TL;DR
- Better solar power generation
- Organic solar device performance
- Perovskite solar cells: enhanced durability
- NREL advances method for recyclable wind turbine blades
- New theory could improve the design and operation of wind farms
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.
Latest Research
Solar irradiance variability around Asia Pacific: Spatial and temporal perspective for active use of solar energy
by Kalingga Titon Nur Ihsan, Hideaki Takenaka, Atsushi Higuchi, Anjar Dimara Sakti, Ketut Wikantika in Solar Energy
Amidst the ongoing energy crisis and under the threat of climate change, exploiting renewable energy sources has quickly become a global necessity. Though our options are varied, solar energy seems to be our best bet — experts estimate that it may become our main energy source well before the turn of the century.
Despite its clear advantages, solar energy generation has some limitations. Much like the wind, solar irradiance in a given region can vary quickly depending on weather conditions, causing fluctuations in power output. These fluctuations not only pose a problem for power grids but also imply that meeting energy demands may not always be a guarantee. Thus, having a clear understanding of the possible variations in solar irradiance in time and space is crucial to determining the optimal locations for solar power plants.
Against this backdrop, a research team led by Specially Appointed Assistant Professor Hideaki Takenaka from the Center for Environmental Remote Sensing, Chiba University, set out to extend our knowledge of solar irradiance over the Asia Pacific region. In their latest study, they conducted an in-depth analysis of solar irradiance data gathered from geostationary satellites. Other team members included Kalingga Titon Nur Ihsan, Graduate School of Science and Engineering, and Atsushi Higuchi, Center for Environmental Remote Sensing, both from Chiba University, as well as Anjar Dimara Sakti and Ketut Wikantika from the Center for Remote Sensing at Institut Teknologi Bandung.
The data for the analysis came from Himawari-8 and Himawari-9, two Japanese satellites that collect images with high temporal and spatial resolution over the Asia Pacific region. The researchers used AMATERASS solar radiation data obtained from quasi-real time analysis of solar radiation synchronized with geostationary satellite observation. They were developed by Dr. Takenaka and colleagues to accurately estimate solar irradiance via high-speed radiative transfer calculations using neural networks. AMATERASS operation started in July 2007, and analysis data was archived continuously for over 16 years. This data was made publicly available by the Chiba University, CEReS DAAC (Distributed Active Archive Center), downloaded 186,465,724 times, and used in various research and Japanese national projects. By leveraging this technology, the team estimated solar irradiance variability in terms of spatial and temporal heterogeneity. Simply put, they calculated how drastically solar radiation varies in space and time by analyzing solar irradiance data over a 20 km by 20 km grid every ten minutes.
Their analysis revealed interesting facts about solar irradiance over the region. For example, the team found that locations near the equator experienced lower fluctuations in solar irradiance over time compared to higher latitude regions due to the effects of rain and cloud activity. Moreover, regions of higher elevation exhibited higher heterogeneity due to higher cloud activity. The area around the Tibetan Plateau showed high seasonal changes in the magnitude of the ‘umbrella effect,’ which quantifies how much solar energy is reflected back to space.
“Our evaluations based on spatiotemporal data revealed characteristics that would’ve been impossible to achieve using a traditional approach that relies on simple long-term averages or TMY (Typical Meteorological Year) as a typical solar irradiance data,” highlights Dr. Takenaka.
In addition to these insights, the research team assessed the performance of over 1,900 existing solar power plants using annual and seasonal data. They found that, due to umbrella effects caused by clouds, the production of a large portion of these plants is not optimum from June to August. This implies that the most affected zones should not rely entirely on solar power to meet increased demands during these months.
Finally, the researchers also investigated the optimal format for future solar power plants, concluding that more widely distributed solar energy generation is superior to more localized efforts.
