• Energy Research
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Agricultural land acquisition for urbanization (ALAFU) has strongly impacted agriculture in Vietnam during the last decades. Given the mixed data obtained from a survey (with 50 households who lost 50% of their farmland area), in-depth interviews, a group-focused discussion and observation, this study shows the different impacts of ALAFU on each agricultural activity of affected household by comparing before and after ALAFU. Rice cultivation and animal breeding have sharply declined, but potted flower plantation (PFP) has quickly grown and is the main income of 34% of surveyed households. Rice cultivation has declined not only as a result of agricultural land acquisition, which has resulted in the loss of rice land, but also as a result of urbanization, which has resulted in rice land abandonment. Conversely, PFP is growing due to advantages associated with urbanization, such as a good consumer market and upgraded infrastructure. However, whether they are declining or increasing, all agricultural activities have to face challenges related to the shortcomings in agricultural land allocation and agricultural development plans. This study suggests that if ALAFU projects are continued, the government should evaluate agricultural development and forecast farmland abandonment after ALAFU. Simultaneously, they should put more effort into maintaining agriculture in the form of peri-urban or urban agriculture, which is significant for sustainable development in affected communities.

AbstractWe develop a novel approach to analysing decarbonisation strategies by linking global resource inventories with demographic systems. Our ‘mine-town systems’ approach establishes an empirical basis for examining the spatial extent of the transition and demographic effects of changing energy systems. The research highlights an urgent need for targeted macro-level planning as global markets see a decline in thermal coal and a ramp up of other mining commodities. Our findings suggest that ramping up energy transition metals (ETM) could be more disruptive to demographic systems than ramping down coal. The data shows asymmetry in the distribution of risks: mine-town systems within the United States are most sensitive to coal phase-out, while systems in Australia and Canada are most sensitive to ETM phase-in. A complete phase-out of coal could disrupt demographic systems with a minimum of 33.5 million people, and another 115.7 million people if all available ETM projects enter production.

To address the challenges associated with wind power integration, this paper analyzes the impact of distributed renewable energy on the voltage of the distribution network. Taking into account the fast control of photovoltaic inverters and the unique characteristics of photovoltaic arrays, we establish an active distribution network voltage reactive power-optimization model for planning the active distribution network. The model involves solving the original non-convex and non-linear power-flow-optimization problem. By introducing the second-order cone relaxation algorithm, we transform the model into a second-order cone programming model, making it easier to solve and yielding good results. The optimized parameters are then applied to the IEEE 33-node distribution system, where the phase angle of the node voltage is adjusted to optimize the reactive power of the entire power system, thereby demonstrating the effectiveness of utilizing a second-order cone programming algorithm for reactive power optimization in a comprehensive manner. Subsequently, active distribution network power quality control is implemented, resulting in a reduction in network loss from 0.41 MW to 0.02 MW. This reduces power loss rates, increases utilization efficiency by approximately 94%, optimizes power quality management, and ensures that users receive high-quality electrical energy.

Abstract This review paper summarizes recent advances and challenges in the assessment of rock behavior and performance in deep low-permeability and high-temperature geothermal reservoirs. Geothermal energy systems for electricity production target deep rock between ca. 2 km and 5 km depth to obtain sufficiently elevated temperatures. Rock permeability enhancement faces many challenges, and therefore the development of Enhanced Geothermal Systems (EGS) still represents a pioneering effort. The potential and advantage of EGS above conventional geothermal reservoirs is its independence of the location that supplies sufficient heat and fluid. Several issues prevent the successful application of EGS technology. First, the effects of non-uniform in-situ stresses and loading history on rock fracturing are not well understood. Second, the role of rock anisotropy, heterogeneity and thermal effects on rock properties in the design of hydraulic fracturing operations is not clear. Third, the reduction of induced seismicity effects raises safety and public acceptance issues. This manuscript formulates outlines for future research directions. Specifically, the recommendations focus on the development of tools for better understanding and mitigating problems, which occur during stimulation of deep geothermal reservoirs.

AbstractReview: use of manganese complexes in substitution and annulation reactions of arenes nvolving directed C‐H activation; 167 refs.

Based on a substantially larger data set (in both regional and temporal coverage) than the existing literature, we investigate the theoretically ambiguous link between income inequality and per capita emissions using cross-country panel data. We find that the relationship depends on the level of income. Using an arguably superior group-fixed effects estimator, we show that for low and middle-income economies, higher income inequality is associated with lower carbon emissions while in upper middle-income and high-income economies, higher income inequality increases per capita emissions. The result is robust to the inclusion of plausible transmission variables as well as different data sources or aggregations.

In fractured reservoirs characterized by low matrix permeability, fracture networks control the main fluid flow paths. However, in layered reservoirs, the vertical extension of fractures is often restricted to single layers. In this study, we explored the effect of changing marl/shale thickness on fracture extension using comprehensive field data and numerical modeling.The field data were sampled from coastal exposures of Liassic limestone-marl/shale alternations in Wales and Somerset (Bristol Channel Basin, UK). The vertical fracture traces of more than 4000 fractures were mapped in detail. Six sections were selected to represent a variety of layer thicknesses. Besides the field data also thin sections were analyzed. Numerical models of fracture extension in a two-layer limestone-marl system were based on field data and laboratory measurements of Young's moduli. The modeled principal stress magnitude σ3 along the lithological contact was used as an indication for fracture extension through marls. Field data exhibit good correlation (R2 = 0.76) between fracture extension and marl thickness, the thicker the marl layer the fewer fractures propagate through. The model results show that almost no tensile stress reaches the top of the marl layer when the marls are thicker than 30 cm. For marls that are less than 20 cm, the propagation of stress is more dependent on the stiffness of the marls. The higher the contrast between limestone and marl stiffness the lower the stress that is transmitted into the marl layer. In both model experiments and field data the critical marl thickness for fracture extension is ca. 15–20 cm.This quantification of critical marl thicknesses can be used to improve predictions of fracture networks and permeability in layered rocks. Up- or downsampling methods often ignore spatially continuous impermeable layers with thicknesses that are under the detection limit of seismic data. However, ignoring these layers can lead to overestimates of the overall permeability. Therefore, the understanding of how fractures propagate and terminate through impermeable layers will help to improve the characterization of conventional reservoirs. Keywords: Boundary element modelling, Marl/limestone multilayer, Layer thickness and stiffness control, Permeability, Fractured reservoirs