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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 OSTI2013

Hydrogen Pathways: Updated Cost, Well-to-Wheels Energy Use, and Emissions for the Current Technology Status of Ten Hydrogen Production, Delivery, and Distribution Scenarios

This report describes a life-cycle assessment conducted by the National Renewable Energy Laboratory (NREL) of 10 hydrogen production, delivery, dispensing, and use pathways that were evaluated for cost, energy use, and greenhouse gas (GHG) emissions. This evaluation updates and expands on a previous assessment of seven pathways conducted in 2009. This study summarizes key results, parameters, and sensitivities to those parameters for the 10 hydrogen pathways, reporting on the levelized cost of hydrogen in 2007 U.S. dollars as well as life-cycle well-to-wheels energy use and GHG emissions associated with the pathways.

08 HYDROGEN↗
DOE OSTI2023

Tradeoffs in life cycle water use and greenhouse gas emissions of hydrogen production pathways

Hydrogen has been promoted as a key component of global decarbonization efforts, with various past studies estimating carbon emissions for several production pathways, but little past work has considered its water resource needs. This life cycle analysis considers hydrogen production on a per-kilogram basis for 11 pathways, fossil and non-fossil. It also includes impacts of treating water to the required quality for hydrogen production. Greenhouse gas emissions results were in a range of –15 to +31 kg CO 2 e/kg H 2 produced. Water consumption varied more widely, from about 7 to 55 kg water/kg H 2 for fossil-based pathways and 530 to 3400 kg water/kg H 2 for biomass-based pathways. Electrolysis with various renewable electricity scenarios were also modeled. Altogether, there are challenging tradeoffs to be navigated to achieve a low carbon and water footprint in hydrogen economy.

08 HYDROGEN↗
DOE OSTI2023

Theoretical assessments of CO 2 activation and hydrogenation pathways on transition-metal surfaces

Carbon dioxide (CO 2 ) hydrogenation on transition-metal active sites offers a promising carbon utilization route toward mitigating greenhouse gas emissions. C 1 products are often formed in parallel during CO 2 hydrogenation, prompting investigations into the intrinsic properties of transition metals that drive activity and product selectivity. Here, in this work, close-packed surfaces of a selection of transition-metal catalysts (Ni, Co, Rh, Ru, Pd, and Pt) were studied with density functional theory (DFT) calculations to understand their fundamental reactivities for CO 2 transformation reactions. Results indicate that CO 2 conversion proceeds through CO* formation and hydrogenation to form C 1 products (* denotes an adsorbed species). Ni, Co, Rh, and Ru favor CO/CH 4 formation, while Pd and Pt favor CO/CH 3 OH formation. The ability of a metal to dissociate C-O bonds drives selectivity between CH 4 and CH 3 OH, while competition between CO* desorption and surface hydrogenation describes CO selectivities. The C-O bond dissociation steps often impose the highest barrier along CH 4 formation reaction profiles, suggesting their kinetic relevance for CH 4 formation rates. The provided DFT-derived data sets detail a comprehensive reaction network of elementary steps relevant to C 1 chemistries, ultimately offering a benchmark for insights into design strategies for materials that exploit transition-metal active sites in carbon capture or utilization processes.

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

Crystallographic dependence of CO 2 hydrogenation pathways over HCP-Co and FCC-Co catalysts

