TL;DR
- Solar energy plays an important role in the fight against climate change as a substitute for fossil fuels. Dye-sensitized solar cells promise to be a low-cost supplement to the photovoltaic systems we know today. Their key feature is the dye sensitizers attached to their surface. Researchers continue to improve the performance with sensitizers using iron — a commonly available and environmentally friendly metal.
- Scientists have identified a new process using coordination materials that can accelerate the use of low-cost, Earth-abundant materials with the potential to transform the energy sector by replacing silicone-based solar panels.
- Researchers have developed a new analysis technique that will help scientists improve renewable energy storage by making better supercapacitors.
- Global warming will cause the world’s soil to release carbon, new research shows.
- A new study identifies several keys to sustainably managing the influx of electric vehicle batteries, with an emphasis on battery chemistry, second-life applications and recycling.
- Acetogens are a group of bacteria that can metabolise formate. If these bacteria were manipulated to produce ethanol or lactic acid, a comprehensive circular economy for the GHG CO2 could be realised. To ensure that the process is sustainable, the CO2 is extracted directly from the air and converted to formate using renewable energy.
- Green hydrogen production from solar water splitting has attracted a great interest in recent years because hydrogen is a fuel of high energy density. A research team discovered the quantum confinement effect in a photocatalyst of a 3D-ordered macroporous structure. The quantum confinement effect was found to enable hydrogen production under visible light. The findings offer an option for addressing energy and environmental challenges.
- Researchers use a new model to project where the surge of mismanaged medical waste will end up — including beaches, seabeds, and the Arctic Ocean.
- A new electrocatalyst called a-CuTiaCu converts CO2 into liquid fuels. As reported by researchers, active copper centered on an amorphous copper/titanium alloy produces ethanol, acetone, and n-butanol with high efficiency.
- Net zero carbon is within reach for a major Australian city through comprehensive adoption of photovoltaics in built environment, new modelling has shown.
- And more!
Green Technology Market
Green technology is an applicable combination of advanced tools and solutions to conserve natural resources and environment, minimize or mitigate negative impacts from human activities on the environment, and ensure sustainability development. Green technology is also referred to as clean technology or environmental technology which includes technologies, such as IoT, AI, analytics, blockchain, digital twin, security, and cloud, which collect, integrate, and analyze data from various real-time data sources, such as sensors, cameras, and Global Positioning System (GPS).
Green technology, also known as sustainable technology, protects the environment by using various forms of sustainable energy. Some of the best examples of green technologies include solar panels, LED lighting, wind energy, electric vehicles, vertical farming, and composting.
The global Green Technology and Sustainability market size to grow from USD 11.2 billion in 2020 to USD 36.6 billion by 2025, at a Compound Annual Growth Rate (CAGR) of 26.6% during the forecast period. The growing consumer and industrial interest for the use of clean energy resources to conserve environment and increasing use of Radio Frequency Identification sensors across industries are driving the adoption of green technology and sustainability solutions and services in the market.
The blockchain segment is estimated to grow at the highest CAGR: Energy-intensive cryptocurrency mining has caused a spike in carbon emission, and hence blockchain is capable of driving innovation in the field of green technology.
Latest News
- COP26 Is Over. Now It’s Up To Investors, Companies, And Governments To Raise Their Climate Ambition: Government leaders, policymakers, investors, companies, and sustainability advocates from around the world have emptied out of Glasgow, the site of the COP26 climate conference that wrapped up over the weekend.
- Lessons We Should Learn From COP26: COP26 did not bring much closer to meeting the goal of the Paris Agreement.
- Revealed: The Five Wealthy Nations Whose Climate Words Don’t Match Their Actions: A new report has exposed how five of the world’s wealthiest countries are threatening the ability of the international community to keep climate change targets within reach through their continued support of fossil fuels.
- U.S.-China Climate Pact: Experts Deliver Verdict On ‘Big Deal’ Declaration: Climate experts have given their opinions on a surprise joint climate declaration.
- Global energy storage market set to grow 20X by 2030; will hit 1 TWh: The U.S. and China will lead, claiming over half of the global installations by the end of this decade.
- Powerful Cloud of Greenhouse Gas Spotted Near Russian Pipeline: Methane plume is worst detected in Russia in nearly a month attributed to oil and gas sector in ESA satellite data analyzed by Kayrros.
- Biden Says Infrastructure Bill to Boost U.S.-Built Electric Cars: Biden said the $550 billion infrastructure bill he signed will help propel sales of American-made electric vehicles.
