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At least 541 records · Page 30

Exhaust emissions survey of a turbofan engine for flame holder swirl type augmentors at simulated altitude flight conditions

Emissions of carbon dioxide, total oxides of nitrogen, unburned hydrocarbons, and carbon monoxide from an F100 afterburning two spool turbofan engine at simulated flight conditions are reported. Tests were run at Mach 0.8 at altitudes of 10.97 and 13.71 km (36,000 and 45,000 ft), and at Mach 1.2 at 13.71 km (45,000 ft). Emission measurements were made from intermediate power (nonafterburning) through maximum afterburning, using a single point gas sample probe traversed across the horizontal diameter of the exhaust nozzle. The data show that emissions vary with flight speed, altitude, power level, and radial position across the nozzle. Carbon monoxide emissions were low for intermediate and partial afterburning power. Unburned hydrocarbons were near zero for most of the simulated flight conditions. At maximum afterburning, there were regions of NOx deficiency in regions of high CO. The results suggest that the low NOx levels observed in the tests are a result of interaction with high CO in the thermal converter. CO2 emissions were proportional to local fuel air ratio for all test conditions.

Moss, J. E., Jr.↗

CO 2 Transport Infrastructure Outlook in the United States

Carbon capture and storage (CCS) represents one of the most important methods to mitigate anthropogenic carbon emissions at a large scale, playing a key role in meeting climate change targets (Bui et al., 2018) and for net-zero CO 2 by 2050 scenarios in the United States (Browning et al., 2023). This technology involves capturing CO 2 emissions from industrial processes, transporting them via pipelines, trucks, rails, or ships, and ultimately storing them in underground geological sites, such as saline aquifers or depleted oil reservoirs. Thus, to encourage carbon reduction initiatives, the U.S. Congress enacted the Bipartisan Budget Act in 2018, reforming the 45Q tax credit to benefit operators storing CO 2 in geologic formations (Jones and Sherlock, 2021). Additionally, the 2022 Inflation Reduction Act further expanded these incentives, providing additional support for CCS initiatives (Hackett and Kuehn, 2023). Although numerous studies describe the importance of optimal CO 2 transportation to support the decision-making of CCS projects aligned with the objective of net-zero emissions by 2050 (Abramson and Christensen, 2021; Chen and Pawar, 2023; Greig and Pascale, 2021), further efforts are required to optimize the transport infrastructure for national-scale CCS deployment. Therefore, in this study, we examine three nationwide scenarios with the SimCCS 3.0 tool (Ma et al., 2022, 2023, 2024) along with a novel geospatial splitting approach developed by Velasco-Lozano et al. (Velasco- Lozano et al., 2024a, 2024b). We present optimized pipeline networks that meet the dynamic evolution of annual capture amounts, describing the required total pipeline lengths at each stage as a function of the pipeline diameters. Thus, the cases presented demonstrate the feasibility of CO 2 pipeline infrastructure for large-scale CCS projects.

54 ENVIRONMENTAL SCIENCES↗

Estimating the Value of Nuclear Integrated Hydrogen Production and the Dependency of Electricity and Hydrogen Markets on Natural Gas

Producing low carbon Hydrogen at a competitive price is one of the challenges to hydrogen being part of the solution to reach net-zero emission targets set by the U.S. DOE by 2050. With projected near-term improvements in technology, hydrogen production via solid oxide electrolysis cell (SOEC) / high-temperature steam electrolysis (HTSE) integrated with existing light water reactor (LWR) Nuclear Power Plants (NPP-HTSE) can produce carbon-free hydrogen competitively. In the near term, a 10-year production tax credit (PTC) found in the Inflation Reduction Act (IRA) has been passed, which will catalyze the development and improvement of hydrogen production technology to be competitive. The “1-1-1” target set by the U.S. DOE is to reduce the cost of carbon-free hydrogen by 80% to $1 per kilogram in 1 decade. Several models are available to analyze the profitability, opportunity, and technical capability of NPP-HTSE systems. In order of complexity from most complex to least complex some of these models include: RAVEN/HERON, process models using Aspen HYSYS and capital expense estimations using Aspen Process Economic Analyzer (APEA) and levelized cost of hydrogen (LCOH) calculation using the H2A model (Hydrogen Analysis Model), and custom spread sheets built by the interested party. Though some of the more advanced existing models provide detailed analysis to complex grid integrated problems, they also can take considerable time to setup and run. These advanced models are well suited to complex grid integrated analysis and the consideration of flexibility and variability of regulated and de-regulated electricity price and advanced estimation of capital and operating expenses and heat and material balances.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

