GT/ Ultrathin solar cells promise improved satellite performance
Energy & green technology biweekly vol.37, 4th November — 18th November
TL;DR
- As low Earth orbit becomes more cluttered, it becomes increasingly necessary to use middle Earth orbits, and radiation-tolerant cell designs will be needed. Making photovoltaics thinner should increase their longevity because the charge carriers have less far to go during their shortened lifetimes. Scientists propose a radiation-tolerant photovoltaic cell design that features an ultrathin layer of light-absorbing material. Compared to thicker cells, nearly 3.5 times less cover glass is needed for the ultra-thin cells to deliver the same amount of power after 20 years of operation.
- Researchers have found a way to improve the performance of silicon photovoltaic (PV) or solar cells. This is done through the addition of ‘passivating contacts’ between the metal and silicon parts of the solar cell, making it more productive.
- A simple material can separate carbon dioxide from other gases that fly out of the smokestacks of coal-fired power plants. It lacks the shortcomings that other proposed carbon filtration materials have, rivaling designer compounds in its simplicity, overall stability and ease of preparation.
- A new method to treat sewage can efficiently convert leftover sludge to biogas, an advance that could help communities lower their waste treatment costs while helping the environment.
- It is possible to capture carbon dioxide from the surrounding atmosphere and repurpose it into useful chemicals usually made from fossil fuels, according to a new study.
- Every green leaf is able to convert solar energy into chemical energy, storing it in chemical compounds. However, an important sub-process of photosynthesis can already be technically imitated — solar hydrogen production: Sunlight generates a current in a so-called photoelectrode that can be used to split water molecules. This produces hydrogen, a versatile fuel that stores solar energy in chemical form and can release it when needed.
- Researchers have reviewed conventional assumptions for the transport of plastic in rivers. The actual amount of plastic waste in rivers could be up to 90 percent greater than previously assumed. The new findings should help improve monitoring and remove plastic from water bodies.
- A study has found evidence that the evolution of tree roots over 300 million years ago triggered mass extinction events through the same chemical processes created by pollution in modern oceans and lakes.
- Scientists have successfully bioengineered an important protein in plants to increase the yield of oil from their fruits and seeds — a holy grail for the global agri-food industry. Their patent-pending method can increase oil content in seeds by 15 to 18 per cent, which is a significant improvement since major oil-producing crops such as soybean, sunflower, rapeseed, and peanut, already have a high percentage of oil in their seeds. This innovation can help the world in its quest for sustainability, helping to reduce the amount of arable land needed for oil-yielding crops while increasing the yield to meet the world’s growing demand for vegetable oil.
- Space missions already use electric propulsion devices, where electromagnetic fields are utilized to generate the thrust of spacecraft. One such electrodeless device, which harnesses radio frequency (rf) to generate plasma and a magnetic nozzle (MN) to channel and accelerate plasma, has shown immense promise in pushing the boundaries of space travel. But scientists have so far failed to achieve efficient conversion of the rf power to thrust energy. Now, a researcher has achieved a stunning 30% conversion efficiency.
- 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
Radiation effects in ultra-thin GaAs solar cells
by A. Barthel, L. Sayre, G. Kusch, R. A. Oliver, L. C. Hirst in Journal of Applied Physics
Most space satellites are powered by photovoltaic cells that convert sunlight to electricity. Exposure to certain types of radiation present in orbit can damage the devices, degrading their performance and limiting their lifetime.
Scientists from the University of Cambridge proposed a radiation-tolerant photovoltaic cell design that features an ultrathin layer of light-absorbing material.
When solar cells absorb light, they transfer its energy to negatively charged electrons in the material. These charge carriers are knocked free and generate a flow of electricity across the photovoltaic. Irradiation in space causes damage and lowers efficiency by displacing atoms in the solar cell material and reducing the lifetime of the charge carriers. Making photovoltaics thinner should increase their longevity because the charge carriers have less far to go during their shortened lifetimes.
As low Earth orbit becomes more cluttered with satellites, it becomes increasingly necessary to use middle Earth orbits, such as the Molniya orbit that passes through the center of Earth’s proton radiation belt. Radiation-tolerant cell designs will be needed for these higher orbits.
