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DOE OSTI2025

Life cycle assessment of a novel gas switching reforming for sustainable hydrogen production with CO2 capture

Gas switching reforming for hydrogen production (GSR-H2) presents an efficient, low-carbon hydrogen production method that incorporates integrated carbon capture, offering efficiency gains over traditional methods such as proton exchange membrane (PEM) electrolysis, steam methane reforming (SMR) and the newer method of chemical looping reforming (CLR). GSR-H2 has been demonstrated in lab scale which operates as an exothermic process that eliminates the need for additional natural gas combustion, using its own waste heat to generate process steam and partially offset energy usage through electricity production. Beyond its thermal self-sufficiency, GSR-H2 advances upon CLR by integrating all reaction stages within a single reactor cluster, eliminating the complexities of solid circulation, reducing capital costs, and enhancing overall process efficiency. This streamlined design simplifies scale-up and enables inherent CO2 separation with minimal energy penalty, making GSR-H2 a highly competitive pathway for low-carbon hydrogen production. This study presents the first life cycle assessment (LCA) of GSR-H2, offering a novel evaluation of this new process’s environmental impacts across diverse energy scenarios. Key findings reveal that in the renewables-powered scenario, GSR-H2 achieves a GWP of 2.77 kg CO2 eq per kg H2, a substantial improvement over SMR’s 10.4 kg CO2 eq and close to the low emissions of CLR (1.84 kg CO2 eq) and PEM electrolysis (1.85 kg CO2 eq). These results demonstrate GSR-H2’s competitive advantage as a lower-emission alternative, combining design simplicity and efficiency gains, especially in renewable-integrated systems. These results establish GSR-H2 as a competitive, scalable option for hydrogen production, particularly in decarbonization efforts.

03 NATURAL GAS↗

DOE OSTI2020

Materials Data on Be(B3H7)2 by Materials Project

BeB5H13BH is alpha carbon monoxide-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four boranediylradical molecules and four BeB5H13 clusters. In each BeB5H13 cluster, Be2+ is bonded in a 4-coordinate geometry to four H+0.71+ atoms. There are a spread of Be–H bond distances ranging from 1.53–1.59 Å. There are five inequivalent B2- sites. In the first B2- site, B2- is bonded in a distorted trigonal non-coplanar geometry to three H+0.71+ atoms. There are a spread of B–H bond distances ranging from 1.20–1.34 Å. In the second B2- site, B2- is bonded in a distorted trigonal non-coplanar geometry to three H+0.71+ atoms. There are a spread of B–H bond distances ranging from 1.19–1.35 Å. In the third B2- site, B2- is bonded in a distorted trigonal non-coplanar geometry to three H+0.71+ atoms. There are a spread of B–H bond distances ranging from 1.19–1.35 Å. In the fourth B2- site, B2- is bonded in a distorted trigonal non-coplanar geometry to three H+0.71+ atoms. There are a spread of B–H bond distances ranging from 1.20–1.34 Å. In the fifth B2- site, B2- is bonded in a tetrahedral geometry to four H+0.71+ atoms. There are a spread of B–H bond distances ranging from 1.20–1.26 Å. There are thirteen inequivalent H+0.71+ sites. In the first H+0.71+ site, H+0.71+ is bonded in a single-bond geometry to one B2- atom. In the second H+0.71+ site, H+0.71+ is bonded in a single-bond geometry to one B2- atom. In the third H+0.71+ site, H+0.71+ is bonded in a single-bond geometry to one B2- atom. In the fourth H+0.71+ site, H+0.71+ is bonded in an L-shaped geometry to one Be2+ and one B2- atom. In the fifth H+0.71+ site, H+0.71+ is bonded in a single-bond geometry to one B2- atom. In the sixth H+0.71+ site, H+0.71+ is bonded in an L-shaped geometry to one Be2+ and one B2- atom. In the seventh H+0.71+ site, H+0.71+ is bonded in an L-shaped geometry to one Be2+ and one B2- atom. In the eighth H+0.71+ site, H+0.71+ is bonded in an L-shaped geometry to one Be2+ and one B2- atom. In the ninth H+0.71+ site, H+0.71+ is bonded in a single-bond geometry to one B2- atom. In the tenth H+0.71+ site, H+0.71+ is bonded in an L-shaped geometry to two B2- atoms. In the eleventh H+0.71+ site, H+0.71+ is bonded in an L-shaped geometry to two B2- atoms. In the twelfth H+0.71+ site, H+0.71+ is bonded in an L-shaped geometry to two B2- atoms. In the thirteenth H+0.71+ site, H+0.71+ is bonded in a single-bond geometry to one B2- atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Se2NCl5 by Materials Project

