Energy nexus最新文献

The acid-modified chilli peppers, a novel adsorbent, were prepared and used to absorb Ni(II) and Cd(II) ions from aqueous solution. Batch experiments with raw chilli peppers were compared with those of acid-modified chilli peppers. Batch experiments were conducted to evaluate the adsorption capacities of both sorbents under different conditions, including pH, concentration, contact time and temperature, in solutions. Bands with oxygen groups (-OH, -COOH, -C = O, -COC and -CO) on both sorbents were identified by Fourier transform infrared spectroscopy. Scanning electron micrographs of raw chilli peppers showed a morphology resembling spheres, while acid-modified chilli peppers showed a structure resembling a mesh of a mixture of different shapes, including squares and triangles. Maximum sorption capacities were achieved at pH 7, with the uptake of Ni(II) and Cd(II) ions dependent on pH.

The highest adsorption capacities for raw chilli peppers and acid-modified chilli peppers were observed at 70 °C. The sorption capacities increased with increasing temperature. The concentration effect showed that as the concentration of Ni(II) and Cd(II) ions increased on raw chilli peppers and acid-modified chilli peppers, the adsorption capacity also increased. On raw chilli peppers, the rate of removal of Ni(II) and Cd(II) ions in solution was 60 min, while on acid-modified chilli peppers it took 80 min. The adsorption of Ni(II) and Cd(II) ions was best described by the Freundlich model with heterogeneous coverage and maximum capacities of 45.33 and 39.12 mg/g, respectively. The uptake of Ni(II) and Cd(II) ions was endothermic and showed positive values (∆Hº). Gibb′s free energy (∆Gº) for Cd(II) and Ni(II) ions on the activated carbon showed that the reaction was spontaneous. The change in entropy (ΔS^o) of the reactions showed positive magnitudes for both pollutants, indicating a high degree of randomness in the solid-liquid phase. The kinetic model that best fitted the mechanism was pseudo-first order for Ni(II) and Cd(II) ions, indicating correlation numbers of R² values of 0.9923–0.9995. Therefore, the acid-modified chilli peppers can be used as a viable alternative adsorbent for effective removal of Cd(II) and Ni(II) ions from aqueous solution.

Sugarcane trash is a source of biomass available for energy generation. However, this potential has not been explored in the South African small-scale sugarcane sector. The current trash management practices of farmers, especially, pre-harvest burning, have huge negative environmental implications. Sustainable management of sugarcane trash could help address several challenges in the sugarcane industry including the high cost of irrigation. Therefore, this study is meant to assess small-scale growers’ trash management practices and their implications on greenhouse gas emissions. It also ascertains the potential for using sugarcane trash in the co-generation of electricity. The study was conducted in two communities in KwaZulu-Natal and Mpumalanga provinces with 330 small-scale farmers. A probit regression was used to determine factors that influence farmers’ trash management practices. Other analyses such as estimations of the amount of available trash, burning emissions and potential energy from sugarcane were informed by previous studies. The findings showed that pre-burning of sugarcane is a common practice among smallholder producers in South Africa. However, some farmers have attempted to move away from this practice opting to leave their sugarcane in the field or use it for compost. The farmers’ burning of sugarcane releases an estimated 0.08 tCO2-e per ha into the atmosphere. In total, the estimated greenhouse gas emissions from sugarcane burning of all small-scale growers in the two provinces are 725 tCO2-e per annum. The findings also revealed that having more land, poor endowment with psychological capital, lack of access to extension, limited resources, and working in silos compound the practice of burning sugarcane. The estimated energy potential from small-scale sugarcane producers in the country, using a 50 % recovery efficiency and 36 % energy conversion efficiency is 150,323.3 MWh. The study proposes several recommendations for improving trash management practices and initiating the co-generation of electricity from trash in the small-scale sugarcane industry.