Another application for radiation-tolerant cells is the study of other planets and moons. For example, Europa, a moon of Jupiter, has one of the most severe radiation environments in the solar system. Landing a solar-powered spacecraft on Europa will require radiation-tolerant devices.
The investigators built two types of photovoltaic devices using the semiconductor gallium arsenide. One was an on-chip design built by layering several substances in a stack. The other design involved a silver back mirror to enhance light absorption.
To mimic the effects of radiation in space, the devices were bombarded with protons generated at the Dalton Cumbrian Nuclear Facility in the U.K. The performance of the photovoltaic devices before and after irradiation was studied using a technique known as cathodoluminescence that can give a measure of the amount of radiation damage. A second set of tests using a Compact Solar Simulator were carried out to determine how well the devices converted sunlight to power after being bombarded with protons.
“Our ultra-thin solar cell outperforms the previously studied, thicker devices for proton radiation above a certain threshold. The ultra-thin geometries offer favorable performance by two orders of magnitude relative to previous observations,” said author Armin Barthel.
The authors said that the improved performance of these ultra-thin cells is because the charge carriers live long enough to travel between terminals in the device.
Compared to thicker cells, nearly 3.5 times less cover glass is needed for the ultra-thin cells to deliver the same amount of power after 20 years of operation. This will translate to a lighter load and significant reduction in launch costs.
Outstanding Surface Passivation for Highly Efficient Silicon Solar Cells Enabled by Innovative Al y TiO x /TiO x
by Mohamed M. Shehata, Pheng Phang, Rabin Basnet, Yanting Yin, Felipe Kremer, Gabriel Bartholazzi, Gunther G. Andersson, Daniel H. Macdonald, Lachlan E. Black in Solar RRL
An increase in the efficiency of solar panels may be on the horizon, as research from The Australian National University (ANU) reduces their current limitations.
ANU researchers have found a way to improve the performance of silicon photovoltaic (PV) or solar cells. This is done through the addition of ‘passivating contacts’ between the metal and silicon parts of the solar cell, making it more productive.
“These findings will help push the performance of silicon solar cells closer to their theoretical limit,” Mohamed Ismael, lead ANU researcher and PhD candidate said. “Each day, the sun produces significantly more energy than needed to power the whole planet. The only limitation is our ability to economically convert it to electricity,” he said.
Solar cells are devices that convert light energy in the form of photons into electrical energy. As it stands, solar cells aren’t operating at their maximum capacity due to substantial electrical losses associated with the direct contact of metals with silicon.
“Transition metal oxides such as titanium oxide have many qualities that make them ideal as passivating contact layers,” Dr Lachlan Black said. “This isn’t a new idea, but the way in which we combined these layers has produced better results and higher operating voltages than anything previously reported.”
The research team is hoping to develop the technology to a point where it can be applied to industrial solar cells on a large scale. The PV market is a multi-billion-dollar industry, with silicon solar cells contributing to 95 per cent of all commercial solar cells. They are predicted to remain dominant for the foreseeable future given their advantageous properties compared to competitors.
“If successful, we could see our technology in almost all new solar panels installed on your roof or utility-scale solar plants,” Dr Black said.
Some practical issues still need to be addressed before the technology can be implemented, but the PV community is already working to solve these challenges.
“Improving the efficiency of solar cells guarantees more clean energy at a reduced cost. This not only helps to address climate change, but opens up new economic opportunities for this low-cost clean energy,” Ismael said.
Aluminum formate, Al(HCOO) 3 An earth-abundant, scalable, and highly selective material for CO 2 capture
by Hayden A. Evans, Dinesh Mullangi, Zeyu Deng, Yuxiang Wang, Shing Bo Peh, Fengxia Wei, John Wang, Craig M. Brown, Dan Zhao, Pieremanuele Canepa, Anthony K. Cheetham in Science Advances
How can we remove carbon dioxide, a greenhouse gas, from fossil-fuel power plant exhaust before it ever reaches the atmosphere? New findings suggest a promising answer lies in a simple, economical and potentially reusable material analyzed at the National Institute of Standards and Technology (NIST), where scientists from several institutions have determined why this material works as well as it does.