N2(Se2Cl5)2 is alpha carbon monoxide-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of eight ammonia molecules and eight Se2Cl5 clusters. In four of the Se2Cl5 clusters, there are two inequivalent Se1+ sites. In the first Se1+ site, Se1+ is bonded in a 3-coordinate geometry to three Cl1- atoms. There are a spread of Se–Cl bond distances ranging from 2.22–2.77 Å. In the second Se1+ site, Se1+ is bonded in a distorted T-shaped geometry to three Cl1- atoms. There are a spread of Se–Cl bond distances ranging from 2.24–2.70 Å. There are five inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Se1+ atom. 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. In the fourth Cl1- site, Cl1- is bonded in a single-bond geometry to one Se1+ atom. In the fifth Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two Se1+ atoms. In four of the Se2Cl5 clusters, there are two inequivalent Se1+ sites. In the first Se1+ site, Se1+ is bonded in a 3-coordinate geometry to three Cl1- atoms. There are a spread of Se–Cl bond distances ranging from 2.22–2.72 Å. In the second Se1+ site, Se1+ is bonded in a distorted T-shaped geometry to three Cl1- atoms. There are a spread of Se–Cl bond distances ranging from 2.22–2.71 Å. There are five inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Se1+ atom. 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. In the fourth Cl1- site, Cl1- is bonded in a 2-coordinate geometry to two Se1+ atoms. In the fifth Cl1- site, Cl1- is bonded in a single-bond geometry to one Se1+ atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Stochastic nonlinear analysis of unidirectional fiber composites using image-based microstructural uncertainty quantification

Here, we present a data-driven nonlinear uncertainty quantification and propagation framework to study the microstructure-induced stochastic performance of unidirectional (UD) carbon fiber reinforced polymer (CFRP) composites. The proposed approach integrates (1) microscopic image characterization, (2) stochastic microstructure reconstruction, and (3) efficient multiscale finite element simulations enabled by self-consistent clustering (SCA) analysis. To model the complex microstructural variability, the proposed UQ methods take the non-Gaussian uncertainty sources into account through a distribution-free sampling approach leveraging nonparametric and asymptotic statistical tools. A hierarchical conditional sampling strategy enables the simultaneous sampling of multiple sources of uncertainties. Our approach provides insights into the impact of microstructural variabilities, which are shown to have an increasing impact on the nonlinear responses of UD CFRP parts under progressive compression loading and ultimately on the failure rate over time. We discover that before CFRP parts start to fail, a characteristic time period emerges with distinctive uncertainty distributions specific to the microstructure variability and the probability of failure. Identifying the failure time period is crucial to the reliability prediction, which is an essential component of CFRP design.

36 MATERIALS SCIENCE↗

NASA NTRS1984

Structural characterizaiton and gas reactions of small metal particles by high-resolution, in-situ TEM and TED

The existing in-situ transmission electron microscopy (TEM) facility was improved by adding a separately pumped mini-specimen chamber. The chamber contains wire-evaporation sources for three metals and a specimen heater for moderate substrate temperatures. A sample introduction device was constructed, installed, and tested, facilitating rapid introduction of a specimen into the mini-chamber while maintaining the background pressure in that chamber in the 10(-9) millibar range. Small particles and clusters of Pd, grown by deposition from the vapor phase in an in-situ TEM facility on amorphous and crystalline support films of alumina and on ultra-thin carbon films, were analyzed by conventional high-resolution TEM and image analysis in terms of detectability, number density, and size distribution. The smallest particles that could be detected and counted contained no more than 6 atoms; size determinations could be made for particles 1 nm in diameter. The influence of various oxygen plasma treatments, annealing treatments, and of increasing the substrate temperature during deposition was investigated. The TEM technique was employed to demonstrate that under otherwise identica l conditions the lattice parameter of Pd particles in the 1 to 2 nm size range and supported in random orientation on ex-situ prepared mica films is expanded by some 3% when compared to 5 nm size particles. It is believed that this expansion is neither a small-particle diffraction effect nor due to pseudomorphism, but that it is due to a annealing-induced transformation of the small as-deposited particles with predominantly composite crystal structures into larger particles with true f.c.c. structure and thus inherently smaller lattice parameter.

