Safer metal recycling for the battery industry

Chalmers University of Technology

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Mark Foreman, Associate Professor, Division of Energy and Materials,Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Sweden

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Credit: Chalmers University of Technology

The metals used in batteries are a valuable, finite resource that are not readily available in Europe. There is therefore a huge desire to recycle as much as possible. Researchers at Chalmers University of Technology in Sweden have come up with a new way of recycling the metals found in rechargeable batteries, with less harmful effects for people and the environment, whilst maintaining the same level of efficiency. Their study investigates how fossil-based chemicals used in metal recovery can be replaced with alternatives produced from renewable biomass.

A rise in global energy consumption and the need to use more sustainable energy systems wherever possible is driving an increasing demand for energy storage systems, such as batteries. At the same time, the need to recover and recycle the metals used in batteries – including copper, cobalt, lithium and manganese – is also increasing. These materials are essential for the green transition, and several of them are included in the EU Critical raw materials act.

Critical raw materials are “raw materials of high economic importance for the EU, with a high risk of supply disruption due to the concentration of their sources and the lack of any good, affordable substitutes”. For example, China supplies 100 per cent of the EU’s demand for heavy rare earth elements. The EU is working to diversify and secure its supply of critical raw materials, and recycling is playing a key role.

Batteries require high degree of purity

To make metal recovery both efficient and economically viable, metals must be separated and purified before they can be reused. The production of batteries and other high-value products often requires metals of a high degree of purity.

In some cases, using higher-purity raw materials can lead to the exclusion of less favorable materials (for both the environment and human safety), such as mercury. For example, in the past, the shelf life of non-rechargeable batteries was extended by adding mercury to the zinc electrode. However, with higher-purity zinc, it is possible to produce an equally stable battery that is free from mercury.

“If we do not separate and purify materials during recycling, their quality will gradually deteriorate. Ultimately, we risk ending up with materials that can no longer be used in advanced applications, and the whole purpose of recycling is lost,” says Mark Foreman, Associate Professor at the Department of Chemistry and Chemical Engineering at Chalmers.

Alternatives for existing production lines

Solvent extraction is a widely used method (read more below) for separating and purifying metals in battery recycling, as well as in mining, the nuclear industry and in other industrial sectors. Today, the diluents used in these processes are typically produced from fossil-based feedstocks.

“In our study, we wanted to demonstrate that renewable biomass, for example, by-products from the forestry industry, can be used to produce alternative diluents. In this case, we investigated two aromatic compounds that could also be used directly in existing industrial production lines,” says Daniel Keywan Hoffmann, PhD student at Chalmers and first author of the study.

The study shows that the aromatic compounds perform just as well as conventional commercial alternatives in the extraction of several important metals. Furthermore, they could be implemented directly in existing industrial production lines.

“It is expensive for industry to rebuild factories or invest in entirely new infrastructure to improve sustainability. If the existing processes and equipment can be used while simply switching to a significantly safer chemical, the barrier to change becomes much lower and far less expensive,” says Daniel Keywan Hoffmann.

The aromatic compounds are safer to handle

Large-scale metal recovery operations use substantial quantities of diluents, which often need to be handled by people, so safety considerations are of particular importance. The researchers found that the two aromatic compounds used in the study have higher flash points and lower volatility than several commercially used alternatives. This means a lower risk of fire and reduced exposure to hazardous substances for workers in recycling facilities.

Some commercial chemicals used frequently for these processes today are particularly potentially harmful, since they form a group of neurotoxins when they degrade. These neurotoxins can have harmful effects in the brain and nervous system of humans and animals, and many conventional diluents are converted into these in the body.  The new aromatic compounds which have been tested in this study cannot form these neurotoxins when they degrade.

“If we can achieve the same performance as current processes while reducing risks to people and the environment, that represents a significant benefit for everyone,” says Mark Foreman.

Aim to inspire industry

The researchers emphasise that manufacturing processes would need to be optimised, and the availability of renewable feedstocks increased, to make the approach cost-effective.

“We hope our work can inspire industry to think differently. Sustainable alternatives do not necessarily require starting from scratch. In many cases, replacing certain chemicals may be enough,” says Daniel Keywan Hoffmann.

 

 

More about the study:

• Read the study in RSC Sustainability: Safer aromatic process diluents for solvent extraction of critical metals from spent batteries
• Liquid–liquid extraction, also known as solvent extraction, uses an organic phase consisting of:
  a) A complex-forming molecule (extractant) that binds the metal to be extracted.
  b) A diluent in which the extractant is dissolved, such as kerosene.
• The primary role of the diluent is to dissolve the extractant and create a usable organic phase, as extractants cannot generally be used on their own.

