It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Friday, November 15, 2024
Decline in West African coastal fish stocks threatens food security and livelihoods
A new ICTA-UAB study integrates different knowledge systems for the assessment of fish stock conditions and historical performance
Fish stocks along the West African coast have declined significantly over the past five decades, threatening food security and the livelihoods of the fishing communities that depend on them, according to a study by the Institute of Environmental Science and Technology of the Universitat Autònoma de Barcelona (ICTA-UAB) in collaboration with Fundação Maio Biodiversidade (FMB).
Small-scale fisheries play a vital role in providing food and livelihoods for millions of people around the world, particularly in low-income countries in Africa. However, there is limited statistical data on the composition, abundance, and distribution of the fisheries’ resources, which is crucial for effective management.
New research, recently published in the journal Marine Policy, documents changes in the catches of small-scale fisheries, highlighting a significant decline not only in volume of catches, but also in the size of fish for key local species.
Scientists compiled official catch landing data and combined it with local ecological knowledge from local fishermen and fishmongers on Maio island, in Cabo Verde, designated a UNESCO Biosphere Reserve since 2020.
“Monitoring of fish landings in West African countries is limited and under-represents catches at the local level, especially from artisanal fisheries, creating data gaps that hinder effective management,” says Thais Peixoto Macedo, ICTA-UAB researcher and lead author of the study, who explains that traditional fishers' accounts revealed trends that are poorly captured in official records. “The findings in this area show us trends that are likely to occur on other islands of the archipelago or other West African coastal areas and should be taken into account in marine resource management plans.”
Local communities believe that certain fishing practices, such as spearfishing with scuba gear and semi-industrial fishing with purse seines and night lights, are major contributors to the decline of fish stocks. In the case of semi-industrial fishing, they report that vessels fish within the three-nautical-mile zone and in marine protected areas reserved for artisanal fishing.
The most reported depleted species include groupers (dusky grouper, island grouper and the African hind) and small pelagic fish such as mackerel and bigeye scad. “According to local fishermen, the decline of small pelagic fish due to semi-industrial coastal fishing is negatively affecting artisanal catches of large pelagic species, such as yellowfin tuna and albacore, an important commercial species for local and international markets”, says Benalsy Varela, FMB staff who contributed to the study. Spiny and slipper lobsters, particularly targeted to supply more tourist-intensive islands, were also considered depleted.
The research highlights a phenomenon known as “Shifting Baseline Syndrome”, where people gradually adjust their perception of what is healthy or natural to a new reality, forgetting past conditions and accepting it as the 'new normal'. Younger fishermen reported smaller catches and fish sizes than older generations, but a larger proportion of the younger group believe that fish stocks are not in decline.
Scientists have found a trigger for social learning in wild animals. An experiment on great tits has pinpointed a single factor—immigration—that can cause birds to pay close attention to others, leading them to rapidly adopt useful behaviors. The study is the first to provide experimental support of a long-held assumption that immigrants should strategically use social learning. The study, conducted by scientists from the Max Planck Institute of Animal Behavior (MPI-AB) and the Cluster of Excellence Collective Behaviour at the University of Konstanz in Germany, is published November 14 in PLOS Biology.
Many animals that live in groups learn from one another, but few wild animals have opened a window into understanding animal social learning like a single bird species: the great tits. Great tits flew to fame in the 1920s after birds started opening the foil lids of milk bottles to feed on the cream within. Residents of a small town in England were the first to report the behavior, but soon people across Europe were opening their doors to find that their milk bottles had been raided by birds. The behavior spread so far so quickly that scientists considered it unlikely that individual birds across a continent were inventing this trick on their own. Could the birds be learning from each other?
The answer remained hidden until 2015 when a team led by Lucy Aplin, then at the University of Oxford, conducted an experiment on a population of great tits in an English forest. Her experiment showed that birds were able to learn how to liberate food from a puzzle box by copying the solution from others—confirming that the original milk-raiding birds had also been passing on their thieving ways to their flock.
