GT/ Next-generation batteries could go organic, cobalt-free for long-lasting power
Energy & green technology biweekly vol.62, 11th January — 25th January
TL;DR
- In the switch to ‘greener’ energy sources, the demand for rechargeable lithium-ion batteries is surging. However, their cathodes typically contain cobalt — a metal whose extraction has high environmental and societal costs. Now, researchers in report evaluating an earth-abundant, carbon-based cathode material that could replace cobalt and other scarce and toxic metals without sacrificing lithium-ion battery performance.
- A research team has achieved remarkable advancements in the stability and efficiency of perovskite solar cells.
- Researchers have developed a framework that uses machine learning to accelerate the search for new proton-conducting materials, that could potentially improve the efficiency of hydrogen fuel cells.
- Researchers developed literal ‘power plants’ — tiny, leaf-shaped generators that create electricity from a blowing breeze or falling raindrops. The team tested the energy harvesters by incorporating them into artificial plants.
- A research team has developed a novel catalyst for the high-efficiency and stable production of high-purity green hydrogen.
- Scientists have developed a way to convert carbon dioxide, a potent greenhouse gas, into carbon nanofibers, materials with a wide range of unique properties and many potential long-term uses. Their strategy uses tandem electrochemical and thermochemical reactions run at relatively low temperatures and ambient pressure and could successfully lock carbon away to offset or even achieve negative carbon emissions.
- A study has found that green ammonia could be used to fulfill the fuel demands of over 60% of global shipping by targeting just the top 10 regional fuel ports. Researchers looked at the production costs of ammonia which are similar to very low sulphur fuels, and concluded that the fuel could be a viable option to help decarbonize international shipping by 2050.
- Scientists use light-reactive molecules to influence the acidity of a liquid and thereby capture of carbon dioxide. They have developed a special mixture of different solvents to ensure that the light-reactive molecules remain stable over a long period of time. Conventional carbon capture technologies are driven by temperature or pressure differences and require a lot of energy. This is no longer necessary with the new light-based process.
- Researchers are tapping into idled electric vehicles to act as mobile generators and help power overworked and aging electricity grids. After analyzing energy demand on Alberta’s power grid during rush hour, the research proposes an innovative way to replenish electrical grids with power generated from fuel cells in trucks.
- Engineers have succeeded in implementing a stretchable organic solar cell by applying a newly developed polymer material that demonstrated the world’s highest photovoltaic conversion efficiency (19%) while functioning even when stretched for more than 40% of its original state. This new conductive polymer has high photovoltaic properties that can be stretched like rubber. The newly developed polymer is expected to play a role as a power source for next-generation wearable electronic devices.
- 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
A Layered Organic Cathode for High-Energy, Fast-Charging, and Long-Lasting Li-Ion Batteries
by Tianyang Chen, Harish Banda, Jiande Wang, Julius J. Oppenheim, Alessandro Franceschi, Mircea Dincǎ in ACS Central Science
In the switch to “greener” energy sources, the demand for rechargeable lithium-ion batteries is surging. However, their cathodes typically contain cobalt — a metal whose extraction has high environmental and societal costs. Now, researchers report evaluating an earth-abundant, carbon-based cathode material that could replace cobalt and other scarce and toxic metals without sacrificing lithium-ion battery performance.
Today, lithium-ion batteries power everything from cell phones to laptops to electric vehicles. One of the limiting factors for realizing a global shift to energy produced by renewable sources — particularly for the transition from gasoline-powered cars to electric vehicles — is the scarcity and mining difficulty of the metals, such as cobalt, nickel and magnesium, used in rechargeable battery cathode manufacturing. Previous researchers have developed cathodes from more abundant and lower cost carbon-containing materials, including organosulfur and carbonyl compounds, but those prototypes couldn’t match the energy output and stability of traditional lithium-ion batteries.
So, Mircea Dincǎ and his colleagues wanted to see if other carbon-based cathode materials could be more successful. They may have found a worthy candidate in bis-tetraaminobenzoquinone (TAQ). TAQ molecules form layered solid-state structures than can potentially compete with traditional cobalt-based cathode performance.
