共查询到20条相似文献,搜索用时 15 毫秒
1.
By using the latest China–Japan input–output data sets and the index decomposition analysis (IDA) approach, this article analyzes the driving forces of CO2 emissions embodied in trade between the two countries during 1990–2000. We found that the growth of trade volume had a large influence on the increase of CO2 emissions embodiments in bilateral trade. The dramatic decline in carbon intensity of the Chinese economy is a primary cause in offsetting CO2 emissions exported from China to Japan over 1995–2000. We argue that a better understanding of the factors affecting CO2 emissions embodied in international trade will assist in seeking more effective climate policies with wider participation in the post-Kyoto regime. 相似文献
2.
This paper examines CO2 emissions embodied in Japan–China trade. Besides directly quantifying the flow of CO2 emissions between the two countries by using a traditional input–output (IO) model, this study also estimates the effect of bilateral trade to CO2 emissions by scenario analysis. The time series of quantifications indicate that CO2 emissions embodied in exported goods from Japan to China increased overall from 1990 to 2000. The exported CO2 emissions from China to Japan greatly increased in the first half of the 1990s. However, by 2000, the amount of emissions had reduced from 1995 levels. Regardless, there was a net export of CO2 emissions from China to Japan during 1990–2000. The scenario comparison shows that the bilateral trade has helped the reduction of CO2 emissions. On average, the Chinese economy was confirmed to be much more carbon-intensive than Japan. The regression analysis shows a significant but not perfect correlation between the carbon intensities at the sector level of the two countries. In terms of CO2 emission reduction opportunities, most sectors of Chinese industry could benefit from learning Japanese technologies that produce lower carbon intensities. 相似文献
3.
The effect of national energy policies on a local Swedish district heating (DH) system has been studied, regarding the profitability of new investments and the potential for climate change mitigation. The DH system has been optimised regarding three investments: biomass-fuelled CHP (bio CHP), natural gas-fuelled combined cycle CHP (NGCC CHP) and biomass-fuelled heat-only boiler (bio HOB) in two scenarios (with or without national taxes and policy instruments). In both scenarios EU’s tradable CO2 emission permits are included. Results from the study show that when national policies are included, the most cost-effective investment option is the bio CHP technology. However, when national taxes and policy instruments are excluded, the DH system containing the NGCC CHP plant has 30% lower system cost than the bio CHP system. Regardless of the scenario and when coal condensing is considered as marginal electricity production, the NGCC CHP has the largest global CO2 reduction potential, about 300 ktonne CO2. However, the CO2 reduction potential is highly dependent on the marginal electricity production. Demonstrated here is that national policies such as tradable green certificates can, when applied to DH systems, contribute to investments that will not fully utilise the DH systems’ potential for global CO2 emissions reductions. 相似文献
4.
To gain insight into changes in CO2 emissions embodied in China–US trade, an input–output analysis based on the emergy/dollar ratio (EDR) is used to estimate embodied CO2 emissions; a structural decomposition analysis (SDA) is employed to analyze the driving factors for changes in CO2 emissions embodied in China's exports to the US during 2002–2007. The results of the input–output analysis show that net export of CO2 emissions increased quickly from 2002 to 2005 but decreased from 2005 to 2007. These trends are due to a reduction in total CO2 emission intensity, a decrease in the exchange rate, and small imports of embodied CO2 emissions. The results of the SDA demonstrate that total export volume was the largest driving factor for the increase in embodied CO2 emissions during 2002–2007, followed by intermediate input structure. Direct CO2 emissions intensity had a negative effect on changes in embodied CO2 emissions. The results suggest that China should establish a framework for allocating emission responsibilities, enhance energy efficiency, and improve intermediate input structure. 相似文献
5.