A photovoltaic catenary-tent array for the Martian surface

To provide electrical power during an exploration mission to Mars, a deployable tent-shaped structure with a flexible photovoltaic (PV) blanket is proposed. The array is designed with a self-deploying mechanism utilizing pressurized gas expansion. The structural design for the array uses a combination of cables, beams, and columns to support and deploy the PV blanket. Under the force of gravity a cable carrying a uniform load will take the shape of a catenary curve. A catenary-tent collector is self shadowing which must be taken into account in the solar radiation calculation. The shape and the area of the shadow on the array was calculated and used in the determination of the global radiation on the array. The PV blanket shape and structure dimension were optimized to achieve a configuration which maximizes the specific power (W/kg). The optimization was performed for four types of PV blankets (Si, GaAs/Ge, GaAs CLEFT, and amorphous Si) and four types of structure materials (Carbon composite, Aramid Fiber composite, Aluminum, and Magnesium). The results show that the catenary shape of the PV blanket, which produces the highest specific power, corresponds to zero end angle at the base with respect to the horizontal. The tent angle is determined by the combined effect of the array structure specific mass and the PV blanket output power. The combination of carbon composite structural material and GaAs CLEFT solar cells produce the highest specific power. The study was carried out for two sites on Mars corresponding to the Viking Lander locations. The designs were also compared for summer, winter, and yearly operation.

Crutchik, M.↗

Determining the hydration energetics on carbon-supported Ru catalysts: An adsorption calorimetry and density functional theory study

Fundamental knowledge on the energetics at the interface between a water layer and a metal catalyst is essential so as to understand the roles that water can play in the synthesis, activation and regeneration of noble metal-based catalysts. Here, we report the direct measurement of the enthalpy of water adsorption (Δh ads ) on activated carbon (C) and activated C-supported Ru nanoparticles, which are promising catalyst as applied to the hydrogenation/hydrodeoxygenation (HDO) of oxygenates (phenolics, aldehydes, etc.). Specifically, the near-zero coverage enthalpy of water adsorption on a C-supported Ru catalyst is -75.3 ± 0.4 kJ/(mol water), suggesting favorable water–metal binding. This is much more exothermic than that on C, which has an enthalpy of adsorption of -50.3 ± 1.3 kJ/(mol water). Despite the favorable initial binding, the magnitudes of enthalpies of water condensation on C and Ru-C indicate that overall, their surfaces are both hydrophobic. Moreover, the experimentally-measured near-zero coverage water adsorption enthalpy at the Ru sites is in very good agreement with our density functional theory based calculations. At low coverages, we obtain a water binding energy of -61.7 kJ/(mol water), which increases to -78.1 kJ/(mol water) at saturation. Complementary results are also obtained from a thermal analysis, which employed a thermogravimetric analysis–differential scanning calorimetry–mass spectrometry (TG-DSC-MS), a spectroscopic investigation using ex situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and a morphological evaluation with transmission electron microscopy (TEM). We point out that in carbon-supported metal catalysts, such as Ru-C, a strong hydration at near-zero coverage and relative weak water-surface interactions occurs upon saturation. Such heterogeneity is essential and crucial for catalytic hydrogenation/HDO reactions that involve balanced interactions among the water-rich reactant mixture and nonpolar organic products.

