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)
Thursday, December 22, 2022
Overshooting climate targets could significantly increase risk for tipping cascades
POTSDAM INSTITUTE FOR CLIMATE IMPACT RESEARCH (PIK)
“We show that the risk for some tipping events could increase very substantially under certain global warming overshoot scenarios,” explains Nico Wunderling, scientist at the Potsdam Institute for Climate Impact Research and lead-author of the study to be published in Nature Climate Change. “Even if we would manage to limit global warming to 1.5 degrees after an overshoot of more than two degrees, this would not be enough as the risk of triggering one or more global tipping points would still be more than 50 percent. With more warming in the long-term, the risks increase dramatically.”
“To effectively prevent all tipping risks, the global mean temperature increase would need to be limited to no more than one degree – we are currently already at about 1.2 degrees,“ Jonathan Donges, Co-Lead of the FutureLab on Earth Resilience in the Anthropocene at PIK adds. “The latest IPCC report is showing that we’re most likely on a path to temporarily overshoot the 1.5 degrees Celsius temperature threshold.”
Emergence of at least one tipping event increases with rising peak temperatures
To arrive at these results, the scientists, together with co-authors from the Earth Commission – a group of leading scientists convened by Future Earth – used different global warming overshoot scenarios with peak temperatures from two to four degrees and applied these to a set of four interacting tipping elements: the Greenland Ice Sheet, the West Antarctic Ice Sheet, the Atlantic Meridional Overturning Circulation AMOC, and the Amazon rainforest. The researchers applied a risk analysis approach based on millions of model simulations to reflect the uncertainties in relevant parameters such as the uncertainty in critical temperature thresholds as well as interaction strengths and interaction structure. Such an amount of simulations would be computationally too expensive to do based on fully coupled Earth System Model simulations. For the different overshoot scenarios, the research team then analyzed the risk of crossing critical thresholds and the potential for triggering cascading interactions between the four elements, depending on the magnitude and duration of the overshoot as well as the warming remaining on the long-term.
“We found that the risk for the emergence of at least one tipping event increases with rising peak temperatures – already at a peak temperature of three degrees Celsius, more than one third of all simulations showed a tipping event even when overshoot durations were limited strongly. At four degrees Celsius peak temperature, this risk extends to more than half of all simulations,” explains Nico Wunderling.
Tipping mechanisms under warming overshoots
“Especially the Greenland and the West Antarctic ice sheet are at risk of tipping even for small overshoots, underlining that they are among the most vulnerable tipping elements. While it would take a long time for the ice loss to fully unfold, the temperature levels at which such changes are triggered could already be reached soon,” says Ricarda Winkelmann, Earth Commissioner and Co-Lead of the FutureLab on Earth Resilience in the Anthropocene. “Our action in the coming years can thus decide the future trajectory of the ice sheets for centuries or even millennia to come.” The other two tipping elements considered in the study, the AMOC and Amazon rainforest, have higher critical temperature thresholds. Yet, they would react much faster once the tipping process has started. Therefore, it is much more difficult to stop their tipping process once initiated by a temporary global warming overshoot.
Current mitigation policies are expected to lead to 2-3.6 degrees Celsius of global warming by the end of this century. “This is not enough. Even though a temporary temperature overshoot would definitely be better than reaching a peak temperature and remaining there, some of the overshoot impacts may lead to irreversible damages in a high climate risk zone and this is why low-temperature overshoots are key here,” explains Jonathan Donges. Ricarda Winkelmann adds: “Every tenth of a degree counts. We must do what we can to limit global warming as quickly as possible.”
Article: Nico Wunderling, Ricarda Winkelmann, Johan Rockström, Sina Loriani, David I. Armstrong McKay, Paul D. L. Ritchie, Boris Sakschewski, Jonathan F. Donges: Global warming overshoots increase risks of climate tipping cascades in a network model. Nature Climate Change. [DOI: 10.1038/s41558-022-01545-9]
Global warming overshoots increase risks of climate tipping cascades in a network model.
ARTICLE PUBLICATION DATE
22-Dec-2022
GUN NUT NATION
In some US zip codes, young men face more risk of firearm death than those deployed in recent wars
A study led by Brown University researchers puts the risk of firearm-related death in perspective and calls attention to the urgent need for violence reduction interventions in the U.S.
PROVIDENCE, R.I. [Brown University] — The risk of firearm death in the U.S. is on the rise: in 2020, firearms became the leading cause of death for children, adolescents and young adults. Yet the risk is far from even — young men in some U.S. zip codes face disproportionately higher risks of firearm-related injuries and deaths.
To better understand the magnitude of the gun violence crisis and put it in perspective, researchers at Brown University and the University of Pennsylvania compared the risk of firearm-related death for young adult men living in the most violent areas in four major U.S. cities with the risks of combat death and injury faced by U.S. military personnel who served in Afghanistan and Iraq during active periods of war.
