GT/ Unused renewable energy an option for powering NFT trade
Energy & green technology biweekly vol.53, 13th July — 27th July
TL;DR
- Unused solar, wind, and hydroelectric power in the U.S. could support the exponential growth of transactions involving non-fungible tokens (NFTs), researchers have found.
- Organic electronics can make a decisive contribution to decarbonization and, at the same time, help to cut the consumption of rare and valuable raw materials. To do so, it is not only necessary to further develop manufacturing processes, but also to devise technical solutions for recycling as early on as the laboratory phase. Materials scientists are now promoting this circular strategy.
- Experiments at a unique wind tunnel show that laws formulated more than 80 years ago and their extensions only incompletely explain turbulent flows.
- Sulphuric acid is the world’s most used chemical. It is an important reagent used in many industries and it is used in the manufacture of everything from paper, pharmaceuticals and cosmetics to batteries, detergents and fertilizers. It is therefore a worldwide challenge that sulphuric acid often contains one of the most toxic substances — mercury. Researchers have now developed a method that can reduce the levels of mercury in sulphuric acid by more than 90 per cent — even from low levels.
- Engineers have developed a cost-effective and environmentally friendly way to remove heavy metals, including copper and zinc, from biosolids. The team’s work advances other methods for heavy-metal removal by recycling the acidic liquid waste that is produced during the recovery phase, instead of throwing it away.
- To overcome global energy challenges and fight the looming environmental crisis, researchers around the world investigate new materials for converting sunlight into electricity. Some of the most promising candidates for high-efficiency low-cost solar cell applications are based on lead halide perovskite (LHP) semiconductors. Despite record-breaking solar cell prototypes, the microscopic origin of the surprisingly excellent optoelectronic performance of this material class is still not completely understood. Now, an international team of physicists and chemists has demonstrated laser-driven control of fundamental motions of the LHP atomic lattice.
- A team of engineers has recently shown that nearly any material can be turned into a device that continuously harvests electricity from humidity in the air. Researchers describe the ‘generic Air-gen effect’ — nearly any material can be engineered with nanopores to harvest, cost effective, scalable, interruption-free electricity. The secret lies in being able to pepper the material with nanopores less than 100 nanometers in diameter.
- Scientists took a deep dive into the economic and environmental value of community recycling efforts and compared it to the value of other climate change mitigation practices, concluding it provides a return on investment.
- Researchers have demonstrated how carbon dioxide can be captured from industrial processes — or even directly from the air — and transformed into clean, sustainable fuels using just the energy from the Sun.
- New carbon capture technology can generate a continuous, high-purity carbon dioxide stream from diluted, or low-concentration, gas streams using only electricity and a water-and-oxygen-based reaction.
- 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
Climate concerns and the future of nonfungible tokens: Leveraging environmental benefits of the Ethereum Merge
by Apoorv Lal, Fengqi You in Proceedings of the National Academy of Sciences
Unused solar, wind, and hydroelectric power in the U.S. could support the exponential growth of transactions involving non-fungible tokens (NFTs), Cornell Engineering researchers have found.
Fengqi You is corresponding author of the paper. You’s co-author is Apoorv Lal, graduate student in chemical and biomolecular engineering and a member of the You Research Group.
Processing of NFT transactions, which has increased fourfold over the past five years, was once highly energy-intensive but has been made more sustainable with a recent switch to a more energy-efficient algorithm. But those savings, the researchers said, will be largely offset by the anticipated boom in yearly NFT activity. Excess renewable energy, due to lack of storage capability, forces grid operators to curtail production. You’s idea would put that unused energy-production potential to good use.
“It’s the same idea as a car sitting in someone’s garage,” You said. “If it’s not being driven, they could lend it to someone for carsharing. In our case, wind, solar and hydro power sources that aren’t being utilized could be used to do something good.”
“Of course, this would be up to the industry and policymakers,” he said, “but technology-wise, we show it’s very feasible because these power sources are there already.”
The increased NFT processing activity could be powered, in part, from un- or underutilized existing power sources. Fifty megawatts of potential hydropower from existing U.S. dams that are not currently used to generate power, or a 15% utilization of wind and solar energy that can’t currently be used or stored from sources in Texas, could be used to power an exponential increase in NFT transactions.