09 BIOMASS FUELS↗

Additional Aviation Sustainability Strategies

Emissions from the aviation sector are expected to grow significantly in the next few decades due to growing demand for aviation. The U.S. fleet size has increased significantly in the past 20 years, growing from 2,132 aircraft to 5,485 aircraft. Similarly from 1990 to 2019, aviation emissions more than doubled, growing faster than any other transportation mode. These emissions include carbon dioxide (CO2), as well as non-CO2 sources including nitrogen oxides (NOx), sulfur dioxide (SO2), water (H2O), and particulate matter (soot). However, this report focuses specifically on CO2 emissions because the impacts from CO2 are well-understood and long-lived. There are also many climate goals tied to CO2 emissions, including the US Aviation Climate Action Plan which is pushing for net-zero in 2050. CO2 is a greenhouse, or heat-trapping, gas that comes from the extraction and burning of fossil fuels, from wildfires, and natural processes like volcanoes. Greenhouse gases absorb heat radiating from the Earth’s surface and release it in all directions, including back toward Earth’s surface. By adding more CO2 to the atmosphere, humans amplify the natural greenhouse effect, causing global temperature to rise. Since the onset of industrial times in 1750, human activities have raised atmospheric CO2 by 50%. Considering this challenge, the United States has set a climate goal to achieve net-zero CO2 emissions in the U.S. aviation sector by 2050 to reduce the environmental impact of aviation. Net-zero emissions refers to the amount of greenhouse gases (GHGs), such as CO2, methane or SO2, that are removed from the atmosphere being equal to those emitted by human activity. This contrasts with carbon-neutrality, which refers to no net release of carbon dioxide to the atmosphere, especially through offsetting emissions, that could be accomplished through a series of actions. As of 2022, the goal of net-zero has been adopted by much of the aviation industry including multiple airlines and countries. To reach net-zero by 2050, sustainable aviation fuels (SAFs) are identified as the technology that could provide the greatest impact within this timeframe. However, certain challenges may limit the production and/or adoption of SAFs in the marketplace, such as competition for feedstocks, production capacity, and high cost. In this case, SAFs would be insufficient to meet the net-zero CO2 emission goals. Therefore, in addition to SAFs, other strategies will be needed to close the gap on emissions produced as a result of SAF shortfalls or to enhance the impact of SAFs on reducing emissions. NASA’s Aeronautics Research Mission Directorate (ARMD) aims to examine these additional pathways to explore how its research may best contribute to the realization of net-zero emissions by 2050. Specifically, this effort considers strategies that can reduce emissions in the aviation sector in combination with the use of SAFs and carbon offsets while still meeting projected passenger demand. The strategies considered are not only feasible but also could be operationally scalable by 2050. The goal of this report is to investigate additional strategies such as alternative flight and ground operations, providing insight into the CO2 emission reduction potential and feasibility of strategy implementation by 2050.

Carbon Emissions↗

Measurement of tropospheric carbon monoxide using gas filter radiometers

The measurement of tropospheric carbon monoxide with gas filter radiometers is examined on the basis of the MAPS experiment. The performance characteristics of an instrument that uses the MAPS detectors, broadband filters, and gas cells in a system similar to the GASCOFIL system described by Morrow and Nicholls (1985) is determined. The signal function for two carbon monoxide channels of the MAPS instrument as it was flown in 1981 is shown. The measurements of the lower pressure channel are weighted to a higher altitude. The signal function, when integrated over altitude and multiplied by the normalization constant, yields the value of the signal. Both signal functions approach zero at the top because the gas concentration approaches zero. The present data reduction technique assumes that there are no clouds in the field of view. If clouds are present, the inferred carbon monoxide mixing ratio is too high, and those points must be rejected from the data set.

