GT/ Groundbreaking green propane production method

Paradigm
Paradigm
Published in
31 min readAug 24, 2023

Energy & green technology biweekly vol.55, 11th August — 24th August

TL;DR

  • New research reveals a promising breakthrough in green energy: an electrolyzer device capable of converting carbon dioxide into propane in a manner that is both scalable and economically viable.
  • A new analysis reveals that soft technology, the processes to design and deploy a solar energy system, contributed far less to the total cost declines of solar installations than previously estimated. Their quantitative model shows that driving down solar energy costs in the future will likely require either improving soft technology or reducing system dependencies on soft technology features.
  • Researchers are making progress on the design of a solar battery made from an abundant, non-toxic and easily synthesized material composed of 2D carbon nitride.
  • A research team recently developed a stable artificial photocatalytic system that is more efficient than natural photosynthesis. The new system mimics a natural chloroplast to convert carbon dioxide in water into methane, a valuable fuel, very efficiently using light. This is a promising discovery, which could contribute to the goal of carbon neutrality.
  • Researchers have developed a multimodal platform to image biohybrids — microorganisms that use solar energy to convert carbon dioxide into value-added chemical products — to better understand how they function and how they can be optimized for more efficient energy conversion.
  • Proton exchange membrane water electrolyzers converts surplus electric energy into transportable hydrogen energy as a clean energy solution. However, slow oxygen evolution reaction rates and high loading levels of expensive metal oxide catalysts limit its practical feasibility. Now, researchers have developed a new tantalum oxide-supported iridium catalyst that significantly boosts the oxygen evolution reaction speed. Additionally, it shows high catalytic activity and long-term stability in prolonged single cell operation.
  • Scientists engineered microbes to make the ingredients for recyclable plastics — replacing finite, polluting petrochemicals with sustainable alternatives. The new approach shows that renewable, recyclable plastics are not only possible, but also outperform those from petrochemicals.
  • Polyester is the second most used textile in the world and an environmental menace, especially because most of it never gets recycled. The fabric, a blend of plastic and cotton, has been difficult for the industry to separate and therefore recycle. Now, a group of young chemists has invented a green and surprisingly simple solution using a single household ingredient.
  • The activity level of six bat species was significantly reduced at solar farm sites, researchers have observed.
  • Engineers have created a ‘supercapacitor’ made of ancient, abundant materials, that can store large amounts of energy. Made of just cement, water, and carbon black (which resembles powdered charcoal), the device could form the basis for inexpensive systems that store intermittently renewable energy, such as solar or wind energy.
  • 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

Imidazolium-functionalized Mo3P nanoparticles with an ionomer coating for electrocatalytic reduction of CO2 to propane

by Mohammadreza Esmaeilirad, Zhen Jiang, Ahmad M. Harzandi, Alireza Kondori, Mahmoud Tamadoni Saray, Carlo U. Segre, Reza Shahbazian-Yassar, Andrew M. Rappe, Mohammad Asadi in Nature Energy

A paper based on pioneering research done at Illinois Institute of Technology reveals a promising breakthrough in green energy: an electrolyzer device capable of converting carbon dioxide into propane in a manner that is both scalable and economically viable.

As the United States races toward its target of net-zero greenhouse gas emissions by 2050, innovative methods to reduce the significant carbon dioxide emissions from electric power and industrial sectors are critical. Mohammad Asadi, assistant professor of chemical engineering at Illinois Tech, spearheaded this groundbreaking research.

“Making renewable chemical manufacturing is really important,” says Asadi. “It’s the best way to close the carbon cycle without losing the chemicals we currently use daily.”

What sets Asadi’s electrolyzer apart is its unique catalytic system. It uses inexpensive, readily available materials to produce tri-carbon molecules — fundamental building blocks for fuels like propane, which is used for purposes ranging from home heating to aviation. To ensure a deep understanding of the catalyst’s operations, the team employed a combination of experimental and computational methods. This rigorous approach illuminated the crucial elements influencing the catalyst’s reaction activity, selectivity, and stability.

A distinctive feature of this technology, lending to its commercial viability, is the implementation of a flow electrolyzer. This design permits continuous propane production, sidestepping the pitfalls of the more conventional batch processing methods.

“Designing and engineering this laboratory-scale flow electrolyzer prototype has demonstrated Illinois Tech’s commitment to creating innovative technologies. Optimizing and scaling up this prototype will be an important step toward producing a sustainable, economically viable, and energy-efficient carbon capture and utilization process,” says Advanced Research Projects Agency-Energy Program Director Jack Lewnard.

This innovation is not Asadi’s first venture into sustainable energy. He previously adapted a version of this catalyst to produce ethanol by harnessing carbon dioxide from industrial waste gas. Recognizing the potential of the green propane technology, Asadi has collaborated with global propane distributor SHV Energy to further scale and disseminate the system.

“This is an exciting development which opens up a new e-fuel pathway to on-purpose propane production for the benefit of global users of this essential fuel,” says Keith Simons, head of research and development for sustainable fuels at SHV Energy.