Researchers at Chalmers University of Technology in Sweden have come up with a new way of recycling the metals found in rechargeable batteries, with less harmful effects for people and the environment, whilst maintaining the same level of efficiency. This study investigates how fossil-based chemicals used in metal recovery can be replaced with alternatives produced from renewable biomass. This image shows how the new biobased dilutents are created. The feedstock molecules (which can come from forestry waste and waste from bioalcohol production) are shown in blue on the left. These pass through sulfuric acid and create the new biobased dilutents, seen on the right in grey and white, which can be used for safer battery recycling. 

Credit

Chalmers University of Technology | Mark Foreman

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Journal

RSC Sustainability

DOI

10.1039/D6SU00096G 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Safer aromatic process diluents for solvent extraction of critical metals from spent batteries

 

China's massive battery capacity buildout – Statista

Already accounting for half of the world's solar panels, China is completing its green revolution by building out massive battery storage capacity. / bne IntelliNews

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By Felix Richter of Statistia July 8, 2026

China’s lead in renewable energy is matched by its dominance in battery storage, Statista reports.

According to data from the Energy Institute’s latest Statistical Review of World Energy, the country’s grid-scale battery energy storage capacity surged from just 2.4 gigawatts in 2020 to more than 140 gigawatts in 2025 – far ahead of the United States, which reached roughly 57 gigawatts, and the rest of the world.

This rapid expansion is closely linked to the rise of wind and solar power in the country. Unlike conventional power plants, renewable sources generate electricity intermittently, depending on weather conditions and time of day. Battery storage systems help to smooth out these variations by storing excess electricity and feeding it back into the grid when needed, making large-scale renewable integration more feasible.

In that sense, China’s storage boom is a direct consequence of its clean energy push. As renewable capacity continues to grow, so does the need for flexibility in the power system. By investing heavily in battery storage, China is addressing one of the key challenges of the energy transition, ensuring that its massive buildout of wind and solar power can be used efficiently and reliably.

Policymakers have actively encouraged this development, with many regions requiring new renewable projects to include co-located storage capacity. These measures, combined with falling battery costs and strong domestic manufacturing capabilities, have turned China into the world’s largest market for battery energy storage systems.

 

You will find more infographics at Statista

 

Social norms can accelerate or undermine climate action, new model finds

University of Waterloo-led research shows cultural attitudes in one region can unexpectedly influence climate action around the world

University of Waterloo

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A new mathematical model suggests that social norms may be just as important as economics in determining how the world responds to climate change. The research shows that efforts to reduce emissions in one region can unintentionally influence climate action elsewhere, with consequences that could either strengthen or weaken global progress.

The model divides the world into five culturally and economically distinct regions and simulates how social norms, perceived climate risks and economic pressures interact to shape climate action.

"Climate models often assume people are rational economic actors who always act in their own best interest," said Dr. Chris Bauch, professor of applied mathematics at the University of Waterloo. "Our model recognizes that people are also influenced by social norms, whether that's eating more beef or choosing reusable water bottles, and those behaviours can significantly affect climate change mitigation."

The model draws on existing data describing cultural values and behaviour across Asia, Latin America, the Middle East and Africa, OECD countries and the Reforming Economies of Eastern Europe and the former Soviet Union. It models how social and economic factors influence mitigation efforts, which in turn affect global warming.

The researchers found that strategies that encourage climate action in one region may have the opposite effect elsewhere.

"We found that greater discussion about climate change often increases support for mitigation, but in some regions, it can also fuel anti-mitigation sentiment," said lead author Amrita Punnavajhala, who recently completed her PhD in applied mathematics at Waterloo. "The best approach depends on each region's unique social and economic circumstances rather than a one-size-fits-all solution."

The model also reveals how regional actions can create unexpected ripple effects.

"If Asia increases its mitigation efforts, global warming slows slightly, which can reduce the perceived urgency in OECD countries such as Canada and the United States," Bauch said. "That could weaken social pressure for climate action and create harmful long-term consequences."

"There are constant feedback loops between climate change and human behaviour," said Dr. Madhur Anand, professor of environmental science at the University of Guelph and adjunct professor in Waterloo's Department of Applied Mathematics. "Understanding those relationships will be essential to reducing emissions and building a more sustainable future."

The study, Implications of regional variations in climate change vulnerability and mitigation behaviour for social-climate dynamics, appears in Nature Communications.

