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Abstract Bitumen recovery by steam-solvent coinjection involves the coupled thermal/compositional mechanisms for reduction of bitumen viscosity. Reliable design of such processes requires reservoir flow simulation based on a proper phase-behavior model so that the oleic-phase viscosity near the steam-chamber edge can be modeled reliably. However, the effect of bitumen characterization (e.g., the number of pseudo components used) on steam-solvent coinjection simulation has not been studied in detail, and can be realized only after running multiple reservoir simulations, which is time consuming. There are two main objectives in this paper. One is to develop a reliable method for bitumen characterization by improving the fluid characterization method that was recently developed based on perturbation from n-alkanes (PnA). The other is to develop a novel analytical method for assessing the sensitivity of a particular coinjection simulation to bitumen characterization without having to perform reservoir simulations. A simulation case study is given to validate this analytical method. A proper number of pseudo components for bitumen characterization cannot be determined without considering the effect of phase behavior on the oleic-phase viscosity at chamber-edge conditions in steam-solvent coinjection simulation. Results show that the analytical method developed in this research can detect the sensitivity of recovery simulation to bitumen characterization without performing multiple flow simulations using different sets of fluid models. The PnA-based method developed for bitumen characterization gives reliable predictions of phase behavior for bitumen/solvent mixtures with a small amount of experimental data.

Abstract The development of predictive mathematical models for water management in polymer electrolyte membrane fuel cells requires detailed understanding of water distribution and water transport across the Nafion layer. The anisotropic microstructure of Nafion suggests the measurement of water content and mass transport should be along the fuel cell functional direction, i.e. across the membrane. Non-invasive, high resolution, microscopy measurements of this type are very challenging. We report here the calibration of a minimal mathematical model for diffusive water transport in Nafion against data from high-resolution water content maps determined with a new magnetic resonance imaging methodology developed for this purpose. A mock fuel cell was designed to permit well-controlled wetting and drying boundary conditions. With no chemical potential driving force involved, we assume the water transport behavior will be dominated by diffusion. Moreover we show that, in this context, our model is mathematically equivalent to the traditional permeation models based upon saturation dependent pressure gradients via a capillary pressure ansatz. The non-linear equilibrium water distribution across the Nafion membrane measured in this work suggests a bi-modal diffusivity. The model constructed associates distinct transport behaviors to water contents above and below a critical threshold, consistent with a rearrangement of a micro-structural pore network. The experimental observation and the model prediction agree with the primary features of Weber's model of Nafion, which predicts distinct modes of transport for hydration fronts traversing the through-plane direction of the membrane.

Abstract The accumulation of waste biomass and plastic and the inefficient combustion of low-quality coal is a major cause of energy loss and air pollution in rural China. This paper reports for the first time an experimental and multi-perspective analysis on an industrial scale co-pyrolysis of waste biomass and plastic. The results show that the resulting biochar product had a low calorific value of ≥21.0 MJ/kg, which meets the national standard for commercial solid fuel (GB/T 31862–2015). The calorific value of the produced gas was over 10 MJ/m3 and met the requirements of the national standard for residential heating and cooking (GB/T 13612–2006). The products of the co-pyrolysis can replace 1100 t of standard coal per annum, and reduce carbon dioxide emissions, sulfur dioxide emissions, smoke, and other contaminants at the rate of 1720 t, 5–6 t, and 320 kg, respectively, as well as reducing smoke pollution. In addition, through the recycling of 750 t of plastic waste per annum for use in the co-pyrolysis, this method can reduce the white pollution of 50–66.7 km2 of farmland in the local area. The present study can guide the optimization of such systems and lead to adequate flexibility in the co-pyrolysis of different wastes to generate economic and socioenvironmental benefits.

The global energy demand is growing substantially. Clean and secure energy supply is a must for our civilization's sustainable development. Solar and wind energy is growing fast and can contribute significantly to meet the goals set by many countries to reduce greenhouse gas emissions. A deep and wide investigation of the environmental impact of solar and wind energy is important before any solar or wind plants' construction is made. In this study, the literature is reviewed to summarize the environmental impact of solar and wind energy systems in terms of the following factors; land use, water consumption, impact on biodiversity, visual and noise effects, health issues, and impact on micro climate. Although the benefits of solar and wind energy are obvious and great, negative perception of these technologies can inhibit their wide penetration in some regions. This review paper includes a critical and an inclusive analysis of solar and wind energy’s environmental impact and may serve as an important tool to conduct a proper environmental impact assessment. This critical analysis may serve also as a tool for developers, policy, and decision-when planning future solar and wind farms.

