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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 721 records · Page 40
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Estimating the energy requirement for hydrogen production in proton exchange membrane electrolysis cells using rapid operando hydrogen crossover analysis

Hydrogen (H 2 ) crossover in proton exchange membrane water electrolyzers refers to the process by which hydrogen produced at the cathode traverses the membrane and mixes with the oxygen produced at the anode. This phenomenon reduces efficiency and may pose flammability hazards. In this work we present a method for quantifying the H 2 content of the anode exhaust gas using a gas chromatograph that is capable of sampling data every 2 min. Subsequent theory is presented to calculate the crossover flux, overall H 2 efficiency, and H 2 energy requirements. Results the effects of membrane thickness using Nafion TM N117 (178 um) and Nafion TM NR212 (51 um) membranes. Furthermore, it was found that thinner membranes lead to improved VI performance but exhibit higher crossover rates. Despite their increased crossover, leading to decreased hydrogen efficiency, the calculated required energy for NR212 membrane-electrode assemblies (MEAs) was significantly lower than that of N117 MEAs.

08 HYDROGEN↗
DOE OSTI2023

Improved catalytic activity of Mo x Ni y Al z thin films as electrocatalyst for hydrogen evolution reaction in alkaline media

In this work, we report activities of Mo x Ni y X z (where X is Al, Co, Cr, Cu, Fe, W)-based electrocatalysts for hydrogen evolution reaction (HER) in a 1 M NaOH solution. Mo x Ni y X z thin film electrocatslysts were prepared by magentron sputtering at 25°C and 800°C and characterized by scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analyzer and X-ray diffraction (XRD) analysis. Here, the catalytic activity of electrocatalyst was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The electrocatalyst based on Mo 80 Ni 5 Al 15 (800°C) shows the best value of the overpotential (-181 mV) for HER from all tested ternary systems. XRD analysis indicates that HER activity only Mo 80 Ni 5 Al 15 thin films prepared at 800°C contained fcc phase. Other less active composition contained only bcc phase. The results obtained from impedance spectroscopy are consistent with the results from cyclic voltammetry. The stability of the prepared catalyst was studied by chronoamperometric analysis. The results from chronoamperometry show that HER activity of Mo 80 Ni 5 Al 15 prepared at 800°C, after very slight initial activity decrease, stays constant, while activity of Ni catalyst decreased almost twice in measured time window. Since Ni is commonly used industrial catalyst, Mo 80 Ni 5 Al 15 based alloy could be more attractive catalyst material for alkaline electrolyzers.

08 HYDROGEN↗
DOE OSTI2025

Renewable hydrogen horizon: Geospatial techno-economic feasibility and life cycle greenhouse gas analysis in the Middle East and North Africa

Renewable hydrogen is receiving increasing attention for its potential as a flexible energy carrier in sectors such as transportation and industry. Specific cost and carbon intensity (CI) of renewable hydrogen production vary largely based on the location, owing to differences in renewable energy resources, as well as the supply chain dynamics. This study maps the techno-economic and life cycle greenhouse gas emissions of renewable hydrogen production in the Middle East and North Africa region, leveraging abundant solar and wind resources. The work investigates the variability in hydrogen costs and CI, optimally sizing proton-exchange membrane (PEM) electrolyzers to account for partial and cyclic loading, and explores standalone versus grid-connected systems. PEM capacity ratios of 52 %–63 % for photovoltaic (PV) systems and 28 %–82 % for wind systems were identified as optimal, with hydrogen production costs ranging from $\$3.8$-$\$4.8$/kg for PV and $2.0-$7.0/kg for wind. CIs span from 1.9 to 3.7 kg CO 2 ,eq /kg H 2 for PV and 0.4–7.7 kg CO 2,eq /kg H 2 for wind systems. The study highlights significant cost and CI reductions achievable with technological advancements and co-product revenue from oxygen and excess electricity sales.

