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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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At least 1,423 records · Page 79
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Oxidation kinetic modelling of Fe-based oxygen carriers for chemical looping applications: Impact of the topochemical effect

Chemical looping is a promising technology for fossil fuel utilization due to its high fuel conversion efficiency with in-situ CO 2 capture capability. Metal oxide are used as oxygen carriers (OCs) and circulate between a fuel reactor and an air reactor to perform reduction and oxidation reactions, respectively. In general, OC exiting the fuel reactor is not reduced fully to its metallic state due to many factors including carbon deposition and OC deactivation. Therefore, the effect of the initial reduction state on the OC oxidation in the air reactor is a significant parameter for consideration in developing the oxidation kinetic model. The objective of this work is to develop a physically significant kinetic model that applies to the oxidation of both initially fully and partially reduced OC with air. For this study, 1.5 mm Fe-based OC particle supported with TiO 2 was used as the model OC particle due to its complex multistep reaction nature. The oxidation kinetics were experimentally investigated in a thermogravimetric analyzer (TGA). Results indicate a significant difference in the oxidation rate profile for the OCs when oxidized from an initially fully reduced compared to an initially partially reduced state. Elemental mapping via energy-dispersive X-ray spectroscopy (EDS) reveals a shrinking-core type topochemical pattern across the OC particle, which was identified to be the cause of the dependency of kinetics on the initial reduction state. A generalized kinetic model was developed based on the observed shrinking-core behavior without presuming any rate-determining steps and experimentally validated over a broad range of temperatures (800–1000 °C) and oxygen concentrations (5, 7, 10, and 15 mol%). Impacts of particle porosity, size, and core-shell structure on the OC oxidation kinetics were analyzed in the developed oxidation kinetic model to suggest methods of improving the oxidation rate of the OC without modifying the chemical composition.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

The impact of wind, solar, and other factors on the decline in wholesale power prices in the United States

Across multiple organized wholesale power markets in the United States, annual average prices declined by 19–64 dollars per MWh between 2008 and 2017 while retirements of thermal power plants accelerated. Several prominent changes over the last decade are often discussed as contributors to this decline in prices. These include growth in wind and solar, a reduction in the price of natural gas, and weakened load growth. Here we construct a fundamental supply curve model for each of seven organized wholesale market regions and use counterfactual simulations to assess the degree to which wind and solar—among other factors—have influenced wholesale electricity prices. We find that growth in wind and solar since 2008 reduced average annual wholesale electricity prices by less than 3 dollars per MWh. In contrast the decline in natural gas prices reduced wholesale prices by 7–53 dollars per MWh, depending on the region. This suggests that recent thermal-plant retirements in the U.S. are primarily due to low natural gas prices, not growth in wind and solar. Fully isolating the impact of individual factors, however, is limited by non-linear interactions between factors.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

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↗
DOE OSTI2023

Assessing the Impact of Cybersecurity Attacks on Energy Systems

This paper investigates the cyber resiliency of future power systems with high penetration of distributed energy resources using advanced distributed and (or) hierarchical control architectures. Specifically, we simulate cyberattacks on three prototypical use cases, and we identify attack scenarios that are the most damaging to the overall system performance. We show that these attacks can have a significant impact on grid operation. Results provide additional insights into the robustness of the system to the most common cyberattacks.

buildings↗
DOE OSTI2023

Impacts of PTL coating gaps on cell performance for PEM water electrolyzer

The anode porous transport layer (PTL) is a critical component of polymer electrolyte membrane (PEM) water electrolyzers, providing electrical conduction and water/oxygen transport to the anode catalyst layer. Platinum group metal (PGM) coatings are applied to titanium PTLs to prevent oxidation and preserve conductivity. To implement PEM water electrolysis on a large scale, it is essential to minimize the cost of mass-manufactured cell components while ensuring that defects in materials and components do not adversely affect the performance of the cell. In this study, we created gaps in the Pt coatings that are typically applied to PTLs to understand their effects on cell performance and inform on fabrication tolerances. The PTL coatings were fabricated by sputter deposition of Pt, intentionally leaving uncoated regions in either large patches or thin strips. For either geometry, the cell performance decreased with the increasing fraction of the uncoated regions. However, PTLs containing multiple thin uncoated strips caused a less severe performance effect than PTLs with continuous uncoated regions of the same relative total area. Through analysis of cell performance, impedance, and 3D charge transport modelling, here we demonstrate that both the anode catalyst layer and membrane play a role in distributing current to mitigate the impact of coating defects at a short length scale. These results allow to draw conclusions about the tolerance requirements with regards to PTL coating uniformity in terms of both the size and total area of defects.