The results were mixed: The study, published in JAMA Network Open, found that young men from zip codes with the most firearm violence in Chicago and Philadelphia faced a notably higher risk of firearm-related death than U.S. military personnel deployed to wartime service in Afghanistan and Iraq. But the opposite was true in two other cities: The most violent areas in New York and Los Angeles were associated with much less risk for young men than those in the two wars.
In all zip codes studied, risks were overwhelmingly borne by young men from minority racial and ethnic groups, the study found.
“These results are an urgent wake-up call for understanding, appreciating and responding to the risks and attendant traumas faced by this demographic of young men,” said Brandon del Pozo, an assistant professor of medicine (research) at Brown’s Warren Alpert Medical School and an assistant professor of health services, policy and practice (research) at the University’s School of Public Health.
Del Pozo conducts research at the intersection of public health, public safety and justice, focusing on substance use, the overdose crisis, and violence. His recently released book, “The Police and the State: Security, Social Cooperation, and the Public Good,” is based on his academic research as well as his 23 years of experience as a police officer in New York City and as chief of police of Burlington, Vermont.
“Working as a police officer, I witnessed the toll of gun violence, and how disruptive it was for families and communities,” del Pozo said. “It stood out to me that the burden was not distributed evenly by geography or demographic. Some communities felt the brunt of gun violence much more acutely than others. By analyzing publicly available data on firearm fatalities in cities and in war, we sought to place that burden in sharp relief.”
At the same time, del Pozo said, he and the other study authors were responding to oft-repeated inflammatory claims about gun violence in American cities.
“We often hear opposing claims about gun violence that fall along partisan lines: One is that big cities are war zones that require a severe crackdown on crime, and the other is that our fears about homicides are greatly exaggerated and don’t require drastic action,” del Pozo said. “We wanted to use data to explore these claims — and it turns out both are wrong. While most city residents are relatively safe from gun violence, the risks are more severe than war for some demographics.”
Illustrating the magnitude of the firearm crisis
To conduct their analysis, the researchers obtained information on all fatal and nonfatal shootings of 18- to 29-year-old men recorded as crimes in 2020 and 2021 in Chicago; Los Angeles; New York; and Philadelphia — the four largest U.S. cities for which public data on those who were shot were available. For New York, Chicago and Philadelphia, they used shooting death and injury data sets made public by each city; for Los Angeles, they extracted firearm death and injury data from a larger public data set of recorded crimes. Data were aggregated to the zip code level and linked to corresponding demographic characteristics from the U.S. Census Bureau’s 2019 American Community Survey.
The researchers acquired wartime combat-related mortality and injury counts for the conflicts in Iraq and Afghanistan from peer-reviewed analyses of U.S. military data covering the years 2001 to 2014 for the war in Afghanistan and 2003 to 2009 for the war in Iraq, both of which were periods of active combat. Because there is limited data about the risks of serving in different military units at different times during the Afghanistan and Iraq wars, the researchers considered the mortality and injury data of a single, de-identified Army brigade combat team engaged in combat during a 15-month period of the Iraq War that involved notably above-average combat death and injury rates at a time considered to be the height of the conflict.
The analysis included 129,826 young men residing in the four cities considered in the study.
The researchers found that compared to the risk of combat death faced by U.S. soldiers who were deployed to Afghanistan, the more dangerous of the two wars, young men living in the most violent zip code of Chicago (2,585 individuals) had a 3.23 times higher average risk of firearm-related homicide, and those in Philadelphia (2,448 people) faced a 1.9 times higher average risk of firearm-related homicide. Singling out the elevated dangers faced by the U.S. Army combat brigade in Iraq, the young men studied in Chicago still faced notably greater risks, and the ones faced in Philadelphia were comparable.
However, these findings were not observed in the most violent zip codes of Los Angeles and New York, where young men faced a 70% to 91% lower risk than soldiers in the Afghanistan war across fatal and nonfatal categories.
When the researchers looked at the demographics of the young men in the zip codes studied, they determined that the risk of violent death and injury observed in the zip codes studied was almost entirely borne by individuals from minority racial and ethnic groups: Black and Hispanic males represented 96.2% of those who were fatally shot and 97.3% of those who experienced nonfatal injury across all four cities.
In the study, the researchers make the point that the risk of firearm death is not the only thing that young men living in violent U.S. zip codes have in common with young men at war.
“Exposure to combat has been associated with stress-inducing hypervigilance and elevated rates of homelessness, alcohol use, mental illness and substance use, which, in turn, are associated with a steep discounting of future rewards,” they write. “Our findings — which show that young men in some of the communities we studied were subject to annual firearm homicide and violent injury rates in excess of 3.0% and as high as 5.8% — lend support to the hypothesis that beyond the deaths and injuries of firearm violence, ongoing exposure to these violent events and their risks are a significant contributor to other health problems and risk behaviors in many U.S. communities.”