Building on their prior work that showed TAQ’s effectiveness as a supercapacitor material, Dincǎ’s team tested the compound in a cathode for lithium-ion batteries. To improve cycling stability and to increase TAQ adhesion to the cathode’s stainless-steel current collector, they added cellulose- and rubber-containing materials to the TAQ cathode. In the researchers’ proof-of-concept demonstration, the new composite cathode cycled safely more than 2,000 times, delivered an energy density higher than most cobalt-based cathodes and charged-discharged in as little as six minutes.
The TAQ-based cathodes need additional testing before they appear on the market, but the researchers are optimistic that they could enable the high-energy, long-lasting and fast-charging batteries needed to help speed a global transition to a renewable energy future that’s cobalt- and nickel-free.
Efficient and Stable Tin–Lead Perovskite Photoconversion Devices Using Dual‐Functional Cathode Interlayer
by Muhibullah Al Mubarok, Yuri Choi, Rashmi Mehrotra, Yu Jin Kim, Rama Krishna Boddu, Inhui Lee, Jiyeong Kim, Sang Kyu Kwak, Ji‐Wook Jang, Jungki Ryu, Sung‐Yeon Jang in Advanced Energy Materials
A team of researchers from the School of Energy and Chemical Engineering at UNIST, jointly led by Professors Sung-Yeon Jang, Jungki Ryu, and Ji-Wook Jang, in collaboration with Professor Sang Kyu Kwak from Korea University, have achieved remarkable advancements in the stability and efficiency of perovskite solar cells. Their groundbreaking work not only paves the way for the commercialization of perovskite solar cells (PSCs), but also offers significant potential in green hydrogen production technology, ensuring long-term operation with high efficiency.
Perovskite solar cells (PSCs) have garnered attention due to their reduced toxicity and broad light absorption capabilities, making them highly promising for photovoltaic applications. However, the presence of inherent ionic vacancies in tin-lead halide perovskites (TLHPs) has posed challenges, leading to accelerated device degradation through inward metal diffusion.
To address this challenge, the research team developed a chemically protective cathode interlayer using amine-functionalized perylene diimide (PDINN). By leveraging its nucleophilic sites to form tridentate metal complexes, PDINN effectively extracts electrons and suppresses inward metal diffusion. The novel solution-processed PDINN cathode interlayer has showcased remarkable performance in stabilizing TLHP-based photovoltaic (PV) and photoelectrochemical (PEC) devices.
The PV device achieved an impressive efficiency of 23.21%, with over 81% retention after 750 hours of operation at 60 °C, and more than 90% retention after 3100 hours at 23 ± 4 °C. Additionally, the TLHP-based PEC devices, coupled with biomass oxidation, exhibited a record-high bias-free solar hydrogen production rate of 33.0 mA cm−2, approximately 1.7-fold higher than the target set by the U.S. Department of Energy for one-sun hydrogen production.
Their innovative design of the cathode interlayer has successfully demonstrated the immense potential of TLHPs for efficient and stable photoconversion.
“We have dramatically increased the long-term stability of tin-lead PSCs,” explained Professor Jang. “Our goal is not only to convert light energy into electrical energy but also to develop eco-friendly methods for producing basic chemicals, such as hydrogen, which form the foundation of various industries.”
Discovery of Unconventional Proton‐Conducting Inorganic Solids via Defect‐Chemistry‐Trained, Interpretable Machine Learning
by Susumu Fujii, Yuta Shimizu, Junji Hyodo, Akihide Kuwabara, Yoshihiro Yamazaki in Advanced Energy Material
Researchers at Kyushu University, in collaboration with Osaka University and the Fine Ceramics Center, have developed a framework that uses machine learning to speed up the discovery of materials for green energy technology. Using the new approach, the researchers identified and successfully synthesized two new candidate materials for use in solid oxide fuel cells — devices that can generate energy using fuels like hydrogen, which don’t emit carbon dioxide. Their findings could also be used to accelerate the search for other innovative materials beyond the energy sector.
