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As one of the three high-energy consumption sectors (industry, building, and transportation) in China, the transport sector faced a devastating resource and environment challenge. The transport sector was reportedly responsible for about 15.9% of the country’s total final energy consumption in 2008. This paper investigates the energy consumption and efficiency of China’s transport sector from 2003 to 2009. The transport energy data of 30 China administrative regions were divided into “three-belts” (Eastern, Western, and Central areas), and the corresponding turnovers were reported and analyzed using an index decomposition analysis (Logarithmic Mean Divisia Index). The energy data and turnover of the transport sector indicated that the high growth rate of turnover results is attributed to the high growth rate of diesel, assuming that diesel is the major fuel for freight transport. The growth of diesel is the main contributor to the overall growth of energy consumption. The growth rate of gasoline has become minimal since 2006. Since 2005, all three-belt areas, with regard to the effectiveness of energy conservation policies, have continuously improved their energy efficiencies based on the results of decomposition analysis. The energy intensity effect shows that the energy conservation and efficiency policies were more effective in the Central and Western areas than that in the Eastern area. On the other hand, the regional shift effect indicates that the policies favor to the Eastern area since only its regional shift effect contributes energy savings since 2008. The energy-mix effect is insignificant, which indicates that it is not necessary to conduct CO2 emission decomposition analysis due to the redundant observations. At last, the activity effect dominates the energy consumption increase (98.05% of the accumulated total energy increase) from 2003 to 2009, which is consistent with the rapid development of transportation in China. That is, the policies in the transport sector mainly focused on the economic development but the energy efficiencies in the study period.

Abstract In-situ CO2 biomethanisation offers a means to combine biogas upgrading with increased methane productivity, but its potential contribution to power-to-gas is often ignored due to concerns over process stability and control. The research presents an equation derived from fundamental chemical equilibria which predicts the relationship between partial CO2 pressure and digester pH, and allows estimation of the maximum achievable biogas methane content compatible with stable operation. A rapid experimental determination was also developed to support these predictions. The results were validated by long-term experiments using synthetic feedstock with different ammonia concentrations (2 and 3 g N L-1). Further trials carried out using food waste and sewage sludge as substrates showed stable operation at biogas methane contents of 92 and 90% CH4 and pH 8.5 and 7.9, respectively. CO2 biomethanisation was successfully demonstrated in a food waste digester with a total ammoniacal nitrogen of 4.8 g N L-1 with volumetric methane production enhanced by more than 2 times, from 2.29 to 5.01 L CH4 per L digester per day. The predictive approach used is applicable to digesters fed on different feedstocks and to hybrid systems with biomethanisation of both endogenous and exogenous CO2; and offers a basis for both process design guidelines and operational control. The output from the work thus provides engineers, operators and plant designers with a valuable tool for the successful implementation of in-situ biomethanisation in anaerobic digesters.

Abstract Biodiesel production was catalyzed by a novel magnetic carbonaceous acid (Zr-CMC-SO3H@3Fe-C400) with both Bronsted and Lewis sites synthesized by a four-step method: (i) metal (Fe) ion chelation, (ii) calcination, (iii) metal (Zr) ion chelation and embedding, and (iv) sulfonation. It catalyzed the esterification of oleic acid with 97% biodiesel yield, transesterification of high acid value (AV) soybean oil with 95% biodiesel yield, and pretreatment of Jatropha oil with AV reduced from 17.2 to 0.7 mg KOH/g. Biodiesel yields (>90%) at 90 °C for 4 h reaction time were obtained for ten cycles by easy magnetic separation which showed potential practical applications in the field of green production. The synthesized catalyst was characterized with elemental analysis, XRD, ICP-OES, FT-IR, BET, VSM, SEM-EDX, HRTEM, TG-DSC and Boehm titration.

Abstract A coalfield, in excess of 120×10 6 tonnes of coal in situ , has been discovered at Al-Kamil in south-eastern Oman. The coal is classified as highly-volatile bituminous type-A, with an average calorific value of 27.5 GJ per tonne. Unfortunately, it has on average ∼5% by weight sulphur content and an ash content of ∼14% by weight: so it is probably better suited for use as a fuel for electricity generation. However, such coal-fired generation, at present, would incur a higher cost than using indigenous natural gas, but would nevertheless provide an opportunity for diversification away from the existing over-dependence on natural gas and crude oil.

