Energy nexus最新文献

As global energy demand continues to rise, the imperative to explore and enhance energy generation from existing resources intensifies. Combined cycle power plants (CCPPs) have emerged as a promising solution to improve efficiency and electricity production. In this study, we present a comprehensive analysis of the thermodynamic performance of a 750 MW CCPP located in Assiut, Egypt, with a focus on its energy and exergy efficiency. Our investigation reveals critical insights into the CCPP's operational dynamics. Notably, the combustion chambers emerge as the primary contributors to exergy destruction, accounting for 53.3 % of the total exergy loss. Heat recovery steam generators (HRSGs) follow closely at 32 %, while compressors, steam turbines, gas turbines, and cooling systems contribute 5.3 %, 5 %, 2.3 %, and 1.7 %, respectively. These findings pinpoint specific areas where exergy losses are most significant, offering valuable guidance for targeted improvements in CCPP performance. Furthermore, we report that the overall energy efficiency of the entire plant stands at 34.6 %, with an exergy efficiency of 33.5 %. In summary, our study provides a comprehensive scientific assessment of the thermodynamic performance of a 750 MW CCPP. The specific insights into exergy destruction and efficiency metrics not only contribute to our understanding of CCPPs but also offer actionable recommendations for optimizing the operation of gas turbine based CCPPs. These findings hold significance in the broader context of energy sustainability and environmental considerations.

For a wide spectrum of agricultural market participants, building price forecasts of various agricultural commodities has always been a vital project. In this work, we approach this problem for the weekly wholesale price index of edible oil in the Chinese market during a ten-year period of January 1, 2010–January 3, 2020 through the exploration of the non-linear auto-regressive neural network as the forecast model. Specifically, we investigate forecast performance stemming from different settings of models, which include considerations of training algorithms, hidden neurons, delays, and how the data are segmented. With the analysis, a relatively simple model is constructed and it produces performance that is rather accurate and stable. Particularly, performance in terms of relative root mean square errors is 2.80%, 3.01%, and 1.80% for training, validation, and testing, respectively. Forecast results here could be utilized as part of technical analysis and/or combined with other fundamental forecasts as part of policy analysis.

Seed germination is critical for seedling procedures, and new technologies are required to increase crop yields. Some substances are considered elicitors or stimulating agents because they promote seed germination as well as plant growth (like root and plumule length, and germination rate among others). Some of these, could be applied during plant growth, or in earlier phases before germination as seeds pretreatment. Neutral electrolyzed water (NEW) is a solution of oxidizing agents mainly studied for its antimicrobial power mainly applied to food pathogens, and in less reports to phytopathogens. The objective of this work is to evaluate the effect of NEW on germination and morphological parameters of tomato (Lycopersicon esculentum), cucumber (Cucumis sativus) and lettuce (Lactuca sativa L.) seeds as well as to evaluate the in vitro activity of NEW against F. oxysporum. Two experiments were carried out to determine the in vitro and in vivo effects of NEW in seed pretreatment and another in vitro experiment was also carried out to determine antifungal effect against F. oxysporum. NEW in vitro treatments at 50 mg/L decreased spore concentration greater than 4 log spores/mL. Germination parameters and morphological variables were analyzed after NEW pretreatments. For in vitro germination, NEW pretreatments up to 75 mg/L did not show effect on germination parameters however highest dose was slightly adverse (4 % against water control). For in vivo germination, NEW pretreatment of 100 mg/L had a stimulating effect on the germination rate in cucumber seeds (100 % FGP against 83 % FGP for water control). For tomato seeds germination neither stimulate nor adverse effect was observed (same percentage as water control). For lettuce seeds germination an inhibitory effect for 12 and 24 h of exposure time was achieved (73 % NEW treatment against 90 % of water control). For tomato and lettuce seeds, the NEW pretreatment of 50 mg/L during 12 h increased its germination capacity.