Carbon Intensity↗
DOE OSTI2025

Solid oxide electrolysis cell and stack testing best practices

Solid oxide electrolyzer (SOE) technology is an emerging method for hydrogen production, noted for its superior electrical efficiency. Despite the significant progress made in recent years, the broad development of SOE technology is often constrained by the necessary and extensive "skill of the craft" required to successfully test simple single cell test articles. This may be linked to the dearth of practical and pragmatic guidance within the literature for safe, reliable, and performant test equipment and test procedures. Researchers at the Idaho National Laboratory (INL) have been actively testing SOEs ranging from button cells to stacks up to 500 kW, in collaboration with industry and other national laboratories. Based on operational experience, INL has developed system design procedures that ensure safe and reliable operation of SOE systems with the level of support required for each test. This paper presents key aspects of SOE stack and system testing, including safe design procedures, balance of plant components design, and specific implementations at INL. Practical design details of reactants, heat, and power management are presented along with lessons learned from the SOE test facility operations at INL.

08 HYDROGEN↗
DOE OSTI2023

CO 2 electroreduction favors carbon isotope 12 C over 13 C and facilitates isotope separation

We discovered that CO 2 electroreduction strongly favors the conversion of the dominant isotope of carbon ( 12 C) and discriminates against the less abundant, stable carbon 13 C isotope. Both absorption of CO 2 in the alkaline electrolyte and CO 2 electrochemical reduction favor the lighter isotopologue. As a result, the stream of unreacted CO 2 leaving the electrolyzer has an increased 13 C content, and the depletion of 13 C in the product is several times greater than that of photosynthesis. Using a natural abundance feed, we demonstrate enriching of the 13 C fraction to ~1.3% (i.e., +18%) in a single-pass reactor and propose a scalable and economically attractive process to yield isotopes of a commercial purity. Our finding opens pathways to both cheaper and less energy-intensive production of stable isotopes ( 13 C, 15 N) essential to the healthcare and chemistry research, and to an economically viable, disruptive application of electrolysis technologies developed in the context of sustainability transition.

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

On the mechanism of the electrochemical conversion of ammonia to dinitrogen on Pt(1 0 0) in alkaline environment

The electrochemical oxidation of ammonia to dinitrogen is a model reaction for the electrocatalysis of the nitrogen cycle, as it can contribute to the understanding of the making/breaking of N—N, N—O, or N—H bonds. Moreover, it can be used as the anode reaction in ammonia electrolyzers for H 2 production or in ammonia fuel cells. Here, we study the reaction on the N 2 -forming Pt(1 0 0) electrode using a combination of electrochemical methods, product characterization and computational methods, and suggest a mechanism that is compatible with the experimental and theoretical findings. We propose that N 2 is formed via an *NH + *NH coupling step, in accordance with the Gerischer-Mauerer mechanism. Other N—N bond forming steps are considered less likely based on either their unfavourable energetics or the low coverage of the necessary monomers. The N—N coupling is inhibited by strongly adsorbed *N and *NO species, which are formed by further oxidation of *NH.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Hydrogen losses in fueling station operation

This paper describes an engineering approach for hydrogen accounting from production to dispensing at Cal State Los Angeles Hydrogen Research and Fueling Facility, equipped with an electrolyzer for on-site production. Particularly, the accounting process has been carried out by taking an in-depth look at current practices and databases, and its analysis has been based on data from quarterly reports of hydrogen production and dispensing related parameters and from its data acquisition system. It is described how the station addressed this analysis investigating several station areas. Following there is an assessment of the possible critical points, flanked by considerations, calculations, mathematical modeling and analysis of the database. The analysis led to a marked improvement on the station operation know-how. For most of the analyzed months the current average percentage of losses was found to be between 2 and 10%, whereas before it was between 30 and 35%. This current range of percentage (2–10)% includes all experiments done, defueling the buffer tanks, rebooting the dispenser, venting the lines, the uncertainty of the mass flow meter inside the dispenser (±5%) and the inherent uncertainty of Faraday’s law for hydrogen production estimate. Among all areas analyzed, maintenance activities revealed themselves as the most critical ones, leading to data mismatching in hydrogen accounting. The paper aims also to provide a guideline with recommended practices based on our experience, deduced for station operators and builders, including several steps for leakage monitoring, prevention, and troubleshooting.

