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At least 955 records · Page 53

Wind power costs driven by innovation and experience with further reductions on the horizon

The costs of wind power have declined to levels on par with or below those of conventional sources in many parts of the world. Wind power has become one of the fastest-growing sources of new electricity generation. We take stock of wind power cost evolution over the past 20 years, review methodologies commonly used for cost assessment, discuss the potential for continued cost reduction, and identify anticipated cost and value drivers. Our scope includes both onshore and offshore wind technologies. We draw from a vast body of literature on these topics to highlight key trends, approaches, and limitations. Furthermore, we discuss strategies for wind power assets to enhance their marginal economic value to the broader power system and consumers. We identify a myriad of factors that are expected to influence the future cost and value of wind power, including siting, project scale, turbine size, operational synergies, commodity prices, advancements in turbine technologies, enhanced management of the wind resource, and novel control technologies that provide value for the electricity grid. Because the common methods for forecasting future costs each have their own strengths and weaknesses, we find the best insights are elicited from a combination of methods. Overall, researchers and analysts anticipate further sizable cost reductions for onshore and offshore wind. Midrange forecasts for levelized cost of energy in 2050 are generally between $20 and $30/MWh for onshore wind and $40 and $60/MWh for offshore wind, a reduction to approximately half of today's levels. Optimistic forecasts anticipate these levels as early as 2030.

17 WIND ENERGY↗

Evaluating long-term emission impacts of large-scale electric vehicle deployment in the US using a human-Earth systems model

While large-scale adoption of electric vehicles (EVs) globally would reduce carbon dioxide (CO 2 ) and traditional air pollutant emissions from the transportation sector, emissions from the electric sector, refineries, and potentially other sources would change in response. Here, a multi-sector human-Earth systems model is used to evaluate the net long-term emission implications of large-scale EV adoption in the US over widely differing pathways of the evolution of the electric sector. Our results indicate that high EV adoption would decrease net CO 2 emissions through 2050, even for a scenario where all electric sector capacity additions through 2050 are fossil fuel technologies. Greater net CO 2 reductions would be realized for scenarios that emphasize renewables or decarbonization of electricity production. Net air pollutant emission changes in 2050 are relatively small compared to expected overall decreases from recent levels to 2050. States participating in the Regional Greenhouse Gas Initiative experience greater CO 2 and air pollutant reductions on a percentage basis. These results suggest that coordinated, multi-sector planning can greatly enhance the climate and environmental benefits of EVs. Additional factors are identified that influence the net emission impacts of EVs, including the retirement of coal capacity, refinery operations under reduced gasoline demands, and price-induced fuel switching in residential heating and in the industrial sector.

54 ENVIRONMENTAL SCIENCES↗

Flame Chemistry Workshop: a perspective on challenges and strategic actions in combustion experiments and chemical kinetics modeling

Continued progress in the development of predictive models for combustion chemistry—including ignition and flame behavior, species evolution, and combustion system performance—relies on overcoming enduring and emerging challenges in experimental measurements, theoretical formulations, and chemical kinetics mechanism construction. As combustion science continues to coincide with advances in sustainable fuels development, plasma technologies, and automated modeling capabilities, the need for coordinated, community-driven strategies is essential. The Flame Chemistry Workshop (FCWS), held biennially before the International Symposium on Combustion, serves as a dedicated platform to identify, consolidate, and address these challenges in a structured and collaborative manner. This perspective arises from discussions at the 7th FCWS in Milan, Italy (2024), and presents a collective view of the critical barriers currently limiting progress. Across the five technical domains discussed during the 7th FCWS – sustainable fuels combustion, advanced diagnostics for combustion measurements, experiments and modeling in plasma combustion, artificial intelligence and automated methods for theory and mechanisms generation, and chemical kinetic models—a series of persistent and emerging scientific challenges were identified, highlighting the need for deeper integration between three areas: theory, experiments, and modeling. In conclusion, the present article concisely describes present challenges that were identified in each of the technical domains in an effort to streamline and coordinate solutions to accelerate progress in combustion science.