- Israel Looks Next Door to Build Solar Plants And Cut Emissions: Israel is in talks to build solar energy plants in neighboring countries as part of its plans to cut carbon emissions and bolster its green technology sector.
- Deal provides millions to deploy clean energy in New York City: Aiming to deploy clean energy resources, a partnership will unlock $55M for community solar project development.
- How Americans’ Appetite for Leather in Luxury SUVs Worsens Amazon Deforestation: An examination of Brazil’s immense tannery industry shows how hides from illegally deforested ranches can easily reach the global marketplace.
- A Virtual Power Plant In Utah: Coming Soon To A Grid Near You: In January, Utah utility Rocky Mountain Power launched WattSmart Batteries, a new battery energy storage program.
- Green Growth 50: Learning From Companies Boosting Profits While Cutting Emissions: eBay and Aptar are among the U.S. companies that are going green while making green, combining big cuts in GHG emissions with simultaneous growth in profitability.
- How Sport Set The Pace At COP26: From being “5–1 down to climate change” to climate talks being in a “rolling maul”, U.K. PM Boris Johnson had sport on his mind during COP26.
- COP26: Why Addressing Climate Change Requires New Metrics And Women: To address climate change, Dame Ellen MacArthur told the COP26 audience that the economy needs to serve society and nature.
- High Natural Gas Prices Make This The Time To Build Back Better — With Clean Electricity: Natural gas and oil prices are spiking from reduced production, causing financial stress.
- 6 Automakers and 30 Countries Say They’ll Phase Out Gasoline Car Sales: Ford, G.M. and Mercedes agreed to work toward selling only zero-emissions vehicles by 2040.
- A Diesel Engine Giant Pushes Batteries And Hydrogen At COP26 To Combat Climate Crisis: Cummins CEO Tom Linebarger says the heavy-duty vehicle industry needs both options as quickly as possible.
- Toyota’s First Dedicated EV, The BZ4X, Arrives In Spring 2022 With 250-Mile Range: The first purpose-built battery electric vehicle from Toyota is a midsize crossover.
Latest Research
The influence of alkyl chains on the performance of DSCs employing iron(ii) N-heterocyclic carbene sensitizers
by Mariia Becker, Vanessa Wyss, Catherine E. Housecroft, Edwin C. Constable in Dalton Transactions
Solar energy plays an important role in the fight against climate change as a substitute for fossil fuels. Dye-sensitized solar cells promise to be a low-cost supplement to the photovoltaic systems we know today. Their key feature is the dye sensitizers attached to their surface. Researchers at the University of Basel continue to improve the performance with sensitizers using iron — a commonly available and environmentally friendly metal.
Sensitizers are intensely coloured compounds that absorb light and convert its energy into electricity by releasing electrons and “injecting” them into the semiconductor.
So far, the sensitizers used in the dye-sensitized solar cells have either been relatively short-lived or demanded the use of very rare and expensive metals. The holy grail of photovoltaic research is therefore the development of sensitizers using iron — a metal that is both environmentally friendly and the most abundant transition metal on our planet.
For many years, experts considered iron compounds to be unsuitable for these applications because their excited state following light absorption is too short-lived to be of use for energy production. This changed around seven years ago with the discovery of a new class of iron compounds with what are known as N-heterocyclic carbenes (NHCs).
The research group headed by Professor Edwin Constable and Professor Catherine Housecroft at the University of Basel’s Department of Chemistry has been working with these compounds for a number of years. The team led by project leader Dr. Mariia Becker now reports on their results with a sensitizer based on a new family of NHCs.
“We knew that we had to develop materials that would stick to the surface of a semiconductor and whose character would simultaneously allow the arrangement of the functional light-absorbing components on the surface to be optimized,” explains Becker.
The researchers used a two-pronged approach to these challenges: firstly, they incorporated carboxylic acid groups (as found in vinegar) into the iron compound in order to bind it to the semiconductor’s surface. Secondly, they made the compounds “greasy” by adding long carbon chains that made the surface layer more fluid and easier to anchor.
These dye-sensitized solar cell prototypes only achieved overall efficiency of 1 percent, while today’s commercially available solar cells reach around 20 percent efficiency.
“Nevertheless, the results represent a milestone that will encourage further research into these new materials,” says Becker with conviction.
Dynamic dimer copper coordination redox shuttles
by Iacopo Benesperi, Hannes Michaels, Tomas Edvinsson, Michele Pavone, Michael R. Probert, Paul Waddell, Ana Belén Muñoz-García, Marina Freitag in Chem
Technology using a new generation of hybrid solar cells is one step closer to mass-production, thanks to Newcastle University-led research.