08 HYDROGEN↗
DOE OSTI2022

Impact of the mid-latitude zonal circulation on dynamic mechanism of anomalous precipitation over China in summer 2021

China was hit by extreme precipitation in July and August of 2021 along with significant monthly variation. The positive precipitation anomalies observed in July were mainly located in eastern China, but these anomalies shifted to the middle and lower reaches of the Yangtze River (MLYR) in August. In this study, we investigated the July and August precipitation anomaly dynamics based on the three-pattern decomposition of global atmospheric circulation (3P-DGAC) method. The results showed that the mid-latitude zonal circulation played a dominant role in July 2021, causing anomalous positive relative vorticity advection over the center of the positive precipitation anomalies, thus providing strong convective activity for the anomalous precipitation. Nevertheless, the August anomalies could be better explained from a climate perspective. The anomalous relative vorticity distribution patterns recorded in August were often accompanied by extreme precipitation in the MLYR, and the negative relative vorticity anomalies identified in Northeast Asia also played a crucial role. In conclusion, the mechanisms of precipitation anomalies in July and August 2021 were almost completely disparate. In this study, we emphasized the role of the mid-latitude zonal circulation in extreme precipitation events, and suggested that the impact of mid-latitude zonal circulation will be further accentuated under global warming.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Exploring the impact of surface topography on Rayleigh-Bénard dry convection in the Pi cloud chamber using OpenFOAM: In cylindrical and rectangular geometries

The Pi convection-cloud chamber can generate steady-state turbulence in both rectangular and cylindrical shapes via Rayleigh-Bénard convection (RBC) by maintaining warm bottom and cold top surfaces. Although most experiments in the Pi chamber were conducted in cylindrical shapes, all previous Pi chamber simulations were conducted in a rectangular shape due to the limitations of those models to discretize a cylindrical domain when using the finite difference method therein. Here, we use OpenFOAM, an open-source finite-volume-based Computational Fluid Dynamics (CFD) software package, to conduct Large-Eddy Simulation (LES) of dry RBC in the Pi chamber at high Rayleigh numbers (10 8 to 10 9 ). Results show that large-scale circulation (LSC) direction varies in the chamber with a constant side wall temperature. Imposing a slight temperature imbalance at the side wall ranging from 0.1 to 0.7 degrees can lock the LSC, aligning better with Pi chamber observations, particularly at higher Rayleigh numbers. In addition, we examine the impact of surface topography on LSC and heat transfer in RBC systems within cylindrical and rectangular shapes under varying conditions. Results show that roughing top/bottom surfaces by adding bars of a few tens millimeters height can strengthen thermal plumes and enhance temperature fluctuations in the chamber. Furthermore, we observe that different bar height configurations lead to notable changes in LSC orientation and thermal stratification, highlighting the complex interactions between surface features and convection patterns. This finding highlights how surface topography and chamber geometry affect Rayleigh-Bénard convection, improving understanding of turbulent heat transfer and atmospheric boundary-layer processes. Direct Numerical Simulations (DNS) are also conducted to validate LES results. In conclusion, while LES effectively captures qualitative behaviors seen in DNS, it tends to underestimate velocity variances near walls, illustrating a trade-off between computational efficiency and accuracy.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Feedstock and Catalyst Impact on Bio-Oil Production and FCC Co-Processing to Fuels