“Social learning is a great shortcut when it comes to safely testing new waters,” says Chimento, a postdoctoral researcher who worked in Aplin’s team at the MPI-AB. “Paying attention to what others are doing gives you the chance to see whether a new behavior is beneficial, or potentially dangerous. Copying it means that you too can reap the reward.”
By copying the behaviors of others, animals can potentially unlock resources. So Chimento and Aplin wanted to know if there was an ingredient that would catalyze social learning, allowing animals to more efficiently realize its rewards. According to theory, there was a possibility: “Theoretical models have suggested that animals should change their social learning strategy when faced with new environments,” says Chimento who is now at the Cluster of Excellence Collective Behaviour at the University of Konstanz. In other words, when animals move into a new place, they might learn more from others. “But nobody has experimentally shown this in non-human animals,” he says.
Using an automated puzzle box system they developed, the team designed an experiment to test this immigration hypothesis. They created experimental social groups of wild-caught great tits. Each group was provided a tutor which was trained to access food from a puzzle box by either pushing the door left or right. One tutor was then released into each group, so that their flock mates learned to prefer using one solution over another.
Next came the immigration event. Right-pushing birds were transferred into aviaries where resident birds were using the left-hand solution, and vice versa. Not only did immigrants see that residents were opening the puzzle box in a new way, but in some groups, the newcomers also discovered that residents scored a superior reward by doing so.
“What’s important is that the immigrants were blind to the fact that the food reward had changed,” said Chimento, the study’s lead author. “Immigrants could only know something changed by either watching the residents use the puzzle, or by trying the other side themselves.”
And watch, the immigrants did. After being released into the new aviary, the vast majority of immigrants—80 percent—switched their method immediately. Instead of attempting the method they had been trained on, the immigrants used the resident solution on their first try. Chimento says that this stark result makes a compelling case that social learning was at play: “Of course we can’t ask the birds exactly where they were getting their information from, but these behavioral patterns are striking enough to suggest that the birds were watching residents very closely from the moment they entered their new social group.”
But there was an extra twist. These immigrants were not just moved to a place where residents were getting better food; their visual world was also drastically transformed. The scientists manipulated the environment of immigrants by changing the foliage in the experimental aviaries as well.
And it was the altered visual environment that proved to be the linchpin for learning. In trials where the foliage was not changed, only 25 percent of the newcomers tried the resident solution on the first attempt, even when locals were earning better food. “They didn’t necessarily ignore the residents, but they took much longer to all switch over to the more rewarding solution. Our analyses suggested this was because they weren’t as influenced by the residents” Chimento says.
This is the first experimental evidence to show the powerful impact that immigration has on how animals learn from each other. And in the real world, this can be profound.
Says Aplin, the study’s senior author: “In nature, animals are often moving from one environment to another, so it’s helpful to have a strategy to weed out what are good and bad behaviors to use in the new place.” That’s why the theory predicted that different learning strategies should evolve to act as a filter when animals enter new environments. “Our study provided the experimental evidence to show that this is also what happens in real life,” she says.
Immigrant birds learn from socially observed differences in payoffs when their environment changes
Article Publication Date
14-Nov-2024
Emerging alternatives to reduce animal testing show promise
Summary author: Walter Beckwith
American Association for the Advancement of Science (AAAS)
In a Policy Forum, Chad Nelson and colleagues highlight the efforts of the U.S. Food and Drug Administration (FDA) in advancing alternative methods to reduce animal testing for regulatory use. Animal studies have been crucial for advancing disease understanding, developing therapies, and assessing the safety and effectiveness of consumer products. However, reducing animal use and developing effective alternatives is an ongoing priority. Although advances in biology, engineering, and artificial intelligence offer new opportunities to improve product safety assessments, these technologies require extensive development to meet regulatory standards. According to Nelson et al., the FDA is working to advance alternative methods – new approach methodologies (NAMs) – that improve the safety, risk, and efficacy understanding of regulated products while reducing animal use. Here, the authors highlight these efforts. Over the years, the FDA has advanced NAMs, such as in vitro ocular irritation tests, which have replaced traditional rabbit testing. The FDA has also advanced the use of computational models to assess drug safety. Additionally, the agency has developed qualification programs to evaluate and validate these alternative methods for regulatory use, ensuring their effectiveness in making regulatory decisions. The FDA encourages innovation through programs like ISTAND, which supports new tools like organ-on-a-chip technologies. Nelson et al. argue that by collaborating with stakeholders, hosting workshops, and conducting its own research, the FDA continues to lead efforts in validating and adopting alternative methods that reduce reliance on animal testing.
