GT/ Unlocking the power of photosynthesis for clean energy production
Energy & green technology biweekly vol.49, 2nd May — 18th May
TL;DR
- Researchers are embarking on a groundbreaking project to mimic the natural process of photosynthesis using bacteria to deliver electrons to a nanocrystal semiconductor photocatalyst. By leveraging the unique properties of microorganisms and nanomaterials, the system has the potential to replace current approaches that derive hydrogen from fossil fuels, revolutionizing the way hydrogen fuel is produced and unlocking a powerful source of renewable energy.
- Small bats are bad at converting energy into muscle power. Surprisingly, a new study led by Lund University in Sweden reveals that this ability increases the faster they fly.
- Researchers develop a new method for the sustainable use of carbon dioxide.
- Photovoltaics, the conversion of light to electricity, is a key technology for sustainable energy. Since the days of Max Planck and Albert Einstein, we know that light as well as electricity are quantized, meaning they come in tiny packets called photons and electrons. In a solar cell, the energy of a single photon is transferred to a single electron of the material, but no more than one. Only a few molecular materials like pentacene are an exception, where one photon is converted to two electrons instead. Researchers have now deciphered the first step of this process by recording an ultrafast movie of the photon-to-electricity conversion process, resolving a decades-old debate about the mechanism of the process.
- Perovskite solar cells (PVSCs) are a promising alternative to traditional silicon-based solar cells because of their high power-conversion efficiency and low cost. However, one of the major challenges in their development has been achieving long-term stability. Recently, a research team made a breakthrough by developing an innovative multifunctional and non-volatile additive which can improve the efficiency and stability of perovskite solar cells by modulating perovskite film growth. This simple and effective strategy has great potential for facilitating the commercialization of PVSCs.
- A team led by LMU chemist Lena Daumann has demonstrated for the first time that bacteria can use certain radioactive elements to sustain their metabolism.
- Discarded or drifting in the ocean, plastic debris can accumulate on the water’s surface, forming floating islands of garbage. Although it’s harder to spot, researchers suspect a significant amount also sinks. In a new study, team used computer modeling to study how far bits of lightweight plastic travel when falling into the Mediterranean Sea. Their results suggest these particles can drift farther underwater than previously thought.
- A team of researchers at Aalto University has developed a new tool to help urban planners keep urban developments in line with climate goals. The tool provides a metric that planners can use to improve carbon-neutral planning of urban growth, which is essential for meeting carbon emission targets.
- New research found that Americans already bearing the brunt of climate change and health inequities are most at risk of impact by a lengthy power outage.
- Researchers confirm the superiority of seawater batteries that use chelating agents.
- 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 Research
Shewanella oneidensis MR-1 respires CdSe quantum dots for photocatalytic hydrogen evolution
by Emily H. Edwards, Jana Jelušić, Ryan M. Kosko, Kevin P. McClelland, Soraya S. Ngarnim, Wesley Chiang, Sanela Lampa-Pastirk, Todd D. Krauss, Kara L. Bren in Proceedings of the National Academy of Sciences
As the world faces an increasing demand for clean and sustainable energy sources, scientists are turning to the power of photosynthesis for inspiration. With the goal of developing new, environmentally friendly techniques to produce clean-burning hydrogen fuel, a team of researchers at the University of Rochester is embarking on a groundbreaking project to mimic the natural process of photosynthesis using bacteria to deliver electrons to a nanocrystal semiconductor photocatalyst.
In a paper, Kara Bren, the Richard S. Eisenberg Professor in Chemistry at Rochester, and Todd Krauss, a professor of chemistry, demonstrate that thebacteria Shewanella oneidensisoffer an effectively free, yet efficient, way to provide electrons to their artificial photosynthesis system. By leveraging the unique properties of these microorganisms along with nanomaterials, the system has the potential to replace current approaches that derive hydrogen from fossil fuels, revolutionizing the way hydrogen fuel is produced and unlocking a powerful source of renewable energy.
“Hydrogen is definitely a fuel of high interest for the DOE right now,” Bren says. “If we can figure out a way to efficiently extract hydrogen from water, this could lead to an incredible amount of growth in clean energy.”
