Changes In Solar Radiation Research Articles

Synthesis and characterization of efficient photocatalyst from seaweed extract under solar irradiation

Silver-doped zinc oxide nanoparticles (NPs) were synthesized employing a facile hydrothermal method supported by the seaweed Turbinaria ornata (TO). TO extract was used as a capping agent. The prepared NPs were accounted for using instrumentational analysis such as FE-SEM, EDS, XRD, FTIR, and UV-Vis. Their characteristic study showed an average size of 26 nm with 81% crystallinity with X-ray Diffraction and the band-gap value as 3.25 eV. The biosynthesized doped particle exhibited rod-shaped morphology for better efficiency in dye degradation of Methylene Blue (MB) dye. They were also tested for adsorption kinetics and photocatalytic degradation of MB using sunlight. The efficiency in degrading the MB dye proclaimed a remarkable change in solar irradiation of about 90% reduction to visible light, which leads to the betterment in solar degradation of dye pollutants at a minimal cost.

Build and Implement Radiation Control using IoT in Parabolic Trough Solar Collector (PTSC)

Connecting the devices to the internet based on the internet of things IoT increases the capability of monitoring and measuring, and controlling essential variables. In this study, the radiation intensity was controlled via the internet of things IoT for PTSC to study the collector's behavior. The light control circuit was designed, built, and implemented. The circuit mainly consists of a power supply, Arduino, relay, and potentiometer. Radiation was successfully monitored using a sensor and displayed through a smartphone via Wi-Fi, and the intensity of radiation light controls the PCM status. A data logging system was applied using a micro SD in a smartphone card and Arduino Node-MCU as a microcontroller. The experimental results show the relationship between solar radiation and resistance change. Inversely, the maximum radiation found from this work was 780 W/m2 with 74 k Ω resistance, and the minimum radiation was 300 W/m2 with 170 k Ω resistance. The output power changes directly through solar radiation, which means the power output with maximum solar radiation will be 3018 W. Using IoT Technology reduces efforts of long-time monitoring during the experiment (many hours).

A new tuning rule for stabilized integrator controller to enhance the indirect control of incremental conductance MPPT algorithm: Simulation and practical implementation

The Incremental Conductance (IncCond) algorithm based on direct control mode is one of the highest Maximum Power Point Tracking (MPPT) algorithms ensuring multiple performances compared to some other classical methods. Unfortunately, these performances can deteriorate, especially in the case of sudden changes in weather conditions and load variation., Preventing these drawbacks will form the basis of a new IncCond-MPPT scheme based on indirect control mode in which a smooth electrical power response generated by photovoltaic (PV) panels is well ensured, regardless of quick changes in solar irradiance, absolute temperature and load variation. The proposed MPPT approach uses two stages of control. The first one is used to provide the reference PV-module voltage. The second control loop is formulated as a transfer function that is then controlled using an appropriate Integral controller. Its integral gain is well tuned by applying the Routh’s stability criterion on the characteristic equation of the obtained closed loop transfer function. This allows providing the proposed new guideline, which represents the main contribution of this paper. The proposed IncCond-MPPT scheme is compared with the standard one in terms of MPP tracking accuracy and electrical power ratio, which exceeds 97 %, where quick changes of weather conditions and load variations are considered.

Experimental evaluation of type‐2 fuzzy logic controller adapted to real environmental conditions for maximum power point tracking of solar energy systems

AbstractThe conventional angle of incremental conductance (AIC) method fails to track the maximum power point (MPP) when a rapid change in solar irradiation and/or panel temperature appears because it cannot distinguish between rapid changes in photovoltaic (PV) current and voltage under real environmental conditions. The present study describes setbacks of the conventional AIC method and proposes an effective approach based on the combination of AIC and type‐2 fuzzy. The proposed approach offers a significant advantage in terms of maximum power transfer to the load under long‐term weather patterns under which broken clouds appear frequently during a 40‐m testing period. The proposed approach is installed on 250 W module of a 10 kWp real PV plant in Kahramanmaras Sutcu Imam University. Later, its performance is validated by dSPACE1104 controller card operating in real time with MATLAB/Simulink tools using daily measured data. The experimental results obtained from the laboratory setup based on dSPACE1104 controller card demonstrate the facility and feasibility of the proposed approach for real PV plant with boost power converter and load.

