The Experts below are selected from a list of 32682 Experts worldwide ranked by ideXlab platform
Chris Hayman - One of the best experts on this subject based on the ideXlab platform.
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thermal conversion of elephant grass pennisetum purpureum schum to bio gas bio oil and charcoal
Bioresource Technology, 2008Co-Authors: Vladimir Strezov, Tim Evans, Chris HaymanAbstract:Abstract Elephant grass is an abundant, fast growing plant with significant potential as a renewable energy source and for conversion to Higher calorific value fuels. This work investigates thermal conversion of elephant grass to bio-gas, bio-oil and charcoal under two heating rates of 10 and 50 °C/min. The energy required to pyrolyse elephant grass was evaluated using computer aided thermal analysis technique, while composition of the resultant bio-gas and bio-oil products were monitored with gas chromatographic and mass spectroscopic techniques. At 500 °C, the bio-gas compounds consisted primarily of CO 2 and CO with small amounts of methane and Higher Hydrocarbon compounds. The heat of combustion of the bio-gas compounds was estimated to be 3.7–7.4 times Higher than the heat required to pyrolyse elephant grass under both heating rates, which confirms that the pyrolysis process can be self-maintained. Faster heating rate was found to increase the amount of liquid products by 10%, while charcoal yields remained almost the same at 30%. The bio-oil mainly consisted of organic acids, phthalate esters, benzene compounds and amides. The amount of organic acids and benzene compounds were significantly reduced at 50 °C/min, while the yields of phthalate esters and naphthalene compounds increased. The difference in bio-oil composition with increased heating rate is believed to be associated with the reduction of the secondary reactions of pyrolysis, which are more pronounced under lower heating rate.
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thermal conversion of elephant grass pennisetum purpureum schum to bio gas bio oil and charcoal
Bioresource Technology, 2008Co-Authors: Vladimir Strezov, Tim Evans, Chris HaymanAbstract:Elephant grass is an abundant, fast growing plant with significant potential as a renewable energy source and for conversion to Higher calorific value fuels. This work investigates thermal conversion of elephant grass to bio-gas, bio-oil and charcoal under two heating rates of 10 and 50 degrees C/min. The energy required to pyrolyse elephant grass was evaluated using computer aided thermal analysis technique, while composition of the resultant bio-gas and bio-oil products were monitored with gas chromatographic and mass spectroscopic techniques. At 500 degrees C, the bio-gas compounds consisted primarily of CO2 and CO with small amounts of methane and Higher Hydrocarbon compounds. The heat of combustion of the bio-gas compounds was estimated to be 3.7-7.4 times Higher than the heat required to pyrolyse elephant grass under both heating rates, which confirms that the pyrolysis process can be self-maintained. Faster heating rate was found to increase the amount of liquid products by 10%, while charcoal yields remained almost the same at 30%. The bio-oil mainly consisted of organic acids, phthalate esters, benzene compounds and amides. The amount of organic acids and benzene compounds were significantly reduced at 50 degrees C/min, while the yields of phthalate esters and naphthalene compounds increased. The difference in bio-oil composition with increased heating rate is believed to be associated with the reduction of the secondary reactions of pyrolysis, which are more pronounced under lower heating rate.
G J Roelofs - One of the best experts on this subject based on the ideXlab platform.
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impact of aircraft nox emissions on tropospheric ozone calculated with a chemistry general circulation model sensitivity to Higher Hydrocarbon chemistry
Journal of Geophysical Research, 2002Co-Authors: A S Kentarchos, G J RoelofsAbstract:[1] A three-dimensional chemistry-general circulation model has been employed to estimate the impact of current aircraft NOx emissions on tropospheric ozone. The model contains a representation of Higher Hydrocarbon chemistry, implemented by means of the Carbon Bond Mechanism 4 (CBM4), in order to investigate the potential effect of Higher Hydrocarbons on aircraft-induced ozone changes. Aircraft NOx emissions increase background NOX (= NO + NO2 + NO3 + 2N2O5 + HNO4) concentrations by 50–70 pptv in the upper troposphere over the Northern Hemisphere, and contribute up to 3 ppbv to upper tropospheric background ozone levels. When Higher Hydrocarbon chemistry is considered in the simulation, the aircraft-induced ozone perturbations are Higher by ∼12% during summer and the aircraft-induced ozone production efficiency per NOx molecule increases by ∼20%, when compared to a simulation without Higher Hydrocarbon chemistry.