Hydrogen is “an ideal fuel,” Bren says, “because it’s environmentally-friendly and a carbon-free alternative to fossil fuels.”
Hydrogen is the most abundant element in the universe and can be produced from a variety of sources, including water, natural gas, and biomass. Unlike fossil fuels, which produce greenhouse gases and other pollutants, when hydrogen is burned, the only byproduct is water vapor. Hydrogen fuel also has a high energy density, which means it contains a lot of energy per unit of weight. It can be used in a variety of applications, including fuel cells, and can be made on both small and large scales, making it feasible for everything from home use to industrial manufacturing.
Despite hydrogen’s abundance, there is virtually no pure hydrogen on Earth; it is almost always bound to other elements, such as carbon or oxygen, in compounds like hydrocarbons and water. To use hydrogen as a fuel source, it must be extracted from these compounds. Scientists have historically extracted hydrogen either from fossil fuels, or, more recently, from water. To achieve the latter, there is a major push to employ artificial photosynthesis.
During natural photosynthesis, plants absorb sunlight, which they use to power chemical reactions to convert carbon dioxide and water into glucose and oxygen. In essence, light energy is converted into chemical energy that fuels the organism. Similarly, artificial photosynthesis is a process of converting an abundant feedstock and sunlight into a chemical fuel. Systems that mimic photosynthesis require three components: a light absorber, a catalyst to make the fuel, and a source of electrons. These systems are typically submerged in water, and a light source provides energy to the light absorber. The energy allows the catalyst to combine the provided electrons together with protons from the surrounding water to produce hydrogen gas. Most of the current systems, however, rely on fossil fuels during the production process or don’t have an efficient way to transfer electrons.
“The way hydrogen fuel is produced now effectively makes it a fossil fuel,” Bren says. “We want to get hydrogen from water in a light-driven reaction so we have a truly clean fuel — and do so in a way that we don’t use fossil fuels in the process.”
Krauss’s group and Bren’s group have been working for about a decade to develop an efficient system that employs artificial photosynthesis and utilizes semiconductor nanocrystals for light absorbers and catalysts. One challenge the researchers faced was figuring out a source of electrons and efficiently transferring the electrons from the electron donor to the nanocrystals. Other systems have used ascorbic acid, commonly known as vitamin C, to deliver electrons back to the system. While vitamin C might seem inexpensive, “you need a source of electrons that is almost free or the system becomes too expensive,” Krauss says.
In their paper, Krauss and Bren report on an unlikely electron donor: bacteria. They found that Shewanella oneidensis, bacteria first gathered from Lake Oneida in upstate New York, offers an effectively free, yet efficient, way to provide electrons to their system. While other labs have combined nanostructures and bacteria, “all of those efforts are taking electrons from the nanocrystals and putting them into the bacteria, then using the bacterial machinery to prepare fuels,” Bren says. “As far as we know, ours is the first case to go the opposite way and use the bacteria as an electron source to a nanocrystal catalyst.”
When bacteria grow under anaerobic conditions — conditions without oxygen — they respire cellular substances as fuel, releasing electrons in the process. Shewanella oneidensis can take electrons generated by its own internal metabolism and donate them to the external catalyst.
Bren envisions that, in the future, individual homes could potentially have vats and underground tanks to harness the power of the sun to produce and store small batches of hydrogen, allowing people to power their homes and cars with inexpensive, clean-burning fuel. Bren notes there are currently trains, buses, and cars powered by hydrogen fuel cells but almost all the hydrogen that is available to power these systems comes from fossil fuels.
“The technology’s out there,” she says, “but until the hydrogen’s coming from water in a light-driven reaction — without using fossil fuels — it isn’t really helping the environment.”
Conversion efficiency of flight power is low, but increases with flight speed in the migratory bat Pipistrellus nathusii
by Shannon E. Currie, L. Christoffer Johansson, Cedric Aumont, Christian C. Voigt, Anders Hedenström in Proceedings of the Royal Society B: Biological Sciences
Small bats are bad at converting energy into muscle power. Surprisingly, a new study led by Lund University reveals that this ability increases the faster they fly.