Source record↗

DOE OSTI2021

Carbon capture, utilization, and storage hub development on the Gulf Coast

Abstract The Gulf Coast of the United States hosts diverse power generation, refining, and petrochemical processing facilities, resulting in the nation's largest volumetric concentration of industrial CO 2 emissions, rivaled only by the Ohio River Valley. These emissions sources are concentrated in specific industrial clusters that allow combining emissions streams to achieve economies of scale. The region is currently undergoing globally significant industrial expansion and investment as a result of abundant and inexpensive regional unconventional natural gas availability, and is a growing exporter of liquefied natural gas (LNG). Opportunities to integrate CO 2 emission management within the diverse energy chains in the region are volumetrically significant and include both concentrated and dilute sources. Significant examples of capture, transport, and storage exist. Offshore storage is particularly attractive, as it provides simplified land leasing models (single governmental land owner), proven reservoir quality, and presents fewer risks to both protected groundwater and populated areas. Projects can now take advantage of recently expanded opportunities under section 45Q of the Internal Revenue Service tax code. The region continues to evolve as an active carbon‐handling hub, and is uniquely suited to justify additional investment in carbon capture, utilization, and storage (CCUS) technologies via a large‐scale integrated project development. Continued development of integrated projects will allow the region to continue to grow economically within its strong fossil‐fuel handling competence focus while advancing low‐carbon energy technologies that maintain globally competitiveness. © 2021 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd.

45Q↗

DOE OSTI2021

Toward Quantum Confinement in Graphitic Carbon Nitride-Based Polymeric Monolayers

raphitic carbon nitride (g-C 3 N 4 ) has garnered much attention due to its potential as an efficient metal-free photocatalyst. This study examines the evolution of properties in zero-dimensional quantum dots up to sizable clusters that mimic extended g-C 3 N 4 monolayers. We employ density functional theory to investigate systematically the structural, electronic, and optical properties of the g-C 3 N 4 -based melamine and heptazine building blocks using a “bottom-up” construction of polymeric monolayers. The results from our computations indicate that the melamine- and heptazine-based polymeric g-C 3 N 4 systems must be reduced to at least 2.74 and 4.00 nm, respectively, to observe an increase of its optical gap with a size reduction. The present study also examines the nature of the electronic transitions exhibited by g-C 3 N 4 -based monolayers through full natural transition orbital and density of state analyses. Furthermore, the most promising sites for water splitting and subsequent chemical doping studies are identified, which generally correspond to the nitrogen and carbon atoms, respectively.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2020

Local-scale Arctic tundra heterogeneity affects regional-scale carbon dynamics

In northern Alaska nearly 65% of the terrestrial surface is composed of polygonal ground, where geomorphic tundra landforms disproportionately influence carbon and nutrient cycling over fine spatial scales. Process-based biogeochemical models used for local to Pan-Arctic projections of ecological responses to climate change typically operate at coarse-scales (1km 2 –0.5°) at which fine-scale (<1km 2 ) tundra heterogeneity is often aggregated to the dominant land cover unit. Here, we evaluate the importance of tundra heterogeneity for representing soil carbon dynamics at fine to coarse spatial scales. We leveraged the legacy of data collected near Utqiagvik, Alaska between 1973 and 2016 for model initiation, parameterization, and validation. Simulation uncertainty increased with a reduced representation of tundra heterogeneity and coarsening of spatial scale. Hierarchical cluster analysis of an ensemble of 21 st -century simulations reveals that a minimum of two tundra landforms (dry and wet) and a maximum of 4km 2 spatial scale is necessary for minimizing uncertainties (<10%) in regional to Pan-Arctic modeling applications.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2022

Revisiting constraints on asymmetric dark matter from collapse in white dwarf stars

The runaway collapse phase of a small dark matter cluster inside a white dwarf star encompasses a reversible stage, where heat can be transferred back and forth between nuclear and dark matter. Induced nuclear burning phases are stable and early carbon depletion undermines previous claims of type Ia supernova ignition. Instead, mini black holes are formed at the center of the star that either evaporate or accrete stellar material until a macroscopic sub-Chandrasekhar-mass black hole is formed. In the latter case, a 0.1 to 1 second lasting electromagnetic transient signal can be detected upon ejection of the white dwarf’s potential magnetic field. Binary systems that transmute to black holes and subsequently merge emit gravitational waves. Advanced LIGO should detect one such sub-Chandrasekhar binary black hole inspiral per year, while future Einstein telescope-like facilities will detect thousands per year. The effective spin parameter distribution is peaked at 0.2 and permits future studies to disentangle from primordial sub-Chandrasekhar black holes. Such signatures are compatible with current direct detection constraints, as well as with neutron star constraints in the case of bosonic dark matter, even though they remain in conflict with the fermionic case for part of the parameter space.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2020

