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Sustainability is a topic that is becoming more and more important in energy production systems. Due to new energy policies, hydrogen is receiving increasing attention as a carbon-free energy carrier embedded in hybrid renewable energy systems (HRES). This paper presents a sustainability analysis of the HRES operation involving electrolytic hydrogen production and conversion to methane through Power-to-Methane (PtM). The analysis is based on day-ahead (DA) scheduling to accomplish the minimum HRES operating cost by comparing two PtM models: A simple rigid model with constant input/output efficiency without hydrogen storage and a linearised electrolyser and methane model with hydrogen storage. The subsequent analysis is conducted by adding heat and gas accumulators in the linearised PtM model to evaluate the added flexibility of these components. Based on the optimal DA programming solution, the three PtM representations are compared based on their respective operating costs and carbon dioxide emissions. The outcomes show that hydrogen into the HRES via a PtM process is not a direct sign of sustainability and that the environmental impact depends on the electricity source provided by the electrolyser. Therefore, this paper highlights that the growth of RES and the integration of PtM should go in synergy and deducting that a more accurate model is required to understand the potential of PtM.

This work describes the gasification of carbon produced during the pyrolysis of methane. Carbon was deposited on nonporous a-Al2O3 at temperatures ranging between 950 and 1150 ?. The time a-Al2O3 was in contact with methane was varied between 60 and 8400 s. Gasification tests were performed in the range of 1000 to 1100 ? and steam, CO2 and air were used as oxidizer.& nbsp;It was observed that the gasification rate cannot be described by only parameters related to the gasification conditions (temperature, pressure, gas composition). In fact, it became clear that information about the carbon is needed in the gasification rate equation. The H/C ratio and the peak oxidation temperature, as reactivity measures, turned out not to relate uniquely to the gasification rate and are thus not suited as completing parameters. However, it was possible to relate the gasification reactivity of the carbon to the pyrolysis conditions (temperature, contact time between a-Al2O3 and CH4) under which it was produced. After parameterization of the thus obtained rate equation using data obtained in a single particle reactor, an adequate prediction on the gasification of carbon deposited by pyrolysis of methane in a fixed could be made. The developed method is therefore a suitable way of predicting gasification rates for reactor design purposes.

Global construction industry has a huge influence on world primary energy consumption, spending, and greenhouse gas (GHGs) emissions. To better understand these factors for mass timber construction, this work quantified the life cycle environmental and economic performances of a high-rise mass timber building in U.S. Pacific Northwest region through the use of life-cycle assessment (LCA) and life-cycle cost analysis (LCCA). Using the TRACI impact category method, the cradle-to-grave LCA results showed better environmental performances for the mass timber building relative to conventional concrete building, with 3153 kg CO2-eq per m2 floor area compared to 3203 CO2-eq per m2 floor area, respectively. Over 90% of GHGs emissions occur at the operational stage with a 60-year study period. The end-of-life recycling of mass timber could provide carbon offset of 364 kg CO2-eq per m2 floor that lowers the GHG emissions of the mass timber building to a total 12% lower GHGs emissions than concrete building. The LCCA results showed that mass timber building had total life cycle cost of $3976 per m2 floor area that was 9.6% higher than concrete building, driven mainly by upfront construction costs related to the mass timber material. Uncertainty analysis of mass timber product pricing provided a pathway for builders to make mass timber buildings cost competitive. The integration of LCA and LCCA on mass timber building study can contribute more information to the decision makers such as building developers and policymakers.

The molecular structure of the 8-hydroxyquinoline&ndash, bis (2-phenylpyridyl) iridium (IrQ(ppy)2) dual emitter organometallic compound is determined based on detailed 1D and 2D nuclear magnetic resonance (NMR), to identify metal-ligands coordination, isomerization and chemical yield of the desired compound. Meanwhile, the extended X-ray absorption fine structure (EXAFS) was used to determine the interatomic distances around the iridium ion. From the NMR results, this compound IrQ(ppy)2 exhibits a trans isomerization with a distribution of coordinated N-atoms in a similar way to facial Ir(ppy)3. The EXAFS measurements confirm the structural model of the IrQ(ppy)2 compound where the oxygen atoms from the quinoline ligands induce the splitting of the next-nearest neighboring C in the second shell of the Ir3+ ions. The high-performance liquid chromatography (HPLC), as a part of the detailed molecular analysis, confirms the purity of the desired IrQ(ppy)2 organometallic compound as being more than 95%, together with the progress of the chemical reactions towards the final compound. The theoretical model of the IrQ(ppy)2, concerning the expected bond lengths, is compared with the structural model from the EXAFS and XRD measurements.

The molecular structure of the 8-hydroxyquinoline–bis (2-phenylpyridyl) iridium (IrQ(ppy)2) dual emitter organometallic compound is determined based on detailed 1D and 2D nuclear magnetic resonance (NMR), to identify metal-ligands coordination, isomerization and chemical yield of the desired compound. Meanwhile, the extended X-ray absorption fine structure (EXAFS) was used to determine the interatomic distances around the iridium ion. From the NMR results, this compound IrQ(ppy)2 exhibits a trans isomerization with a distribution of coordinated N-atoms in a similar way to facial Ir(ppy)3. The EXAFS measurements confirm the structural model of the IrQ(ppy)2 compound where the oxygen atoms from the quinoline ligands induce the splitting of the next-nearest neighboring C in the second shell of the Ir3+ ions. The high-performance liquid chromatography (HPLC), as a part of the detailed molecular analysis, confirms the purity of the desired IrQ(ppy)2 organometallic compound as being more than 95%, together with the progress of the chemical reactions towards the final compound. The theoretical model of the IrQ(ppy)2, concerning the expected bond lengths, is compared with the structural model from the EXAFS and XRD measurements.