The researchers have studied the efficiency of migratory bats — a species that weighs about eight grams and is found in almost all of Europe. Efficiency, in this case, is the ability to convert supplied energy into something we need. For bats and birds, it’s the energy required to fly. In a new study, a research team in Lund states that the efficiency varies with the bats’ flight speed. The faster the bats flew, the more energy they managed to convert into muscle power.
“Previously, we have believed that efficiency is a constant. So this is a bit of a breakthrough,” says Anders Hedenström, biology researcher at Lund University.
Using high-speed cameras, laser and smoke in a wind tunnel, the researchers have measured the bat’s kinetic energy. They have then compared these results with the animals’ metabolism — a methodological breakthrough with technically advanced measurements. In the past, researchers have only measured either kinetic energy or metabolic rate and compared this to theories.
“Our study reveals that the efficiency is lower than expected in this small migratory bat, but that it increases with flight speed,” says Anders Hedenström.
The bat’s ability to convert food into energy in flight controls the ability to produce a forward and upward force to overcome air resistance and gravity. This is what is known as metabolic energy. How efficiently animals use metabolic energy during flight has previously been assumed to be the same at all speeds.
“Until now, the calculations have greatly underestimated the “flight costs” of the migratory bat, which has made it difficult to predict their migratory behaviour. Our results provide a new basis for studying their behaviour,” says Anders Hedenström.
The researchers’ new discovery helps us to better understand the migratory behaviour of these mysterious bats. Compared to bird migrations, bat migrations are not as well mapped.
“We have previously analysed the blackcap, a bird which also migrates. The bird’s efficiency was 20 percent compared to the bat’s ten percent. This means that of all the energy the bat consumes, only ten percent is useful, while it’s 20 percent for the blackcap. The bat thus uses the energy less efficiently. The difference may be because birds only have two flight muscles, while bats have about 15 muscles for the same job,” says Anders Hedenström.
Engineering a new-to-nature cascade for phosphate-dependent formate to formaldehyde conversion in vitro and in vivo
by Maren Nattermann, Sebastian Wenk, Pascal Pfister, et al in Nature Communications
New synthetic metabolic pathways for fixation of carbon dioxide could not only help to reduce the carbon dioxide content of the atmosphere, but also replace conventional chemical manufacturing processes for pharmaceuticals and active ingredients with carbon-neutral, biological processes. A new study demonstrates a process that can turn carbon dioxide into a valuable material for the biochemical industry via formic acid.
In view of rising greenhouse gas emissions, carbon capture, the sequestration of carbon dioxide from large emission sources, is an urgent issue. In nature, carbon dioxide assimilation has been taking place for millions of years, but its capacity is far from sufficient to compensate human-made emissions.
Researchers led by Tobias Erb at the Max Planck Institute for Terrestrial Microbiology are using nature’s toolbox to develop new ways of carbon dioxide fixation. They have now succeeded in developing an artificial metabolic pathway that produces the highly reactive formaldehyde from formic acid, a possible intermediate product of artificial photosynthesis. Formaldehyde could be fed directly into several metabolic pathways to form other valuable substances without any toxic effects. As in the natural process, two primary components are required: Energy and carbon. The former can be provided not only by direct sunlight but also by electricity — for example from solar modules.
Within the added-value chain, the carbon source is variable. carbon dioxide is not the only option here, all monocarbons (C1 building blocks) come into question: carbon monoxide, formic acid, formaldehyde, methanol and methane. However, almost all of these substances are highly toxic — either to living organisms (carbon monoxide, formaldehyde, methanol) or to the planet (methane as a greenhouse gas). Only formic acid, when neutralised to its base formate, is tolerated by many microorganisms in high concentrations.
“Formic acid is a very promising carbon source,” emphasizes Maren Nattermann, first author of the study. “But converting it to formaldehyde in the test tube is quite energy-intensive.” This is because the salt of formic acid, formate, cannot be converted easily into formaldehyde. “There’s a serious chemical barrier between the two molecules that we have to bridge with biochemical energy — ATP — before we can perform the actual reaction.”
