The Legislature and the Healey-Driscoll Administration are taking tangible steps to drive the Commonwealth’s clean energy future forward in the wake of the federal Election outcome,” the Acadia Center said in a press release following the vote. Massachusetts is the first state to take action on climate since Trump’s re-election; the new federal landscape could spur more state lawmakers to try and advance climate legislation. A large portion of the new bill streamlines the steps for clean energy projects to get off the ground. Instead of having to go through multiple agencies for approval, the Energy Facilities Siting Board will oversee the entire process. ​“We’re eliminating a lot of the friction that prevents projects from being built,” said Caitlin Peale Sloan, vice president of the Massachusetts chapter at Conservation Law Foundation. “This will hopefully unlock the clean energy that we need to get built,” Sloan said. Massachusetts has committed to reaching net-zero emissions by 2050 and cutting emissions 50 percent below 1990 levels by 2030. A faster permitting process could leave less room for opposition from impacted communities. On top of that, the bill places a time limit on challenges to renewable energy projects — which can sometimes hold up construction for years — to 15 months. But to protect already burdened communities, the legislature added a requirement that each project proposal must look at cumulative environmental impact, or how a new facility could add to the existing pollution in a given area. The bill also sets state targets for long duration energy storage and allows contracts for offshore wind and battery storage for up to 30 years, instead of the current 20. One provision allows Massachusetts to receive nuclear energy from neighboring Connecticut; in exchange, Connecticut is expected to agree to take wind power from MA’s 1,200 megawatt Vineyard Wind 2 project. In terms of gas reform, the new law takes an important step by changing how gas companies are defined. Until now, gas utilities in Massachusetts have only been allowed to deliver gas to their customers, and no alternative fuels. Going forward, they can provide heating and cooling to homes through networked geothermal energy, which connects water-filled pipes in the street to heat pumps in buildings. Several utilities are already operating small-scale demonstration projects of this technology in the state. In June, Eversource Gas brought the first networked geothermal pilot online, delivering energy to 36 buildings in Framingham, MA.

Energy
Climate
Pollution

3 Questions: Can we secure a sustainable supply of nickel?

Extraction of nickel, an essential component of clean energy technologies, needs stronger policies to protect local environments and communities, MIT researchers say.

As the world strives to cut back on carbon emissions, demand for minerals and metals needed for clean energy technologies is growing rapidly, sometimes straining existing supply chains and harming local environments. In a new study published today in Joule, Elsa Olivetti, a professor of materials science and engineering and director of the Decarbonizing Energy and Industry mission within MIT’s Climate Project, along with recent graduates Basuhi Ravi PhD ’23 and Karan Bhuwalka PhD ’24 and nine others, examine the case of nickel, which is an essential element for some electric vehicle batteries and parts of some solar panels and wind turbines.How robust is the supply of this vital metal, and what are the implications of its extraction for the local environments, economies, and communities in the places where it is mined? MIT News asked Olivetti, Ravi, and Bhuwalka to explain their findings.Q: Why is nickel becoming more important in the clean energy economy, and what are some of the potential issues in its supply chain?Olivetti: Nickel is increasingly important for its role in EV batteries, as well as other technologies such as wind and solar. For batteries, high-purity nickel sulfate is a key input to the cathodes of EV batteries, which enables high energy density in batteries and increased driving range for EVs. As the world transitions away from fossil fuels, the demand for EVs, and consequently for nickel, has increased dramatically and is projected to continue to do so.The nickel supply chain for battery-grade nickel sulfate includes mining nickel from ore deposits, processing it to a suitable nickel intermediary, and refining it to nickel sulfate. The potential issues in the supply chain can be broadly described as land use concerns in the mining stage, and emissions concerns in the processing stage. This is obviously oversimplified, but as a basic structure for our inquiry we thought about it this way. Nickel mining is land-intensive, leading to deforestation, displacement of communities, and potential contamination of soil and water resources from mining waste. In the processing step, the use of fossil fuels leads to direct emissions including particulate matter and sulfur oxides. In addition, some emerging processing pathways are particularly energy-intensive, which can double the carbon footprint of nickel-rich batteries compared to the current average.Q: What is Indonesia’s role in the global nickel supply, and what are the consequences of nickel extraction there and in other major supply countries?Ravi: Indonesia plays a critical role in nickel supply, holding the world's largest nickel reserves and supplying nearly half of the globally mined nickel in 2023. The country's nickel production has seen a remarkable tenfold increase since 2016. This production surge has fueled economic growth in some regions, but also brought notable environmental and social impacts to nickel mining and processing areas.Nickel mining expansion in Indonesia has been linked to health impacts due to air pollution in the islands where nickel processing is prominent, as well as deforestation in some of the most biodiversity-rich locations on the planet. Reports of displacement of indigenous communities, land grabbing, water rights issues, and inadequate job quality in and around mines further highlight the social concerns and unequal distribution of burdens and benefits in Indonesia. Similar concerns exist in other major nickel-producing countries, where mining activities can negatively impact the environment, disrupt livelihoods, and exacerbate inequalities.On a global scale, Indonesia’s reliance on coal-based energy for nickel processing, particularly in energy-intensive smelting and leaching of a clay-like material called laterite, results in a high carbon intensity for nickel produced in the region, compared to other major producing regions such as Australia.Q: What role can industry and policymakers play in helping to meet growing demand while improving environmental safety?Bhuwalka: In consuming countries, policies can foster “discerning demand,” which means creating incentives for companies to source nickel from producers that prioritize sustainability. This can be achieved through regulations that establish acceptable environmental footprints for imported materials, such as limits on carbon emissions from nickel production. For example, the EU’s Critical Raw Materials Act and the U.S. Inflation Reduction Act could be leveraged to promote responsible sourcing. Additionally, governments can use their purchasing power to favor sustainably produced nickel in public procurement, which could influence industry practices and encourage the adoption of sustainability standards.On the supply side, nickel-producing countries like Indonesia can implement policies to mitigate the adverse environmental and social impacts of nickel extraction. This includes strengthening environmental regulations and enforcement to reduce the footprint of mining and processing, potentially through stricter pollution limits and responsible mine waste management. In addition, supporting community engagement, implementing benefit-sharing mechanisms, and investing in cleaner nickel processing technologies are also crucial.Internationally, harmonizing sustainability standards and facilitating capacity building and technology transfer between developed and developing countries can create a level playing field and prevent unsustainable practices. Responsible investment practices by international financial institutions, favoring projects that meet high environmental and social standards, can also contribute to a stable and sustainable nickel supply chain.

