• Energy Research
• 2021-2025close
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The Nigerian government is committed to sustaining rice production to meet national demand. Nevertheless, political tension and climate-induced stressors remain crucial constraints in achieving policy targets. This study examines whether climate change and political instability significantly threaten rice production in Nigeria. First, we employed nonparametric methods to estimate the country's rainfall and temperature trends between 1980Q1 and 2015Q4. Second, we employed the autoregressive distributed lag (ARDL) technique to examine the effects of climate change and political instability on rice production. The results show that while temperature has an increasing pattern, rainfall exhibits no significant trend. The findings from the ARDL estimate reveal that rice production responds negatively to temperature changes but is less sensitive to changes in rainfall. In addition, political instability adversely affects rice production in Nigeria. We argue that Nigeria's slow growth in rice production can be traced back to the impact of climate change and political tension in rice farming areas. As a result, reducing the overall degree of conflict to ensure political stability is critical to boosting the country's self-sufficiency in rice production. We also recommend that farmers be supported and trained to adopt improved rice varieties less prone to extreme climate events while supporting them with irrigation facilities to facilitate rice production.

Humidification dehumidification water desalination system using two cycles of air flow (open and closed-air cycles).

Response of aquatic organisms to eutrophication have been well reported, while less studies are available for the recovery of eutrophic lakes following a reduction in the external loading, especially for systems where nitrogen is reduced but the phosphorus concentration is maintained high due to internal loading. Diatoms are nitrate (NO3-N) opportunists but can also use ammonium (NH4-N). They may, therefore, be more sensitive to nitrogen reduction than other algae that typically prefer NH4-N. We document the variations of nutrients and diatoms in subtropical, eutrophic Lake Taihu over 28 yr during which a reduction of the external loading resulted from lake management. According to the results of change point analysis, data on environmental variables were divided into two periods (P1: 1992-2006; P2: 2007-2019) with two different seasons (WS: Winter-Spring; SA: Summer-Autumn), respectively. Compared with P1-WS, the concentration of NH4-N decreased significantly whereas NO3-N showed no significant change in P2-WS. In contrast, NH4-N concentrations were low and showed no significant changes in P1-SA and P2-SA and NO3-N decreased significantly in the latter period. Accordingly, NO3-N: NH4-N mass ratios in P1-SA and P2-WS were all significantly higher than those in P2-SA and P1-WS, respectively. The biomass of WS diatom increased significantly and the timing of the peak biomass shifted from P1-SA to P2-WS since 2007. The SEM analysis showed that NO3-N was retained as a statistically significant predictor for diatom biomass in P1-SA and significant effects of windspeed, zooplankton and NH4-N on diatom biomass in P2-WS. Windspeed and zooplankton have further changed the biomass of diatoms in the case of declining inorganic nitrogen. We conclude that the magnitude of vernal suppression or stimulation of diatom assemblages has increased, concomitant with the variations of NH4-N and NO3-N: NH4-N mass ratios. Diatoms response to NH4-N or NO3-N is apparently changing in response to water temperature in this eutrophic shallow lake. Thus, parallel reductions in external nitrogen loading, along with variations in dominant inorganic nitrogen, will stimulate the growth of diatom and therefore increase the total biomass of phytoplankton in still high internal phosphorus loading, which is should be regarded as a good sign of restoration measures.

While there is a consensus on the multifaceted advantages of wind farms, only a handful of developing countries harness it to the fullest potential. Among the various factors that contributed to the low development of wind farms in those countries, the dearth of methods for identifying a suitable site is the leading one. Studies conducted elsewhere on wind farm industry identifies criteria such as slope, wind speed, land use/land cover, geology, distance from electric transmission grids, roads, and settlements. However, the relative magnitude of each factor to the optimum location of the wind farm is inadequately examined. This study focuses on the combined use of geographic information systems (GIS) and spatial multi-criteria decision analysis (MCDA) for selecting the most appropriate sites for wind-farm development. Using a pairwise comparison method of the analytical hierarchical process, we computed the relative importance and weight of parameters affecting wind farm sites in a weighted overlay technique. Based on the analysis of pertinent data collected from Bahir Dar City and its surroundings, northwestern Ethiopia, we categorized the study area into five suitability classes ranging from extremely suitable to not suitable. Our result, revealed a spatial pattern of the potential sites suitable for wind farm investments that are economical, environmentally sound, and aesthetically amenable. We recommend replicating the method developed in this study in other areas of developing countries where transitioning to renewable energy sources through windfarm development is sought.