The researcher’s goal was to find a more economical way. After all, the less energy it takes to feed carbon into metabolism, the more energy remains to drive growth or production. But such a path does not exist in nature. “It takes some creativity to discover so-called promiscuous enzymes with multiple functions,” says Tobias Erb. “However, the discovery of candidate enzymes is only the beginning. We’re talking about reactions that you can count along with since they’re so slow — in some cases, less than one reaction per second per enzyme. Natural reactions can happen a thousand times faster.” This is where synthetic biochemistry comes in, says Maren Nattermann: “If you know an enzyme’s structure and mechanism, you know where to intervene. Here, we benefit significantly from the preliminary work of our colleagues in basic research.”
The optimization of the enzymes comprised of several approaches: building blocks were specifically exchanged, and random mutations were generated and selected for capability.
“Formate and formaldehyde are both wonderfully suited because they penetrate cell walls. We can put formate into the culture medium of cells that produce our enzymes, and after a few hours convert the formaldehyde produced into a non-toxic yellow dye,” explains Maren Nattermann.
The result would not have been possible in such a short time without the use of high-throughput methods. To achieve this, the researchers cooperated with their industrial partner Festo, based in Esslingen, Germany.
“After about 4000 variants, we achieved a fourfold improvement in production,” says Maren Nattermann. “We have thus created the basis for the model mikrobe Escherichia coli, the microbial workhorse of biotechnology, to grow on formic acid. For now, however, our cells can only produce formaldehyde, not convert it further.”
Orbital-resolved observation of singlet fission
by Alexander Neef, Samuel Beaulieu, Sebastian Hammer, Shuo Dong, Julian Maklar, Tommaso Pincelli, R. Patrick Xian, Martin Wolf, Laurenz Rettig, Jens Pflaum, Ralph Ernstorfer in Nature
Photovoltaics, the conversion of light to electricity, is a key technology for sustainable energy. Since the days of Max Planck and Albert Einstein, we know that light as well as electricity are quantized, meaning they come in tiny packets called photons and electrons. In a solar cell, the energy of a single photon is transferred to a single electron of the material, but no more than one. Only a few molecular materials like pentacene are an exception, where one photon is converted to two electrons instead.
“When pentacene is excited by light, the electrons in the material rapidly react,” explains Prof. Ralph Ernstorfer, a senior author of the study. “It was an open and very disputed question whether a photon excites two electrons directly or initially one electron, which subsequently shares its energy with another electron.”
To unravel this mystery the researchers used time- and angle-resolved photoemission spectroscopy, a cutting-edge technique to observe the dynamics of electrons on the femtosecond time scale, which is a billionth of a millionth of a second. This ultrafast electron movie camera enabled them to capture images of the fleeting excited electrons for the first time.
“Seeing these electrons was crucial to decipher the process,” says Alexander Neef, from the Fritz Haber Institute and the first author of the study. “An excited electron not only has a specific energy but also moves in distinct patterns, which are called orbitals. It is much easier to tell the electron apart if we can see their orbital shapes and how these change over time.”
With the images from the ultrafast electron movie at hand, the researchers decomposed the dynamics of the excited electrons for the first time based on their orbital characteristics. “We can now say with certainty that only one electron is excited directly and identified the mechanism of the excitation-doubling process,” adds Alexander Neef.
Knowing the mechanism of exciton fission is essential to using it for photovoltaic applications. A silicon solar cell enhanced with an excitation-doubling material could boost the solar-to-electricity efficiency by one-third. Such an advance could have enormous impacts since solar energy will be the dominant power source of the future. Already today large investments are flowing into the construction of these third-generation solar cells.