Advancing alternative methods to reduce animal testing
Article Publication Date
15-Nov-2024
Industrial snow: Factories trigger local snowfall by freezing clouds
Estonian Research Council
video:
Weather radar images show a plume of snow downwind of the Rouyn-Noranda copper smelter in Canada. The weather radar is located near Landrienne, Canada.
Anthropogenic aerosols, tiny solid and liquid air pollution particles, have masked a fraction of global warming caused by anthropogenic greenhouse gases. Climate researchers have known for decades that anthropogenic aerosols perturb liquid clouds by enabling the formation of a larger number of cloud droplets, making clouds brighter. A new landmark study led by the University of Tartu suggests that anthropogenic aerosols may also influence clouds by converting cloud droplets to ice at temperatures below zero degrees Celsius.
Powerplant Snow
Using satellite observations, climate researchers discovered unique plumes of ice clouds and reduced cloud cover downwind of industrial hot spots in North America, Europe and Asia. Moreover, ground-based precipitation radar data revealed plumes of snowfall in the same areas where reduced cloud cover was observed in satellite images. Combining satellite and ground-based radar observations, researchers traced the physical processes from the formation of ice to snowfall to reduced cloud cover downwind of industrial hot spots. The lead author of the study, Assoc Prof V. Toll from the University of Tartu, highlighted that collaboration among researchers with diverse expertise was essential for developing the physical understanding of the identified anthropogenic snowfall events.
Supercooled Water
Water freezes at zero degrees Celsius, right? In fact, cloud droplets can stay liquid down to temperatures as low as about -40 degrees Celsius, known as the supercooling of water. This is because suitable aerosol particles are needed to convert cloud droplets to ice at temperatures between zero and -40 degrees Celsius. The study suggests that industries such as metallurgical and cement factories, coal-fired power plants, and oil refineries emit aerosol particles that cause freezing of supercooled liquid clouds, leading to snowfall. However, it is important to note that heat and water vapour emitted by industries may also play a role in the freezing of supercooled liquid clouds.
The discovered plumes of reduced cloud cover are local phenomena, and it remains unclear if anthropogenic aerosols induce ice formation in clouds at larger spatial scales. Further research is needed to understand the ability of various types of anthropogenic aerosols to initiate the formation of ice.
Glaciation of Liquid Clouds, Snowfall, and Reduced Cloud Cover at Industrial Aerosol Hot Spots
Article Publication Date
15-Nov-2024
The weather radar image shows a plume of snow downwind of the Rouyn-Noranda copper smelter in Canada. The weather radar is located near Landrienne, Canada.
The satellite image shows a plume of reduced cloud cover downwind of the Rouyn-Noranda copper smelter in Canada.
Observations of reduced cloud cover and snowfall downwind of industrial air pollution hotspot
The satellite image shows a plume of snow on the ground downwind of the Fokino cement plant in Russia.
