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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 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

An integrated analytical framework for quantifying the LCOE of waste-to-energy facilities for a range of greenhouse gas emissions policy and technical factors

This study presents a novel integrated method for considering the economics of waste-to-energy (WTE) facilities with priced greenhouse gas (GHG) emissions based upon technical and economic characteristics of the WTE facility, MSW stream, landfill alternative, and GHG emissions policy. The study demonstrates use of the formulation for six different policy scenarios and explores sensitivity of the results to ranges of certain technical parameters as found in existing literature. The study shows that details of the GHG emissions regulations have large impact on the levelized cost of energy (LCOE) of WTE and that GHG regulations can either increase or decrease the LCOE of WTE depending on policy choices regarding biogenic fractions from combusted waste and emissions from landfills. Important policy considerations are the fraction of the carbon emissions that are priced (i.e. all emissions versus only non-biogenic emissions), whether emissions credits are allowed due to reducing fugitive landfill gas emissions, whether biogenic carbon sequestration in landfills is credited against landfill emissions, and the effectiveness of the landfill gas recovery system where waste would otherwise have been buried. The default landfill gas recovery system effectiveness assumed by much of the industry yields GHG offsets that are very close to the direct non-biogenic GHG emissions from a WTE facility, meaning that small changes in the recovery effectiveness cause relatively larger changes in the emissions factor of the WTE facility. Finally, the economics of WTE are dependent on the MSW stream composition, with paper and wood being advantageous, metal and glass being disadvantageous, and plastics, food, and yard waste being either advantageous or disadvantageous depending upon the avoided tipping fee and the GHG emissions price.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2011

ARCADE 2 OBSERVATIONS OF GALACTIC RADIO EMISSION

We use absolutely calibrated data from the ARCADE 2 flight in 2006 July to model Galactic emission at frequencies 3, 8, and 10 GHz. The spatial structure in the data is consistent with a superposition of free-free and synchrotron emission. Emission with spatial morphology traced by the Haslam 408 MHz survey has spectral index {beta}{sub synch} = -2.5 {+-} 0.1, with free-free emission contributing 0.10 {+-} 0.01 of the total Galactic plane emission in the lowest ARCADE 2 band at 3.15 GHz. We estimate the total Galactic emission toward the polar caps using either a simple plane-parallel model with csc |b| dependence or a model of high-latitude radio emission traced by the COBE/FIRAS map of C II emission. Both methods are consistent with a single power law over the frequency range 22 MHz to 10 GHz, with total Galactic emission toward the north polar cap T{sub Gal} = 10.12 {+-} 0.90 K and spectral index {beta} = -2.55 {+-} 0.03 at reference frequency 0.31 GHz. Emission associated with the plane-parallel structure accounts for only 30% of the observed high-latitude sky temperature, with the residual in either a Galactic halo or an isotropic extragalactic background. The well-calibrated ARCADE 2 maps provide a new test for spinning dust emission, based on the integrated intensity of emission from the Galactic plane instead of cross-correlations with the thermal dust spatial morphology. The Galactic plane intensity measured by ARCADE 2 is fainter than predicted by models without spinning dust and is consistent with spinning dust contributing 0.4 {+-} 0.1 of the Galactic plane emission at 23 GHz.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2014

Origin of multi-band emission from the microquasar Cygnus X-1

We study the origin of non-thermal emissions from the Galactic black hole X-ray binary Cygnus X-1, which is a confirmed high-mass microquasar. By analogy with the methods used in studies of active galactic nuclei, we propose a two-dimensional, time-dependent radiation model from the microquasar Cygnus X-1. In this model, the evolution equation for relativistic electrons in a conical jet are numerically solved by including escape, adiabatic, and various radiative losses. The radiative processes involved are synchrotron emission, its self-Compton scattering, and inverse Compton scatterings of an accretion disk and its surrounding stellar companion. This model also includes an electromagnetic cascade process of an anisotropic γ-γ interaction. We study the spectral properties of electron evolution and its emission spectral characteristic at different heights of the emission region located in the jet. We find that radio data from Cygnus X-1 are reproduced by the synchrotron emission, the Fermi Large Area Telescope measurements by the synchrotron emission and Comptonization of photons of the stellar companion, and the TeV band emission fluxes by the Comptonization of the stellar photons. Our results show the following. (1) The radio emission region extends from the binary system scales to the termination of the jet. (2) The GeV band emissions should originate from the distance close to the binary system scales. (3) The TeV band emissions could be inside the binary system, and these emissions could be probed by the upcoming Cherenkov Telescope Array. (4) The MeV tail emissions, which produce a strongly linearly polarized signal, are emitted inside the binary system. The location of the emissions is very close to the inner region of the jet.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2016

