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DOE OSTI2025

Environmental Evaluation of Gas Switching Reforming for Low Carbon Hydrogen: A Power-to-X Study

Gas Switching Reforming for hydrogen production (GSR-H2) offers a promising pathway for producing low-carbon hydrogen at scale, with significant implications for Power-to-X (PtX) systems that rely on clean hydrogen as a feedstock for synthetic fuels and chemicals. GSR-H2 integrates inherent carbon capture and thermal self-sufficiency, positioning it as an efficient alternative to conventional steam methane reforming (SMR), proton exchange membrane (PEM) electrolysis, and chemical looping reforming (CLR). Unlike SMR, GSR-H2 avoids external natural gas combustion by leveraging exothermic redox cycles to generate process steam and recover electricity internally. Its innovative reactor design consolidates all reforming stages within a single reactor cluster, eliminating the need for solid circulation found in CLR, thereby reducing capital costs and improving system reliability and scalability. This presentation describes the first environmental life cycle assessment (LCA) of GSR-H2, evaluating its environmental performance across U.S. grid and renewable energy scenarios. In a renewables-powered configuration, GSR-H2 achieves a global warming potential (GWP) of 2.77 kg CO2 equivalent per kg H2, substantially lower than SMR (10.4 kg) and competitive with PEM electrolysis (1.85 kg) and CLR (1.84 kg). Results across additional impact categories, including air quality and water use, support GSR-H2’s role as a complementary hydrogen source in PtX applications. Its reduced environmental burden, thermal integration, and simplified scale-up potential make GSR-H2 a viable contributor to net-zero PtX systems, particularly where renewable energy is abundant and electricity-intensive hydrogen production faces economic or infrastructure constraints.

03 NATURAL GAS↗

NASA NTRS1987

Frequency stabilization in injection controlled pulsed CO2 lasers

Longitudinal mode selection by injection has been demonstrated as a viable technique for tailoring a TEA-CO2 laser with pulse energies of a Joule or greater to fit the requirements of a coherent lidar transmitter. Once reliable generation of single-longitudinal-mode (SLM) pulses is obtained, one can study the intrapulse frequency variation and attempt to determine the sources of frequency sweeping, or chirp. These sources include the effect of the decaying plasma, the thermal gradient due to the energy dissipation associated with the laser mechanism itself, and the pressure shift of the center frequency of the laser transition. The use of the positive-branch unstable resonator as an efficient means of coupling a discharge with transverse spatial dimensions of the order of centimeters to an optical cavity mode introduces another concern: namely, what can be done to emphasize transverse mode discrimination in an unstable resonator cavity while maintaining high coupling efficiency. These issues are briefly discussed in the paper, and representative experimental examples are included.

Menzies, Robert T.↗

NASA NTRS1995

Airborne measurements of NO, NO2, and NO(sub y) as related to NASA's TRACE-A field program

The Georgia Tech group's effort on NASA's GTE program and TRACE-A field mission primarily involved analysis and interpretation of the measurement data base obtained during the TRACE-A field campaign. These investigations focused on the distribution of ozone and ozone precursors over the south Atlantic and nearby continental regions of Africa and South Africa. The Transport and Atmospheric Chemistry near the Equator-Atlantic (TRACE-A) Mission was designed with the goal of investigating tropospheric trace gas distributions, sources, and photochemical state over the southern Atlantic. Major scientific issues related to N(x)O(y) tropospheric chemistry addressed in this program included: (1) what controls the tropospheric ozone budget over the southern Atlantic? (2) What are the spatial distributions of CO, CO2, NO, NO2, NO(sub y), O3, NMHC, H2O3, etc. over the southern Atlantic? (3) How does long range transport of long-lived NO(y) compounds affect the more reactive NO(x) budget in southern Atlantic troposphere?

Bradshaw, John↗

NASA NTRS1995

Incineration as a Method for Resource Recovery from Inedible Biomass in a Controlled Ecological Life Support System