The team’s object of study is aluminum formate, one of a class of substances called metal-organic frameworks (MOFs). As a group, MOFs have exhibited great potential for filtering and separating organic materials — often the various hydrocarbons in fossil fuels — from one another. Some MOFs have shown promise at refining natural gas or separating the octane components of gasoline; others might contribute to reducing the cost of plastics manufacturing or cheaply converting one substance to another. Their capacity to perform such separations comes from their inherently porous nature.
Aluminum formate, which the scientists refer to as ALF, has a talent for separating carbon dioxide (CO2) from the other gases that commonly fly out of the smokestacks of coal-fired power plants. It also lacks the shortcomings that other proposed carbon filtration materials have, said NIST’s Hayden Evans, one of the lead authors of the team’s research paper.
“What makes this work exciting is that ALF performs really well relative to other high-performing CO2 adsorbents, but it rivals designer compounds in its simplicity, overall stability and ease of preparation,” said Evans, a chemist at the NIST Center for Neutron Research (NCNR). “It is made of two substances found easily and abundantly, so creating enough ALF to use widely should be possible at very low cost.”
The research team includes scientists from the National University of Singapore; Singapore’s Agency for Science, Technology and Research; the University of Delaware; and the University of California, Santa Barbara.
Coal-fired power plants account for roughly 30% of global CO2 emissions. Even as the world embraces other energy sources such as solar and wind power that do not generate greenhouse gases, finding a way to reduce the carbon output of existing plants could help mitigate their effects while they remain in operation.
Scrubbing the CO2 from flue gas before it reaches the atmosphere in the first place is a logical approach, but it has proved challenging to create an effective scrubber. The mixture of gases that flows up the smokestacks of coal-fired power plants is typically fairly hot, humid and corrosive — characteristics that have made it difficult to find an economical material that can do the job efficiently. Some other MOFs work well but are made of expensive materials; others are less costly in and of themselves but perform adequately only in dry conditions, requiring a “drying step” that reduces the gas humidity but raises the overall cost of the scrubbing process.
“Put it all together, you need some kind of wonder material,” Evans said. “Here, we’ve managed to tick every box except stability in very humid conditions. However, using ALF would be inexpensive enough that a drying step becomes a viable option.”
ALF is made from aluminum hydroxide and formic acid, two chemicals that are abundant and readily available on the market. It would cost less than a dollar per kilogram, Evans said, which is up to 100 times less expensive than other materials with similar performance. Low cost is important because carbon capture at a single plant could require up to tens of thousands of tons of filtration material. The amount needed for the entire world would be enormous.
On a microscopic scale, ALF resembles a three-dimensional wire cage with innumerable small holes. These holes are just large enough to allow CO2 molecules to enter and get trapped, but just small enough to exclude the slightly larger nitrogen molecules that make up the majority of flue gas. Neutron diffraction work at the NCNR showed the team how the individual cages in the material collect and fill with CO2, revealing that the gas molecules fit inside certain cages within ALF like a hand in a glove, Evans said.
Despite its potential, ALF is not ready for immediate use. Engineers would need to design a procedure to create ALF at large scales. A coal-fired plant would also need a compatible process to reduce the humidity of the flue gas before scrubbing it. Evans said that a great deal is already understood about how to address these issues, and that they would not make the cost of using ALF prohibitive.
What to do with the CO2 afterward is also a major question, he said, though this is a problem for all carbon-capture materials. There are research efforts underway to convert it to formic acid — which is not only a naturally occurring organic material but also one of the two constituents of ALF. The idea here is that ALF could become part of a cyclic process where ALF removes CO2 from the exhaust streams, and that captured CO2 is used to create more formic acid. This formic acid would then be used to make more ALF, further reducing the overall impact and cost of the material cycle.
“There is a great deal of research going on nowadays into the problem of what to do with all the captured CO2,” Evans said. “It seems possible that we could eventually use solar energy to split hydrogen from water, and then combine that hydrogen with the CO2 to make more formic acid. Combined with ALF, that’s a solution that would help the planet.”
