Insights on platinum-carbon catalyst degradation mechanism for oxygen reduction reaction in acidic and alkaline media
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Labata, Marc Francis (ORCID:0000000248234792)↗
SEARCH · Engineering Papers
Results for “carbon reduction”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Electrochemical trends of a hybrid platinum and metal–nitrogen–carbon catalyst library for the oxygen reduction reaction
Pt nanoparticles supported on a library of 3d, 4d, 5d and f metal M–N–C catalysts for the ORR.
Ly, Alvin↗
Special Issue of IJGGC: Nexus of Water and Carbon Capture and Storage
The mission of the Regional Carbon Sequestration Partnership (RCSP) Water Working Group (WWG) is to address stakeholder concerns regarding emerging carbon capture and storage (CCS) technology and potential interactions with local and regional water resources. As part of that mission, the WWG has been working with the International Journal of Greenhouse Gas Control (IJGGC) to develop a Special Issue dedicated to the nexus of water and CCS. Research papers were solicited, edited, and subsequently published in IJGGC. These articles were then submitted to IJGGC on December, 29, 2016, to be published online in a virtual special issue. The articles published in the virtual special issue build upon the research that has been published in IJGGC over the previous 4 years to complete a more comprehensive understanding of water issues associated with CCS.
54 ENVIRONMENTAL SCIENCES↗
High Tortuosity Carbon Dioxide Conversion Device for CO2 Reduction into Useful Products for Life Support Systems
Chemical reduction of CO2 is a needed function for Life Support during long term space travel. Such processes can create useful products such as oxygen, hydrocarbon fuels, and polymer feedstocks.
Chen, Bin↗
Revealing the Structure of Single Cobalt Sites in Carbon Nitride for Photocatalytic CO 2 Reduction
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99 GENERAL AND MISCELLANEOUS↗
Port Authority of New York and New Jersey Sustainable Aviation Fuel Logistics and Production Study
The Port Authority of New York and New Jersey (PANYNJ) sustainability commitment is to meet the goals set by the Paris Agreement, with an interim greenhouse gas reduction target of 35% by 2025 and 80% by 2050. PANYNJ is seeking sustainable solutions to reduce carbon emissions for all public forms of transportation, including aviation. Similarly, the global aviation industry adopted the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA), which seeks to cap net carbon dioxide (CO 2 ) aviation emissions at 2020 levels through 2035. Industry has also set a goal of reducing CO 2 emissions by 50% compared to 2005 levels by 2050. Sustainable aviation fuel (SAF), made from non-petroleum feedstocks, is a near-term alternative fuel that reduces emissions from air transportation. The National Renewable Energy Laboratory (NREL) conducted a resource assessment and a techno-economic analysis to identify the potential for production in the port district. Although SAF could be sourced from other areas of the United States or imported, an evaluation of local production was conducted due to the potential positive impacts of a circular economy by converting local waste feedstocks into SAF for use at nearby airports. The study found that the highest volumes of feedstock nearby were municipal solid waste and woody biomass. SAF must be blended with Jet A up to certain percent determined by ASTM International fuel quality standards prior to use in aircraft. SAF from a stand-alone facility could be delivered by barge, rail, or truck to a Linden, New Jersey based terminal for blending with Jet A or it could be blended in the Gulf region and shipped via the Colonial pipeline to one of the terminals. The investment will take place at the terminal(s) to accommodate SAF/Jet A blends and it will be business as usual for the airports in how they receive fuel and distribute it to aircraft.
09 BIOMASS FUELS↗
Advanced air revitalization system modeling and testing
To support manned lunar and Martian exploration, an extensive evaluation of air revitalization subsystems (ARS) is being conducted. The major operations under study include carbon dioxide removal and reduction; oxygen and nitrogen production, storage, and distribution; humidity and temperature control; and trace contaminant control. A comprehensive analysis program based on a generalized block flow model was developed to facilitate the evaluation of various processes and their interaction. ASPEN PLUS was used in modelling carbon dioxide removal and reduction. Several life support test stands were developed to test new and existing technologies for their potential applicability in space. The goal was to identify processes which use compact, lightweight equipment and maximize the recovery of oxygen and water. The carbon dioxide removal test stands include solid amine/vacuum desorption (SAVD), regenerative silver oxide chemisorption, and electrochemical carbon dioxide concentration (EDC). Membrane-based carbon dioxide removal and humidity control, catalytic reduction of carbon dioxide, and catalytic oxidation of trace contaminants were also investigated.