An international team of scientists have identified a new process using coordination materials that can accelerate the use of low-cost, Earth-abundant materials with the potential to transform the energy sector by replacing silicone-based solar panels.
The team, led by Newcastle University and colleagues from Uppsala University in Sweden and University of Naples Federico II, Italy, developed dynamic dimeric copper complexes using tetradentate ligands (the ligands that bind four donor atoms). These new copper systems offer a novel combination of fast charge transport in an unprecedented two-electron redox mechanism while inhibiting carrier recombination after disproportionation.
The dynamic dimer system represents a new generation of efficient redox mediators for molecular devices. It can help power photovoltaic devices with minimal voltage losses, with comparably low reorganization energies and recombination rates.
Study co-lead, Dr Marina Freitag, from Newcastle University’s School of Natural and Environmental Sciences, said: “The majority of progress toward the goal of using low-cost and abundant materials has come from improving light-absorbing materials. Charge transfer issues remain a barrier to widespread adoption of this solar technology, and this is the challenge that our research addresses.”
Study co-lead, Prof Ana Belén Muñoz-Garcia, from University of Naples Federico II, said “This work proves that fundamental research combining experiments and theory can provide solid scientific grounds to optimize materials and interfaces for renewable energy technologies with real impact on the society”
A quantitative metabolic analysis reveals Acetobacterium woodii as a flexible and robust host for formate-based bioproduction
by Christian Simon Neuendorf, Gabriel A. Vignolle, Christian Derntl, Tamara Tomin, Katharina Novak, Robert L. Mach, Ruth Birner-Grünberger, Stefan Pflügl in Metabolic Engineering
Acetogens are a group of bacteria that can metabolise formate. For example, they form acetic acid — an important basic chemical. If these bacteria were manipulated to produce ethanol or lactic acid, a comprehensive circular economy for the greenhouse gas CO2 could be realised. To ensure that the process is sustainable, the CO2 is extracted directly from the air and converted to formate using renewable energy.
“The economy of the future must be carbon neutral,” demands Stefan Pflügl. However, since carbon is an important component of many products — such as fuel or plastics — the existing CO2 should be recycled and returned to the cycle. One climate-neutral way to do this is capture CO2 directly from the air and convert it into formate with the help of renewable energy.
This compound of carbon, oxygen and hydrogen can ultimately be a basic building block of the bioeconomy. The advantages of formate are that it is easy to transport and can be used flexibly for the production of chemicals and fuels. These substances can be produced with the help of acetogenic bacteria that feed on carbon compounds and produce acetic acid from them.
In order to use acetogens for the production of raw materials, one needs to understand their metabolism and physiology. Although A. woodii is a model organism, meaning that the bacterium has already been extensively studied, the research team wanted to make a comparative observation. Thus, Stefan Pflügl and his team investigated how substrates such as formate, hydrogen, carbon monoxide, carbon dioxide or fructose affect the metabolism of A. woodii.
“The biggest difference, caused by the different substrates, is the amount of energy that A. woodii gains,” observes Stefan Pflügl. He explains this as follows: “Acetogens are true survival artists that can also metabolise substrates such as CO, CO2 or formate. This is due to the fact that acetogens use what is probably the oldest metabolic pathway for CO2 fixation. Thus, they also manage to produce enough energy to survive under extreme conditions and from alternative food sources.”
This means that acetogens are not only able to utilise CO2 but also do so very efficiently. Consequently, only little energy needs to be expended to convert CO2 into formate, which is then converted into the basic chemical acetic acid.
To exploit the full potential of A. woodii, the researchers also investigated how the bacterium can be genetically modified to produce ethanol or lactic acid instead of acetic acid. While ethanol forms the basis for fuel, lactic acid can be used to produce biodegradable plastics. Oil-based substances could consequently be replaced by more sustainable alternatives.
“Not only would this be in the sense of the bioeconomy, but CO2 and carbon monoxide, which are produced during the combustion of fuel or plastic, could also be recycled to the original product,” Stefan Pflügl envisages.
Exploring the underlying kinetics of electrodeposited PANI‐CNT composite using distribution of relaxation times
by Ash Stott, Décio B. de Freitas Neto, Jose M. Rosolen, Radu A. Sporea, S.Ravi P. Silva in Electrochimica Acta
Researchers from the University of Surrey’s Advanced Technology Institute (ATI) and the University of São Paulo have developed a new analysis technique that will help scientists improve renewable energy storage by making better supercapacitors. The team’s new approach enables researchers to investigate the complex inter-connected behaviour of supercapacitor electrodes made from layers of different materials.