Abstract In this study, hydrogen production with activated sludge, a diverse bacterial source has been investigated and compared to microflora from anaerobic digester sludge, which is less diverse. Batch experiments were conducted at mesophilic (37 °C) and thermophilic (55 °C) temperatures. The hydrogen production yields with activated sludge at 37 °C and 55 °C were 0.56 and 1.32 mol H 2 /mol glucose consumed, respectively. While with anaerobically digested sludge hydrogen yield was 2.18 mol H 2 /mol glucose consumed at 37 °C and 1.25 mol H 2 /mol glucose consumed at 55 °C. The results of repeated batch experiments for 615 h resulted in average yields of 1.21 ± 0.62 and 1.40 ± 0.16 mol H 2 /mol glucose consumed for activated sludge and anaerobic sludge, respectively. The hydrogen production with activated sludge was not stable during the repeated batches and the fluctuation in hydrogen production was attributed to formation of lactic acid as the predominant metabolite in some batches. The presence of lactic acid bacteria in microflora was confirmed by PCR-DGGE.

The effect of thermal pre-treatment on sludge anaerobic digestion (AD) efficiency was studied at different total solids (TS) concentrations (20.0, 30.0 and 40.0 g TS/L) and digestion times (0, 5, 10, 15, 20 and 30 days) for primary, secondary and mixed wastewater sludge. Moreover, sludge pre-treatment, AD and disposal processes were evaluated based on a mass-energy balance and corresponding greenhouse gas (GHG) emissions. Mass balance revealed that the least quantity of digestate was generated by thermal pre-treated secondary sludge at 30.0 g TS/L. The net energy (energy output-energy input) and energy ratio (energy output/energy input) for thermal pre-treated sludge was greater than control in all cases. The reduced GHG emissions of 73.8 × 10(-3) g CO2/g of total dry solids were observed for the thermal pre-treated secondary sludge at 30.0 g TS/L. Thermal pre-treatment of sludge is energetically beneficial and required less retention time compared to control.

La cuenca hidrográfica de Ikkour situada en la montaña del Atlas Medio (Marruecos) ha sido objeto de graves problemas de erosión del suelo. Este estudio tuvo como objetivo evaluar la susceptibilidad a la erosión del suelo en esta cuenca montañosa utilizando la Ecuación Universal de Pérdida de Suelos (USLE) e índices espectrales integrados con el entorno del Sistema de Información Geográfica (SIG). El modelo USLE requirió la integración de mapas de factores temáticos que son la agresividad de la lluvia, la longitud y la pendiente del talud, la cobertura vegetal, la erosionabilidad del suelo y las prácticas de control de la erosión. Estos factores se calcularon utilizando datos de teledetección y SIG. La evaluación basada en USLE mostró que la pérdida potencial de suelo anual total estimada fue de aproximadamente 70,66 toneladas ha-1 año-1. Esta pérdida de suelo se ve favorecida por las pendientes pronunciadas y la cubierta vegetal degradada. El método del índice espectral, que ofrece una evaluación cualitativa de la erosión hídrica, mostró diferentes grados de degradación del suelo en la cuenca del estudio según FI, BI, CI y NDVI. Los resultados de este estudio mostraron un acuerdo entre el modelo USLE y el enfoque del índice espectral, e indicaron que la tasa de erosión del suelo prevista puede deberse a la topografía más accidentada de la tierra y al aumento de las áreas agrícolas. De hecho, estos resultados pueden ayudar aún más a los responsables de la toma de decisiones en la implementación de un programa de protección adecuado para reducir la erosión del suelo. Le bassin versant d'Ikkour situé dans la montagne du Moyen Atlas (Maroc) a fait l'objet de graves problèmes d'érosion des sols. Cette étude visait à évaluer la sensibilité à l'érosion des sols dans ce bassin versant montagneux à l'aide de l'équation universelle de perte de sol (USLE) et d'indices spectraux intégrés à l'environnement du système d'information géographique (SIG). Le modèle USLE a nécessité l'intégration de cartes de facteurs thématiques qui sont l'agressivité des précipitations, la longueur et la pente de la pente, la couverture végétale, l'érodabilité des sols et les pratiques de contrôle de l'érosion. Ces facteurs ont été calculés à l'aide de données de télédétection et de SIG. L'évaluation basée sur l'USLE a montré que la perte potentielle totale annuelle estimée des sols était d'environ 70,66 tonnes ha−1 an−1. Cette perte de sol est favorisée par les pentes abruptes et la couverture végétale dégradée. La méthode de l'indice spectral, offrant une évaluation qualitative de l'érosion hydrique, a montré différents degrés de dégradation des sols dans le bassin versant d'étude selon FI, BI, CI et NDVI. Les résultats de cette étude ont montré un accord entre le modèle USLE et l'approche de l'indice spectral, et ont indiqué que le taux d'érosion du sol prédit peut être dû à la topographie des terres les plus accidentées et à une augmentation des zones agricoles. En effet, ces résultats peuvent aider davantage les décideurs à mettre en œuvre un programme de conservation approprié pour réduire l'érosion des sols. The Ikkour watershed located in the Middle Atlas Mountain (Morocco) has been a subject of serious soil erosion problems. This study aimed to assess the soil erosion susceptibility in this mountainous watershed using Universal Soil Loss Equation (USLE) and spectral indices integrated with Geographic Information System (GIS) environment. The USLE model required the integration of thematic factors' maps which are rainfall aggressiveness, length and steepness of the slope, vegetation cover, soil erodibility, and erosion control practices. These factors were calculated using remote sensing data and GIS. The USLE-based assessment showed that the estimated total annual potential soil loss was about 70.66 ton ha−1 year−1. This soil loss is favored by the steep slopes and degraded vegetation cover. The spectral index method, offering a qualitative evaluation of water erosion, showed different degrees of soil degradation in the study watershed according to FI, BI, CI, and NDVI. The results of this study displayed an agreement between the USLE model and spectral index approach, and indicated that the predicted soil erosion rate can be due to the most rugged land topography and an increase in agricultural areas. Indeed, these results can further assist the decision makers in implementation of suitable conservation program to reduce soil erosion. كان مستجمع مياه إيكور الواقع في جبل الأطلس الأوسط (المغرب) موضوعًا لمشاكل خطيرة تتعلق بتآكل التربة. تهدف هذه الدراسة إلى تقييم حساسية تآكل التربة في مستجمعات المياه الجبلية هذه باستخدام معادلة فقدان التربة العالمية (USLE) والمؤشرات الطيفية المتكاملة مع بيئة نظام المعلومات الجغرافية (GIS). يتطلب نموذج USLE تكامل خرائط العوامل المواضيعية وهي شدة هطول الأمطار، وطول المنحدر وانحداره، والغطاء النباتي، وقابلية تآكل التربة، وممارسات مكافحة التعرية. تم حساب هذه العوامل باستخدام بيانات الاستشعار عن بعد ونظم المعلومات الجغرافية. أظهر التقييم القائم على USLE أن إجمالي الخسارة السنوية المحتملة للتربة كان حوالي 70.66 طن هكتار-1 سنة-1. ويفضل فقدان التربة هذا المنحدرات الشديدة والغطاء النباتي المتدهور. أظهرت طريقة المؤشر الطيفي، التي تقدم تقييمًا نوعيًا للتآكل المائي، درجات مختلفة من تدهور التربة في مستجمعات المياه في الدراسة وفقًا لـ FI و BI و CI و NDVI. أظهرت نتائج هذه الدراسة وجود اتفاق بين نموذج USLE ونهج المؤشر الطيفي، وأشارت إلى أن معدل تآكل التربة المتوقع يمكن أن يكون بسبب تضاريس الأراضي الأكثر وعورة وزيادة في المناطق الزراعية. في الواقع، يمكن أن تساعد هذه النتائج صناع القرار بشكل أكبر في تنفيذ برنامج الحفظ المناسب للحد من تآكل التربة.