In response to a warming climate, researchers have been developing new ways to generate energy without using fossil fuels. “One path to carbon neutrality is by creating a hydrogen society. However, as well as optimizing how hydrogen is made, stored and transported, we also need to boost the power-generating efficiency of hydrogen fuel cells,” explains Professor Yoshihiro Yamazaki, of Kyushu University’s Department of Materials Science and Technology, Platform of Inter-/Transdisciplinary Energy Research (Q-PIT).
To generate an electric current, solid oxide fuel cells need to be able to efficiently conduct hydrogen ions (or protons) through a solid material, known as an electrolyte. Currently, research into new electrolyte materials has focused on oxides with very specific crystal arrangements of atoms, known as a perovskite structure.
“The first proton-conducting oxide discovered was in a perovskite structure, and new high-performing perovskites are continually being reported,” says Professor Yamazaki. “But we want to expand the discovery of solid electrolytes to non-perovskite oxides, which also have the capability of conducting protons very efficiently.”
However, discovering proton-conducting materials with alternative crystal structures via traditional “trial and error” methods has numerous limitations. For an electrolyte to gain the ability to conduct protons, small traces of another substance, known as a dopant, must be added to the base material. But with many promising base and dopant candidates — each with different atomic and electronic properties — finding the optimal combination that enhances proton conductivity becomes difficult and time-consuming.
Instead, the researchers calculated the properties of different oxides and dopants. They then used machine learning to analyze the data, identify the factors that impact the proton conductivity of a material, and predict potential combinations.
Guided by these factors, the researchers then synthesized two promising materials, each with unique crystal structures, and assessed how well they conducted protons. Remarkably, both materials demonstrated proton conductivity in just a single experiment. One of the materials, the researchers highlighted, is the first-known proton conductor with a sillenite crystal structure. The other, which has a eulytite structure, has a high-speed proton conduction path that is distinct from the conduction paths seen in perovskites. Currently, the performance of these oxides as electrolytes is low, but with further exploration, the research team believes their conductivity can be improved.
“Our framework has the potential to greatly expand the search space for proton-conducting oxides, and therefore significantly accelerate advancements in solid oxide fuel cells. It’s a promising step forward to realizing a hydrogen society,” concludes Professor Yamazaki. “With minor modifications, this framework could also be adapted to other fields of materials science, and potentially accelerate the development of many innovative materials.”
Multisource Energy Harvester on Textile and Plants for Clean Energy Generation from Wind and Rainwater Droplets
by Guanbo Min, Gaurav Khandelwal, Abhishek Singh Dahiya, Shashank Mishra, Wei Tang, Ravinder Dahiya in ACS Sustainable Chemistry & Engineering
Fake plants are moving into the 21st century! Researchers developed literal “power plants” — tiny, leaf-shaped generators that create electricity from a blowing breeze or falling raindrops. The team tested the energy harvesters by incorporating them into artificial plants.
Electrical energy can be produced from nature in several ways. For example, solar panels convert light energy from the sun, and wind turbines transform the kinetic energy of moving air. But these methods typically rely on a single source and therefore are only effective when that source is available. Solar panels don’t work after sunset, for example, and a calm day won’t generate much wind power. More recently, multi-source energy harvesters have emerged as a method to capture energy from different renewable sources in one device, maximizing potential output. So, Ravinder Dahiya and colleagues wanted to create a multi-source energy harvester that could generate power from both wind and rain.
The team built two different types of energy collectors: a triboelectric nanogenerator (TENG) to capture kinetic energy from the wind and a droplet-based energy generator (DEG) to collect energy from falling raindrops. The TENG consisted of a layer of nylon nanofibers sandwiched between layers of polytetrafluoroethylene, more commonly known as Teflon™, and copper electrodes. When the layers pressed into each other, static charges were generated and converted into electricity. Teflon was also used to make the DEG, which was waterproofed and covered with a conductive fabric to act as the electrodes. As raindrops hit one of the electrodes, it caused an imbalance in charges, generating a small current and high voltage. Under optimal conditions, the TENG produced 252 volts of power and the DEG 113 volts, but only for short periods of time.