Blockchain technologies, including NFT transactions, offer a high level of security in a variety of applications, but the energy required to process each transaction is problematic in a warming world.
“In the beginning, people only cared about the usefulness of these applications,” Lal said. “But then they started to realize the energy and climate impacts, because the crux of all these applications is the utilization of massive amounts of energy.”
Without any efforts to make NFT transaction processing more sustainable, the authors wrote, their annual emissions will reach an equivalent of 0.37 megatons of carbon dioxide — close to the CO2 emissions from 1 million single-trip flights for a passenger from New York to London.
In September of 2022, the Ethereum blockchain responded to the call for more sustainable trading by switching from an energy-intensive proof of work (PoW) algorithm to a proof of stake (PoS) consensus mechanism, which requires less computing power. Energy consumption decreased drastically following the switch, known as the Ethereum Merge. Still, the authors wrote, an exponential rise in recorded NFT transactions would translate to more validators operating on the network. Toward the end of this decade, energy consumed by an exponential increase in NFT transactions could be equivalent to that of 100,000 U.S. households. So even with significantly less energy consumption for individual NFT transactions, the cumulative effect of increased numbers of validators operating on fossil fuel-dominant grids will lead to a further rise in the associated carbon debt.
“By the end of this decade,” You said, “the carbon produced by NFT transactions may be roughly equivalent to that produced in one year by a 600-megawatt coal-fired power plant.”
The authors evaluated two hydroelectric energy carriers — green hydrogen and green ammonia (more energy-dense than hydrogen) — for their viability, noting that their cost savings are influenced by multiple factors, including transportation distances and the utilization levels of available renewable energy sources. Retrofitting these existing power sources could be challenging, the authors said, but would still be good for energy carriers and the planet.
“NFT processing is very power-hungry,” You said, “so this turns out to be a good way to take advantage of these curtailments.”
Sustainability considerations for organic electronic products
by Iain McCulloch, Michael Chabinyc, Christoph Brabec, Christian Bech Nielsen, Scott Edward Watkins in Nature Materials
Organic electronics can make a decisive contribution to decarbonization and, at the same time, help to cut the consumption of rare and valuable raw materials. To do so, it is not only necessary to further develop manufacturing processes, but also to devise technical solutions for recycling as early on as the laboratory phase. Materials scientists from Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) are now promoting this circular strategy in conjunction with researchers from the UK and USA in the
Organic electronic components, such as solar modules, have several exceptional features. They can be applied in extremely thin layers on flexible carrier materials and therefore have a wider range of applications than crystalline materials. Since their photoactive substances are carbon based, they also contribute to cutting the consumption of rare, expensive and sometimes toxic materials such as iridium, platinum and silver.
Organic electronic components are experiencing major growth in the field of OLED technologies in particular, and above all for television or computer screens. “One the one hand, this is progress, but on the other, it causes some problems,” says Prof. Dr. Christoph Brabec, Chair of Materials Science (Materials in Electronics and Energy Technology) at FAU and Director of the Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (HI ERN). As a materials scientist, Brabec sees the danger of permanently incorporating environmentally friendly technology into a device architecture that is not sustainable on the whole. This not only affects electronic devices, but also organic sensors in textiles that have an extremely short operating life.
Brabec: “Applied research in particular must now set the course to ensure that electronic components and all their individual parts must leave an ecological footprint that is as small as possible during their entire lifecycle.”
The further development of organic electronics themselves is elementary here, since new materials and more efficient manufacturing processes lead to the reduction of outlay and energy during production. “Compared with simple polymers, the manufacturing process for the photoactive layer requires significantly higher amounts of energy as it is deposited in a vacuum at high temperatures,” explains Brabec. The researchers are therefore proposing cheaper and more environmentally-friendly processes, such as deposition from water-based solutions and printing using inkjet processes. Brabec: “One major challenge is developing functional materials that can be processed without toxic solvents that are harmful to the environment.” In the case of OLED screens, inkjet printing also offers the possibility of replacing precious metals such as iridium and platinum with organic materials.
In addition to their efficiency, the operating stability of materials is decisive. Complex encapsulation is required in order to protect the vacuum-deposited carbon layers of organic solar modules, which can make up to two thirds of their overall weight. More robust combinations of materials could contribute to significant savings in materials, weight and energy.