“Based on the spatial and temporal characteristics of solar irradiance, we suggest that it should be possible to suppress rapid fluctuations in solar power generation output by distributing small photovoltaic systems over a wide area rather than relying on large solar power plants,” explains Dr. Takenaka. “Worth noting, these conclusions come from weather and climate research, not an engineering perspective.” One way to achieve this vision might be through the use of rooftop solar panels, which is a growing trend in many countries.
Overall, the findings of this study will help us plan for the short- and long-term future of solar energy generation in the Asia Pacific region, bolstering sustainable energy technologies and aiding in our fight against climate change.
A Dibenzo[g,p]chrysene‐Based Organic Semiconductor with Small Exciton Binding Energy via Molecular Aggregation
by Hiroki Mori, Seihou JINNAI, Yasushi Hosoda, Azusa Muraoka, Ken-ichi Nakayama, Akinori Saeki, Yutaka Ie in Angewandte Chemie International Edition
Harnessing the power of the sun is vital for a clean, green future. To do so, we need optoelectronic devices, like solar cells, that can convert light into electricity efficiently. Now, a team led by Osaka University has discovered how to further improve device efficiency: by controlling how light-absorbing molecules stack together.
Organic optoelectronic devices, such as organic solar cells, are becoming increasingly sought after for their inherent advantages, e.g., flexibility or light weight. Their performance depends on how well their light-absorbing organic molecules convert light energy into ‘free-charge carriers’, which carry electric current. The energy needed to generate the free-charge carriers is referred to as ‘exciton-binding energy’.
The lower the exciton-binding energy, the easier it is to generate free-charge carriers, and thus the better the device performance. However, we still struggle to design molecules with low exciton-binding energy in a solid state.
Upon deeper inspection, the research team found that the exciton-binding energy of solid materials is affected by how their molecules stack together, which is referred to as aggregation.
“We synthesized two types of similar star-shaped molecules, one with a flexible center and the other with a rigid center,” explains lead author Hiroki Mori. “The individual molecules behaved similarly when they were dispersed in a solution, but quite differently when they were stacked together in thin solid films.”
The difference in behavior is due to the rigid molecules stacking together well, like plates, whereas the flexible molecules do not. In other words, when in a solid state, the rigid molecule has a much lower exciton-binding energy than the flexible molecule. To verify this, the team built a single-component organic solar cell and a photocatalyst using each molecule. The solar cell and photocatalyst made of the rigid molecule showed impressive performance because their low exciton-binding energy led to a high generation of free-charge carriers.
“Our findings, that making molecules that aggregate well can decrease the exciton-binding energy, are really exciting,” says senior author Yutaka Ie. “This could provide us with a new way to design more efficient optoelectronic devices.”
The team’s findings show that the interaction between molecules in a solid is important for device performance, and that the design of molecules for high-performance optoelectronic devices should look beyond individual molecular properties. This new way of decreasing exciton-binding energy could underpin the driving mechanisms and architecture of the next generation of optoelectronic devices.
Chiral-structured heterointerfaces enable durable perovskite solar cells
by Tianwei Duan, Shuai You, Min Chen, Wenjian Yu, Yanyan Li, Peijun Guo, Joseph J. Berry, Joseph M. Luther, Kai Zhu, Yuanyuan Zhou in Science
A research team led by the School of Engineering of the Hong Kong University of Science and Technology (HKUST) has constructed an unprecedented chiral-structured interface in perovskite solar cells, which enhances the reliability and power conversion efficiency of this fast-advancing solar technology and accelerates its commercialization.
A perovskite solar cell (PSC) is a type of solar cell that includes perovskite-structured compound materials, which are inexpensive to produce and simple to manufacture. Unlike conventional silicon solar cells that require expensive high-temperature, high-vacuum fabrication processes, perovskites can be easily made into thin films using various printing techniques at low cost. The performance of PSCs has climbed very rapidly in recent years, but there are still significant barriers to commercialization, particularly concerning their various stability aspects under real-world conditions. An outstanding challenge was the insufficient adhesion between the different layers of the cells, resulting in limited interfacial reliability.