A Global Catalogue of Large SO2 Sources and Emissions Derived from the Ozone Monitoring Instrument

Sulfur dioxide (SO2) measurements from the Ozone Monitoring Instrument (OMI) satellite sensor processed with the new principal component analysis (PCA) algorithm were used to detect large point emission sources or clusters of sources. The total of 491 continuously emitting point sources releasing from about 30 kt yr(exp -1) to more than 4000 kt yr(exp -1) of SO2 per year have been identified and grouped by country and by primary source origin: volcanoes (76 sources); power plants (297); smelters (53); and sources related to the oil and gas industry (65). The sources were identified using different methods, including through OMI measurements themselves applied to a new emission detection algorithm, and their evolution during the 2005- 2014 period was traced by estimating annual emissions from each source. For volcanic sources, the study focused on continuous degassing, and emissions from explosive eruptions were excluded. Emissions from degassing volcanic sources were measured, many for the first time, and collectively they account for about 30% of total SO2 emissions estimated from OMI measurements, but that fraction has increased in recent years given that cumulative global emissions from power plants and smelters are declining while emissions from oil and gas industry remained nearly constant. Anthropogenic emissions from the USA declined by 80% over the 2005-2014 period as did emissions from western and central Europe, whereas emissions from India nearly doubled, and emissions from other large SO2-emitting regions (South Africa, Russia, Mexico, and the Middle East) remained fairly constant. In total, OMI-based estimates account for about a half of total reported anthropogenic SO2 emissions; the remaining half is likely related to sources emitting less than 30 kt yr(exp -1) and not detected by OMI.

Emissions↗
DOE OSTI2018

Evolution, Current State of the Art, and Interpretation of Aircraft-Based Methane Emission Quantification at the Natural Gas Basin-Level

Accurately quantifying methane (CH4) emissions from the oil and gas (O&G) industry is challenging given the existence of many potential emission sources, differences in industry practices and regulations, and often incomplete or out-of-date activity data. It is thus important to regularly assess emission inventories and support improvements by deriving independent estimates using state-of-the-science approaches. Recent research has provided CH4 emission estimates from the O&G supply chains based on different measurement techniques at multiple spatio-temporal scales. Natural gas basin-scale aircraft-based atmospheric measurements indicate greater CH4 emissions than emission inventories based on up-scaling of component-/facility-level emission measurements from a relatively small sample size. Here we present results from a coordinated field study that compares concurrent CH4 emission measurements using different techniques and scales to better understand the strengths and weaknesses of each approach, with a focus on the aircraft-based estimation method. We describe the importance of (i) decades of measurement technology development, (ii) experience in designing measurement sampling strategies and aligning system boundaries, and (Hi) properly interpreting CH4 emission estimates for successfully reconciling aircraft-based measurements with emission inventories and for identifying CH4 emission mitigation potential. We illustrate that aircraft-based top-down estimates represent a brief snapshot of total basin-level CH4 emissions. Thus, a high spatio-temporally resolved bottom-up emission inventory is needed to identify key CH4 sources (including episodic sources) at the process level. While this paper provides a brief overview of the overall study design and findings, its focus is on the implementation of the aircraft measurements and its interpretation and results. A separate paper describes in more detail the overall organizational structure of the study as well as the study implications from an industry perspective.