Industrial air pollution triggers ice formation in clouds, reducing cloud cover and boosting snowfall
Summary author: Walter Beckwith
American Association for the Advancement of Science (AAAS)
Pollution from industrial hotspots can trigger ice formation in supercooled clouds, altering their reflective properties and increasing regional snowfall, according to a new study. The findings shed light on poorly understood impacts of anthropogenic aerosols on climate and could help improve climate modeling and mitigation strategies. The impact of human-generated aerosols (tiny air pollution particles) on climate, particularly in counteracting greenhouse gas-induced warming, remains uncertain. These aerosols, in addition to influencing cloud formation as cloud condensation nuclei (CCN), may also act as ice-nucleating particles (INPs), crucial for ice formation in supercooled liquid-water clouds at temperatures above -36 °degrees Celsius (°C). Anthropogenic INPs have been proposed to explain the plume-shaped snowfall patterns observed downwind of industrial sites, where emissions of heat, water vapor, and particles can influence cloud formation. However, a lack of observational evidence has prevented accurate assessment of the role of anthropogenic INPs in ice formation – or glaciation – of supercooled clouds and its potential impact on cloud cover and radiative fluxes. Using remote sensing data, including near-infrared satellite images from the satellite-based Moderate Resolution Imaging Spectroradiometer (MODIS) instrument, Velle Toll and colleagues observed the glaciation of supercooled clouds downwind of 67 aerosol-emitting industrial sites, such as metal and cement factories, paper mills, and powerplants. Toll et al. found that cloud glaciation from industrial aerosols, logged at various facilities in Canada and Russia, reduces solar radiation reflection by 13.7%, cloud cover by 8.3%, and cloud optical thickness by 18% while enhancing infrared radiance by 4.2% compared to unaffected clouds nearby. Additionally, the authors found that glaciation-induced snowfall greatly impacted local precipitation, with daily accumulations reaching up to 15 millimeters (mm), despite an average snowfall rate of 1.2 mm per hour, highlighting a measurable effect of industrial aerosols on localized snowfall patterns. The findings suggest that glaciation from anthropogenic ice-nucleating particles (INPs) could mirror the effects of pollution tracks in liquid clouds, highlighting the need for further investigation into the precise impact of anthropogenic INPs on cloud properties and climate. Additionally, rare glaciation events near nuclear power plants suggest factors other than INPs may also influence glaciation, such as local lofting of nearby aerosols by warm plumes.
Glaciation of liquid clouds, snowfall, and reduced cloud cover at industrial aerosol hot spots
Article Publication Date
15-Nov-2024
New study in Science finds that just four global policies could eliminate more than 90% of plastic waste and 30% of linked carbon emissions by 2050
Released on eve of UN plastic treaty negotiations in Busan, South Korea, comprehensive study reveals that an ambitious treaty can nearly eliminate plastic pollution — a threat to people, wildlife and the climate
University of California - Santa Barbara
Berkeley, CA/Santa Barabara, CA (14 November 2024) — A new study released in Science today determines that just four policies can reduce mismanaged plastic waste — plastic that isn’t recycled or properly disposed of and ends up as pollution — by 91% and plastic-related greenhouse gasses by one-third. The policies are: mandate new products be made with 40% post-consumer recycled plastic; cap new plastic production at 2020 levels; invest significantly in plastic waste management — such as landfills and waste collection services; and implement a small fee on plastic packaging. This policy package also delivers climate benefits, reducing emissions equivalent to taking 300 million gasoline-powered vehicles off the road for one year.
The study, “Pathways to reduce global plastic waste mismanagement and greenhouse gas emissions by 2050,” by researchers at the University of California Berkeley and the University of California Santa Barbara, comes in advance of negotiations in Busan, Republic of Korea (November 25-December 1), where delegates from more than 190 countries are expected to iron out the final details of the world’s first legally binding treaty on plastic pollution.
“This is it. These upcoming negotiations in Busan are our one chance to come together as a planet and fix this problem,” said Dr. Douglas McCauley, Professor at UC Santa Barbara, Adjunct Professor at UC Berkeley. “One of the most exciting discoveries in this research is that it is actually possible to nearly end plastic pollution with this Treaty. I'm cautiously optimistic, but we can’t squander this once-in-a-lifetime opportunity.”
If no action is taken in Busan, annual plastic consumption will rise 37% between 2020 and 2050, and plastic pollution will nearly double across the same period.
“This study demonstrates how far we have come in not just quantifying the manifold problems surrounding plastics, but also in identifying and evaluating potential solutions,” said Dr. Roland Geyer, Professor of Industrial Ecology, Bren School of Environmental Science & Management at UC Santa Barbara. “I am very proud of what our team was able to achieve in time for the final round of negotiations for the Global Plastics Treaty.”
By continuing with business as usual, the world would generate enough litter between 2011 and 2050 to cover Manhattan in a heap of plastic ten times the height of the Empire State Building. In a business-as-usual future, greenhouse gas emissions related to plastic would jump 37% from 2020 levels to 3.35 gigatons of carbon dioxide equivalent in 2050 — this is the same as nearly 9,000 natural gas-fired power plants operating for one year or the energy use for more than 436 million homes for one year.