Oil prices play a pivotal role in Thailand's economic development due to its heavy reliance on oil imports to meet its energy needs. Fluctuations in global oil prices directly and significantly impact domestic price levels, affecting production costs, inflation, and overall economic growth. To ensure stability and foster economic development, it is crucial to comprehend and effectively manage these dynamics. Therefore, this study aims to assess the impact of global oil prices on domestic price levels in Thailand, including key indexes such as the producer price index, consumer price index, and export price index, as well as prices of essential commodities like oil palm, sugarcane, cassava, diesel, and gasohol. The study employs both linear and nonlinear ARDL specifications, analyzing monthly time series data from January 2005 to June 2023 to unveil the nature of the relationship between global oil prices and product price levels. The empirical results indicate that most product prices respond to changes in global oil prices in an asymmetrical manner. However, oil palm prices exhibit a symmetrical response, and sugarcane prices do not display a clear pattern during testing. Based on these findings, the study offers recommendations for short-term and long-term policies aimed at mitigating the impact of domestic oil price fluctuations, ensuring energy stability, and promoting sustainability in the future.

Introduction

Liquefied petroleum gas (LPG) is a clean cooking fuel that emits less household air pollution (HAP) than polluting cooking fuels (e.g. charcoal, wood). While switching from polluting fuels to LPG can reduce HAP and improve health, the impact of ‘stacking’ (concurrent use of polluting fuels and LPG) on adverse health symptoms (e.g. headaches, eye irritation, cough) among female cooks is uncertain.

Methods

Survey data from the CLEAN-Air(Africa) study was collected on cooking patterns and health symptoms over the last 12 months (cough, wheezing, chest tightness, shortness of breath, eye irritation, headaches) from approximately 400 female primary cooks in each of three peri‑urban communities in sub-Saharan Africa: Mbalmayo, Cameroon; Obuasi, Ghana; and Eldoret, Kenya. Random effects Poisson regression, adjusted for socioeconomic and health-related covariates, assessed the relationship between primary and secondary cooking fuel type and self-reported health symptoms.

Results

Among 1,147 participants, 10 % (n = 118) exclusively cooked with LPG, 45 % (n = 509) stacked LPG and polluting fuels and 45 % (n = 520) exclusively cooked with polluting fuels. Female cooks stacking LPG and polluting fuels had significantly higher odds of shortness of breath (OR 2.16, 95 %CI:1.04–4.48) compared with those exclusively using LPG. In two communities, headache prevalence was 30 % higher among women stacking LPG with polluting fuels (Mbalmayo:82 %; Eldoret:65 %) compared with those exclusively using LPG (Mbalmayo:53 %; Eldoret:33 %). Women stacking LPG and polluting fuels (OR 2.45, 95 %CI:1.29–4.67) had significantly higher odds of eye irritation than women cooking exclusively with LPG. Second-hand smoke exposure was significantly associated with higher odds of chest tightness (OR 1.92, 95 % CI:1.19–3.11), wheezing (OR 1.76, 95 % CI:1.06–2.91) and cough (OR 1.78, 95 %CI:1.13–2.80).

Conclusions

In peri‑urban sub-Saharan Africa, women exclusively cooking with LPG had lower odds of several health symptoms than those stacking LPG and polluting fuels. Promoting a complete transition to LPG in these communities may likely generate short-term health benefits for primary cooks.

The hydrological dynamics of the Bagmati River downstream from Kathmandu have transformed due to rapid urbanization, impacting regional water projects. Declining open land and groundwater levels have reduced winter base flow and increased summer peak discharge, challenging sustainable energy generation. This study quantifies Land Use and Land Cover (LULC) impact on downstream hydropower. Using LULC data and a calibrated hydrological model in SWAT, it introduces change scenarios, analyzing their influence on river runoff and energy generation. Results reveal varied runoff curve numbers and seasonal discharge due to LULC shifts. Annual mean flow sees a 1.3% increase, while lean flow decreases by 3.45%. Consequently, dry, wet, and total energy generation drops annually by 0.68%, 0.31%, and 0.38%, respectively. The Flow Duration Curve (FDC) notably shifts upwards at its top and downwards at the bottom compared to the base simulation, defining the most sustainable installed capacity. Additionally, the study presents a regression equation based on LULC changes for simplified analysis. It underscores the crucial role of LULC modifications in river runoff, profoundly impacting energy generation and water resource projects' sustainability. Neglecting these changes could severely affect project success.