Hydrogen-bond-bridged intermediate for perovskite solar cells with enhanced efficiency and stability
by Fengzhu Li, Xiang Deng, Zhangsheng Shi, Shengfan Wu, Zixin Zeng, Deng Wang, Yang Li, Feng Qi, Zhuomin Zhang, Zhengbao Yang, Sei-Hum Jang, Francis R. Lin, Sai‐Wing Tsang, Xian-Kai Chen, Alex K.-Y. Jen in Nature Photonics
Perovskite solar cells (PVSCs) are a promising alternative to traditional silicon-based solar cells because of their high power-conversion efficiency and low cost. However, one of the major challenges in their development has been achieving long-term stability. Recently, a research team from City University of Hong Kong (CityU) made a breakthrough by developing an innovative multifunctional and non-volatile additive which can improve the efficiency and stability of perovskite solar cells by modulating perovskite film growth. This simple and effective strategy has great potential for facilitating the commercialisation of PVSCs.
“This type of multifunctional additive can be generally used to make different perovskite compositions for fabricating highly efficient and stable perovskite solar cells. The high-quality perovskite films will enable the upscaling of large-area solar panels,” explained Professor Alex Jen Kwan-yue, Lee Shau Kee Chair Professor of Materials Science and Director of the Hong Kong Institute for Clean Energy at CityU, who led the study.
PVSCs have attracted significant attention due to their impressive solar power conversion efficiency (PCE). Since perovskites can be deposited from solutions onto the fabrication surfaces, PVSCs have the potential to be applied in building-integrated photovoltaics (BIPV), wearable devices, and solar farm applications. However, the efficiency and stability are still affected by the severe energy loss associated with defects embedded at the interfaces and grain boundaries of the perovskites. Therefore, the intrinsic quality of perovskite film plays a critical role in determining the achievable efficiency and stability of PVSCs.
Although many previous research studies have focused on improving the film morphology and quality with volatile additives, these additives tend to escape from the film after annealing, creating a void at the perovskite-substrate interface. To tackle these issues, the CityU researchers developed a simple but effective strategy of modulating the perovskite film growth to enhance the film quality. They found that by adding a multifunctional molecule (4-guanidinobenzoic acid hydrochloride, (GBAC)) to the perovskite precursor, a hydrogen-bond-bridged intermediate phase is formed and modulates the crystallization to achieve high-quality perovskite films with large perovskite crystal grains and coherent grain growth from the bottom to the surface of the film. This molecule can also serve as an effective defect passivation linker (a method to reduce the defect density of perovskite film) in the annealed perovskite film due to its non-volatility, resulting in significantly reduced non-radiative recombination loss and improved film quality.
Their experiments showed that the defect density of perovskite films can be significantly reduced after introducing GBAC. The power conversion efficiency of inverted (p-i-n) perovskite solar cells based on the modified perovskites was boosted to 24.8% (24.5% certified by the Japan Electrical Safety & Environment Technology Laboratories), which is among the highest values reported in the literature. Also, the overall energy loss of the device was reduced to 0.36eV, representing one of the lowest energy losses among the PVSC devices with high power conversion efficiency. Additionally, the unencapsulated devices exhibit improved thermal stability beyond 1,000 hours under continuous heating at 65 ± 5°C in a nitrogen-filled glovebox while maintaining 98% of the original efficiency.
The team demonstrated the general applicability of this strategy for different perovskite compositions and large-area devices. For example, a larger area device (1 cm2) in the experiment delivered a high PCE of 22.7% with this strategy, indicating excellent potential for fabricating scalable, highly efficient PVSCs.
“This work provides a clear path to achieving optimised perovskite film quality to facilitate the development of highly efficient and stable perovskite solar cells and their upscaling for practical applications,” said Professor Jen.
In the future, the team aims to further extend the molecular structures and optimize the device structure through compositional and interfacial engineering. They will also focus on the fabrication of large-area devices.
Minor Actinides Can Replace Essential Lanthanides in Bacterial Life
by Helena Singer, Robin Steudtner, Andreas S. Klein, Carolin Rulofs, Cathleen Zeymer, Björn Drobot, Arjan Pol, N. Cecilia Martinez‐Gomez, Huub J. M. Op den Camp, Lena J. Daumann in Angewandte Chemie International Edition
A team led by LMU chemist Lena Daumann has demonstrated for the first time that bacteria can use certain radioactive elements to sustain their metabolism.