Influence of long-term changes in solar irradiance forcing on the Southern Annular Mode

Abstract. The Southern Annular Mode (SAM) is the leading mode of climate variability in the extratropical Southern Hemisphere, with major regional climate impacts. Observations, reconstructions, and historical climate simulations all show positive trends in the SAM since the 1960s; however, earlier trends in palaeoclimate SAM reconstructions cannot be reconciled with last millennium simulations. There are also large differences in the magnitude of solar irradiance change between various solar reconstructions, although most last millennium climate simulations have relied on a low-amplitude solar-forcing scenario. Here we investigate the sensitivity of the SAM to solar irradiance variations using simulations with a range of constant solar-forcing values and last millennium transient simulations with varying amplitude solar-forcing scenarios. We find the mean SAM state can be significantly altered by solar irradiance changes and that transient last millennium simulations using a high-amplitude solar scenario have an improved and significant agreement with proxy-based SAM reconstructions. Our findings suggest that the effects of solar forcing on high-latitude climate may not be adequately incorporated in most last millennium simulations due to solar irradiance changes that are too small and/or the absence of interactive atmospheric chemistry in the global climate models used for these palaeoclimate simulations.

Analysis of the All-Year Operation of the Solar Chimney in Polish Climatic Conditions

This work presents an analysis of the all-year operation of the solar chimney. The analyzed system consists of a rectangular solar collector located on the southern side of the solar chimney. The surface of the solar collector is 30 m2, while the chimney is 50 m in height. Hourly changes in solar radiation were taken into account in the calculations. The simulation was made for the climatic conditions in Katowice, Poland. This study takes into account the most important parameters of the power plant, such as air temperature, air velocity and power of the installation throughout the year of the power plant’s operation. The cumulative amount of electricity that is generated in each month of the year is shown. The analyzed solar power plant produces the largest amount of electricity in the second quarter of the year and the lowest in the fourth quarter, with the maximum amount of energy produced in May and the minimum in December.

A Novel PV Maximum Power Point Tracking Based on Solar Irradiance and Circuit Parameters Estimation

This research paper presents a novel maximum power point taking (MPPT) algorithm. The algorithm uses an adaptive calculation block to estimate the solar irradiance and the PV I–V curve circuit parameters based on the PV panel’s measured output current and voltage. In the proposed algorithm, the output power does not oscillate around the maximum power point (MPP) compared to conventional MPPT methods. Moreover, the proposed algorithm does not require expensive solar irradiance sensors compared with trackers that depend on measured solar irradiance. In addition, the proposed MPPT can handle the fast variation in solar irradiance. The PV panel nonlinear I–V curve was modeled using a single-diode PV. The algorithm with the adaptive block was tested separately to verify the ability of the system to estimate the solar irradiance and the circuit parameters. The solar system was then simulated using MATLAB/Simulink to evaluate the robustness of the proposed method under steady-state and during sudden changes in solar irradiance and load. The proposed solar system reaches the steady-state in 8 ms after a step-change in the solar irradiance. In the worst-case scenario, the proposed system achieves a relative error of around 2.64% in estimating the solar irradiance at 600 W/m2 with an efficiency of 99.3%.

Observation‐Based Evaluation of Local Climate Effect of Terrestrial Vegetation in Temperate Zones

