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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Defining an industrial heat pump: A review & synthesis

Clear and understandable definitions of advanced energy technologies are not common and often confuse those who are not experts. This review paper addresses a critical issue in the field of heat pumps: the ambiguity surrounding the term “industrial heat pump.” The term, as discussed in various literature and media, often leads to misconceptions about the capabilities and applications of heat pumps, particularly in industrial contexts. This review paper seeks to refine and unify the definition of industrial heat pumps by analyzing existing academic and commercial literature, industry reports, and classifications. Unique identifiers explored for the definition of an industrial heat pump include the use of waste heat, operating temperature ranges, size specifications, and specific end-use applications. The study reveals differences in how industrial heat pumps are defined in academic and commercial contexts, highlighting the need for a standardized definition to facilitate better communication among manufacturers, policymakers, and end users. This is especially important considering recent legislative efforts such as the HEAT Act, which seeks to promote industrial heat pump adoption. The proposed definition aims to provide clarity while supporting the effective deployment of industrial heat pumps. With proper adoption, the definition will help promote the role of industrial heat pumps in achieving energy efficiency goals in the industrial sector. The intended impact is for the definition to serve as a foundational reference for future research and policy development.

Heat pump characteristics↗
DOE OSTI2020

Hydraulic fracturing to enhance injectivity and storage capacity of CO 2 storage reservoirs: Benefits and risks

Several potential CO 2 storage reservoirs have been found to have insufficient porosity and permeability to support cost effective commercial-scale injection. As a result, the use of hydraulic fracturing to enhance injectivity and storage capacity of CO 2 storage reservoirs was explored. Previous modeling studies indicate that fracturing can increase storage capacity by modest to significant amounts (10%–35%), depending on model assumptions. Simulations completed as part of this study confirm that for a range of horizontal well lengths, number of fractures, fracture geometries, and fracture properties, injectivity is improved and capacity increases by 13%–71% over the base case unfractured vertical well. Intuitively, increasing the well length and number of fractures had a corresponding impact on increased capacity. Here, fracture area (i.e., the fracture height multiplied by its width) was an important parameter for increasing capacity but the specific geometry (e.g., the ratio of height-to-width) was unimportant. The most important aspect that affected capacity was the ability of a fracture to connect high permeability horizontal zones in the reservoir. This would allow a single well to access both layers, thereby maximizing total storage capacity of the reservoir while likely leading to an overall increase of the CO 2 footprint, which is an important consideration for Class VI UIC permitting. The results of this work demonstrate that hydraulic fracturing is an attractive option to consider when faced with an underperforming geologic carbon storage site that is at risk of causing a project to fail.

03 NATURAL GAS↗
DOE OSTI2021

Utilizing bimetallic catalysts to mitigate coke formation in dry reforming of methane

We report dry reforming of methane (DRM) involves the conversion of carbon dioxide (CO 2 ) and methane (CH 4 ) into syngas (a mixture of hydrogen, H 2 , and carbon monoxide, CO), which can then be used to produce a wide range of products by means of Fischer-Tropsch synthesis. DRM has gained much attention as a means of mitigating damage from anthropogenic greenhouse gas (GHGs) emissions to the environment and instead utilizing these gases as precursors for value-added chemicals or to synthesize sustainable fuels and chemicals. Carbon deposition or coke formation, a primary cause of catalyst deactivation, has proven to be a major challenge in the development of DRM catalysts. The use of nickel- and cobalt-based catalysts has been extensively explored for DRM for their high activity and low cost but suffer from poor stability due to coke formation that has hindered their commercialization. Numerous articles have reviewed the various aspects of catalyst deactivation and strategies for mitigation, but few has focused on the benefit of bimetallic catalysts for mitigating coke formation. Bimetallic catalysts, often improve the catalytic stability over their monometallic counterparts due to synergistic effects resulting from two metal-to-metal interactions. This review will cover DRM literature for various bimetallic catalyst systems, including the effect of supports and promoters, on the mitigation of carbonaceous deactivation

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Preparation and characterization of Cu-Ga-Se thin films synthesized by electrodeposition: Effect of complexing agent and supporting electrolyte

CuGaSe2 (CGS) is a semiconductor that has potential use as a photo electrode for solar water splitting. Its wide band gap and high absorption coefficient make it an ideal candidate for the top absorber in tandem structures. CGS can be synthesized by several techniques, being electrodeposition the most advantageous from a technical standpoint. Many reports show that electrodeposition of these films for producing the desired precursor atomic composition can be aided by using a complexing agent. However, the use of supporting electrolyte and the type of the electrolyte to improve the atomic composition in the films has never been reported. Using cyclic voltammetry, with complexing agents and deposition potentials between -0.5 and -0.9 V vs. Ag/AgCl reference electrode atomic ratios close to the ideal values ([Cu]/[Ga] = 1 and [Se]/[Cu + Ga] = 1), based on atomic composition and morphology analysis are reported in this work. From the X-ray diffraction (XRD), the as-deposited films exhibit poor crystallinity; however, the XRD patterns evidence the formation CuGaSe2 after annealing of the samples.