Agriculture is the second largest contributor (20 %) to total anthropogenic greenhouse gas (GHG) emissions in the world. There is a need to identify energy and carbon efficient cropping systems that reduce GHG emission and improve environmental quality. Using life cycle assessment (LCA), we evaluated the four cropping systems namely fallow – chickpea (F–C); Sesbania – mustard (Ses–M); blackgram – chickpea (B–C); sorghum + cowpea – mustard (S + C–M) cultivated during the 2018–2022 period. The energy use pattern and the input-output relationship were analysed. Three measures were utilized to quantify carbon footprints: CFa, which denotes emissions per unit area; CFb, indicating emissions per kilogram of yield; and CFe, representing emissions per unit of economic output. The result indicates that non-renewable sources of energy (diesel and fertilizer) contributed more than ∼80 % of the total energy consumed in the different cropping systems. The total energy requirement was the highest for S + C–M (16,972 MJ ha^–1), followed by Ses–M (14,365 MJ ha^–1), B–C (11,132 MJ ha^–1) and F–C (8679 MJ ha^–1) cropping systems. The S + C–M cropping system also had the highest energy use efficiency (9.13) followed by F–C (6.03), B–C (5.41) and Ses–M (5.41). The fallow–chickpea cropping system had the lowest values of CF_a, CF_b, and CF_e however, the highest carbon efficiency (10.7) and the carbon sustainability index (9.7) were computed in S + C–M cropping system. Our findings indicate that thoughtfully structured, varied crop systems that integrate legumes and forage crops have the potential to significantly reduce energy consumption and carbon emissions, while sustaining or potentially improving overall productivity within these systems.

The two-stage anaerobic digestion (2st-AD) of sugarcane vinasse is widely studied and well-known for improving the energy recovery potential in sugarcane biorefineries. Maintaining enhanced substrate acidification in a separate (first stage) reactor directly improves the performance of methanogenesis (second stage). However, problems derived from the presence of sulfate (SO₄²⁻) and the subsequent sulfide formation in the second stage are not prevented in conventional 2st-AD systems. In addition, high costs related to reactor alkalinization still represent significant drawbacks in that configuration. The energy recovery potential via methanogenesis was assessed from acidified sugarcane vinasse samples collected from different dark fermentative systems, namely: V1 (subjected to NaOH+NaHCO₃ dosing), V2 (subjected to NaOH dosing) and V3 (subjected to no pH control). Despite the harmfulness of sulfide, the enhanced production of acetate from the incomplete oxidation of organic matter in sulfidogenesis can benefit methanogens. The highest methane yield (296.3 NmL-CH₄ g-COD⁻¹) and global energy recovery potential (354,603 GWh per season) were obtained from the lactate and SO₄²⁻rich vinasse (V2). Nevertheless, from a technological perspective, the methanogenesis of vinasses subjected to the fermentative-sulfidogenic process (V1) provided a higher quality biogas due to a higher calorific power (26.4-27.0 MJ Nm⁻³) and decreased H₂S content in the biogas. Finally, the fermentative-sulfidogenic process as an alkalinizing strategy was demonstrated to be the best economic approach for scaling up the 2st-AD of sugarcane vinasse, overcoming the main economic drawback of this configuration.