AbstractTerrestrial vegetation modulates the land‐atmosphere dynamics and is one of the fundamental forces for climatic variability. The vegetation feedback may enhance or offset a portion of ongoing global warming. However, it is challenging to disentangle the role of vegetation from the effect of other drivers, primarily due to lacking suitable reference without vegetation. Fortunately, China has recorded the land surface temperature (LST) on bare land in 2400s weather stations, providing a deal bare‐land reference. Here, we used satellite measurements of the vegetation's canopy temperature, contrasted with the surface temperature of bare land, to quantify the vegetation's effect on LST. Results show that vegetation has a cooling effect during daytime and a warming effect at night, and the magnitude of the former is significantly higher than that of the latter. Consequently, vegetation has a net cooling effect and reduces LST up to 2.18°C in China. Spatially, the cooling effect of vegetation decreases by 0.25°C for a unit increase of latitude. Based on land surface energy balance, the spatial pattern of vegetation's net effect is mainly driven by vegetation‐induced evapotranspiration and albedo. As latitude increases, the decrease of vegetation density significantly reduces the evapotranspiration‐induced cooling effect while having no distinct impact on the albedo‐induced warming effect. As a result, the net cooling effect of vegetation has an evident latitudinal gradient and a clear seasonal contrast. Additionally, the vegetation's effect on LST is sensitive to solar radiation and snow cover changes.

Research on the Internal Flow Characteristics of Pump Turbines for Smoothing the Output Fluctuation of the Wind–Photovoltaic Complementary System

Wind and photovoltaic (PV) power generation and other distributed energy sources are developing rapidly. But due to the influence of the environment and climate, the output is very unstable, which affects the power quality and power system stability. Pumped hydroelectric energy storage (PHES) systems are suitable as peaking power sources for wind and photovoltaic (Wind–PV) complementary systems because of their fast start–stop and long life. The mathematical models and operational characteristics of the three subsystems in the wind–PV–PHES complementary system are analyzed to improve the generation efficiency and access capacity of wind and PV power. The peaking characteristics of the PHES system are used to balance the maximum benefit and minimum output fluctuation of the wind–PV complementary system. The stable operation of the pump turbine is an important guarantee for the smooth output of the wind–PV complementary system. Three operating points are selected from the net load curve and converted to the pump turbine model parameters. The internal flow characteristics and laws of the pump turbine under different guide vane opening conditions are summarized through the analysis of the computational fluid dynamics (CFD) numerical simulation post-processing results. The study shows that the output of wind and PV power generation varies with the changes in wind speed and solar radiation, respectively. The output of the wind–PV complementary system still has large fluctuations, and the PHES system can effectively suppress the power fluctuation of the wind–PV complementary system and reduce the abandoned wind and light rate. CFD technology can accurately and efficiently characterize the internal flow characteristics of the pump turbine, which provides a basis for the design, optimization, and transformation of the pump turbine.

Dust accumulation effect of glazing cover inner surface on the performance of transpired solar air collector

Relative to the easier removal of accumulated dust on the outside of solar devices, it's very difficult to clean up the internal dust particles. So, from the aspect of ensuring the long-term high-performance operation of transpired solar air collector, the paper investigates the tilt angle effects on the dust accumulation amount of glazing cover inner surface and associated reduction in collector performance. In process, various forces causing the dust particles move to the inner surface and collide with them and then deposit, are thoroughly analyzed. To estimate the heat collected loss induced by dust, an empirical relationship predicting the light transmittance reduction has been explored, valid for relatively small dust accumulation amount. The results indicate that mainly under the force of gravity, the dust deposition density on the inner surface increases with the tilt angle. However, in view of the difference of solar irradiance in five tilt angles at the same time, it is not that the higher the dust deposition density, the lower the temperature rise from collector inlet to outlet. Hence, the tilt angle should be determined based on the comprehensive evaluation of the resulting changes of solar irradiance and dust accumulation amount, combined with local meteorological conditions.

Frequency regulation of hybrid multi-area power system using wild horse optimizer based new combined Fuzzy Fractional-Order PI and TID controllers