14 SOLAR ENERGY↗
DOE OSTI2024

Automating the detection of hydrological barriers and fragmentation in wetlands using deep learning and InSAR

The loss of hydrological connectivity and fragmentation of natural wetlands is a widespread driver of wetland degradation. Understanding where and how natural connectivity is impaired is essential for managing, protecting and remediating these ecosystems. Wetland Interferometric Synthetic Aperture Radar (Wetland InSAR) can provide information on surface flow orientation in wetlands at a high spatial resolution, which can be used for barrier detection. However, the broad application of this approach is constrained by the labour-intensive manual delineation of barriers based on mapped water levels. This study presents the first deep learning-based methodology for the automated detection of hydrological barriers. We trained a deep convolutional network to segment edge features of hydrological barriers in 25 image pairs captured by ALOS PALSAR-1 L-Band InSAR between 2006 and 2011. The training dataset consists of manually labelled and delineated barriers showing abrupt changes in water surface elevation and wrapped interferograms with high coherence. We tested this method across three wetland sites: the Everglades and southern Louisiana wetlands (United States) and the Cienaga de Zapata (Cuba). Across these sites, the convolutional network detected hydrological barriers with up to 84% accuracy. The model performed particularly well for linear hydrological barriers such as roads, dikes, and channels. Notably, some barriers impede flow only seasonally, appearing during low water levels and disappearing when water levels rise. Our automated approach to detecting and assessing wetland hydrologic connectivity can be applied more broadly to support the effective management of fragmented wetland ecosystems.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Atomically Dispersed Metals on Well-Defined Supports including Zeolites and Metal–Organic Frameworks: Structure, Bonding, Reactivity, and Catalysis

When metals in supported catalysts are atomically dispersed, they are usually cationic and bonded chemically to supports. Investigations of noble metals in this class are growing rapidly, leading to discoveries of catalysts with new properties. Characterization of these materials is challenging because the metal atoms reside on surfaces that are typically nonuniform in composition and structure. We posit that understanding of structures and catalytic properties of these materials is emerging most strongly from investigations of structurally uniform catalysts (metal atoms dispersed on crystalline supports) which can be characterized incisively with atomic-resolution electron microscopy, X-ray absorption spectroscopy, and infrared spectroscopy, bolstered by density functional theory. We assess the literature of such catalysts supported on zeotype materials, metal–organic frameworks, and covalent organic frameworks. Finally, assessing characterization, reactivity, and catalytic performance of catalysts for oxidation, hydrogenation, the water–gas shift reaction, and others, we consider metal–support interactions and ligand effects for various metal–support combinations, evaluating the degree of structural uniformity of exemplary catalysts and summarizing structure–reactivity and structure–catalytic property relationships.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Ni/CeO 2 Nanocatalysts with Optimized CeO 2 Support Morphologies for CH 4 Oxidation

Catalytic oxidation of CH 4 over nonprecious Ni/CeO 2 catalysts has attracted wide attention. Controlling the morphology of a CeO 2 support can enhance the CH 4 oxidation activity without changing the catalyst composition. Here, in this paper, a series of 2 wt % Ni/CeO 2 nanocatalysts with different CeO 2 support morphologies (nanoparticles (P), rods (R), cubes (C)) and synthetic procedures (precipitation, sol-gel (SG)) were evaluated for their CH 4 oxidation performance. The redox properties of CeO 2 supports and corresponding Ni loaded catalysts were characterized by H 2 -temperature-programmed reduction and oxygen storage capacity (OSC) measurements. The relationship among the CeO 2 morphologies, surface areas, redox properties, and CH4 oxidation activity for both CeO 2 supports and Ni/CeO 2 catalysts was established. The findings suggest that CeO 2 -R has a greater amount of surface oxygen vacancies as well as an improved OSC and CH4 oxidation activity compared to CeO 2 -P and CeO 2 -C supports. The same CH 4 oxidation activity pattern was observed for the Ni containing catalysts (Ni/CeO 2 -R > Ni/CeO 2 -P > Ni/CeO 2 -C). Increasing the CeO 2 surface area by using a sol-gel synthesis method (CeO 2 -SG) improved the amount of surface oxygen vacancies and CH 4 oxidation performance of CeO 2 -SG and Ni/CeO 2 -SG compared to CeO 2 -R and Ni/CeO 2 -R, respectively. Finally, all studied Ni/CeO 2 nanocatalysts showed improved hydrothermal stability compared to conventional Pd/Al 2 O 3 .