As well as being a useful material in all kinds of key technologies, lanthanides are important for bacteria, which use the rare earth metals in their metabolism. It turns out, however, that they are not as irreplaceable as previously thought, as an international and interdisciplinary team led by Professor Lena Daumann from the Department of Chemistry at LMU has demonstrated: Certain bacteria can use the radioactive elements americium and curium instead of the lanthanides — and even prefer them sometimes.
Bacteria that use lanthanides are widespread in the environment. They belong to the so-called methylotrophs, which can use methanol or methane as carbon and energy sources. To do this, they take up lanthanides and incorporate them into an important metabolic enzyme, a lanthanide-dependent methanol dehydrogenase. The elements americium and curium, members of the radioactive actinides, are very similar to the lanthanides when it comes to key chemical properties such as size and charge. “And so we asked ourselves whether the bacteria can use actinides instead of their essential lanthanides,” says Daumann.
Now the researchers have demonstrated that this is actually the case. They carried out an in-vivo study of two methylotrophic bacterial strains in collaboration with the Helmholtz Center in Dresden-Rossendorf (HZDR). “We fed the microbes various elements and showed that they incorporate americium and curium and grow just as well with these elements,” explains Daumann. It is important that the actinides have the same oxidation state and are of a similar size to the lanthanides normally used, so that they fit in the active center of methanol dehydrogenase. Additional in-vitro studies with isolated methanol dehydrogenase also demonstrate that the enzyme works with the actinides and exhibits similar activities.
“We could thus show for the first time that organisms can use these radioactive elements for life processes,” emphasizes Daumann. When the bacteria were offered a mixture of various lanthanides and actinides, they even preferred americium and curium ahead of some lanthanides. The ability of the bacteria to incorporate radioactive actinides is also interesting with respect to potential applications: “Methylotrophic bacteria could potentially be used in bioremediation or in the separation and recycling of lanthanides and actinides. Such difficult-to-separate mixtures are often found in spent nuclear fuel,” says Daumann.
Low-Density Plastic Debris Dispersion beneath the Mediterranean Sea Surface
by Alberto Baudena, Rainer Kiko, Isabel Jalón-Rojas, Maria Luiza Pedrotti in Environmental Science & Technology
Discarded or drifting in the ocean, plastic debris can accumulate on the water’s surface, forming floating islands of garbage. Although it’s harder to spot, researchers suspect a significant amount also sinks. In a new study, one team used computer modeling to study how far bits of lightweight plastic travel when falling into the Mediterranean Sea. Their results suggest these particles can drift farther underwater than previously thought.
From old shopping bags to water bottles, plastic pollution is besieging the oceans. Not only is this debris unsightly, animals can become trapped in it or mistakenly eat it. And if it remains in the water, plastic waste can release organic pollutants. The problem is most visible on the surface, where currents can aggregate this debris into massive, so-called garbage patches. However, plastic waste also collects much deeper. Even material that weighs less than water can sink as algae and other organisms glom onto it, and through other processes. Bits of this light plastic, which typically measure 5 millimeters or less, have turned up at least half a mile below the surface. Researchers don’t know much about what happens when plastic sinks, but they generally assume it falls straight down from the surface. However, Alberto Baudena and his colleagues suspected this light plastic might not follow such a direct route.
To test this assumption, they used an advanced computer model developed to track plastic at sea and incorporated extensive data already collected on floating plastic pollution in the Mediterranean Sea. They then simulated nearly 7.7 million bits of plastic distributed across the sea and tracked their virtual paths to depths as great as about half a mile. Their results suggested that the slower the pieces sank, the farther currents carried them from their points of origin, with slowest traveling an average of roughly 175 miles laterally. While observations of the distribution of plastic underwater are limited, the team found their simulations agree with those available in the Mediterranean. Their simulations also suggested that currents may push plastic toward coastal areas and that only about 20% of pollution near coasts originates from the nearest country. These particles’ long journeys mean this plastic has greater potential to interact with, and harm, marine life, according to the researchers.