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tropospheric ozone simulation with a chemistry general circulation model influence of Higher Hydrocarbon chemistry
Journal of Geophysical Research, 2000Co-Authors: G J Roelofs, Jos LelieveldAbstract:We present an improved version of the global chemistry-general circulation model of Roelofs and Lelieveld [1997]. The major model improvement is the representation of Higher Hydrocarbon chemistry, implemented by means of the Carbon Bond Mechanism 4 (CBM-4). Simulated tropospheric ozone concentrations at remote locations, which agreed well with observations in the previous model version, are not affected much by the chemistry of Higher Hydrocarbons. However, ozone formation in the polluted boundary layer is significantly enhanced, resulting in a more realistic simulation of surface ozone in regions such as North America, Europe, and Southeast Asia. Our model simulates a net global tropospheric ozone production of 73 Tg yr−1 when Higher Hydrocarbon chemistry is considered, and -36 Tg yr−1 without Higher Hydrocarbon chemistry. The simulated seasonality of surface CO agrees well with observations. However, the southern hemispheric maximum for O3 and CO associated with biomass burning emissions is delayed by 1 month compared to the observations, which demonstrates the need for a better representation of biomass burning emissions. Simulated peroxyacetyl nitrate (PAN) concentrations agree well with observed values, although the variability is underestimated. OH decreases strongly in the continental boundary layer due to its reaction with Higher Hydrocarbons. However, this is almost compensated by an increase of OH over oceans in the lower half of the troposphere. Consideration of Higher Hydrocarbon chemistry decreases the global annual tropospheric OH concentration by about 8% compared to a background tropospheric chemistry scheme. Further, the radiative forcing by anthropogenically increased tropospheric ozone on the northern hemisphere increases, especially in July. The forcing also increases on the southern hemisphere where biomass burning emissions produce tropospheric ozone, except between December and June, that is, outside the biomass burning season, when ozone formation is suppressed due to formation of PAN and MPAN from isoprene oxidation. Globally and annually averaged, the forcing increases only by a few percent due to Higher Hydrocarbon chemistry.
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distribution and budget of o3 in the troposphere calculated with a chemistry general circulation model
Journal of Geophysical Research, 1995Co-Authors: G J Roelofs, Jos LelieveldAbstract:We present results of global tropospheric chemistry simulations with the coupled chemistry/atmospheric general circulation model ECHAM. Ultimately, the model will be used to study climate changes induced by anthropogenic influences on the chemistry of the atmosphere; meteorological parameters that are important for the chemistry, such as temperature, humidity, air motions, cloud and rain characteristics, and mixing processes are calculated on-line. The chemical part of the model describes background tropospheric CH4-CO-NOx-HOx photochemistry. Emissions of NO and CO, surface concentrations of CH4, and stratospheric concentrations of O3 and NOy are prescribed as boundary conditions. Calculations of the tropospheric O3 budget indicate that seasonal variabilities of the photochemical production and of injection from the stratosphere are represented realistically, although some aspects of the model still need improvement. Comparisons of calculated O3 surface concentrations and O3 profiles with available measurements show that the model reproduces O3 distributions in remote tropical and midlatitudinal sites. Also, the model matches typical profiles connected with deep convection in the Intertropical Convergence Zone (ITCZ). However, the model tends to underestimate O3 concentrations at the poles and in relatively polluted regions. These underestimates are caused by the poor representation of tropopause foldings in midlatitudes, which form a significant source of tropospheric O3 from the stratosphere, too weak transport to the poles, and the neglect of Higher Hydrocarbon chemistry. Also, mixing of polluted continental boundary layer air into the free troposphere may be underestimated. We discuss how these model deficiencies will be improved in the future.
Vladimir Strezov - One of the best experts on this subject based on the ideXlab platform.
