Technological assessment of selected hydrogen processes
The production of hydrogen by steam-methane reforming is discussed. Data cover production capacity, heat sources, reformer process conditions, shift conversion, and purification.
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The production of hydrogen by steam-methane reforming is discussed. Data cover production capacity, heat sources, reformer process conditions, shift conversion, and purification.
An analysis is presented of various ceramic design concepts intended to improve nozzle throat life and tunnel performance in the hypersonic Langley 8-Foot High-Temperature Structures Tunnel, which uses methane-air combustion products as the wind-tunnel test medium. Calculations of the axial pressure distribution and heating rates in the air-cooled nozzle throat are presented, and desirable characteristics of a ceramic material to be used in the nozzle throat are outlined, including high-temperature strength, thermal shock and erosion resistance, low conductivity and low thermal expansion. Ceramic nozzle throat design concepts are then examined, with attention given to monolithic and layered constructions of cast ceramics, reaction-bonded materials and a fiber-reinforced silica-silica ceramic. Results of a finite element analysis of the temperatures and stresses characteristic of the various concepts are then presented which indicate the monolithic silica-silica and the layered silica-silica/reaction bonded silicon nitride concepts to be the most promising of those investigated.
This paper presents some recent concepts in Mars Sample Return (MSR) missions that utilize extraterrestrial resources. The concepts examined include the power and energy needs of this mission. It is shown that solar energy is not especially attractive. Radioisotopic power generator and a Rankine cycle use are seen to be viable options. Quantitative estimates, taking into consideration state-of-the-art and projected technologies indicate that the power/energy per se is not critical to the mission - but reliability is. Hence, various modern options for the components of the power generation and utilization are discussed. The dramatic savings in Shuttle (or other) vehicle launches are quantitatively plotted. The basic system that is discussed here is the production of hydrocarbon (methane) fuel and oxygen from Martian atmosphere. For the simplest mission, it is seen that earth-carried methane burned with oxygen produced on site provides the best system.
Lunar traction systems, Mars oxygen production, and Mars methane engine operation were the three topics studied during 1992. An elastic loop track system for lunar construction operations was redesigned and is being tested. A great deal of work on simulating the lunar environment to facilitate traction testing has been reported. Operation of an oxygen processor under vacuum conditions has been the focus of another design team. They have redesigned the processor facility. This included improved seals and heat shields. Assuming methane and oxygen can be produced from surface resources on Mars, a third design team has addressed the problem of using Mars atmospheric carbon dioxide to control combustion temperatures in an internal combustion engine. That team has identified appropriate tests and instrumentation. They have reported on the test rig that they designed and the computer-based system for acquiring data.
The results of the investigation were presented at a Astrobiology Institute General Meeting. Seafloor hydrothermal systems may be the most likely locations on the early Earth for the emergence of life. Because of the disequilibrium inherent in such dynamic, mixing environments, abundant chemical energy would have been available for formation of the building blocks of life. In addition, theoretical studies suggest that organic compounds in these conditions would reach metastable states, due to kinetic barriers to the formation of stable equilibrium products (CO2 and methane). The speciation of organic carbon in metastable states is highly dependent on the oxidation state, pH, temperature, pressure and bulk composition of the system. The goal of our research is to investigate the effects of a number external variables on the formation, transformation, and stability of organic compounds at hydrothermal conditions. We have begun experimental work to attempt to control the oxidation state of simulated hydrothermal systems by using buffers composed of mineral powders and gas mixtures. We are also beginning to test the stability of organic compounds under these conditions.
Main findings: 1) supplementing very dilute media for cultivation of CB with analogs of lunar or Martian regolith effectively supported the proliferation of CB; 2) O2 evolution by siderophilic cyanobacteria cultivated in diluted media but supplemented with iron-rich rocks was higher than O2 evolution by same strain in undiluted medium; 3) preliminary data suggest that organic acids produced by CB are involved in iron-rich mineral dissolution; 4) the CB studied can accumulate iron on and in their cells; 4) sequencing of the cyanobacterium JSC-1 genome revealed that this strain possesses molecular features which make it applicable for the cultivation in special photoreactors on Moon and Mars. Conclusion: As a result of pilot studies, we propose, to develop a concept for semi-closed integrated system that uses CB to extract useful elements to revitalize air and produce valuable biomolecules. Such a system could be the foundation of a self-sustaining extraterrestrial outpost (Hendrickx, De Wever et al., 2005; Handford, 2006). A potential advantage of a cyanobacterial photoreactor placed between LSS and ISRU loops is the possibility of supplying these systems with extracted elements and compounds from the regolith. In addition, waste regolith may be transformed into additional products such as methane, biomass, and organic and inorganic soil enrichment for the cultivation of higher plants.