03 NATURAL GAS↗
DOE OSTI2014

Direct observation of electron emission from the grain boundaries of chemical vapour deposition diamond films by tunneling atomic force microscopy

The emission of electrons from diamond in vacuum occurs readily as a result of the negative electron affinity of the hydrogenated surface due to features with nanoscale dimensions, which can concentrate electric fields high enough to induce electron emission from them. Electrons can be emitted as a result of an applied electric field (field emission) with possible uses in displays or cold-cathode devices. Alternatively, electrons can be emitted simply by heating the diamond in vacuum to temperatures as low as 350 °C (thermionic emission), and this may find applications in solar energy generation or energy harvesting devices. Electron emission studies usually use doped polycrystalline diamond films deposited onto Si or metallic substrates by chemical vapor deposition, and these films have a rough, faceted morphology on the micron or nanometer scale. Electron emission is often improved by patterning the diamond surface into sharp points or needles, the idea being that the field lines concentrate at the points lowering the barrier for electron emission. However, there is little direct evidence that electrons are emitted from these sharp tips. The few reports in the literature that have studied the emission sites suggested that emission came from the grain boundaries and not the protruding regions. We now present direct observation of the emission sites over a large area of polycrystalline diamond using tunneling atomic force microscopy. We confirm that the emission current comes mostly from the grain boundaries, which is consistent with a model for emission in which the non-diamond phase is the source of electrons with a threshold that is determined by the surrounding hydrogenated diamond surface.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Evolution of anthropogenic and biomass burning emissions of air pollutants at global and regional scales during the 1980-2010 period

Several different inventories of global and regional anthropogenic and biomass burning emissions are assessed for the 1980-2010 period. The species considered in this study are carbon monoxide, nitrogen oxides, sulfur dioxide and black carbon. The inventories considered include the ACCMIP historical emissions developed in support of the simulations for the IPCC AR5 assessment. Emissions for 2005 and 2010 from the Representative Concentration Pathways (RCPs) are also included. Large discrepancies between the global and regional emissions are identified, which shows that there is still no consensus on the best estimates for surface emissions of atmospheric compounds. At the global scale, anthropogenic emissions of CO, NOx and SO2 show the best agreement in most years. The agreement is low for BC emissions, particularly in the period prior to 2000. The best consensus is for NOx emissions for all periods and all regions, except for China where emissions in 1980 and 1990 need to be better defined. Emissions of CO need a better quantification in the USA for all periods; in Central Europe, the evolution of emissions during the past two decades needs to be better determined. The agreement between the different SO2 emissions datasets is rather good for the USA, but better quantification is needed elsewhere, particularly for Central Europe and China. The comparisons performed in this study show that the use of RCP8.5 for the extension of the ACCMIP inventory beyond 2000 is reasonable, until more global or regional estimates become available. Concerning biomass burning emissions, most inventories agree within 50-80%, depending on the year and season. The large differences are due to differences in the estimates of burned areas from the different available products, as well as in the amount of biomass burnt.

09 BIOMASS FUELS↗
DOE OSTI2014

Greenhouse gas emissions from production chain of a cigarette manufacturing industry in Pakistan

This study quantified greenhouse gas (GHG) emissions from the Pakistan Tobacco Company (PTC) production using a life cycle approach. The PTC production chain comprises of two phases: agricultural activities (Phase I) and industrial activities (Phase II). Data related to agricultural and industrial activities of PTC production chain were collected through questionnaire survey from tobacco growers and records from PTC manufacturing units. The results showed that total GHG emissions from PTC production chain were 44,965, 42,875, and 43,839 tCO{sub 2}e respectively in 2009, 2010, and 2011. Among the agricultural activities, firewood burning for tobacco curing accounted for about 3117, 3565, and 3264 tCO{sub 2}e, fertilizer application accounted for 754, 3251, and 4761 tCO{sub 2}e in 2009, 2010, and 2011, respectively. Among the industrial activities, fossil fuels consumption in stationary sources accounted for 15,582, 12,733, and 13,203 tCO{sub 2}e, fossil fuels used in mobile sources contributed to 2693, 3038, and 3260 tCO{sub 2}e, and purchased electricity consumed resulted in 15,177, 13,556, and 11,380 tCO{sub 2}e in 2009, 2010, and 2011, respectively. The GHG emissions related to the transportation of raw materials and processed tobacco amounted to 6800, 6301, and 7317 respectively in 2009, 2010, and 2011. GHG emissions from energy use in the industrial activities constituted the largest emissions (i.e., over 80%) of GHG emissions as PTC relies on fossil fuels and fossil fuel based electrical power in industrial processes. The total emissions of carbon footprint (CFP) from PTC production were 0.647 tCO{sub 2}e per million cigarettes produced in 2009, 0.675 tCO{sub 2}e per million cigarettes in 2010 and 0.59 tCO{sub 2}e per million cigarettes in 2011. Potential strategies for GHG emissions reductions for PTC production chain include energy efficiency, reducing reliance on fossil fuels in non-mobile sources, adoption of renewable fuels including solar energy, energy from crop residues, and promotion of organic fertilizers. - Highlights: • We quantified greenhouse gas (GHG) emissions from the Pakistan Tobacco Company (PTC). • PTC production chain comprises of two phases: agricultural and industrial activities. • GHG emissions accounts to 44,965, 42,875 and 43,839 tCO{sub 2}e in 2009, 2010, and 2011, respectively. • GHG emissions from energy use in the industrial activities constituted the largest emissions i.e. 80%. • Implications for GHG emissions mitigation strategies for PTC are also discussed in detail.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Nitrous oxide and methane emissions and nitrous oxide isotopic composition from waste incineration in Switzerland