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thermal conversion of elephant grass pennisetum purpureum schum to bio gas bio oil and charcoal
Bioresource Technology, 2008Co-Authors: Vladimir Strezov, Tim Evans, Chris HaymanAbstract:Abstract Elephant grass is an abundant, fast growing plant with significant potential as a renewable energy source and for conversion to Higher calorific value fuels. This work investigates thermal conversion of elephant grass to bio-gas, bio-oil and charcoal under two heating rates of 10 and 50 °C/min. The energy required to pyrolyse elephant grass was evaluated using computer aided thermal analysis technique, while composition of the resultant bio-gas and bio-oil products were monitored with gas chromatographic and mass spectroscopic techniques. At 500 °C, the bio-gas compounds consisted primarily of CO 2 and CO with small amounts of methane and Higher Hydrocarbon compounds. The heat of combustion of the bio-gas compounds was estimated to be 3.7–7.4 times Higher than the heat required to pyrolyse elephant grass under both heating rates, which confirms that the pyrolysis process can be self-maintained. Faster heating rate was found to increase the amount of liquid products by 10%, while charcoal yields remained almost the same at 30%. The bio-oil mainly consisted of organic acids, phthalate esters, benzene compounds and amides. The amount of organic acids and benzene compounds were significantly reduced at 50 °C/min, while the yields of phthalate esters and naphthalene compounds increased. The difference in bio-oil composition with increased heating rate is believed to be associated with the reduction of the secondary reactions of pyrolysis, which are more pronounced under lower heating rate.
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thermal conversion of elephant grass pennisetum purpureum schum to bio gas bio oil and charcoal
Bioresource Technology, 2008Co-Authors: Vladimir Strezov, Tim Evans, Chris HaymanAbstract:Elephant grass is an abundant, fast growing plant with significant potential as a renewable energy source and for conversion to Higher calorific value fuels. This work investigates thermal conversion of elephant grass to bio-gas, bio-oil and charcoal under two heating rates of 10 and 50 degrees C/min. The energy required to pyrolyse elephant grass was evaluated using computer aided thermal analysis technique, while composition of the resultant bio-gas and bio-oil products were monitored with gas chromatographic and mass spectroscopic techniques. At 500 degrees C, the bio-gas compounds consisted primarily of CO2 and CO with small amounts of methane and Higher Hydrocarbon compounds. The heat of combustion of the bio-gas compounds was estimated to be 3.7-7.4 times Higher than the heat required to pyrolyse elephant grass under both heating rates, which confirms that the pyrolysis process can be self-maintained. Faster heating rate was found to increase the amount of liquid products by 10%, while charcoal yields remained almost the same at 30%. The bio-oil mainly consisted of organic acids, phthalate esters, benzene compounds and amides. The amount of organic acids and benzene compounds were significantly reduced at 50 degrees C/min, while the yields of phthalate esters and naphthalene compounds increased. The difference in bio-oil composition with increased heating rate is believed to be associated with the reduction of the secondary reactions of pyrolysis, which are more pronounced under lower heating rate.
Kenneth Lee - One of the best experts on this subject based on the ideXlab platform.
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Hydrocarbon biodegradation by arctic sea ice and sub ice microbial communities during microcosm experiments northwest passage nunavut canada
FEMS Microbiology Ecology, 2016Co-Authors: Marieeve Garneau, Christine Michel, Guillaume Meisterhans, Nathalie Fortin, Thomas King, Charles W Greer, Kenneth LeeAbstract:The increasing accessibility to navigation and offshore oil exploration brings risks of Hydrocarbon releases in Arctic waters. Bioremediation of Hydrocarbons is a promising mitigation strategy but challenges remain, particularly due to low microbial metabolic rates in cold, ice-covered seas. Hydrocarbon degradation potential of ice-associated microbes collected from the Northwest Passage was investigated. Microcosm incubations were run for 15 days at -1.7°C with and without oil to determine the effects of Hydrocarbon exposure on microbial abundance, diversity and activity, and to estimate component-specific Hydrocarbon loss. Diversity was assessed with automated ribosomal intergenic spacer analysis and Ion Torrent 16S rRNA gene sequencing. Bacterial activity was measured by (3)H-leucine uptake rates. After incubation, sub-ice and sea-ice communities degraded 94% and 48% of the initial Hydrocarbons, respectively. Hydrocarbon exposure changed the composition of sea-ice and sub-ice communities; in sea-ice microcosms, Bacteroidetes (mainly Polaribacter) dominated whereas in sub-ice microcosms, the contribution of Epsilonproteobacteria increased, and that of Alphaproteobacteria and Bacteroidetes decreased. Sequencing data revealed a decline in diversity and increases in Colwellia and Moritella in oil-treated microcosms. Low concentration of dissolved organic matter (DOM) in sub-ice seawater may explain Higher Hydrocarbon degradation when compared to sea ice, where DOM was abundant and composed of labile exopolysaccharides.