Hybrid-poplar tree plantations provide a source for biofuel and biomass, but they also increase forest isoprene emissions. The consequences of increased isoprene emissions include higher rates of tropospheric ozone production, increases in the lifetime of methane, and increases in atmospheric aerosol production, all of which affect the global energy budget and/or lead to the degradation of air quality. Using RNA interference (RNAi) to suppress isoprene emission, we show that this trait, which is thought to be required for the tolerance of abiotic stress, is not required for high rates of photosynthesis and woody biomass production in the agroforest plantation environment, even in areas with high levels of climatic stress. Biomass production over 4 y in plantations in Arizona and Oregon was similar among genetic lines that emitted or did not emit significant amounts of isoprene. Lines that had substantially reduced isoprene emission rates also showed decreases in flavonol pigments, which reduce oxidative damage during extremes of abiotic stress, a pattern that would be expected to amplify metabolic dysfunction in the absence of isoprene production in stress-prone climate regimes. However, compensatory increases in the expression of other proteomic components, especially those associated with the production of protective compounds, such as carotenoids and terpenoids, and the fact that most biomass is produced prior to the hottest and driest part of the growing season explain the observed pattern of high biomass production with low isoprene emission. Our results show that it is possible to reduce the deleterious influences of isoprene on the atmosphere, while sustaining woody biomass production in temperate agroforest plantations.
As the world endures environmental crises associated with climate change and the rise of atmospheric CO2 concentrations from anthropogenic CO2 emission, carbon capture and utilization (CCU) technologies are increasingly necessary. Reactive carbon capture (RCC) technologies, in which capture and conversion of CO2 occur in a single reactor, are more energetically and economically attractive by avoiding the need to purify, compress, and transport the captured CO2. To this end, the development of dual function materials (DFM) that enable CO2 capture and conversion to useful C1 products, namely (1) methane, (2) CO, and (3) methanol, are attractive near-term targets for commercial CCU processes for renewable fuels and chemicals. DFM are composed of sorbents and catalysts co-dispersed on the same high surface area carrier. The sorbent component allows for selective capture of CO2 from a gas stream and the catalyst component subsequently performs the in-situ conversion of the adsorbed CO2 upon introduction of a reactive gas (typically H2). The survey of DFM formulations reveals a variety of sorbent+catalyst combinations of interest. There is, however, a lack of depth in fundamental understanding of how the CO2 binds to these materials and how the subsequent reaction mechanisms are affected, which are critical features for the development of next-generation materials with improved performance. To this end, we will describe in this work the CO2 binding characteristics of established and/or new DFM and their sorbent-only counterparts. The surface CO2 binding mechanism and capture capacity will be probed using techniques such as in-situ DRIFTS, operando TGA, and CO2 chemisorption.
Due to the recent boom in shale gas production, aromatics production using direct nonoxidative methane dehydroaromatization (DHA) is being investigated extensively. However, due to rapid coke formation, catalysts in the nonoxidative methane DHA reactors get deactivated, which is one of the critical issues for the commercial success of the methane DHA process. In this paper, a model for catalyst deactivation is developed. Rate models for other DHA reactions are developed by considering the decrease in the catalyst activity with time. Due to the very fast coke formation rate on the fresh catalyst, there is coke formation immediately upon the introduction of the feed. Therefore, an algorithm is developed for estimation of the initial state of the reactor and the kinetic parameters by coupling an iterative direct substitution approach with an optimization approach. Transient experimental data from an in-house reactor are first reconciled and then used for developing the kinetic model including the coke formation model. Using the rate model, a dynamic, heterogeneous, multiscale reactor model with embedded heating is developed. Here, the model couples the catalyst pellet level model with a reactor level model. Impacts of temperature, L/D ratio, and scheduling of reactors on variability in conversion and yield with time are studied.