Highlights: • N{sub 2}O emissions from waste incineration with SNCR NO{sub x} removal are 51.5 ± 10.6 g t{sup −1}. • This is significantly lower than the reported Swiss emission factor of 120 g t{sup −1} (FOEN, 2013). • N{sub 2}O contributes <0.3% and ≈2.5% of GHG emissions from SCR and SNCR plants. • Measured isotopic SP of 17.7‰ is likely characteristic for N{sub 2}O emissions from SNCR. • CH{sub 4} emitted by waste incineration is negligible, contributing <0.01% to total GHGs. - Abstract: Solid waste incineration accounts for a growing proportion of waste disposal in both developed and developing countries, therefore it is important to constrain emissions of greenhouse gases from these facilities. At five Swiss waste incineration facilities with grate firing, emission factors for N{sub 2}O and CH{sub 4} were determined based on measurements of representative flue gas samples, which were collected in Tedlar bags over a one year period (September 2010–August 2011) and analysed with FTIR spectroscopy. All five plants burn a mixture of household and industrial waste, and two of the plants employ NO{sub x} removal through selective non-catalytic reduction (SNCR) while three plants use selective catalytic reduction (SCR) for NO{sub x} removal. N{sub 2}O emissions from incineration plants with NO{sub x} removal through selective catalytic reduction were 4.3 ± 4.0 g N{sub 2}O tonne{sup −1} waste (wet) (hereafter abbreviated as t{sup −1}) (0.4 ± 0.4 g N{sub 2}O GJ{sup −1}), ten times lower than from plants with selective non-catalytic reduction (51.5 ± 10.6 g N{sub 2}O t{sup −1}; 4.5 ± 0.9 g N{sub 2}O GJ{sup −1}). These emission factors, which are much lower than the value of 120 g N{sub 2}O t{sup −1} (10.4 g N{sub 2}O GJ{sup −1}) used in the 2013 Swiss national greenhouse gas emission inventory, have been implemented in the most recent Swiss emission inventory. In addition, the isotopic composition of N{sub 2}O emitted from the two plants with SNCR, which had considerable N{sub 2}O emissions, was measured using quantum cascade laser spectroscopy. The isotopic site preference of N{sub 2}O – the enrichment of {sup 14}N{sup 15}NO relative to {sup 15}N{sup 14}NO – was found to be 17.6 ± 0.8‰, with no significant difference between the two plants. Comparison to previous studies suggests SP of 17–19‰ may be characteristic for N{sub 2}O produced from SNCR. Methane emissions were found to be insignificant, with a maximum emission factor of 2.5 ± 5.6 g CH{sub 4} t{sup −1} (0.2 ± 0.5 g CH{sub 4} GJ{sup −1}), which is expected due to high incinerator temperatures and efficient combustion.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2011

Spatial Relationships of Sector-Specific Fossil-fuel CO2 Emissions in the United States