Influence of Excess Charge on Water Adsorption on the BiVO4(010) Surface
by Wennie Wang, Marco Favaro, Emily Chen, Lena Trotochaud, Hendrik Bluhm, Kyoung-Shin Choi, Roel van de Krol, David E. Starr, Giulia Galli in Journal of the American Chemical Society
Every green leaf is able to convert solar energy into chemical energy, storing it in chemical compounds. However, an important sub-process of photosynthesis can already be technically imitated — solar hydrogen production: Sunlight generates a current in a so-called photoelectrode that can be used to split water molecules. This produces hydrogen, a versatile fuel that stores solar energy in chemical form and can release it when needed.
At the HZB Institute for Solar Fuels, many teams are working on this vision. The focus of their research is on producing efficient photoelectrodes. These are semiconductors that remain stable in aqueous solutions and are highly active: Not only can they convert sunlight into electrical current, but they may also act as catalysts to accelerate the splitting of water. Among the best candidates for inexpensive and efficient photoelectrodes is bismuth vanadate (BiVO4).
“Basically, we know that just by immersing bismuth vanadate in the aqueous solution the chemical composition of the surface changes,” says Dr. David Starr of the HZB Institute for Solar Fuels. And his colleague Dr. Marco Favaro adds: “Although there are a great many studies on BiVO4, it has not been clear until now exactly what implications this has on the surface electronic properties once they come into contact with the water molecules.” In this work, they have now investigated this question.
They studied single crystals of BiVO4 doped with molybdenum under water vapor with resonant ambient pressure photoemission spectroscopy at the Advanced Light Source at Lawrence Berkeley National Laboratory. A team led by Giulia Galli at the University of Chicago then performed density functional theory calculations to help interpret the data and to untangle the contributions of individual elements and electron orbitals to the electronic states.
“In situ resonant photoemission has allowed us to understand how the electronic properties of our BiVO4 crystals changed upon water adsorption,” Favaro says. The combination of measurements and calculations showed that due to excess charge, generated by either doping or defects on certain surfaces of the crystal, so-called polarons may form: negatively charged localized states, where water molecules can easily attach and then dissociate. The hydroxyl groups formed via water dissociation help to stabilize further polaron formation. “The excess electrons are localized as polarons at VO4 units on the surface,” Starr summarizes the results.
“What we can’t yet assess for sure is what role the polarons play in charge transfer. Whether they promote it and thus increase efficiency or, on the contrary, are an obstacle, we still need to figure that out,” Starr admits. The results provide valuable insights into processes that modify the surface chemical composition and electronic structure and might foster the knowledge-based design of better photoanodes for green hydrogen production.
Improved valorization of sewage sludge in the circular economy by anaerobic digestion: Impact of an innovative pretreatment technology
by Nalok Dutta, Anthony T. Giduthuri, Muhammand Usman Khan, Richard Garrison, Birgitte K. Ahring in Waste Management
A new method to treat sewage can efficiently convert leftover sludge to biogas, an advance that could help communities lower their waste treatment costs while helping the environment.
Washington State University research team tested a pretreatment technology, adding an extra step to typical treatments and using oxygen-containing high pressure steam to break down sewage sludge. They found that they were able to convert more than 85% of the organic material to biogas, which can be used to produce electricity or upgraded to renewable natural gas (RNG) for the natural gas grid or for local use. Adding the new pretreatment step improves the anaerobic conversion of sewage sludge at the wastewater treatment facility from the current less-than-50% conversion rate, and they produced 98% more methane overall compared to current practice.
“It was shown to be extremely efficient, and that’s very exciting,” said Birgitte Ahring, professor in the Gene and Linda Voiland School of Chemical Engineering and Bioengineering, who led the work. “This can be applicable and something we could begin to explore in Washington state. Not wasting waste but using its potential instead has major advantages.”
Sewage sludge is not a sought-after product. About half of the wastewater treatment plants in the U.S. use anaerobic digestion to reduce this waste, but the process, in which microbes break down the waste, is inefficient. The leftover sludge, called biosolids, generally ends up in landfills. Wastewater treatment facilities also use large amounts of electricity to clean up municipal wastewater. They are often the largest user of electricity in a small community.