Resource recovery from waste streams in a space habitat is essential to minimize the resupply burden and achieve self-sufficiency. In a Controlled Ecological Life Support System (CELSS) human wastes and inedible biomass will represent significant sources of secondary raw materials necessary for support of crop plant production (carbon, water, and inorganic plant nutrients). Incineration, pyrolysis, and water extraction have been investigated as candidate processes for recovery of these important resources from inedible biomass in a CELSS. During incineration CO2 is produced by oxidation of the organic components and this product can be directly utilized by plants. Water is concomitantly produced, requiring only a phase change for recovery. Recovery of inorganics is more difficult, requiring solubilization of the incinerator ash. The process of incineration followed by water solubilization of ash resulted in loss of 35% of the inorganics originally present in the biomass. Losses were attributed to volatilization (8%) and non-water-soluble ash (27%). All of the ash remaining following incineration could be solubilized with acid, with losses resulting from volatilization only. The recovery for individual elements varied. Elemental retention in the ash ranged from 100% of that present in the biomass for Ca, P, Mg, Na, and Si to 10% for Zn. The greatest water solubility was observed for potassium with recovery of approximately 77% of that present in the straw. Potassium represented 80% of the inorganic constituents in the wheat straw, and because of slightly greater solubility made up 86% of the water-soluble ash. Following incineration of inedible biomass from wheat, 65% of the inorganics originally present in the straw were recovered by water solubilization and 92% recovered by acid solubilization. Recovery of resources is more complex for pyrolysis and water extraction. Recovery of carbon, a resource of greater mass than the inorganic component of biomass, is more difficult following pyrolysis and water extraction of biomass. In both cases, additional processors would be required to provide products equivalent to those resulting from incineration alone. The carbon, water, and organic resources of inedible biomass are effectively separated and output in usable forms through incineration.

Bubenheim, David L.↗

NASA NTRS2012

Cometary Volatiles and the Origin of Comets

We describe recent results on the CO/C02/H2O composition of comets and compare these with models of the protoplanetary disk. We argue that the cometary observations require reactions on grain surfaces to convert CO to CO2 and also require formation between the CO and CO2 snow lines. This then requires very early mixing of cometesimals in the protoplanetary disk analogous to the mixing described for the asteroid belt by Walsh and Morbidelli. We suggest that most comets formed in the region of the giant planets. the traditional source of the Oort-cloud comets but not of the Jupiter-family comets

A'Hearn, Michael F.↗

NASA NTRS2017

Impact Delivery of Reduced Greenhouse Gases on Early Mars

Reducing greenhouse gases are once again the latest trend in finding solutions to the early Mars climate dilemma. In its current form - as proposed by Ramirez et al. [1], later refined by Wordsworth et al. [2], and confirmed by Ramirez [3] - collision induced absorptions between CO2-H2 or CO2-CH4 provide enough extra greenhouse power to raise global mean surface temperatures to the melting point of water provided the atmosphere is thick enough and the reduced gases are abundant enough. To raise surface temperatures significantly by this mechanism, surface pressures must be at least 500 mb and H2 and/or CH4 concentrations must be at or above the several percent level. Both Wordsworth et al. [2] and Ramirez [3] show that the melting point can be reached in atmospheres with 1-2 bars of CO2 and 2-10% H2; smaller concentrations of H2 will suffice if CH4 is also present. If thick weakly reducing atmospheres are the solution to the faint young Sun paradox, then plausible mechanisms must be found to generate and sustain the gases. Possible sources of reducing gases include volcanic outgassing, serpentinization, and impact delivery; sinks include photolyis, oxidation, and escape to space. The viability of the reduced greenhouse hypothesis depends, therefore, on the strength of these sources and sinks.

greenhose gases↗

DOE OSTI2024

Prospective Seal Unit Spatial Extent Database for U.S. Sedimentary Basins

The Prospective Seal Unit Spatial Extent Database for U.S. Sedimentary Basins contains a series of spatial datasets representing spatial extents of publicly available data for caprock and seal rock units within the Appalachian Basin, Denver-Julesburg Basin, Great Valley Basin (Sacramento and San Joaquin Basins), Illinois Basin, Michigan Basin, San Juan Basin, U.S. Gulf Coast Basin, and Williston Basin. The database is designed to support carbon storage feasibility and resources assessment for carbon transport and storage (CTS) projects while displaying the spatial extent of prospective seal units and provide a guide to the original data source. This database leverages publicly available data resources from authoritative sources (e.g. U.S. Geological Survey, State Geologic Surveys, and published reports), and aims to help guide users to understand the seal unit's spatial coverage and data gaps from the regional to sub-basin/field scale. The database is organized by seal unit/formation, including the spatial extent for data found to be available for the seal unit. The various datasets represented include spatial extents of the lithologic formation, depth to top structural contour maps, and thickness/isopach maps. Included in this submission are the following resources: 1. Geodatabase/Dataset: “prospective-seal-unit-extents-2025.gdb” 2. ReadMe: “readme-prospective-seal-unit-spatial-extent-dataset-2025.pdf” 3. Data Catalog: “prospective-seal-unit-spatial-extents-data-catalog-2025.xlsx” 4. Data Sources Key: “data-source.csv” Please see NETL disclaimers here: https://netl.doe.gov/home/disclaimer