We report efficient conversion of CO 2 is of great significance for sustainable supply of chemicals and fuels. While Co-based catalysts are known to be effective for CO hydrogenation in Fischer-Tropsch synthesis, they work very differently in CO 2 hydrogenation. This study reveals a crystallographic dependence of reaction pathways for CO 2 hydrogenation on Co catalyst showing a new type of structure sensitivity and structure-activity-selectivity relationship for CO 2 conversion to chemicals and fuels. The experimental work on CO 2 conversion including steady-state isotopic transient kinetic analysis (SSITKA) using 13 C-labeled CO 2 shows a preferential CH 4 formation over HCP-Co but dominant CO formation over FCC-Co. The density functional theory calculations indicate that CO 2 does dissociate directly into chemisorbed CO * and O * on both HCP-Co and FCC-Co, but the CO * intermediates on HCP-Co prefer to be hydrogenated to form CH 4 whereas the CO* on FCC-Co preferentially desorb to form CO. The significantly altered adsorption strength of CO * due to the presence of chemisorbed O * and CO 2 * species on the catalyst surface is responsible for the mechanistic disconnection in product selectivity between the CO 2 and CO hydrogenation over Co catalysts. This study also shows that the addition of K to Co diminishes the direct impact of Co crystal structure, but improves the selectivity to C 2 + hydrocarbons along with higher CO 2 conversion. This seems to result from another pathway originating from HCOO* intermediate from bonding interaction of surface Co atoms with carbon in CO 2 , leading to the formation of CH x * whose coupling subsequently give rises to C 2 + products. The present study sheds new light into the crystallographic structural sensitivity of CO 2 hydrogenation towards the rational design of more selective catalysts for CO 2 conversion.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Impact of Ni promotion on the hydrogenation pathways of phenanthrene on MoS 2 /γ-Al 2 O 3

The reaction network and elementary steps of the hydrogenation of phenanthrene are explored on parent and Ni-promoted MoS2/c-Al2O3. Two pathways were identified, i.e., Path 1: Phenanthrene _ 9,10-dihydrophenanthrene (DiHPhe)?1,2,3,4,4a,9,10,10a-octahydro-phenanthrene (asymOHPhe), and Path 2: Phenanthrene ?1,2,3,4-tetrahydrophenanthrene (TetHPhe)?1,2,3,4,5,6,7,8-octahydrophenan threne. The steps TetHPhe?asymOHPhe (hydrogenation), and DiHPhe?TetHPhe (hydrogenationisomerization) become notable at phenanthrene conversions above 20%. The reaction preferentially proceeds via Path 1 (90% selectivity) on MoS2/Al2O3. Ni promotion (Ni/(Ni + Mo) molar ratio of 0.3 at the edges on MoS2) increases the hydrogenation activity per active edge twofold and leads to 50% selectivity to both pathways. The reaction orders in H2 vary from _0.8 on MoS2/Al2O3 to _1.2 on Ni-MoS2/Al2O3, whereas the reaction orders in phenanthrene (_0.6) hardly depend on Ni promotion. The reaction orders in H2S are zero on MoS2/Al2O3 and slightly negative on Ni-MoS2/Al2O3. DFT calculations indicate that phenanthrene is preferentially adsorbed parallel to the basal planes, while H is located at the edges perpendicular to the basal planes. Theory also suggests that Ni atoms, incorporated preferentially on the S-edges, increase the stability of hydrogenated intermediates. Hydrogenation of phenanthrene proceeds through quasi-equilibrated adsorption of the reactants followed by consecutive addition of hydrogen pairs to the adsorbed hydrocarbon. The rate determining steps for the formation of DiHPhe and TetHPhe are the addition of the first and second hydrogen pair, respectively. The concentration of SH groups (activated H at the edges) increases with Ni promotion linearly correlating the rates of Path 1 and Path 2, albeit with different functions. The enhancing effect of Ni on Path 2 is attributed to accelerated hydrogen addition to adsorbed hydrocarbons without important changes in their coverages.