The team mounted the DEG atop the TENG and incorporated leaf-shaped versions into an artificial plant. When the leaf-shaped generators were exposed to conditions mimicking natural wind and rain, they powered 10 LED lights in short flickers. This proof-of-concept “power plant” device could be further developed into larger systems or networks of power plants to produce clean energy from natural sources, the researchers say.
Electrochemical Evolution of Ru‐Based Polyoxometalates into Si,W‐Codoped RuOx for Acidic Overall Water Splitting
by Dasom Jeon, Dong Yeon Kim, Hyeongoo Kim, Nayeong Kim, Cheolmin Lee, Dong‐Hwa Seo, Jungki Ryu in Advanced Materials
A breakthrough technology has been developed that enables the production of green hydrogen in a more cost-effective and environmentally friendly manner, bringing us closer to a carbon-neutral society by replacing expensive precious metal catalysts.
Led by Professor Jungki Ryu in the School of Energy and Chemical Engineering at UNIST and Professor Dong-Hwa Seo from the Department of Materials Science and Engineering at KAIST, a joint research team has successfully developed a bifunctional water electrolysis catalyst for the high-efficiency and stable production of high-purity green hydrogen.
The newly-developed catalyst exhibits exceptional durability even in highly corrosive acidic environments. By utilizing ruthenium, silicon, and tungsten (RuSiW), the catalyst is more cost-effective compared to conventional platinum (Pt) or iridium (Ir) catalysts. Furthermore, it emits significantly fewer greenhouse gases, making it an eco-friendly alternative.
Water electrolysis is a cutting-edge technology that produces hydrogen through the process of electrolyzing water. It is considered a key technology for achieving a carbon-neutral society as it enables the production of environmentally friendly hydrogen without carbon emissions.
The research team focused on finding alternatives to precious metal catalysts like platinum and iridium, which exhibit stability in acidic conditions. Ruthenium has gained attention as an eco-friendly metal due to its relatively low production cost and significantly lower greenhouse gas emissions compared to platinum and iridium. However, it faced challenges in commercialization due to its lower catalytic activity compared to platinum and lower stability compared to iridium.
To overcome these limitations, the research team developed a catalyst based on ruthenium, silicon, and tungsten. By enhancing the function of the ruthenium catalyst, which has lower stability in both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), the team demonstrated the catalyst’s potential as a bifunctional catalyst.
The developed catalyst features a structure doped with tungsten and silicon around a ruthenium atom. The catalyst’s reaction acceleration ability was enhanced by increasing the adsorption intensity of protons on the catalyst surface. It exhibits higher activity in the hydrogen evolution reaction compared to commercially available platinum catalysts. Additionally, a thin tungsten film with a thickness of 5~10 nm protects the catalytic site of ruthenium, thereby improving its stability.
The research team conducted a stability experiment on the catalyst. Using an acidic electrolyte (with an acidity of 0.3), they injected 10 mA of current into a 1 ? electrode. The developed catalyst demonstrated stable performance even after running for over 100 hours.
Professor Ryu stated, “The development of this three-element catalyst is significant as it has the potential to replace expensive platinum and iridium simultaneously. It is expected to be applied to high-purity green hydrogen production systems, such as PEM electrolyzers, as it can be easily and stably synthesized even in highly corrosive acidic conditions.”
CO2 fixation into carbon nanofibres using electrochemical–thermochemical tandem catalysis
by Zhenhua Xie, Erwei Huang, Samay Garg, Sooyeon Hwang, Ping Liu, Jingguang G. Chen in Nature Catalysis
Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and Columbia University have developed a way to convert carbon dioxide (CO2), a potent greenhouse gas, into carbon nanofibers, materials with a wide range of unique properties and many potential long-term uses. Their strategy uses tandem electrochemical and thermochemical reactions run at relatively low temperatures and ambient pressure. As the scientists describe, this approach could successfully lock carbon away in a useful solid form to offset or even achieve negative carbon emissions.
