Analysis of the emissions of volatile organic compounds from the compression ignition engine fueled by diesel–biodiesel blend and diesel oil using gas chromatography

This paper describes the procedures of the analysis of pollutant gases, as volatile organic compounds (benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene) emitted by engines, using high-resolution gas chromatography (HRGC). In a broad sense, CI engine burning diesel was compared with B10 and a drastic reduction was observed in the emissions of the aromatic compounds by using B10. Especially for benzene, the reduction of concentrations occurs on the level of about 19.5%. Although a concentration value below 1 μg ml⁻¹ has been obtained, this reduction is extremely significant since benzene is a carcinogenic compound.     

Combustion and emissions behaviour for ethanol–gasoline-blended fuels in a multipoint electronic fuel injection engine

The study investigated the combustion and emissions of a gasoline engine using ethanol–gasoline blends. The results indicated that the peak cylinder pressure of E10 is evidently lower, but that of E20 is identical to that of gasoline. At lower engine loads, the combustion velocity of gasoline is faster, and the peak heat release rate (HRR) is higher than that of the blends, but at higher engine loads, E20 shows faster combustion velocity and a little higher peak HRR. The brake thermal efficiency of the blends is almost similar to that of gasoline, but the brake-specific fuel consumption of the blends is slightly higher. With the increase in ethanol content in the blends, CO evidently decreases, HC slightly increases at high engine loads, and NOx depends on the engine operating conditions as well as the ethanol content. The acetaldehyde of the blends is evidently and the ethanol is slightly higher than that of gasoline.     

Combustion and emissions behaviour for methanol–gasoline blended fuels in a multipoint electronic fuel injection engine

The purpose of this study is to experimentally investigate the performance, combustion and pollutant emissions of a multipoint electronic fuel injection gasoline engine using methanol–gasoline blends. The results indicated that, with the increase in methanol (CH₃OH) content in the blends, the maximum engine torque and power are slightly decreased, the brake specific fuel consumption is evidently increased and brake thermal efficiency remains almost identical. At low engine loads and speeds, gasoline is observed to have faster combustion velocity, but the blends are faster at high engine loads and speeds. The carbon monoxide of the blends is slightly lower, hydrocarbon is slightly higher at high engine loads and nitrogen oxide is lower for M10 at low engine loads. The emissions of formaldehyde are evidently higher with the increase in CH₃OH content, but CH₃OH and acetaldehyde emissions of the blends show little variation.     

Optimisation of operating parameters on the performance characteristics of a free piston engine linear generator fuelled by CNG–H2 blends using the response surface methodology (RSM)

The free piston engine linear generator (FPELG) is a simple engine structure with few components, making it a promising power generation system. However, because the engine works without a crankshaft, the handling of the piston motion control (PMC) is the main challenge influencing the stability and performance of FPELGs. In this article, the optimal operating parameters of FPELG for maximising engine performance and reducing exhaust gas emissions were studied. Moreover, the influence of adding hydrogen (H₂) to compressed natural gas (CNG) fuel on FPELG performance was investigated. The influence of operating parameters on in-cylinder pressure was also analysed. The single-piston FPELG fuelled by CNG blended with H₂ was used to run the experiments. The response surface methodology (RSM), including the central composite design (CCD), was used. Then, adequacy models were developed and verified by ANOVA. Three independent factors on seven responses were utilised for optimisation. Results showed that the optimal operating conditions of lambda, ignition velocity, and injection position were 0.96, 0.53 m/s, and ?14.9 mm, respectively. The best-predicted values were as follows: indicated mean effective pressure (IMEP) of 7.6 bar, in-cylinder pressure of 27.87 bar, combustion efficiency of 39.64%, CO of 9531.41 ppm, CO₂ of 2.4%, HC of 551.75 ppm, and NO_X of 113.737 ppm. Furthermore, results showed that the experimental data could be fitted well with the predicted quadratic model.     

R&D intensity and carbon emissions in the G7: 1870–2014

We examine the effect of research and development (R&D) intensity on carbon dioxide (CO₂) emissions in the Group of Seven (G7) countries since the nineteenth century using a non-parametric panel data model. Our estimates suggest that the relationship between R&D and CO₂ emissions is time-varying. The estimated time-varying coefficient function of R&D was negative for three quarters of the period studied, but was positive for a 35-year period (1955–1990) during the second half of the twentieth century. Our non-parametric local linear estimates show that the common trend functions gradually increased for the first 110 years (1870–1980), but then flattened out and showed a slight decrease for the next three decades.     