Chemical kinetics↗

Bioconversion of renewable feedstocks by Rhodococcus opacus

The production of fuels and chemicals from renewable feedstocks is necessary for a fossil fuel independent economy. Lignin and other industrial wastes represent sustainable, non-food feedstocks that can be tapped for microbe-based bioproduction. Rhodococcus opacus is a gram-positive bacterium capable of catabolizing a broad range of feedstocks, and recent technological advances have further established its potential for lignin and industrial waste valorization. In the process of developing R. opacus as a platform for bioproduction, metabolic profiling has elucidated its native mechanisms of bioconversion, adaptive evolution has enhanced its tolerance towards inhibitory feedstocks, and genetic engineering has enabled it to produce novel products, such as wax esters, free fatty acids, and long chain hydrocarbons. Furthermore, we present recent examples of broad feedstock utilization and value-added chemical production by R. opacus , demonstrating its potential as an industrially-relevant strain.

09 BIOMASS FUELS↗

Challenges in the designing, planning and deployment of hydrogen refueling infrastructure for fuel cell electric vehicles

Hydrogen can power transportation with near zero greenhouse gas emissions. With government support, early market development is now underway in several nations thanks to technological advances in fuel cell vehicles and electricity generation from renewable energy. Deploying a sustainable hydrogen refueling infrastructure faces methodological and practical challenges ranging from the creation of appropriate codes to managing the co-evolution of the refueling network and growth of the stock of hydrogen fuel cell vehicles. Furthermore, this paper presents a comprehensive review of the challenges facing the designing, planning and deployment of hydrogen refueling infrastructure progress to date and outlook for the future. The design and costs of refueling infrastructure as well as the lifecycle environmental effects of hydrogen vehicles depend on how hydrogen is produced and delivered to refueling stations. In recent years, important advances have been made in methods for planning the numbers, sizes and location of hydrogen stations. Institutional barriers are also gradually being overcome. Co-evolving the deployment of stations and the demand for fuel cell vehicles remains a crucial subject for future research.

33 ADVANCED PROPULSION SYSTEMS↗

Challenges of nickel silicidation in CMOS technologies

In our paper, we review some of the key challenges associated with the Ni silicidation process in the most recent CMOS technologies. The introduction of new materials (e.g.SiGe), and of non-planar architectures bring some important changes that require fundamental investigation from a material engineering perspective. Following a discussion of the device architecture and silicide evolution through the last CMOS generations, we focus our study on a very peculiar defect, termed NiSi-Fangs. We describe a mechanism for the defect formation, and present a detailed material analysis that supports this mechanism. We highlight some of the possible metal enrichment processes of the nickel monosilicide such as oxidation or various RIE (Reactive Ion Etching) plasma process, leading to a metal source available for defect formation. Furthermore, we investigate the NiSi formation and re-formation silicidation differences between Si and SiGe materials, and between (1 0 0) and (1 1 1) orientations. Finally, we show that the thermal budgets post silicidation can lead to the formation of NiSi-Fangs if the structure and the processes are not optimized. Beyond the understanding of the defect and the discussion on the engineering solutions used to prevent its formation, the interest of this investigation also lies in the fundamental learning within the Ni–Pt–Si–Ge system and some additional perspective on Ni-based contacts to advanced microelectronic devices.

36 MATERIALS SCIENCE↗

Particle emission with identification from an atmospheric pressure plasma liquid interface

A conspicuous emission phenomenon of luminous particles from the liquid anode surface of an atmospheric pressure DC glow discharge is reported. The emission has been shown to occur when the plasma forms a pattern on the surface of the liquid electrolyte. Here, the spatial-temporal evolutions of the trajectories of emitted particles were studied using a high-speed imaging system. Particles were sampled in flight using a witness plate for analysis. Critical particle characteristics were examined using electron microscope technologies. The morphology of the resulting splats and compositions suggest that they are molten droplets with a great deal of structure, including evidence of nanoprecipitation. A theoretical model was employed to estimate the particle size from the measured splats, which provides a radius range within a hundred micrometers. This experiment leads to the postulation of a mechanism in which particle emission at the plasma liquid interface is likely driven by the Taylor cone effect.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