Schachtl, Eva↗
DOE OSTI2025

Comparative life cycle assessment of various hydrogen pathways for cleaner methanol synthesis

This study evaluates the potential environmental impacts of e-methanol production using hydrogen from green, yellow, and blue sources, including Gas Switching Reforming for high purity hydrogen production with carbon capture (GSR-H 2 ), and compares their performance across current and renewable energy scenarios. Using a cradle-to-gate life cycle assessment (LCA), the study quantifies impacts across seven TRACI categories. Global warming potential (GWP) ranged from 0.28 kg CO 2 eq/kg MeOH for green hydrogen with renewables to 2.55 kg CO 2 eq/kg MeOH for SMR-CC under grid power. Among the scenarios, renewable electrolysis achieves the lowest GWP, while GSR-H 2 under renewable power offered the best balance of emissions reductions and resource efficiency among the fossil-based routes, offering a viable transitional solution in regions dependent on natural gas infrastructure. The study reveals GSR-H 2 's potential as an alternative to conventional steam methane reforming with carbon capture (SMR-CC), showing its advantages in carbon capture efficiency and reduced life cycle emissions as well as significantly lower water consumption. GSR-H 2 , when powered by renewables, consumed only 1.41 L of water per kg MeOH, an 82% reduction compared to grid-powered electrolysis, highlighting its potential in water-scarce regions. This study is the first to evaluate GSR-H 2 as a hydrogen source for e-methanol, providing new evidence for its role as a cleaner, scalable transitional solution aligned with cleaner production principles.

08 HYDROGEN↗
DOE OSTI2020

Controlling Hydrocarbon (De)Hydrogenation Pathways with Bifunctional PtCu Single-Atom Alloys

The conversions of surface-bound alkyl groups to alkanes and alkenes are important steps in many heterogeneously catalyzed reactions. On the one hand, while Pt is ubiquitous in industry because of its high activity toward C–H activation, many Pt-based catalysts tend to overbind reactive intermediates, which leads to deactivation by carbon deposition and coke formation. On the other hand, Cu binds intermediates more weakly than Pt, but activation barriers tend to be higher on Cu. We examine the reactivity of ethyl, the simplest alkyl group that can undergo hydrogenation and dehydrogenation via β-elimination, and show that isolated Pt atoms in Cu enable low-temperature hydrogenation of ethyl, unseen on Cu, while avoiding the decomposition pathways on pure Pt that lead to coking. Lastly, we confirm the predictions of our theoretical model and experimentally demonstrate that the selectivity of ethyl (de)hydrogenation can be controlled by changing the surface coverage of hydrogen.

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

Decarbonizing Hydrogen Production: Assessing A Net-Negative Pathway

Hydrogen is gaining prominence as a key factor in the world's transition to a cleaner energy future. The International Energy Agency (IEA)'s Global Hydrogen Review 2023 reports that the number of low-emission hydrogen production projects is increasing rapidly. The potential for growth in new applications such as heavy industry, transportation, and power generation is significant. The IEA urges more decisive action to spur demand for low-emission hydrogen to achieve climate goals. While hydrogen is produced through various industrial methods, each with its own advantages and disadvantages, low-carbon hydrogen is critical for mitigating climate change and is incentivized by the Clean Hydrogen Production Tax Credit (45V). To this end, we have evaluated a commercial technology that can produce low- or negative-carbon hydrogen via ethanol catalytic oxidative reforming. This study assessed life cycle greenhouse gas emissions (carbon intensity or CI) associated with the hydrogen production technology. A total of 24 scenarios were evaluated, encompassing (a) Gen1 versus Gen2 ethanol inputs, (b) carbon capture and sequestration (CCS) of upstream fermentation CO2, and (c) oxygen sourcing via air separation unit (ASU) versus purchased or on-site production of oxygen as a byproduct of hydrogen electrolysis with a proton exchange membrane (PEM). Key findings include that the base case CI for hydrogen production using Gen2 ethanol from corn stover is lower than Gen1 dry mill corn ethanol. The study also points out that the CI for hydrogen production using PEM-O2 is lower than that using ASU-O2, whether the PEM-O2 is produced on-site or off-site (importing). When sourcing oxygen from on-site PEM-O2, the Gen1 and Gen2 ethanol-derived hydrogen exhibit favorable net-negative CI values for all evaluated scenarios, especially if the upstream ethanol CCS is included. As a reference, the 45V regulatory threshold for generating clean hydrogen tax credits is a CI below 0.45 kg CO2e/kg hydrogen.