To make a realistic evaluation of the environmental footprint of organic electronics, the entire product lifecycle has to be considered. In terms of output, organic photovoltaic systems are still lagging behind conventional silicon modules, but 30% less CO2 is emitted during the manufacturing process. Aiming for maximum efficiency levels is not everything, says
Brabec: “18 percent could make more sense environmentally than 20, if it’s possible to manufacture the photoactive material in five steps instead of eight.”
In addition, the shorter operating life of organic modules is also relative if you look more closely. Although photovoltaic modules based on silicon last longer, they are very difficult to recycle. “Biocompatibility and biodegradability will increasingly become important criteria, both for product development as well as for packaging design,” says Christoph Brabec. “We really must start taking recycling into consideration in the laboratory.” This means, for example, using substrates that can either be easily recycled or that are as biodegradable as the active substances. Using what is known as multilayer designs as early on as the product design phase could ensure that various materials can easily be separated and recycled at the end of the product lifecycle.
Brabec: “This cradle-to-cradle approach will be a decisive prerequisite for establishing organic electronics as an important component in the transition to renewable energy.”
Universal Velocity Statistics in Decaying Turbulence
by Christian Küchler, Gregory P. Bewley, Eberhard Bodenschatz in Physical Review Letters
Experiments at the unique wind tunnel of the Max Planck Institute for Dynamics and Self-Organization (MPI-DS) in Göttingen show that laws formulated more than 80 years ago and their extensions only incompletely explain turbulent flows.
Stirring a cup of coffee creates a turbulent flow with large and very small vortices. The vortices of different sizes influence each other by transferring energy from a larger vortex to a smaller one, down to the smallest vortex, which dissipates in the liquid due to friction. This concept was first described by mathematician Andrei Kolmogorov, who established general scaling laws for turbulent flows in 1941. Using these and further refinements, computer simulations for engineered flows, weather forecasts and climate models are still created from empirical data today.
“We found that these scaling laws seem to apply only to strongly idealized flows,” reports Christian Küchler, first author of the study. Previously, it had been assumed that they were universally valid. Even before that, measurements in wind tunnels at lower turbulence levels could not confirm the theoretical predictions, but they were usually attributed to the turbulence strength being too low. “In our unique channel, we can use gases at high pressures and thus achieve extremely high degrees of turbulence,” says MPI-DS director Eberhard Bodenschatz, who designed the channel for his research.
By selectively generating turbulence and using an active grid, developed at MPI-DS by coauthor Greg Bewley from Cornell University, the researchers were able to show that systematic deviations from Kolmogorov’s predictions occur even in the strongest turbulence. This implies that medium-sized eddies in real flows are not completely decoupled from the very large eddies in a system by energy transfer, as has been suspected since 1941. Moreover, these new results are universal and do not depend on the strength of turbulence in the channel.
“Our wind tunnel allows measurements that would otherwise not be possible,” says Eberhard Bodenschatz, director at MPI-DS, explaining the special feature of the research facility. “We can better understand how turbulent flows really behave and develop new models on this basis,” he continues. For instance, these experiments can contribute to a better understanding of turbulence in engineered flows or the atmosphere. There, the effect of turbulence is one of the largest uncertainty factors in modern climate models and weather forecasting.
Mercury Removal from Concentrated Sulfuric Acid by Electrochemical Alloy Formation on Platinum
by Vera Roth, Julia Järlebark, Alexander Ahrnens, Jens Nyberg, Justin Salminen, Teodora Retegan Vollmer, Björn Wickman in ACS ES&T Engineering
Sulphuric acid is the world’s most used chemical. It is an important reagent used in many industries and it is used in the manufacture of everything from paper, pharmaceuticals and cosmetics to batteries, detergents and fertilisers. It is therefore a worldwide challenge that sulphuric acid often contains one of the most toxic substances — mercury. Researchers at Chalmers University of Technology, Sweden, have now developed a method that can reduce the levels of mercury in sulphuric acid by more than 90 per cent — even from low levels.
“Until now, there has been no viable method for purifying finished sulphuric acid at all. With such a radical reduction in the mercury content, we come well below the current limit values. Such pure high quality sulphuric acid is in high demand in industrial applications and an important step in reducing environmental impact,” says research leader Björn Wickman, Associate Professor at the Department of Physics at Chalmers.