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Journal

Nature Communications

 

Hotter, drier weather could double water bills in some cities, Stanford study finds

Stanford University

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WATCH RELATED VIDEO HERE: https://www.youtube.com/watch?v=U6I-qK-4si0

In Brief

• Hotter, drier conditions driven by climate change could nearly double water bills in some cities by mid-century, according to a Stanford-led study.
• Researchers found that costly drought-resilience projects, such as desalination and water reuse systems, could push many low-income households into severe water affordability crises.
• The study suggests current financing models are ill-equipped to balance reliable water supplies with affordable access as climate pressures intensify.

Hotter, drier weather threatens to double water bills by mid-century in some cities, according to a Stanford-led study. The research, published July 8 in Nature Sustainability, is the first to comprehensively model how climate change, infrastructure investment, and household water demand can combine to compound an already growing affordability crisis.

"Climate change stresses water supplies, and forces utilities to build expensive new infrastructure to maintain reliability,” said study lead author Jennifer Skerker, a PhD student in civil and environmental engineering at the Stanford Doerr School of Sustainability and the Stanford School of Engineering while working on the study. “In cities already struggling with affordability due to aging infrastructure, the additional costs passed on to ratepayers to pay for additional infrastructure and reliability measures can push a substantial share of households into crisis.”

The average cost of tap water in the United States has increased three times faster than inflation over the past two decades, driven largely by aging infrastructure and deferred maintenance. Climate change is layering a new and poorly understood pressure on top of those existing strains, according to Skerker and her study coauthors.

To understand how predicted changes in temperature and rainfall over the next two decades are likely to affect local water supplies and costs, the research team analyzed data from Santa Cruz, California. The small coastal city relies almost entirely on local surface water and a single reservoir. The local utility has implemented many lower-cost conservation options, such as water-saving appliances and reduced irrigation, necessitating infrastructure investments for climate resilience.

Using a modeling framework developed with data from Santa Cruz's water department, the researchers linked plausible future climate scenarios with utility adaptation decisions, such as building a wastewater reuse facility, methods for pricing water, and household-level water demand. Among the results: measures taken to adapt to less water availability could lead to a near doubling of median water bills in Santa Cruz by mid-century. Paying for major new infrastructure could push the share of households exceeding the EPA’s recommended affordability threshold from the 19% to 35%, according to the study’s findings.

The model showed median water bills for the poorest residents could rise from around $60 to $111 per month (in today’s dollars) under a dry climate scenario. More than 5% of households would have to devote as much as a third of their income to water, likely forcing painful trade-offs with food, healthcare, and other necessities.

Different infrastructure strategies produced starkly different outcomes. A risk-averse approach that built large desalination capacity early provided strong supply reliability, but at a steep cost to affordability. A more cautious approach that delayed investments kept bills lower but left the system dangerously exposed during droughts, providing reliable water supply in only 6 out of 10 years on average. 

The modeling framework can be adapted to assess water affordability risks in cities – such as Los Angeles, San Diego, San Francisco, Cape Town, and Melbourne, Australia – facing vulnerabilities similar to those of Santa Cruz. Even cities that seem more resilient now would do well to pay attention. They could become vulnerable over time as climate stress intensifies and utilities raise water rates, according to the researchers.

"The bottom line is that under today's financing and regulatory models, climate adaptation and water affordability are on a collision course,” said study senior author Sarah Fletcher, an assistant professor of civil and environmental engineering and a center fellow at the Stanford Woods Institute for the Environment. “Ensuring reliable water access for everyone is going to require interventions at the state and federal level that go far beyond what individual utilities can do on their own.”

 

Other coauthors of the study include Christian Klassert of the Helmholtz Centre for Environmental Research; Baptiste Francois and Casey Brown of the University of Massachusetts; and Aniket Verma, a Ph.D. student in civil and environmental engineering at Stanford.

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Journal

Nature Sustainability

DOI

10.1038/s41893-026-01890-z 

Article Title

Urban water affordability crisis exacerbated by climate change

Article Publication Date

8-Jul-2026

 

Global warming and increasing wildfire risk threaten viability of elite wine-growing regions in California – but others may boom

Mendocino and Monterey could become increasingly favorable for premium vintages under shifting climate, while Napa and Sonoma may face increased pressure in grape cultivation

Frontiers

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The US is the fourth-largest wine-producing country by output volume, and approximately 80% of its production occurs in California. Ever since the 19th century, California’s premier wine-growing regions have been the Napa Valley and Sonoma County, thanks to their favorable microclimate. But grape yield and quality are very sensitive to the local environment, which means  that the climate crisis could shake up California’s wine industry. A new study shows that established regions including Napa and Sonoma could struggle to sustain their wine production under severe climate change. Others, like northern and coastal California, could become new wine-growing powerhouses.