Basin↗

DOE OSTI2023

Tropical Red Macroalgae Cultivation with a Focus on Compositional Analysis

To create carbon efficient sources of bioenergy feedstocks and feedstuff for aquaculture and terrestrial livestock, it is critical to develop and commercialize the most efficient seaweed cultivation approach with a sustainable nutrient input supply. Here, we present data for a novel, onshore tropical macroalgae cultivation system, based on influent deep seawater as the nutrient and carbon sources. Two red algal species were selected, Agardhiella subulata and Halymenia hawaiiana, as the basis for growth optimization. Highest productivity in small-scale cultivation was demonstrated with A. subulata in the 10% deep seawater (64.7 µg N L−1) treatment, growing at up to 26% specific growth rate day−1 with highest yields observed at 247.5 g m−2 day−1 fresh weight. The highest yields for H. hawaiiana were measured with the addition of 10% deep seawater up to 8.8% specific growth rate day−1 and yields at 63.3 g fresh weight m−2 day−1 equivalent. Biomass should be culled weekly or biweekly to avoid density limitations, which likely contributed to a decrease in SGR over time. With a measured 30–40% carbon content of the ash-free dry weight (20–30% of the dry weight) biomass, this translates to an almost 1:1 CO2 capture to biomass ratio. The compositional fingerprint of the high carbohydrate content of both Agardhiella and Halymenia makes for an attractive feedstock for downstream biorefinery applications. By focusing on scaling and optimizing seaweed farming technologies for large-scale onshore farms, the opportunities for yield potential, adaptability to cultivation conditions, and meeting global sustainability goals through novel, carbon-negative biomass sources such as seaweed can be realized.

09 BIOMASS FUELS↗

NASA NTRSDate not supplied

Comparing the Regional Variability of Emission Factors of Greenhouse Gases Over Different Landscape During FIREX-AQ Campaign

Biomass burning (wildfires, prescribed and agricultural burning) is one of the major sources of trace gases and particulate emissions and annual variability in growth rates. Biomass burning can impact local, regional, and global air quality, as well as climate. Measurements of emissions from biomass burning are crucial to a better understanding of how it influences and interacts with biogeochemical cycles. High resolution in-situ measurements were recorded onboard the NASA DC-8 aircraft during the FIREX-AQ (Fire Influence on Regional to Global Environments and Air Quality) airborne field campaign July-September, 2019, which was conducted over the continental U.S. Fire emission factors (EF) are essential input for emissions models used to develop biomass burning emission inventories. Here we present the Emission Ratio (ER), MCE (Modified Combustion Efficiency), and EF (Emission Factor) of CO2, CO, and CH4, which constitute the majority of carbon emitted from the wildland, prescribed, and agricultural fires. EFCO2, EFCO, and EFCH4 from the Wildland fires at Williams Flats, WA (primarily Douglas Fir, Ponderosa pine, wheatgrass: 50-75%), ranged from 1527 – 1820 g/kg (Avg. 1641±42), 6.5 – 174.1 g/kg (110.5±24.1), and 0.7 – 11.3 g/kg (6.2±1.9), respectively. EFs from the Arizona CASTLE fire, with somewhat different fuel sources (primarily Ponderosa pine, Douglas fir: 40-70%) ranged from 1266 – 1667 g/kg (1596±59), 99.5 – 344.5 g/kg (136.7±36.8), and 0.4 – 9.2 g/kg (7.2±1.7), respectively. Another primary driver of EFs is likely fire weather. Detailed variability of greenhouse gas EFs will be examined and presented in accordance with different fuels and fire conditions at burned areas, specifically within unique wildland and croplands, using the FCCS (Fuel Characteristic Classification System) 30m land cover identification and the Cropland Data Layer (CDL).

Biomass burning↗

NASA NTRSDate not supplied

Comparing the regional variability of emission factors of greenhouse gases over different landscape during FIREX-AQ campaign

Biomass burning↗

DOE OSTI2022

Challenges and Opportunities for the Development of Commercial Maritime Surface Vessel Nuclear Propulsion (CMNP)

Maritime transport and trade are currently responsible for producing nearly 1 billion metric tons of CO2 emissions annually, representing 2.5% of global greenhouse gas emissions. While maritime shipping is acknowledged as the most efficient carrier of goods in terms of its costs and carbon intensity, the sector relies overwhelmingly on the use of heavy fuel oil (HFO). This fuel source currently is unmatched in terms of its global availability, safety, security of supply, price, and energy density. Combined, these characteristics are responsible for the outsized contribution of the sector to the global economy: roughly 90% of all transported goods spend time at sea. Commercial maritime nuclear propulsion provides opportunities to transition maritime trade to clean energy but also comes with challenges. Both are covered in this report based on 60+ interviews with professionals from the maritime and nuclear energy sectors.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