Mechanisms of hardware and soft technology evolution and the implications for solar energy cost trends

by Magdalena M. Klemun, Goksin Kavlak, James McNerney, Jessika E. Trancik in Nature Energy

To continue reducing the costs of solar energy and other clean energy technologies, scientists and engineers will likely need to focus, at least in part, on improving technology features that are not based on hardware, according to MIT researchers.

While the cost of installing a solar energy system has dropped by more than 99 percent since 1980, this new analysis shows that “soft technology” features, such as the codified permitting practices, supply chain management techniques, and system design processes that go into deploying a solar energy plant, contributed only 10 to 15 percent of total cost declines. Improvements to hardware features were responsible for the lion’s share. But because soft technology is increasingly dominating the total costs of installing solar energy systems, this trend threatens to slow future cost savings and hamper the global transition to clean energy, says the study’s senior author, Jessika Trancik, a professor in MIT’s Institute for Data, Systems, and Society (IDSS).

Trancik’s co-authors include lead author Magdalena M. Klemun, a former IDSS graduate student and postdoc who is now an assistant professor at the Hong Kong University of Science and Technology; Goksin Kavlak, a former IDSS graduate student and postdoc who is now an associate at the Brattle Group; and James McNerney, a former IDSS postdoc and now senior research fellow at the Harvard Kennedy School. The team created a quantitative model to analyze the cost evolution of solar energy systems, which captures the contributions of both hardware technology features and soft technology features.

The framework shows that soft technology hasn’t improved much over time — and that soft technology features contributed even less to overall cost declines than previously estimated. Their findings indicate that to reverse this trend and accelerate cost declines, engineers could look at making solar energy systems less reliant on soft technology to begin with, or they could tackle the problem directly by improving inefficient deployment processes.

“Really understanding where the efficiencies and inefficiencies are, and how to address those inefficiencies, is critical in supporting the clean energy transition. We are making huge investments of public dollars into this, and soft technology is going to be absolutely essential to making those funds count,” says Trancik.

“However,” Klemun adds, “we haven’t been thinking about soft technology design as systematically as we have for hardware. That needs to change.”

Researchers have observed that the so-called “soft costs” of building a solar power plant — the costs of designing and installing the plant — are becoming a much larger share of total costs. In fact, the share of soft costs now typically ranges from 35 to 64 percent.

“We wanted to take a closer look at where these soft costs were coming from and why they weren’t coming down over time as quickly as the hardware costs,” Trancik says.

In the past, scientists have modeled the change in solar energy costs by dividing total costs into additive components — hardware components and nonhardware components — and then tracking how these components changed over time.

“But if you really want to understand where those rates of change are coming from, you need to go one level deeper to look at the technology features. Then things split out differently,” Trancik says.

Estimated contributions from module price variables to cost reduction in residential PV systems in the U.S. Results are shown for the 1980–2017 period and a 5kW system.

The researchers developed a quantitative approach that models the change in solar energy costs over time by assigning contributions to the individual technology features, including both hardware features and soft technology features. For instance, their framework would capture how much of the decline in system installation costs — a soft cost — is due to standardized practices of certified installers — a soft technology feature. It would also capture how that same soft cost is affected by increased photovoltaic module efficiency — a hardware technology feature.

With this approach, the researchers saw that improvements in hardware had the greatest impacts on driving down soft costs in solar energy systems. For example, the efficiency of photovoltaic modules doubled between 1980 and 2017, reducing overall system costs by 17 percent. But about 40 percent of that overall decline could be attributed to reductions in soft costs tied to improved module efficiency. The framework shows that, while hardware technology features tend to improve many cost components, soft technology features affect only a few.

“You can see this structural difference even before you collect data on how the technologies have changed over time. That’s why mapping out a technology’s network of cost dependencies is a useful first step to identify levers of change, for solar PV and for other technologies as well,” Klemun notes.

The researchers used their model to study several countries, since soft costs can vary widely around the world. For instance, solar energy soft costs in Germany are about 50 percent less than those in the U.S. The fact that hardware technology improvements are often shared globally led to dramatic declines in costs over the past few decades across locations, the analysis showed. Soft technology innovations typically aren’t shared across borders. Moreover, the team found that countries with better soft technology performance 20 years ago still have better performance today, while those with worse performance didn’t see much improvement. This country-by-country difference could be driven by regulation and permitting processes, cultural factors, or by market dynamics such as how firms interact with each other, Trancik says.

“But not all soft technology variables are ones that you would want to change in a cost-reducing direction, like lower wages. So, there are other considerations, beyond just bringing the cost of the technology down, that we need to think about when interpreting these results,” she says.

Their analysis points to two strategies for reducing soft costs. For one, scientists could focus on developing hardware improvements that make soft costs more dependent on hardware technology variables and less on soft technology variables, such as by creating simpler, more standardized equipment that could reduce on-site installation time. Or researchers could directly target soft technology features without changing hardware, perhaps by creating more efficient workflows for system installation or automated permitting platforms.