The increasing penetration of renewable energy sources (RES) into modern power systems may reflect the problem of frequency stabilization. Therefore, this paper proposes a new combined Fuzzy Fractional-Order Proportional-Integral (FOPI) and Tilt-Integral-Derivative (TID) controller to improve the frequency response of a hybrid power system. The proposed controller combines the advantages of intelligent Fuzzy FOPI and conventional TID controllers, resulting in more effective and robust load frequency control. In this study, the parameters of the proposed Fuzzy FOPI + TID combination are optimized using a novel metaheuristic algorithm, namely Wild Horse Optimizer (WHO). The case study system is a two-area conventional power system integrated with different RES including photovoltaic (PV) and wind generation as well as distributed electric vehicles (EVs) between the two areas. The effectiveness of the proposed controller is tested under various scenarios such as step load perturbation, random load variation, wind speed fluctuation, solar irradiance change and sensitivity analysis. In addition, the disturbance of wave energy oscillation is applied in Area 2 to evaluate the robustness of the proposed controller. For each scenario, the proposed Fuzzy FOPI + TID controller is compared with the conventional PID, single TID, and individual Fuzzy FOPI controllers using the proposed WHO algorithm and other optimization algorithms presented in the previous literature. The results show that the proposed FOPI + TID controller is superior to other controllers in terms of integral square error, peak overshoot, maximum undershoot and settling time for all scenarios. Furthermore, the presence of EVs helps in improving the frequency and tie-line power deviations. Finally, the time domain simulations are implemented using Matlab/Simulink.

Perceptions of Pastoralists about Climate Change in Ethiopia: A Case Study of Saba Boru District

This study was conducted in the Saba Boru district of the Guji zone in Ethiopia's Oromia regional state. A long-term alteration in a nation's or region's climatic tendencies is referred to as climate change. Agriculture accounts for roughly 47 percent of Ethiopia's GDP, and more than 85 million people rely on agriculture for a living, either directly or indirectly. This study examined local pastoralists' perceptions of climate change and related problems and is based on primary data collected from 821 households of 12 kebeles of the Saba Boru district. The collected data have been analyzed via descriptive and inferential statistics evaluate the results. There is increased annual temperature from 20.6 °C to 21.28 °C, large variance in annual rainfall from 758.23 to 2.32 mm, and higher change in annual solar radiation from -99 °C to 18.33 °C during 1981 to 2019 are the evidence of climate change. More than 81 percent of respondents agreed that higher rainfall and changes in rainfall patterns were the shreds of evidence of climate change, while 78.1 percent agreed that greater drought was a sign of climate change. Although 79.3 percent of respondents agreed to an increase in temperature and high sunlight intensity as observed evidence of climate change, 15.2 percent disagreed. Similarly, 41.3 percent of respondents disagreed on the low fertility of most soils as observed signals of climate change, while 53.4 percent agreed. The study demonstrates that respondents in the communities examined are aware of climate change, but with variable levels of agreement.

Impact of eastern and central Pacific El Niño on lower tropospheric ozone in China

Abstract. Tropospheric ozone, as a critical atmospheric component, plays an important role in influencing radiation equilibrium and ecological health. It is affected not only by anthropogenic activities but also by natural climate variabilities. Here we examine the tropospheric ozone changes in China associated with the eastern Pacific (EP) and central Pacific (CP) El Niño using satellite observations from 2007 to 2017 and GEOS-Chem simulations from 1980 to 2017. GEOS-Chem reasonably reproduced the satellite-retrieved lower tropospheric ozone (LTO) changes despite a slight underestimation. In general, both types of El Niño exert negative impacts on LTO concentration in China, except for southeastern China during the pre-CP El Niño autumn and post-EP El Niño summer. Ozone budget analysis further reveals that for both events, LTO changes are dominated by the transport processes controlled by circulation patterns and the chemical processes influenced by local meteorological anomalies associated with El Niño, especially the changes in solar radiation and relative humidity. The differences between EP- and CP-induced LTO changes mostly lie in southern China. The different strengths, positions, and duration of the western North Pacific anomalous anticyclone induced by tropical warming are likely responsible for the different EP and CP LTO changes. During the post-EP El Niño summer, the Indian Ocean capacitor effect also plays an important role in mediating LTO changes over southern China.