“You can put the carbon nanofibers into cement to strengthen the cement,” said Jingguang Chen, a professor of chemical engineering at Columbia with a joint appointment at Brookhaven Lab who led the research. “That would lock the carbon away in concrete for at least 50 years, potentially longer. By then, the world should be shifted to primarily renewable energy sources that don’t emit carbon.”
As a bonus, the process also produces hydrogen gas (H2), a promising alternative fuel that, when used, creates zero emissions. The idea of capturing CO2 or converting it to other materials to combat climate change is not new. But simply storing CO2 gas can lead to leaks. And many CO2 conversions produce carbon-based chemicals or fuels that are used right away, which releases CO2 right back into the atmosphere.
“The novelty of this work is that we are trying to convert CO2 into something that is value-added but in a solid, useful form,” Chen said.
Such solid carbon materials — including carbon nanotubes and nanofibers with dimensions measuring billionths of a meter — have many appealing properties, including strength and thermal and electrical conductivity. But it’s no simple matter to extract carbon from carbon dioxide and get it to assemble into these fine-scale structures. One direct, heat-driven process requires temperatures in excess of 1,000 degrees Celsius.
“It’s very unrealistic for large-scale CO2 mitigation,” Chen said. “In contrast, we found a process that can occur at about 400 degrees Celsius, which is a much more practical, industrially achievable temperature.”
The trick was to break the reaction into stages and to use two different types of catalysts — materials that make it easier for molecules to come together and react.
“If you decouple the reaction into several sub-reaction steps you can consider using different kinds of energy input and catalysts to make each part of the reaction work,” said Brookhaven Lab and Columbia research scientist Zhenhua Xie, lead author on the paper.
The scientists started by realizing that carbon monoxide (CO) is a much better starting material than CO2 for making carbon nanofibers (CNF). Then they backtracked to find the most efficient way to generate CO from CO2.
Earlier work from their group steered them to use a commercially available electrocatalyst made of palladium supported on carbon. Electrocatalysts drive chemical reactions using an electric current. In the presence of flowing electrons and protons, the catalyst splits both CO2 and water (H2O) into CO and H2. For the second step, the scientists turned to a heat-activated thermocatalyst made of an iron-cobalt alloy. It operates at temperatures around 400 degrees Celsius, significantly milder than a direct CO2-to-CNF conversion would require. They also discovered that adding a bit of extra metallic cobalt greatly enhances the formation of the carbon nanofibers.
“By coupling electrocatalysis and thermocatalysis, we are using this tandem process to achieve things that cannot be achieved by either process alone,” Chen said.
To discover the details of how these catalysts operate, the scientists conducted a wide range of experiments. These included computational modeling studies, physical and chemical characterization studies at Brookhaven Lab’s National Synchrotron Light Source II (NSLS-II) — using the Quick X-ray Absorption and Scattering (QAS) and Inner-Shell Spectroscopy (ISS) beamlines — and microscopic imaging at the Electron Microscopy facility at the Lab’s Center for Functional Nanomaterials (CFN).
On the modeling front, the scientists used “density functional theory” (DFT) calculations to analyze the atomic arrangements and other characteristics of the catalysts when interacting with the active chemical environment.
“We are looking at the structures to determine what are the stable phases of the catalyst under reaction conditions,” explained study co-author Ping Liu of Brookhaven’s Chemistry Division who led these calculations. “We are looking at active sites and how these sites are bonding with the reaction intermediates. By determining the barriers, or transition states, from one step to another, we learn exactly how the catalyst is functioning during the reaction.”
X-ray diffraction and x-ray absorption experiments at NSLS-II tracked how the catalysts change physically and chemically during the reactions. For example, synchrotron x-rays revealed how the presence of electric current transforms metallic palladium in the catalyst into palladium hydride, a metal that is key to producing both H2 and CO in the first reaction stage.
For the second stage, “We wanted to know what’s the structure of the iron-cobalt system under reaction conditions and how to optimize the iron-cobalt catalyst,” Xie said. The x-ray experiments confirmed that both an alloy of iron and cobalt plus some extra metallic cobalt are present and needed to convert CO to carbon nanofibers.