Dall-Baumann, Liese↗
Ecosystem Carbon Emissions from 2015 Forest Fires in Interior Alaska
In the summer of 2015, hundreds of wildfires burned across the state of Alaska, and consumed more than 1.6 million ha of boreal forest and wetlands in the Yukon-Koyukuk region. Mapping of 113 large wildfires using Landsat satellite images from before and after 2015 indicated that nearly 60% of this area was burned at moderate-to-high severity levels. Field measurements near the town of Tanana on the Yukon River were carried out in July of 2017 in both unburned and 2015 burned forested areas (nearly adjacent to one-another) to visually verify locations of different Landsat burn severity classes (low, moderate, or high). Results: Field measurements indicated that the loss of surface organic layers in boreal ecosystem fires is a major factor determining post-fire soil temperature changes, depth of thawing, and carbon losses from the mineral topsoil layer. Measurements in forest sites showed that soil temperature profiles to 30 cm depth at burned forest sites increased by an average of 8o - 10o C compared to unburned forest sites. Sampling and laboratory analysis indicated a 65% reduction in soil carbon content and a 58% reduction in soil nitrogen content in severely burned sample sites compared to soil mineral samples from nearby unburned spruce forests. Conclusions: Combined with nearly unprecedented forest areas severely burned in the Interior region of Alaska in 2015, total ecosystem fire emission of carbon to the atmosphere exceeded most previous estimates for the state.
Ecosystem↗
Review of Carbon Support Coordination Environments for Single Metal Atom Electrocatalysts (SACS)
This topical review focuses on the distinct role of carbon support coordination environment of single-atom catalysts (SACs) for electrocatalysis. The article begins with an overview of atomic coordination configurations in SACs, including a discussion of the advanced characterization techniques and simulation used for understanding the active sites. A summary of key electrocatalysis applications is then provided. These processes are oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), nitrogen reduction reaction (NRR), and carbon dioxide reduction reaction (CO 2 RR). The review then shifts to modulation of the metal atom-carbon coordination environments, focusing on nitrogen and other non-metal coordination through modulation at the first coordination shell and modulation in the second and higher coordination shells. Representative case studies are provided, starting with the classic four-nitrogen-coordinated single metal atom (M$-$N 4 ) based SACs. Bimetallic coordination models including homo-paired and hetero-paired active sites are also discussed, being categorized as emerging approaches. The theme of the discussions is the correlation between synthesis methods for selective doping, the carbon structure–electron configuration changes associated with the doping, the analytical techniques used to ascertain these changes, and the resultant electrocatalysis performance. In conclusion, critical unanswered questions as well as promising underexplored research directions are identified.
36 MATERIALS SCIENCE↗
Building Stock Models for Embodied Carbon Emissions—A Review of a Nascent Field
Building stock modeling emerges as a critical tool in the strategic reduction of embodied carbon emissions, which is pivotal in reshaping the evolving construction sector. This review provides an overall view of modern methodologies in building stock modeling, homing in on the nuances of embodied carbon analysis in construction. Examining 23 seminal papers, our study delineates two primary modeling paradigms—top-down and bottom-up—each further compartmentalized into five innovative methods. This study points out the challenges of data scarcity and computational demands, advocating for methodological advancements that promise to refine the precision of building stock models. A groundbreaking trend in recent research is the incorporation of machine learning algorithms, which have demonstrated remarkable capacity, improving stock classification accuracy by 25% and urban material quantification by 40%. Furthermore, the application of remote sensing has revolutionized data acquisition, enhancing data richness by a factor of five. This review offers a critical examination of current practices and charts a course toward an environmentally prudent future. It underscores the transformative impact of building stock modeling in driving ecological stewardship in the construction industry, positioning it as a cornerstone in the quest for sustainability and its significant contribution toward the grand vision of an eco-efficient built environment.
Hu, Ming (ORCID:0000000325831161)↗
The effects of rising CO 2 concentrations on terrestrial systems: scaling it up
Since the Industrial Revolution, atmospheric CO 2 concentrations have increased by c. 50%, from 280 ppm to a current level of 415 ppm and rising (Ciais et al., 2013). But CO 2 concentrations would be even higher if the terrestrial biosphere was not acting as a carbon sink, absorbing c. 30% of the CO 2 we emit every year (Le Quéré et al., 2016). Understanding how increasing CO 2 concentrations will alter the ability of vegetation and soils to sequester carbon is therefore critical for predicting the trajectory of future climate change, since a reduction in this carbon sink would cause a more rapid accumulation of CO2 in the atmosphere (Dusenge et al., 2019). In this issue of New Phytologist, Walker et al. (2021; pp. 2413–2445) synthesize data from an incredibly broad range of sources, including herbaria, free air CO 2 enrichment (FACE) studies, ice cores, eddy covariance sites, and remote sensing, and examine an enormous diversity of measurements (such as soil respiration rates, glucose isotopomers from leaves, tree ring width data, stream-gauges for runoff, and direct atmospheric CO 2 measurements) to address the question of how increasing CO2 concentrations are affecting the carbon uptake capacity of our planet.