NREL's thermochemical biomass conversion research is focused on ex-situ upgrading of biomass fast-pyrolysis (FP) vapors as an efficient route to completely biogenic pyrolysis-based fuel precursors, fuels, and value-added chemicals depending on catalyst and process conditions. A near term pathway being developed uses these liquids for co-processing with petroleum feedstocks to assess biogenic carbon incorporation in hydrocarbon fuel feedstocks for potential refinery use. In this work, the impact of feedstock and catalyst on catalytic fast pyrolysis oil (CFPO) composition was determined with the oils then assessed for biogenic fuel production via FCC (fluidized catalytic cracking) co-processing. Biomass vapors were generated via fast pyrolysis with destabilizing vapor components (char, inorganics, tar aerosols) removed by hot gas filtration to produce clean vapors more responsive to catalytic upgrading. A Davison Circulating Riser (DCR), a petroleum industry standard for fluidized catalytic cracking (FCC) catalyst evaluation, was coupled to a custom pyrolyzer system designed to produce consistent-composition pyrolysis vapors as feed to the DCR. Pyrolysis vapors, derived from pure hardwood and softwood, were upgraded using commercially available modified zeolite-based catalysts to produce CFPOs. These upgraded oils were analyzed via 31P and 13C NMR spectroscopy, GCxGC-TOF/MS, carbonyl and ultimate analysis (CHNO), and simulated distillation (SIMDIS) to assess both oil chemistry and distillation behavior as they relate to catalyst and feedstock type for producing fungible hydrocarbon product liquids. These exploratory vapor-phase-upgrading results demonstrated the feasibility of producing refinery-compatible hydrocarbon fuel intermediates entirely from biomass-derived fast-pyrolysis vapors using an industry-accepted DCR system for catalytic upgrading. The FCC co-processing results demonstrated the feasibility of using CFPOs with VGO feeds in FCC refinery operations to produce biogenic carbon containing fuels.

biogenic carbon↗
DOE OSTI2024

Policy impact on economic and environmental sustainability of anaerobic digestion: Industrial case study Insights

This paper thoroughly examines how policy incentives impact the economic and environmental sustainability of anaerobic digestion (AD) systems. It uses techno-economic and life cycle analyses, along with real industry data, to explore the entire AD process—from feedstock acceptance to digestate disposal. It evaluates the effects of various U.S. policy crediting programs on the economic viability of different AD pathways for treating sewage sludge and food waste. Furthermore, tipping fees are identified as the primary driver of profitability, while policy credits play a crucial role in enhancing economic feasibility, particularly for renewable natural gas production. However, future regulatory changes could reshape this economic landscape. All AD pathways are found to significantly reduce greenhouse gas emissions, though economic outcomes are highly sensitive to digestate disposal costs and feedstock tipping fees. Co-digestion with food waste is proposed as a strategy to reduce dependence on policy credits and improve long-term economic stability.

Anaerobic Digestion↗
DOE OSTI2024

Long-term impact of electrification and retrofits of the U.S residential building in diverse locations

The U.S. buildings sector contributes 30% of operational carbon emissions, with residential buildings accounting for 56%. Reducing residential carbon emissions is crucial for achieving net-zero carbon goal. While many studies examine energy efficiency retrofit (EER) and electrification, few explore their long-term impacts across diverse climates and dynamic grid clean energy penetrations, as well as their economic effects on households. Here, this study proposes a method to assess how EER and electrification affect long-term decarbonization and economics across different climates, focusing on carbon emissions, energy burden (the percentage of household income spent on energy), and payback period in four locations: Tampa, San Diego, Denver, and Great Falls. The study also introduces the concept of implicit energy burden by considering investment costs. Results show that while electrification can reduce long-term emissions with increased clean energy penetration, it may not always achieve decarbonization due to mismatches between clean energy availability and demand. In cooling-dominant locations, electrification lowers energy burden and peak demand, but in heating-dominant locations, it increases energy burden to 8.24%, raises peak demand by 632.78%, and shifts it from summer to winter. After integrating investment costs, the implicit energy burden can reach 8.35% in cold climates. For already highly electrified buildings in Denver and Great Falls, the payback period of EER measures can be shortened by up to 48.98%. The study highlights a tradeoff between decarbonization and energy burden alleviation, showing that while EER measures can reduce the energy burden, they only achieve one-quarter of the carbon emission reduction of electrification.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2025