“The two work together sequentially,” said Liu, whose DFT calculations helped explain the process. “According to our study, the cobalt-iron sites in the alloy help to break the C-O bonds of carbon monoxide. That makes atomic carbon available to serve as the source for building carbon nanofibers. Then the extra cobalt is there to facilitate the formation of the C-C bonds that link up the carbon atoms,” she explained.
“Transmission electron microscopy (TEM) analysis conducted at CFN revealed the morphologies, crystal structures, and elemental distributions within the carbon nanofibers both with and without catalysts,” said CFN scientist and study co-author Sooyeon Hwang.
The images show that, as the carbon nanofibers grow, the catalyst gets pushed up and away from the surface. That makes it easy to recycle the catalytic metal, Chen said.
“We use acid to leach the metal out without destroying the carbon nanofiber so we can concentrate the metals and recycle them to be used as a catalyst again,” he said.
This ease of catalyst recycling, commercial availability of the catalysts, and relatively mild reaction conditions for the second reaction all contribute to a favorable assessment of the energy and other costs associated with the process, the researchers said.
Optimal fuel supply of green ammonia to decarbonise global shipping
by Jasper Verschuur, Nicholas Salmon, Jim Hall, René Bañares-Alcántara in Environmental Research: Infrastructure and Sustainability
A study has found that green ammonia could be used to fulfil the fuel demands of over 60% of global shipping by targeting just the top 10 regional fuel ports. Researchers at the University of Oxford looked at the production costs of ammonia which are similar to very low sulphur fuels, and concluded that the fuel could be a viable option to help decarbonise international shipping by 2050.
Around USD 2 trillion will be needed to transition to a green ammonia fuel supply chain by 2050, primarily to finance supply infrastructure. The study shows that the greatest investment need is in Australia, to supply the Asian markets, with large production clusters also predicted in Chile (to supply South America), California (to supply Western U.S.A.), North-West Africa (to meet European demand), and the southern Arabian Peninsula (to meet local demand and parts of south Asia).
90% of world’s physical goods trade is transported by ships which burn heavy fuel oil and emit toxic pollutants. This accounts for nearly 3% of the global greenhouse gas (GHG) emissions. As a result of this, the International Maritime Organization (IMO) committed to decarbonising international shipping in 2018, aiming to halve GHG emissions by 2050. These targets have been recently revised to net zero emissions by 2050.
After investigating the viability of diesel vessel exhaust scrubbers, green ammonia, made by electrolysing water with renewable electricity, was proposed as an alternative fuel source to quickly decarbonise the shipping industry. However, historically there has been great uncertainty as to how and where to invest to create the necessary infrastructure to deliver an efficient, viable fuel supply chain.
René Bañares-Alcántara, Professor of Chemical Engineering in the Department of Engineering Science at the University of Oxford, says: “Shipping is one of the most challenging sectors to decarbonize because of the need for fuel with high energy density and the difficulty of coordinating different groups to produce, utilize and finance alternative (green) fuel supplies.”
To guide investors, the team at the University of Oxford developed a modelling framework to create viable scenarios for how to establish a global green ammonia fuel supply chain. The framework combines a fuel demand model, future trade scenarios and a spatial optimisation model for green ammonia production, storage, and transport, to find the best locations to meet future demand for shipping fuel.
Solvation-Tuned Photoacid as a Stable Light-Driven pH Switch for CO2 Capture and Release
by Anna de Vries, Kateryna Goloviznina, Manuel Reiter, Mathieu Salanne, Maria R. Lukatskaya in Chemistry of Materials
If we want to slow down global warming, we need to drastically reduce greenhouse gas emissions. Among other things, we need to do without fossil fuels and use more energy-efficient technologies. However, reducing emissions alone won’t do enough to meet the climate targets. We must also capture large quantities of the greenhouse gas CO2 from the atmosphere and either store it permanently underground or use it as a carbon-neutral feed material in industry. Unfortunately, the carbon capture technologies available today require a lot of energy and are correspondingly expensive.