The ongoing climate change threat brought by the increase of carbon dioxide (CO₂) emissions in the atmosphere has rekindled global activism to address its detrimental effects on agricultural production with the maximum tenacity. The current study, consequently, examines the causal effect between CO₂ emissions and agricultural production indexes while controlling for renewable energy consumption, arable land and governance, using data spanning from 1996 to 2019. The study applied pooled mean group/Autoregressive distributed lag and fixed effect approaches and tested for the causality between the variable of interest using the Dumitrescu and Hurlin Granger non-causality test. The long-run equation shows that CO₂ emissions, renewable energy consumption, labour force and arable land size have positive effects on the crop production index. Whereas, renewable energy consumption, labour force, arable land size and governance positively affect the livestock production index. While no causality exists between CO₂ emissions and crop production index. However, the effects of governance and the size of arable land on agricultural production remained inconclusive. To achieve the UN Sustainable Development Goal of zero hunger for their people, East African Community countries need to commercialize agricultural production and embrace more eco-friendly farming techniques.

Rice straw (RS) is a rich lignocellulosic biomass that can be employed for biogas generation through anaerobic digestion. However, lignin-silica encrustation around the holocellulose complex hinders its digestibility. Therefore, in this present study, RS was biologically pretreated with microbial consortium of Punjab Agricultural University (PAU decomposer), which is composed of Bacillus sp., Delftia sp., Pseudomonas sp., Lysinibacillus fusiform, Arthrobacter nicotianae, Paenibaccilus ehimensis, Aspergillus sp. and Trichoderma sp. Bio-digested slurry, the underutilized spent waste from cattle dung-based biogas plants was used as a growth medium for the mass multiplication of consortium. Soaked and chopped RS was pretreated with consortium and individual cultures in triplicate sets for 5 and 10 d and were analyzed for biochemical parameters along with cellulolytic activity. The pretreated straw was used for biogas production in 2 L capacity anaerobic digesters. Cellulolytic activities i.e., endoglucanase (0.071 IU/mL), exoglucanase (0.027 IU/mL) and β-glucosidase (3.734 IU/mL) of consortium treated RS were higher as compared to untreated RS. Biogas production from consortium pretreated RS was 187.45 L/kg RS which is 45.93% more as compared to untreated RS with 128.45 L/kg RS of biogas. This could be attributed to the synergistic cellulolytic activities of PAU decomposer leading to enhanced biogas production from RS.

Tea plant (Camellia sinensis L.) is an economically important beverage crop cultivated worldwide. Tea is the most popular non-alcoholic beverage, which is manufactured from fresh shoots of tea plants. The aroma, taste and color of tea are the most important index for determining tea quality. Manipulating light transmission by shading is the most effective method of improving the nutritional value and sensory qualities of tea. Shading on tea plant enhances the taste and aroma of tea by affecting the synthesis of free amino acids, flavonoids and aromatic compounds. Also, shading can significantly increase the chlorophyll content of tea leaves, leading to enhanced tea leaf coloration. Thus, the expression of genes related to chlorophyll biosynthesis, free amino acids biosynthesis and flavonoids biosynthesis pathways are significantly regulated by shading treatment to increase the overall quality of tea plants. However, the shading-induced regulatory mechanism remains unclear. Therefore, this review summarizes up to date knowledge of the shading effects on chlorophyll, carotenoid and quality-related metabolites biosynthesis for improvement of taste, aroma and color quality of green tea.

This study presents the synthesis and characterization of a highly effective nanocomposite material, CeO₂@starch, designed for the removal of Cr(VI) from aqueous solutions. Through a series of experiments and analyses, we investigated the adsorption efficiency of the CeO₂@starch nanocomposite by considering various factors such as contact duration, pH levels, initial Cr(VI) concentration, and temperature. Firstly, we successfully synthesized the CeO₂@starch nanocomposite and conducted comprehensive characterizations using BET, FTIR, and SEM analyses. These characterizations provided valuable insights into the structure and properties of the nanocomposite, confirming its potential as a promising adsorbent for Cr(VI) removal. In our experiments, we observed that the CeO2@starch nanocomposite exhibited an impressive capacity for reducing Cr(VI) ions to Cr(III) in aqueous solutions. Notably, the adsorption efficiency was found to be at its maximum at pH 2, and equilibrium was achieved within 240 min of contact time. The kinetics of the adsorption process were accurately described by the pseudo 1st order equation, which displayed a high correlation coefficient (greater than 0.99), indicating the reliability of this model. Furthermore, we compared various adsorption isotherm models to describe the data obtained, including Freundlich, Sips, Redlich-Peterson, Temkin, and Langmuir models. The Langmuir isotherm model demonstrated the best fit, emphasizing the monolayer adsorption of Cr(VI) onto the CeO₂@starch nanocomposite and confirming its superior performance compared to other models. The Langmuir adsorption capacity of the nanocomposite material was measured at 22℃ and found to be 48.54 mg/g. Interestingly, the adsorption capacity increased with higher temperatures, suggesting an endothermic adsorption process. To gain further insights into the nature of the adsorption, we performed thermodynamic analysis, revealing that the adsorption of hexavalent Cr onto the CeO₂@starch nanocomposite was spontaneous and had a chemical nature.