With the intensification of global warming and continued growth in energy consumption, China is facing increasing pressure to cut its CO2 (carbon dioxide) emissions down. This paper discusses the driving forces influencing China's CO2 emissions based on Path–STIRPAT model—a method combining Path analysis with STIRPAT (stochastic impacts by regression on population, affluence and technology) model. The analysis shows that GDP per capita (A), industrial structure (IS), population (P), urbanization level (R) and technology level (T) are the main factors influencing China's CO2 emissions, which exert an influence interactively and collaboratively. The sequence of the size of factors' direct influence on China's CO2 emission is A>T>P>R>IS, while that of factors' total influence is A>R>P>T>IS. One percent increase in A, IS, P, R and T leads to 0.44, 1.58, 1.31, 1.12 and −1.09 percentage change in CO2 emission totally, where their direct contribution is 0.45, 0.07, 0.63, 0.08, 0.92, respectively. Improving T is the most important way for CO2 reduction in China. 相似文献
6.
This study asks whether sub-national inequalities in carbon dioxide (CO2) emissions mirror international patterns in carbon inequality using the case study of China. Several studies have examined global-level carbon inequality; however, such approaches have not been used on a sub-national scale. This study examines inter-provincial inequality in CO2 emissions within China using common measures of inequality (coefficient of variation, Gini Index, Theil Index) to analyze provincial-level data derived from the IPCC reference approach for the years 1997–2007. It decomposes CO2 emissions inequality into its inter-regional and intra-regional components. Patterns of per capita CO2 emissions inequality in China appear superficially similar to, though slightly lower than, per capita income inequality. However, decomposing these inequalities reveals different patterns. While inter-provincial income inequality is highly regional in character, inter-provincial CO2 emissions inequality is primarily intra-regional. While apparently similar, global patterns in CO2 emissions are not mirrored at the sub-national scale. 相似文献
7.
The depletion of non-renewable resources and the environmental impact of energy consumption, particularly energy use in buildings, have awakened considerable interest in energy efficiency. Building energy codes have recently become effective techniques to achieve efficiency targets. The Electricity and Water Authority in Bahrain has set a target of 40% reduction of building electricity consumption and CO2 emissions to be achieved by using envelope thermal insulation codes. This paper investigates the ability of the current codes to achieve such a benchmark and evaluates their impact on building energy consumption. The results of a simulation study are employed to investigate the impact of the Bahraini codes on the energy and environmental performance of buildings. The study focuses on air-conditioned commercial buildings and concludes that envelope codes, at best, are likely to reduce the energy use of the commercial sector by 25% if the building envelope is well-insulated and efficient glazing is used. Bahraini net CO2 emissions could drop to around 7.1%. The simulation results show that the current energy codes alone are not sufficient to achieve a 40% reduction benchmark, and therefore, more effort should be spent on moving towards a more comprehensive approach. 相似文献
8.
Salvatore Abate Chiara GenoveseSiglinda Perathoner Gabriele Centi 《International Journal of Hydrogen Energy》2010
The effect of CO and CO2 on the performance and stability of Pd–Ag thin film membranes prepared by electroless plating deposition (EPD) was investigated, observing the presence of dissociation to carbon and oxygen which slowly diffuse in the membrane influencing also H2 permeability. The effect of the two carbon oxides was investigated both separately and combined in the 400–450 °C temperature range over long-term cumulative experiments (up to over 350 h) on a membrane that already worked for over 350 h in H2 or H2–N2 mixtures. An increase of the H2 permeation flux was observed feeding only CO2 in the range 10–20%. This effect was interpreted as deriving from the facilitated H2 flux caused from oxygen diffusion (deriving from CO2 dissociation) in the membrane. CO induces instead a partial inhibition on the H2 flux deriving from the negative effect of CO competitive chemisorption as well as C diffusion in the membrane, which overcome the positive effect associated to oxygen diffusion in the membrane. Carbon and oxygen diffuse through the membrane with a rate two order of magnitude lower than hydrogen, and recombinate at the permeate side forming CO, CO2 and CH4 which amount increases with time-on-stream. The effect is reversible and not associated with the creation of cracks or defects in the membrane, as supported by leak tests. 相似文献
9.