Improvements in energy storage are vital if countries are to deliver carbon reduction targets. The inherent unpredictability of energy from solar and wind means effective storage is required to ensure consistency in supply, and supercapacitors are seen as an important part of the solution. Supercapacitors could also be the answer to charging electric vehicles much faster than is possible using lithium-ion batteries. However, more supercapacitor development is needed to enable them to effectively store enough electricity.
Surrey’s paper explains how the research team used a cheap polymer material called Polyaniline (PANI), which stores energy through a mechanism known as pseudocapacitance. PANI is conductive and can be used as the electrode in a supercapacitor device, storing charge by trapping ions. To maximise energy storage, the researchers have developed a novel method of depositing a thin layer of PANI onto a forest of conductive carbon nanotubes. This composite material makes an excellent supercapacitive electrode, but the fact that it is made up of different materials makes it difficult to separate and fully understand the complex processes which occur during charging and discharging. This is a problem across the field of pseudocapacitor development.
To tackle this problem, the researchers adopted a technique known as the Distribution of Relaxation Times. This analysis method allows scientists to examine complex electrode processes to separate and identify them, making it possible to optimise fabrication methods to maximise useful reactions and reduce reactions that damage the electrode. The technique can also be applied to researchers using different materials in supercapacitor and pseudocapacitor development.
Ash Stott, a postgraduate research student at the University of Surrey who was the lead scientist on the project, said: “The future of global energy use will depend on consumers and industry generating, storing and using energy more efficiently, and supercapacitors will be one of the leading technologies for intermittent storage, energy harvesting and high-power delivery. Our work will help make that happen more effectively.”
Professor Ravi Silva, Director of the ATI and principal author, said: “Following on from world leaders pledging their support for green energy at COP26, our work shows researchers how to accelerate the development of high-performance materials for use as energy storage elements, a key component of solar or wind energy systems. This research brings us one step closer to a clean, cost-effective energy future.”
Second life and recycling: Energy and environmental sustainability perspectives for high-performance lithium-ion batteries
by Yanqiu Tao, Christopher D. Rahn, Lynden A. Archer, Fengqi You in Science Advances
As electric vehicle production revs up across the globe, an inherent consequence will be the mutually growing number of retired lithium-ion batteries that, unlike traditional lead-acid car batteries, are difficult to dispose of.
A new Cornell University-led study identifies several keys to sustainably managing the influx, with an emphasis on battery chemistry, second-life applications and recycling.
“What to do with all these retired electric vehicle batteries is going to be a huge issue,” said Fengqi You, professor in energy systems engineering at Cornell, who used advanced modeling to examine environmental and economic tradeoffs in how batteries are built, used and recycled.
“Lithium-ion batteries are designed today for performance and not for recycling or second life,” said You, noting that electric vehicle batteries typically last five to 12 years before they lose the energy capacity needed to power a vehicle. “There’s very little discussion right now about these environmental dimensions of improving battery design for recycling or reuse.”
One finding is that a battery’s chemistry can affect its overall environmental impact. For instance, cobalt is a common battery material that, when mined, is energy-intensive and damaging to the environment. Replacing cobalt with nickel can alleviate those concerns, but most life cycle scenarios reveal there are tradeoffs.
“Cobalt’s presence, even at relatively small amounts, in a battery cathode leads to a much less oxidative environment for other components, extending the lifespan of the battery and increasing options for second-life use and materials recycling,” said Lynden Archer, dean of engineering at Cornell and co-author of the study. But, Archer said, cobalt’s expense — and association with exploitative child labor — has led the material to be “conventionally thought of as undesirable in the low-cost batteries needed for an ‘electrify-everything’ future.”
The analysis also found that an electric vehicle battery’s overall carbon footprint can be reduced by up to 17% if it can be reused before it is recycled. One choice for battery reuse is power stations that store wind and solar energy. Such energy storage is growing in demand and can make use of retired batteries with reduced energy capacity. And as the share of renewable energy contributing to the power grid grows, a reused battery’s carbon footprint shrinks by around a quarter.
Most of today’s recycling facilities have difficulty breaking apart heavily fortified car batteries and recovering the raw materials within. Yanqiu Tao, a doctoral student who co-authored the study, said policymakers should consider ways to incentivize recycling techniques that optimize the battery’s sustainability.