BIOMASS FUELS,HYDROGEN↗
DOE OSTI2016

Exceptionally High Rates of Biological Hydrogen Production by Biomimetic In Vitro Synthetic Enzymatic Pathways

Hydrogen production by water splitting energized by biomass sugars is one of the most promising technologies for distributed green H 2 production. Direct H 2 generation from NADPH, catalysed by an NADPH-dependent, soluble [NiFe]-hydrogenase (SH1) is thermodynamically unfavourable, resulting in slow volumetric productivity. We designed the biomimetic electron transport chain from NADPH to H 2 by the introduction of an oxygen-insensitive electron mediator benzyl viologen (BV) and an enzyme (NADPH rubredoxin oxidoreductase, NROR), catalysing electron transport between NADPH and BV. The H 2 generation rates using this biomimetic chain increased by approximately five-fold compared to those catalysed only by SH1. The peak volumetric H 2 productivity via the in vitro enzymatic pathway comprised of hyperthermophilic glucose 6-phosphate dehydrogenase, 6-phosphogluconolactonase, and 6-phosphogluconate dehydrogenase, NROR, and SH1 was 310 mmol H 2 /L h -1 , the highest rate yet reported. The concept of biomimetic electron transport chains could be applied to both in vitro and in vivo H 2 production biosystems and artificial photosynthesis.

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

Environmental life-cycle analysis of hydrogen technology pathways in the United States

Hydrogen is a zero-carbon energy carrier with potential to decarbonize industrial and transportation sectors, but its life-cycle greenhouse gas (GHG) emissions depend on its energy supply chain and carbon management measures (e.g., carbon capture and storage). Global support for clean hydrogen production and use has recently intensified. In the United States, Congress passed several laws that incentivize the production and use of renewable and low-carbon hydrogen, such as the Bipartisan Infrastructure Law (BIL) in 2021 and the Inflation Reduction Act (IRA) in 2022, which provides tax credits of up to $3/kg depending on the carbon intensity of the produced hydrogen. A comprehensive life-cycle accounting of GHG emissions associated with hydrogen production is needed to determine the carbon intensity of hydrogen throughout its value chain. In the United States, Argonne’s R&D GREET ® (Greenhouse Gases, Regulated emissions, and Energy use in Technologies) model has been widely used for hydrogen carbon intensity calculations. This paper describes the major hydrogen technology pathways considered in the United States and provides data sources and carbon intensity results for each of the hydrogen production and delivery pathways using consistent system boundaries and most recent technology performance and supply chain data.

Elgowainy, Amgad↗
DOE OSTI2023

A cost comparison of various hourly-reliable and net-zero hydrogen production pathways in the United States

Hydrogen (H 2 ) as an energy carrier may play a role in various hard-to-abate subsectors, but to maximize emission reductions, supplied hydrogen must be reliable, low-emission, and low-cost. Here, we build a model that enables direct comparison of the cost of producing net-zero, hourly-reliable hydrogen from various pathways. To reach net-zero targets, we assume upstream and residual facility emissions are mitigated using negative emission technologies. For the United States (California, Texas, and New York), model results indicate next-decade hybrid electricity-based solutions are lower cost ($2.02-$2.88/kg) than fossil-based pathways with natural gas leakage greater than 4% ($2.73-$5.94/kg). These results also apply to regions outside of the U.S. with a similar climate and electric grid. However, when omitting the net-zero emission constraint and considering the U.S. regulatory environment, electricity-based production only achieves cost-competitiveness with fossil-based pathways if embodied emissions of electricity inputs are not counted under U.S. Tax Code Section 45V guidance.