Porosity in nuclear graphite and its impact on nuclear reactor science and criticality safety applications

Porosity in nuclear-grade graphite significantly influences its low-energy neutron scattering, yet its effect on underlying phonon properties remains debated. Here, this work integrates inelastic and small-angle neutron scattering (INS/SANS) experiments, advanced atomistic simulations with a novel machine-learned potential (DeepMD), total cross-section measurements, and neutronics calculations (SCALE, MCNP, OpenMC) to investigate porosity’s impact on neutron thermalization. INS measurements on diverse graphite grades reveal no discernible porosity effect on phonon spectra, which align with crystalline graphite. Conversely, total cross-section data below ≈10 meV show increased scattering attributable to SANS. Our DeepMD simulations demonstrate that realistic micropores do not distort phonon spectra, challenging the assumptions in current ENDF/B-VIII.1 porosity thermal scattering laws (TSLs). These TSLs, based on random atom removal, produce unphysical phonon spectra and inflate inelastic cross-sections. Augmenting a crystalline TSL with an SANS component accurately captures experimental total cross-sections. Neutronics benchmarks (ICSBEP/IRPhE) show ENDF porosity TSLs unphysically increase neutron multiplication factor, keff. Crucially, incorporating SANS physics (NCrystal/OpenMC) indicates accurately modeled porosity negligibly affects keff, reactor physics, or criticality safety.

Critical benchmarks↗
DOE OSTI2020

Enhanced NO, CO and C 3 H 6 conversion on Pt/Pd catalysts: Impact of oxygen storage material and catalyst architecture

Simultaneous conversion of NO, CO and C 3 H 6 under stoichiometric conditions was carried out on washcoated monoliths containing oxygen storage material (OSM)-promoted mixed Platinum group metals (PGM: Pt(95 %)/Pd(5 %)), to evaluate OSM promotion and to identify the best architecture. The studied OSMs include ceria-zirconia (Ce 0.3 Zr 0.7 O 2 ; CZO) and mixed metal oxide spinel (Mn 0.5 Fe 2.5 O 4 ; MFO). PGM supported directly on the OSM was found to be the best design for CZO, leading to a ~70 °C simultaneous decrease in the light-off temperature (T 80 ; feed temperature giving 80 % conversion) for NO, CO and C 3 H 6 conversion compared to the alumina-supported PGM. Close coupling between the PGM and CZO is responsible for the activity promotion. In contrast, a dual-layer architecture (top PGM layer, bottom MFO layer) outperformed the MFO-supported PGM catalyst. The dual-layer PGM-MFO catalyst decreased the T 80 by ~50 °C for NO, CO and C 3 H 6 conversion compared to the PGM-only catalyst. Enhancement obtained with the dual-layer PGM-MFO architecture relies on a direct catalytic contribution from the spinel. During lean/rich modulation the addition of CZO or spinel helps to mitigate the detrimental impact of modulation on NO, CO and C 3 H 6 conversion above 400 °C. The data suggest that both CZO and MFO can buffer lean/rich modulation but exhibit preference to different reductants; CZO-supported PGM and dual-layer PGM-MFO show no conversion decrease during modulation for CO or C 3 H 6 modulation, respectively. Dynamic oxygen storage capacity (DOSC) measurements show that the spinel exhibits ~10 times higher DOSC than CZO for both CO and C 3 H 6 reductants. Both CO and C 3 H 6 are equally effective reductants for the MFO but CO is better for CZO and PGM-deposited CZO. The study provides useful insight into benefits of OSM and provides guidance for optimization of the multi-component PGM + OSM catalyst composition and architecture.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Impact of functional groups on the electrocatalytic hydrogenation of aromatic carbonyls to alcohols