Energy
Sustainable
Forests

The Department of Energy wants to pay companies to make greener solar panels

Only six panels on the market meet the government's sustainability standards — but that number could soon grow.

In June, U.S. solar manufacturer Qcells became the second company in the world to register its solar panels with EPEAT, a labeling system that sets sustainability standards for electronics makers. By doing so, the company triggered an obscure regulation that requires federal agencies to purchase EPEAT-certified solar panels. If, say, NASA wants to build a solar farm to power a research facility, it must now purchase panels that meet EPEAT’s strict sustainability requirements — including a first-of-its-kind limit on the carbon emissions tied to solar manufacturing. There’s just one problem: Although EPEAT launched its solar standards in 2019, as of today, there are only six EPEAT-registered solar panels on the global market. And there are currently no EPEAT-registered solar inverters, devices that convert the direct current electricity a solar panel produces to alternating current electricity, which the grid uses. That doesn’t leave a lot of choices for the federal government, or anyone else who wants to purchase sustainably-produced solar equipment. That’s why, in October, the Department of Energy, or DOE, launched a new prize that offers up to $450,000 to U.S.-based solar panel and inverter manufacturers that achieve EPEAT certification for their products. As a new wave of domestic solar manufacturing kicks into high gear, the DOE hopes the prize will ensure that companies use efficient processes, sustainable materials, fair labor practices, and low-carbon energy. “The fact of the matter is, not all solar [products] in their production are created equal,” said Patty Dillon, a vice president at the Global Electronics Council, the sustainable technology nonprofit that manages the EPEAT ecolabel. Solar panels convert the sun’s rays into electricity in a process that emits no greenhouse gases, which makes them essential for fighting climate change. To achieve net-zero emissions by 2050, the International Energy Agency estimates that the world must add 630 gigawatts of new solar power annually by 2030 — up from the 135 gigawatts installed in 2020.  But some solar panels are more climate-friendly than others. Polysilicon, which is used to make the sunlight-harvesting cells inside silicon panels, is made using an energy-intensive process often powered by fossil fuels. The frames that hold solar panels together are made of aluminum, which is typically smelted in China using coal-powered electricity. The manufacturing processes that turn these materials into a solar panel also require energy, which can lead to more emissions. On a global level, the difference between solar panels manufactured using clean energy and those made with fossil fuels could amount to tens of billions of metric tons of carbon pollution by the middle of the 21st century. Workers process aluminum alloy frames for solar panels in Hai’an, China. CFOTO / Future Publishing via Getty Images To minimize those emissions, along with other environmental challenges like the use of toxic chemicals and the disposal of solar e-waste, companies must take a hard look at their supply chains and, in some cases, engage in difficult clean-up work. The DOE’s new prize, “Promoting Registration of Inverters and Modules with Ecolabel,” or PRIME, encourages companies to do so by going through the EPEAT registration process. “EPEAT certification enables companies to show how they have been taking the steps to have more environmentally friendly supply chains and manufacturing processes,” Becca Jones-Albertus, who directs the DOE’s solar energy technologies office, told Grist.  Solar companies seeking EPEAT registration must meet a list of criteria that span four broad themes: climate change, sustainable resource use, hazardous chemicals, and responsible supply chains. Depending on how many standards a manufacturer meets, it can receive an EPEAT Bronze, Silver, or Gold designation.  