Can future cities grow a carbon storage equal to forests?
by Ilmari Talvitie, Antti Kinnunen, Ali Amiri, Seppo Junnila in Environmental Research Letters
A team of researchers at Aalto University has developed a new tool to help urban planners keep urban developments in line with climate goals. The tool provides a metric that planners can use to improve carbon-neutral planning of urban growth, which is essential for meeting carbon emission targets.
Urban growth commonly encroaches on forested areas and agricultural land. This means that cities consume carbon sinks as they grow, which makes it harder for municipalities and countries to reach the net-zero emissions targets that are vital to avoid a climate catastrophe. The new metric, called the carbon storage (CS) factor, reflects how much carbon can be captured in planned urban developments.
The CS factor enables urban planners to evaluate how a new development will affect the city’s carbon balance. By comparing the amount of storage capacity lost (for example, from deforestation) with the CS factor of development plans that use different approaches and technologies, planners can ensure that urban development maintains or even restores the region’s natural carbon storage capacity.
‘There are many tools available to increase the CS factor. Increasing wooden construction is a good option in some regions, but it’s also possible to store carbon in the soil using biochar and other tools, or to include new fast-growing plants in the landscape, or even through direct carbon capture and storage technologies. We hope planners will adopt this mindset and use the CS factor to help them plan sustainable urban growth,’ says Aalto Professor Seppo Junnila, who led the study.
The researchers used the CS factor to evaluate how wooden construction in Finland’s capital region could compensate for deforestation from urban growth. They found that using the right kind of wooden construction technologies would mean that as much as 70% of future construction could preserve the lost forest’s carbon storage capacity. This would require using methods that store significant amounts of carbon, such as log or cross-laminated timber. The study also showed that similar results could be obtained using wooden construction elsewhere in Europe, Asia and Oceania. However, the researchers stress that increased wooden construction is only a sustainable choice if forests are sustainably managed.
‘Our goal isn’t to encourage cities to expand into new areas but to provide planners with tools to mitigate the impact of development on carbon storage when forest clearing is unavoidable,’ says Junnila.
Spatiotemporal distribution of power outages with climate events and social vulnerability in the USA.
by Vivian Do, Heather McBrien, Nina M. Flores, Alexander J. Northrop, Jeffrey Schlegelmilch, Mathew V. Kiang, Joan A. Casey in Nature Communications
Joan Casey lived through frequent wildfire-season power outages when she lived in northern California. While waiting for the power to return, she wondered how the multi-day blackouts affected a community’s health.
“For me it was an inconvenience, but for some people it could be life-threatening,” said Casey, now an assistant professor in the University of Washington’s Department of Environmental and Occupational Health Sciences. “If you had an uncle that had an electric heart pump, basically, his heart wouldn’t work without power. You could use a backup battery for eight hours, but after that, if you don’t have access to electricity, you have to go to the emergency room. This is a really dangerous situation.”
Years later, Casey has answers. A study analyzed three years of power outages across the U.S., finding that Americans already bearing the brunt of climate change and health inequities are clustered in four regions — Louisiana, Arkansas, central Alabama and northern Michigan — and that they are most at risk of impact by a lengthy blackout. The findings could help shape the future of local energy infrastructure, especially as climate change intensifies and the American power grid continues to age. Last year’s Inflation Reduction Act included billions of dollars to revamp energy systems, and Casey hopes federal agencies will consult the newly published findings to target energy upgrades.
The study is the first county-level analysis of power outages, which the federal government reports only at the state level. That poses a problem for researchers: a federally reported outage in Washington state could occur in Seattle, Spokane, or somewhere in between, making it difficult to understand specifically which population is affected. Casey and her team found that between 2018 and 2020, more than 231,000 power outages lasting more than an hour occurred nationwide. Of those, 17,484 stretched at least eight hours — a duration widely viewed as medically relevant.
Most counties that experienced an electrical outage had at least one event lasting more than eight hours. These counties were most concentrated in the South, Northeast and Appalachia. Next, researchers looked at how power outages overlapped with severe weather. They wanted to know which weather events are most likely to cause an outage, and which parts of the U.S. are most often hit with a blackout-causing storm.