Quantification of the spatial distribution of sector-specific fossil fuel CO2 emissions provides strategic information to public and private decision-makers on climate change mitigation options and can provide critical constraints to carbon budget studies being performed at the national to urban scales. This study analyzes the spatial distribution and spatial drivers of total and sectoral fossil fuel CO2 emissions at the state and county levels in the United States. The spatial patterns of absolute versus per capita fossil fuel CO2 emissions differ substantially and these differences are sector-specific. Area-based sources such as those in the residential and commercial sectors are driven by a combination of population and surface temperature with per capita emissions largest in the northern latitudes and continental interior. Emission sources associated with large individual manufacturing or electricity producing facilities are heterogeneously distributed in both absolute and per capita metrics. The relationship between surface temperature and sectoral emissions suggests that the increased electricity consumption due to space cooling requirements under a warmer climate may outweigh the savings generated by lessened space heating. Spatial cluster analysis of fossil fuel CO2 emissions confirms that counties with high (low) CO2 emissions tend to be clustered close to other counties with high (low) CO2 emissions and some of the spatial clustering extends to multi-state spatial domains. This is particularly true for the residential and transportation sectors, suggesting that emissions mitigation policy might best be approached from the regional or multi-state perspective. Our findings underscore the potential for geographically focused, sector-specific emissions mitigation strategies and the importance of accurate spatial distribution of emitting sources when combined with atmospheric monitoring via aircraft, satellite and in situ measurements. Keywords: Fossil-fuel; Carbon dioxide emissions; Sectoral; Spatial cluster; Emissions mitigation policy

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Land-use change and greenhouse gas emissions from corn and cellulosic ethanol

Background: The greenhouse gas (GHG) emissions that may accompany land-use change (LUC) from increased biofuel feedstock production are a source of debate in the discussion of drawbacks and advantages of biofuels. Estimates of LUC GHG emissions focus mainly on corn ethanol and vary widely. Increasing the understanding of LUC GHG impacts associated with both corn and cellulosic ethanol will inform the on-going debate concerning their magnitudes and sources of variability. Results: In our study, we estimate LUC GHG emissions for ethanol from four feedstocks: corn, corn stover, switchgrass, and miscanthus. We use new computable general equilibrium (CGE) results for worldwide LUC. U.S. domestic carbon emission factors are from state-level modelling with a surrogate CENTURY model and U.S. Forest Service data. This paper investigates the effect of several key domestic lands carbon content modelling parameters on LUC GHG emissions. International carbon emission factors are from the Woods Hole Research Center. LUC GHG emissions are calculated from these LUCs and carbon content data with Argonne National Laboratory’s Carbon Calculator for Land Use Change from Biofuels Production (CCLUB) model. Our results indicate that miscanthus and corn ethanol have the lowest (-10 g CO2e/MJ) and highest (7.6 g CO2e/MJ) LUC GHG emissions under base case modelling assumptions. The results for corn ethanol are lower than corresponding results from previous studies. Switchgrass ethanol base case results (2.8 g CO2e/MJ) were the most influenced by assumptions regarding converted forestlands and the fate of carbon in harvested wood products. They are greater than miscanthus LUC GHG emissions because switchgrass is a lower-yielding crop. Finally, LUC GHG emissions for corn stover are essentially negligible and insensitive to changes in model assumptions. Conclusions: This research provides new insight into the influence of key carbon content modelling variables on LUC GHG emissions associated with the four bioethanol pathways we examined. Our results indicate that LUC GHG emissions may have a smaller contribution to the overall biofuel life cycle than previously thought. Additionally, they highlight the need for future advances in LUC GHG emissions estimation including improvements to CGE models and aboveground and belowground carbon content data.

09 BIOMASS FUELS↗
DOE OSTI2021

Emission Inventories from Natural Gas Storage Facilities using Regional Frequency Comb Laser Monitoring and Aircraft Flyovers. Final Report