The optimization and prediction of thermodynamic parameters including synergistic effects, and kinetic analysis in co-pyrolysis of banana peel (BP) and waste polystyrene (PS) plastic at different heating rates using ANN and AIC models has been performed. Thermogravimetric analysis was performed to determine the initial, maximum, and final degradation temperatures. The synergistic effect was studied using additive formula to determine the theoretical thermal behavior and compared with experimental TGA data. Kinetic parameters were determined by using the advanced isoconversional (AIC) model for estimation of activation energy (E_α), Criado master plot for reaction mechanism (f(α)), and compensation method for frequency factor (A_α). The analysis showed that the average activation energy values were 182.5, 140.6, and 161.8 kJ mol⁻¹ for PS, BP, and PS+BP, respectively. It also clearly shows positive synergy in co-pyrolysis of PS and BP by reducing 11.3 % activation energy compared to that of PS alone. The frequency factor was found to be 1.0 × 10¹⁴, 1.0 × 10¹⁵, and 1.0 × 10²³ s⁻¹ for PS, BP, and PS+BP, respectively. The reaction mechanism was identified as R3, D4, and D4+R3 for PS, BP, and PS+BP, respectively. Further, the obtained kinetic parameters were used to determine the thermodynamic parameters such as enthalpy (ΔH), Gibbs energy (ΔG), and Entropy (ΔS). Finally, ANN was designed to address the co-pyrolysis behavior subjected to various heating rates. Subsequently, the trained ANN model (5 × 4×4 × 4) was employed to forecast thermal degradation behavior. Impressively, the model yielded highly accurate results with a correlation coefficient R² > 0.998 in each case. The optimized model was further used to predict TGA data and activation energy for unknown mixtures of PS and BP. The suggested ANN model showed a great advantage in optimizing to avoid extensive experiments at various heating rates to achieve the goal.

The rise in the population and rapid industrialization has resulted in a rise in the global energy consumption. In order to minimize the load on the conventional energy sources, various studies are being conducted for the production of biofuels by hydrothermal operations. Unlike conventional processes of biofuel production, wet biomass can be directly utilised without drying in turn reducing the energy consumption. Feedstocks such as agricultural residue, forest residue, energy crops, algae, sludge, litter and food waste can be utilised for the production of biofuels. The operation intensities (temperature and pressure) can be varied from pressurized hot water to supercritical water. Hydrothermal operations depending on the operating parameters are further subcategorised into four types namely wet torrefaction (WT), hydrothermal carbonization (HTC), hydrothermal liquefaction (HTL) and hydrothermal gasification (HTG). Even though the operating conditions of wet torrefaction and hydrothermal carbonization lie in similar categories, the difference is clearly visible in the level of carbonization. Due to the wide range of operating temperature and pressure, mainly three different products are produced through hydrothermal operations. The temperature range for wet torrefaction can be limited between 150 and 220 °C, whereas the HTC process can be between 200 and 260 °C. At higher temperatures (260 – 370 °C) in hydrothermal liquefaction (HTL), increased isomerization, depolymerization and repolymerization of organic compounds within the biomass occurred, causing liquid product (bio-oil) to be formed as the major product. Hydrothermal gasification can be further subcategorised into three types: namely aqueous phase refining, near critical water gasification and supercritical water gasification (SCWG). This paper has reviewed different hydrothermal operations based on biofuel production from different biomass.

The water-energy-food (WEF) nexus is an interdisciplinary approach to address the transdisciplinary issues of developing a specific area with limited resources. We studied the potential of implementing the WEF model in the Rabia region located at Matrouh Governorate in Egypt on the Mediterranean Sea, to introduce sustainable management solutions for the limited resources in this area. The Rabia community lacks any source of water services and is not connected to the electric grid. It depends on existing wells that harvest rainwater for potable and non-potable purposes. The introduced WEF nexus scheme is based on the available resources in Rabia region to produce the required water for drinking, cultivation, and other purposes in addition to maximizing the productivity of water. It also provided renewable energy resources and food security in the area. The proposal also empowers women and provides job opportunities for the community, in addition to reducing carbon emissions to contribute to the efforts fighting climate change. This work will benefit policymakers, investors, and the local community to take tangible actions toward sustainable development in the region and other similar communities in arid coastal regions. The proposed scheme will save about 52 % of the required electricity and 54 % of the carbon emissions, through the use of renewable energy sources. It produces 2,096 t/yr of crops. It supports the achievement of many sustainable development goals and will promote the achievement of Egypt's National Vision 2030.