A Simulation Study on the Variation of Thermospheric O/N2 With Solar Activity

AbstractThe ratio of number density of atomic oxygen (O) to that of molecular nitrogen (N2) in the thermosphere (O/N2) on the constant pressure surface, which has complex temporal and spatial characteristics, is widely regarded as an important parameter connecting the terrestrial thermosphere and daytime ionosphere. Previous studies demonstrated that the thermospheric O/N2 increases with increasing solar activity, and the changes in O/N2 with solar activity show significant difference between winter and summer hemispheres. However, the root causes, which are responsible for the solar activity variation of O/N2, are not fully understood. In this study, the contributions of various physical and chemical processes on the response of O/N2 to the solar radiation change were quantitatively investigated through a series of controlled simulations from the Thermosphere Ionosphere Electrodynamics General Circulation Model. The simulation results suggested that the chemical processes lead to the increase of thermospheric O/N2 over the globe with increasing solar activity. The increase of O/N2 with solar activity is dominated by the enrichment of O abundance and the loss of N2 abundance in the lower and upper thermosphere, respectively. Moreover, the simulation results suggested that the stronger hemispheric asymmetry is attributed to the stronger thermospheric circulation, which changes the vertical advection of O/N2 through both direct and indirect effects.

Spatial and temporal variations of maize and wheat yield gaps and their relationships with climate in China

With the growth in population over the past decades, China’s food demand has been increasing. However, crops are facing greater water stress with the rising temperature and increasing drought in future. Therefore, identifying potential crop yield and its driving factors is necessary to ensure continued food production. In the present study, we estimated the potential yields of maize and wheat in China, with and without water limits, from 1985 to 2015 using a simple generic crop model (SIMPLE). We then investigated how climate factors (temperature, precipitation, and solar radiation) drove the spatial and temporal variation of yield gaps (quantified as the difference between potential yields with and without water limits). We found an increasing trend in the water limited yield gap of maize in northern China (3.9 ± 4.3 kg ha-1 yr-2) and wheat in central China (2.6 ± 2.4 kg ha-1 yr-2). The temporal trends of maize and wheat yield gaps in China were mainly related to precipitation and temperature. However, the spatial variation in maize yield gap trends was mainly related to the variations in precipitation, whereas for wheat it was attributed to changes in temperature or solar radiation. Upgrading irrigation infrastructure and management techniques or spatially adjusting crop types could help closing the yield gap of wheat in some zones.

Energy, exergy, economic and emission saving analysis and multiobjective optimization of a new multi-generation system based on a solar tower with triple combined power cycle

In the present work, an original solar tower based multi-generation system with triple combined power cycle is proposed and investigated in detail. The novel system deploys a solar tower-based Brayton cycle, a single-stage regenerative organic Rankine cycle and a Goswami cycle. A multi-effect desalination, an electrolyzer and a LiBr absorption cooling system are coupled to the triple combined power cycle for the purpose of power, heating, fresh water, green hydrogen, refrigeration, space cooling and hot water production. Thermodynamic, economic and emission saving viewpoints are examined together with parametric investigation. Effect of variation of power size of the electrolyzer on the overall system performance and effect of change in solar irradiation are also analyzed. Multiobjective optimization is performed considering thermodynamic and economic objectives simultaneously. At the optimum conditions, proposed system has 51.99% and 37.99% energy and exergy efficiency values, respectively, and achieves 513.8 kg CO2/h emission savings and 0.0352 $/kWh unit product profit. Total revenue rate and total cost rate are calculated as 168.2 $/h and 92.3 $/h, respectively. Discounted payback period calculation shows that the system compensates itself economically in 4.79 years.

Variations and Environmental Controls of Primary Productivity in the Amundsen Sea

The Amundsen Sea is one of the regions with the highest primary productivity in the Antarctic. To better understand the role of the Southern Ocean in the global carbon cycle and in climate regulation, a better understanding of the variations and environmental controls of primary productivity is needed. Using cluster analysis, the Amundsen Sea was divided into nine bioregions. The biophysical differences among bioregions enhanced confidence to identify priorities and regions to study the temporal and spatial variations in primary production. Four nearshore bioregions with high net primary productivity or rapidly increasing rates were selected to analyze temporal and spatial variations in primary productivity in the Amundsen Sea. Due to changes in net solar radiation and sea ice, primary production had significant seasonal variation in these four bioregions. The phenology had changed at two bioregions (6 and 7), which has the third and fourth highest primary production, due to changes in the dissolved iron. Annual primary production showed increasing trends in these four bioregions, and it was significant at three bioregions. The variation in primary production in the bioregion (9), which has the highest primary production, was mainly affected by variations in sea surface temperatures. In the bioregion (8), which has the second-highest primary production, the primary production was significantly positively correlated with sea surface temperature and significantly negatively correlated with sea ice thickness. The long-term changes of primary productivity in bioregions 6 and 7 were thought to be related to changes in the dissolved iron, and dissolved iron was the limiting factor in these two bioregions. Bioregionalization not only disentangles multiple factors that control the spatial differences, but also disentangles limiting factors that affect the phenology, decadal and long-term changes in primary productivity.