Del Pozo added that the health risks are likely even higher for people in cities, because they need to face their “battles” every day over a lifetime, as opposed to military personnel in a tour of duty in Afghanistan, which typically lasted 12 months. The study results, del Pozo said, help illustrate the magnitude of the firearms crisis, a necessary understanding to municipalities seeking to formulate an effective public health response.
“The findings suggest that urban health strategies should prioritize violence reduction and take a trauma-informed approach to addressing the health needs of these communities,” del Pozo said.
Other Brown contributors included Dr. Michael J. Mello, a physician and researcher at the Warren Alpert Medical School and the Injury Prevention Center at Rhode Island Hospital.
The study was supported by the National Institute on Drug Abuse (K01DA056654) and the National Institute of General Medical Sciences (P20GM139664).
Comparing Risks of Firearm-Related Death and Injury Among Young Adult Males in Selected US Cities With Wartime Service in Iraq and Afghanistan
ARTICLE PUBLICATION DATE
22-Dec-2022
COI STATEMENT
Conflict of Interest Disclosures: None reported.
Rwandan tree carbon stock mapped from above
Breakthrough in climate change mitigation: Researchers at University of Copenhagen have developed accurate nation-wide mapping of the carbon content of trees based on aerial images
As the first country, Rwanda can now present a national inventory based on a mapping of the carbon stock of each individual tree. Researchers at University of Copenhagen have developed a method to achieve this task in collaboration with Rwandan authorities and researchers.
“Large uncertainties exist for the current forest assessments internationally. By mapping the carbon stock of all individual trees, accuracy is greatly improved. Further, the way different countries make their inventories is not consistent due to different contexts, goals, and available datasets. We hope that this method will establish itself as a standard, thereby enabling better comparisons between countries," says PhD Researcher Maurice Mugabowindekwe, Department of Geosciences and Natural Resources Management (IGN), University of Copenhagen. He is first author on the scientific article presenting the new method. The article has been accepted for publication by Nature Climate Change, one of the most prominent journals for the field.
Maurice Mugabowindekwe being Rwandan himself is helpful during the work, but the choice of Rwanda for development of the method was scientifically based, he emphasizes:
“The country has a rich landscape variation including savannas, woodlands, sub-humid and humid forests, shrubland, agro-ecosystem mosaics, and urban tree ecosystems which are representative of most tropical countries. We wanted to prove the method for all these landscape types. Moreover, Rwanda is a signatory to several international agreements on forest preservation and climate change mitigation. For instance, Rwanda has pledged to restore about 80 % of its surface area by 2030 under the Bonn Challenge. So, it is highly relevant to have a reliable method for monitoring tree carbon.”
First method for mapping individual trees
Preservation of natural forests and planting of new trees are recognized as vital routes to limiting climate change. However, large uncertainties regarding the carbon content of the trees have made it hard to assess the efficiency of concrete initiatives. The University of Copenhagen researchers have overcome this problem.
The new method benefits from databases which give the relationship between the extent of the crown and the total carbon content of an individual tree.
“Mapping individual trees and calculating their carbon stocks has traditionally been done in forestry, albeit at a much smaller scale. Basically, what we do equals scaling up these approaches from a very local to a national level," says Researcher Ankit Kariryaa, working 50:50 at IGN and at the Department of Computer Sciences (DIKU). Scientists from these two University of Copenhagen departments have developed the method with IGN as lead, in collaboration with other international scientists.
The new method will support Rwanda in verifying fulfilment of commitments under schemes such as the global forestry climate change mitigation scheme REDD+ or the African Forest Landscape Restoration Initiative, AFR 100.
Many trees are found outside forests
Manually mapping the trees of an entire country would be a huge endeavor and excessively costly. Thus, the new method constitutes a breakthrough since no other method would realistically be able to provide the same information at the level of individual trees.
“It is important to take a holistic approach and also include trees which are outside forests,” says Ankit Kariryaa, noting that 72 % of the mapped trees were in farmlands and savannas, and 17 % in plantations.
At the same time, the relatively small proportion of trees which are found in natural forests – 11 % of the total tree count – comprise about 51 % of the national carbon stock of Rwanda. This is possible mainly because natural forests have a very high carbon content per tree volume, thanks to the very low human disturbance secured through national legislation.
“This suggests that conservation, regeneration, and sustainable management of natural forests is more effective at mitigating climate change than plantation,” Maurice Mugabowindekwe comments.
Rainforest appears to be “a huge green blanket”
It is paramount that the computer can distinguish the individual trees. This is because the relationship between the extent of the crown and the total carbon content of a tree is very different depending on the size of a tree. One very large tree will have a much higher carbon content than a group of trees with the same joint crown extent. So, if the group was mistaken for one tree, the carbon content would be significantly overestimated. A deep neural network is used for detecting the individual trees.
“Especially for the rainforest, it is highly challenging to determine how many different trees are present in an image. At first glance, the forest just appears to be one huge green blanket. But by using methods from Machine Learning and Computer Vision, our system can also be applied to identify the individual trees in overstory of dense forests,” explains Christian Igel, Professor of Machine Learning at DIKU.