08 HYDROGEN↗
DOE OSTI2015

H{sub 2}S induces vasoconstriction of rat cerebral arteries via cAMP/adenylyl cyclase pathway

Hydrogen sulfide (H{sub 2}S), traditionally known for its toxic effects, is now involved in regulating vascular tone. Here we investigated the vasoconstrictive effect of H{sub 2}S on cerebral artery and the underlying mechanism. Sodium hydrosulfide (NaHS), a donor of H{sub 2}S, concentration-dependently induced vasoconstriction on basilar artery, which was enhanced in the presence of isoprenaline, a β-adrenoceptor agonist or forskolin, an adenylyl cyclase activator. Administration of NaHS attenuated the vasorelaxant effects of isoprenaline or forskolin. Meanwhile, the NaHS-induced vasoconstriction was diminished in the presence of 8B-cAMP, an analog of cAMP, but was not affected by Bay K-8644, a selective L-type Ca{sup 2+} channel agonist. These results could be explained by the revised effects of NaHS on isoprenaline-induced cAMP elevation and forskolin-stimulated adenylyl cyclase activity. Additionally, NaHS-induced vasoconstriction was enhanced by removing the endothelium or in the presence of L-NAME, an inhibitor of nitric oxide synthase. L-NAME only partially attenuated the effect of NaHS which was given together with forskolin on the pre-contracted artery. In conclusion, H{sub 2}S induces vasoconstriction of cerebral artery via, at least in part, cAMP/adenylyl cyclase pathway. - Highlights: • The vasoactivity effect of NaHS, a donor of H{sub 2}S, was studied on rat cerebral arteries. • H{sub 2}S induces a constriction, not a relaxant effect on basilar arteries. • The vasoconstrictive effect is invovled in inhibiting adenylyl cyclase to reduce cAMP levels. • The vasoconstriction is partially antagonized by NO, and does not necessarily act via NO pathway.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

A Cobalt Hydride Catalyst for the Hydrogenation of CO2: Pathways for Catalysis and Deactivation

The complex Co(dmpe)₂H catalyzes the hydrogenation of CO₂ at one atm and 21 ºC with significant improvement in turnover frequency relative to previously reported second and third row transition metal complexes. New studies are presented to elucidate the catalytic mechanism as well as pathways for catalyst deactivation. The catalytic rate was optimized through the choice of the base to match the pK a of the [Co(dmpe)₂(H)₂]⁺ intermediate. By using a strong enough base, the catalytic rate has a zero order dependence on the concentration of base and pressure of hydrogen, and a first order dependence on the pressure of CO₂. However, upon exceeding CO₂:H₂ ratios of greater than one, the catalytically inactive species [(μ-dmpe)(Co(dmpe)₂)₂]²⁺ and [Co(dmpe)₂CO]⁺ are observed. Research by M.S.J., M.T.M., A.M.A., and J.C.L. was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Research by M.L.H. and E.B.H. was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for the DOE by Battelle.

catalysis↗
DOE OSTI2022

Controlling Selectivity in Plasmonic Catalysis: Switching Reaction Pathway from Hydrogenation to Homocoupling Under Visible‐Light Irradiation

Abstract Plasmonic catalysis enables the use of light to accelerate molecular transformations. Its application to the control reaction selectivity is highly attractive but remains challenging. Here, we have found that the plasmonic properties in AgPd nanoparticles allowed different reaction pathways for tunable product formation under visible‐light irradiation. By employing the hydrogenation of phenylacetylene as a model transformation, we demonstrate that visible‐light irradiation can be employed to steer the reaction pathway from hydrogenation to homocoupling. Our data showed that the decrease in the concentration of H species at the surface due to plasmon‐enhanced H 2 desorption led to the control in selectivity. These results provide important insights into the understanding of reaction selectivity with light, paving the way for the application of plasmonic catalysis to the synthesis of 1,3‐diynes, and bringing the vision of light‐driven transformations with target selectivity one step closer to reality.

Peiris, Erandi↗