The project centers around a ground-based regional methane sensor developed by the CU/NIST team members under the DOE ARPA-E MONITOR program, and sophisticated aircraft measurement techniques developed by the UCD/Scientific Aviation team (responsible for a recent Science publication quantifying the Aliso Canyon storage field release). The dual frequency-comb spectrometer is an invisible, eye-safe laser capable of measuring atmospheric methane concentrations along beam paths 1+ miles in length with high precision and stability (<1 ppb methane over 1 mile). The CU/NIST team has developed a unique approach to using a single, central spectrometer to locate and size methane emissions as small as 6 scfh from specific gas field structures within the 1+ mile range of the laser. Deployment involves the stationing of small cubic mirrors at strategic locations across the gas storage site. The mirrors direct light from the spectrometer back to a detector, where methane concentrations are recorded based on light absorption at specific wavelengths. The measurements are coupled with high resolution gas transport models based on meteorological measurements (wind, etc.) to determine the precise location and emission rate of methane sources. The calibration-free and continuous nature of dual frequency-comb spectrometer measurements means that a large area can be monitored continuously for temporal variability of emissions over long periods of time. The aircraft measurements involve spiral flights around storage facilities with a sensitive ethane/methane measurement package. Upwind/downwind concentration comparisons and wind data provide total facility emissions data. During this project, a new micrometeorological package was integrated onto the Scientific Aviation aircraft to provide even greater emissions quantification capability. In this project, the ground-based measurement system was deployed for 11 months (to capture seasonal variability) at a West Coast storage facility, together with a campaign of twice monthly aircraft total facility emissions flights. The data from these two modalities was combined to quantify the methane emissions from the facility with first-of-its-kind temporal and spatial detail. Concurrent with this deployment, the aircraft team performed flights to quantify emissions at a wider array of previously un-surveyed storage sites. The ground-based measurement system was then moved to an additional site of differing total storage and delivery capacity. Aircraft mass balance flights continued, repeatedly surveying (twice monthly) this site, as well as surveying a large number of previously un-assessed sites spanning a variety of size, reservoir type and age. Assessment of ground-based, temporally and spatially detailed methane emissions information alongside aircraft-derived methane total facility emissions information led to an improved understanding of emissions, relevant for inventories of the natural gas storage sector. In particular, this work provided temporal detail (seasonal of emissions and frequency of leaks) to stakeholders and personnel responsible for updates to the EPA’s GHGI. The impact of the proposed work has been a dramatic improvement in the temporal, spatial, and site- and type- specific detail and quantification of emissions inventories for the natural gas storage sector. This work directly benefits the EPA’s GHGI, directly ameliorates the environmental impacts and public health and safety of the natural gas storage sector, and aids policymakers and industry to make sound choices with respect to management and regulation.

03 NATURAL GAS↗
DOE OSTI2013

Field Emission Studies Toward Improving the Performance of DC High Voltage Photoelectron Guns

Field emission is the main mechanism that prevents DC high voltage photoemission electron guns from operating at the very high bias voltages required to produce low emittance beams. Gas conditioning is shown to eliminate field emission from cathode electrodes used inside DC high voltage photoelectron guns. Measurements and simulation results indicate that gas conditioning eliminates field emission from cathode electrodes via two mechanisms: sputtering and implantation, with the benefits of implantation reversed by heating the electrode. The field emission characteristics of 5 stainless steel electrodes varied significantly upon the initial application of voltage but improved to nearly the same level after helium and krypton gas conditioning, exhibiting less than 10 pA field emission at - 225kV bias voltage with a 50 mm cathode/anode gap, corresponding to a field strength ? 13 MV/m. Field emission could be reduced with either krypton or helium, but there were conditions related to gas choice, voltage and field strength that were more favorable than others. The field emission characteristics of niobium electrodes were compared to those of stainless steel electrodes using a DC high voltage field emission test apparatus. Out of 8 electrodes (6 niobium and 2 stainless steel), the best niobium electrode performed better than the best stainless steel electrodes. Large grain niobium exhibited no measurable field emission (< 10 pA) at 225 kV with 20 mm cathode/anode gap, corresponding to a field strength of 18.7 MV/m. Surface evaluation of all electrodes suggested no correlation between the surface roughness and the field emission current. Removing surface particulate contaminations and protrusions using an effective polishing and cleaning technique helps to prevent field emission. Mechanical polishing using silicon carbide paper and diamond paste is a common method of obtaining a mirror like surface finish on the cathode electrodes. However, it sometimes results rolled-over tips and embedded contamination. A different polishing technique was considered: electropolishing. Three stainless steel cathode electrodes with different initial surface roughness were electropolished by a commercial vendor, and evaluated inside a high voltage test stand. They exhibited less field emission than the diamond paste polished electrodes at the initial application of high voltage; but they were less receptive to ion implantation, which is a beneficial aspect of gas conditioning that serves to increase the work function of the cathode surface. Ultimately, the electropolished electrodes exhibited more field emission than diamond-paste polished electrodes.