This project focuses on developing an advanced, intensified anaerobic digestion system aimed at transforming the treatment and conversion of organic wastes into valuable products, specifically renewable natural gas. The motivation for this research stems from the limitations of conventional anaerobic digestion technologies, which often face challenges such as long retention times, high operational costs, and incomplete organic material degradation. The new technology called Intensified Versatile Anaerobic Digestion (IVAD), is developed to address these challenges by incorporating innovative reactors and processes that enhance the overall efficiency and output of anaerobic digestion. The significance of this project lies in its potential to revolutionize waste management practices and waste biomass utilization. The IVAD system integrates a hyperthermophilic anaerobic acidification reactor, a hydrothermal treatment (HTT) unit, and both thermophilic and mesophilic methanogenic reactors. This combination enables a higher rate of organic breakdown and energy recovery, resulting in faster processing times, reduced reactor sizes, and lower operational costs compared to traditional systems. Key data include an increase in methane productivity to 1.18 m 3 /m 3 /day, a significant improvement compared to the baseline technology’s 0.64 m 3 /m 3 /day. Additionally, the IVAD system achieves a 45% reduction in levelized cost of energy (LCOE), down to $\$$10.04/MMBTU, and an energy return on investment (EROI) of 3.19, representing an 87% increase over baseline levels. Technical and economic analyses highlight that the IVAD system significantly reduces hydraulic retention time (HRT) and solid retention time (SRT). The HRT for the HTT reactor can be reduced from 1 hour to 0.5 hours, while decoupling SRT from HRT in the anaerobic acidification reactor (AAR) allows for further reductions. These design optimizations lead to smaller reactor volumes, cutting down equipment and construction costs. Despite these advancements, energy consumption remains comparable to conventional methods due to a novel heat recovery strategy, enhancing overall process productivity. The system also achieves in-situ CO 2 removal and ammonia stripping features, resulting in biogas with a methane purity level of 75%, and produces high-quality nitrogen fertilizer as an additional by-product. Public benefits of the IVAD system are substantial, contributing to sustainable waste management and renewable energy production. By providing a scalable solution that can be adopted by dairy farms and similar agricultural operations, the IVAD system helps reduce waste, produce renewable natural gas (RNG) suitable for transportation fuel, and generate fertilizer, supporting a circular economy. This project plays a role in achieving broader environmental objectives by mitigating greenhouse gas emissions and promoting energy independence. Additionally, it offers a pathway for farmers to lower operational costs while adopting practices that are both environmentally sustainable and economically advantageous.
The increasing interest in utilizing methane, the primary component of natural gas, for chemical production has spurred research into methane partial oxidation (MPO) as an alternative to traditional steam methane reforming (SMR). MPO has lower energy requirements and potential for carbon capture, making it an attractive option for hydrogen production. Challenges remain, however, such as carbon deposition leading to degradation and achieving high hydrogen selectivity. Here, the impact of periodic reactor operation on MPO over a Pt/Al 2 O 3 catalyst was studied, primarily via varying reactor inlet compositions. Experiments were conducted using periodic operation strategies to assess the influence of changing reactant inlet concentrations on hydrogen formation during MPO. The results suggest that cycling between mixtures with low and high oxygen content can lead to transient hydrogen formation rates that surpass those achieved at steady state. Control experiments and density functional theory (DFT) calculations show that enhanced hydrogen formation can be attributed to the reaction between CO with hydroxyl groups at the metal and alumina support interface. Furthermore, this work underscores the critical role of surface coverages at the metal–support interface and suggests avenues for future exploration, including alternative support materials with higher OH mobility and changes in the cycling scheme to enhance catalyst performance under periodic conditions.