“In the study we consider the commonly used graphite as the anode-active material, which is hard to recycle and emits carbon dioxide when it’s combusted,” Tao said. “If policymakers can promote graphite separation or emerging recycling methods, it would reduce the environmental impact.”
Prospects of photovoltaic rooftops, walls and windows at a city to building scale
by Maria Panagiotidou, Miguel C. Brito, Kais Hamza, Jacek J. Jasieniak, Jin Zhou in Solar Energy
New modelling, on a scale ranging from individual structures through to neighbourhoods and an entire city, has shown that buildings in the City of Melbourne could provide 74% of their own electricity needs if solar technology is fully integrated into roofs, walls and windows.
The research, led by members of the ARC Centre of Excellence in Exciton Science based at Monash University, together with collaborators at the University of Lisbon, is the first of its kind anywhere in the world to model the viability and impact of window-integrated photovoltaics, alongside other solar technologies, at a city scale.
The results indicate that comprehensive adoption of existing rooftop PV technology alone throughout the city could radically transform Melbourne’s carbon footprint, significantly reducing its reliance on grid electricity generated by burning fossil fuels. Further gains could be made through the widespread deployment of emerging, highly efficient ‘solar windows’ and photovoltaic technology integrated in building facades.
The researchers hope that by using the modelling they have developed, policy makers, energy providers, construction companies and building owners will be able to optimise the PV potential of both new and existing structures. The researchers compared Melbourne’s 2018 electricity consumption to the electricity production that could potentially be achieved through fully and widely building-integrated solar. Consumption data from Melbourne’s CBD was obtained from Jemena, CitiPower & Powercor distribution companies and was accessed through the independent Victorian research body, the Centre for New Energy Technologies (C4NET).
At city-scale modelling, they found that photovoltaics could provide 74% of Melbourne’s building consumption needs. Rooftop solar would constitute 88% of this supply, with wall-integrated and window-integrated solar delivering 8% and 4% respectively.
Wall and window-integrated solar technology was shown to suffer less of a reduction in efficiency during winter months relative to rooftop solar, delivering more consistent year-round benefits and value. The potential contribution of window-integrated solar rose to 18% at the neighbourhood scale, reflecting high building heights and window to wall ratios.
The researchers determined the annual solar radiation on Melbourne’s building surfaces to identify suitable areas for PV installation, taking into account technical limitations and cost factors.
Detailed modelling enabled the incident solar radiation and PV potential of the urban areas to be simulated. A large range of factors had to be taken into consideration, including the impact of shadows casted by shading systems and balconies, as well as the performance characteristics of the various solar technologies. Among other techniques, correlation and linear regression analysis were performed to identify the interdependency between urban form indicators and the annual PV potential. The total area featured in the study is the 37.4 km2 area of central Melbourne, of which 35.1km2 was built floor area in 2019, consisting primarily of residential and commercial buildings.
The results showed that the photovoltaics potential of this area is driven mainly by the possibility of adding further rooftop solar. While blocks with high rooftop and wall solar potential are found across the city, the highest potential for window-integrated solar gains is in the city’s high-density urban centres, such as the central business district.
“By using photovoltaic technology commercially available today and incorporating the expected advances in wall and window-integrated solar technology over the next ten years, we could potentially see our CBD on its way to net zero in the coming decades,” said lead author Professor Jacek Jasieniak.
“We began importing coal-fired power from the LaTrobe Valley in the 1920s to stop the practice of burning smog-inducing coal briquettes onsite to power our CBD buildings, and it’s now feasible that over one hundred years later, we could see a full circle moment of Melbourne’s buildings returning to local power generation within the CBD, but using clean, climate-safe technologies that help us meet Australia’s Net Zero 2050 target.”
Co-author Dr Jenny Zhou: “Although there’s plenty of policies supporting energy-efficiency standards for new buildings, we’re yet to see a substantial response to ensuring our existing buildings are retrofitted to meet the challenges of climate change. Our research provides a framework that can help decision-makers move forward with implementing photovoltaic technologies that will reduce our cities’ reliance on damaging fossil fuels.”
Ultrastable Cu Catalyst for CO 2 Electroreduction to Multicarbon Liquid Fuels by Tuning C–C Coupling with CuTi Subsurface
by Fei Hu, Li Yang, Yawen Jiang, Chongxiong Duan, Xiaonong Wang, Longjiao Zeng, Xuefeng Lv, Delong Duan, Qi Liu, Tingting Kong, Jun Jiang, Ran Long, Yujie Xiong in Angewandte Chemie International Edition
A new electrocatalyst called a-CuTi@Cu converts carbon dioxide (CO2 ) into liquid fuels. As reported by a team of Chinese researchers, active copper centered on an amorphous copper/titanium alloy produces ethanol, acetone, and n-butanol with high efficiency.