Bridging the Gap between Solar Cells and Batteries: Optical Design of Bifunctional Solar Batteries Based on 2D Carbon Nitrides

by Andreas Gouder, Liang Yao, Yang Wang, Filip Podjaski, Ksenia S. Rabinovich, Alberto Jiménez‐Solano, Bettina V. Lotsch in Advanced Energy Materials

The collaborative effort between the University of Cordoba and the Max Planck Institute for Solid State Research (Germany) is making progress on the design of a solar battery made from an abundant, non-toxic and easily synthesized material composed of 2D carbon nitride.

Solar energy is booming. The improvement of solar technology’s capacity to capture as much light as possible, convert it into energy and make it available to meet energy needs is key in the ecological transition towards a more sustainable use of energy sources.

In the process between the collection of light by the solar cell and the on-demand use of energy of, for instance, household appliances, storage plays a crucial role since the availability of solar energy has an inherent intermittency. To facilitate this storage process and deal with problems such as the environmental impact of the extraction, recycling or scarcity of some of the materials necessary for conventional batteries (such as lithium), the concept of the ‘solar battery’ was born. Solar batteries combine the solar cells that capture light with the storage of its energy in one single device, which then allows the energy to be used when needed.

Alberto Jiménez-Solano, a researcher at the Department of Physics of the University of Cordoba, together with a team from the Max Planck Institute for Solid State Research (Stuttgart, Germany), has carried out a study in which he has explored the design characteristics of a solar battery made from a material based on 2D carbon nitride.

Description and optical challenges that a solid-state solar battery based on K-PHI and PEDOT:PSS provides.

“In Professor Bettina V. Lotsch’s group, at the Max Planck Institute, they had managed to synthesize a material capable of absorbing light and storing that energy for later use on demand,” explains Alberto Jiménez-Solano, “and it occurred to us to use it to create a solar battery.”

To do this, the team first had to find a way to deposit a thin layer of that material (2D potassium carbon nitride, poly(heptazine imide), K-PHI) creating a stable structure to start manufacturing a photovoltaic device due to the fact that that material is normally in powder form or in aqueous suspensions of nanoparticles.

That previous work has now allowed them to present this solar battery design whereby, combining optical simulations and photoelectrochemical experiments, they are able to explain the characteristics of this device’s high performance when capturing sunlight and storing energy.

The physical structure of the device consists of “a high-transparency glass, which has a transparent conductive coating (to allow the transport of load), and a series of layers of semi-transparent materials (with different functionalities), and another conductive glass that closes the circuit,” describes the researcher. It is essentially a kind of sandwich made from various layers whose thicknesses have been studied to maximize both the level of light absorption and storage. In this case, the system they propose can absorb light on both sides since it is semi-transparent. They found that rear lighting had certain advantages; something that they managed to elucidate “by creating an initial theoretical design in accordance with the experimental restrictions” since this basic science project will not remain only on paper, but will also explore the experimental limits, coming up with feasible designs for these solar batteries.

This device would feature great versatility, since it makes it possible to both to obtain a large, one-off current (such as that needed by photography flash), and a smaller current, which could be sustained over time (such as that needed by a mobile phone). This project demonstrates the performance of this device, made from a harmless, abundant, environmentally sustainable material (extracted from urea) which is easy to synthesize. The next steps include continuing to study its operation in various situations outside the laboratory, and adapting it to different manufacturing possibilities and needs.

Artificial spherical chromatophore nanomicelles for selective CO2 reduction in water

by Junlai Yu, Libei Huang, Qingxuan Tang, et al in Nature Catalysis

A joint research team from City University of Hong Kong (CityU) and collaborators recently developed a stable artificial photocatalytic system that is more efficient than natural photosynthesis. The new system mimics a natural chloroplast to convert carbon dioxide in water into methane, a valuable fuel, very efficiently using light. This is a promising discovery, which could contribute to the goal of carbon neutrality.

Photosynthesis is the process by which chloroplasts in plants and some organisms use sunlight, water and carbon dioxide to create food or energy. In past decades, many scientists have tried to develop artificial photosynthesis processes to turn carbon dioxide into carbon-neutral fuel.

“However, it is difficult to convert carbon dioxide in water because many photosensitizers or catalysts degrade in water,” explained Professor Ye Ruquan, Associate Professor in the Department of Chemistry at CityU, one of the leaders of the joint study. “Although artificial photocatalytic cycles have been shown to operate with higher intrinsic efficiency, the low selectivity and stability in water for carbon dioxide reduction have hampered their practical applications.”

In the latest study, the joint-research team from CityU, The University of Hong Kong (HKU), Jiangsu University and the Shanghai Institute of Organic Chemistry of the Chinese Academy of Sciences overcame these difficulties by using a supramolecular assembly approach to create an artificial photosynthetic system. It mimics the structure of a purple bacteria’s light-harvesting chromatophores (i.e. cells that contain pigment), which are very efficient at transferring energy from the sun.

A hierarchical self-assembly photocatalytic system (left) mimics the natural photosynthesis apparatus of a purple bacteria, called Rhodobacter sphaeroides (right), achieving 15% solar-to-fuel efficiency when converting carbon dioxide into methane.