This research aims to compare the energy output potential of land-based and floating bifacial photovoltaic (PV) systems of 50 MW and 400 kW with an existing land-based and floating monofacial PV system of the same dimensions and design in Bui, Ghana. The study uses ground weather files and PV system configurations to compare the energy yield from simulations of the different PV systems based on capacity factor, performance ratio, and monthly, final/annual energy yield. The results show that the bifacial gain of land-based and floating bifacial PV systems is 2.51% and 4.57%, respectively, and the capacity factor and performance ratio of the bifacial PV system are higher than the monofacial PV system. However, the additional energy generated by the bifacial PV system is not significant enough to justify the installation of a new system. Therefore, the study recommends optimizing system parameters such as albedo, tilt angle, and ground cover ratio to 0.5, 15°, and 0.3 respectively to enhance the performance and increase the bifacial gain of the PV system. Overall, this study provides valuable insights into the potential of bifacial PV systems in Bui, Ghana, and highlights the importance of optimizing system parameters for maximum energy output.

The composition of atmospheric precipitation, an important criterion considered to account for air pollution, is usually determined with respect to wet precipitation and dry precipitation, or as bulk deposition in combined form. Although rainwater quality should be continuously monitored in order to understand the extent of air pollution, such investigation lacks attention in Sri Lanka. This study was thus aimed to determine the composition of bulk deposition collected weekly for a period of eleven months from February to December 2019, in three sampling locations; namely the University of Peradeniya (UOP), Kandy City Central (KCC) and Polgolla. Parameters quantitatively determined, rainfall, pH, conductivity, salinity, total dissolved solids (TDS), hardness, anions: Cl⁻, NO₃⁻, SO₄²⁻, F⁻, PO₄³⁻ and trace metals: Zn, Fe, Al, Mn, Cu, Pb, Cr, using standard analytical methods indicated that the KCC site showed the overall highest degree of air pollution followed by UOP and Polgolla sites. Nevertheless, no acid rain occurrences were observed during the sampling period in any of the three sites according to pH measurements. Anions of bulk deposition showed the sequence Cl⁻> SO₄²⁻ > NO₃⁻in all three sites with Cl⁻and SO₄^2- being dominant anions. Furthermore, trace metals of bulk deposition showed the sequence, Zn > Fe > Al > Mn > Cu > Pb, in all three sites. Bulk precipitation data analyzed using Pearson correlation showed high positive significant correlations between conductivity and salinity, conductivity and TDS, and salinity and TDS, among all water quality parameters. Among trace metals, the highest positive significant correlation was found to be between Fe and Mn at the UOP Site. The highest positive significant correlation was between Al and Zn at the KCC site. No correlation between trace metals was found at the Polgolla Site.

Access to sources of cooking energy has potential impacts on food security, however, there is a paucity of information and empirical evidence on their linkages. This study sought to ascertain the impacts of access to cooking energy on household food security in Nigeria, using the nationally representative Living Standards Measurement Study data. The data covered the period 2010/2011 to 2015/2016. The Household Dietary Diversity Score (HDDS), and the Household Food Insecurity Access Scale (HFIAS) were used to measure household food security, while the major cooking fuel type utilized by households was used as a proxy for cooking energy access. To unravel the effects of access to different cooking energy sources on food security, inferential analysis was conducted using the Generalized Estimating Equations (GEE). The findings of the study revealed that traditional/biomass (firewood, grass and charcoal) cooking energy sources are still widely used by households across Nigeria. The empirical analysis showed that households that use transition and clean cooking energy sources were eating more diverse diets than those that use biomass. Furthermore, households using clean cooking energy sources had lower HFIAS than those using biomass. It is imperative that more households in Nigeria should have improved access to cleaner sources of cooking energy to reduce carbon emissions and enhance health outcomes, and food and nutrition status. This will significantly improve the national food security outlook, and foster the attainment of national and SDG (2 and 7) goals.