That’s why researchers at ETH Zurich are developing a new method that uses light. With this process, in the future, the energy required for carbon capture will come from the sun. Led by Maria Lukatskaya, Professor of Electrochemical Energy Systems, the scientists are exploiting the fact that in acidic aqueous liquids, CO2 is present as CO2, but in alkaline aqueous liquids, it reacts to form salts of carbonic acid, known as carbonates. This chemical reaction is reversible. A liquid’s acidity determines whether it contains CO2 or a carbonate.
To influence the acidity of their liquid, the researchers added molecules, called photoacids, to it that react to light. If such liquid is then irradiated with light, the molecules make it acidic. In the dark, they return to the original state that makes the liquid more alkaline.
This is how the ETH researchers’ method works in detail: The researchers separate CO2 from the air by passing the air through a liquid containing photoacids in the dark. Since this liquid is alkaline, the CO2 reacts and forms carbonates. As soon as the salts in the liquid have accumulated to a significant degree, the researchers irradiate the liquid with light. This makes it acidic, and the carbonates transform to CO2. The CO2 bubbles out of the liquid, just as it does in a bottle of cola, and can be collected in gas tanks. When there is hardly any CO2 left in the liquid, the researchers switch off the light and the cycle starts all over again, with the liquid ready to capture CO2.
In practice, however, there was a problem: the photoacids used are unstable in water. “In the course of our earliest experiments, we realised that the molecules would decompose after one day,” says Anna de Vries, a doctoral student in Lukatskaya’s group and lead author of the study.
So Lukatskaya, de Vries and their colleagues analysed the decay of the molecule. They solved the problem by running their reaction not in water but in a mixture of water and an organic solvent. The scientists were able to determine the optimum ratio of the two liquids by laboratory experiments and were able to explain their findings thanks to model calculations carried out by researchers from the Sorbonne University in Paris.
For one thing, this mixture enabled them to keep the photoacid molecules stable in the solution for nearly a month. For another, it ensured that light could be used to switch the solution back and forth as required between being acidic and being alkaline. If the researchers were to use the organic solvent without water, the reaction would be irreversible.
Other carbon capture processes are cyclical as well. One established method works with filters that collect the CO2 molecules at ambient temperature. To subsequently remove the CO2 from the filters, these have to be heated to around 100 degrees Celsius. However, heating and cooling are energy-intensive: they account for the major share of the energy required by the filter method. “In contrast, our process doesn’t need any heating or cooling, so it requires much less energy,” Lukatskaya says. More than that, the ETH researchers’ new method potentially works with sunlight alone.
“Another interesting aspect of our system is that we can go from alkaline to acidic within seconds and back to alkaline within minutes. That lets us switch between carbon capture and release much more quickly than in a temperature-driven system,” de Vries explains.
With this study, the researchers have shown that photoacids can be used in the laboratory to capture CO2. Their next step on the way to market maturity will be to further increase the stability of the photoacid molecules. They also need to investigate the parameters of the entire process to optimise it further.
Optimization of Fuel Cell Electric Vehicle-to-Grid in Alberta by Mixed Integer Linear Programming
by Daniel Ding, Xiao-Yu Wu in IEEE 11th International Conference on Smart Energy Grid Engineering (SEGE)
University of Waterloo researchers are tapping into idled electric vehicles to act as mobile generators and help power overworked and aging electricity grids.
After analyzing energy demand on Alberta’s power grid during rush hour, the research proposes an innovative way to replenish electrical grids with power generated from fuel cells in trucks.
“Canada’s power grids need to be upgraded,” said Dr. XiaoYu Wu, lead researcher and a professor in Waterloo’s Department of Mechanical and Mechatronics Engineering. “But the price of Alberta’s power grid is much higher than other provinces. Most power is supplied by fossil fuels which results in high carbon emissions. The need to rapidly adjust generators to meet fluctuating demand is one of the reasons that the grid price is unstable and volatile. This creates the potential for clean energy storage to flatten the demand and price of electricity.”
The team’s research builds on vehicle-to-grid technology which employs special chargers to push unused energy from electric vehicle (EV) batteries back to the power grid for storage. This electricity in-storage can support the grid during weather-related outages or to reduce the demand during peak periods.