Reichle, Henry G., Jr.↗

Environmental risks and opportunities of orphaned oil and gas wells in the United States

Abstract Hundreds of thousands of documented and undocumented orphaned oil and gas wells exist in the United States (U.S.). These wells have the potential to contaminate water supplies, degrade ecosystems, and emit methane and other air pollutants. Thus, orphaned wells present risks to climate stability and to environmental and human health, which can be reduced by plugging. To quantify environmental risks and opportunities of well plugging at the national level, we analyze data on 81 857 documented orphaned wells across the U.S. We find that > 4.6 million people live within 1 km of a documented orphaned well. 35% of the documented orphaned wells are located within 1 km of a domestic groundwater well, yet only 8% of the wells have groundwater quality data within a 1 km radius. Methane emissions from the documented orphaned wells represent approximately 3%–6% of total U.S. methane emissions from abandoned oil and gas wells, but this estimate is based on measurements at < 0.03% of U.S. abandoned wells. 91% of the documented orphaned wells overlie formations favorable for geologic storage of carbon dioxide and hydrogen, meaning that orphaned well plugging can reduce leakage risks from future storage projects. Finally, we estimate plugging costs for documented orphaned wells to exceed the $4.7 billion federal funding by 30%–80%, emphasizing the importance of prioritizing federal spending on wells with large remediation benefits. Overall, environmental monitoring data are not extensive enough to quantify risks, especially those related to air and water quality and human health. Plugging orphaned wells can provide opportunities for geologic storage of carbon dioxide and hydrogen and geothermal energy development, thereby facilitating efforts to transition to net-zero energy systems. Our analysis on environmental risks and opportunities of orphaned wells provides a framework that can be used to manage the millions of documented and undocumented orphaned wells in the U.S. and abroad.

54 ENVIRONMENTAL SCIENCES↗

Materials Data on CO by Materials Project

CO is alpha carbon monoxide structured and crystallizes in the cubic P2_13 space group. The structure is zero-dimensional and consists of four formaldehyde molecules. C2+ is bonded in a single-bond geometry to one O2- atom. The C–O bond length is 1.14 Å. O2- is bonded in a single-bond geometry to one C2+ atom.

36 MATERIALS SCIENCE↗

Materials Data on Se2NCl3 by Materials Project

N2(Se2Cl3)2 is alpha carbon monoxide structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four ammonia molecules and four Se2Cl3 clusters. In each Se2Cl3 cluster, there are two inequivalent Se1+ sites. In the first Se1+ site, Se1+ is bonded in a distorted linear geometry to two Cl1- atoms. There are one shorter (2.22 Å) and one longer (2.70 Å) Se–Cl bond lengths. In the second Se1+ site, Se1+ is bonded in a distorted linear geometry to two Cl1- atoms. There are one shorter (2.25 Å) and one longer (2.64 Å) Se–Cl bond lengths. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two Se1+ atoms. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Se1+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Se1+ atom.

36 MATERIALS SCIENCE↗

Heat-transfer distributions for biconics at incidence in hypersonic-hypervelocity real-gas flows

Laminar heat-transfer distributions were measured on spherically blunted, 13/7 deg straight and bent biconics at freestream velocities from 4.5 to 6.9 km/s and Mach numbers from 6 to 9. The flows were generated in the NASA's Langley Expansion Tube using helium, nitrogen, air, and carbon dioxide; angle of attack, referenced to the axis of the aft cone, was varied from zero to 20 deg. The penalty in windward heating to the fore cone due to the 7-deg nose bend diminished rapidly with increasing angle of attack and was only 10 to 20 percent at the design trim angle of attack of 20 deg. Leeward heating initially decreased, then increased, with increasing angle of attack. Windward heating rates predicted with a computer code that solves the parabolized Navier-Stokes equations were in good agreement with measurements for helium and air. The study used a 1.9-percent scale model of the proposed generic planetary vehicle and is directly applicable to the orbital transfer vehicle, which incorporates a spherically blunted biconic.