Santosh K. Paidi Amrutha Bhavaraju Mohammad Akram Sudarshan Kumar 《International Journal of Hydrogen Energy》2013
The laminar burning velocities of H2–air mixtures diluted with N2 or CO2 gas at high temperatures were obtained from planar flames observed in externally heated diverging channels. Experiments were conducted for an equivalence ratio range of 0.8–1.3 and temperature range of 350–600 K with various dilution rates. In addition, computational predictions for burning velocities and their comparison with experimental results and detailed flame structures have been presented. Sensitivity analysis was carried out to identify important reactions and their contribution to the laminar burning velocity. The computational predictions are in reasonably good agreement with the present experimental data (especially for N2 dilution case). The burning velocity maxima was observed for slightly rich mixtures and this maxima was found to shift to higher equivalence ratios (Ф) with a decrease in the dilution. The effect of CO2 dilution was more profound than N2 dilution in reducing the burning velocity of mixtures at higher temperatures. 相似文献
10.
This study has been implemented in two sections. At first, the turbulent jet flame of DLR-B is simulated by combining the k–ε turbulence model and a steady flamelet approach. The DLR-B flame under consideration has been experimentally investigated by Meier et al. who obtained velocity and scalar statistics. The fuel jet composition is 33.2% H2, 22.1% CH4 and 44.7% N2 by volume. The jet exit velocity is 63.2 m/s resulting in a Reynolds number of 22,800. Our focus in the first part is to validate the developed numerical code. Comparison with experiments showed good agreement for temperature and species distribution. At the second part, we exchanged methane with propane in the fuel composition whilst maintaining all other operating conditions unchanged. We investigated the effect of hydrogen concentration on C3H8–H2–N2 mixtures so that propane mole fraction extent is fixed. The hydrogen volume concentration rose from 33.2% up to 73.2%. The achieved consequences revealed that hydrogen addition produces elongated flame with increased levels of radiative heat flux and CO pollutant emission. The latter behavior might be due to quenching of CO oxidation process in the light of excessive cold air downstream of reaction zone. 相似文献
11.
12.
Ignition delay times of H2/O2 mixtures highly diluted with Ar and doped with various amounts of N2O (100, 400, 1600, 3200 ppm) were measured in a shock tube behind reflected shock waves over a wide range of temperatures (940–1675 K). The pressure range investigated during this work (around 1.6, 13 and 32 atm) allows studying the effect of N2O on hydrogen ignition at pressure conditions that have never been heretofore investigated. Ignition delay times were decreased when N2O was added to the mixture only for the higher nitrous oxide concentrations, and some changes in the activation energy were also observed at 1.5 and 32 atm. When it occurred, the decrease in the ignition delay time was proportional to the amount of N2O added and depended on pressure and temperature conditions. A detailed chemical kinetics model was developed using kinetic mechanisms from the literature. This model predicts well the experimental data obtained during this study and from the literature. The chemical analysis using this model showed that the decrease in the ignition delay time was mainly due to the reaction N2O + M ? N2 + O + M which provides O atoms to strengthen the channel O + H2 ? OH + H. 相似文献
13.