08 HYDROGEN↗
DOE OSTI2022

An economic analysis of the role of materials, system engineering, and performance in electrochemical carbon dioxide conversion to formate

The development of technologies that utilize carbon dioxide is important to mitigating climate change. The electrochemical reduction of carbon dioxide is one technology that can utilize greenhouse gasses that would be otherwise be emitted to the atmosphere by producing chemicals and fuels from carbon dioxide and electricity. Significant progress has been made in the experimental performance of carbon dioxide reduction systems with novel catalyst designs, new materials, and systems engineering; however, no work has linked such changes in stack design and materials to capital costs for the stack itself. In this study, we present an analysis that accounts for and analyzes the impacts of alternative materials and system architectures on manufactured costs of carbon dioxide reduction stacks, thus providing a framework to understand exactly how these advances impact the at-scale capital costs of these systems. Specifically, we consider the impact that the addition of a catholyte buffer layer has on an electrolyzer reducing carbon dioxide to formate, finding that the cost of manufacturing this part only increases stack costs by about $30/m 2 at high manufacturing rates, while previous work finds that this part improves system performance. This work shows that the links between system performance, materials, and costs are nonlinear, and that achieving low-cost scalability requires optimization of not just performance parameters but also the use of low-cost and highly scalable materials. These results bridge experimental and techno-economic analysis of processes for carbon dioxide reduction, informing researchers by providing a quantifiable estimate of the impact of advances in electrochemical carbon dioxide reduction technology on manufactured stack capital costs.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2021

Scalable fabrication of high activity nanoporous copper powders for electrochemical CO 2 reduction via ball milling and dealloying

Electrochemical CO 2 reduction (ECR) is a promising technology to close the anthropic CO 2 circle using renewable energy to achieve carbon neutrality. Future commercialization of ECR will require the development of new catalyst synthesis routes that will allow significant upscaling of catalyst production from current research-level milligram quantities to the kilogram scale and beyond while maintaining the activity and selectivity demonstrated at the research level. Here, we report on generating and testing submicron-sized nanoporous copper (npCu) particles by using a scalable approach consisting of ball milling brittle Cu-based intermetallics followed by dealloying to add nanoporosity for high surface area. The resulting npCu particles have been tested in an industry-relevant large area (25 cm 2 ) electrolyzer platform and showed Faraday efficiencies (FE) for ethylene up to 34 % at current densities of 75–100 mA/cm 2 while keeping FE for hydrogen less than 30 %. Our results demonstrate that a combination of ball milling and dealloying is a promising approach to generate large quantities of high activity and high surface area npCu particles for ECR at an industry-relevant scale.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2017

Reaction mechanism for oxygen evolution on RuO 2 , IrO 2 , and RuO 2 @IrO 2 core-shell nanocatalysts

Iridium dioxide, IrO 2 , is second to the most active RuO 2 catalyst for the oxygen evolution reaction (OER) in acid, and is used in proton exchange membrane water electrolyzers due to its high durability. In order to improve the activity of IrO 2 -based catalysts, we prepared RuO 2 @IrO 2 core-shell nanocatalysts using carbon-supported Ru as the template. At 1.48 V, the OER specific activity of RuO 2 @IrO 2 is threefold that of IrO 2 . While the activity volcano plots over wide range of materials have been reported, zooming into the top region to clarify the rate limiting steps of most active catalysts is important for further activity enhancement. Here, we verified theory-proposed sequential water dissociation pathway in which the O—O bond forms on a single metal site, not via coupling of two adsorbed intermediates, by fitting measured polarization curves using a kinetic equation with the free energies of adsorption and activation as the parameters. Consistent with theoretical calculations, we show that the OER activities of IrO 2 and RuO 2 @IrO 2 are limited by the formation of O adsorbed phase, while the OOH formation on the adsorbed O limits the reaction rate on RuO 2 .

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

Additive manufacturing of ceramic materials for energy applications: Road map and opportunities

Among engineering materials, ceramics are indispensable in energy applications such as batteries, capacitors, solar cells, smart glass, fuel cells and electrolyzers, nuclear power plants, thermoelectrics, thermoionics, carbon capture and storage, control of harmful emission from combustion engines, piezoelectrics, turbines and heat exchangers, among others. Advances in additive manufacturing (AM) offer new opportunities to fabricate these devices in geometries unachievable previously and may provide higher efficiencies and performance, all at lower costs. This article reviews the state of the art in ceramic materials for various energy applications. The focus of the review is on material selections, processing, and opportunities for AM technologies in energy related ceramic materials manufacturing. The aim of the article is to provide a roadmap for stakeholders such as industry, academia and funding agencies on research and development in additive manufacturing of ceramic materials toward more efficient, cost-effective, and reliable energy systems.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Optimizing investments in coupled offshore wind-electrolytic hydrogen storage systems in Denmark