54 ENVIRONMENTAL SCIENCES↗
Failure Analysis–Informed Risk Assessment Framework for Geological Carbon Storage Using Numerical Simulation and Machine Learning
Geological carbon storage (GCS) is recognized as a critical technology for achieving large-scale reductions in anthropogenic carbon dioxide (CO 2 ) emissions. Ensuring long-term containment and safety requires robust risk assessment frameworks that account for geological uncertainty and identify potential failure scenarios. Among various indicators, the area of review (AoR) serves as a key metric for evaluating storage performance, regulatory compliance, and monitoring design, as it delineates the spatial extent impacted by pressure buildup and plume migration. However, conventional AoR-based risk assessments typically perturb parameters within narrow uncertainty bounds, potentially overlooking rare but high-impact events arising from extreme geological conditions. In this study, we present a failure analysis–informed risk assessment framework for large-scale GCS projects to improve site prescreening and monitoring design. A suite of 300 numerical simulations was generated using stochastic geological models that vary five key parameters: net-to-gross ratio, anisotropy azimuth, porosity multiplier, permeability multiplier, and vertical-to-horizontal permeability ratio. Among these, 200 realizations represent normal geological uncertainty, while 100 additional cases explore extreme yet plausible conditions for failure-case analysis. The AoR was simulated and computed from pressure and CO 2 saturation fields, where the baseline AoR boundary, representing the extent predicted under typical geological uncertainty, was defined as the union of 200 normal-range simulations, and failure was identified when extreme-range cases exceeded this baseline. Results show that incorporating broader parameter uncertainty produces significantly larger AoR extents, underscoring the potential underestimation of risk under conventional uncertainty ranges. Furthermore, spatial probability maps derived from failure-induced AoR exceedance identify regions requiring enhanced monitoring attention. Various machine learning (ML)–based classifiers were developed to predict failure occurrence from geological parameters, with the random forest model achieving the highest performance (F1-score of 0.986). Consistent findings from correlation coefficient, feature importance, and Sobol sensitivity analyses reveal that low net-to-gross ratios and permeability multipliers are the dominant risk drivers, reflecting reduced reservoir connectivity and limited pressure dissipation. Altogether, these results provide a novel framework for risk-informed site prescreening and monitoring design that explicitly considers rare but high-impact geological scenarios in GCS projects.
25 ENERGY STORAGE↗
CORSIA: The first internationally adopted approach to calculate life-cycle GHG emissions for aviation fuels
The aviation sector has grown at a significant pace in recent years, and despite improvements in aircraft efficiency, the sector's impact on climate change is a growing concern. To address this concern, the International Civil Aviation Organization (ICAO) established the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) to help reduce aviation greenhouse gas (GHG) emissions. This paper presents a methodology agreed by the 193 ICAO member states to evaluate the life-cycle GHG emissions of sustainable aviation fuels (SAFs), in the CORSIA system. The core life-cycle assessment and induced land use change values of SAFs are presented to determine the GHG savings of certified pathways. The paper aims to present that a number of SAFs can yield significant life-cycle emission reductions compared to petroleum-derived jet fuel. This implies the potentially major role of SAFs in reducing aviation's carbon footprint.
54 ENVIRONMENTAL SCIENCES↗
Redox Energy and Sulfur Chemistry in Prebiotic Polymer Synthesis and Replication
In the past year we have made significant progress in three research areas: (1) Most importantly, we discovered a new pathway of prebiotic amino acid synthesis in which formaldehyde and glycolaldehyde (substrates of the formose reaction) react with ammonia yielding alanine and homoserine in the presence of thiol catalysts. This thiol-dependent synthesis of amino acids undoubtedly occurs via amino acid thioester intermediates capable of forming peptides. This 'one-pot' reaction system operates under mild aqueous conditions, and like modern amino acid biosynthesis, uses sugar intermediates which are converted to amino acids by energy-yielding redox disproportionation. (2) Finally, in preparation for the analysis of Martian meteorite samples, we upgraded our HPLC system and developed an improved method capable of detecting a I femtomole of amino acid enantiomers. (3) We completed our analysis of the energetics of metabolism that revealed that life depends on biosynthetic processes driven by chemical energy made available by the redox disproportionation of carbon groups of sugars. We established that the favorable energy of redox disproportionation is based on the universal reduction potentials of carbon groups. We concluded that it is hard to imagine any other organic molecule besides sugars (formaldehyde oligomers) having the energy and reactivity needed to drive either modem biosynthesis or the chemical processes behind its origin.