“Our findings reveal that the outlook for Mendocino and Monterey is uniquely promising because of a dual trend: they are projected to experience both increasing climatic suitability for wine-growing and a decrease in extreme fire-weather days,” said Dr Yusuke Hiraga, an assistant professor at Tohoku University in Sendai, Japan, and corresponding author of the study in Frontiers in Climate. “This combination makes these areas stand out as comparatively favorable expansion zones, distinct from many other regions with either rising suitability alongside increased wildfire weather or declining suitability.”

Wildfires and global warming

Together with Mr Takuya Matsumoto, a master student at Tohoku University, Hiraga modeled California’s current and future climatic suitability for wine grape cultivation. They focused on 379 wine-growing locations listed in the California Wine Institute, predominantly in the North Coast region and across the Central Coast.

To forecast climate change, the authors mapped projections from global climate models onto a 4km-by-4km grid across the mainland US. They considered two alternative carbon emission scenarios from the Intergovernmental Panel on Climate Change: RCP4.5, which assumes that mitigation policies are gradually implemented, and the ‘worst-case scenario’ RCP8.5. For each scenario, they modeled three periods: between 1976 and 2005 (‘baseline’), 2040-2069 (‘mid-century’), and 2070-2099 (‘late century’). Each grid cell’s suitability for growing grapes and the expected quality of its vintage was predicted with a machine learning algorithm. To capture wine quality, the scientists trained an algorithm on wine ratings by professional tasters, published between 1996 and 2023 in the magazine Wine Spectator.

The authors likewise modeled the shifting weather conditions linked to wildfire risk and expected severity within each cell. These were expressed as the Fire Weather Index (FWI), calculated from climatic variables like moisture and wind speed. A higher FWI implies a greater likelihood that accidental ignitions will turn into conflagrations.

In vino veritas

The results showed that the suitability of currently important wine-growing regions, like Napa, Sonoma, San Luis Obispo, and Santa Barbara, is likely to decline strongly under severe climate change. In contrast, suitability was predicted to increase greatly in Mendocino, Monterey, and in central to southern coastal areas. Suitability was found to depend mostly on yearly total precipitation, cumulative temperature across the growing season between early April and late October, the minimum temperature of the coldest month, and the vapor pressure deficit – the difference between how much moisture the air holds and how much it holds when saturated.

The number of days with extreme wildfire weather conditions tended to increase across large swathes of California, but especially in northern regions and inland high-elevation areas. However, this decreased in large parts of Mendocino and Monterey. The expected wine producing suitability tended to be greater under RCP4.5 than under RCP8.5 for late century, suggesting that higher greenhouse gas emissions could lead to a decline in the vintage.

“While our study highlights long-term shifts in climatic and fire-weather suitability through the end of the century, it does not attempt to predict a specific timeline for when emerging areas will surpass currently established regions in wine-growing potential,” warned Hiraga. “Such a precise forecast is complex, as the future of viticulture is shaped not only by climate change and wildfire weather but also by a wide array of anthropogenic factors.”

What is the authors’ advice to vintners in currently established, high-profile regions?

“The path forward requires active adaptation to both shifting climatic conditions and increasing wildfire risk. Our analysis suggests that proactive strategies – such as careful varietal selection – will be critical, as our models indicate that different grape varieties respond quite differently to extreme fire-weather conditions,” said Hiraga.

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Journal

Frontiers in Climate

DOI

10.3389/fclim.2026.1838268 

Method of Research

Computational simulation/modeling

Subject of Research

Not applicable

Article Title

Dual pressures of climate change and wildfire hazard on wine-growing potential in California

Article Publication Date

8-Jul-2026

 

A review of the climatology features and mid- and high-latitude forcing of the equatorial electrojet

Beijing Zhongke Journal Publising Co. Ltd.

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image: 

A conceptual diagram demonstrating how subauroral polarization streams (SAPS, right panel) in the subauroral region generate electric fields that map along Earth's magnetic field lines, establishing a vertical polarization electric field in the equatorial ionosphere to modulate the daytime equatorial electrojet (EEJ, left panel).

view more 

Credit: Beijing Zhongke Journal Publishing Co. Ltd.