Bastaninejad, Mahzad↗
DOE OSTI2016

Methanol and isoprene emissions from the fast growing tropical pioneer species <i>Vismia guianensis</i> (Aubl.) Pers. (Hypericaceae) in the central Amazon forest

Abstract. Isoprene (Is) emissions by plants represent a loss of carbon and energy resources leading to the initial hypothesis that fast growing pioneer species in secondary tropical forests allocate carbon primarily to growth at the expense of isoprenoid defenses. In this study, we quantified leaf isoprene and methanol emissions from the abundant pantropical pioneer tree species Vismia guianensis and ambient isoprene concentrations above a diverse secondary forest in the central Amazon. As photosynthetically active radiation (PAR) was varied (0 to 3000 µmol m−2 s−1) under standard leaf temperature (30 °C), isoprene emissions from V. guianensis increased without saturation up to 80 nmol m−2 s−1. A nonlinear increase in isoprene emissions with respect to net photosynthesis (Pn) resulted in the fraction of Pn dedicated to isoprene emissions increasing with light intensity (up to 2 % of Pn). Emission responses to temperature under standard light conditions (PAR of 1000 µmol m−2 s−1) resulted in the classic uncoupling of isoprene emissions (Topt, iso > 40 °C) from net photosynthesis (Topt, Pn = 30.0–32.5 °C) with up to 7 % of Pn emitted as isoprene at 40 °C. Under standard environmental conditions of PAR and leaf temperature, young V. guianensis leaves showed high methanol emissions, low Pn, and low isoprene emissions. In contrast, mature leaves showed high Pn, high isoprene emissions, and low methanol emissions, highlighting the differential control of leaf phenology over methanol and isoprene emissions. High daytime ambient isoprene concentrations (11 ppbv) were observed above a secondary Amazon rainforest, suggesting that isoprene emissions are common among neotropical pioneer species. The results are not consistent with the initial hypothesis and support a functional role of methanol during leaf expansion and the establishment of photosynthetic machinery and a protective role of isoprene for photosynthesis during high temperature extremes regularly experienced in secondary rainforest ecosystems.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Methane and carbon dioxide emissions from 40 lakes along a north–south latitudinal transect in Alaska

Uncertainties in the magnitude and seasonality of various gas emission modes, particularly among different lake types, limit our ability to estimate methane (CH 4 ) and carbon dioxide (CO 2 ) emissions from northern lakes. Here we assessed the relationship between CH 4 and CO 2 emission modes in 40 lakes along a latitudinal transect in Alaska to lakes' physicochemical properties and geographic characteristics, including permafrost soil type surrounding lakes. Emission modes included direct ebullition, diffusion, storage flux, and a newly identified ice-bubble storage (IBS) flux. We found that all lakes were net sources of atmospheric CH 4 and CO 2 , but the climate warming impact of lake CH 4 emissions was 2 times higher than that of CO 2 . Ebullition and diffusion were the dominant modes of CH 4 and CO 2 emissions, respectively. IBS, ~10% of total annual CH 4 emissions, is the release to the atmosphere of seasonally ice-trapped bubbles when lake ice confining bubbles begins to melt in spring. IBS, which has not been explicitly accounted for in regional studies, increased the estimate of springtime emissions from our study lakes by 320%. Geographically, CH 4 emissions from stratified, mixotrophic interior Alaska thermokarst (thaw) lakes formed in icy, organic-rich yedoma permafrost soils were 6-fold higher than from non-yedoma lakes throughout the rest of Alaska. The relationship between CO 2 emissions and geographic parameters was weak, suggesting high variability among sources and sinks that regulate CO 2 emissions (e.g., catchment waters, pH equilibrium). Total CH 4 emission was correlated with concentrations of soluble reactive phosphorus and total nitrogen in lake water, Secchi depth, and lake area, with yedoma lakes having higher nutrient concentrations, shallower Secchi depth, and smaller lake areas. Our findings suggest that permafrost type plays important roles in determining CH 4 emissions from lakes by both supplying organic matter to methanogenesis directly from thawing permafrost and by enhancing nutrient availability to primary production, which can also fuel decomposition and methanogenesis.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2003

Emissions of Trace Gases and Particles from Two Ships in the Southern Atlantic Ocean