To address this issue, Prof. ZHOU Yuanyuan, Associate Professor of the Department of Chemical and Biological Engineering (CBE) at HKUST, and his research team got inspiration from the mechanical strength of natural chiral materials and constructed an unprecedented chiral-structured interface in PSCs, unlocking very high reliability.
The team inserted chiral-structured interlayers based on R-/S-methylbenzyl-ammonium between the perovskite absorber and electron transport layer to create a strong, elastic heterointerface. The encapsulated solar cells retained 92% of their initial power conversion efficiencies after 200 cycles between −40°C and 85°C for 1,200 hours, tested under the International Electrotechnical Commission (IEC) 61215 solar cell standards.
“The intriguing mechanical properties of chiral materials are associated with the helical packing of their subunits, which resembles a mechanical spring,” said the first author of this work, Dr. DUAN Tianwei, currently a Research Assistant Professor in the CBE Department at HKUST and a previous Research Grants Council postdoctoral fellow. “Incorporating a chiral-structured interlayer at the crucial device interface makes the perovskite solar cell more mechanically durable and adaptable under various operational states,” she added.
“It is really the dawn for the commercialization of perovskite solar cells. Given the high efficiencies of these cells, if we could ultimately overcome the reliability issue, billions of energy markets will be seen,” said Prof. Zhou.
This breakthrough holds great promise for the future of solar energy. With the potential for enhanced reliability and power conversion efficiency, future perovskite solar panels could become even more dependable in various weather conditions, ensuring continuous electricity generation over extended periods.
Manufacture and testing of biomass-derivable thermosets for wind blade recycling
by Ryan W. Clarke, Erik G. Rognerud, Allen Puente-Urbina, David Barnes, Paul Murdy, Michael L. McGraw, Jimmy M. Newkirk, Ryan Beach, Jacob A. Wrubel, Levi J. Hamernik, Katherine A. Chism, Andrea L. Baer, Gregg T. Beckham, Robynne E. Murray, Nicholas A. Rorrer in Science
Researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) see a realistic path forward to the manufacture of bio-derivable wind blades that can be chemically recycled and the components reused, ending the practice of old blades winding up in landfills at the end of their useful life.
The findings are published in the new issue of the journal Science. The new resin, which is made of materials produced using bio-derivable resources, performs on par with the current industry standard of blades made from a thermoset resin and outperforms certain thermoplastic resins intended to be recyclable.
The researchers built a prototype 9-meter blade to demonstrate the manufacturability of an NREL-developed biomass-derivable resin nicknamed PECAN. The acronym stands for PolyEster Covalently Adaptable Network, and the manufacturing process dovetails with current methods. Under existing technology, wind blades last about 20 years, and afterward they can be mechanically recycled such as shredded for use as concrete filler. PECAN marks a leap forward because of the ability to recycle the blades using mild chemical processes.
The chemical recycling process allows the components of the blades to be recaptured and reused again and again, allowing the remanufacture of the same product, according to Ryan Clarke, a postdoctoral researcher at NREL and first author of the new paper. “It is truly a limitless approach if it’s done right.” He said the chemical process was able to completely break down the prototype blade in six hours.
The paper involved work from investigators at five NREL research hubs, including the National Wind Technology Center and the BOTTLE Consortium. The researchers demonstrated an end-of-life strategy for the PECAN blades and proposed recovery and reuse strategies for each component.
“The PECAN method for developing recyclable wind turbine blades is a critically important step in our efforts to foster a circular economy for energy materials,” said Johney Green, NREL’s associate laboratory director for Mechanical and Thermal Engineering Sciences.
The research into the PECAN resin began with the end. The scientists wanted to make a wind blade that could be recyclable and began experimenting with what feedstock they could use to achieve that goal. The resin they developed using bio-derivable sugars provided a counterpoint to the conventional notion that a blade designed to be recyclable will not perform as well.