“There are multiple pathways available to negotiators, but it does require ambition,” said Sam Pottinger, Senior Research Data Scientist, Eric and Wendy Schmidt Center for Data Science and Environment at UC Berkeley. “The impact that we're really hoping to see on the treaty is that it is data-informed. As the treaty comes to its final conclusion before ratification, we want folks to be aware of how much progress they've actually made, at least according to the best science that we have available right now.”
Countries in the Global South will continue to bear the greatest burden of the plastic crisis. Financing mechanisms created in the treaty could drive much-needed investment into waste management and recycling infrastructure in these regions to reduce plastic pollution — thus helping to solve a major global environmental justice issue.
“I’m optimistic about a sustainable future,” said Dr. Nivedita Biyani, Researcher on Global Plastic Modeling, Benioff Ocean Science Laboratory at UC Santa Barbara. “This policy work shows that we can reach minimal mismanaged plastic waste if we can come together in action. This provides policymakers with a novel tool that isn’t prescriptive — they can combine various policies as they see fit. Going forward, I think a mechanism to gather data on plastic production and trade will be a key factor. We need supply chain transparency here."
The study is built on insights from an AI-generated tool developed by a team of plastic researchers, data scientists, and AI researchers at the Benioff Ocean Science Laboratory and Bren School of Environmental Science & Management at University of California Santa Barbara, and the Eric and Wendy Schmidt Center for Data Science & Environment at University of California Berkeley. The tool uses machine learning to combine information about population growth and economic trends to forecast the future of plastic production, pollution and trade.
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Available for Interviews:
Dr. Douglas McCauley, Professor, UC Santa Barbara, Adjunct Professor, UC Berkeley
Dr. Roland Geyer, Professor of Industrial Ecology, Bren School of Environmental Science & Management at UC Santa Barbara
Dr. Nivedita Biyani, Researcher on Global Plastic Modeling, Benioff Ocean Science Laboratory at UC Santa Barbara
Mr. A Sam Pottinger, Senior Research Data Scientist, Eric and Wendy Schmidt Center for Data Science and Environment at UC Berkeley
Mr. Neil Nathan, Marine Science and Policy Specialist, Benioff Ocean Science Laboratory at UC Santa Barbara
Pathways to reduce global plastic waste mismanagement and greenhouse gas emissions by 2050
Article Publication Date
14-Nov-2024
Global plastic waste set to double by 2050, but new study offers blueprint for significant reductions
Summary author: Walter Beckwith
American Association for the Advancement of Science (AAAS)
Without intervention, global plastic waste could double by 2050, a new machine learning study predicts. However, according to simulations by the study’s authors, a mix of policy interventions could cut plastic waste by more than 90% and it could cut plastics-related emissions by a third. With UN treaty negotiations underway, these findings provide a crucial blueprint for tackling the plastic crisis. Plastic production has increased relentlessly for decades, leading to surging plastic waste generation and environmental mismanagement. As plastic degrades, it fragments into micro- and nano-plastics, which harm ecosystems globally – from the Arctic to deep ocean habitats – and pose significant health risks, including heightened cancer risks, cardiovascular disease, and reproductive issues. The plastic lifecycle also intensifies climate change through emissions from oil and gas extraction, production, and waste processing. The disproportionate plastic waste burden on the Global South and the frequency of situating plastic facilities near marginalized communities have sparked pressing environmental justice concerns. Recently, there has been global momentum to address these issues, culminating in a 2022 United Nations resolution to negotiate a legally binding treaty to curb plastic pollution.