We report that electrocatalytic hydrogenation (ECH) of biomass-derived feedstocks has a critical dependence on the molecular structure of the organic and its adsorption on the electrode surface. In this study, we investigated the role of functional groups in the adsorption of the organic molecule on the charged Pd (111) surface and its subsequent effect on organic reduction in electrochemical hydrogenation of organic molecules. With three aromatic carbonyls of benzaldehyde (BZD), acetophenone (ACE), and vanillin (VAN), we rationalize molecular-scale adsorption and interfacial charge transfer processes by employing density-functional-theory based ab initio molecular dynamics simulations. We observe that the functional group and electrode charge strongly affect the proximity of organic molecule to the Pd (111) surface, where distances of aromatic ring and carbonyl group of the organic on the electrode change distinctively with functional groups and charge state of electrode, which strongly impact reduction of organics on the surface. Calculations of differential electron density show the strongest reduction with benzaldehyde via interfacial electron transfer from the charged Pd surface. We also observe that the interaction between the functional groups and solvent (VAN > BZD > ACE) significantly influence the organic interaction with the charged electrode (BZD > VAN > ACE), resulting in the net interaction energy between the organic and the electrode in the order of BZD > ACE > VAN. Experimental measurement of ECH rate also show the same trend of the net interaction energy. These results demonstrate the significance of solvent effect on the reducibility of organic molecules on electrodes.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Exploring the potential and impact of single-crystal active materials on dry-processed electrodes for high-performance lithium-ion batteries

Roll-to-roll powder-to-film dry processing (DP) and single-crystal (SC) active materials (AMs) with many advantages are two hot topics of lithium-ion batteries (LIBs). However, DP of SC AMs for LIBs is rarely reported. Consequently, the impact of SC AMs on dry-processed LIBs is not well understood. Herein, for the first time, via a set of experimental and theoretical studies of the conventional polycrystalline-AM- and SC-AM-based DPed electrodes (DPEs), this work not only reports a high-performance dry SC-AM cathode for LIB manufacturing, but also establishes some fundamental understanding of SC-based dry-processed electrodes, including their morphology, structure, mechanical strength, electronic conductivity and LIB electrochemical behavior. Further, the results suggest that DP of SC AMs is promising, which can dramatically improve the electrochemical kinetics at electrode level and particle level. Specifically, for the rate capability and long-term cyclability in full cells, SC DPEs exhibit a discharge specific capacity of 152.1 mAh g -1 at 1C and a capacity retention rate of 79.9 % at C/3 over 500 cycles, which are superior to those of PC DPEs (135.6 mAh g -1 and 68.3 %) at the same conditions and are further confirmed by the simulation data from the theoretical modelling study. Therefore, this comprehensive work marks a significant milestone for DP strategy and SC AMs, enlightening future research and development of LIB manufacturing.

25 ENERGY STORAGE↗
DOE OSTI2020

Comprehensive In Vivo Interrogation Reveals Phenotypic Impact of Human Enhancer Variants

Establishing causal links between non-coding variants and human phenotypes is an increasing challenge. In this paper, we introduce a high-throughput mouse reporter assay for assessing the pathogenic potential of human enhancer variants in vivo and examine nearly a thousand variants in an enhancer repeatedly linked to polydactyly. We show that 71% of all rare non-coding variants previously proposed as causal lead to reporter gene expression in a pattern consistent with their pathogenic role. Variants observed to alter enhancer activity were further confirmed to cause polydactyly in knockin mice. We also used combinatorial and single-nucleotide mutagenesis to evaluate the in vivo impact of mutations affecting all positions of the enhancer and identified additional functional substitutions, including potentially pathogenic variants hitherto not observed in humans. Our results uncover the functional consequences of hundreds of mutations in a phenotype-associated enhancer and establish a widely applicable strategy for systematic in vivo evaluation of human enhancer variants.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Cerium oxide impact on fresh and hardened properties of cementitious materials