In response to electricity markets with growing levels of wind energy production and varying electricity prices, this research examines incentives for investments in integrated renewable energy power systems. A strategy for using optimization methods for a power system consisting of wind turbines, electrolyzers, and hydrogen fuel cells is explored. This research reveals the investment potential of coupling offshore wind farms with different hydrogen systems. The benefits in terms of a return on investment are demonstrated with data from the Danish electricity markets. This research also investigates the tradeoffs between selling the hydrogen directly to customers or using it as a storage medium to re-generate electricity at a time when it is more valuable. Finally, this research finds that the most beneficial configuration is to produce hydrogen at a time that complements the wind farm and sell the hydrogen directly to end users.

25 ENERGY STORAGE↗
DOE OSTI2018

Quantifying the flexibility of hydrogen production systems to support large-scale renewable energy integration

Hydrogen is a flexible energy carrier that can be produced in various ways and support a variety of applications including industrial processes, energy storage and electricity production, and can serve as an alternative transportation fuel. Hydrogen can be integrated in multiple energy sectors and has the potential to increase overall energy system flexibility, improve energy security, and reduce environmental impact. In this paper, the interactions between fuel cell electric vehicles (FCEVs), hydrogen production facilities, and the electric power grid are explored. The flexibility of hydrogen production systems can create synergistic opportunities to better integrate renewable sources into the electricity system. To quantify this potential, we project the hourly system-wide balancing challenges in California out to 2025 as more renewables are deployed and electricity demand continues to grow. Passenger FCEV adoption and refueling behavior are modeled in detail to spatially and temporally resolve the hydrogen demand. We then quantify the system-wide balancing benefits of controlling hydrogen production from water electrolysis to mitigate renewable intermittency, without compromising the mobility needs of FCEV drivers. Finally, a control algorithm that can achieve different objectives, including peak shaving, valley filling, and ramping mitigation is proposed. Here, our results show that oversizing electrolyzers can provide considerable benefits to mitigate renewable intermittency, while also supporting the deployment of hydrogen vehicles to help decarbonize the transportation sector.

08 HYDROGEN↗
DOE OSTI2023

Atomically dispersed Pt single sites and nanoengineered structural defects enable a high electrocatalytic activity and durability for hydrogen evolution reaction and overall urea electrolysis

The scarcity and high cost of PGM electrocatalysts are the key bottleneck in the mass-scale commercialization of many electrolysis technologies. Bifunctional single-atom electrocatalysts (SACs) are promising alternatives for PGM electrocatalysts in next-generation electrolysis technologies because of their superior intrinsic activity and perfect atom utilization. Regulating the coordination environment of platinum atomic sites identifies their electrocatalytic performance. Therefore, exploring more appropriate supports could facilitate the construction of active and durable electrocatalysts with ultralow noble metal content. Herein, we report on a reliable approach for producing a novel type of SACs composed of atomically dispersed Pt active sites stabilized on defective NiCo layered double hydroxide (Pt/D-NiCo LDH) nanosheets as an ultralow-Pt hybrid electrocatalyst for hydrogen evolution reaction (HER), urea oxidation reaction (UOR), and full urea-water electrolysis. The optimized Pt 1 /D NiCo LDH-24 SAC displays a remarkable HER and UOR performance where it yields a current density of 10 mA cm -2 at 37 mV and 1.25 V vs. RHE for HER and UOR, respectively. Finally, symmetrical urea electrolyzer constructed of Pt 1 /D-NiCo LDH-24 electrodes attains 10 mA cm -2 at a cell voltage of 1.32 V vs. RHE, demonstrating superior activity and durability over 60 h operation when compared to commercial Pt/C( + )||RuO 2 ( - ) system.

