•Deployment of renewables is essential for sustainable development.•Top 38 countries are selected using the Renewable Energy Country Attractive Index.•Long-run output elasticities estimated for each ...country.•Analysis for both panel and individual countries.•The message varies for future renewable deployment into the growth process.
This research aims to investigate the effects of renewable energy consumption on the economic growth of major renewable energy consuming countries in the world. Using the Renewable Energy Country Attractiveness Index developed by the Ernst & Young Global Limited, we choose 38 top renewable energy consuming countries to explain the growth process between 1991 and 2012. With panel estimation techniques, our findings establish cross-sectional dependence and heterogeneity across the countries. We confirm the evidence of long-run dynamics between economic growth, and traditional and energy-related inputs. Findings from long-run output elasticities indicate that renewable energy consumption has a significant positive impact on the economic output for 57% of our selected countries. For robustness, we also carried out time-series analyses of long-run output elasticities. Our findings suggest that governments, energy planners, international cooperation agencies and associated bodies must act together in increasing renewable energy investment for low carbon growth in most of these economies.
A transversely isotropic elastic medium with a vertical axis of symmetry is considered. We obtain dispersion equations in real terms for guided Love and Rayleigh waves in a such a medium consisting ...of horizontal layers sandwiched between two half‐spaces by brief modifications of the available literatures on dispersion equations in elastic layered media through transfer matrix. To illustrate the applicability, dispersion curves of guided waves are computed for three‐ and five‐layered symmetric models with transversely isotropic coal seam in the middle. The Airy phase is marked by a minimum or maximum of group velocity in a dispersion curve, and this phase is important to get seam structure for mining safety. For the first three modes, the effect of Thomsen anisotropy parameters γ, ε and δ of a coal seam on frequency (fA) and group velocity (UA) of the Airy phase is similar in three‐ and five‐layered models. For guided Love waves, fA and UA have nearly a uniform increase with the increase of γ. For guided Rayleigh waves, the increase of ε causes fA and UA to increase; however, the increase of δ causes fA and UA to decrease.
Abstract
Lignocellulosic biomass is an attractive renewable resource to produce biofuel or platform chemicals. Efficient and cost-effective conversion systems of lignocellulosic biomass depend on ...their appropriate pretreatment processes. Alkali or dilute acid pretreatment of biomass requires a high temperature (> 150 °C) to remove xylan (hemicellulosic sugar) and lignin partially. In this study, peracetic acid was used to pretreat biomass feedstocks, including hardwood and softwood species. It was found that the thermally-assisted dilute acid pretreatment of biomass conducted under the mild temperature of 90 °C up to 5 h resulted in the effective removal of lignin from the biomass with a negligible loss of carbohydrates. This thermally-assisted pretreatment achieved 90% of delignification, and this result was compared with the microwave-assisted pretreatment method. In addition, the crystallinity index (
CrI
), surface morphology, and chemical structure were significantly changed after the acid pretreatment. The biomass digestibility increased significantly with increased reaction time, by 32% and 23% for hardwood and softwood, respectively. From this study, it is clear that peracetic acid pretreatment is an effective method to enrich glucan content in biomass by delignification.
Direct C-O hydrogenolysis of bioglycerine to produce 1,3-propanediol selectively is a vital technology that can expand the scope of biodiesel industry and green chemical production from biomass. ...Herein we report sulphuric acid-activated montmorillonite clay supported platinum nanoparticles as highly effective solid acid catalysts for the selective production of 1,3-propanediol from glycerol. The catalytic performances of the catalysts were investigated in the hydrogenolysis of glycerol with a fixed bed reactor under ambient pressure. The results were found promising and showed that the activation of montmorillonite by sulphuric acid incorporated Brønsted acidity in the catalyst and significantly improved the selectivity to 1,3-propanediol. The catalytic performance of different platinum loaded catalysts was examined and 2 wt% Pt/S-MMT catalyst presented superior activity among others validating 62% 1,3-propanediol selectivity at 94% glycerol conversion. The catalytic activity of 2Pt/S-MMT was systematically investigated under varying reaction parameters including reaction temperature, hydrogen flow rate, glycerol concentration, weight hourly space velocity, and contact time to derive the optimum conditions for the reaction. The catalyst stability, reusability and structure-activity correlation were also elucidated. The high performance of the catalyst could be ascribed to well disperse Pt nanoparticles immobilized on acid-activated montmorillonite, wider pore-structure and appropriate acid sites of the catalyst.
This study assessed the entrained flow co-gasification characteristics of coal and biomass using thermodynamic equilibrium modelling. The model was validated against entrained flow gasifier data ...published in the literature. The gasification performance was evaluated under different operating conditions, such as equivalence ratio, temperature, pressure and coal to biomass ratio. It is observed that the lower heating value (LHV) and cold gas efficiency (CGE) increase with increasing temperature until the process reaches a steady state. The effect of pressure on syngas composition is dominant only at non-steady state conditions (<1100 °C). The variation in syngas composition is minor up to the blending of 50% biomass (PB50). However, the PB50 shows a higher LHV and CGE than pure coal by 12%and 18%, respectively. Overall, biomass blending of up to 50% favours gasification performance with an LHV of 12 MJ/kg and a CGE of 78%.