They found that heavy precipitation in a given area makes a power outage five times more likely. Tropical cyclones, storms with high winds that originate over tropical oceans, make a power outage 14 times more likely. And a tropical cyclone with heavy precipitation on a hot day — like the hurricanes that each fall hit the Gulf Coast? They make power outages 52 times more likely.
“We look at weather reports and decide whether or not to bring an umbrella or stay home,” Casey said. “But thinking about being prepared for an outage when one of these events is rolling through is a new element to consider.”
Then came questions of equity. Incorporating a combination of socioeconomic and medical factors, Casey’s team identified communities that would likely be especially vulnerable during a long power outage. Using that data, the researchers were able to identify communities that experienced both high social vulnerability and frequent power outages. A map of those counties shows a bright cluster in Louisiana and Arkansas, with more clusters in central Alabama and northern Michigan. In those places especially, the country’s inevitable change in energy infrastructure provides the greatest opportunity to improve public health.
“Any time we can identify another factor that we can intervene on to get closer to health equity, it’s exciting,” Casey said. “I think we’re going to see tremendous change, especially in the way our energy systems are set up, in the next couple decades. It’s this huge opportunity to get equity into every conversation and talk about what we’re going to do to make two decades from now look different from where we are.”
Effects of chelating agent on the nanostructure of nickel hexacyanoferrate and its performance in seawater battery application
by Hyebin Jeong, Sang Hyun Ahn, Changshin Jo in Chemical Engineering Journal
Water blankets around 70 percent of the Earth’s surface. Moreover, 97 percent of all the water on earth is seawater, which is impotable because of its salt content. But what if we could harness its potential as a new source of renewable energy?
Recently, a research team led by Professor Changshin Jo (Graduate Institute of Ferrous & Energy Materials Technology (GIFT), Department of Chemical Engineering) and Ph.D. candidate Hyebin Jeong (Chemical Engineering) at POSTECH has made strides in this area by confirming the superior performance of seawater batteries (SWBs) that incorporate chelating agents.
Lithium-ion batteries have become ubiquitous in portable electronic devices and automotive batteries. However, they are not without limitations, as they present a risk of explosion and may become unusable if lithium supplies are depleted. To address these challenges, the development of next-generation batteries is currently underway. Among them, seawater batteries represent a promising option that utilizes Na-ions found in seawater to generate energy. These batteries offer the distinct advantage of easy resource accessibility and are environmentally friendly, as they require no separate treatment processes.
The high salinity of seawater can be attributed to the presence of Na-ions, which are utilized by seawater batteries to generate and store electrical energy as they move back and forth between the cathode and anode. However, one of the challenges in suing nickel hexacyanoferrate (NiHCF) as an intercalation cathode material for SWBs is the high occurrence of defects during fabrication. To address this issue, the research team synthesize NiHCF with a chelating agent (Sample A) and compared its performance with untreated NiHCF (Sample B) to evaluate the effectiveness of the chelating agent.
A look at the two samples under a microscope reveals the striking difference in their shape and structure. Sample B consists of randomly aggregated nanosized primary particles to form micro-level particles, whereas Sample A comprises individual 200–300 nanometer-sized cubic-shaped particles. Although the individual particle size of Sample B is smaller, it is less advantageous for battery production due to the aggregation of multiple particles into larger cohesive structures.
The researchers additionally assessed the electrochemical performance of both samples. Firstly, they measured the water content, and it was found that Sample A had lower water content than Sample B did. Generally, higher water content tends to impede electrochemical performance. Furthermore, measurements of current and voltage showed that Sample A had high energy efficiency and capacity.
The research team achieved a groundbreaking feat by performing 2,000 cycles of charging and discharging on batteries using two samples, where Sample A demonstrated a remarkable capacity retention rate of approximately 92.8%. Furthermore, the defect generation rate, a previous drawback of NiHCF, was observed to decrease to 6% in Sample A.
The results of the study demonstrate the superior performance achieved by adding a chelating agent to nickel hexacyanoferrate and using this as a cathode material in seawater batteries. This discovery can promote the development of seawater batteries as a promising candidate for next-generation energy storage systems.