The gas hydrate petroleum system (GHPS) approach, which has been used to characterize gas hydrates in nature, uses three distinct components: a methane source, a methane migration pathway, and a reservoir that not only contains gas hydrate, but also acts as a seal to prevent methane loss. Unlike GHPS, a traditional petroleum system (PS) approach further distinguishes between the reservoir, a unit with generally coarser sediment grains, and a separate overlying seal unit with generally finer sediment grains. Adopting this traditional PS distinction in the GHPS approach facilitates assessments of reservoir growth and production potential. The significance of the seal for the formation of a gas hydrate reservoir as well as for efficiency in methane extraction from the reservoir as an energy resource is evident in findings from recent offshore field expeditions, such as India’s second National Gas Hydrate Program expedition (NGHP-02). In regard to gas hydrate-bearing reservoir formations, the NGHP-02 gas chemistry data indicate a primarily microbial methane source. Fine-grained seal sediment in contact with coarser grained reservoir sediment can facilitate that microbial methane production. Logging-while-drilling and sediment core data also indicate that the overlying fine-grained seal sediment is less permeable than the underlying, highly gas hydrate-saturated reservoir sediment. The overlying seal’s capacity to act as a low-permeability boundary is important not only for preventing methane migration out of the reservoir over time, but also for preventing water invasion into the reservoir during methane extraction from the reservoir. Ultimately, the presence of an overlying, fine-grained, low-permeability “seal” influences how gas hydrate initially forms in a coarse-grained reservoir and dictates how efficiently methane can be extracted as an energy resource from the gas hydrate reservoir via depressurization.
The cost of sending mass into space with current propulsion technology is very expensive, making every item a crucial element of the space mission. It is essential that all materials be used to their fullest potential. Items like food, packaging, clothing, paper towels, gloves, etc., normally become trash and take up space after use. These waste materials are currently either burned up upon reentry in earth's atmosphere or sent on cargo return vehicles back to earth: a very wasteful method. The purpose of this project was to utilize these materials and create useful products like water and methane gas, which is used for rocket fuel, to further supply a deep space mission. The system used was a thermal degradation reactor with the configuration of a down-draft gasifier. The reactor was loaded with approximately 100g of trash simulant and heated with two external ceramic heaters with separate temperature control in order to create pyrolysis and gasification in one zone and incineration iri a second zone simultaneously. Trash was loaded into the top half of the reactor to undergo pyrolysis while the downdraft gas experienced gasification or incineration to treat tars and maximize the production of carbon dioxide. Minor products included carbon monoxide, methane, and other hydrocarbons. The carbon dioxide produced can be sent to a Sabatier reactor to convert the gas into methane, which can be used as rocket propellant. In order to maximize the carbon dioxide and useful gases produced, and minimize the unwanted tars and leftover ashen material, multiple experiments were performed with altered parameters such as differing temperatures, flow rates, and location of inlet air flow. According to the data received from these experiments, the process will be further scaled up and optimized to ultimately create a system that reduces trash buildup while at the same time providing enough useful gases to potentially fill a methane tank that could fuel a lunar ascent vehicle or other deep space mission.
The reactions of carbonyl oxides (“Criegee intermediates”) with organic and inorganic acids have been postulated to proceed predominantly by an insertion mechanism, and the hydroperoxy-substituted ester products from reactions with organic acids have been spectroscopically observed. Here this work characterizes the products from one of the simplest reactions of carbonyl oxides with inorganic acids, that of formaldehyde oxide, CH 2 OO, with hydrogen chloride, which occurs via a 1,2-insertion in the H–Cl bond. Reactions of both HCl and DCl isotopologues yield product signal at the mass of the insertion product chloro(hydroperoxy)methane and a dissociative ionisation peak at the mass of the protonated (or deuteronated) Criegee intermediate. The isotopic composition of the insertion product has been measured for reaction mixtures where both HCl isotopologues are present, and the H/D ratio of the product is consistently higher (by a factor of 1.6 ± 0.3) than that of the reactants. This isotope selectivity in the products has smaller uncertainty than the ratio of measured rate coefficients and suggests a normal (k H > k D ) kinetic isotope effect in the reaction. Theoretical kinetics calculations predict a small normal kinetic isotope effect for the overall reaction (k H / k D = 1.35 at 20 Torr N 2 and k H / k D = 1.2 for 1 atm N 2 ) but predict a substantial inverse kinetic isotope effect (k D > k H ) for the stabilisation fraction, in disagreement with the experimental observation.