Dazzled by diesel? The impact on carbon dioxide emissions of the shift to diesels in Europe through 2009

This paper identifies trends in new gasoline and diesel passenger car characteristics in the European Union between 1995 and 2009. By 2009 diesels had captured over 55% of the new vehicle market. While the diesel version of a given car model may have as much as 35% lower fuel use/km and 25% lower CO₂ emissions than its gasoline equivalent, diesel buyers have chosen increasingly large and more powerful cars than the gasoline market. As a result, new diesels bought in 2009 had only 2% lower average CO₂ emissions than new gasoline cars, a smaller advantage than in 1995. A Laspeyres decomposition investigates which factors were important contributors to the observed emission reductions and which factors offset savings in other areas. More than 95% of the reduction in CO₂ emissions per km from new vehicles arose because both diesel and gasoline new vehicle emissions/km fell, and only 5% arose because of the shift from gasoline to diesel technology. Increases in vehicle mass and power for both gasoline and diesel absorbed much of the technological efficiency improvements offered by both technologies. We also observe changes in the gasoline and diesel fleets in eight EU countries and find changes in fuel and emissions intensities consistent with the changes in new vehicles reported. While diesel cars continue to be driven far farther than gasoline cars, we attribute only some of this difference to a “rebound effect”. We conclude that while diesel technology has permitted significant fuel savings, the switch from gasoline to diesel in the new vehicle market contributed little itself to the observed reductions in CO₂ emissions from new vehicles.     

Investigation on the effect of injection system parameters on performance and emission characteristics of a twin cylinder compression ignition direct injection engine fuelled with pongamia biodiesel–diesel blend using response surface methodology

This study is aimed at investigating the effect of injection system parameters such as injection pressure, injection timing and nozzle tip protrusion on the performance and emission characteristics of a twin cylinder water cooled naturally aspirated CIDI engine. Biodiesel, derived from pongamia seeds through transesterification process, blended with diesel was used as fuel in this work. The experiments were designed using a statistical tool known as Design of Experiments (DoE) based on response surface methodology (RSM). The resultant models of the response surface methodology were helpful to predict the response parameters such as Brake Specific Energy Consumption (BSEC), Brake Thermal Efficiency (BTE), Carbon monoxide (CO), Hydrocarbon (HC), smoke opacity and Nitrogen Oxides (NO_x) and further to identify the significant interactions between the input factors on the responses. The results depicted that the BSEC, CO, HC and smoke opacity were lesser, and BTE and NO_x were higher at 2.5 mm nozzle tip protrusion, 225 bar of injection pressure and at 30° BTDC of injection timing. Optimization of injection system parameters was performed using the desirability approach of the response surface methodology for better performance and lower NO_x emission. An injection pressure of 225 bar, injection timing of 21° BTDC and 2.5 mm nozzle tip protrusion were found to be optimal values for the pongamia biodiesel blended diesel fuel operation in the test engine of 7.5 kW at 1500 rpm.     

Glassy carbon electrode modified by Pd–Cu bimetallic nano-dendrites film decorated on the reduced graphene oxide using galvanic replacement as a low-cost anode in methanol fuel cells

Glassy carbon electrode (GCE) modified by reduced graphene oxide Cu–Pd nano-dendrimer (Pd-CuNDs-RGO/GCE) was prepared using electro-deposition and spontaneous displacement methods. Graphene oxide was put on the surface of GCE by drop-casting, then a thin film of reduced graphene oxide (RGO) was formed by electro-reduction at ?0.9 V. The copper nano-dendrimers (CuNDs) were electro-plated on RGO/GCE surface. Finally, Pd-CuNDs-RGO/GCE was prepared by the spontaneous replacement of CuNDs with palladium nanoparticles (PdNPs) in a dilute solution of palladium. The electrode surface was characterized using field-emission scanning electron microscopy (FESEM), X-ray energy diffraction (EDX) spectroscopy, and electrochemical techniques. The electrochemical behavior of the modified electrode in the oxidation of alkaline solution of methanol was investigated. The experimental conditions affecting the performance of the modified electrode in the methanol oxidation were studied and optimized. Finally, the proposed electrode has the onset potential of ?0.5 V and the ratio of i_f/i_b equal to 2.2, which confirms the high catalytic activity. The electrode has appropriate stability and shows about 86% of initial activity after 100 times testing.     