Abstract The deep decarbonisation of the power sector coupled with electrification of end-use sectors will be crucial towards a carbon neutral economy, as required to achieve the Paris Agreement's goal. Several studies have highlighted the relevance of electrification under deep decarbonisation. However, previous work does not explore what would be the major shifts towards electrification, i.e., in what economic activities it will likely occur and when up to 2050 considering gradually stricter GHG emissions constraints. This is of upmost relevance since relatively small variations in emission caps may trigger substantial modifications in specific components of the energy system, namely the shift for the electrification of a particular energy end-use, with impacts on the power sector’s portfolio. In this paper, we analyse the extension of the electrification of the energy system as a cost-effective strategy for deep decarbonisation. We set a large number of increasingly stringent mitigation caps to assess: (i) the degree of electrification of different energy end-uses across all economic activities, (ii) the impact in power sector portfolio and costs and (iii) investment needs. The novelty of this paper relies on the anticipation of electrification of activities traditionally supplied by non-electricity energy carriers, by exploring when and how such transformation may occur in the future, and how much it would cost. We assess the case of Portugal till 2050 by using the TIMES_PT model to generate 50 increasingly stricter decarbonisation scenarios. In the long term, incremental changes (+1%) in more aggressive decarbonisation targets (beyond −70% reduction) induce substantial increase in the share of electrification growth rates. Electric private vehicles, electricity-based steam and heat production in ceramic industrial sector and heat pumps in buildings are the most cost-effective electric technologies. We found that a decarbonisation up to near −80% of 1990′s levels of the Portuguese energy system does not have a significant impact on the power sector unit costs, and does not surpass historic values for some years. However, it should be noted that incremental changes (+1%) in more aggressive decarbonisation targets may increase sharply electricity costs in 2050 (+9%). Thus, focusing in only few scenarios may narrow the role of electrification (or other mitigation options) and its associated costs for deep decarbonisation. This paper allows researchers, planners and decision makers to enhance awareness regarding the relevance and cost-effectiveness of electrification under decarbonisation, namely its feasibility and affordability, providing fruitful insights.

Laboratory-created samples of methane hydrate (MH)-bearing media are a necessity because of the rarity and difficulty of obtaining naturally-occurring samples. The hypothesis that the inevitable heterogeneity in the phase saturations of the laboratory samples may lead to unreliable and non-repeatable results provided the impetus for this study, which aimed to determine the conditions under which maximum uniformity can be achieved. To that end, we designed four experiments involving different multi-stage cooling regimes (in terms of their duration and number of stages) to induce MH formation under excess-water conditions. In the absence of direct visualization capabilities, we analysed the experimental results by means of numerical simulation, which provided high-resolution predictions of the spatial distributions of the phase saturations in the cores and enabled the estimation of the parameters controlling the kinetic MH-formation behaviour through history-matching. Analysis of the numerical results indicated that, under the conditions of the experiments and with the design of the reactor, significant heterogeneities in phase saturation distributions were observed in all cases, leading to the conclusion that it is not possible to obtain cores with uniform phase saturation. Additionally, contrary to expectations, heterogeneities increased with the number of cooling stages and the duration of cooling, and this was attributed to imperfect insulation of the upper part of the reactor. A set of simulations involving perfect insulation of the reactor top confirmed the validity of this assumption: (a) predicting the formation of high-uniformity MH-bearing cores that became more homogeneous as the number of cooling stages and the length of the cooling period increased; and (b) providing important information for the improvement of the standard design of the experimental apparatus for the laboratory creation of MH-bearing cores using the excess water method.

Abstract Experimental results are presented on the role of benzene addition to H2S combustion at an equivalence ratio of three with respect to H2S (Claus condition) and complete combustion of benzene. The results are reported with 0.3%, 0.5% and 1% benzene addition to H2S/O2 flame. Combustion of H2S and benzene mixtures is of practical value for sulfur recovery during combustion of acid gases. The results showed that H2S combustion caused H2S to decompose to a minimum mole fraction with high conversion of H2S while the SO2 mole fraction reached a maximum value. Addition of benzene decreased the conversion of H2S with reduced mole fraction of SO2 in the reactor to subsequently reduce the formation of elemental sulfur. Benzene also caused significant production of H2, CO and COS formation along with faster decomposition of the formed SO2. Presence of benzene, even in trace amounts, in acid gas hinders sulfur conversion in a Claus reactor and increases emission of unwanted sulfur bearing compounds. Increased hydrogen production with benzene offers potential value for hydrogen recovery under certain conditions.

A preliminary design efficiency-optimization of an axial-flow compressor, using one-dimensional flow theory, is studied in this paper. A model for the optimum design of a compressor stage, assuming a fixed distribution of axial velocities, is presented. The absolute inlet and exit angles of the rotor are taken as design variables. Analytical relations between the isentropic efficiency and the flow coefficient, the work coefficient, the flow angles and the degree of reaction of the compressor stage are obtained. The results are universal and can be extended to the optimal design of a multi-stage compressor. Numerical examples are provided to illustrate the effects of various parameters on the optimal performance of the compressor stage.

Abstract This work combines experimental and computational fluid dynamics (CFD) results to derive global kinetics for biomass (pine wood) devolatilization during heating rates on the order of 10 5 K s - 1 , bulk flow peak temperatures between 1405 and 1667 K , and particle residence times below 0.1 s . Experiments were conducted on a laboratory laminar entrained flow reactor (LFR) using solid fuel feed rates on the order of 10–20 mg h - 1 . Employing a simple single step first order (SFOR) mechanism with an Arrhenius type rate expression, the best fit of the pyrolysis kinetics was found to be: A = 18.9 × 10 3 s - 1 , E a = 21 305 J mol - 1 . The accuracy of the derived global kinetics was supported by comparing predictions to experimental results from a 15 kW furnace. The work emphasizes the importance of characterizing the temperature history of the biomass particles when deriving pyrolysis kinetics. The present results indicate faster kinetics than found in the literature, leading to predicted residence times required for full conversion one order of magnitude lower than when compared to thermogravimetric analysis (TGA) derived kinetics.