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

Cerium(IV) Enhances the Catalytic Oxidation Activity of Single-Site Cu Active Sites in MOFs

The rates of catalytic oxidation of cyclohexane and CO are four and twenty times higher, respectively, with Cu supported on a cerium-based MOF than on the structurally analogous zirconium material. Both Ce- and Zr-based copper catalysts feature uncommon threecoordinate CuII sites bearing different nuclearities, as observed by Cu K-edge extended X-ray absorption fine structure analysis. These findings offer molecular-level understanding of the metal-support interface in MOF catalysts and establish correlations with the more established literature on zirconia and ceria-supported heterogeneous catalysis.

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

CO 2 Methanation on Cu-Cluster Decorated Zirconia Supports with Different Morphology: A Combined Experimental In Situ GIXANES/GISAXS, Ex Situ XPS and Theoretical DFT Study

We report that subnanometer copper tetramer-zirconia catalysts turn out to be highly efficient for CO 2 hydrogenation and its conversion to methane. The cluster size and substrate morphology are controlled to optimize the catalytic performance. The two types of zirconia supports investigated are prepared by atomic layer deposition (~ 3 nm thick film) and supersonic cluster beam deposition (nanostructured film, ~ 100 nm thick). The substrate plays a crucial role in determining the activity of the catalyst as well as its cyclability over repeated thermal ramps. A temperature-programmed reaction combined with in situ X-ray characterization reveals the correlation between the evolution in the oxidation state and catalytic activity. Ex situ photoelectron spectroscopy indicates Cu clusters with stronger interactions with the nanostructured film, which can be the cause for the higher activity of this catalyst. Density functional theory calculations based on the Cu 4 O 2 cluster supported on a ZrOx subunit reveal low activation barriers and provide mechanism for CO 2 hydrogenation and its conversion to methane. Altogether, the results show a new way to tune the catalytic activity of CO 2 hydrogenation catalysts through controlling the morphology of the support at the nanoscale.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Size-Dependent Energy and Adhesion of Pd Nanoparticles on Graphene on Ni(111) by Pd Vapor Adsorption Calorimetry

Carbon-supported late transition-metal nanoparticles are promising catalysts and electrocatalysts for wide-ranging applications. However, experimental investigations of the bonding energetics of metal nanoparticles on carbon supports are very limited. Here, in this work, we report heats of adsorption of Pd vapor deposited onto single-layer graphene(0001) supported on Ni(111) at 100 and 300 K as Pd grows particles of well-defined size in the range from three atom clusters to 6 nm diameter. Sizes were determined from He + low-energy ion scattering (LEIS). In this size range, the differential heat of Pd adsorption increases from 228 kJ/mol to within 10 kJ/mol of the heat of sublimation of bulk Pd (377 kJ/mol). The chemical potential of metal atoms in these nanoparticles as a function of average particle size was determined from these results. The adhesion energy at the Pd/graphene(0001)/Ni(111) interface was extracted from these data and found to be 3.5 J/m 2 for the largest Pd particles. For the three metal elements that have now been studied (Pd, Ni, and Ag), we found an increase in metal/graphene(0001)/Ni(111) adhesion energy with metal carbophilicity, which we defined here as the heat of C atom adsorption on that metal’s (111) surface estimated from published density functional theory calculations.

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

Predicting Adhesion Energies of Metal Nanoparticles to Support Surfaces, Which Determines Metal Chemical Potential versus Particle Size and Thus Catalyst Performance

Improved catalysts and electrocatalysts composed of transition metal nanoparticles dispersed on high-area supports are essential for energy and environmental technologies. The chemical potential of the metal atoms in these supported nanoparticles is an important descriptor that correlates with both their catalytic activity and deactivation rate. This descriptor (μ M ) is predictably determined by the particle size and the adhesion energy per unit area at the metal/support interface (E adh ). We show here that the adhesion energies for different metals on a given support scale linearly with a simple property of the metal: for oxides, it is proportional to the metal oxophilicity, and for the carbon support, it increases linearly with metal carbophilicity (both divided by the area per metal atom). Furthermore, these relationships allow predicting E adh for other metal/support combinations, thus allowing estimation of μ M versus particle size and thereby better structure-based predictions of catalysts’ performance, which can aid in designing improved catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Synthesis Gas Conversion over Rh-Mn-W x C/SiO 2 Catalysts Prepared by Atomic Layer Deposition