Materials Data on LiSi4H27(C3O)3 by Materials Project

LiSi3H27(C3O)3Si is alpha carbon monoxide-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four silicon molecules and four LiSi3H27(C3O)3 clusters. In each LiSi3H27(C3O)3 cluster, Li1+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is one shorter (1.99 Å) and two longer (2.00 Å) Li–O bond length. There are three inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded in a trigonal non-coplanar geometry to two C4- and one O2- atom. Both Si–C bond lengths are 1.89 Å. The Si–O bond length is 1.73 Å. In the second Si4+ site, Si4+ is bonded in a trigonal non-coplanar geometry to two C4- and one O2- atom. Both Si–C bond lengths are 1.89 Å. The Si–O bond length is 1.73 Å. In the third Si4+ site, Si4+ is bonded in a trigonal non-coplanar geometry to two C4- and one O2- atom. Both Si–C bond lengths are 1.89 Å. The Si–O bond length is 1.73 Å. There are nine inequivalent C4- sites. In the first C4- site, C4- is bonded in a tetrahedral geometry to three H+0.93+ and one O2- atom. All C–H bond lengths are 1.10 Å. The C–O bond length is 1.44 Å. In the second C4- site, C4- is bonded in a tetrahedral geometry to three H+0.93+ and one O2- atom. All C–H bond lengths are 1.10 Å. The C–O bond length is 1.44 Å. In the third C4- site, C4- is bonded in a tetrahedral geometry to three H+0.93+ and one O2- atom. All C–H bond lengths are 1.10 Å. The C–O bond length is 1.43 Å. In the fourth C4- site, C4- is bonded to one Si4+ and three H+0.93+ atoms to form corner-sharing CSiH3 tetrahedra. All C–H bond lengths are 1.10 Å. In the fifth C4- site, C4- is bonded to one Si4+ and three H+0.93+ atoms to form corner-sharing CSiH3 tetrahedra. All C–H bond lengths are 1.10 Å. In the sixth C4- site, C4- is bonded to one Si4+ and three H+0.93+ atoms to form corner-sharing CSiH3 tetrahedra. All C–H bond lengths are 1.10 Å. In the seventh C4- site, C4- is bonded to one Si4+ and three H+0.93+ atoms to form corner-sharing CSiH3 tetrahedra. All C–H bond lengths are 1.10 Å. In the eighth C4- site, C4- is bonded to one Si4+ and three H+0.93+ atoms to form corner-sharing CSiH3 tetrahedra. All C–H bond lengths are 1.10 Å. In the ninth C4- site, C4- is bonded to one Si4+ and three H+0.93+ atoms to form corner-sharing CSiH3 tetrahedra. All C–H bond lengths are 1.10 Å. There are twenty-seven inequivalent H+0.93+ sites. In the first H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the second H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the third H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the fourth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the fifth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the sixth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the seventh H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the eighth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the ninth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the tenth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the eleventh H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the twelfth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the thirteenth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the fourteenth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the fifteenth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the sixteenth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the seventeenth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the eighteenth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the nineteenth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the twentieth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the twenty-first H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the twenty-second H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the twenty-third H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the twenty-fourth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the twenty-fifth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the twenty-sixth H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. In the twenty-seventh H+0.93+ site, H+0.93+ is bonded in a single-bond geometry to one C4- atom. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to one Li1+, one Si4+, and one C4- atom. In the second O2- site, O2- is bonded in a trigonal planar geometry to one Li1+, one Si4+, and one C4- atom. In the third O2- site, O2- is bonded in a trigonal planar geometry to one Li1+, one Si4+, and one C4- atom.

36 MATERIALS SCIENCE↗

NASA NTRS2004

Functional Groups Based on Leaf Physiology: Are they Spatially and Temporally Robust?