In addition, as of June, solar manufacturers registered with EPEAT are required to meet the industry’s first-ever criteria for embodied carbon, the emissions generated when a product is produced. For each kilowatt of power produced, no more than 630 kilograms of CO2 can be emitted during the production of an EPEAT-registered solar panel. The limit, Dillon says, represents about 25 percent fewer carbon emissions than the global average. Solar panels that fall below the “ultra low carbon” threshold of 400 kilograms of CO2 per kilowatt of power earn a special EPEAT Climate+ designation.  “That basically represents the best in class,” Dillon said. It’s difficult to make a direct comparison to fossil fuel plants, since most of their emissions come from operations rather than building infrastructure. But other research has found that over their lifespan, solar plants are considerably more climate friendly, emitting roughly 50 grams of CO2 per kilowatt-hour of energy produced compared with about 1,000 grams per kilowatt-hour for coal.  Meeting EPEAT’s requirements isn’t easy, which might explain why there are only two companies — QCells and the Arizona-based First Solar — currently listed on the registry. And only two solar panels manufactured by First Solar have earned the ecolabel’s Climate+ badge. QCells, which manufactures two EPEAT-registered panels at a factory in Dalton, Georgia, spent about two years going through a “very extensive” certification process that involved collecting data across its supply chain and submitting to a third-party audit, corporate communications lead Debra DeShong told Grist. Arrays of solar cells on conveyor belt at Qcells’ facility in Dalton, Georgia. Dustin Chambers for The Washington Post via Getty Images “It’s not an easy task,” DeShong said. “It requires resources and it requires a will.” Other companies may now be motivated to try. QCells’ additions to the EPEAT registry in June activated the Federal Acquisition Regulation, which requires the federal government to purchase goods that meet standards set by the U.S. Environmental Protection Agency, except in limited circumstances where it’s impractical to do so. In the case of solar panels, that means EPEAT-registered products. The DOE’s PRIME Prize, which provides U.S. solar manufacturers $50,000 for starting the registration process and up to $100,000 per product for up to four products that complete it, offers additional incentive. Jones-Albertus told Grist that the prize was designed to “roughly offset the cost of collecting all the data and moving through the registration process.” Solar companies “told us that they’re interested in EPEAT certification, but they haven’t gotten there yet,” Jones-Albertus said. “We’re hoping to provide incentives so that companies go through the EPEAT registration process sooner.” Companies peering deep into their supply chains for the first time might discover they have to make some changes to meet EPEAT registration requirements. To slim down the carbon footprint of its panels, a solar manufacturer might have to switch to a low-carbon polysilicon supplier. (QCells, for instance, is purchasing polysilicon from a facility in Washington state that produces the stuff using hydropower.) Or it might decide to swap out virgin aluminum frames manufactured overseas for recycled steel ones built domestically by Origami Solar, a change that can reduce carbon emissions tied to the frame by upwards of 90 percent. To meet EPEAT’s optional recycled content criteria, a manufacturer could decide to start purchasing recycled panel glass from a company like SolarCycle.  Making these sorts of manufacturing supply chain alterations takes time and money beyond what the new DOE prize will provide. But Dillon, of the Global Electronics Council, is optimistic that more companies will start registering their products with EPEAT now that federal purchasers require it. Erik Petersen, the chief strategy officer at Origami Solar, believes the Biden administration’s push for clean domestic manufacturing, combined with growing consumer interest in supply chain transparency, will spur more U.S. solar companies to ensure their products meet high sustainability standards.   “What’s exciting is all of these forces are coming together at the same time,” Petersen told Grist. “That really gives the industry an incentive to do the right things.” This story was originally published by Grist with the headline The Department of Energy wants to pay companies to make greener solar panels on Nov 1, 2024.

Energy
Government
Climate

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