NASA NTRS1983

Atmospheric composition - Influence of biology

The variability of atmospheric constituents influenced by biological organisms over various time scales is examined, together with the human contribution to atmospheric sulfur. The biogeochemistry of nitrogen is discussed, with an emphasis on N2O, NO, and microbially mediated reactions in soil and water. Carbon species are bound up mainly in sediments and the deep ocean, but human activities involving combustion may cause a doubling of the atmospheric levels of CO2 in the near future, which could produce a general low-level atmospheric warming. Longer term measurements are required to assess the effects of CH4 augmentation in the atmosphere through fuel combustion. Coal burning effectively doubles the amount of SO2 produced by natural sources, and reduces the pH of rainwater, thus posing hazards to fish, plankton, and mollusc life.

Mcelroy, M. B.↗

NASA NTRS1992

Control of on-orbit contamination for the Argos (P91-1) satellite

The ARGOS (P91-1) satellite presents a challenging combination of on-orbit contamination concerns while mandating a low-cost approach. Several experiment payloads contain contamination sensitive optics, another contains large quantities of CO2 and Xe for release in orbit, and one contains an NH3 fueled arc jet thruster. The latter includes a suite of sensors to measure contamination; so prelaunch calculations will be tested. Planned contamination control techniques include: physical separation of sensitive surfaces from contamination sources; flight covers to protect sensitive surfaces during early outgassing on-orbit; gas release and thruster operation early in the flight, before flight covers are opened; and careful control of plumes and venting through a detailed analysis of each.

Kelley, Joseph G.↗

NASA NTRSDate not supplied

EMU Ventilation Loop Simulation and Assessment of Contamination of the EMU Sublimator Hydrophilic Coating

Controlling moisture is a critical function performed in the space suit during extra vehicular activity (EVA) missions. Currently, this function is carried out by a sublimator, which is coated with a hydrophilic material. Tests have shown that siloxane compounds can off gas from the helmet absorption pad extension (HAP-E) and helmet absorption band (HAB) when they are at elevated temperatures and initial testing indicated that siloxanes could damage the hydrophilic coating. Therefore, more representative testing was needed. Important test considerations were source and destination kinetics, system geometries, scrubbing efficacy by the activated charcoal from the Metox canister, and other benefits that derive from active condensation occurring on the hydrophilic coating during exposure. A ventilation loop that was originally constructed to test hardware for control of CO2 and trace contaminants under EVA conditions was modified to conduct the siloxane off gassing tests. A vacuum compatible acrylic chamber was installed to simulate the suit volume. A steel beaker located in the chamber contained the HAP-E and HAB materials and was heated with two band heaters. The flow exiting the chamber passed through a LiOH cannister, which contained carbon beds to simulate their function in the Metox. The flow then was directed into a smaller volume that contained a coupon, which was coated with the hydrophilic material and was maintained at 10°C (50°F). Moisture was injected upstream of the suit volume simulator to maintain the dew point between 12.7°C (55°F) and 18.3°C (65°F). The pressure was controlled to between 3.8 and 4.4 psia, and the flow was held at 6 acfm. The system was run for an equivalent of 25 ten-hour EVAs, where the HAP-E/HAB materials were changed out after each EVA. The effect of the potential off gassing on the coupon was measured after each EVA period.

PLSS↗

DOE OSTI2021

A permafrost implementation in the simple carbon–climate model Hector v.2.3pf

Abstract. Permafrost currently stores more than a fourth of global soil carbon. A warming climate makes this carbon increasingly vulnerable to decomposition and release into the atmosphere in the form of greenhouse gases. The resulting climate feedback can be estimated using land surface models, but the high complexity and computational cost of these models make it challenging to use them for estimating uncertainty, exploring novel scenarios, and coupling with other models. We have added a representation of permafrost to the simple, open-source global carbon–climate model Hector, calibrated to be consistent with both historical data and 21st century Earth system model projections of permafrost thaw. We include permafrost as a separate land carbon pool that becomes available for decomposition into both methane (CH4) and carbon dioxide (CO2) once thawed; the thaw rate is controlled by region-specific air temperature increases from a preindustrial baseline. We found that by 2100 thawed permafrost carbon emissions increased Hector’s atmospheric CO2 concentration by 5 %–7 % and the atmospheric CH4 concentration by 7 %–12 %, depending on the future scenario, resulting in 0.2–0.25 ∘C of additional warming over the 21st century. The fraction of thawed permafrost carbon available for decomposition was the most significant parameter controlling the end-of-century temperature change in the model, explaining around 70 % of the temperature variance, and was distantly followed by the initial stock of permafrost carbon, which contributed to about 10 % of the temperature variance. The addition of permafrost in Hector provides a basis for the exploration of a suite of science questions, as Hector can be cheaply run over a wide range of parameter values to explore uncertainty and can be easily coupled with integrated assessment and other human system models to explore the economic consequences of warming from this feedback.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1991