SN 2009js AT THE CROSSROADS BETWEEN NORMAL AND SUBLUMINOUS TYPE IIP SUPERNOVAE: OPTICAL AND MID-INFRARED EVOLUTION

We present a study of SN 2009js in NGC 918. Multi-band Kanata optical photometry covering the first {approx}120 days shows the source to be a Type IIP SN. Reddening is dominated by that due to our Galaxy. One-year-post-explosion photometry with the New Technology Telescope and a Subaru optical spectrum 16 days post-discovery both imply a good match with the well-studied subluminous SN 2005cs. The plateau-phase luminosity of SN 2009js and its plateau duration are more similar to the intermediate luminosity IIP SN 2008in. Thus, SN 2009js shares characteristics with both subluminous and intermediate luminosity supernovae (SNe). Its radioactive tail luminosity lies between SN 2005cs and SN 2008in, whereas its quasi-bolometric luminosity decline from peak to plateau (quantified by a newly defined parameter {Delta}logL, which measures adiabatic cooling following shock breakout) is much smaller than both the others'. We estimate the ejected mass of {sup 56}Ni to be low ({approx}0.007 M{sub Sun }). The SN explosion energy appears to have been small, similar to that of SN 2005cs. SN 2009js is the first subluminous SN IIP to be studied in the mid-infrared. It was serendipitously caught by Spitzer at very early times. In addition, it was detected by WISE 105 days later with a significant 4.6 {mu}m flux excess above the photosphere. The infrared excess luminosity relative to the photosphere is clearly smaller than that of SN 2004dj, which has been extensively studied in the mid-infrared. The excess may be tentatively assigned to heated dust with mass {approx}3 Multiplication-Sign 10{sup -5} M{sub Sun }, or to CO fundamental emission as a precursor to dust formation.

79 ASTRONOMY AND ASTROPHYSICS↗

Going to the Next Level: The Growth of Distributed Energy Resources [Guest Editorial]

The six articles in this special section focus on distributed energy resources (DERs). Since the first issue in this magazine on DER grid integration in the summer of 2009, DERs, specifically, solar PV-based systems, have evolved considerably to meet the needs of the power system from a planning and operations perspective. The result of this evolution is the theme of this issue: DERs play a major role in the power system. When relatively small numbers of PVs were first being installed, they were often showcases or demonstrations for the underlying technology, which was still quite expensive. The grid integration of these systems was a great research project, but many impacts we now see regularly simply did not exist at the earlier low-penetration levels. Now, nearly every distribution utility has experienced at least a few instances and challenges of DER integration within its service territory.

24 POWER TRANSMISSION AND DISTRIBUTION↗

SU-E-J-113: Effects of Deformable Registration On First-Order Texture Maps Calculated From Thoracic Lung CT Scans

Purpose: To determine the stability of eight first-order texture features following the deformable registration of serial computed tomography (CT) scans. Methods: CT scans at two different time points from 10 patients deemed to have no lung abnormalities by a radiologist were collected. Following lung segmentation using an in-house program, texture maps were calculated from 32×32-pixel regions of interest centered at every pixel in the lungs. The texture feature value of the ROI was assigned to the center pixel of the ROI in the corresponding location of the texture map. Pixels in the square ROI not contained within the segmented lung were not included in the calculation. To quantify the agreement between ROI texture features in corresponding pixels of the baseline and follow-up texture maps, the Fraunhofer MEVIS EMPIRE10 deformable registration algorithm was used to register the baseline and follow-up scans. Bland-Altman analysis was used to compare registered scan pairs by computing normalized bias (nBias), defined as the feature value change normalized to the mean feature value, and normalized range of agreement (nRoA), defined as the range spanned by the 95% limits of agreement normalized to the mean feature value. Results: Each patient’s scans contained between 6.8–15.4 million ROIs. All of the first-order features investigated were found to have an nBias value less than 0.04% and an nRoA less than 19%, indicating that the variability introduced by deformable registration was low. Conclusion: The eight first-order features investigated were found to be registration stable. Changes in CT texture maps could allow for temporal-spatial evaluation of the evolution of lung abnormalities relating to a variety of diseases on a patient-by-patient basis. SGA and HA receives royalties and licensing fees through the University of Chicago for computer-aided diagnosis technology. Research reported in this publication was supported by the National Institute Of General Medical Sciences of the National Institutes of Health under Award Number R25GM109439.