“If they could make their own electricity or for some of the large plants, make renewable natural gas and add it to the natural gas grid, then they can reduce the use of fossil fuels. Here we are beginning to move into the idea of the circular economy,” said Ahring, who is also a faculty member in the Bioproducts, Sciences, and Engineering Laboratory at WSU Tri-cities.
For their study, the WSU research team treated the sludge at high temperature and pressure with oxygen added before the anaerobic digestion process. The small amount of oxygen under the high-pressure conditions acts as a catalyst breaks down the polymers in the material. The WSU researchers have been studying this pretreatment process for several years, using it to break down straw and woody materials. They weren’t sure the process would work with the different composition of sewage sludge, such as lipids and proteins, but were positively surprised.
“This is not a very high-tech solution,” Ahring said. “It’s actually a solution that can be useful even at small scale. The efficiency has to be high or else you cannot warrant adding the extra costs to the process.”
The technology could be particularly helpful for smaller communities, many of which are motivated to reduce waste and their climate impact, she added.
Feasibility of switchable dual function materials as a flexible technology for CO2 capture and utilisation and evidence of passive direct air capture
by Loukia-Pantzechroula Merkouri, Tomas Ramirez Reina, Melis S. Duyar in Nanoscale
It is possible to capture carbon dioxide (CO2) from the surrounding atmosphere and repurpose it into useful chemicals usually made from fossil fuels, according to a study from the University of Surrey.
The technology could allow scientists to both capture CO2 and transform it into useful chemicals such as carbon monoxide and synthetic natural gas in one circular process. Dr Melis Duyar, Senior Lecturer of Chemical Engineering at the University of Surrey commented:
“Capturing CO2 from the surrounding air and directly converting it into useful products is exactly what we need to approach carbon neutrality in the chemicals sector. This could very well be a milestone in the steps needed for the UK to reach its 2050 net-zero goals.
“We need to get away from our current thinking on how we produce chemicals, as current practices rely on fossil fuels which are not sustainable. With this technology we can supply chemicals with a much lower carbon footprint and look at replacing fossil fuels with carbon dioxide and renewable hydrogen as the building blocks of other important chemicals.”
The technology uses patent-pending switchable Dual Function Materials (DFMs), that capture carbon dioxide on their surface and catalyse the conversion of captured CO2 directly into chemicals. The “switchable” nature of the DFMs comes from their ability to produce multiple chemicals depending on the operating conditions or the composition of the added reactant. This makes the technology responsive to variations in demand for chemicals as well as availability of renewable hydrogen as a reactant. Dr Duyar continued:
“These outcomes are a testament to the research excellence at Surrey, with continuously improving facilities, internal funding schemes and a collaborative culture.”
Loukia-Pantzechroula Merkouri, Postgraduate student leading this research at the University of Surrey added:
“Not only does this research demonstrate a viable solution to the production of carbon neutral fuels and chemicals, but it also offers an innovative approach to combat the ever-increasing CO2 emissions contributing to global warming.”
The key role of surface tension in the transport and quantification of plastic pollution in rivers
by Daniel Valero, Biruk S. Belay, Antonio Moreno-Rodenas, Matthias Kramer, Mário J. Franca in Water Research
Whether in drinking water, food or even in the air: plastic is a global problem — and the full extent of this pollution may go beyond of what we know yet. Researchers at the Karlsruhe Institute of Technology (KIT), together with partners from the Netherlands and Australia, have reviewed conventional assumptions for the transport of plastic in rivers. The actual amount of plastic waste in rivers could be up to 90 percent greater than previously assumed. The new findings should help improve monitoring and remove plastic from water bodies.
Rivers play a key role in the transport of plastic in the environment. “As soon as plastic enters a river, it is transported rapidly and can spread throughout the environment,” says Dr Daniel Valero from the Institute of Water and River Basin Management at KIT and lead author of a new study on plastic transport.
“But, depending on its size and material, plastic can behave very differently in the process. It can sink, be suspended in the water, remain afloat or be stopped by obstacles.” Current methods for estimating plastic pollution in rivers, however, are mainly based on surface observations. “This is the only way to effectively monitor large rivers from bridges. However, what happens under the water surface has not been sufficiently verified so far,” says Valero.