Jiasheng Wang Shumin Han Wei Zhang Dan Liang Yuan Li Xin Zhao Ruibing Wang 《International Journal of Hydrogen Energy》2013
A 2LiBH4–MgH2–MoS2 composite was prepared by solid-state ball milling, and the effects of MoS2 as an additive on the hydrogen storage properties of 2LiBH4–MgH2 system together with the corresponding mechanism were investigated. As shown in the TG–DSC and MS results, with the addition of 20 wt.% of MoS2, the onset dehydrogenation temperature is reduced to 206 °C, which is 113 °C lower than that of the pristine 2LiBH4–MgH2 system. Meanwhile, the total dehydrogenation amount can be increased from 9.26 wt.% to 10.47 wt.%, and no gas impurities such as B2H6 and H2S are released. Furthermore, MoS2 improves the dehydrogenation kinetics, and lowers the activation energy (Ea) 34.49 kJ mol−1 of the dehydrogenation reaction between Mg and LiBH4 to a value lower than that of the pristine 2LiBH4–MgH2 sample. According to the XRD test, Li2S and MoB2 are formed by the reaction between LiBH4 and MoS2, which act as catalysts and are responsible for the improved hydrogen storage properties of the 2LiBH4–MgH2 system. 相似文献
14.
The permeance of a 50 μm thick PdAg (25 wt.% of silver) tubular membrane towards hydrogen was evaluated for hydrogen feed streams or binary mixtures of industrial relevance, namely of H2/CO or H2/CO2. 相似文献
15.
Al2O3–2SiO2 amorphous powders are synthesized by sol–gel method with tetraethoxysilane (TEOS) and aluminum nitrate (ANN) as the starting materials. The microstructure and phase structure of the powders are investigated by SEM and XRD analysis. Geopolymer materials samples are prepared by mechanically mixing stoichiometric amounts of calcined Al2O3–2SiO2 powders and sodium silicate solutions to allow a mass ratio of Na2O/Al2O3 = 0.4, 0.375, 0.35, 0.325, 0.288, 0.26, 0.23 or 0.2 separately, and finally to form a homogenous slurry at a fixed H2O/Na2O mole ratio = 11.7. The results show that the synthetic Al2O3–2SiO2 powders have polycondensed property and their compressive strengthes are similar to that of nature metakaolin geopolymer materials. The results also show that the water consumption is not the main influencing factor on electrical conductivity of harden geopolymer materials but it can intensively affect the microstructure of geopolymer materials. In addition, the electrical conductivity of harden geopolymer sample is investigated, and the results show that the geopolymer materials have a high ionic electrical conductivity of about 1.5 × 10−6 S cm−1 in air at room temperature. 相似文献
16.
V. Ratna Kishore Ringkhang MuchaharyAnjan Ray M.R. Ravi 《International Journal of Hydrogen Energy》2009
Global warming due to CO2 emissions has led to the projection of hydrogen as an important fuel for future. A lot of research has been going on to design combustion appliances for hydrogen as fuel. This has necessitated fundamental research on combustion characteristics of hydrogen fuel. In this work, a combination of experiments and computational simulations was employed to study the effects of diluents (CO2, N2, and Ar) on the laminar burning velocity of premixed hydrogen/oxygen flames using the heat flux method. The experiments were conducted to measure laminar burning velocity for a range of equivalence ratios at atmospheric pressure and temperature (300 K) with reactant mixtures containing varying concentrations of CO2, N2, and Ar as diluents. Measured burning velocities were compared with computed results obtained from one-dimensional laminar premixed flame code PREMIX with detailed chemical kinetics and good agreement was obtained. The effectiveness of diluents in reduction of laminar burning velocity for a given diluent concentration is in the increasing order of argon, nitrogen, carbon dioxide. This may be due to increased capabilities either to quench the reaction zone by increased specific heat or due to reduced transport rates. The lean and stoichiometric H2/O2/CO2 flames with 65% CO2 dilution exhibited cellular flame structures. Detailed three-dimensional simulation was performed to understand lean H2/O2/CO2 cellular flame structure and cell count from computed flame matched well with the experimental cellular flame. 相似文献
17.
18.