The catalytic conversion of synthesis gas to value-added oxygenates and light hydrocarbons was studied here on Rh and Rh–Mn clusters on tungsten carbide-overcoated silica (W x C/SiO 2 ) at 523 K, 580 psi, and CO/H 2 = 1/1. The W x C-modified SiO 2 support was prepared by the overcoating of WO x on SiO 2 using atomic layer deposition (ALD) followed by carburization. The reactivities of Rh/W x C/SiO 2 catalysts with varying number of ALD cycles (number of cycles = 2, 5, 10, 20, and 30) were measured and showed that 5 ALD cycles of WxC suppressed the formation of methane. All W x C-modified catalysts showed enhancement in selectivity toward methanol and ethanol through CO hydrogenation and acetaldehyde hydrogenation, respectively. These catalysts also improved the overall turnover frequency (TOF). The addition of Mn species further promoted the activity and the selectivity toward ethanol and C 2+ hydrocarbons, especially light alkenes. The best performing Rh-2Mn/5cycle-W x C/SiO 2 catalyst (Rh:Mn molar ratio = 1:2) achieved 84.7% selectivity toward valuable oxygenates and C 2+ hydrocarbons with a ratio of alkenes to alkanes equal to 1.7, compared to Rh/SiO 2 which exhibited 80.4% selectivity toward the products aforementioned with a ratio of 0.5. The overall TOF was 20 times higher than that over Rh/SiO 2 (i.e., 5.6 × 10 –2 s –1 vs 2.9 × 10 –3 s –1 ). X-ray diffraction revealed that the existence of W 2 C, which was the dominant phase in Rh/5cycle-W x C/SiO 2 , favored the suppression of methane and enhanced the production of alcohols and C 2+ hydrocarbons compared to the WC support. Density functional theory calculations for Rh 19 , Rh 31 , and Rh 37 clusters on various WC surfaces suggested that the shape of Rh clusters is condition dependent and subject to H 2 pressure. The C- and O- binding energies on various sites for the clusters were used with scaling relations to probe their catalytic activity. With the use of this approach, the increase in the O binding energy when moving from the SiO 2 -supported Rh 37 cluster to the WC-supported cluster leads to an increase in the activity of Rh/W x C/SiO 2 at the expense of the reduction in the number of sites that are selective toward C 2 oxygenates.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Impact of Urbanization on Convection, Lightning, and Precipitation Over the Houston Metropolitan Area: Case Study Simulation From the TRACER Campaign

This study investigates the effects of urbanization, specifically land use change and anthropogenic emissions (AE), on convection, lightning, and surface precipitation for a case of summertime sea‐breeze convection observed over the Houston metropolitan area. The unique capabilities of the NASA‐Unified Weather Research and Forecasting model allows us to conduct a series of sensitivity experiments with complex configurations, in particular including multi‐year land model spin‐up simulations, treatment of aerosols and their precursors, and explicit cloud charging and lightning. The simulation results show that urban land use primarily alters the temporal evolution of convection, lightning, and surface precipitation, leading to late afternoon thunderstorm development. The decrease in latent heat flux from the land surface caused by urbanization weakens convection in the early afternoon, while a condition suitable for convection development is maintained in the late afternoon due to less stabilization of the lower troposphere by the weaker convection development and high sensible heat flux from the surface. On the other hand, anthropogenic aerosols directly enhance convection, lightning, and surface precipitation by increasing convective updrafts due to the aerosol‐induced convective invigoration. The combined effects of urban land use and AE lead to even stronger thunderstorms in the late afternoon, mostly consistent with observations. These results indicate that urbanization increases the probability of late afternoon thunderstorms over the Houston area during the summer season. Advanced weather forecasting models that incorporate these urbanization effects might support sustainable urban planning to better mitigate the impacts of urbanization on local weather and public safety.