Weber, Arthur L.↗
Copper carbon composite wire with a uniform carbon dispersion made by friction extrusion
Copper-carbon composites are a group of materials with excellent mechanical, electrical, thermal, and tribological properties. However, bulk size copper-carbon composites made by the traditional manufacturing processes, like rolling or extrusion, fall short of reaching some of these properties predicted by theory or demonstrated only by samples at centimeter scale or smaller. The two main challenges to the successful scaling-up are: 1) to uniformly disperse carbon in the metal matrix; 2) to avoid degradation due to oxidation or reaction from overheating. In this work, we first demonstrate friction extrusion as a new method to make bulk-size void-free copper-carbon composite wires with homogenized carbon dispersion. Three different carbon varieties, graphite powder, graphene nanopowder, and carbon nanotubes, were added to the copper matrix with the concentration ranging from 0.5 wt% to 15 wt%. Special tooling, processing parameters, and procedures were developed, especially for high carbon content samples. Ten-fold reductions of both copper grain size and carbon particle size were achieved and attributed to the high shear deformation. Energy dispersive X-ray spectrometry indicates the carbon powder was refined to a sub-micron level and uniformly dispersed in the copper matrix. Compared with that of pure copper, the thermal capacity of the composite wire increases by 30 % while density reduces by 29 %.
Friction extrusion, Metal matrix composite, Graphe↗
Comparison of Silicon Decarbonization Methods to Reduce Process Emissions and Energy Consumption
The demand for silicon is rising due to its use in solar cells, electronics, and alloying as part of the green transition. However, these products require silicon metal (metallurgical grade silicon, >98% Si) as their main raw material before undergoing further chemical refining, usually via gas phase in methods such as the Siemens process. Silicon metal is currently produced in a submerged arc furnace via carbothermic reduction of quartz, which results in 10-12 tCO2/tSi. More than 40% of these emissions are process emissions, meaning they do not include contributions from electricity generation or transport. This talk will discuss promising methods to reduce or eliminate these process emissions. These include the use of biocarbon and carbon capture, aluminothermic reduction, electrochemical reduction with molten salts, and use of hydrogen in a modified Siemens process. Biocarbon and carbon capture is a straightforward method to reduce the net carbon emissions of the process, but long-term sustainable production of high-quality charcoal is a challenge. Aluminothermic reduction makes good use of aluminum byproducts such as dross but is perhaps limited in its applications to aluminum-silicon alloy products. Electrochemical reduction is promising as a method of producing high purity Si from quartz, without further need for the Siemens process, but is still in early stages of research and slow processing times are a concern. Finally, the use of hydrogen in a modified Siemens process would also result in a high purity Si product from quartz, however the process has considerable logistical challenges with corrosive and unstable gases at high temperatures. This talk will further expand on the potential merits and challenges of each method, while comparing their potential to reduce emissions and/or energy consumption while meeting global demand.
decarbonization↗
Series Bosch System Development
State-of-the-art (SOA) carbon dioxide (CO2) reduction technology for the International Space Station produces methane as a byproduct. This methane is subsequently vented overboard. The associated loss of hydrogen ultimately reduces the mass of oxygen that can be recovered from CO2 in a closed-loop life support system. As an alternative to SOA CO2 reduction technology, NASA is exploring a Series-Bosch system capable of reducing CO2 with hydrogen to form water and solid carbon. This results in 100% theoretical recovery of oxygen from metabolic CO2. In the past, Bosch-based technology did not trade favorably against SOA technology due to a high power demand, low reaction efficiencies, concerns with carbon containment, and large resupply requirements necessary to replace expended catalyst cartridges. An alternative approach to Bosch technology, labeled "Series-Bosch," employs a new system design with optimized multi-stage reactors and a membrane-based separation and recycle capability. Multi-physics modeling of the first stage reactor, along with chemical process modeling of the integrated system, has resulted in a design with potential to trade significantly better than previous Bosch technology. The modeling process and resulting system architecture selection are discussed.