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

Aging gracefully? Investigating iridium oxide ink's impact on microstructure, catalyst/ionomer interface, and PEMWE performance

Here, in this study, we conducted a thorough investigation of the impact of aging iridium oxide (IrO 2 ) perfluorosulfonic acid ionomer ink for up to 14 days on the properties of the ink and the resulting catalyst layers. We examined ink properties, such as zeta potential, dynamic light scattering (DLS), density, surface tension, and rheology, as functions of ink aging time. To evaluate the microstructure and catalyst/ionomer interface, we employed transmission electron microscopy (TEM), X-ray scattering, and X-ray photoelectron spectroscopy (XPS) techniques. Furthermore, we assessed the effect of ink aging on the performance of proton exchange membrane water electrolyzers (PEMWEs). Our findings reveal that most ink properties remain stable for 14 days. The variations in PEMWE cell performance are minimal, and no clear trend is observed in relation to ink aging time. This study demonstrates that the effects of aging the inks for 14 days on ink properties, catalyst layer structure, catalyst/ionomer interface, and PEMWE performance are negligible, indicating a substantial time window after ink preparation without any significant changes in its properties. These insights provide crucial guidance for the commercial production and coating processes of ink, which is necessary for scaling up PEM technologies to meet future demand.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2025

Performance improvement of proton exchange membrane water electrolysis by surface modification of porous transport layers

Proton exchange membrane water electrolysis (PEMWE) is a promising option for hydrogen production from a variety of energy sources. Cost-effective production of hydrogen with PEMWE requires reduction of costly precious metals as well as optimization of the components and interfaces in the cell. The interface between the platinum-coated titanium porous transport layer (PTL) and catalyst layer (CL) significantly impacts the performance of the electrolyzer cell. Here, we report on two PTL modification methods, mechanical abrasion and chemical etching, which we find improve PEMWE performance by lowering the resistance of the PTL/CL interface. The PTL surface modifications enabled performance improvements up to 77 mV at 4 A cm −2 and reduction of the high frequency resistance, demonstrating that the resistance of the PTL/CL interface is a significant factor in the cell performance. The PTL surface roughness was varied using abrasive materials ranging from 0.1 to 140 μm in grain sizes and chemical etching was found to also increase the surface roughness. The surface roughness was quantified using confocal laser microscopy and the surface oxidation was measured using X-ray photoemission spectroscopy. These results demonstrate that both increasing surface roughness and oxide removal contribute to lowering the PTL/CL interfacial resistance and increasing cell performance.

08 HYDROGEN↗
DOE OSTI2014

Solid state {sup 31}P MAS NMR spectroscopy and conductivity measurements on NbOPO{sub 4} and H{sub 3}PO{sub 4} composite materials

A systematic study of composite powders of niobium oxide phosphate (NbOPO{sub 4}) and phosphoric acid (H{sub 3}PO{sub 4}) has been performed in order to characterize the material's ability to perform as an electrolyte material in medium temperature fuel cells and electrolyzers. Powders of H{sub 3}PO{sub 4} contents between 13.1 and 74.2 M% were produced and characterized with powder X-ray diffraction, {sup 31}P MAS NMR and impedance spectroscopy. NMR revealed that a significant degree of dehydration and vaporization of H{sub 3}PO{sub 4} takes place above 200 °C, and increases with temperature. At 500 °C the NbOPO{sub 4} and H{sub 3}PO{sub 4} has reacted to form niobium pyrophosphate (Nb{sub 2}P{sub 4}O{sub 15}). Impedance spectroscopy showed an increase in conductivity with increasing acid concentration, whereas the conductivity decreased slightly with increasing temperature. The highest conductivity measured was 2.5·10{sup −3} S/cm for a sample containing 74.2 M% of H{sub 3}PO{sub 4}. Lastly, it was shown that NbOPO{sub 4} has no significant conductivity of its own. - Graphical abstract: Conductivity of NbOPO{sub 4}/H{sub 3}PO{sub 4} composites as a function of equivalent P{sub 2}O{sub 5} content. The conductivity is insignificant for pure NbOPO{sub 4}. - Highlights: • Composites have been made from NbOPO{sub 4} and H{sub 3}PO{sub 4}. • The composites composition has been investigated with solid state NMR. • The composites have shown clear signs of acid dehydration upon heating. • The conductivity of the composites increases for increasing acid content. • NbOPO{sub 4} has no significant conductivity of its own.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