Iguchi, T. [Univ. of Maryland, College Park, MD (U↗
DOE OSTI2021

Ferroelectric phase-transition frustration near a tricritical composition point

Phase transition describes a mutational behavior of matter states at a critical transition temperature or external field. Despite the phase-transition orders are well sorted by classic thermodynamic theory, ambiguous situations interposed between the first- and second-order transitions were exposed one after another. Here, we report discovery of phase-transition frustration near a tricritical composition point in ferroelectric Pb(Zr 1-x Ti x )O 3 . Our multi-scale transmission electron microscopy characterization reveals a number of geometrically frustrated microstructure features such as self-assembled hierarchical domain structure, degeneracy of mesoscale domain tetragonality and decoupled polarization-strain relationship. Associated with deviation from the classic mean-field theory, dielectric critical exponent anomalies and temperature dependent birefringence data unveil that the frustrated transition order stems from intricate competition of short-range polar orders and their decoupling to long-range lattice deformation. With supports from effective Hamiltonian Monte Carlo simulations, our findings point out a potentially universal mechanism to comprehend the abnormal critical phenomena occurring in phase-transition materials.

42 ENGINEERING↗
DOE OSTI2018

Catalytic Oxidation of Propane over Palladium Alloyed with Gold: An Assessment of the Chemical and Intermediate Species

Understanding the catalytic oxidation of propane is important for developing catalysts not only for catalytic oxidation of hydrocarbons in emission systems but also for selective oxidation in the chemical processing industry. For palladium-based catalysts, little is known about the identification of the chemical or intermediate species involved in propane oxidation. We describe herein findings of an investigation of the catalytic oxidation of propane over supported palladium nanoalloys with different compositions of gold (Pd n Au 100–n ), focusing on probing the chemical or intermediate species on the catalysts in correlation with the bimetallic composition and the alloying phase structure. In addition to an enhanced catalytic activity, a strong dependence of the catalytic activity on the bimetallic composition was revealed, displaying an activity maximum at a Pd : Au ratio of 50 : 50 in terms of reaction temperature. This dependence is also reflected by its dependence on the thermochemical treatment conditions. While the activity for nanoalloys with n ~ 50 showed little change after the thermochemical treatment under oxygen, the activities for nanoalloys with n < 50 and n > 50 showed opposite trends. Importantly, this catalytic synergy is linked to the subtle differences of chemical and intermediate species which have been identified for the catalysts with different bimetallic compositions by in situ measurements using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). For the catalytic oxidation of propane over the highly-active catalyst with a Pd : Au ratio of 50 : 50, the major species identified include acetate and bicarbonate, showing subtle differences in comparison with the identification of bicarbonate and formate for the catalyst with <50% Au (with a lower activity) and the absence of apparent species for the catalyst with >50% Au (activity is largely absent). The alloying of 50% Au in Pd is believed to increase the oxophilicity of Pd, which facilitates the first carbon–carbon bond cleavage and oxygenation of propane. Finally, the implications of the findings on the catalytic synergy of Pd alloyed with Au and the design of active Pd alloy catalysts are also discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

High-throughput oxygen chemical potential engineering of perovskite oxides for chemical looping applications

Chemical looping (CL) represents a versatile, emerging strategy for sustainable chemical and energy conversion. Designing metal oxide oxygen carriers with suitable redox properties remains one of the most critical challenges to CL due to the considerably different thermodynamic property requirements for different applications. Here, taking SrFeO 3–δ as a base-structure, this study seeks to rationally substitute its A- and/or B-site cations to tailor the equilibrium oxygen partial pressure over 20 orders of magnitude. 2401 Sr x A 1–x Fe y B 1–y O 3–δ perovskite-phase structures were investigated using high-throughput density functional theory (DFT) and 227, 273 high-entropy perovskites were screened via machine learning (ML). This significantly expands the materials design space. While most of the compositions predicted are new and nonobvious, 19 previously reported oxygen carriers, with excellent redox properties, were correctly identified by the algorithm. Moreover, we experimentally demonstrated 15 new oxygen carriers with superior redox performance. These results support the effectiveness of the high-throughput approaches for accelerated materials discovery.

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

Assessing DER Network Cybersecurity Defences in a Power-Communication Co-Simulation Environment

Increasing penetrations of interoperable distributed energy resources (DER) in the electric power system are expanding the power system attack surface. Maloperation or malicious control of DER equipment can now cause substantial disturbances to grid operations. Fortunately, many options exist to defend and limit adversary impact on these newly-created DER communication networks, which typically traverse the public internet. However, implementing these security features will increase communication latency, thereby adversely impacting real-time DER grid support service effectiveness. In this work, a collection of software tools called SCEPTRE were used to create a co-simulation environment where SunSpec-compliant PV inverters were deployed as virtual machines and interconnected to simulated communication network equipment. Network segmentation, encryption, and moving target defence security features were deployed on the control network to evaluate their influence on cybersecurity metrics and power system performance. The results indicated that adding these security features did not impact DER-based grid control systems but improved the cybersecurity posture of the network when implemented appropriately.

97 MATHEMATICS AND COMPUTING↗