Most of our global energy demands are still being met by burning fossil fuels, which contributes to the greenhouse effect through the release of CO2 . To reduce global warming, we must look for opportunities to use CO2 as a raw material for basic chemicals. Through electrocatalytic conversion of CO2 using renewable energy, a climate-neutral, artificial carbon cycle could be established. Excess energy produced by photovoltaics and wind energy could be stored through the electrocatalytic production of fuels from CO2. These could then be burned as needed. Conversion into liquid fuels would be advantageous because they have high energy density and are safe to store and transport. However, the electrocatalytic formation of products with two or more carbon atoms (C2+) is very challenging.
A team from Foshan University (Foshan, Guangdong), the University of Science and Technology of China (Hefei, Anhui), and Xi’an Shiyou University (Xi’an, Shaanxi), led by Fei Hu, Tingting Kong, Jun Jiang, and Yujie Xiong has now developed a novel electrocatalyst that efficiently converts CO2 to liquid fuels with multiple carbon atoms (C2–4). The primary products are ethanol, acetone, and n-butanol.
To make the electrocatalyst, thin ribbons of a copper/titanium alloy are etched with hydrofluoric acid to remove the titanium from the surface. This results in a material named a-CuTi@Cu, with a porous copper surface on an amorphous CuTi alloy. It has catalytically active copper centers with remarkably high activity, selectivity, and stability for the reduction of CO2 to C2+ products (total faradaic efficiency of about 49 % at 0.8 V vs. reversible hydrogen electrode for C2–4, and it is stable for at least three months). In contrast, pure copper foil produces C1 products but hardly any C2+ products.
The reaction involves a multistep electron-transfer process via various intermediates. In the new electrocatalyst, the inactive titanium atoms below the surface actually play an important role; they increase the electron density of the Cu atoms on the surface. This stabilizes the adsorption of *CO, the key intermediate in the formation of multicarbon products, allows for high coverage of the surface with *CO, and lowers the energy barrier for di- and trimerization of the *CO as new carbon-carbon bonds are formed.
Temperature effects on carbon storage are controlled by soil stabilisation capacities
by Iain P. Hartley, Tim C. Hill, Sarah E. Chadburn & Gustaf Hugelius in Nature Communications
Global warming will cause the world’s soil to release carbon, new research shows.
Scientists used data on more than 9,000 soil samples from around the world, and found that carbon storage “declines strongly” as average temperatures increase. This is an example of a “positive feedback,” where global warming causes more carbon to be released into the atmosphere, further accelerating climate change. Importantly, the amount of carbon that could be released depends on the soil type, with coarse-textured (low-clay) soils losing three times as much carbon as fine-textured (clay-rich) soils.
The researchers, from the University of Exeter and Stockholm University, say their findings help to identify vulnerable carbon stocks and provide an opportunity to improve Earth System Models (ESMs) that simulate future climate change.
“Because there is more carbon stored in soils than there is in the atmosphere and all the trees on the planet combined, releasing even a small percentage could have a significant impact on our climate,” said Professor Iain Hartley of Exeter’s College of Life and Environmental Sciences. “Our analysis identified the carbon stores in coarse-textured soils at high-latitudes (far from the Equator) as likely to be the most vulnerable to climate change.
“Such stores, therefore, may require particular attention given the high rates of warming taking place in cooler regions. “In contrast, we found carbon stores in fine-textured soils in tropical areas to be less vulnerable to climate warming.”
The data on the 9,300 soil profiles came from the World Soil Information database, with the study focusing on the top 50cm of soil. By comparing carbon storage in places with different average temperatures, the researchers estimated the likely impact of global warming. For every 10°C of increase in temperature, average carbon storage (across all soils) fell by more than 25%.
“Even bleak forecasts do not anticipate this level of warming, but we used this scale to give us confidence that the effects we observed were caused by temperature rather than other variables,” Professor Hartley said. “Our results make it clear that, as temperatures rise, more and more carbon is release from soil. “It’s important to note that our study did not examine the timescales involved, and further research is needed to investigate how much carbon could be released this century.”
The researchers found that their results could not be represented by an established ESM.
“This suggests that there is an opportunity to use the patterns we have observed to improve how models represent soils, and further reduce uncertainty in their projections,” Professor Hartley said.
The differences in carbon storage based on soil texture occur because finer soils provide more mineral surface area for carbon-based organic material to bond to, reducing the ability of microbes to access and decompose it.