Application of physical adsorption thermodynamics to heterogeneous chemistry on polar stratospheric clouds

Laboratory isotherms for the binding of several nonheterogeneously active atmospheric gases and for HCl to water ice are translated into adsorptive equilibrium constants and surface enthalpies. Extrapolation to polar conditions through the Clausius Clapeyron relation yields coverage estimates below the percent level for N2, Ar, CO2, and CO, suggesting that the crystal faces of type II stratospheric cloud particles may be regarded as clean with respect to these species. For HCl, and perhaps HF and HNO3, estimates rise to several percent, and the adsorbed layer may offer acid or proton sources alternate to the bulk solid for heterogeneous reactions with stratospheric nitrates. Measurements are lacking for many key atmospheric molecules on water ice, and almost entirely for nitric acid trihydrate as substrate. Adsorptive equilibria enter into gas to particle mass flux descriptions, and the binding energy determines rates for desorption of, and encounter between, potential surface reactants.

Elliott, Scott↗

NASA NTRS1992

Cryogenic limb array etalon spectrometer (CLAES) - Experiment description and initial results

The primary objective of the CLAES experiment is to measure the altitude profiles of temperature and of a series of minor and trace species important to stratospheric ozone layer photochemistry and radiative structure. Ways in which the species to be measured by CLAES are distributed among the broad categories of source, radical, and reservoir species involved in ozone production and loss are illustrated. CLAES requires high spectral resolution and high radiometric sensitivity to isolate and accurately measure weak emissions from trace species such as HCl and NO against intense backgrounds from abundant emitters such as CO2, H2O, and O3. Spectroscopy is performed by tilt scanning one of the four solid etalons between 0 and 23 deg in conjunction with one or more of the nine selectable discrete interference filters.

Roche, Aidan E.↗

NASA NTRS1994

Proposed law of nature linking impacts, plume volcanism, and Milankovitch cycles to terrestrial vertebrate mass extinctions via greenhouse-embryo death coupling

A greenhouse-physiological coupling killing mechanism active among mammals, birds, and reptiles has been identified. Operating via environmental thermal effects upon the maternal core-skin blood flow critical to the survival and development of embryos, it reduces the flow of blood to the uterine tract. Today, during hot summers, this phenomena kills embryos on a vast, global scale. Because of sensitivity of many mammals to modern heat, a major modern greenhouse could reduce population numbers on a global scale, and potentially trigger population collapses in the more vulnerable parts of the world. In the geological past, the killing mechanism has likely been triggered into action by greenhouse warming via impact events, plume volcanism, and Earth orbital variations (Milankovitch cycles). Earth's biosphere is maintained and molded by the flow of energy from the solar energy source to Earth and on to the space energy sink (SES). This SES energy flow maintains Earth's biosphere and its living components, as open, intermediate, dissipative, nonequilibrium systems whose states are dependent upon the rate of energy flowing through them. Greenhouse gases such as CO2 in the atmosphere influence the SES energy flow rate. Steady-state flow is necessary for global ecological stability (autopoiesis). Natural fluctuations of the C cycle such as rapid releases of CO2 from the mantle, or oceans, disrupt steady-state SES flow. These fluctuations constantly challenge the biosphere; slowdown of SES energy flow drives it toward thermodynamical equilibrium and stagnation. Fluctuations induced by impact event, mantle plume volcanism, and Milankovitch cycles can grow into structure-breaking waves triggering major perturbations of Earth's C cycle and mass extinctions. A major C cycle perturbation involves readjustment of the outer physiochemical spheres of the Earth: the atmosphere, hydrosphere, and lithosphere; and by necessity, the biosphere. A greenhouse, one manifestation of a major C cycle perturbation, is the most dangerous natural phenomenon that life on Earth can experience. Greenhouse conditions existed during the KT mass extinctions of 65 m.y. ago, and the Pleistocene-Holocene (P-H) mammalian extinctions of 10,000-12,000 yr ago. Coupling climatology to reproductive physiology via effects of ambient air temperature upon uterine blood flow to developing embryos accounts for the extinctions via established physiological principles.

Mclean, D. M.↗