Together with his research partners, Valero now investigated the behaviour of over 3,000 particles in the size range from 30 millimetres to larger objects such as plastic cups in flowing waters. In laboratory models, each individual particle was tracked in 3D with millimetre precision using a multi-camera system, whereby the entire water column — from the water surface to the bottom — was recorded. With this experiment, the researchers were able to statistically prove that plastic particles behave very differently depending on exactly where they are located in a river. Plastic that is transported below the water surface behaves as predicted by common models for turbulent flows.
“The particles are dispersed like dust in the wind” says Valero. As soon as plastic emerges the water surface, however, the situation changes radically: “On contact with the water surface, the particles are caught by the surface tension like flies in a spider’s web. Then they cannot escape easily.” This adhesive effect is just as relevant for surface transport in rivers as the specific buoyancy of a plastic particle.
On the one hand, the results of the experiment show that it is not enough to consider only floating plastic on the surface to estimate the amount of plastic in rivers.
“The bias is significant. If the turbulent character of the transport of plastic particles under the water surface is not considered, then the amount of plastic waste in rivers can be underestimated by up to 90 percent,” says Daniel Valero.
On the other hand, the results confirm that existing knowledge about the behaviour of particles in turbulent flows is relevant for the transport of plastic in rivers and that it can help to estimate the total amount more realistically. To this end, the researchers have quantified the ratio between concentrations of plastic particles at the water surface and at greater depths with different transport conditions. On this basis, monitoring can still be carried out by visual observation of the water surface and the actual transported quantity can be calculated relatively accurately. In addition, the results can help in a very practical way, namely in the development of new approaches for plastic removal: “If you can estimate where the most plastic is, then you also know where a clean-up is most effective,” says Valero.
Enhanced terrestrial nutrient release during the Devonian emergence and expansion of forests: Evidence from lacustrine phosphorus and geochemical records
by Matthew S. Smart, Gabriel Filippelli, William P. Gilhooly III, John E.A. Marshall, Jessica H. Whiteside in GSA Bulletin
The evolution of tree roots may have triggered a series of mass extinctions that rocked the Earth’s oceans during the Devonian Period over 300 million years ago, according to a study led by scientists at IUPUI, along with colleagues in the United Kingdom.
Evidence for this new view of a remarkably volatile period in Earth’s pre-history is reported. The study was led by Gabriel Filippelli, Chancellor’s Professor of Earth Sciences in the School of Science at IUPUI, and Matthew Smart, a Ph.D. student in his lab at the time of the study.
“Our analysis shows that the evolution of tree roots likely flooded past oceans with excess nutrients, causing massive algae growth,” Filippelli said. “These rapid and destructive algae blooms would have depleted most of the oceans’ oxygen, triggering catastrophic mass extinction events.”
The Devonian Period, which occurred 419 million to 358 million years ago, prior to the evolution of life on land, is known for mass extinction events, during which it’s estimated nearly 70 percent of all life on Earth perished. The process outlined in the study — known scientifically as eutrophication — is remarkably similar to modern, albeit smaller-scale, phenomenon currently fueling broad “dead zones” in the Great Lakes and the Gulf of Mexico, as excess nutrients from fertilizers and other agricultural runoff trigger massive algae blooms that consume all of the water’s oxygen. The difference is that these past events were likely fueled by tree roots, which pulled nutrients from the land during times of growth, then abruptly dumped them into the Earth’s water during times of decay.
The theory is based upon a combination of new and existing evidence, Filippelli said. Based upon a chemical analysis of stone deposits from ancient lake beds — whose remnants persist across the globe, including the samples used in the study from sites in Greenland and off the northeast coast of Scotland — the researchers were able to confirm previously identified cycles of higher and lower levels of phosphorus, a chemical element found in all life on Earth. They were also able to identify wet and dry cycles based upon signs of “weathering” — or soil formation — caused by root growth, with greater weathering indicating wet cycles with more roots and less weathering indicating dry cycles with fewer roots.