A highly unconsolidated undersaturated reservoir producing heavy oil with an API of 12.1° is located in Lindbergh Field of Elk Point area, Alberta, Canada. A specific well in this reservoir was initially designed to produce oil via a cold heavy oil production with sand (CHOPS) mechanism. However, a large amount of the sand production on a daily basis plugged the progressive cavity pump installed in the well. The cost of well services to unplug the pump on a monthly basis exceeded the revenue from produced oil, and thus, the well was considered uneconomic. Various techniques have been sought to control the sand production and to increase the cumulative oil production and the pump efficiency. Installing screens and meshes in the production interval of the wellbore was analyzed as a solution to the sand production. Installing screens increased the skin factor and resulted in a very low production rate of 0.15 m3/day. The cost of purchasing and installing screens was estimated to be approximately $87,650 with five shut-in days. In addition, the screens also needed further sand clean up, which is an expensive process. Hence, the screens were not recommended for this candidate well. A Back-pressure regulator (BPR) is currently installed on the casing of the well. The initial purpose of installing BPR on the casing was to control the wellbore pressure. The BPR restricts the flow of gas vented through the casing-tubing annulus. This study analyzes the effects of restricting flow of the vented gas such as solution gas reduction, which causes (i) higher settling velocity for the sand grain, (ii) lower Basic sediment and water (BS&W), and (iii) lower in situ oil density. The production data of candidate well obtained from AccuMap (v.18.12) shows that the production hours increased significantly after installing BPR. This is because the number of well services reduced by 90 %. This results in an approximately $34,000 per month increase in profit (assuming $30.00/barrel of oil) for each well. This shows one million dollars savings on a monthly basis when the application of the BPR installation is implemented on 30 similar wells. The cost of the BPR installed on well is $328.00, and there is no operating cost involved since the cost of additional, necessary maintenance and operation is nearly negligible. Moreover, this study provides the field examples of improper BPR operation, which resulted in economic loss. Possible solutions to fix the improper installation of BPR are proposed as well.