To help in this effort, Samuel Pottinger and colleagues developed a novel machine learning model to forecast trends in global plastic production, trade, and waste management to 2050. They also simulated the effects of eight plausible policy interventions to mitigate waste and emissions. Pottinger et al. found that, without interventions, annual mismanaged plastic waste is anticipated to almost double by 2050, reaching 121 million metric tons. Concurrently, annual greenhouse gas emissions from the global plastic system are projected to rise by 37% over the same period. However, the authors also show that a combined policy intervention approach involving a production cap, recycling mandate, packaging tax, and infrastructure investment could reduce mismanaged plastic waste by up to 91% and decrease 2050 plastics-related emissions by about a third. “Collectively, these observations provide timely insight into how to maximize the impact of the UN plastic pollution treaty both as it is being drafted and over the longer time horizon of its implementation,” write Pottinger et al. “It is clear from these results that, with sufficient political will, there is enough technical potential to dramatically reduce mismanaged plastic waste and meaningfully address some of the more insidious associated issues.”
Pathways to reduce global plastic waste mismanagement and greenhouse gas emissions by 2050
Article Publication Date
14-Nov-2024
FLUE GAS
Breakthrough in capturing 'hot' CO2 from industrial exhaust
A metal-organic framework, or MOF, is capable of capturing CO2 at extreme temperatures
University of California - Berkeley
image:
At center left is one of the crystalline building blocks of a thermally stable metal-organic framework (MOF), known as ZnH-MFU-4l, that is able to reversibly and selectively capture the greenhouse gas carbon dioxide from a mix of many industrially relevant gases. CO2 is highlighted at left, among nitrogen, oxygen, hydrogen, carbon monoxide and water molecules. The MOF can capture CO2 over many cycles at 300 C, which is a typical temperature of the exhaust streams from cement and steel plants. The zinc hydride groups in the MOF reversibly bind and release the carbon dioxide molecules (right). Light-blue, gray, blue, red, and white spheres represent Zn, C, N, O, and H atoms, respectively.
Credit: Rachel Rohde, Kurtis Carsch and Jeffrey Long, UC Berkeley
Industrial plants, such as those that make cement or steel, emit copious amounts of carbon dioxide, a potent greenhouse gas, but the exhaust is too hot for state-of-the-art carbon removal technology. Lots of energy and water are needed to cool the exhaust streams, a requirement that has limited adoption of CO2 capture in some of the most polluting industries.
Now, chemists at the University of California, Berkeley, have discovered that a porous material can act like a sponge to capture CO2 at temperatures close to those of many industrial exhaust streams. The material — a type of metal-organic framework, or MOF — will be described in a paper to be published in the Nov. 15 print edition of the journal Science.
The dominant method for capturing carbon from power or industrial plant emissions employs liquid amines to absorb CO2, but the reaction only works efficiently at temperatures between 40 and 60 C (100–140 F). Cement manufacturing and steelmaking plants produce exhaust that exceeds 200 C (400 F), and some industrial exhaust approaches 500 C (930 F). New materials that are now being piloted, including a subclass of MOFs with added amines, break down at temperatures above 150 C (300 F) or work far less efficiently.
"A costly infrastructure is necessary to take these hot gas streams and cool them to the appropriate temperatures for existing carbon capture technologies to work," said UC Berkeley postdoctoral fellow Kurtis Carsch, one of two co-first authors of the paper. "Our discovery is poised to change how scientists think about carbon capture. We've found that a MOF can capture carbon dioxide at unprecedentedly high temperatures — temperatures that are relevant for many CO2 emitting processes. This was something that was previously not considered as possible for a porous material."
"Our work moves away from the prevalent study of amine-based carbon capture systems and demonstrates a new mechanism for carbon capture in a MOF that enables high temperature operation," said UC Berkeley graduate student and co-first author Rachel Rohde.
Like all MOFs, the material features a porous, crystalline array of metal ions and organic linkers, with an internal area equivalent to about six football fields per tablespoon — a huge area for adsorbing gases.
"As a result of their unique structures, MOFs have a high density of sites where you can capture and release CO2 under the appropriate conditions," Carsch said.
Under simulated conditions, the researchers showed that this new type of MOF can capture hot CO2 at concentrations relevant to the exhaust streams of cement and steel manufacturing plants, which average 20% to 30% CO2, as well as less concentrated emissions from natural gas power plants, which contain about 4% CO2.