Miller, C. G.↗

Sustainable Valorization of CO2 through Nuclear Power-to-X Pathways

Some of the issues concerning energy security and climate change can be addressed by employing nuclear power (NP) to supply the energy required for the conversion of carbon dioxide (CO2) into chemicals, products, and materials. Nuclear energy represents a neutral carbon source that can be generated sustainably, reliably, and consistently. Nuclear power plants (NPPs) could supply energy in the form of heat, electricity, and ionizing radiation to drive CO2 chemical reactions underpinning NP-to-X type of pathways. CO2 conversion processes are either commercially available or emerging technologies at different developmental maturity stages. This work reviews the published literature (articles and patents) that reports R&D results and the understanding and development of chemical reactions and processes, as well as the efforts in integrating NPPs and chemical processes (CPs). As will be made evident, a new industrial era for the manufacturing of decarbonized chemicals, products, and materials will be possible by developing and implementing new (more energy- and carbon-efficient) processes responding to the NP-to-X pathways. This new decarbonizing platform not only contributes to achieving net zero goals but also broadens the NPP product beyond electricity.

08 HYDROGEN↗

Identification of opportunities for integrating chemical processes for carbon (dioxide) utilization to nuclear power plants

The energy and industrial sectors are responsible for more than 75% of global carbon dioxide emissions, which are primary contributors to climate change. Decarbonization strategies to reduce overall carbon dioxide emissions are urgently needed. Among the numerous decarbonization strategies that are being defined and implemented, a particular strategy of interest for the present work is “the Re-X or zero waste” strategy, which involves recycling, reuse, repurposing, and remanufacturing of industrial emissions, by-products, and waste in general. A circular value chain or Circular Economy is embedded within this strategy. In a circular carbon economy, efficient reuse of emitted carbon dioxide is considered. However, the stability of carbon dioxide implies the requirement of significant amounts of energy for its transformation into value-added chemicals or products, which must be supplied by low carbon emitting energy sources. Nuclear power plants are low carbon energy sources that, additionally to electricity, could also supply heat and radiation for chemical transformations. This work identifies the opportunities and challenges for the development of integrated energy systems to upgrade and transform carbon dioxide, involving chemical and nuclear energy. The analysis encompasses possible use of the different forms of energy that can be obtain from nuclear reactors (i.e., radiation, electricity, and heat), by reviewing the published literature on potential routes for its conversion. Overall, our review indicates that an universal technology of the one-fits-all solution-type is an utopic dream. Instead, a suite of (contaminants tolerant) technologies for processing various concentrations CO 2 and producing a variety of products is currently needed.

08 HYDROGEN↗

Techno-economic Analysis and Life-Cycle Analysis of Renewable Diesel Fuels Produced with Waste Feedstocks

Wet waste feedstocks represent an important category of resources that could be utilized to produce biofuels. Diversion of the wet waste resources from going through conventional waste management practices to utilization as feedstocks for energy production also benefits from avoided cost and pollutant emissions of waste management and disposal. This study investigates the economic and environmental implications of producing bio-blendstocks for mixing controlled compression ignition (MCCI) engines from two waste-to-fuel pathways: hydroprocessed esters and fatty acids (HEFA) from yellow grease, and swine manure hydrothermal liquefaction (HTL) followed by biocrude upgrading. Detailed process models were developed for both pathways, which informed the techno-economic analysis (TEA) and life-cycle analysis (LCA). Conventional swine manure management practice was also modeled in detail as the business-as-usual (BAU) scenario for the swine manure HTL pathway. The estimated minimum fuel selling prices (MFSP) were $4.47/gasoline gallon equivalent (GGE) and $3.57/GGE for the yellow grease to HEFA and swine manure HTL pathways, respectively. The life-cycle greenhouse gas (GHG) emissions of the two pathways were 11.2 and -33.3 g CO2e/MJ, respectively, for the yellow grease to HEFA and swine manure HTL pathways. The credits of avoided emissions from conventional swine manure management were the main reason for the negative GHG emissions of the swine manure HTL pathway. The marginal GHG emissions abatement costs were estimated to be $100 – $253/tonne CO2e and $5 – $103/tonne CO2e for the yellow grease HEFA and swine manure HTL pathways, respectively, for a diesel price ranging between $2.0/GGE and $3.5/GGE. Since the yellow grease HEFA pathway is already commercialized, it can benefit from the $200/tonne carbon credit in the California Low Carbon Fuel Standard (LCFS) market, which could help the yellow grease HEFA pathway to achieve near-zero marginal GHG emissions abatement cost.