The functional grouping hypothesis, which suggests that complexity in ecosystem function can be simplified by grouping species with similar responses, was tested in the Florida scrub habitat. Functional groups were identified based on how species in fire maintained Florida scrub regulate exchange of carbon and water with the atmosphere as indicated by both instantaneous gas exchange measurements and integrated measures of function (%N, delta C-13, delta N-15, C-N ratio). Using cluster analysis, five distinct physiologically-based functional groups were identified in the fire maintained scrub. These functional groups were tested to determine if they were robust spatially, temporally, and with management regime. Analysis of Similarities (ANOSIM), a non-parametric multivariate analysis, indicated that these five physiologically-based groupings were not altered by plot differences (R = -0.115, p = 0.893) or by the three different management regimes; prescribed burn, mechanically treated and burn, and fire-suppressed (R = 0.018, p = 0.349). The physiological groupings also remained robust between the two climatically different years 1999 and 2000 (R = -0.027, p = 0.725). Easy-to-measure morphological characteristics indicating functional groups would be more practical for scaling and modeling ecosystem processes than detailed gas-exchange measurements, therefore we tested a variety of morphological characteristics as functional indicators. A combination of non-parametric multivariate techniques (Hierarchical cluster analysis, non-metric Multi-Dimensional Scaling, and ANOSIM) were used to compare the ability of life form, leaf thickness, and specific leaf area classifications to identify the physiologically-based functional groups. Life form classifications (ANOSIM; R = 0.629, p 0.001) were able to depict the physiological groupings more adequately than either specific leaf area (ANOSIM; R = 0.426, p = 0.001) or leaf thickness (ANOSIM; R 0.344, p 0.001). The ability of life forms to depict the physiological groupings was improved by separating the parasitic Ximenia americana from the shrub category (ANOSIM; R = 0.794, p = 0.001). Therefore, a life form classification including parasites was determined to be a good indicator of the physiological processes of scrub species, and would be a useful method of grouping for scaling physiological processes to the ecosystem level.

Foster, Tammy E.↗

DOE OSTI2022

Simulation of multi-shell fullerenes using Machine-Learning Gaussian Approximation Potential

Multi-shell fullerenes ”buckyonions ” were simulated, starting from initially random configurations, using a density-functional-theory (DFT)-trained machine-learning carbon potential within the Gaussian Approximation Potential (GAP) Framework [Volker L. Deringer and Gábor Csányi, Phys. Rev. B 95, 094203 (2017)]. Fullerenes formed from seven different system sizes, ranging from 60 ~ 3774 atoms, were considered. The buckyonions are formed by clustering and layering starting from the outermost shell and proceeding inward. Inter-shell cohesion is partly due to interaction between delocalized π electrons protruding into the gallery. The energies of the models were validated ex post facto using density functional codes, VASP and SIESTA , revealing an energy difference within the range of 0.02 - 0.08 eV/atom after conjugate gradient energy convergence of the models was achieved with both methods.

74 ATOMIC AND MOLECULAR PHYSICS↗

NASA NTRS2003

StarBooster Demonstrator Cluster Configuration Analysis/Verification Program

In order to study the flight dynamics of the cluster configuration of two first stage boosters and upper-stage, flight-testing of subsonic sub-scale models has been undertaken using two glideback boosters launched on a center upper-stage. Three high power rockets clustered together were built and flown to demonstrate vertical launch, separation and horizontal recovery of the boosters. Although the boosters fly to conventional aircraft landing, the centerstage comes down separately under its own parachute. The goal of the project has been to collect data during separation and flight for comparison with a six degree of freedom simulation. The configuration for the delta wing canard boosters comes from a design by Starcraft Boosters, Inc. The subscale rockets were constructed of foam covered in carbon or fiberglass and were launched with commercially available solid rocket motors. The first set of boosters built were 3-ft tall with a 4-ft tall centerstage, and two additional sets of boosters were made that were each over 5-ft tall with a 7.5 ft centerstage. The rocket cluster is launched vertically, then after motor bum out the boosters are separated and flown to a horizontal landing under radio-control. An on-board data acquisition system recorded data during both the launch and glide phases of flight.

DeTurris, Dianne J.↗

DOE OSTI2024

Energy Clusters Offshore: A Technology Feasibility Review

Globally, governments, companies, and other organizations have committed to achieving net-zero emissions targets in the coming decades. To achieve decarbonization at the scale and pace required to meet these targets, future energy systems will need renewable energy to serve 100% of the existing direct electricity demand, support additional electrification, and decarbonize the wider economy. An energy cluster offshore (ECO) is a concept that seeks to meet this challenge by integrating and optimizing large-scale renewable electricity generation, storage, and fuel production technologies and pairing them with other complementary uses, such as carbon capture or water desalination. This research project explores the techno-economic feasibility of ECO concepts by taking a holistic view of complex, multidisciplinary hybrid plant designs while considering different configurations and objectives. We will outline the most promising technology combinations and configurations, their functional requirements, and opportunities for optimization.