The core of the new artificial photosynthetic system is a highly stable artificial nanomicelle — a kind of polymer that can self-assemble in water, with both a water-loving (hydrophilic) and a water-fearing (hydrophobic) end. The nanomicelle’s hydrophilic head functions as a photosensitizer to absorb sunlight, and its hydrophobic tail acts as an inducer for self-assembly. When it is placed in water, the nanomicelles self-assemble due to intermolecular hydrogen bonding between the water molecules and the tails. Adding a cobalt catalyst results in photocatalytic hydrogen production and carbon dioxide reduction, resulting in the production of hydrogen and methane.

Using advanced imaging techniques and ultrafast spectroscopy, the team unveiled the atomic features of the innovative photosensitizer. They discovered that the special structure of the nanomicelle’s hydrophilic head, along with the hydrogen bonding between water molecules and the nanomicelle’s tail, make it a stable, water-compatible artificial photosensitizer, solving the conventional instability and water-incompatibility problem of artificial photosynthesis. The electrostatic interaction between the photosensitizer and the cobalt catalyst, and the strong light-harvesting antenna effect of the nanomicelle improved the photocatalytic process.

In the experiment, the team found that the methane production rate was more than 13,000 μmol h−1 g−1, with a quantum yield of 5.6% over 24 hours. It also achieved a highly efficient solar-to-fuel efficiency rate of 15%, surpassing natural photosynthesis.

Most importantly, the new artificial photocatalytic system is economically viable and sustainable, as it doesn’t rely on expensive precious metals. “The hierarchical self-assembly of the system offers a promising bottom-up strategy to create a precisely controlled, high-performance artificial photocatalytic system based on cheap, Earth-abundant elements, like zinc and cobalt porphyrin complexes,” said Professor Ye. Professor Ye said he believes the latest discovery will benefit and inspire the rational design of future photocatalytic systems for carbon dioxide conversion and reduction using solar energy, contributing to the goal of carbon neutrality.

Single-cell multimodal imaging uncovers energy conversion pathways in biohybrids

by Bing Fu, Xianwen Mao, Youngchan Park, Zhiheng Zhao, Tianlei Yan, Won Jung, Danielle H. Francis, Wenjie Li, Brooke Pian, Farshid Salimijazi, Mokshin Suri, Tobias Hanrath, Buz Barstow, Peng Chen in Nature Chemistry

When considering ways to sustainably generate environmentally friendly products, bacteria might not immediately spring to mind. However, in recent years scientists have created microbe-semiconductor biohybrids that merge the biosynthetic power of living systems with the ability of semiconductors to harvest light. These microorganisms use solar energy to convert carbon dioxide into value-added chemical products, such as bioplastics and biofuels. But how that energy transport occurs in such a tiny, complex system, and whether the process can be improved, is still unclear.

Cornell University researchers have developed a multimodal platform to image these biohybrids with single-cell resolution, to better understand how they function and how they can be optimized for more efficient energy conversion. The co-lead authors are postdoctoral researcher Bing Fu and former postdoctoral researcher Xianwen Mao. The project was led by Peng Chen, professor of chemistry in the College of Arts and Sciences. The effort is an offshoot of a larger collaboration — with Tobias Hanrath, professor at the Smith School of Chemical and Biomolecular Engineering in Cornell Engineering, and Buz Barstow, assistant professor of biological and environmental engineering in the College of Agriculture and Life Sciences — that was funded by the U.S. Department of Energy (DOE) to explore microscopic imaging of microbes as a way to advance bioenergy research.

Biohybrid research has typically been conducted with bacteria in bulk — essentially a large amount of cells in a bucket, Peng said — emphasizing the overall yield of the value-added chemicals and the collective behaviors of the cells, rather than the underlying mechanism that enables the complex chemical transformation.

A scanning electron microscopy image shows bacterium Ralstonia eutropha cells on top of a bismuth vanadate semiconductor.

“Biology is very heterogeneous. The individual cells are very different. Now, in order to interrogate it better, you really need to measure it at a single-cell level,” Chen said. “This is where we come in. We provide quantitative assessments of protein behaviors and also a mechanistic understanding of how the electron transport occurs from the semiconductor to the bacteria cell.”

The new platform combined multi-channel fluorescence imaging with photoelectrochemical current mapping to survey the bacterium Ralstonia eutropha. The platform was able to simultaneously image, track and quantitate multiple proteins in the cell while also measuring the flow of electrons, ultimately correlating the cellular protein properties and electron transport processes.

The researchers successfully differentiated the functional roles of two types of hydrogenases — one bound to the cell’s membrane, and a soluble one in the cytoplasm — that help metabolize hydrogen and drive CO2 fixation. While the soluble hydrogenase is known to be critical for metabolizing hydrogen, the researchers found that the membrane-bound hydrogenase, while less important, actually facilitates the process and makes it more efficient. In addition, the researchers obtained the first experimental evidence that the bacteriacan uptake a large amount of electrons from semiconductor photocatalysts. The team measured the electron current and found it be three orders of magnitude larger than what scientists previously thought, which suggests that future bacteria strains could be engineered to improve the efficiency of energy conversion.