60 APPLIED LIFE SCIENCES↗

Modular assembly of transposable element arrays by microsatellite targeting in the guayule and rice genomes

Background: Guayule ( Parthenium argentatum A. Gray) is a rubber-producing desert shrub native to Mexico and the United States. Guayule represents an alternative to Hevea brasiliensis as a source for commercial natural rubber. The efficient application of modern molecular/genetic tools to guayule improvement requires characterization of its genome. Results: The 1.6 Gb guayule genome was sequenced, assembled and annotated. The final 1.5 Gb assembly, while fragmented (N50 = 22 kb), maps > 95% of the shotgun reads and is essentially complete. Approximately 40,000 transcribed, protein encoding genes were annotated on the assembly. Further characterization of this genome revealed 15 families of small, microsatellite-associated, transposable elements (TEs) with unexpected chromosomal distribution profiles. These SaTar (Satellite Targeted) elements, which are non-autonomous Mu-like elements (MULEs), were frequently observed in multimeric linear arrays of unrelated individual elements within which no individual element is interrupted by another. This uniformly non-nested TE multimer architecture has not been previously described in either eukaryotic or prokaryotic genomes. Five families of similarly distributed non-autonomous MULEs (microsatellite associated, modularly assembled) were characterized in the rice genome. Families of TEs with similar structures and distribution profiles were identified in sorghum and citrus. Conclusion: The sequencing and assembly of the guayule genome provides a foundation for application of current crop improvement technologies to this plant. In addition, characterization of this genome revealed SaTar elements with distribution profiles unique among TEs. Satar targeting appears based on an alternative MULE recombination mechanism with the potential to impact gene evolution.

59 BASIC BIOLOGICAL SCIENCES↗

Hydropower Vision A New Chapter for America's 1st Renewable Electricity Source

The U.S. Department of Energy’s (DOE’s) Wind and Water Power Technologies Office has led a first-of-its- kind comprehensive analysis to evaluate future pathways for low-carbon, renewable hydropower (hydropower generation and pumped storage) in the United States, focused on continued technical evolution, increased energy market value, and environmental sustainability. Undertaken through a broad-based collaborative effort, the Hydropower Vision initiative had four principal objectives: characterize the current state of hydropower in the United States, including trends, opportunities, and challenges; identify ways for hydropower to maintain and expand its contributions to the electricity and water management needs of the nation from the present through 2030 and 2050; examine critical environmental and social factors to assess how existing hydropower operations and potential new projects can minimize adverse effects, reduce carbon emissions from electricity generation, and contribute to stewardship of waterways and watersheds; and develop a roadmap identifying stakeholder actions that could support responsible ongoing operations and potential expansion of hydropower facilities. The Hydropower Vision analysis finds that U.S. hydropower could grow from 101 gigawatts (GW) of capacity to nearly 150 GW by 2050. Growth under this modeled scenario would result from a combination of 13 GW of new hydropower generation capacity (upgrades to existing plants, adding power at existing dams and canals, and limited development of new stream-reaches), and 36 GW of new pumped storage capacity. If this level of growth is achieved, benefits such as a savings of $209 billion from avoided greenhouse gas (GHG) emissions could be realized, of which $185 billion would be attributable to operation of the existing hydropower fleet. Transformative technical innovations able to meet the co-objectives of environmental sustainability and low-carbon energy will be critical to enabling additional hydropower growth beyond these levels. The Hydropower Vision report specifically does not evaluate or recommend new policy actions but instead analyzes the feasibility and certain benefits and costs of various credible scenarios, all of which could inform policy decisions at the federal, state, tribal, and local levels.

13 HYDRO ENERGY↗

Probing Attosecond Bound Electron Dynamics Driven by Strong-Field Light Transients

The project aimed to drive strong-field excitation of bound electronic coherences in gas-phase atoms and molecules using a novel source of near-single-cycle optical field transients, based on industrial-grade Yb:solid-state laser technology. Key objectives included generating near-single cycle field transients and isolated attosecond pulses, reconstructing time-dependent wave packets in atoms and molecules, probing their decoherence using attosecond interferometry, and controlling the dynamic evolution of systems on attosecond to few-femtosecond timescales. A secondary goal of the project was to develop field-resolved measurement platforms as a novel approach for studying electron dynamics in atomic and molecular systems.