Removing CO2 from industrial and power plant emissions, after which it is either stored underground or used to make fuels or other value-added chemicals, is a key strategy for reducing greenhouse gases that are warming Earth and altering the climate globally. While renewable energy sources are already reducing the need for CO2-emitting, fossil fuel-burning power plants, industrial plants that make intense use of fossil fuels are harder to make sustainable, so flue gas capture is essential.
"We need to start thinking about the CO2 emissions from industries, like making steel and making cement, that are hard to decarbonize, because it's likely that they're still going to be emitting CO2, even as our energy infrastructure shifts more toward renewables," Rohde said.
Moving from amines to metal hydrides
Rohde and Carsch conduct research in the lab of Jeffrey Long, UC Berkeley professor of chemistry, chemical and biomolecular engineering, and of materials science and engineering. Long has been conducting research on CO2-adsorbing MOFs for more than a decade. His lab created a promising material in 2015 that was further developed by Long's startup company, Mosaic Materials, which in 2022 was acquired by the energy technology company Baker Hughes. This material features amines that capture the CO2; next-generation variants are being tested as alternatives to aqueous amines for CO2 capture in pilot-scale plants, and as a way to capture CO2 directly from ambient air.
But those MOFs, like other porous adsorbents, are ineffective at the elevated temperatures associated with many flue gases, Carsch said.
Amine-based adsorbents, like those developed by Long, have been the focus of carbon capture research for decades. The MOF studied by Rohde, Carsch, Long and their colleagues instead features pores decorated with zinc hydride sites, which also bind CO2. These sites turned out to be surprisingly stable, Rohde said.
"Molecular metal hydrides can be reactive and have low stability," Rohde said. "This material is highly stable and does something called deep carbon capture, which means it can capture 90% or more of the CO2 that it comes into contact with, which is really what you need for point-source capture. And it has CO2 capacities comparable to the amine-appended MOFs, though at much higher temperatures."
Once the MOF is filled with CO2, the CO2 can be removed, or desorbed, by lowering the partial pressure of CO2, either by flushing with a different gas or putting it in a vacuum. The MOF is then ready to be reused for another adsorption cycle.
"Because entropy favors having molecules like CO2 in the gas phase more and more with increasing temperature, it was generally thought to be impossible to capture such molecules with a porous solid at temperatures above 200 C," Long said. "This work shows that with the right functionality — here, zinc hydride sites — rapid, reversible, high-capacity capture of CO2 can indeed be accomplished at high temperatures such as 300 C."
Rohde, Long and their colleagues are exploring variants of this metal hydride MOF to see what other gases they can adsorb, and also modifications that will allow such materials to adsorb even more CO2.
"We’re fortunate to have made this discovery, which has opened up new directions in separation science focused on the design of functional adsorbents that can operate at high temperatures,” said Carsch, who has taken a faculty position in the Department of Chemistry at The University of Texas at Austin. "There’s a tremendous number of ways we can tune the metal ion and linker in MOFs, such that it may be possible to rationally design such adsorbents for other high-temperature gas separation processes relevant to industry and sustainability.”
Other authors of the paper are Jeffrey Reimer, a UC Berkeley professor of chemical and biomolecular engineering, whose lab provided evidence from NMR spectroscopy to support the unique mechanism of CO2 capture by the zinc hydride sites in the MOF; Craig Brown of the National Institute of Standards and Technology in Gaithersburg, Maryland, who also provided critical structural data supporting the proposed mechanism; and UC Berkeley chemistry professor Martin Head-Gordon, whose lab provided a computational understanding of the high-temperature CO2 capture behavior. Other UC Berkeley authors include Andrew Minor, a UC Berkeley professor of materials science and engineering, and Matthew Dods, Henry Jiang, Alexandra McIsaac, Hyunchul Kwon, Sarah Karstens, Yang Wang, Adrian Huang, Jordan Taylor, Yuto Yabuuchi, Nikolay Tkachenko, Katie Meihaus, Hiroyasu Furukawa and Kaitlyn Engler.
Rohde was supported by a graduate fellowship from the National Aeronautics and Space Administration, while Carsch was supported by a postdoctoral fellowship from the Arnold O. Beckman Foundation.