The researchers also discovered that membrane-bound and soluble hydrogenases play an important role in mediating the electron transport from the semiconductor into the cell. Meanwhile, not only can the cell accept electrons; it can also spit them out in the opposite direction, without the assistance of hydrogenases. The imaging platform is generalizable enough that it can be used to study other biological-inorganic systems, including yeast, and for other processes, such as nitrogen fixation and pollutant removal.

“Our multimodal imaging platform is powerful, but it of course has its own limits,” Chen said. “We can image and study proteins, but our approach does not allow us to analyze small molecule compositions. And so one can think about further integrating our approach with other techniques — for example, nanoscale mass spectrometry — so it would be really powerful. We’re not there yet.”

Electron-rich Ir nanostructure supported on mesoporous Ta2O5 for enhanced activity and stability of oxygen evolution reaction

by Chaekyung Baik, Jinwon Cho, Jeong In Cha, Youngin Cho, Seung Soon Jang, Chanho Pak in Journal of Power Sources

The energy demands of the world are ever increasing. In our quest for clean and eco-friendly energy solutions, transportable hydrogen energy offers considerable promise. In this regard, proton exchange membrane water electrolyzers (PEMWEs) that convert excess electric energy into transportable hydrogen energy through water electrolysis have garnered remarkable interest. However, their widescale deployment for hydrogen production remains limited due to slow rates of oxygen evolution reaction (OER) — an important component of electrolysis — and high loading levels of expensive metal oxide catalysts, such as iridium (Ir) and ruthenium oxides, in electrodes. Therefore, developing cost-effective and high-performance OER catalysts is necessary for the widespread application of PEMWEs.

Recently, a team of researchers from Korea and USA, led by Professor Chanho Pak from Gwangju Institute of Science and Technology in Korea, has developed a novel mesoporous tantalum oxide (Ta2O5)-supported iridium nanostructure catalyst via a modified formic acid reduction method that achieves efficient PEM water electrolysis. The study was co-authored by Dr. Chaekyung Baik, a post-doctoral researcher at Korea Institute of Science and Technology (KIST).

“The electron-rich Ir nanostructure was uniformly dispersed on the stable mesoporous Ta2O5 support prepared via a soft-template method combined with an ethylenediamine encircling process, which effectively decreased the amount of Ir in a single PEMWE cell to 0.3 mg cm-2,” explains Prof. Pak. Importantly, the innovative Ir/Ta2O5 catalyst design not only improved the utilization of Ir but also facilitated higher electrical conductivity and a large electrochemically active surface area.

Additionally, X-ray photoelectron and X-ray absorption spectroscopies revealed strong metal-support interaction between Ir and Ta, while density functional theory calculations indicated a charge transfer from Ta to Ir, which induced the strong binding of adsorbates, such as O and OH, and maintained Ir (III) ratio in the oxidative OER process. This, in turn, led to the enhanced activity of Ir/Ta2O5, with a lower overpotential of 0.385 V compared to a 0.48 V for IrO2.

The team also demonstrated high OER activity of the catalyst experimentally, observing an overpotential of 288 ± 3.9 mV at 10 mA cm-2 and a mass activity of 876.1 ± 125.1 A g-1 of Ir at 1.55 V, significantly higher than the corresponding values for Ir Black. In effect, Ir/Ta2O5 exhibited excellent OER activity and stability, as further confirmed through membrane electrode assembly single cell operation of over 120 hours.

The proposed technology offers the dual benefit of reduced Ir loading levels and an enhanced OER efficiency. “The improved OER efficiency complements the cost-effectiveness of the PEMWE process, enhancing its overall performance. This advancement has the potential to revolutionize the commercialization of PEMWEs, accelerating its adoption as a primary method for hydrogen production,” speculates an optimistic Prof. Pak.

Biorenewable and circular polydiketoenamine plastics

by Jeremy Demarteau, Benjamin Cousineau, Zilong Wang, Baishakhi Bose, Seokjung Cheong, Guangxu Lan, Nawa R. Baral, Simon J. Teat, Corinne D. Scown, Jay D. Keasling, Brett A. Helms in Nature Sustainability

Plastic waste is a problem. Most plastics can’t be recycled, and many use finite, polluting petrochemicals as the basic ingredients. But that’s changing. In a study, researchers successfully engineered microbes to make biological alternatives for the starting ingredients in an infinitely recyclable plastic known as poly(diketoenamine), or PDK.

The finding comes from collaboration among experts at three facilities at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab): the Molecular Foundry, the Joint BioEnergy Institute (JBEI), and the Advanced Light Source.

“This is the first time that bioproducts have been integrated to make a PDK that is predominantly bio-based,” said Brett Helms, staff scientist at the Molecular Foundry who led the project. “And it’s the first time that you see a bio-advantage over using petrochemicals, both with respect to the material’s properties and the cost of producing it at scale.”

Unlike traditional plastics, PDK can be repeatedly deconstructed into pristine building blocks and formed into new products with no loss in quality. PDKs initially used building blocks derived from petrochemicals, but those ingredients can be redesigned and produced with microbes instead. Now, after four years of effort, collaborators have manipulated E. coli to turn sugars from plants into some of the starting materials — a molecule known as triacetic acid lactone, or bioTAL — and produced a PDK with roughly 80% bio-content.