The research proposes paying drivers of fuel cell powered trucks to rest during rush hour and while resting, to plug into a hydrogen refueling station or pipeline and use their trucks’ idle fuel cells as generators to provide electricity to the grid. The result is less vehicle traffic on highways, reduced energy use at peak times and cleaner way to store energy.
Waterloo graduate student Daniel Ding developed a mathematical model to simulate the operation, then used software to analyze and model the feasibility and potential of hydrogen fuel cell-powered electric vehicles to balance the grid load and decrease the peak price and carbon intensity.
“Hydrogen fuel cells offer advantages over other fuels like batteries which require more investment and pollute more when you dispose of them,” Ding said. “Our preliminary findings show that using existing fuel cells in electric vehicles of the future can decrease costs on the grid.”
This energy storage solution has application beyond trucks. Heavy-duty vehicles and trains — like switcher locomotives that typically are idled until they’re needed to change train routes — could also be early adopters.
“With the increasing demand to decarbonize heavy duty vehicles, the fuel cell electric vehicle fleet is expected to expand rapidly,” said Wu. “Connecting these trucks to the grid for the peak-shifting purpose may provide economic incentives for adopting hydrogen fuel cell electric vehicles and help facilitate the emergence of a large-scale hydrogen economy.”
The researchers’ next steps plan to test these preliminary findings in the lab and the field to determine its real-world applicability.
Rigid- and soft-block-copolymerized conjugated polymers enable high-performance intrinsically stretchable organic solar cells
by Jin-Woo Lee, Heung-Goo Lee, Eun Sung Oh, Sun-Woo Lee, Tan Ngoc-Lan Phan, Sheng Li, Taek-Soo Kim, Bumjoon J. Kim in Joule
Professor Bumjoon Kim’s research team in the Department of Chemical and Biomolecular Engineering succeeded in implementing a stretchable organic solar cell by applying a newly developed polymer material that demonstrated the world’s highest photovoltaic conversion efficiency (19%) while functioning even when stretched for more than 40% of its original state. This new conductive polymer has high photovoltaic properties that can be stretched like rubber. The newly developed polymer is expected to play a role as a power source for next-generation wearable electronic devices.
With the market for wearable electric devices growing rapidly, stretchable solar cells that can function under strain have received considerable attention as an energy source. To build such solar cells, it is necessary that their photoactive layer, which converts light into electricity, shows high electrical performance while possessing mechanical elasticity. However, satisfying both of these two requirements is challenging, making stretchable solar cells difficult to develop.
On December 26, a KAIST research team from the Department of Chemical and Biomolecular Engineering (CBE) led by Professor Bumjoon Kim announced the development of a new conductive polymer material that achieved both high electrical performance and elasticity while introducing the world’s highest-performing stretchable organic solar cell.
Organic solar cells are devices whose photoactive layer, which is responsible for the conversion of light into electricity, is composed of organic materials. Compared to existing non-organic material-based solar cells, they are lighter and flexible, making them highly applicable for wearable electrical devices. Solar cells as an energy source are particularly important for building electrical devices, but high-efficiency solar cells often lack flexibility, and their application in wearable devices have therefore been limited to this point.
The team led by Professor Kim conjugated a highly stretchable polymer to an electrically conductive polymer with excellent electrical properties through chemical bonding, and developed a new conductive polymer with both electrical conductivity and mechanical stretchability. This polymer meets the highest reported level of photovoltaic conversion efficiency (19%) using organic solar cells, while also showing 10 times the stretchability of existing devices. The team thereby built the world’s highest performing stretchable solar cell that can be stretched up to 40% during operation, and demonstrated its applicability for wearable devices.
Professor Kim said, “Through this research, we not only developed the world’s best performing stretchable organic solar cell, but it is also significant that we developed a new polymer that can be applicable as a base material for various electronic devices that needs to be malleable and/or elastic.”
Subscribe to Paradigm!
Medium. Twitter. Telegram. Telegram Chat. Reddit. LinkedIn.
Main Sources
Research articles