Training the computer on verified samples is at the core of Machine Learning. In the Rwandan study, the computer was trained on a set of some 97,500 manually delineated tree crowns representing the full range of biogeographical conditions across the country.
The study used publicly available aerial and satellite images of Rwanda at 0.25 x 0.25 m resolution. These images were collected in June-August 2008 and 2009 and were provided by the Rwanda Land Management and Use Authority and the University of Rwanda. More than 350 million trees were mapped.
Applications beyond Rwanda
Nine researchers from University of Copenhagen visited Rwanda in July 2022 with a dual purpose of field work and presenting results from the first nation-wide mapping to the Rwandan authorities and other stakeholders in the country’s forestry sector.
“The presentation was well received,” reports Maurice Mugabowindekwe. He was immediately tasked by the Rwandan authorities with an updated mapping based on newer aerial images acquired in 2019. This work is now ongoing.
Further, the method has already been tested for a handful of countries besides Rwanda. These include Tanzania, Burundi, Uganda, and Kenya.
“We hope countrywide high-resolution satellite imagery can also be acquired for these and more countries, to enable the application of the same approach. Also, we advocate the inclusion of funding for regular high-resolution imagery along with localized field inventory databases in development packages to enable similar works across the globe," says Maurice Mugabowindekwe, adding:
“The method has yielded good results when applied directly to a new country or region. If the model is further trained on a local set of samples, the accuracy becomes even higher. In my opinion, inventory of the available woody plants, their location, size, and carbon stock, is the first step towards monitoring the impact of landscape restoration efforts as well as conservation. If you are not able to create an accurate and reliable inventory, there is a risk of lacking a framework to track the impact of landscape restoration. This could make the conservation and sustainable management of both forests and other tree-dominated landscapes impossible. Therefore, this is science which is likely to have an impact.”
The scientific article “Nation-wide mapping of tree level carbon stocks in Rwanda” will be published in the prestigious journal Nature Climate Change [date], 2023.
Contacts:
Maurice Mugabowindekwe
PhD Researcher
Department of Geosciences and Natural Resources Management (IGN)
University of Copenhagen
mmu@ign.ku.dk
Phone +45 91 85 73 51
Ankit Kariryaa
Researcher
Department of Geosciences and Natural Resources Management (IGN)
A new study found bird diversity increased in North Carolina mountain forest areas severely burned by wildfire in 2016, reinforcing that while wildfire can pose risks to safety and property, it can be beneficial to wildlife. The study results could help forest managers better predict bird responses to wildfire, and manage forests to benefit birds.
“It’s important for us to understand the relationships between animals and wildfire dynamics as the climate changes because predictions show more of these high-severity wildfires across the landscape in the future,” said study co-author Chris Moorman, professor of forestry and environmental resources at North Carolina State University.
Wildfires burned more than 235 square miles of forest in the southern Appalachians in the fall of 2016, following a period of dry conditions and acts of arson. In the study published in the journal Forest Ecology and Management, researchers tracked different levels of burn severity in three forest regions of the Nantahala National Forest in western North Carolina.
Researchers counted the abundance and diversity of birds during the breeding season in those forest regions across five years. They used that data to compare bird communities in patches burned to different degrees of severity.
“Birds and other animals are well known to respond to forest vegetation structure, which is the distribution of plants vertically in a forest,” Moorman said. “When wildfire changes the vegetation structure, it has an impact on the animals that live there.”
In severely burned areas, researchers documented loss of most of the canopy trees, followed by the regrowth of dense shrubs and the re-sprouting of trees. In areas impacted by high severity fire, 44% of the trees died in the first year, and 71% had died by the fifth year. That compared to 7% tree mortality in unburned areas.
“After the high-severity wildfires, everything was brown and black and appeared dead,” Moorman said. “But changes happen fast in the southeastern U.S., and vegetation grew back rapidly.”
When they compared the numbers of birds in areas of different fire severity, they found an increase over time in the number of birds, as well as greater bird diversity, in forest areas where wildfire severity was high. By the fifth year, the total abundance of birds and the species richness, or number of different species present, in areas of high-severity burns were twice as high as that in unburned areas.
While it seems counterintuitive that high-severity patches supported more bird species, researchers said that’s because few species avoided the high-severity patches, but several species were more abundant or occurred only in those patches. More specifically, the indigo bunting, chestnut-sided warbler and eastern towhee – all species that breed in shrubs in areas with few or no canopy trees – occurred almost exclusively in the high-severity burn patches.
“When we do low-intensity prescribed fire under an intact tree canopy, we don’t benefit these bird species that prefer to nest in shrubland,” Moorman said. “In fact, low-severity burns – whether by wildfire or prescribed fire – have little effect on breeding bird species or communities at all.”
One species, the ovenbird, showed a trend of lower abundance in severely burned areas. However, the abundance of seven species was greatest in higher severity areas, and 11 species didn’t differ among the areas.