“Just because something is bio-derivable or recyclable does not mean it’s going to be worse,” said Nic Rorrer, one of the two corresponding authors of the paper. He said one concern others have had about these types of materials is that the blade would be subject to greater “creep,” which is when the blade loses its shape and deforms over time. “It really challenges this evolving notion in the field of polymer science, that you can’t use recyclable materials because they will underperform or creep too much.”
Composites made from the PECAN resin held their shape, withstood accelerated weatherization validation, and could be made within a timeframe similar to the existing cure cycle for how wind turbine blades are currently manufactured. While wind blades can measure the length of a football field, the size of the prototype provided proof of the process.
“Nine meters is a scale that we were able to demonstrate all of the same manufacturing processes that would be used at the 60-, 80-, 100-meter blade scale,” said Robynne Murray, the second corresponding author.
Unified momentum model for rotor aerodynamics across operating regimes
by Liew, J., Heck, K.S. & Howland, M.F. in Nature Communications
The blades of propellers and wind turbines are designed based on aerodynamics principles that were first described mathematically more than a century ago. But engineers have long realized that these formulas don’t work in every situation. To compensate, they have added ad hoc “correction factors” based on empirical observations.
Now, for the first time, engineers at MIT have developed a comprehensive, physics-based model that accurately represents the airflow around rotors even under extreme conditions, such as when the blades are operating at high forces and speeds, or are angled in certain directions. The model could improve the way rotors themselves are designed, but also the way wind farms are laid out and operated. The new findings in an open-access paper by MIT postdoc Jaime Liew, doctoral student Kirby Heck, and Michael Howland, the Esther and Harold E. Edgerton Assistant Professor of Civil and Environmental Engineering.
“We’ve developed a new theory for the aerodynamics of rotors,” Howland says. This theory can be used to determine the forces, flow velocities, and power of a rotor, whether that rotor is extracting energy from the airflow, as in a wind turbine, or applying energy to the flow, as in a ship or airplane propeller. “The theory works in both directions,” he says.
Because the new understanding is a fundamental mathematical model, some of its implications could potentially be applied right away. For example, operators of wind farms must constantly adjust a variety of parameters, including the orientation of each turbine as well as its rotation speed and the angle of its blades, in order to maximize power output while maintaining safety margins. The new model can provide a simple, speedy way of optimizing those factors in real time.
“This is what we’re so excited about, is that it has immediate and direct potential for impact across the value chain of wind power,” Howland says.
Known as momentum theory, the previous model of how rotors interact with their fluid environment — air, water, or otherwise — was initially developed late in the 19th century. With this theory, engineers can start with a given rotor design and configuration, and determine the maximum amount of power that can be derived from that rotor — or, conversely, if it’s a propeller, how much power is needed to generate a given amount of propulsive force.
Momentum theory equations “are the first thing you would read about in a wind energy textbook, and are the first thing that I talk about in my classes when I teach about wind power,” Howland says. From that theory, physicist Albert Betz calculated in 1920 the maximum amount of energy that could theoretically be extracted from wind. Known as the Betz limit, this amount is 59.3 percent of the kinetic energy of the incoming wind.
But just a few years later, others found that the momentum theory broke down “in a pretty dramatic way” at higher forces that correspond to faster blade rotation speeds or different blade angles, Howland says. It fails to predict not only the amount, but even the direction of changes in thrust force at higher rotation speeds or different blade angles: Whereas the theory said the force should start going down above a certain rotation speed or blade angle, experiments show the opposite — that the force continues to increase. “So, it’s not just quantitatively wrong, it’s qualitatively wrong,” Howland says.
The theory also breaks down when there is any misalignment between the rotor and the airflow, which Howland says is “ubiquitous” on wind farms, where turbines are constantly adjusting to changes in wind directions. In fact, in an earlier paper in 2022, Howland and his team found that deliberately misaligning some turbines slightly relative to the incoming airflow within a wind farm significantly improves the overall power output of the wind farm by reducing wake disturbances to the downstream turbines.