14 SOLAR ENERGY↗

NASA NTRS1993

Infrared spectra of transition objects and the composition and evolution of carbon dust

We obtained IR (5-23 microns) spectra of five carbon-rich objects in transition from the asymptotic giant branch (AGB) to the planetary nebula stage of evolution. These spectra show a variety of IR emission features due to circumstellar materials. In particular, all sources show the 6.2 and '7.7' micron bands, commonly observed in PNs and ascribed to polycyclic aromatic hydrocarbon molecules (PAHs). Some transition nebulae also show a strong 6-9 micron plateau characteristic for larger PAH clusters (about 400 C-atoms). A new broad feature at about 8.8 microns is present in some sources. This feature is distinctly different from the 8.6-micron PAH feature. This 8.8-micron feature may be present in the spectra of C-rich giants as well, but is not evident in PN spectra. We suggest that large amorphous carbon grains are responsible for the 8.8-micron feature. The transition objects show large spectral variations from source to source. This contrasts with C-rich PNs, which all show very similar IR spectra dominated by PAHs. These spectral variations between transition objects of similar effective temperatures cannot be due to excitation variations but imply compositional variations of the dust. Moreover, this result suggests that circumstellar dust evolves during the transition phase from red giant to PN, perhaps as a result of grain-grain collisions and shattering in the fast winds.

Buss, R. H., Jr.↗

DOE OSTI2024

Impact of Iron Species Dispersion on Fe/ZSM–5 Catalyst Performance for Methane Dehydroaromatization (MDA)

Methane dehydroaromatization (MDA) is one of the most promising technologies for directly transforming methane into aromatics. Unlike the extensively investigated Mo/ZSM-5 catalysts, the structure and, consequently, the catalytic activity of Fe/ZSM-5 are markedly influenced by the method of preparation, as shown here. In this study, we prepared 2 % and 4 % Fe/ZSM-5 catalysts via wet impregnation (WI) and incipient wetness impregnation (IWI). Characterizations (XRD, STEM, UV-Vis, NH 3 -TPD and H 2 -TPR) reveal that 2 %Fe-WI mainly possesses isolated or low-polymerized Fe species within zeolite channels, leading to a rapid activation and a higher benzene yield due to the faster reduction to iron suboxides under MDA conditions. In contrast, 2 %Fe-IWI contains bulk iron oxide aggregates, resulting in a slower activation as these aggregates transform into iron carbide through successive reduction and carbonization. Here, a deactivation kinetic study applied to the 2 % catalysts further demonstrates the quantitative relation between Fe site isolation and catalytic activity. Although both 4 % catalysts inevitably form sizable iron oxide clusters and particles due to the high Fe/Al ratio, similar trends are noted, with the WI catalysts exhibiting a shorter induction/activation period and a higher yield of benzene, paralleling observations made with 2 % catalysts.

03 NATURAL GAS↗

NASA NTRS1980

Properties of clusters in the gas phase. V - Complexes of neutral molecules onto negative ions

Ion-molecules association reactions of the form A(-)(B)n-1 + B = A(-)(B)n were studied over a range of temperatures in the gas phase using high pressure mass spectrometry. Enthalpy and entropy changes were determined for the stepwise clustering reactions of (1) sulfur dioxide onto Cl(-), I(-), and NO2(-) with n ranging from one to three or four, and onto SO2(-) and SO3(-) with n equal to one; and (2) carbon dioxide onto Cl(-), I(-), NO2(-), CO3(-), and SO3(-) with n equal to one. From these data and earlier hydration results, the order of the magnitude of the enthalpy changes on the association of the first neutral for a series of negative ions was found to parallel the gas-phase basicity of those anions.

Keesee, R. G.↗

NASA NTRS1980

Carbon-fiber technology

The state of the art of PAN based carbon fiber manufacture and the science of fiber behavior is surveyed. A review is given of the stabilization by oxidation and the subsequent carbonization of fibers, of the apparent structure of fibers deduced from scanning electron microscopy, from X-ray scattering, and from similarities with soft carbons, and of the known relations between fiber properties and heat treatment temperature. A simplified model is invoked to explain the electrical properties of fibers and recent quantum chemical calculations on atomic clusters are used to elucidate some aspects of fiber conductivity. Some effects of intercalation and oxidative modification of finished fibers are summarized.

Hansen, C. F.↗