“I think a lot of the forest birds are not as particular as the literature might have previously suggested, as long as there is some vertical structure – like some live trees or standing snags – and cover,” said the study’s lead author Cathryn Greenberg, a research ecologist with the U.S. Forest Service. “Other studies show that even mature forest birds bring their young into recently disturbed areas, where insects and fruits are abundant, to learn how to forage under thick shrub cover for protection.”
Moorman said it’s likely that high-severity patches were small enough, or incomplete enough on the landscape, that it didn’t impact birds that live in the canopy or otherwise rely on the canopy trees.
“Most of the western NC landscape contains continuously closed canopy forest, so you get this new structural condition associated with canopy removal from high-severity burns that benefit shrubland bird species, but you still have the canopy present nearby for other birds,” Moorman said.
Researchers said the findings have implications for managing forests to promote bird diversity.
“It’s not a practical or logical approach to manage for high-severity wildfires across the landscape because of the obvious risks to safety and the loss of timber revenue,” Moorman said. “However, there are types of timber harvest that could create similar structural conditions to that created by high-severity wildfires.”
The study “Breeding bird abundance and diversity greatest in high-severity wildfire patches in central hardwood forests,” was published in Forest Ecology and Management. Co-authors included Katherine J. Elliott, Katherine Martin, Mark Hopey, and Peter Caldwell. The study was funded by the USDA Forest Service Coweeta Hydrologic Laboratory Southern Research Station; Nantahala Ranger District Southern Region 8; the Water Resources Program Washington Office; the National Science Foundation Long-term Ecological Research program (award #DEB-0823293); the USDA Institute of Food and Agriculture, Agricultural and Food Research Initiative Competitive Program, Agro-Ecosystem Management (award #2017-67019-26544); the Nature Conservancy; and the U.S. Forest Service North Carolina Supervisor’s Office.
-oleniacz-
Note to editors: The abstract follows.
“Breeding bird abundance and diversity greatest in high-severity wildfire patches in eastern hardwood forests”
Authors: Cathryn Greenberg, Christopher E. Moorman, Katherine J. Elliott, Katherine Martin, Mark Hopey and Peter V. Caldwell.
Published online on Dec. 15 in Forest Ecologyand Management.
Abstract: In 2016, mixed-severity wildfires in the southern Appalachians created a gradient of forest structures not typical following prescribed burns, providing a unique opportunity to study temporally dynamic conditions and breeding bird response. We measured forest structure and breeding bird communities across a fire-severity gradient in 3 burned and 3 unburned watersheds for 5 years (Y1-Y5). We categorized plots as unburned (NB), low- (L), moderate- (M), or high-severity (H) using a composite fire-severity index. Tree mortality increased with fire-severity category (FSC) and over time; by Y5, 7% of trees in NB, 11% in L, 38% in M, and 71% in H had died. Shrub recovery was rapid and most pronounced in H, exceeding other FSCs (70% vs 21%-44%) by Y5. Total bird abundance, species richness, and diversity increased over time in H (by Y3) and M (by Y4); by Y5, these metrics were highest in H and twice as high in H as in NB. Low-severity wildfires had no detectable effects on birds. Abundance of 7 species was greatest in higher-severity FSCs; 11 species did not differ among FSC, although ovenbirds (Seiurus aurocapilla) indicated a trend of lower abundance in H. No species was limited to NB, L, or M, whereas disturbance-dependent indigo bunting (Passerina cyanea), chestnut-sided warbler (Setophaga pensylvanica), and eastern towhee (Pipilo erythrophthalmus) were primarily associated with H. Increased richness and diversity were associated with heavy tree mortality and subsequent shrub recovery in H, accompanied by an influx of disturbance-dependent species and positive or neutral responses by most other species. Results highlight the interrelated roles of fire severity and time in driving forest structure and breeding bird response. Breeding birds responded to high-severity burns similarly to silvicultural treatments with heavy canopy reduction documented in other studies, offering possible alternatives when managing for breeding bird diversity in hardwood forests.
Blue Current achieves success with a breakthrough material originally discovered by the Joint Center for Energy Storage Research.
There is broad consensus that there is no silver bullet for climate change. Rather, many solutions will be required. What makes the challenge particularly daunting is the enormous reductions in greenhouse gas emissions needed in a short period of time. Some experts are concerned that there is not enough time to turn breakthrough scientific discoveries into the revolutionary products necessary to achieve aggressive decarbonization goals.
The Joint Center for Energy Storage Research (JCESR), an Energy Innovation Hub led by the U.S. Department of Energy’s (DOE) Argonne National Laboratory, recognized this dilemma when it launched in 2012. JCESR brings together more than 150 researchers from 20 institutions — including national laboratories, universities and industry — to build materials to enable breakthrough batteries.