Measurements were made of the emissions of particles and gases from two diesel-powered ships in the southern Atlantic Ocean off the coast of Namibia. The measurements are used to derive emission factors from ships of three species not reported previously, namely, black carbon, accumulation-mode particles, and cloud condensation nuclei (CCN), as well as for carbon dioxide, carbon monoxide (CO), methane (CH4), non-methane hydrocarbons, sulfur dioxide (SO2), nitrogen oxides (NOx), and condensation nuclei. The effects of fuel grade and engine power on ship emissions are discussed. The emission factors are combined with fuel usage data to obtain estimates of global annual emissions of various particles and gases from ocean-going ships. Global emissions of black carbon, accumulation- mode particles, and CCN from ocean-going ships are estimated to be 19-26 Gg yr(sup -1), (4.4-6.1) x 10(exp 26) particles yr(sup -1), and (1.0-1.5) x l0(exp 26) particles yr(sup -1), respectively. Black carbon emissions from ocean-going ships are approximately 0.2% of total anthropogenic emissions. Emissions of NOx and SO2 from ocean-going ships are approximately 10-14% and approximately 3-4%, respectively, of the total emissions of these species from the burning of fossil fuels, and approximately 40% and approximately 70%, respectively, of the total emissions of these species from the burning of biomass. Global annual emissions of CO and CH4 from ocean-going ships are approximately 2% and approximately 2-5%, respectively, of natural oceanic emissions of these species.

Sinha, Parikhit↗
NASA NTRS2010

ARCADE 2 Observations of Galactic Radio Emission

We use absolutely calibrated data from the Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission (ARCADE 2) flight in July 2006 to model Galactic emission at frequencies 3, 8, and 10 GHz. The spatial structure in the data is consistent with a superposition of free-free and synchrotron emission. Emission with spatial morphology traced by the Haslam 408 MHz survey has spectral index beta_synch = -2.5 +/- 0.1, with free-free emission contributing 0.10 +/- 0.01 of the total Galactic plane emission in the lowest ARCADE 2 band at 3.15 GHz. We estimate the total Galactic emission toward the polar caps using either a simple plane-parallel model with csc|b| dependence or a model of high-latitude radio emission traced by the COBE/FIRAS map of CII emission. Both methods are consistent with a single power-law over the frequency range 22 MHz to 10 GHz, with total Galactic emission towards the north polar cap T_Gal = 0.498 +/- 0.028 K and spectral index beta = -2.55 +/- 0.03 at reference frequency 0.31 GHz. The well calibrated ARCADE 2 maps provide a new test for spinning dust emission, based on the integrated intensity of emission from the Galactic plane instead of cross-correlations with the thermal dust spatial morphology. The Galactic plane intensity measured by ARCADE 2 is fainter than predicted by models without spinning dust, and is consistent with spinning dust contributing 0.4 +/- 0.1 of the Galactic plane emission at 23 GHz.

Kogut, A.↗
NASA NTRS2017

Satellites May Underestimate Rice Residue and Associated Burning Emissions in Vietnam

In this study, we estimate rice residue, associated burning emissions, and compare results with existing emissions inventories employing a bottom-up approach. We first estimated field-level post-harvest rice residues, including separate fuel-loading factors for rice straw and rice stubble. Results suggested fuel-loading factors of 0.27 kg/sq m (+/-0.033), 0.61 kg/sq m (+/-0.076), and 0.88 kg/sq m (+/-0.083) for rice straw, stubble, and total post-harvest biomass, respectively. Using these factors, we quantified potential emissions from rice residue burning and compared our estimates with other studies. Our results suggest total rice residue burning emissions as 2.24 Gg PM2.5, 36.54 Gg CO and 567.79 Gg CO2 for Hanoi Province, which are significantly higher than earlier studies. We attribute our higher emission estimates to improved fuel-loading factors; moreover, we infer that some earlier studies relying on residue-to-product ratios could be underestimating rice residue emissions by more than a factor of 2.3 for Hanoi, Vietnam. Using the rice planted area data from the Vietnamese government, and combining our fuel-loading factors, we also estimated rice residue PM2.5 emissions for the entirety of Vietnam and compared these estimates with an existing all-sources emissions inventory, and the Global Fire Emissions Database (GFED). Results suggest 75.98 Gg of PM2.5 released from rice residue burning accounting for 12.8% of total emissions for Vietnam. The GFED database suggests 42.56 Gg PM2.5 from biomass burning with 5.62 Gg attributed to agricultural waste burning indicating satellite-based methods may be significantly underestimating emissions. Our results not only provide improved residue and emission estimates, but also highlight the need for emissions mitigation from rice residue burning.

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