As sustainability becomes increasingly critical, the brewing industry encounters challenges in managing high-organic-content wastewater, a promising renewable energy source. This study evaluates the economic feasibility and environmental impacts of converting brewery wastewater into renewable natural gas (RNG) through anaerobic digestion and biogas upgrading, with an emphasis on different hydrogen sources for biomethanation. Four scenarios were analyzed: Scenario 1 uses purchased hydrogen, while Scenarios 2–4 use renewable hydrogen from microbial electrolysis cells and water electrolyzers. Results show that capital investments for processing 139 MT/h of wastewater, yielding 208 m 3 /h of RNG, range from 10.6 M to 31.9M USD, with estimated minimum selling prices of RNG between 2.25 and 4.37 USD/m 3 . Life cycle greenhouse gas (GHG) emissions span from -21 to 32g CO 2 -equivalent per MJ of RNG. Further, this study presents key economic and environmental metrics for RNG production from brewery wastewater, offering insights to enhance sustainability in brewery wastewater management.
While a stimulating effect of plant primary productivity on soil carbon dioxide (CO 2 ) emissions has been well documented, links between gross primary productivity (GPP) and wetland methane (CH 4 ) emissions are less well investigated. Determination of the influence of primary productivity on wetland CH 4 emissions (FCH 4 ) is complicated by confounding influences of water table level and temperature on CH 4 production, which also vary seasonally. Here, in this work, we evaluate the link between preceding GPP and subsequent FCH 4 at two fens in Wisconsin using eddy covariance flux towers, Lost Creek (US-Los) and Allequash Creek (US-ALQ). Both wetlands are mosaics of forested and shrub wetlands, with US-Los being larger in scale and having a more open canopy. Co-located sites with multi-year observations of flux, hydrology, and meteorology provide an opportunity to measure and compare lag effects on FCH4 without interference due to differing climate. Daily average FCH4 from US-Los reached a maximum of 47.7 ηmol CH 4 m -2 s -1 during the study period, while US-ALQ was more than double at 117.9 ηmol CH 4 m -2 s -1 . The lagged influence of GPP on temperature-normalized FCH4 (T air -FCH 4 ) was weaker and more delayed in a year with anomalously high precipitation than a following drier year at both sites. FCH 4 at US-ALQ was lower coincident with higher stream discharge in the wet year (2019), potentially due to soil gas flushing during high precipitation events and lower water temperatures. Better understanding of the lagged influence of GPP on FCH 4 due to this study has implications for climate modeling and more accurate carbon budgeting.
This document provides a set of community-accepted practices for quantifying methane emissions based on plumes detected via spectroscopic remote sensing. Its primary goal is to promote consistency in the generation, validation, reporting, and quality assessment of methane emission estimates derived from remote sensing radiances. Developed by subject matter experts with deep experience across all stages of the measurement process, this guidance reflects a critical evaluation of current methodologies and highlights key practices needed to produce reliable, interoperable, and traceable products. The focus is specifically on methane emissions quantified from distinct plumes originating from localized sources, rather than diffuse emissions spread over large regions, which are beyond the scope of this work. This document is intended to serve both data producers and users. For producers, it offers a framework for aligning with field-recognized standards to ensure their outputs meet rigorous quality and transparency criteria. For users, it provides a reference to assess dataset fitness-for-purpose by highlighting essential metadata, assumptions, and methodological choices that underpin emission estimates. By fostering a shared understanding of best practices, this work aims to enhance comparability, confidence, and utility of remotely sensed methane emission products.
Selective catalytic hydrogenolysis of polyolefins is a promising route to convert plastic waste into valuable liquid products, such as lubricants, waxes, and surfactants. However, the high viscosity of polymer melts imposes mass transfer limitations on this reaction. Solvents can mitigate these challenges, but their effects on reaction kinetics and product selectivity remain underexplored. Here, we systematically explore the effects of small n-alkanes and cycloalkanes on the hydrogenolysis of polyethylene and polypropylene over a Ru/TiO 2 catalyst. Using kinetic measurements and isotopic labeling, we show that n-octane at high mass fractions alters the mechanism from direct hydrogenation to solvent-mediated hydrogen transfer, reducing the rate of C–C bond cleavage. Longer alkanes further inhibit reactivity due to stronger surface binding. 1,4-Dimethylcyclohexane suppresses methane formation, favoring heavier products, while decalin likely forms surface-bound aromatics that poison the catalyst. Overall, alkane solvents modulate product selectivity and reduce the yield of methane byproduct, allowing for ∼35–40% selectivity to valuable C 20 -C 30 alkane products. This work highlights the complex impact of polymer–alkane mixtures on hydrogenolysis kinetics relevant to the design of commercial-scale plastic waste valorization processes.