“We’ve demonstrated that the pathway to 100% bio-content in recyclable plastics is feasible,” said Jeremy Demarteau, a project scientist on the team contributing to biopolymer development. “You’ll see that from us in the future.”

PDKs can be used for a variety of products, including adhesives, flexible items like computer cables or watch bands, building materials, and “tough thermosets,” rigid plastics made through a curing process. Researchers were surprised to find that incorporating the bioTAL into the material expanded its working temperature range by up to 60 degrees Celsius compared to the petrochemical version. This opens the door to using PDKs in items that need specific working temperatures, including sports gear and automotive parts such as bumpers or dashboards.

Raw bioTAL (left) can be combined with other chemicals and processed into a biorenewable, recyclable PDK plastic (right).

The United Nations Environment Program estimates that we globally produce about 400 million tons of plastic waste every year, and that number is predicted to climb to more than 1 billion tons by 2050. Of the 7 billion tons of plastic waste already created, only about 10 percent has been recycled, while most is discarded into landfills or burned.

“We can’t keep using our dwindling supply of fossil fuels to feed this insatiable desire for plastics,” said Jay Keasling, a professor at UC Berkeley, senior faculty scientist in Berkeley Lab’s Biosciences Area, and the CEO of JBEI. “We want to help solve the plastic waste problem by creating materials that are both biorenewable and circular — and providing an incentive for companies to use them. Then people could have the products they need for the time they need them, before those items are transformed into something new.”

The study released today also builds on a 2021 environmental and technological analysis, which showed that PDK plastic could be commercially competitive with conventional plastics if produced at a large scale.

“Our new results are extremely encouraging,” said Corinne Scown, a staff scientist in Berkeley Lab’s Energy Technologies Area and a vice president at JBEI. “We found that with even modest improvements to the production process, we could soon be making bio-based PDK plastics that are both cheaper and emit less CO2 than those made with fossil fuels.”

Those improvements would include speeding up the rate at which microbes convert sugars to bioTAL, using bacteria that can transform a wider variety of plant-derived sugars and other compounds, and powering the facility with renewable energy.

Catalytic Fabric Recycling: Glycolysis of Blended PET with Carbon Dioxide and Ammonia

by Yang Yang, Shriaya Sharma, Carlo Di Bernardo, Elisa Rossi, Rodrigo Lima, Fadhil S. Kamounah, Margarita Poderyte, Kasper Enemark-Rasmussen, Gianluca Ciancaleoni, Ji-Woong Lee in ACS Sustainable Chemistry & Engineering

Polyester is the second most used textile in the world and an environmental menace, especially because most of it never gets recycled. The fabric, a blend of plastic and cotton, has been difficult for the industry to separate and therefore recycle. Now, a group of young chemists from the University of Copenhagen has invented a green and surprisingly simple solution using a single household ingredient.

From clothes to sofas to curtains, polyester dominates our everyday lives, with a staggering 60 million tons of this popular fabric produced annually. However, polyester production takes a toll on the climate and the environment, as only a mere 15% of it is recycled, while the rest ends up in landfills or incinerated, being responsible of more carbon emission.

Recycling polyester poses a significant challenge, particularly in separating the plastic and cotton fibers that the blend fabric is made of without losing either of them in the process. Conventional recycling methods often prioritize preserving the plastic component, resulting in a loss of cotton fibers. Moreover, these methods are costly, complex, and generate metal waste due to the use of metal catalysts, which can be cytotoxic and contaminate the process.

In a remarkable breakthrough, a group of young chemists has unveiled a surprisingly simple solution to this pressing problem, potentially revolutionizing the sustainability of the textile industry.

“The textile industry urgently requires a better solution to handle blended fabrics like polyester/cotton. Currently, there are very few practical methods capable of recycling both cotton and plastic — it’s typically an either-or scenario. However, with our newly discovered technique, we can depolymerize polyester into its monomers while simultaneously recovering cotton on a scale of hundreds of grams, using an incredibly straightforward and environmentally friendly approach. This traceless catalytic methodology could be the game-changer,” explains postdoc Yang Yang of the Jiwoong Lee group at the University of Copenhagen’s Department of Chemistry, who serves as the lead author of the scientific research article.

The new method requires no special equipment — just heat, a non-toxic solvent, and an ordinary household ingredient.

“For example, we can take a polyester dress, cut it up into small pieces and place it in a container. Then, add a bit of mild solvent, and thereafter hartshorn salt, which many people know as a leavening agent in baked goods. We then heat it all up to 160 degrees Celsius and leave it for 24 hours. The result is a liquid in which the plastic and cotton fibers settle into distinct layers. It’s a simple and cost-effective process,” explains Shriaya Sharma, a doctoral student of the Jiwoong Lee group at the Department of Chemistry and study co-author.