Jos Lelieveld - One of the best experts on this subject based on the ideXlab platform.
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tropospheric ozone simulation with a chemistry general circulation model influence of Higher Hydrocarbon chemistry
Journal of Geophysical Research, 2000Co-Authors: G J Roelofs, Jos LelieveldAbstract:We present an improved version of the global chemistry-general circulation model of Roelofs and Lelieveld [1997]. The major model improvement is the representation of Higher Hydrocarbon chemistry, implemented by means of the Carbon Bond Mechanism 4 (CBM-4). Simulated tropospheric ozone concentrations at remote locations, which agreed well with observations in the previous model version, are not affected much by the chemistry of Higher Hydrocarbons. However, ozone formation in the polluted boundary layer is significantly enhanced, resulting in a more realistic simulation of surface ozone in regions such as North America, Europe, and Southeast Asia. Our model simulates a net global tropospheric ozone production of 73 Tg yr−1 when Higher Hydrocarbon chemistry is considered, and -36 Tg yr−1 without Higher Hydrocarbon chemistry. The simulated seasonality of surface CO agrees well with observations. However, the southern hemispheric maximum for O3 and CO associated with biomass burning emissions is delayed by 1 month compared to the observations, which demonstrates the need for a better representation of biomass burning emissions. Simulated peroxyacetyl nitrate (PAN) concentrations agree well with observed values, although the variability is underestimated. OH decreases strongly in the continental boundary layer due to its reaction with Higher Hydrocarbons. However, this is almost compensated by an increase of OH over oceans in the lower half of the troposphere. Consideration of Higher Hydrocarbon chemistry decreases the global annual tropospheric OH concentration by about 8% compared to a background tropospheric chemistry scheme. Further, the radiative forcing by anthropogenically increased tropospheric ozone on the northern hemisphere increases, especially in July. The forcing also increases on the southern hemisphere where biomass burning emissions produce tropospheric ozone, except between December and June, that is, outside the biomass burning season, when ozone formation is suppressed due to formation of PAN and MPAN from isoprene oxidation. Globally and annually averaged, the forcing increases only by a few percent due to Higher Hydrocarbon chemistry.
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distribution and budget of o3 in the troposphere calculated with a chemistry general circulation model
Journal of Geophysical Research, 1995Co-Authors: G J Roelofs, Jos LelieveldAbstract:We present results of global tropospheric chemistry simulations with the coupled chemistry/atmospheric general circulation model ECHAM. Ultimately, the model will be used to study climate changes induced by anthropogenic influences on the chemistry of the atmosphere; meteorological parameters that are important for the chemistry, such as temperature, humidity, air motions, cloud and rain characteristics, and mixing processes are calculated on-line. The chemical part of the model describes background tropospheric CH4-CO-NOx-HOx photochemistry. Emissions of NO and CO, surface concentrations of CH4, and stratospheric concentrations of O3 and NOy are prescribed as boundary conditions. Calculations of the tropospheric O3 budget indicate that seasonal variabilities of the photochemical production and of injection from the stratosphere are represented realistically, although some aspects of the model still need improvement. Comparisons of calculated O3 surface concentrations and O3 profiles with available measurements show that the model reproduces O3 distributions in remote tropical and midlatitudinal sites. Also, the model matches typical profiles connected with deep convection in the Intertropical Convergence Zone (ITCZ). However, the model tends to underestimate O3 concentrations at the poles and in relatively polluted regions. These underestimates are caused by the poor representation of tropopause foldings in midlatitudes, which form a significant source of tropospheric O3 from the stratosphere, too weak transport to the poles, and the neglect of Higher Hydrocarbon chemistry. Also, mixing of polluted continental boundary layer air into the free troposphere may be underestimated. We discuss how these model deficiencies will be improved in the future.