Sulphuric acid is produced either from sulphur from the petroleum industry or as a by-product in the mining industry’s smelters. In the latter case, mercury, which is naturally present in the ore, can end up in the finished products. Also recycled streams in the smelters can contain mercury. Mercury dispersal is a worldwide problem, as the substance is volatile and can be dispersed by air over large areas. This toxic heavy metal is then washed into streams and lakes when it rains. It is stored in the soil, water and living organisms, impacting the entire food chain. It can damage the brains and central nervous systems of humans and animals.
According to a report from the United Nations Environment Programme (UNEP), emissions of mercury to the atmosphere increased by an estimated 20 per cent from 2010 to 2015. In 2015, about 2,200 tonnes of mercury were emitted into the air as a result of human activities such as cement manufacture, small-scale gold mining, coal burning, metal production and other manufacturing industries. In addition, an estimated 1,800 tonnes of mercury ended up in the soil and water in that same year. According to the report, mercury concentrations in the atmosphere may have increased by 450 per cent in the last century.
“Any and all ways we can reduce mercury emissions are good, because any mercury that is emitted accumulates in the environment and continues to pose a health threat for thousands of years,” says Wickman.
Five years ago, his research team at Chalmers presented a pioneering method for removing mercury from water using electrochemical processes. The method is based on a metal electrode taking up the toxic metal and forming an alloy. The mercury can then be safely removed, and the electrode reused. Now the researchers have taken this technology one step further, and in a new study they have shown how mercury can be removed from concentrated sulphuric acid.
The experiments with sulphuric acid were done in collaboration with mining and metals refining company Boliden and the company Atium, a spin-off from the Chalmers School of Entrepreneurship with the aim of bringing the removal of mercury from water and chemicals to market. The researchers now hope to be able to move forward with their partners and develop a type of reactor through which sulphuric acid can flow and be purified at the same time.
Today, mercury is mostly removed at an earlier stage — from the concentrates and recycled streams at the smelter before sulphuric acid is produced. This is an established process, but leaves trace amounts of mercury into final products.
“Purifying the sulphuric acid as well prevents additional mercury emissions, while allowing industry to operate more cost-effectively and produce a high-purity, non-toxic product. The next step will be to scale up the method into a pilot process that is closer to real-world volumes of thousands of tonnes,” says Vera Roth, doctoral student at Chalmers and first author of the recently published article.
Investigations into the closed-loop hydrometallurgical process for heavy metals removal and recovery from biosolids via mild acid pre-treatment
by Ibrahim Gbolahan Hakeem, Pobitra Halder, Shefali Aktar, Mojtaba Hedayati Marzbali, Abhishek Sharma, Aravind Surapaneni, Graeme Short, Jorge Paz-Ferreiro, Kalpit Shah in Hydrometallurgy
Engineers in Melbourne have developed a cost-effective and environmentally friendly way to remove heavy metals, including copper and zinc, from biosolids.
The team’s work, led by RMIT University in collaboration with South East Water and Manipal University in India, advances other methods for heavy-metal removal by recycling the acidic liquid waste that is produced during the recovery phase, instead of throwing it away. Lead senior researcher Professor Kalpit Shah from RMIT said the heavy metals found in biosolids — treated sewage sludge — can be valuable, and the recovery of metals such as copper and zinc can be achieved using the team’s approach.
“Our innovation helps ensure the resulting biosolids do not leach heavy metals into the environment and retain the nutrients that can be used for land applications,” said Shah, Deputy Director (Academic) of the ARC-funded Training Centre for the Transformation of Australia’s Biosolids Resources in RMIT’s School of Engineering.
“With further processing, the biosolids can be turned into high-grade biochar, which is a renewable energy resource and has a range of applications including as a fertiliser.”
The overall metal-removal process occurs over three stages: extraction, purification and recovery. Prior to the team’s work, metal recovery from biosolids had not been fully explored among researchers beyond the first stage. The first author of the journal article, RMIT PhD researcher Ibrahim Hakeem, said biosolids can contain several metals locked within organic matter, making purification and metal recovery challenging.
“We devised an approach where we were able to recover the metals one by one and did so with a closed-loop solution that causes least harm to the environment,” said Hakeem, from RMIT’s School of Engineering.