Enhancing the durability of multi-walled carbon nanotube supported by Pt and Pt–Pd nanoparticles in gas diffusion electrodes

This work tries to improve the durability of electrocatalysts of gas diffusion electrodes (GDEs) by using multi-walled carbon nanotube supported Pt–Pd bimetallic (Pt–Pd/MWCNT). The durability investigation of multi-walled carbon nanotube supported metals was evaluated by a repetitive potential cycling (RPC) corrosion test and by extended constant potential (ECP) experiments. Potential cycling tests were performed from −0.3 to 1.2 V at 50 mV s⁻¹ in 1 mol L⁻¹ H₂SO₄. Extended constant potential (ECP) durability test were also carried out on the GDEs by 30 h of constant potential operation at 0.8 V vs. Ag/AgCl. The smaller performance loss was observed on the GDE using Pt–Pd/MWCNT as electrocatalyst compared with GDE using Pt/MWCNT during both durability tests. ICP analysis also suggests that the dissolution of Pt nanoparticles from the carbon nanotube surface is hindered when Pd is present.     

Effects of a carbon price in the U.S. on economic sectors,resource use,and emissions: An input–output approach

Despite differences in their implementation, most carbon policies aim to have similar outcomes: effectively raising the price of carbon-intensive products relative to non-carbon-intensive products. While it is possible to predict the simple broad-scale economic impacts of raising the price of carbon-intensive products—the demand for non-carbon-intensive products will increase—understanding the economic and environmental impacts of carbon policies throughout the life cycle of both types of products is more difficult. Using the example of a carbon tax, this study proposes a methodology that integrates short-term policy-induced consumer demand changes into the input–output framework to analyze the environmental and economic repercussions of a policy. Environmental repercussions include the direct and the indirect impacts on emissions, materials flow in the economy, and the reliance on various ecosystem goods and services. The approach combines economic data with data about physical flow of fossil fuels between sectors, consumption of natural resources and emissions from each sector. It applies several input–output modeling equations sequentially and uses various levels of aggregation/disaggregation. It is illustrated with the data for the 2002 U.S. economy and physical flows. The framework provides insight into the short-term complex interactions between carbon price and its economic and environmental effects.     

Morphological influence of graphitic carbon nanofibers by N–F dual-doping on Pt electrocatalytic activity and stability for oxygen reduction reaction in polymer electrolyte membrane fuel cells

Morphology of carbon nanofibers significantly effects Pt nanoparticles dispersion and specific interaction with the support, which is an important aspect in the fuel cell performance of the electrocatalysts. This study emphasizes, the defects creation and structural evolution comprised due to N–F co-doping on graphitic carbon nanofibers (GNFs) of different morphologies, viz. GNF-linearly aligned platelets (L), antlers (A), herringbone (H), and their specific interaction with Pt nanoparticle in enhancing the oxygen reduction reaction (ORR). GNFs–NF–Pt catalysts exhibit better ORR electrocatalytic activity, superior durability that is solely ascribed to the morphological evolution and the doped N–F heteroatoms, prompting the charge density variations in the resultant carbon fiber matrices. Amongst, H–NF–Pt catalyst performed outstanding ORR activity with exceptional electrochemical stability, which shows only 20 mV loss in the half-wave potential whilst 100 mV loss for Pt/C catalyst on 20,000 potential cycling. The PEMFC comprising H–NF–Pt as cathode catalyst with minimum loading of 0.10 mg cm^?2, delivers power density of 0.942 W cm^?2 at current density of 2.50 A cm^?2 without backpressures in H₂–O₂ feeds. The H–NF–Pt catalyst owing to its hierarchical architectures, performs well in PEMFC at the minimized catalyst loading with outstanding stability that can significantly decrease total price for the fuel cell.     