In the past, when designing the profile of rotor blades, the layout of wind turbines in a farm, or the day-to-day operation of wind turbines, engineers have relied on ad hoc adjustments added to the original mathematical formulas, based on some wind tunnel tests and experience with operating wind farms, but with no theoretical underpinnings.
Instead, to arrive at the new model, the team analyzed the interaction of airflow and turbines using detailed computational modeling of the aerodynamics. They found that, for example, the original model had assumed that a drop in air pressure immediately behind the rotor would rapidly return to normal ambient pressure just a short way downstream. But it turns out, Howland says, that as the thrust force keeps increasing, “that assumption is increasingly inaccurate.”
And the inaccuracy occurs very close to the point of the Betz limit that theoretically predicts the maximum performance of a turbine — and therefore is just the desired operating regime for the turbines. “So, we have Betz’s prediction of where we should operate turbines, and within 10 percent of that operational set point that we think maximizes power, the theory completely deteriorates and doesn’t work,” Howland says.
Through their modeling, the researchers also found a way to compensate for the original formula’s reliance on a one-dimensional modeling that assumed the rotor was always precisely aligned with the airflow. To do so, they used fundamental equations that were developed to predict the lift of three-dimensional wings for aerospace applications.
The researchers derived their new model, which they call a unified momentum model, based on theoretical analysis, and then validated it using computational fluid dynamics modeling. In follow up work not yet published, they are doing further validation using wind tunnel and field tests.
One interesting outcome of the new formula is that it changes the calculation of the Betz limit, showing that it’s possible to extract a bit more power than the original formula predicted. Although it’s not a significant change — on the order of a few percent — “it’s interesting that now we have a new theory, and the Betz limit that’s been the rule of thumb for a hundred years is actually modified because of the new theory,” Howland says. “And that’s immediately useful.” The new model shows how to maximize power from turbines that are misaligned with the airflow, which the Betz limit cannot account for.
The aspects related to controlling both individual turbines and arrays of turbines can be implemented without requiring any modifications to existing hardware in place within wind farms. In fact, this has already happened, based on earlier work from Howland and his collaborators two years ago that dealt with the wake interactions between turbines in a wind farm, and was based on the existing, empirically based formulas.
“This breakthrough is a natural extension of our previous work on optimizing utility-scale wind farms,” he says, because in doing that analysis, they saw the shortcomings of the existing methods for analyzing the forces at work and predicting power produced by wind turbines. “Existing modeling using empiricism just wasn’t getting the job done,” he says.
In a wind farm, individual turbines will sap some of the energy available to neighboring turbines, because of wake effects. Accurate wake modeling is important both for designing the layout of turbines in a wind farm, and also for the operation of that farm, determining moment to moment how to set the angles and speeds of each turbine in the array.
Until now, Howland says, even the operators of wind farms, the manufacturers, and the designers of the turbine blades had no way to predict how much the power output of a turbine would be affected by a given change such as its angle to the wind without using empirical corrections. “That’s because there was no theory for it. So, that’s what we worked on here. Our theory can directly tell you, without any empirical corrections, for the first time, how you should actually operate a wind turbine to maximize its power,” he says.
Because the fluid flow regimes are similar, the model also applies to propellers, whether for aircraft or ships, and also for hydrokinetic turbines such as tidal or river turbines. Although they didn’t focus on that aspect in this research, “it’s in the theoretical modeling naturally,” he says.
The new theory exists in the form of a set of mathematical formulas that a user could incorporate in their own software, or as an open-source software package that can be freely downloaded from GitHub.
“It’s an engineering model developed for fast-running tools for rapid prototyping and control and optimization,” Howland says. “The goal of our modeling is to position the field of wind energy research to move more aggressively in the development of the wind capacity and reliability necessary to respond to climate change.”
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