The challenge is that reducing the organic matter through pyrolysis results in a higher concentration of heavy metals in the biochar, which the team’s new technique helps resolve. The application of biosolids to agricultural land in Australia is subject to guidelines and regulations that specify limits for heavy-metal concentrations, ensuring that biosolids can be safely used as fertiliser. The team aims to work with water authorities to use its heavy-metal removal technique prior to pyrolysis.
“The transition to a circular economy is important for the water industry,” said South East Water’s R&D Manager, Dr David Bergmann. “We have previously seen our sludge as waste, but now through research like this we are able to see that it’s possible to clean it up and convert it into potential materials with value and further applications.”
Nonlinear terahertz control of the lead halide perovskite lattice
by Maximilian Frenzel, Marie Cherasse, Joanna M. Urban, Feifan Wang, Bo Xiang, Leona Nest, Lucas Huber, Luca Perfetti, Martin Wolf, Tobias Kampfrath, X.-Y. Zhu, Sebastian F. Maehrlein in Science Advances
To overcome global energy challenges and fight the looming environmental crisis, researchers around the world investigate new materials for converting sunlight into electricity. Some of the most promising candidates for high-efficiency low-cost solar cell applications are based on lead halide perovskite (LHP) semiconductors. Despite record-breaking solar cell prototypes, the microscopic origin of the surprisingly excellent optoelectronic performance of this material class is still not completely understood.
Now, an international team of physicists and chemists from Fritz Haber Institute of the Max Planck Society, École Polytechnique in Paris, Columbia University in New York, and the Free University in Berlin demonstrated laser-driven control of fundamental motions of the LHP atomic lattice. By applying a sudden electric field spike faster than a trillionth of a second (picosecond) in the form of a single light cycle of far-infrared Terahertz radiation, the investigators unveiled the ultrafast lattice response, which might contribute to a dynamic protection mechanism for electric charges. This precise control over the atomic twist motions will allow to create novel non-equilibrium material properties, potentially providing hints for designing the solar cell material of the future.
The investigated hybrid LHP solar cell materials consist of an inorganic crystal lattice, which acts as periodic cages for hosting organic molecules. The interplay of free electronic charges with this hybrid lattice and its impurities determines how much electricity can be extracted from the sun light’s energy. Understanding this complicated interaction might be the key for a microscopic understanding of the outstanding optoelectronic performance of LHPs. Researchers from Fritz Haber Institute in Berlin and their international colleagues have now been able to isolate the lattice response to an electric field on timescales faster than 100 femtoseconds, that is one tenth of a trillionth of a second. The electric field has been applied by an intense laser pulse containing only a single cycle of far-infrared, so-called Terahertz (THz), light.
“This THz field is so strong and so fast that it may mimic the local electric field of an excited charge carrier immediately after the absorption of a quantum of sunlight,” explains Maximilian Frenzel, one of the main authors performing the experiments.
By this approach, the investigators observe a concerted motion of the crystal lattice, mainly consisting of back and forth tilting of the octahedral building blocks of the inorganic cage. These nonlinearly excited vibrations can lead to — so far neglected — higher order screening effects, contributing to an often discussed charge carrier protection mechanism.
“Moreover, the related tilting angle plays a dominating role in determining the fundamental material properties, such as the crystallographic phase or electronic bandgap,” clarifies Dr. Sebastian Maehrlein, leader of the international research project.
Thus, instead of static chemical tuning of material properties, ultrafast dynamic material design comes into reach: “As we can now modulate these twist angles by a single THz light cycle,” summarizes Dr. Maehrlein, “in future we might be able to control material properties on demand or even discover novel exotic states of this emerging material class.” By assessing such dynamic states of matter, the researchers hope to contribute some hints for designing the energy materials of the future.
Generic Air‐Gen Effect in Nanoporous Materials for Sustainable Energy Harvesting from Air Humidity
by Xiaomeng Liu, Hongyan Gao, Lu Sun, Jun Yao in Advanced Materials
A team of engineers at the University of Massachusetts Amherst has recently shown that nearly any material can be turned into a device that continuously harvests electricity from humidity in the air. The secret lies in being able to pepper the material with nanopores less than 100 nanometers in diameter.
“This is very exciting,” says Xiaomeng Liu, a graduate student in electrical and computer engineering in UMass Amherst’s College of Engineering and the paper’s lead author. “We are opening up a wide door for harvesting clean electricity from thin air.”