Most significantly, the team found the dry cycles coincided with higher levels of phosphorus, suggesting dying roots released their nutrients into the planet’s water during these times.
“It’s not easy to peer over 370 million years into the past,” said Smart. “But rocks have long memories, and there are still places on Earth where you can use chemistry as a microscope to unlock the mysteries of the ancient world.”
In light of the phosphorus cycles occurring at the same time as the evolution of the first tree roots — a feature of Archaeopteris, also the first plant to grow leaves and reach heights of 30 feet — the researchers were able to pinpoint the decay of tree roots as the prime suspect behind the Devonian Periods extinction events. Fortunately, Filippelli said, modern trees don’t wreak similar destruction since nature has since evolved systems to balance out the impact of rotting wood. The depth of modern soil also retains more nutrients compared to the thin layer of dirt that covered the ancient Earth. But the dynamics revealed in the study shed light on other newer threats to life in Earth’s oceans. The study’s authors note that others have made the argument that pollution from fertilizers, manure and other organic wastes, such as sewage, have placed the Earth’s oceans on the “edge of anoxia,” or a complete lack of oxygen.
“These new insights into the catastrophic results of natural events in the ancient world may serve as a warning about the consequences of similar conditions arising from human activity today,” Fillipelli said.
Molecular basis of the key regulator WRINKLED1 in plant oil biosynthesis
by Zhu Qiao, Que Kong, Wan Ting Tee, Audrey R. Q. Lim, Miao Xuan Teo, Vincent Olieric, Pui Man Low, Yuzhou Yang, Guoliang Qian, Wei Ma, Yong-Gui Gao in Science Advances
Scientists from Nanyang Technological University, Singapore (NTU Singapore) have successfully genetically modified a plant protein that is responsible for oil accumulation in plant seeds and edible nuts.
Demonstrating their patent-pending method, the model plant Arabidopsis accumulated 15 to 18 per cent more oil in its seeds when it was grown with the modified protein under laboratory conditions. Finding ways to make crops yield more oil in their seeds is a holy grail for the farming industry. However, most oil-producing crops — such as oil palm, soybean, sunflower, rapeseed, peanut — already have a high percentage of oil in their fruit or seed, and it is hard to increase their oil content through traditional crop crossbreeding methods.
Vegetable oils are commonly used in food processing, biofuels, soaps and perfumes, and the global market for them is estimated to be worth US$241.4 billion in 2021 and is expected to increase to US$ 324.1 billion by 2027[1]. Increasing the yield of oil from plants could also help the world in its quest for sustainability, helping to reduce the amount of arable land needed for oil-yielding crops. The secret to helping plants store more oil in their seeds is one of their proteins called WRINKLED1 (WRI1). Scientists have known for over two decades that WRI1 plays an important role in controlling plant seed oil production.
Now for the first time, a high-resolution structure of WRI1 has been imaged and reported by the NTU team, jointly led by Associate Professor Gao Yonggui and Assistant Professor Ma Wei from the School of Biological Sciences. The team detailed the molecular structure of WRI1 and how it binds to plant DNA — which signals to the plant how much oil to accumulate in its seeds.
Based on the understanding that the atomic structure of the WRI1-DNA complex revealed, the team modified WRI1 to enhance its affinity for DNA in a bid to improve oil yield. In this approach, some portions in WRI1 were selected for modifications to improve its binding to DNA and several forms of WRI1 were produced. These candidate WRI1s were then further tested to assess their ability to activate oil production in plant cells. As expected by the team, they showed that their modified versions of WRI1 increased DNA binding ten-fold compared to the original WRI1 — ultimately leading to more oil content in its seeds.
Assoc Prof Gao, a structural biologist said: “Being able to see exactly what WRI1 looks like and how it binds to DNA that is responsible for oil production in the plant was the key to understanding the entire process. WRI1 is an essential regulator that informs the plant how much oil to store in its seeds. Once we were able to visualise the ‘lock’, we then engineered the ‘key’ that can unlock the potential of WRI1.”