renewable diesel, techno economic analysis, life c↗

Developing new pathways for energy and environmental decision-making in India: a review

Abstract India faces a dual challenge of economic development and responding to climate change. Although India’s per capita emissions are well below global average, the country is one of the world’s largest greenhouse gas emitters. Indian policymakers and stakeholders require high-quality data and research to assess low-emissions, sustainable development strategies. Peer-reviewed literature is a key source of this information and also a key venue for conversation amongst research leaders. This paper examines the recent peer-reviewed literature on India’s 2030 and 2050 pathways. We conducted a systematic literature review to identify key quantitative national modeling studies. From the 34 studies identified, we synthesized scenario data to draw common conclusions and identify critical research gaps. The main focus was on examining the coverage and the state of information available on low-carbon pathways. Overall, we find a few scenarios that are potentially consistent with a 2070 net-zero goal, but more limited assessment of pathways to reach net-zero emissions before this date. Mitigation pathways with greater ambition are required across all energy sectors to ensure a smooth transition to net-zero emissions by or before 2070. The scenarios confirm that reducing emissions to below 2 GtCO 2 yr −1 by mid-century would necessitate significant transformations of the Indian energy sector, such as, a decrease in unabated coal power capacity, transportation modal shift, and industrial process switching. The assessment also finds substantial differences in final energy estimates reported across studies, particularly in transportation. The lack of consistency in, and transparency about underlying drivers, assumptions, and even outputs across studies points to the critical need for the sorts of coordinated, multi-model studies that have proven exceptionally valuable for decision makers in other major emitting countries.

54 ENVIRONMENTAL SCIENCES↗

Materials Data on CN by Materials Project

CN is alpha carbon monoxide-like structured and crystallizes in the orthorhombic Pbca space group. The structure is zero-dimensional and consists of eight hydrogen cyanide molecules. C3+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.17 Å. N3- is bonded in a single-bond geometry to one C3+ atom.

36 MATERIALS SCIENCE↗

Materials Data on Se2NCl3 by Materials Project

N2(Se2Cl3)2 is alpha carbon monoxide-like structured and crystallizes in the orthorhombic Pbca space group. The structure is zero-dimensional and consists of sixteen ammonia molecules and sixteen Se2Cl3 clusters. In each Se2Cl3 cluster, there are two inequivalent Se1+ sites. In the first Se1+ site, Se1+ is bonded in a distorted linear geometry to two Cl1- atoms. There are one shorter (2.27 Å) and one longer (2.57 Å) Se–Cl bond lengths. In the second Se1+ site, Se1+ is bonded in a distorted linear geometry to two Cl1- atoms. There are one shorter (2.25 Å) and one longer (2.62 Å) Se–Cl bond lengths. There are three inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two Se1+ atoms. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Se1+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Se1+ atom.

36 MATERIALS SCIENCE↗

Materials Data on TeS4(NCl)4 by Materials Project

(NS)4TeCl4 is alpha carbon monoxide-like structured and crystallizes in the monoclinic Cc space group. The structure is zero-dimensional and consists of four 1,3,5,7,2,4,6,8-tetrathiatetrazocane molecules and four TeCl4 clusters. In each TeCl4 cluster, Te4+ is bonded in a distorted rectangular see-saw-like geometry to four Cl1- atoms. There are a spread of Te–Cl bond distances ranging from 2.48–2.54 Å. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Te4+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Te4+ atom. In the third Cl1- site, Cl1- is bonded in a distorted single-bond geometry to one Te4+ atom. In the fourth Cl1- site, Cl1- is bonded in a single-bond geometry to one Te4+ atom.

36 MATERIALS SCIENCE↗