“The air contains an enormous amount of electricity,” says Jun Yao, assistant professor of electrical and computer engineering in the College of Engineering at UMass Amherst, and the paper’s senior author. “Think of a cloud, which is nothing more than a mass of water droplets. Each of those droplets contains a charge, and when conditions are right, the cloud can produce a lightning bolt — but we don’t know how to reliably capture electricity from lightning. What we’ve done is to create a human-built, small-scale cloud that produces electricity for us predictably and continuously so that we can harvest it.”
The heart of the human-made cloud depends on what Yao and his colleagues call the “generic Air-gen effect,” and it builds on work that Yao and co-author Derek Lovley, Distinguished Professor of Microbiology at UMass Amherst, had previously completed in 2020 showing that electricity could be continuously harvested from the air using a specialized material made of protein nanowires grown from the bacterium Geobacter sulfurreducens.
“What we realized after making the Geobacter discovery,” says Yao, “is that the ability to generate electricity from the air — what we then called the ‘Air-gen effect’ — turns out to be generic: literally any kind of material can harvest electricity from air, as long as it has a certain property.”
That property? “It needs to have holes smaller than 100 nanometers (nm), or less than a thousandth of the width of a human hair.” This is because of a parameter known as the “mean free path,” the distance a single molecule of a substance, in this case water in the air, travels before it bumps into another single molecule of the same substance. When water molecules are suspended in the air, their mean free path is about 100 nm.
Yao and his colleagues realized that they could design an electricity harvester based around this number. This harvester would be made from a thin layer of material filled with nanopores smaller than 100 nm that would let water molecules pass from the upper to the lower part of the material. But because each pore is so small, the water molecules would easily bump into the pore’s edge as they pass through the thin layer. This means that the upper part of the layer would be bombarded with many more charge-carrying water molecules than the lower part, creating a charge imbalance, like that in a cloud, as the upper part increased its charge relative to the lower part. This would effectually create a battery — one that runs as long as there is any humidity in the air.
“The idea is simple,” says Yao, “but it’s never been discovered before, and it opens all kinds of possibilities.” The harvester could be designed from literally all kinds of material, offering broad choices for cost-effective and environment-adaptable fabrications. “You could image harvesters made of one kind of material for rainforest environments, and another for more arid regions.”
And since humidity is ever-present, the harvester would run 24/7, rain or shine, at night and whether or not the wind blows, which solves one of the major problems of technologies like wind or solar, which only work under certain conditions.
Finally, because air humidity diffuses in three-dimensional space and the thickness of the Air-gen device is only a fraction of the width of a human hair, many thousands of them can be stacked on top of each other, efficiently scaling up the amount of energy without increasing the footprint of the device. Such an Air-gen device would be capable of delivering kilowatt-level power for general electrical utility usage.
“Imagine a future world in which clean electricity is available anywhere you go,” says Yao. “The generic Air-gen effect means that this future world can become a reality.”
The hidden economic and environmental costs of eliminating kerb-side recycling
by Malak Anshassi, Timothy G. Townsend in Nature Sustainability
Curbside recycling can compensate for the greenhouse gas emissions from garbage destined for landfills, says a new study that encourages towns and cities to continue offering recycling services to meet their climate goals.
The study’s authors took a deep dive into the economic and environmental value of community recycling efforts and compared it to the value of other climate change mitigation practices. They concluded that recycling provides a return on investment similar to or better than environmentally friendly strategies like transitioning to electric vehicles or purchasing green power, which is electricity from clean, renewable energy sources.
“Eliminating recycling squanders one of the easiest opportunities for communities and citizens to help lessen the impact of climate change and reduce our demands on natural resources,” said Timothy Townsend, a professor of environmental engineering sciences at the University of Florida and one of the study’s authors. “Recycling won’t solve the problem alone, but it is part of the puzzle.”
Towns and cities across the country have canceled or scaled back recycling programs due to rising costs. Recent restrictions on recyclable material collected by major international markets have contributed to the cost increase, according to the study. Townsend and Malak Anshassi, of Florida Polytechnic University, set out to assess how much more expensive recycling is compared to garbage collection only and to see if the resale value of recyclables was at any time sufficient enough for the program to pay for itself. They also analyzed the role residential recycling plays in reducing greenhouse gas emissions and conserving natural resources.