“JCESR creates and proves the ideas that eventually go commercial,” said George Crabtree, JCESR’s director and an Argonne senior scientist. “These are the riskier ideas that no investors would fund — and that companies are unlikely to pursue — because the outcome is so uncertain. If proven, these ideas can drive the rapid progress on climate change that we need.”
“JCESR put resources behind composites because the materials had potential to address a market need for safe, solid-state batteries while solving important technical challenges. By proving these materials, JCESR made it a lot easier for us to move forward with the technology.” — Kevin Wujcik, Blue Current’s chief technology officer
The successful trajectory of JCESR spinoff company Blue Current points to the wisdom of this approach. In 2015, one of JCESR’s laboratories discovered a promising new battery material, known as a “composite,” that can make batteries dramatically safer. Inspired by the composite’s potential, Blue Current developed it further. Now, Blue Current is ramping up production of its battery cells. What’s more, an arm of Koch Industries has invested $30 million in the company to build its first megawatt-scale pilot factory in Hayward, California.
A focus on safety from the start
Safety is an important issue with batteries. When batteries are charged and discharged, substances known as electrolytes carry charge between the positive and negative electrodes. The liquid electrolytes found in many commercial lithium-ion batteries are flammable.
Since its founding, Blue Current’s top priority has been to develop a completely safe battery. At the same time, it has gone to great lengths to avoid the safety related design compromises that other battery companies have made. Its primary target market is electric vehicles (EVs).
“Helping the transition to sustainable energy is part of our core mission, and EVs provide the biggest platform to do that,” said Kevin Wujcik, Blue Current’s chief technology officer. Wujcik was on the JCESR research team that discovered the composite material. At the time, he was pursuing his Ph.D. studies at University of California, Berkeley.
Developing batteries for EVs is particularly challenging because many needs have to be met at once. “An EV battery has to be both a marathon runner and a sprinter,” said Wujcik. “It has to have a very long driving range and operate for a long time. But it also has to be able to charge very quickly. And it needs to work well in low and high temperatures.”
Two internationally recognized battery researchers founded Blue Current in 2014. Nitash Balsara is a JCESR scientist, a professor of chemical engineering at the University of California, Berkeley and a senior faculty scientist at Lawrence Berkeley National Laboratory. Joseph DeSimone, who was a chemistry professor at the University of North Carolina at Chapel Hill in 2014, is a Stanford chemical engineering professor today.
An early pivot
Solid-state batteries, which contain solid electrolytes, are much less flammable than liquid batteries. That’s why many battery developers view solid-state technologies as key to developing completely safe batteries. But solid electrolytes face many technical challenges, and no company has successfully commercialized a solid-state battery to date.
A crystalline class of solids known as glass ceramics have good conductivity, which is the ability to move lithium ions quickly. But they lack the ability to stick to the chemically active materials in battery electrodes that store lithium ions.
Another class of materials known as polymers — large molecules with repeating chemical units — are effective at sticking to electrodes. But they have low conductivity.
Initially, Blue Current focused on developing a battery cell with a nonflammable liquid electrolyte. Then, in 2015, as part of JCESR-sponsored research, Balsara’s lab made a breakthrough discovery that turned out to be a key formative event for Blue Current. The lab addressed the shortcomings of glass ceramics and polymers by bonding them together. The resulting composite solid electrolyte demonstrated good conductivity and good stickiness. Recognizing the composite’s potential to address key challenges with solid-state batteries, Blue Current pivoted to the solid-state field in 2016.
“By combining these materials, the JCESR discovery solved the challenges that each material faced on its own,” said Wujcik. “We decided that using composites was the best way to make the safest battery possible.”
“Getting the science right”
Initially, the anode (negative electrode) of Blue Current’s battery cell was made of lithium metal. Then, in 2018, the company decided to use silicon as the chemically active anode material. One reason for the switch was safety: Lithium metal is highly reactive and flammable, even in solid-state batteries.
Since 2018, the company has refined its composite electrolytes, silicon anode and other battery materials, with an aim of solving the technical challenges of solid-state technology.
“We have focused on getting the science right,” said Wujcik.
One solid-state challenge involves the amount of pressure needed for good battery performance. To help solid electrolytes stick to electrodes, some companies add heavy metal plates and bolts that put battery cells under high pressure. These fixtures increase manufacturing costs while reducing energy density — the amount of energy that can be stored in batteries per unit weight or volume. Lower energy density in EV batteries translates into shorter driving ranges unless the manufacturer increases the size and weight of the batteries. Shorter driving ranges tend to make EVs less attractive to consumers.
Blue Current’s vision has been to use the adhesiveness and elasticity of its composite electrolyte to lower the amount of pressure required for cells to operate. The composite is able to maintain good contact with silicon particles in the anode — without the use of heavy metal plates. This is an impressive achievement: Silicon expands and contracts as a battery cell charges and discharges, which makes it particularly difficult for solid electrolytes to maintain contact.