The climate change perspective of photovoltaic power potential in Brazil

Photovoltaic power potential (PPV) is part of the strategies in Brazil to satisfy the population's energy demand and contribute to reduction of global warming in the climate change context. This study assesses climate change's impact on PPV using a set of 47 state of the art Earth System Models from CMIP6 under two climate change (SSP2-4.5 and SSP5-8.5) scenarios. Changes in solar radiation, temperature and PPV are calculated for the near-term (2021–2050) and end-century (2071–2100) future, concerning the historical period (1981–2010). For the future, the sign of climate change is consistent in both scenarios, but with more intense magnitudes in the SSP5-8.5 for the end-century, and indicate a brightening in North region and warming in the whole country. For the near-term future, PPV projects the maximum increases (≈3%) in the North under both scenarios. The most notable decreases in PPV are noticed by the end-century (−5%) over the country, except for the extreme north. The sensitivity to the increase in temperature of current PPV systems' technology would not allow increases in the yield of PPV, canceling the positive effect of the brightening.

Transient power polarity based fault detection in DC microgrid with localized backup scheme

Increasing energy demand and the proliferation of renewable energy sources inflicts new challenges to the conventional protection and control methodologies. Hence, a high speed, precise and reliable protection scheme is required for modern power system. In this paper, a novel protection scheme based on the characteristics of transient power is proposed for DC microgrid in grid-connected and islanded mode of operation. The proposed scheme incorporates primary as well as localized backup protection scheme. The primary protection utilizes the polarity of transient power determined at both ends of the cable under different fault conditions to discriminate between internal and external faults. The primary protection scheme doesn’t require high speed communication and synchronous data. However, in case of a communication link failure, primary protection may also fail to detect a fault; hence a localized backup protection scheme based on the change in average transient power observed at either end of the cable under different operating conditions is used to isolate the faulty section. The effectiveness of the proposed scheme is validated by simulating different fault conditions such as internal and external faults along with system transients such as AC side faults, noisy environment, load variation, DG outage and generation uncertainties due to change in solar irradiance and wind speed. Further, the proposed scheme is also validated on a scaled-down hardware setup in the laboratory, which illustrates the effectiveness and robustness of the proposed protection scheme.

A novel fault detection and classification scheme for DC microgrid based on transient reactor voltage with localized back-up scheme

Integration of renewable energy sources in distribution system inflicts new challenges to the conventional protection scheme by substantially changing the amplitude and direction of fault current. In this paper, a novel protection scheme for DC microgrid based on the characteristics of reactor voltage during transient operation in both grid-connected and islanded mode of operation is proposed. The proposed protection scheme incorporates both primary as well as localized back-up protection scheme. In order to detect and classify faults, primary protection scheme utilizes the polarity of the transient reactor voltage at both ends of the cable under different operating conditions. As the primary protection uses the polarity of reactor voltage at both ends, thus the proposed scheme doesn’t require high speed communication and synchronous data. In case of communication failure, localized back-up protection scheme based on the change in reactor voltage at one end of the cable is used to identify the faulty section. The efficacy of the proposed scheme is verified against various internal and external faults along with system transients such as AC side faults, load variation, DG outage, noisy environment and generation uncertainties due to change in solar irradiance and wind speed. Finally, a scaled down hardware setup is used to validate the proposed protection scheme, which further illustrates the feasibility and reliability of the proposed protection scheme.