Cements used in global nuclear waste treatment, storage, and disposal require thorough testing of fresh and cured properties to demonstrate regulatory compliance. Using actual radioactive wastes is often cost-prohibitive during early scoping tests necessitating the use of non-radiological surrogates. Cerium (Ce) is often used as a surrogate for actinides uranium (U) and plutonium (Pu) in spent nuclear fuel, yet few studies have explored how Ce impacts the properties used to qualify a cement for use. Here, this work compares the fresh and cured properties of three classes of cements – ordinary portland cements, ultra-high performance cement composites, and magnesium phosphate cements – each with and without ceria (CeO 2 ). Due to CeO 2 sorption of water (54 vol%) that effectively decreases the water available to hydrate and form binding cement phases, variations in key cement properties were detected that suggest surrogate CeO 2 –cementitious matrices may not be representative of matrix behaviors when using U and Pu sources.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Sorption and oxidation of Co(II) at the surface of birnessite: Impacts of aqueous Mn(II)

The sorption of aqueous Mn(II) (1 mM) and Co(II) (50 and 200 μM) onto hexagonal birnessite (0.1 g L –1 ) was studied under anoxic conditions at pH 6.5 and 7.5 in binary and ternary experiments using batch kinetic experiments and XRD, ATR-FTIR, and Co K-edge EXAFS analyses. In the binary systems, sorption of Co(II) was accompanied by partial oxidation to Co(III) yielding a mixture of corner-sharing Co(II) and edge-sharing Co(III) complexes at both pH values, while Mn(II)-birnessite interaction resulted in coordination of Mn(II/III) at layer vacancy sites at pH 6.5, and led to reductive transformation of birnessite into feitknechtite at pH 7.5. In the ternary systems, strong mutual interferences between Co(II) and Mn(II) co-sorbates reduced the rate and extent of sorption relative to the binary experiments. The introduction of Mn(II) aq into the high-Co systems (200 μM) halted the slow sorption of Co(II) that was attributed to the incorporation of Co(III) into layer vacancies, while Co(II) aq prevented Mn(II)-driven transformation of birnessite into feitknechtite at pH 7.5. In the low-Co system (50 μM), reductive transformation of birnessite by Mn(II) aq at pH 7.5 produced Co(II)-substituted feitknechtite, a conversion that was accompanied by reduction of sorbed Co(III) to Co(II) which was partially released to solution. The strong effects of co-sorption are attributed to the similarity in sorption mechanisms of Co(II) and Mn(II), which both sorb as a mixture of di- and trivalent species. Finally, the results of this work demonstrate that aqueous Mn(II) may significantly affect the reactivity of phyllomanganate sorbents towards dissolved Co(II), and therefore impact the speciation and solubility of this trace metal in anoxic and suboxic geochemical environments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Characterizing the combined impact of nucleation-driven precipitation and secondary passivation on carbon mineralization

The evolution of mineral reactive surface area is one of the primary phenomena controlling the progression and extent of mineral carbonation. The CO 2 mineralization begins with nucleation of crystals that provide initial surface area for subsequent growth of the mineral. However, many reactive transport models (RTMs) for CO 2 mineralization do not include the nucleation process. The few RTMs that do include it are yet to be validated against experimental data. Similarly, many RTMs ignore passivating effects of the secondary mineral, which coats the surface of the dissolving mineral, slow down the reaction process, and reduce the total extent of carbonation. Furthermore, the combined impact of nucleation and passivation on carbon mineralization is yet to be properly characterized. In this study, we consider the coupled effects of passivation and nucleation on the mineralization extent. The nucleation-driven precipitation model relies on the formation of nuclei to provide a surface area for crystal growth, while a new model is proposed to account for passivation effects. Our analysis shows that (i) omission of nucleation leads to overestimation of extent of mineralization, and (ii) omission of passivation leads to overestimation of host rock reactivity. The model was evaluated via comparison with CO 2 mineralization data from the literature and models that ignore these processes. We observed that including nucleation and passivation lead to closer predictions of the CO 2 mineralization extent. Therefore, this study highlights the importance of including the coupled nucleation-driven precipitation and secondary passivation in RTMs. Here, the findings from the study can be applied in various scientific and engineering applications such as petroleum production, cement carbonation, CO 2 sequestration, chemical weathering, and concrete degradation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