Victorian brown coal, one of the largest and cheapest energy sources in the world, is currently used in mine-mouth coal-fired power plants. These power plants have low efficiency and high CO2 ...emission. Alternative process paths leading to electricity generation and chemical production can provide more energy efficient and environment friendly applications of brown coal. Synthesis of dimethyl ether (DME) from brown coal is an attractive option because of its environmentally benign properties and wide range of applications. This article first reviews the current and likely future applications of brown coal. In the latter part of the article emphasis has been given on DME, since it stands out as a suitable option from both environmental and economic point of view. Finally research needs for the development and commercialisation of DME production process from brown coal has been identified.
Algae have the potential to capture carbon dioxide (CO
2
) and nitric oxide (NO) from flue gases. However, the effects of high concentrations of these gases on the photophysiology of algae are poorly ...understood. To that end, we used the techniques of chlorophyll fluorescence to study the effect of industrially relevant levels of CO
2
and NO on the photophysiology of two green microalgae,
Asterarcys quadricellulare
and
Chlorella sorokiniana
, that are tolerant to these gases. Measurements of maximum quantum yield (
F
v
/
F
m
) and maximum relative electron transport rate (rETR
max
) show an enhanced performance of photosystem II (PSII) under high CO
2
levels. In
C
.
sorokiniana
, high CO
2
stimulated non-photochemical quenching (NPQ), while the opposite effect was observed in
A
.
quadricellulare.
Light-saturated photosynthetic rates (
P
max
) of both species were highest at 10% CO
2
. Further, the tested levels of NO did not show adverse effect on the performance of PSII. OJIP chlorophyll fluorescence transients suggest that in
C
.
sorokiniana
, the energetic communication between PSII units declined at 15% CO
2
. However, in
A
.
quadricellulare
, this decline was visible even at 10% CO
2
with complete inhibition of cell growth at 15% v/v. Overall, our results suggest that although photosynthesis was regulated differently in the two microalga, both species exhibited enhanced PSII performance under reasonably high levels of CO
2
and NO. Thus, the two species are potential candidates for bio-fixation of CO
2
and NO from flue gases.
•Chinese lignite was dried in nitrogen and steam fluidized-bed and microwave.•Ten empirical drying models were employed to simulate the drying kinetic data.•Midilli–Kucuk model best fitted the drying ...data in conventional drying.•Page model described best the microwave drying behavior of lignite.•Drying mechanism is different in conventional and microwave drying methods.
The drying kinetics of Chinese lignite in nitrogen fluidized-bed, superheated steam fluidized-bed and microwave were investigated. The changes in the mass as a function of drying time were measured under various drying conditions. The variations of moisture ratio with time were used to test ten different thin-layer empirical drying models given in the literature. In studying the consistency of all the models, some statistical tests, such as χ2, residual sum of squares (RSS) and F-value were also used as well as coefficient of determination R2. In nitrogen fluidized-bed and superheated steam fluidized-bed, the Midilli–Kucuk model best described the lignite drying process. Drying data in microwave were best described by the Page model, indicative of a difference in kinetics between the two drying methods. This difference was attributed to different heat transfer mechanisms under conventional and microwave drying conditions. The effects of drying parameters in nitrogen fluidized-bed, superheated steam fluidized-bed and microwave drying on the constants and coefficients of the selected models were studied by multiple regression analysis. The apparent diffusion coefficient of moisture in samples was obtained from the kinetics data and the apparent activation energies under nitrogen fluidized-bed, superheated steam fluidized-bed and microwave drying were found to be rather similar.
Display omitted
•Effects of gasifier conditions on the entire system performance are investigated.•The mass ratio of steam/coal has small effects on the overall thermal performance.•An optimal ...operation range exists for the mass ratio of O2/coal.•The carrier gas flow and the CO2 fraction in synthesis gas should be kept at a low level.
The operating conditions of coal gasifier have significant effects on the overall system performance of an associated process. This study designs a methanol-electricity polygeneration system and presents a comprehensive discussion about the effects of the ratio of steam to coal, the ratio of O2 to coal, the ratio of carrier gas (CO2) to coal and the CO2 concentration in methanol synthesis gas on different performance indicators. The results show that the steam/coal ratio has slight effects on the overall system performance due to the offset in different sections. An optimal O2/coal ratio exists in the range of 0.84–0.86 to achieve the minimum unit water consumption and the maximum methanol production and energy efficiency, which is almost consistent with the range that the H2 concentration in gasifier syngas reaches the maximum value. The amount of carrier gas CO2 and the CO2 concentration in methanol synthesis gas should be kept at a low level to just meet the requirements of coal pressurization and synthesis reaction. This comprehensive sensitivity analysis can provide some significant guidance for the system design.
PDF