The paper presents the results of calculations of silicon carbide content in residue samples of carbothermic reduction of SiO2 after 6 hours. The content of SiC was calculated in two ways. The first from mass balance equations of samples and analysis of oxygen content. The second from analysis of oxygen and total carbon content. The values calculated by the two methods are similar. The total and free carbon content was determined according to procedures described in PN-EN ISO 21068-2:2010P and additional free carbon content at temperatures higher than recommended by the standard. The sum of calculated values of SiO2 and SiC contents revealed measured excess of free carbon content.

To date there is no consensus about the most appropriate analytical method for measuring carbon nanotubes (CNTs), hampering the assessment and limiting the comparison of data. The goal of this study is to develop an approach for the assessment of the level and nature of inhalable multi-wall CNTs (MWCNTs) in an actual workplace setting by optimizing and evaluating existing analytical methods. In a company commercially producing MWCNTs, personal breathing zone samples were collected for the inhalable size fraction with IOM samplers; which were analyzed with carbon analysis, inductively coupled plasma mass spectrometry (ICP-MS) and scanning electron microscopy/ energy dispersive X-ray spectroscopy (SEM/EDX). Analytical methods were optimized for carbon analysis and SEM/EDX. More specifically, methods were applied and evaluated for background correction using carbon analyses and SEM/EDX, CNT structure count with SEM/EDX and subsequent mass conversion based on both carbon analyses and SEM/EDX. A moderate-to-high concordance correlation coefficient (RC) between carbon analyses and SEM/EDX was observed [RC = 0.81, 95% confidence interval (CI): 0.59-0.92] with an absolute mean difference of 59 μg m-3. A low RC between carbon analyses and ICP-MS (RC = 0.41, 95% CI: 0.07-0.67) with an absolute mean difference of 570 μg m-3 was observed. The large absolute difference between EC and metals is due to the presence of non-embedded inhalable catalyst particles, as a result of which MWCNT concentrations were over- estimated. Combining carbon analysis and SEM/EDX is the most suitable for quantitative exposure assessment of MWCNTs in an actual workplace situation. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

To date there is no consensus about the most appropriate analytical method for measuring carbon nanotubes (CNTs), hampering the assessment and limiting the comparison of data. The goal of this study is to develop an approach for the assessment of the level and nature of inhalable multi-wall CNTs (MWCNTs) in an actual workplace setting by optimizing and evaluating existing analytical methods. In a company commercially producing MWCNTs, personal breathing zone samples were collected for the inhalable size fraction with IOM samplers; which were analyzed with carbon analysis, inductively coupled plasma mass spectrometry (ICP-MS) and scanning electron microscopy/ energy dispersive X-ray spectroscopy (SEM/EDX). Analytical methods were optimized for carbon analysis and SEM/EDX. More specifically, methods were applied and evaluated for background correction using carbon analyses and SEM/EDX, CNT structure count with SEM/EDX and subsequent mass conversion based on both carbon analyses and SEM/EDX. A moderate-to-high concordance correlation coefficient (RC) between carbon analyses and SEM/EDX was observed [RC = 0.81, 95% confidence interval (CI): 0.59-0.92] with an absolute mean difference of 59 μg m-3. A low RC between carbon analyses and ICP-MS (RC = 0.41, 95% CI: 0.07-0.67) with an absolute mean difference of 570 μg m-3 was observed. The large absolute difference between EC and metals is due to the presence of non-embedded inhalable catalyst particles, as a result of which MWCNT concentrations were over- estimated. Combining carbon analysis and SEM/EDX is the most suitable for quantitative exposure assessment of MWCNTs in an actual workplace situation. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

Non-Rutherford elastic scattering is often used to obtain concentrations of low Z elements in heavier matrices that are normally difficult or not possible at all to analyze if the cross sections are of pure Rutherford type. Sometimes strong and narrow resonances with high cross section enhancement are used but they require multiple measurements per one sample and complicated data analysis. In the present work we applied the fact that the non-Rutherford elastic scattering cross section for 12C(alpha, alpha) 12C between 3.5 and 4 MeV is almost constant and several times larger than Rutherford at backward angles. This enhancement was sufficient to determine in only one measurement the amount and depth profile of carbon in different samples such as: thin SiC, a-Si1-xCx:H films and SiO2 samples implanted with 320 keV carbon ions. In case of SiO2 implanted samples the method was enough sensitive to determine differences in carbon depth profiles before and after the sample annealing. The sensitivity and depth profiling ability of the method was discussed and compared with some other IBA techniques that can be used for carbon determination such as 12C(p, p) 12C elastic scattering or 12C(d, p) 13C nuclear reaction.

The present paper focuses on the results obtained from the investigation on the soiling affecting surface monuments and relie fs of important Iranian archaeological sites. For this purpose, samples of surface deposit and damage layers were collected on immovable cultural relics located in the provinces of Khuzestan and Fars, in Southern Iran. Different analytical techniques were applied with the aim of characterising the mineralogical composition of the damage layers, investigating the embedded atmospheric particles, measuring the soluble salt concentration, identifying and quantifying the carbon components present. The results obtained will be presented, paying particular attention to the carbon fractions not linked to the carbonate substrate, but originated by biological agents and anthropogenic activities. The quantitave data of non carbonate carbon, comprising both elemental and organic fractions, obtained through the application of the methodology set up during the CARAMEL EC Project, as well as the organic composition of the soiling deposits (investigated by thermally assisted hydrolysis and methylation and gas chromatography-mass spectrometry) will be illustrated and discussed., The authors gratefully acknowledge the researches of the Research Center for Conservation of Cultural Relics (RCCCR) of Teheran for the support and collaboration during the sampling campaigns.