Plastic waste release caused by COVID-19 and its fate in the global ocean
by Yiming Peng, Peipei Wu, Amina T. Schartup, Yanxu Zhang in Proceedings of the National Academy of Sciences
Around the world, the COVID-19 pandemic has led to an increased demand for single-use plastics such as face masks, gloves, and face shields. The resulting waste, some of which ends up in rivers and oceans, is intensifying pressure on an already out-of-control global plastic problem. While many researchers suspect there will be a massive influx of COVID-related mismanaged plastic waste, a new study is the first to project the magnitude and fate of the waste in the oceans.
Led by a team of researchers at Nanjing University’s School of Atmospheric Sciences and UC San Diego’s Scripps Institution of Oceanography, the study uses a newly developed ocean plastic numerical model to quantify the impact of the pandemic on plastic discharge from land sources. Graduate students Yiming Peng and Peipei Wu of Nanjing University led the research.
Using the model, the researchers found that more than eight million tons of pandemic-associated plastic waste have been generated globally, with more than 25,000 tons entering the global ocean. Within three to four years, a significant portion of this ocean plastic debris is expected to make its way onto either beaches or the seabed. A smaller portion will go into the open ocean, eventually to be trapped in the centers of ocean basins or subtropical gyres, which can become garbage patches, and a circumpolar plastic accumulation zone in the Arctic Ocean.
The researchers incorporated data from the start of the pandemic in 2020 through August 2021, finding that most of the global plastic waste entering the ocean is coming from Asia, with hospital waste representing the bulk of the land discharge. The study reveals the need for better management of medical waste in developing countries.
“When we started doing the math, we were surprised to find that the amount of medical waste was substantially larger than the amount of waste from individuals, and a lot of it was coming from Asian countries, even though that’s not where most of the COVID-19 cases were,” said study co-author Amina Schartup, an assistant professor at Scripps Oceanography. “The biggest sources of excess waste were hospitals in areas already struggling with waste management before the pandemic; they just weren’t set up to handle a situation where you have more waste.”
Devised by the research team, the Nanjing University MITgcm-plastic model (NJU-MP) used in this study works like “a virtual reality,” explained Yanxu Zhang, the corresponding author and a professor at the School of Atmospheric Sciences at Nanjing University. He said the model was built based on Newton’s laws of motion and the law of conservation of mass.
“The model simulates how the seawater moves driven by wind and how the plastics float on the surface ocean, degraded by sunlight, fouled by plankton, landed on beaches, and sunk to the deep,” said Zhang. “It can be used to answer ‘what if’ questions, for example, what will happen if we add a certain amount of plastics to the ocean?”
The study highlights the hotspot rivers and watersheds that require special attention in plastic waste management. The researchers found that most of the global plastic waste from the pandemic is entering the ocean from rivers. Asian rivers account for 73 percent of the total discharge of plastics, with the top three contributors being the Shatt al-Arab, Indus, and Yangtze rivers, which discharge into the Persian Gulf, Arabian Sea, and East China Sea. European rivers account for 11 percent of the discharge, with minor contributions from other continents.
While most of the pandemic-associated plastics are expected to settle on beaches and the seafloor, a smaller amount will likely end up circulating or settling in the Arctic Ocean, which study authors say appears to be a “dead-end” for plastic debris transported into it due to ocean circulation patterns.
“There is a pretty consistent circulation pattern in the ocean, and that’s why we can build models that replicate how the ocean moves — it’s just physical oceanography at this point,” said Schartup, whose research normally focuses on understanding mercury in the oceans. “We know that if waste is released from Asian rivers into the North Pacific Ocean, some of that debris will likely end up in the Arctic Ocean — a kind of a circular ocean which can be a bit like an estuary, accumulating all kinds of things that get released from the continents.”
The model shows that about 80 percent of the plastic debris that transits into the Arctic Ocean will sink quickly, and a circumpolar plastic accumulation zone is modeled to form by 2025.
The Arctic ecosystem is already considered to be particularly vulnerable due to the harsh environment and high sensitivity to climate change. The potential ecological impacts of exposure to accumulated Arctic plastics adds another layer of concern, said the researchers.
To combat the influx of plastic waste into the oceans, the authors urge for better management of medical waste in epicenters, especially in developing countries. They also called for global public awareness of the environmental impact of personal protection equipment (PPE) and other plastic products, and the development of innovative technologies for better plastic waste collection, classification, treatment, and recycling, and development of more environmentally friendly materials.