The equatorial electrojet (EEJ) is an intense, narrow eastward current system flowing within the daytime ionospheric E region (~105–110 km altitude) along the magnetic dip equator. As a crucial component of low-latitude space weather, understanding the EEJ's variability is essential for protecting global communication and navigation networks.  Led by researchers from Wuhan University, this newly published review presents a systematic synthesis of the spatial and temporal evolution of the EEJ. Under geophysically quiet conditions, the EEJ displays pronounced local time and longitudinal variations. Ground and satellite observations demonstrate that while solar photoionization controls its daytime peak near local noon, nonmigrating atmospheric tides originating from tropical tropospheric convection dictate its global wave-4 longitudinal structure.  Beyond quiet-time climatology, the review pays critical attention to the EEJ’s behavior under highly volatile space weather conditions. It delineates how energy inputs from mid- and high-latitude regions can rapidly alter or even reverse the electrojet's direction—creating a westward counter electrojet (CEJ). These perturbations are driven by two main processes: prompt penetration electric fields (PPEF) that map instantly from high latitudes during storms, and disturbance dynamo electric fields (DDEF) driven by long-lasting storm-time thermospheric winds. Other cross-regional factors, such as magnetospheric substorms, sudden changes in solar wind dynamic pressure, subauroral polarization streams (SAPS), and sudden stratospheric warmings (SSWs), are shown to introduce stark asymmetries into low-latitude dynamics.  Furthermore, the review addresses the distinct pathways of solar radiative forcing, such as solar flares and eclipses, which modulate the EEJ through rapid adjustments in ionospheric conductivity and dynamo interactions.  While state-of-the-art physics-based numerical simulations (like the TIEGCM) and data-driven empirical frameworks have successfully reproduced basic seasonal and diurnal structures, their quantitative consistency remains limited during major space weather disturbances. The authors point out critical open issues, including the lack of unified frameworks for multi-factor coupling and the unmodeled nonlinear responses of the ionosphere. Resolving these bottlenecks will require the strategic integration of multi-platform coordinated observations, refined parameterizations of high-latitude boundaries, and data-driven machine learning models.

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Journal

Earth and Planetary Physics

DOI

10.26464/epp2026055 

Article Title

A review of the climatology features and mid- and high-latitude forcing of the equatorial electrojetcation

Beijing Zhongke Journal Publising Co. Ltd.

BlueskyMessageWhatsAppEmail

 

image: 

A conceptual diagram demonstrating how subauroral polarization streams (SAPS, right panel) in the subauroral region generate electric fields that map along Earth's magnetic field lines, establishing a vertical polarization electric field in the equatorial ionosphere to modulate the daytime equatorial electrojet (EEJ, left panel).

view more 

Credit: Beijing Zhongke Journal Publishing Co. Ltd.

The equatorial electrojet (EEJ) is an intense, narrow eastward current system flowing within the daytime ionospheric E region (~105–110 km altitude) along the magnetic dip equator. As a crucial component of low-latitude space weather, understanding the EEJ's variability is essential for protecting global communication and navigation networks.  Led by researchers from Wuhan University, this newly published review presents a systematic synthesis of the spatial and temporal evolution of the EEJ. Under geophysically quiet conditions, the EEJ displays pronounced local time and longitudinal variations. Ground and satellite observations demonstrate that while solar photoionization controls its daytime peak near local noon, nonmigrating atmospheric tides originating from tropical tropospheric convection dictate its global wave-4 longitudinal structure.  Beyond quiet-time climatology, the review pays critical attention to the EEJ’s behavior under highly volatile space weather conditions. It delineates how energy inputs from mid- and high-latitude regions can rapidly alter or even reverse the electrojet's direction—creating a westward counter electrojet (CEJ). These perturbations are driven by two main processes: prompt penetration electric fields (PPEF) that map instantly from high latitudes during storms, and disturbance dynamo electric fields (DDEF) driven by long-lasting storm-time thermospheric winds. Other cross-regional factors, such as magnetospheric substorms, sudden changes in solar wind dynamic pressure, subauroral polarization streams (SAPS), and sudden stratospheric warmings (SSWs), are shown to introduce stark asymmetries into low-latitude dynamics.  Furthermore, the review addresses the distinct pathways of solar radiative forcing, such as solar flares and eclipses, which modulate the EEJ through rapid adjustments in ionospheric conductivity and dynamo interactions.  While state-of-the-art physics-based numerical simulations (like the TIEGCM) and data-driven empirical frameworks have successfully reproduced basic seasonal and diurnal structures, their quantitative consistency remains limited during major space weather disturbances. The authors point out critical open issues, including the lack of unified frameworks for multi-factor coupling and the unmodeled nonlinear responses of the ionosphere. Resolving these bottlenecks will require the strategic integration of multi-platform coordinated observations, refined parameterizations of high-latitude boundaries, and data-driven machine learning models.

---

Journal

Earth and Planetary Physics

DOI

10.26464/epp2026055 

Article Title

A review of the climatology features and mid- and high-latitude forcing of the equatorial electrojet