A second challenge that Blue Current has overcome involves temperature. Because polymer electrolytes have low conductivity, many solid-state battery developers use heating elements to raise the temperature of the cells. While the heat improves the polymers’ conductivity, it requires energy, reducing the battery’s cost-effectiveness. As a result, this approach is not viable for many commercial applications. Today, the high conductivity of Blue Current’s composite electrolytes enables its cells to operate effectively at room temperature.
Solid-state battery developers often struggle to design cost-effective, large-scale manufacturing processes. For example, solid-state cells with lithium metal anodes require specialized manufacturing equipment to avoid formation of dendrites during battery operation. Dendrites are needle-like lithium structures that make batteries less safe and less durable.
Blue Current has overcome this barrier by selecting affordable, abundant silicon anode materials. Additionally, it has designed its components so that they can be processed with the same equipment used by high-volume, lithium-ion battery manufacturers today.
Blue Current’s cells have demonstrated excellent performance. As part of rigorous safety testing, the company subjected its cells to harsh conditions that EVs could encounter in the real world, including crushing, puncturing and overcharging. Thermal runaway — an overheating event in batteries that can lead to fires — never occurred.
“If you get rid of thermal runaway, you make the battery a lot safer,” said JCESR’s Crabtree. “This is especially important in EVs. The batteries are located under the passenger seats.”
In other recent tests, Blue Current’s cells retained 85% of their energy capacity after more than 1,000 charge-discharge cycles — the equivalent of driving hundreds of thousands of miles. It’s a promising sign that the cells will last a long time. According to an EV industry rule-of-thumb, 80% capacity retention is excellent.
The path forward
Blue Current is currently outfitting its Hayward pilot manufacturing plant with high-volume manufacturing equipment. When completed in 2023, the plant will have an annual production capacity of 1–2 megawatt-hours. Here, it will develop the specifications for manufacturing even higher volumes. “The plant is going to lay the groundwork for the next facility,” said Wujcik.
Blue Current also plans to remain focused on research and development. “We’re seeing the battery industry shifting towards the use of silicon anodes to improve the performance of both traditional lithium-ion batteries and next-generation, solid-state batteries,” said Wujcik. “Because the solid-state silicon field is still in an early stage, it’s essential for us to continue our efforts developing new materials.”
Indeed, Blue Current’s success with solid-state silicon batteries opens up a new field for researchers and other companies to explore. “There’s a lot of work that can be done in this space,” said Wujcik. “Researchers can investigate which solid electrolytes and silicon materials to use and how composite electrolytes stick to anode materials.”
Wujcik expressed appreciation for JCSER’s important role in Blue Current’s success.
“The idea of using composites in batteries was new and unproven prior to the JCESR program,” he said. “JCESR put resources behind composites because the materials had potential to address a market need for safe, solid-state batteries while solving important technical challenges. By proving these materials, JCESR made it a lot easier for us to move forward with the technology.”
The Joint Center for Energy Storage Research (JCESR), a DOE Energy Innovation Hub, is a major partnership that integrates researchers from many disciplines to overcome critical scientific and technical barriers and create new breakthrough energy storage technology. Led by the U.S. Department of Energy’s Argonne National Laboratory, partners include national leaders in science and engineering from academia, the private sector, and national laboratories. Their combined expertise spans the full range of the technology-development pipeline from basic research to prototype development to product engineering to market delivery.
Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.
The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science.
IMAGE: PME RESEARCHERS COLLECTED DATA ON HOW DIFFERENT COMPONENTS OF A THICK LITHIUM ION BATTERY ELECTRODE EVOLVE AFTER SUCCESSIVE CYCLES (ONE SNAPSHOT OF THE MICROSCOPY DATA SHOWN ON THE LEFT). THEN, THEY USED THIS DATA TO CREATE A COMPUTATIONAL MODEL (RIGHT) ILLUSTRATING THE DEGRADATION AND POINTING TOWARD HOW TO IMPROVE THE LIFESPAN OF THE BATTERIES.view more
CREDIT: IMAGE COURTESY OF THE LABORATORY FOR ENERGY STORAGE AND CONVERSION.
From the moment you first use it, a new lithium-ion battery is degrading. After a few hundred charge cycles, you’ll notice — your phone, laptop or electric car battery wears out more quickly. Eventually, it stops holding a charge at all.
Researchers at the University of Chicago’s Pritzker School of Molecular Engineering (PME) have now used a combination of high-powered electron microscopy and computational modeling to understand, at an atomic level, exactly what occurs when lithium-ion batteries degrade. Their research points toward one approach to designing longer-lasting lithium-ion batteries — by focusing on an oft-ignored structural component, the carbon binder domain (CBD).
“To tackle many of the world’s energy storage and conversion challenges over coming decades, we need to keep innovating and improving batteries,” said Prof. Y. Shirley Meng, who led the research, published in the journal Joule. “This work is one step toward more efficient and sustainable battery technology.”