Analysing at the atomic level, the crystal structure of the WRI1 protein and the double helix DNA strands to which it binds, the team noticed this DNA binding domain was extensively conserved. This means that there were little to no variations, suggesting it could be a common binding mechanism for many plant species. Using this crystal structure of WRI1 as the ‘target’, the team then looked to modify WRI1, to enhance the binding affinity of the protein for its target DNA. The instructions for coding this modified WRI1 protein are then introduced into the target plant cells, after which the plant will use this new ‘set of instructions’ whenever it produces WRI1.
In lab experiments to observe how the modified WRI1 affects oil accumulation, both the modified protein and the unmodified form were injected into Nicotiana benthamiana leaves, and an analysis of triacylglycerol (a major form of dietary lipid in fats and oils) levels was carried out. The modified WRI1 protein generated more significant spikes in triacylglycerol production compared to the control plant introduced with the WRI1 unmodified form.
Subsequent experiments showed that the oil content in the seeds of the modified Arabidopsis thaliana contained more oil than the unmodified form. The offspring of this genetically modified plant will also bear the same modified WRI1 protein and produce more oil in their seeds. Asst Prof Ma, a plant molecular biologist who has been studying WRI1 since his postdoctoral training, said modifying WRI1 to improve its binding to DNA was a logical move for the team.
“We know that WRI1 is a protein that binds to a plant’s DNA sequence and sets off a specific chain of instructions that regulates the accumulation of oils in the seeds. The stronger the binding — the more oil the plant will concentrate in its seeds. Therefore, we chose to improve this portion of WRI1 that binds to its target DNA, which is highly conserved across many seed-bearing plants. Being highly conserved means many species of plants will have the exact same mechanism that can be modified, so we should be able to translate our oil-yielding modification easily to many different types of crops in future.” Asst Prof Ma explained.
“Plant seed oil is vital for the human diet and is used in many important industrial applications. Global demand for plant oil is increasing very quickly and our research contributes to efforts to improve seed oil production in a sustainable manner, and potentially reducing the environmental impact of agriculture.” Asst Prof Ma added.
Thirty percent conversion efficiency from radiofrequency power to thrust energy in a magnetic nozzle plasma thruster
by Kazunori Takahashi in Scientific Reports
A Tohoku University researcher has increased the performance of a high-power electrodeless plasma thruster, moving us one step closer to deeper explorations into space.
Innovations in terrestrial transportation technologies, such as cars, trains, and aircraft, have driven historical technologies and industries so far; now, a similar breakthrough is occurring in space thanks to electric propulsion technology. Electric propulsion is a technique utilizing electromagnetic fields to accelerate a propellant and to generate thrust that propels a spacecraft. Space agencies have pioneered electric propulsion technology as the future of space exploration.
Already, several space missions have successfully been completed using electric propulsion devices, such as gridded ion thrusters and Hall thrusters. Solar power is converted into thrust energy when the propellant becomes ionized, i.e., a plasma, and gets accelerated by electromagnetic fields. Yet, the electrodes necessary for these devices limit their lifetime, since they get exposed to and damaged by the plasma, especially at a high-power level.
To circumvent this, scientists have turned to electrodeless plasma thrusters. One such technology harnesses radio frequency (rf) to generate plasma. An antenna emits radio waves into a cylindrical chamber to create plasma, where a magnetic nozzle channels and accelerates the plasma to generate thrust. MN rf plasma thrusters, or helicon thrusters as they are sometimes known, offer simplicity, operational flexibility, and a potentially high thrust-to-power ratio. But the development of MN rf plasma thrusters has been stymied by the conversion efficiency of the rf power to thrust energy. Early experiments generated single digit conversion rates, but more recent studies have reached a modest outcome of 20%.
In a recent study, Professor Kazunori Takahashi, from Tohoku University’s Department of Electrical Engineering, has achieved a 30% conversion efficiency. Whilst mature electric propulsion devices often use xenon gas, which is expensive and difficult to supply in sufficient quantities, the current 30% efficiency was obtained with argon propellant. This indicates that a MN rf plasma thruster would reduce the cost and the resource load from the Earth.
“Applying a cusp-type magnetic field inhibited the energy loss that generally occurs to the plasma source wall,” Takahashi said. “The breakthrough opens the door to advances in high-power space transportation technology.”
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