When recycling markets were most lucrative in 2011, U.S. recycling costs were as little as $3 a year per household. Beginning in 2018 and through 2020, tighter restrictions went into place and the COVID-19 pandemic disrupted the markets, and the cost for recycling ranged from $34 to $42. The study asserts that even with higher costs, the investment offsets the greenhouse gas emissions from non-recycled waste buried in landfills.
Townsend and Anshassi say that if local governments restructure their recycling programs to target materials with the greatest market value and the highest potential for carbon offset, recycling can pay for itself and reduce greenhouse gas emissions. They identify higher-value materials as newspaper, cardboard, aluminum and steel cans, and HDPE and PET plastic bottles.
“Recycling is a public service provided by local governments to their residents, just like providing water, sewer, roads,” Townsend says. “It is a service that does have an expense, but it always has. I would argue that it does not cost much when you compare it to other services we pay for, and when markets are good, you hardly pay anything.”
Researchers also suggest that local and state governments could implement policies to help relieve the cost burden of recycling, like establishing a minimum amount of recyclable materials that manufacturers must use in packaging or products and placing some of the responsibility for recycling costs on the manufacturers.
“If we learn collectively to recycle better, we can reduce the costs to pretty much break even,” Townsend says. “From an environmental perspective, that’s a good return on your investment.”
Integrated capture and solar-driven utilization of CO2 from flue gas and air
by Sayan Kar, Motiar Rahaman, Virgil Andrei, Subhajit Bhattacharjee, Souvik Roy, Erwin Reisner in Joule
Researchers have demonstrated how carbon dioxide can be captured from industrial processes — or even directly from the air — and transformed into clean, sustainable fuels using just the energy from the Sun.
The researchers, from the University of Cambridge, developed a solar-powered reactor that converts captured CO2 and plastic waste into sustainable fuels and other valuable chemical products. In tests, CO2 was converted into syngas, a key building block for sustainable liquid fuels, and plastic bottles were converted into glycolic acid, which is widely used in the cosmetics industry.
Unlike earlier tests of their solar fuels technology however, the team took CO2 from real-world sources — such as industrial exhaust or the air itself. The researchers were able to capture and concentrate the CO2 and convert it into sustainable fuel. Although improvements are needed before this technology can be used at an industrial scale, the results represent another important step toward the production of clean fuels to power the economy, without the need for environmentally destructive oil and gas extraction.
For several years, Professor Erwin Reisner’s research group, based in the Yusuf Hamied Department of Chemistry, has been developing sustainable, net-zero carbon fuels inspired by photosynthesis — the process by which plants convert sunlight into food — using artificial leaves. These artificial leaves convert CO2 and water into fuels using just the power of the sun. To date, their solar-driven experiments have used pure, concentrated CO2 from a cylinder, but for the technology to be of practical use, it needs to be able to actively capture CO2 from industrial processes, or directly from the air. However, since CO2 is just one of many types of molecules in the air we breathe, making this technology selective enough to convert highly diluted CO2 is a huge technical challenge.
“We’re not just interested in decarbonisation, but de-fossilisation — we need to completely eliminate fossil fuels in order to create a truly circular economy,” said Reisner. “In the medium term, this technology could help reduce carbon emissions by capturing them from industry and turning them into something useful, but ultimately, we need to cut fossil fuels out of the equation entirely and capture CO2 from the air.”
The researchers took their inspiration from carbon capture and storage (CCS), where CO2 is captured and then pumped and stored underground.
“CCS is a technology that’s popular with the fossil fuel industry as a way to reduce carbon emissions while continuing oil and gas exploration,” said Reisner. “But if instead of carbon capture and storage, we had carbon capture and utilisation, we could make something useful from CO2 instead of burying it underground, with unknown long-term consequences, and eliminate the use of fossil fuels.”
The researchers adapted their solar-driven technology so that it works with flue gas or directly from the air, converting CO2 and plastics into fuel and chemicals using only the power of the sun. By bubbling air through the system containing an alkaline solution, the CO2 selectively gets trapped, and the other gases present in air, such as nitrogen and oxygen, harmlessly bubble out. This bubbling process allows the researchers to concentrate the CO2 from air in solution, making it easier to work with.
The integrated system contains a photocathode and an anode. The system has two compartments: on one side is captured CO2 solution that gets converted into syngas, a simple fuel. On the other plastics are converted into useful chemicals using only sunlight.