Limited Charge Cycles
The widespread commercialization of lithium-ion batteries at the end of the twentieth century played a role in the advent of lightweight, rechargeable electronics. Lithium is the lightest metal and has a high energy density-to-weight ratio. When a lithium-ion battery is charged, lithium ions move from a positively charged cathode to a negatively charged anode. To release energy, those ions flow back from the anode to the cathode.
Throughout charging cycles, the active materials of the cathode and anode expand and contract, accumulating “particle cracks” and other physical damage. Over time, this makes lithium-ion batteries work less well.
Researchers have previously characterized the particle cracking and degradation that occurs in small, thin electrodes for lithium-ion batteries. However, thicker, more energy-dense electrodes are now being developed for larger batteries — with applications such as electric cars, trucks and airplanes.
“The kinetics of a thick electrode are quite different from those of a thin electrode,” said project scientist Minghao Zhang of the University of California San Diego, a co-first author of the new paper. “Degradation is actually much worse in thicker, higher-energy electrodes, which has been a struggle for the field.”
It’s also harder to quantitatively study thick electrodes, Zhang pointed out. The tools that previously worked to study thin electrodes can’t capture the structures of larger, denser materials.
Combining Microscopy and Modeling
In the new work, Meng, Zhang and collaborators from Thermo Fisher Scientific turned to Plasma focused ion beam-scanning electron microscopy (PFIB-SEM) to visualize the changes that occur inside a thick lithium-ion battery cathode. PFIB-SEM uses focused rays charged ions and electrons to assemble an ultra-high-resolution picture of a material’s three-dimensional structure.
The researchers used the imaging approach to collect data on a brand new cathode as well as one that had been charged and depleted 15 times. With the data from the electron microscopy experiments, the team built computational models illustrating the process of degradation in the batteries.
“This combination of nanoscale resolution experimental data and modeling is what allowed us to determine how the cathode degrades,” said PME postdoctoral research fellow Mehdi Chouchane, a co-first author of the paper. “Without the modeling, it would have been very hard to prove what was happening.”
The researchers discovered that variation between areas of the battery encouraged many of the structural changes. Electrolyte corrosion occurred more frequently with a thin layer at the surface of the cathode. This top layer therefore developed a thicker resistive layer, which led the bottom layer to expand and contract more than other parts of the cathode, leading to faster degradation.
The model also pointed toward the importance of CBD — a porous grid of fluoropolymer and carbon atoms that holds the active materials of an electrode together contribute and helps conduct electricity through the battery. Previous research has not characterized how the CBD degrades during battery use, but the new work suggested that the weakening of contacts between the CBD and active materials of the cathode directly to the decline in performance of lithium-ion batteries over time.
“This change was even more obvious than the cracking of the active material, which is what many researchers have focused on in the past,” said Zhang.
Batteries of the Future
With their model of the cathode, Meng’s group studied how tweaks to the electrode design might impact its degradation. They showed that changing the CBD structure network could help prevent the worsening of contacts between the CBD and active materials, making batteries last longer — a hypothesis that engineers can now follow up with physical experiments.
The group is now using the same approach to study even thicker cathodes, as well as carrying out additional modeling on how to slow electrode degradation.
Said Dr. Zhao Liu, senior manager for battery market development at Thermo Fisher Scientific, who contributed to the research, “This study develops a methodology of how to design electrodes to enhance future battery performance.”
Scientists at the U.S. Department of Energy’s (DOE) Institute for Cooperative Upcycling of Plastics (iCOUP) have developed a new method for recycling high-density polyethylene (HDPE).
Using a novel catalytic approach, scientists at DOE’s Argonne National Laboratory and Cornell University converted post-consumer HDPE plastic into a fully recyclable and potentially biodegradable material with the same mechanical and thermal properties of the starting single-use plastic.
Why it matters:
HDPE is ubiquitous in single-use applications because it is strong, flexible, long-lasting and inexpensive. But the ways we produce and dispose of HDPE pose serious threats to our own health and that of our planet.
Many HDPE products are produced from fossil fuels, and most post-consumer HDPE is either incinerated, dumped in landfills or lost in the environment. When it is recycled with current methods, the quality of the material degrades.
This new approach could reduce carbon emission and pollution associated with HDPE by using waste plastic as untapped feedstock and transforming it into a new material that can be recycled repeatedly without loss of quality.
The details:
Current HDPE recycling approaches yield materials with inferior properties. The team’s alternative approach uses a series of catalysts to cleave the polymer chains into shorter pieces that contain reactive groups at the ends. The smaller pieces can then be put back together to form new products of equal value. The end groups have the added benefit of making the new plastic easier to decompose, both in the lab and in nature.
A paper on the results was published December 16 in the Journal of the American Chemical Society.
This work was supported as part of iCOUP, an Energy Frontier Research Center funded by the DOE Office of Science, Basic Energy Sciences at Argonne and Ames Laboratory. This work made use of the NMR Facility at Cornell University, supported by the National Science Foundation.
Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.
The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science.