Abstract Pelton turbine, with its unique advantages in high mountainous region especially in the southwest of China, has received more and more attention. This paper focuses on the erosion influence to the hydraulic characteristics by Euler particle tracking model. Two-phase numerical simulation results are compared with the model experiment results and are proved to be accurate. Solid particle is then added in the flow and three-phase flow is solved. Particle parameters (silt particle size, concentration) were considered to investigate the mechanism of silt erosion on Pelton turbine distribution system including distributor, bifurcation tubes, and nozzle structure. It proves that erosion destroys the vortex structure in bifurcation tubes. As the particle's diameter increases, discharge in different bifurcations appear more uniform. With the particle flow, a strong collision phenomenon appears at nozzle seat. As the particle's diameter increases, the erosion strengthens accordingly. This study reveals that the particle influence induces erosion which is important to be considered during the design and operating procedures in the whole life of Pelton turbine.

The rapidly evolving global warming is triggering all levels of actions to reduce industrial carbon emissions, while capturing carbon dioxide of industrial origin via microalgae has attracted increasing attention. This article attempted to offer preliminary analysis on the carbon capture potential of microalgal cultivation. It was shown that the energy consumption-associated with operation and nutrient input could significantly contribute to indirect carbon emissions, making the microalgal capture of carbon dioxide much less effective. In fact, the current microalgae processes may not be environmentally sustainable and economically viable in the scenario where the carbon footprints of both upstream and downstream processing are considered. To address these challenging issues, renewable energy (e.g., solar energy) and cheap nutrient source (e.g., municipal wastewater) should be explored to cut off the indirect carbon emissions of microalgae cultivation, meanwhile produced microalgae, without further processing, should be ideally used as biofertilizer or aquafeeds for realizing complete nutrients recycling.

AbstractIn this study, a novel solar tower-based gas turbine-driven multi-generation plant is proposed and analyzed in detail with energy, exergy, economic, and environmental impact analysis. A multiobjective optimization is performed by incorporating all performance indicators simultaneously. The proposed plant consists of an intercooling-regenerative-reheat solarized gas turbine cycle as the primary power cycle of a multi-generation plant for the first time. Two organic Rankine cycles are used to utilize waste heat of intercooling section and exhaust of gas turbine. To produce the multi-generation products of power, cooling, industrial process heating, fresh water, floor heating, green hydrogen, domestic hot water, hot air for food drying, and greenhouse heating, power cycles are integrated with a multi-effect desalination, a double-effect absorption refrigeration cycle, an electrolyzer, a drying hot air unit, a greenhouse heater, and an industrial process heater. A rigorous parametric analysis is performed to reveal the effects of variations of decision variables on the plant performance. At the optimum conditions, energy efficiency, exergy efficiency, average unit product exergy cost, and emission savings values are determined as 57.23%, 40.7%, 0.08315 $/kWh, and 948.7 kg CO2/h, respectively. Moreover, proposed plant can produce 1962 kW power and 3.353 kg/h hydrogen in addition to other utilities with a system cost rate of 0.05134 $/s and 3226 kW exergy destruction rate.

Abstract Anaerobic digestion (AD) technology has piqued scientists’ interest in light of the growing demand for renewable energy and environmental preservation. This paper discusses the analysis of national biogas producing capacity, energy demand, and methods for meeting that demand. Also, public health and environmental issue, biogas technology and their utilization, current national scenario, and future in the biogas field have been discussed. The Government of India (GOI) has been providing subsidies or financial support through various programs. They support the rural area for generating biogas and also announced the Sustainable Alternative Towards Affordable Transportation (SATAT) initiative for the generation of compressed biogas (CBG) for the installation of 5000 plants up to 2023-24. These plants are expected to produce 15 million metric tonnes (MMT) of CBG per annum, which is about 40% of the current compressed natural gas (CNG) consumption of 44 MMT per annum in the region.

Exorbitant substrates for Schizochytrium culture result in the high cost of docosahexaenoic acid (DHA) production. In order to develop a feasible approach that is expected to reduce DHA production cost, Schizochytrium sp. S31 cultivation with a mixture of saline wastewater (SWW) and tofu whey wastewater (TWW) was investigated in this study. Using glucose as the carbon source, the maximum biomass and DHA yield in cultures using mixed wastewater containing 5% SWW reached 19.08 and 2.66 g/L, respectively, which were 2.29 and 2.66 times higher than those of cultures using control medium. Moreover, a good wastewater treatment performance was achieved as approximately 60% of the COD, TN, and TP were reduced in the cultures using mixed wastewater with a SWW ratio of 5%. The mixed wastewater presented better performance on DHA production than control medium using all tested carbon sources including glucose, fructose, and pure and crude glycerol. The components of control medium can be completely replaced by the mixed wastewater and crude glycerol. It is expected to effectively decrease the medium cost for DHA production and reduce the environmental risk of food processing wastewater.