Abney, Morgan B.↗
Integration of Omics into a New Comprehensive Rate Law for Competitive Terminal Electron-Accepting Processes in Reactive Transport Models: Application to N, Fe, S, and Contaminant Transformations in Stream and Wetland Sediments
Surface waters represent important sources of alternate energy and drinking water in the United States, and characterizing the biogeochemical processes that affect surface water quality is relevant to the DOE-BER mission. Sediment biogeochemical processes regulate the release of carbon (C), nutrients, and contaminants to surface waters and thus influence water quality. Sediment biogeochemical processes are dynamic and affected by the deposition and remobilization of solid material and changes in environmental conditions driven by water discharge variations. Wetlands are important natural filters of surface waters which may either trap, metabolize, or mobilize nutrients and contaminants. Despite their importance, biogeochemical processes regulating nutrient and contaminant release and C transformation in stream and wetland sediments cannot be predicted accurately by current mathematical models. These reactive transport models largely rely on detectable changes in geochemical conditions to activate metabolic processes, do not accurately account for the competition between microbial processes, and poorly constrain effects of hydrological perturbations on biogeochemical processes. In this BER-SBR exploratory project, metagenomic and geochemical signatures were combined to identify microbially-mediated redox processes in anaerobic stream and wetland sediments from the Savannah River Site (SRS, ANL SFA) and East Fork Poplar Creek (EFPC, ORNL SFA) that play important roles in C, uranium (U), and mercury (Hg) transformations. In addition, sediment incubations were conducted to examine the competition between anaerobic respiration processes Finally, new rate laws were developed for reactive transport models that rely on complementary metagenomic and geochemical signatures to identify the underlying anaerobic microbial processes in stream and wetland sediments, describe the competition between the dominant metabolic processes involved in nutrient release and U and Hg mobilization, and more accurately quantify carbon transformation and the response of microbial processes to changes in redox conditions associated with hydrological forcing. These rate laws were optimized in batch reactors with SRS wetland sediments, where iron and sulfate reduction dominate. Anaerobic carbon remineralization processes followed the expected thermodynamic sequence of microbial respiration with depth in both sediments, except that geochemical signals indicated that sulfate reduction was inactive in EFPC sediments and moderate in SRS wetland sediments. Estimates indicated that microbial iron reduction contributed to at least half of the production of reduced iron in these sediments. Incubations demonstrated that nitrate reduction, denitrification, and dissimilatory nitrate reduction to ammonium were active in the natural EFPC sediment and activated upon nitrate amendment in these nitrate-rich sediments. In turn, these processes were outcompeted by the addition of either iron oxides or sulfate as alternative terminal electron acceptors. Although geochemical products of sulfate reduction were not detected in the incubations, the abundance of sulfate reduction genes increased with depth in the sediment and was equally more pronounced in treatments amended with either iron oxides or sulfate. Simultaneously, anaerobic sulfide oxidizing bacteria coupling sulfide oxidation to DNRA (and not conventional denitrification) were apparently enriched over time, regardless of the treatments. These findings indicate that sulfate reduction is important in freshwater stream sediments and probably catalyzed by a cryptic sulfur cycle involving nitrogen species, in which the sulfur products from sulfate reduction are immediately removed by side reactions and not detectable by geochemical measurements alone. Similar experiments in SRS sediments, however, demonstrated little interaction between nitrogen and sulfur cycling microorganisms. Sulfate reduction was impacted by the addition of more thermodynamically favorable electron acceptors, suggesting either that iron-reducing microorganisms outcompeted sulfate-reducing microorganisms for organic substrate, depleting the stock of electron donor available for sulfate reduction, or that the cryptic sulfur cycle was shunted by the precipitation of FeS generated as a result of the abiotic reduction of iron oxides by dissolved sulfide. A diagnostic modeling exercise was conducted to further investigate the competition between terminal electron accepting processes. As conventional kinetic models typically do not account for cryptic cycles and used inaccurate formulations to describe competition between microbial communities, new metabolic rate laws were developed that explicitly express the electron acceptor-specific enzyme of each energetically favorable metabolic process based on gene abundance detected in the incubations. The model was tested with the sediment slurry incubation data to determine whether substrate competition could explain the decrease in sulfate reduction observed in the presence of iron oxide competitor. The model was able to reproduce geochemical concentrations really well in each treatment once the model was calibrated with the unamended control, suggesting that microbial competition was indeed driven by thermodynamic considerations. Overall, carbon remineralization processes and rates will be reproduced much more realistically with the new metabolic rate laws.
54 ENVIRONMENTAL SCIENCES↗