“Indeed, the COVID-related plastic is only a portion of a bigger problem we face in the 21st century: plastic waste,” said Zhang. “To solve it requires a lot of technical renovation, transition of economy, and change of lifestyle.”
Unveiling Carrier Dynamics in Periodic Porous BiVO4 Photocatalyst for Enhanced Solar Water Splitting
by Hao Wu, Rowshanak Irani, Kunfeng Zhang, Lin Jing, Hongxing Dai, Hoi Ying Chung, Fatwa F. Abdi, Yun Hau Ng in ACS Energy Letters
Green hydrogen production from solar water splitting has attracted a great deal of interest in recent years because hydrogen is a fuel of high energy density. A research team co-led by scholars from City University of Hong Kong (CityU) and Germany discovered the quantum confinement effect in a photocatalyst of a 3D-ordered macroporous structure. The quantum confinement effect was found to enable hydrogen production under visible light. The findings offer an option for addressing energy and environmental challenges. The research was co-led by Dr Ng Yun Hau, Associate Professor in CityU’s School of Energy and Environment (SEE), and researchers from Germany.
Dr Ng, an expert in photocatalysis research, pointed out that the typical photocatalyst for solar water splitting can absorb ultraviolet light only from the solar spectrum, which accounts for about 4% of the energy from sunlight. In contrast, bismuth vanadate (BiVO4), a metal oxide photocatalyst responsive to both ultraviolet and visible light, can absorb up to 30% of the energy in the solar spectrum.
BiVO4 in a 3D-ordered macroporous (3DOM) structure has received considerable attention owing to its superior performance. The improved photocatalytic activities of this structure are often attributed to the larger surface area, high light absorption, and suppressed charge recombination.
However, there were no systematic studies that correlate the influence of the charge transport of highly ordered porous nanostructure on photoactivity. Dr Ng and his team took on this challenge and investigated the distinct carrier dynamics of 3DOM and plate-like BiVO4 samples, as well as their efficiency in photocatalysis.
The team discovered that in the water-splitting process under visible light, the amount of oxygen produced by the 3DOM BiVO4 photocatalyst is almost two times that produced by the plate-like BiVO4. Furthermore, the 3DOM BiVO4 photocatalyst exhibited a higher anodic photocurrent density than the plate-like form. Therefore, 3DOM BiVO4 has higher photocatalysis efficiency.
“To our surprise, BiVO4, originally an oxygen-producing photocatalyst, also produced hydrogen during water splitting under visible light when it was in the 3DOM structure. This had never previously been reported,” said Dr Ng.
How can BiVO4 in a 3DOM structure produce hydrogen? Dr Wu Hao, the first author of the paper, who is the energy stream leader in Dr Ng’s laboratory, shared one of the highlights of this study. “We discovered that quantum confinement arising from the ultrathin, crystalline wall of 3DOM BiVO4 raised its conduction band. It enables photocatalytic proton reduction to hydrogen under visible-light illumination, allowing hydrogen to be generated from water splitting.” Quantum confinement refers to changes in electronic and optical properties such as energy levels and band gaps when the size of the material is reduced to the nanoscale.
“BiVO4 in general cannot produce hydrogen because of its position of the conduction band. Now thanks to the quantum confinement effect, which raised its conduction band, hydrogen can be produced. This is also the first time that quantum confinement effect was found in 3DOM BiVO4,” Dr Ng explained.
The research team also discovered that even without using a co-catalyst, 3DOM BiVO4 can still produce hydrogen from solutions under visible-light illumination, while the plate-like BiVO4 showed only negligible hydrogen production. A co-catalyst is a substance that facilitates the function of a catalyst. It can provide accumulating sites for photo-generated charges and promote charge separation.
The team also applied advanced techniques, including time-resolved microwave conductivity, to investigate BiVO4 photocatalyst in 3DOM and plate-like structures. They discovered that compared with the plate-like structure, 3DOM BiVO4 has about six times higher charge mobility, about 18 times longer charge carrier lifetime, and about nine times longer effective diffusion length, thus enhancing the efficiency of photocatalysis.
This study represents a fundamental step in understanding charge transport in metal oxide semiconductors and highly ordered porous structure.
The next goal of Dr Ng and his team is to split wastewater and explore methods to scale up photocatalytic systems.
“Hydrogen produced from solar water splitting is a green process without any carbon emissions,” said Dr Ng. “Hydrogen can be used for industrial purposes and in fuel cells for electricity. We expect this technology to have a wider application in the future, as there is high demand for producing hydrogen from green resources.”
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