Michael U. Niemann Sesha S. Srinivasan Ashok Kumar Elias K. Stefanakos D. Yogi Goswami Kimberly McGrath 《International Journal of Hydrogen Energy》2009
In this article, we investigate the ternary LiNH2–MgH2–LiBH4 hydrogen storage system by adopting various processing reaction pathways. The stoichiometric ratio of LiNH2:MgH2:LiBH4 is kept constant with a 2:1:1 molar ratio. All samples are prepared using solid-state mechano-chemical synthesis with a constant rotational speed, but with varying milling duration. Furthermore, the order of addition of parent compounds as well as the crystallite size of MgH2 are varied before milling. All samples are intimate mixtures of Li–B–N–H quaternary hydride phase with MgH2, as evidenced by XRD and FTIR measurements. It is found that the samples with MgH2 crystallite sizes of approximately 10 nm exhibit lower initial hydrogen release at a temperature of 150 °C. Furthermore, it is observed that the crystallite size of Li–B–N–H has a significant effect on the amount of hydrogen release with an optimum size of 28 nm. The as-synthesized hydrides exhibit two main hydrogen release temperatures, one around 160 °C and the other around 300 °C. The main hydrogen release temperature is reduced from 310 °C to 270 °C, while hydrogen is first reversibly released at temperatures as low as 150 °C with a total hydrogen capacity of ∼6 wt.%. Detailed thermal, capacity, structural and microstructural properties are discussed and correlated with the activation energies of these materials. 相似文献
19.
Proper solution of vapor liquid equilibrium (VLE) is essential to the design and operation of CO2 capture and storage system (CCS). According to the requirements of engineering applications, cubic equations of state (EOS) are preferable to predict VLE properties. This paper evaluates the reliabilities of five cubic EOSs, including PR, PT, RK, SRK and 3P1T for predicting VLE of CO2 and binary CO2-mixtures containing CH4, H2S, SO2, Ar, N2 or O2, based on the comparisons with the collected experimental data. Results show that SRK is superior in the calculations about the saturated pressure of pure CO2; while for the VLE properties of binary CO2-mixtures, PR, PT and SRK are generally superior to RK and 3P1T. The impacts of binary interaction parameter kij were also analyzed. kij has very clear effects on the calculating accuracy of an EOS in the property calculations of CO2-mixtures. In order to improve the calculation accuracy, the binary interaction parameter was calibrated for all of the studied EOSs regarding every binary CO2-mixture. 相似文献
20.
The aim of the article was to compare the pre- and post-combustion CO2 capture process employing the chemical absorption technology. The integration of the chemical absorption process before or after the coal combustion has an impact on the power plant efficiency because, in both cases, the thermal energy consumption for solvent regeneration is provided by the steam extracted from the low pressure steam turbine. The solvent used in this study for the CO2 capture was monoethanolamine (MEA) with a weight concentration of 30%. In the case of the pre-combustion integration, the coal gasification was analysed for different ratios air/fuel (A/F) in order to determine its influences on the syngas composition and consequently on the low heating value (LHV). The LHV maximum value (28 MJ/kg) was obtained for an A/F ratio of 0.5 kgair/kgfuel, for which the carbon dioxide concentration in the syngas was the highest (17.26%). But, considering the carbon dioxide capture, the useful energy (the difference between the thermal energy available with the syngas fuel and the thermal energy required for solvent regeneration) was minimal. The maximum value (61.59 MJ) for the useful energy was obtained for an A/F ratio of 4 kgair/kgfuel. Also, in both cases, the chemical absorption pre- and post-combustion process, the power plant efficiency decreases with the growth of the L/G ratio. In the case of the pre-combustion process, considering the CO2 capture efficiency of 90%, the L/G ratio obtained was of 2.55 molsolvent/molsyngas and the heat required for the solvent regeneration was of 2.18 GJ/tCO2. In the case of the post-combustion CO2 capture, for the same value of the CO2 capture efficiency, the L/G ratio obtained was of 1.13 molsolvent/molflue gas and the heat required was of 2.80 GJ/tCO2. However, the integration of the CO2 capture process in the power plant leads to reducing the global efficiency to 30% in the pre-combustion case and to 38% to the post-combustion case. 相似文献