74 ATOMIC AND MOLECULAR PHYSICS↗

Proceedings of Synthetic Biology: Engineering, Evolution and Design (SEED) Conference 2015

Synthetic Biology is an emerging discipline that seeks to accelerate the process of engineering biology. As such, the tools are broadly applicable to application areas, including chemicals and biofuels, materials, medicine and agriculture. A characteristic of the field is to look holistically at cellular design, from sensing and genetic circuitry to the manipulation of cellular processes and actuators, to controlling metabolism, to programming multicellular behaviors. Further, the types of cells that are manipulated are broad, from in vitro systems to microbes and fungi to mammalian and plant cells and living animals. Many of the projects in synthetic biology seek to move biochemical functions across organisms. The field is highly interdisciplinary with faculty and students spread across departments that focus on engineering (biological, chemical, electrical, mechanical, civil, computer science) and basic science (biology and systems biology, chemistry, physics). While there have been many one-off workshops and meeting on synthetic biology, the 2014 Synthetic Biology: Engineering, Evolution and Design (SEED) was the first of an annual conference series that serves as a reliable place to pull together the involved disciplines in order to organize and exchange advances in the science and technology in the field. Further, the SEED conferences have a strong focus on industry, with many companies represented and actively participating. A number of these companies have started major efforts in synthetic biology including large companies (e.g., Pfizer, Novartis, Dow, Dupont, BP, Total), smaller companies have recently gone public (e.g., Amyris, Gevo, Intrexon), and many start-ups (e.g., Teslagen, Refactored Materials, Pivot, Genomatica). There are a number of loosely affiliated Synthetic Biology Centers, including ones at MIT, Boston University, UCSD, UCSF, UC-Berkeley, Imperial College, Oxford, and ETH. SEED 2015 will serve as the primary meeting at which international synthetic biology centers and related infrastructure (synthesis/software/foundries) meet to discuss technology, standards, and education. SEED2015 will be the second in an annual series of meeting held to bring researchers from industry and academia in the area of Synthetic Biology. The first SEED conference was highly successful, attracting 285 attendees with varying backgrounds from academia, industry and government. The SEED series provides leadership in the development of the field of synthetic biology and serves to broaden the participants in the field by appealing to broad sectors in industry and providing a means for young investigators and those outside of the field to participate. Further, the series closely integrates with groups such as the SBCC to provide a means by which the synthetic biology community can communicate with policy makers. Further, we will pursue making the meeting the center for the exchange of educational materials as centers for synthetic biology emerge globally. Proceedings will be published each year in the journal ACS Synthetic Biology. After each SEED meeting, surveys are distributed to assess the success of the conference and to help guide changes year-to-year. The diverse application areas further extend the expertise needed from people in areas such as plant biology, agriculture and soil science, environmental science, medicine, and the chemical industry. These areas could have a widespread impact on society in a number of ways. For example, the CRISPR/Cas9 system that serves to immunize bacteria from phage has provided the fundamental chemistry that is used to edit the genomes of diverse organisms, including human stem cells, crop plants, and livestock animals.

09 BIOMASS FUELS↗

Metal Big Area Additive Manufacturing: Process Modeling and Validation

Metal Big Area Additive Manufacturing (mBAAM) is a new additive manufacturing (AM) technology for printing large-scale 3D objects. mBAAM is based on the gas metal arc welding process and uses a continuous feed of welding wire to manufacture an object. An electric arc forms between the wire and the substrate, which melts the wire and deposits a bead of molten metal along the predetermined path. In general, the welding process parameters and local conditions determine the shape of the deposited bead. The sequence of the bead deposition and the corresponding thermal history of the manufactured object determine the long range effects, such as thermal-induced distortions and residual stresses. Therefore, the resulting performance or final properties of the manufactured object are dependent on its geometry and the deposition path, in addition to depending on the basic welding process parameters. Physical testing is critical for gaining the necessary knowledge for quality prints, but traversing the process parameter space in order to develop an optimized build strategy for each new design is impractical by pure experimental means. Computational modeling and optimization may accelerate development of a build process strategy and saves time and resources. Because computational modeling provides these opportunities, we have developed a physics-based Finite Element Method (FEM) simulation framework and numerical models to support the mBAAM process s development and design. In this paper, we performed a sequentially coupled heat transfer and stress analysis for predicting the final deformation of a small rectangular structure printed using the mild steel welding wire. Using the new simulation technologies, material was progressively added into the FEM simulation as the arc weld traversed the build path. In the sequentially coupled heat transfer and stress analysis, the heat transfer was performed to calculate the temperature evolution, which was used in a stress analysis to evaluate the residual stresses and distortions. In this formulation, we assume that physics is directionally coupled, i.e. the effect of stress of the component on the temperatures is negligible. The experiment instrumentation (measurement types, sensor types, sensor locations, sensor placements, measurement intervals) and the measurements are presented. The temperatures and distortions from the simulations show good correlation with experimental measurements. Ongoing modeling work is also briefly discussed.