Co-production of hydrogen and carbon nanomaterials using NiCu/SBA15 catalysts by pyrolysis of a wax by-product: Effect of Ni–Cu loading on the catalytic activity

The simultaneous production of H₂ and carbon nanomaterials (CNMs) over NiCu/SBA15 catalysts with different Ni–Cu contents (10, 20, 30, 40 and 50 wt%) was investigated using the pyrolysis-catalysis process of paraffin wax. The fresh and spent catalysts were characterized by various techniques including H₂-TPR, XRD, TEM, Raman spectroscopy and BET surface area. TEM observations showed that broad particle size distributions were formed in fresh 40NiCu/SBA15 and 50NiCu/SBA15 catalysts, while catalysts with smaller Ni–Cu contents displayed better metals dispersion. We found that the catalyst activity is related to the type of carbon nanomaterials, catalyst particle size, and catalyst loading with Ni–Cu. Also, the largest yield of H₂ and CNMs was achieved using the 30NiCu/SBA15 catalyst. NiCu/SBA15 catalysts with Ni-Cu contents of 30–50 wt% exhibited good catalytic stability and similar activity in terms of H₂ yield, especially at reaction time above 225 min. Small diameters carbon nanofibers (CNFs) were produced over the 10NiCu/SBA15 catalyst, while a mixture of CNFs and carbon nano-onions (CNOs) was produced using catalysts with Ni-Cu loadings of 20–50 wt%. The generation of octopus-like CNFs over large catalyst particles was associated with the observed catalytic stability of H₂ production. Raman spectroscopy and XRD analyses demonstrated the formation of the best quality CNMs using the 20NiCu/SBA15 catalyst.     

Comments on “Reduction in carbon dioxide and production of methane by biological reaction in the electronics industry” by Kim et al., International Journal of Hydrogen Energy 2013;38:3488–3496

In the comments, energy consumption for H₂ production and CO₂ fixation are balanced to evaluate the validity of a ‘novel’ electrocoagulation defluoridation process, which was addressed to have a potential to simultaneously reduce CO₂ emission and generate energy (CH₄). After the balance calculation, it becomes clear that the proposed process seems unreasonable in energy balance. On the contrary, the process is an energy-intensive system, associated with a net CO₂ emission.     

Enhancing sustainable bioelectricity generation using facile synthesis of nanostructures of bimetallic Co–Ni at the combined support of halloysite nanotubes and reduced graphene oxide as novel oxygen reduction reaction electrocatalyst in single-chambered microbial fuel cells

The present study aims to utilize the high surface area of the nanotube structure of halloysite (HNTs), an aluminosilicate clay, and conductivity of reduced graphene oxide (rGO) as support material for the deposition of nickel (Ni) and cobalt (Co) nanoparticles. With that aim, a novel bimetallic cathode electrocatalyst, Co–Ni @ HNTs-rGO (Catalyst H₃), is developed. This catalyst is characterized by X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Transmission Electron Microscopy (TEM). Catalyst H₃ demonstrates outstanding oxygen reduction reaction (ORR) activity, electrochemical stability, electrocatalytic performance, and lowest resistance in comparison to the other developed catalysts and conventional Pt/C. Catalyst H₃ is used in single-chambered MFCs (microbial fuel cells), where the anode is filled with molasses-laden wastewater. The attained maximum power density in MFC (catalyst H₃) is 455 ± 9 mW/m², which is higher than other catalysts. All the results indicate towards its potential use in MFC application.     

Hydrogen production by the Cu–Cl thermochemical cycle: Investigation of the key step of hydrolysing CuCl2 to Cu2OCl2 and HCl using a spray reactor

One of the most challenging steps in the thermochemical Cu–Cl cycle for the production of hydrogen is the hydrolysis of CuCl₂ into Cu₂OCl₂ and HCl while avoiding the need for excess water and the undesired thermolysis reaction, which gives CuCl and Cl₂. Argonne National Laboratory has designed a spray reactor where an aqueous solution of CuCl₂ is atomized into a heated zone, into which steam/Ar are injected in co- or counter-current flow. The solid products of the reaction were analyzed by XRD and SEM. With a pneumatic nebulizer, the counter-current flow design gave high yields of Cu₂OCl₂ compared to the co-current flow design, but some CuCl₂ remained unreacted in both designs. With an ultrasonic nozzle, essentially 100% yields of Cu₂OCl₂ were obtained. Some CuCl was present in the products with both types of atomizers but this is believed to be due to decomposition of Cu₂OCl₂ rather than CuCl₂. Analyses of gaseous products from the hydrolysis reactions in a fixed bed were conducted at the Commissariat à L'Energie Atomique using ultraviolet-visible spectrometry and conductivity. At a reaction temperature of 390 °C, the desired HCl was formed while no Cl₂ was detected until the bed temperature was above 400 °C.