“The plastic component is an important trick to this system,” said co-first author Dr Motiar Rahaman. “Capturing and using CO2 from the air makes the chemistry more difficult. But, if we add plastic waste to the system, the plastic donates electrons to the CO2. The plastic breaks down to glycolic acid, which is widely used in the cosmetics industry, and the CO2 is converted into syngas, which is a simple fuel.”
Continuous carbon capture in an electrochemical solid-electrolyte reactor
by Peng Zhu, Zhen-Yu Wu, Ahmad Elgazzar, Changxin Dong, Tae-Ung Wi, Feng-Yang Chen, Yang Xia, Yuge Feng, Mohsen Shakouri, Jung Yoon Kim, Zhiwei Fang, T. Alan Hatton, Haotian Wang in Nature
New technology developed by Rice University engineers could lower the cost of capturing carbon dioxide from all types of emissions, a potential game-changer for both industries looking to adapt to evolving greenhouse gas standards and for the emergent energy-transition economy.
According to a study, the system from the lab of chemical and biomolecular engineer Haotian Wang can directly remove carbon dioxide from sources ranging from flue gas to the atmosphere by using electricity to induce a water-and-oxygen-based electrochemical reaction. This technological feat could turn direct air capture from fringe industry ⎯ there are only 18 plants currently in operation worldwide ⎯ into a promising front for climate change mitigation. Most carbon-capture systems involve a two-step process: First, high-pH liquids are used to separate the carbon dioxide, which is acidic, from mixed-gas streams such as flue gas. Next, the carbon dioxide is regenerated from the solution through heating or by injecting a low-pH liquid.
“Once the carbon dioxide is trapped in these solvents, you have to regenerate it,” Wang said. “Traditional amine scrubbing methods require temperatures of 100–200 degrees Celsius (212–392 Fahrenheit). For calcium carbonate-based processes you need temperatures as high as 900 Celsius (1652 Fahrenheit).
“There are literally no chemicals produced or consumed with our process. We also don’t need to heat up or pressurize our device, we just need to plug it into a power outlet and it will work.”
Another drawback of current carbon-capture technologies is their reliance on large-scale, centralized infrastructure. By contrast, the system developed in the Wang lab is a scalable, modular, point-of-use concept that can be adapted to a variety of scenarios.
“The technology can be scaled up to industrial settings ⎯ power plants, chemical plants ⎯ but the great thing about it is that it allows for small-scale use as well: I can even use it in my office,” Wang said. “We could, for example, pull carbon dioxide from the atmosphere and continuously inject that concentrated gas into a greenhouse to stimulate plant growth. We’ve heard from space technology companies interested in using the device on space stations to remove the carbon dioxide astronauts exhale.”
The reactor developed by Wang and his team can continuously remove carbon dioxide from a simulated flue gas with efficiency above 98% using a relatively low electricity input.
“The electricity used to power a 50-watt lightbulb for an hour will yield 10 to 25 liters of high-purity carbon dioxide,” said Peng Zhu, a chemical and biomolecular engineering graduate student and lead author on the study.
“This is great news considering that renewable electricity is becoming more and more cost-effective,” Wang said.
The reactor consists of a cathode set up to perform oxygen reduction, an oxygen evolution reaction-performing anode and a compact yet porous solid-electrolyte layer that allows efficient ion conduction. An earlier version of the reactor was used to reduce carbon dioxide into pure liquid fuels and reduce oxygen into pure hydrogen peroxide solutions.
“Previously, our group focused mainly on carbon dioxide utilization,” Zhu said. “We worked on producing pure liquid products like acetic acid, formic acid, etc.”
According to Wang, Zhu observed during the research process that gas bubbles flowed out of the reactor’s middle chamber along with the liquids.
“At the beginning, we didn’t pay a lot of attention to this phenomenon,” Wang said. “However, Peng observed that if we applied more current there were more bubbles. That’s a direct correlation, which means that something not random is happening.”
The researchers realized that the alkaline interface generated during reduction reactions at the reactor’s cathode side interacted with carbon dioxide molecules to form carbonate ions . The carbonate ions migrate into the reactor’s solid-electrolyte layer where they combine with protons resulting from water oxidation at the anode side, forming a continuous flow of high-purity carbon dioxide.
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