Additive Manufacturing↗

The Evolution of Artificial Intelligence

Artificial intelligence is playing a significant role in defining new research methods that bring us to resolution or discovery more quickly than ever before. Yet decades ago, computers mainly helped us with calculations, storing and editing information. Today, Argonne is using or developing many of these technologies as AI extends to new branches of science and technology, sprouting new buds that represent various facets of human function and cognition — from learning to language processing to visual recognition. Read the story here www.anl.gov/article/welcome-to-the-machine ENIAC footage provided by the Computer History Museum.

97 MATHEMATICS AND COMPUTING↗

Future of plasma etching for microelectronics: Challenges and opportunities

Plasma etching is an essential semiconductor manufacturing technology required to enable the current microelectronics industry. Along with lithographic patterning, thin-film formation methods, and others, plasma etching has dynamically evolved to meet the exponentially growing demands of the microelectronics industry that enables modern society. At this time, plasma etching faces a period of unprecedented changes owing to numerous factors, including aggressive transition to three-dimensional (3D) device architectures, process precision approaching atomic-scale critical dimensions, introduction of new materials, fundamental silicon device limits, and parallel evolution of post-CMOS approaches. The vast growth of the microelectronics industry has emphasized its role in addressing major societal challenges, including questions on the sustainability of the associated energy use, semiconductor manufacturing related emissions of greenhouse gases, and others. The goal of this article is to help both define the challenges for plasma etching and point out effective plasma etching technology options that may play essential roles in defining microelectronics manufacturing in the future. The challenges are accompanied by significant new opportunities, including integrating experiments with various computational approaches such as machine learning/artificial intelligence and progress in computational approaches, including the realization of digital twins of physical etch chambers through hybrid/coupled models. These prospects can enable innovative solutions to problems that were not available during the past 50 years of plasma etch development in the microelectronics industry. To elaborate on these perspectives, the present article brings together the views of various experts on the different topics that will shape plasma etching for microelectronics manufacturing of the future.

Engineering↗

Methyl Termination of p-Type Silicon Enables Selective Photoelectrochemical CO 2 Reduction by a Molecular Ruthenium Catalyst

Methyl-terminated p-type silicon photoelectrodes selectively drive CO 2 reduction by a homogeneous [Ru(tpy)(Mebim-py)(NCCH 3 )] 2+ catalyst (tpy = 2,2′:6′,2″-terpyridine, Mebim-py = 1-methylbenzimidazol-2-ylidene-3-(2′-pyridine)). A 460 mV photovoltage is quantified for the photoelectrode. Under 1 sun illumination, this system achieves a Faradaic efficiency of 87% for CO at −1.7 V vs Fc +/0 , matching reports of the same catalyst at metallic electrodes operating at −2.1 V. When 5% water is introduced, the CH 3 -terminated Si photoelectrode remains stable, selectivity for CO is retained, and current density increases. Methyl termination suppresses the competitive hydrogen evolution observed for H-terminated Si photoelectrodes, which under the same conditions produce ca. 60% CO and 8% H 2 and have unstable performance. Furthermore, these results establish that a semiconductor photoelectrode can power a molecular CO 2 reduction catalyst without hydrogen evolution by the photoelectrode itself. Methyl termination of p-Si allows CO 2 reduction to kinetically outcompete proton reduction, revealing an important design principle for selective fuel formation.

Catalysts↗