In the process, the hartshorn salt, also called ammonium bicarbonate, is broken down into ammonia, CO2 and water. The combination of ammonia and CO2 acts as a catalyst, triggering a selective depolymerization reaction that breaks down the polyester while preserving the cotton fibers. Although ammonia is toxic in isolation, when combined with CO2, it becomes both environmentally friendly and safe for use. Due to the mild nature of the chemicals involved, the cotton fibers remain intact and in excellent condition.

Previously, the same research group demonstrated that CO2 could serve as a catalyst for breaking down nylon, among other things, without leaving any trace. This discovery inspired them to explore the use of hartshorn salt. Nevertheless, the researchers were pleasantly surprised when their simple recipe yielded successful results.

“At first, we were excited to see it work so well on the PET bottles alone. Then, when we discovered that it worked on polyester fabric as well, we were just ecstatic. It was indescribable. That it was so simple to perform was nearly too good to be true,” says Carlo Di Bernardo, doctoral student and study co-author.

While the method has only been tested at the laboratory level thus far, the researchers point to its scalability and are now in contact with companies to test the method on an industrial scale.

“We’re hoping to commercialize this technology that harbors such great potential. Keeping this knowledge behind the walls of the university would be a huge waste,” concludes Yang Yang.

Renewable energies and biodiversity: Impact of ground‐mounted solar photovoltaic sites on bat activity

by Elizabeth Tinsley, Jérémy S. P. Froidevaux, Sándor Zsebők, Kriszta Lilla Szabadi, Gareth Jones in Journal of Applied Ecology

The activity level of six bat species was significantly reduced at solar farm sites, researchers have observed. Their findings have the potential to impact and inform planning legislation and policy so that the benefits of solar power are reaped without impacting wildlife.

Renewable technologies are important in meeting energy demands sustainably. This is of vital importance given the roles of fossil fuels in producing carbon dioxide, a key driver of climate change. Renewable energy is growing at a rapid pace globally, with solar photovoltaic power providing about 30% of global renewable power, and increasing in amount by 25% in 2021.

Lead author Lizy Tinsley from the University of Bristol’s School of Biological Sciences explained: “Renewable energies can have negative impacts on biodiversity and mitigation is essential to provide win-win solutions for energy suppliers and for wildlife.”

To carry out their experiment, the team set up bat static monitoring equipment in a solar farm field, and a matched field without solar panels (control site).

Fields were matched in size, land use, and boundary feature (e.g. hedge, fence, stream) and a bat detector was placed in the middle and edge of both fields, totalling four recording locations, repeated across 19 separate sites. Field boundaries were selected as they are important navigation features for bats. The data from the different echolocation calls at recording points were then analysed to identify the bat species and number of bat passes. They found that the activity level of Common Pipistrelle, Noctule, Myotis species, Serotine, Soprano pipistrelle and Long-eared species was substantially lower at solar farm sites, compared to the paired control sites.

Lizy said: “Due to the significant negative impact identified, solar farm developments should be screened in an Environmental Impact Assessment for ecological impacts so that appropriate mitigation be designed against the impacts, and monitoring undertaken.

“This has already been done with wind farms — where mortality of bats has been reduced by changing the wind speeds at which turbines become operational and by using acoustic deterrents, at minimal cost.

Boxplots showing medians and interquartile ranges of species-specific bat activity (i.e. total number of bat call sequences per site on a logarithmic scale to the base 2) at control and solar PV sites. Dots represent raw data with paired sites linked with a grey line. **p < 0.01 and *p < 0.05.

“Further research is required to assess bat behaviour at solar farms, and why it is causing the significant decrease of certain species at the site. Is it the loss of suitable habitat that reduces activity? Are they fewer insect prey available, and are bats at risk of collisions with panels?

“It will be important to identify mitigation strategies that can benefit bats at solar farms, such as planting insect-friendly plants, providing corridors to insect-rich habitats, or providing suitable alternative foraging habitats such as trees.

“Mitigation strategies can potentially mean that renewable energy can be provided while simultaneously having no detriment to wildlife. Such mitigation will be critical in reaping the undoubted benefits for climate change that can be provided by renewable energy.”

Carbon–cement supercapacitors as a scalable bulk energy storage solution

by Nicolas Chanut, Damian Stefaniuk, James C. Weaver, Yunguang Zhu, Yang Shao-Horn, Admir Masic, Franz-Josef Ulm in Proceedings of the National Academy of Sciences

Two of humanity’s most ubiquitous historical materials, cement and carbon black (which resembles very fine charcoal), may form the basis for a novel, low-cost energy storage system, according to a new study. The technology could facilitate the use of renewable energy sources such as solar, wind, and tidal power by allowing energy networks to remain stable despite fluctuations in renewable energy supply.

The two materials, the researchers found, can be combined with water to make a supercapacitor — an alternative to batteries — that could provide storage of electrical energy. As an example, the MIT researchers who developed the system say that their supercapacitor could eventually be incorporated into the concrete foundation of a house, where it could store a full day’s worth of energy while adding little (or no) to the cost of the foundation and still providing the needed structural strength. The researchers also envision a concrete roadway that could provide contactless recharging for electric cars as they travel over that road. The simple but innovative technology is described in a paper by MIT professors Franz-Josef Ulm, Admir Masic, and Yang-Shao Horn, and four others at MIT and at the Wyss Institute.

Capacitors are in principle very simple devices, consisting of two electrically conductive plates immersed in an electrolyte and separated by a membrane. When a voltage is applied across the capacitor, positively charged ions from the electrolyte accumulate on the negatively charged plate, while the positively charged plate accumulates negatively charged ions. Since the membrane in between the plates blocks charged ions from migrating across, this separation of charges creates an electric field between the plates, and the capacitor becomes charged. The two plates can maintain this pair of charges for a long time and then deliver them very quickly when needed. Supercapacitors are simply capacitors that can store exceptionally large charges.

The amount of power a capacitor can store depends on the total surface area of its conductive plates. The key to the new supercapacitors developed by this team comes from a method of producing a cement-based material with an extremely high internal surface area due to a dense, interconnected network of conductive material within its bulk volume. The researchers achieved this by introducing carbon black — which is highly conductive — into a concrete mixture along with cement powder and water, and letting it cure. The water naturally forms a branching network of openings within the structure as it reacts with cement, and the carbon migrates into these spaces to make wire-like structures within the hardened cement. These structures have a fractal-like structure, with larger branches sprouting smaller branches, and those sprouting even smaller branchlets, and so on, ending up with an extremely large surface area within the confines of a relatively small volume. The material is then soaked in a standard electrolyte material, such as potassium chloride, a kind of salt, which provides the charged particles that accumulate on the carbon structures. Two electrodes made of this material, separated by a thin space or an insulating layer, form a very powerful supercapacitor, the researchers found.

Correlative EDS–Raman Spectroscopy analysis.

The two plates of the capacitor function just like the two poles of a rechargeable battery of equivalent voltage: When connected to a source of electricity, as with a battery, energy gets stored in the plates, and then when connected to a load, the electrical current flows back out to provide power.

“The material is fascinating,” Masic says, “because you have the most-used human-made material in the world, cement, that is combined with carbon black, that is a well-known historical material — the Dead Sea Scrolls were written with it. You have these at least two-millennia-old materials that when you combine them in a specific manner you come up with a conductive nanocomposite, and that’s when things get really interesting.”

As the mixture sets and cures, he says, “The water is systematically consumed through cement hydration reactions, and this hydration fundamentally affects nanoparticles of carbon because they are hydrophobic (water repelling).” As the mixture evolves, “the carbon black is self-assembling into a connected conductive wire,” he says. The process is easily reproducible, with materials that are inexpensive and readily available anywhere in the world. And the amount of carbon needed is very small — as little as 3 percent by volume of the mix — to achieve a percolated carbon network, Masic says.

Supercapacitors made of this material have great potential to aid in the world’s transition to renewable energy, Ulm says. The principal sources of emissions-free energy, wind, solar, and tidal power, all produce their output at variable times that often do not correspond to the peaks in electricity usage, so ways of storing that power are essential. “There is a huge need for big energy storage,” he says, and existing batteries are too expensive and mostly rely on materials such as lithium, whose supply is limited, so cheaper alternatives are badly needed. “That’s where our technology is extremely promising, because cement is ubiquitous,” Ulm says.

The team calculated that a block of nanocarbon-black-doped concrete that is 45 cubic meters (or yards) in size — equivalent to a cube about 3.5 meters across — would have enough capacity to store about 10 kilowatt-hours of energy, which is considered the average daily electricity usage for a household. Since the concrete would retain its strength, a house with a foundation made of this material could store a day’s worth of energy produced by solar panels or windmills and allow it to be used whenever it’s needed. And, supercapacitors can be charged and discharged much more rapidly than batteries.

After a series of tests used to determine the most effective ratios of cement, carbon black, and water, the team demonstrated the process by making small supercapacitors, about the size of some button-cell batteries, about 1 centimeter across and 1 millimeter thick, that could each be charged to 1 volt, comparable to a 1-volt battery. They then connected three of these to demonstrate their ability to light up a 3-volt light-emitting diode (LED). Having proved the principle, they now plan to build a series of larger versions, starting with ones about the size of a typical 12-volt car battery, then working up to a 45-cubic-meter version to demonstrate its ability to store a house-worth of power.

There is a tradeoff between the storage capacity of the material and its structural strength, they found. By adding more carbon black, the resulting supercapacitor can store more energy, but the concrete is slightly weaker, and this could be useful for applications where the concrete is not playing a structural role or where the full strength-potential of concrete is not required. For applications such as a foundation, or structural elements of the base of a wind turbine, the “sweet spot” is around 10 percent carbon black in the mix, they found.

Another potential application for carbon-cement supercapacitors is for building concrete roadways that could store energy produced by solar panels alongside the road and then deliver that energy to electric vehicles traveling along the road using the same kind of technology used for wirelessly rechargeable phones. A related type of car-recharging system is already being developed by companies in Germany and the Netherlands, but using standard batteries for storage.

Initial uses of the technology might be for isolated homes or buildings or shelters far from grid power, which could be powered by solar panels attached to the cement supercapacitors, the researchers say.

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