Fluctuations In Solar Radiation Research Articles

Analysis of the feasibility of Combined Concentrating Solar Power With Multi Effect Desalination for Algerian Coast

The combined solar tower concentrating power plant (CSP) with multi effect distillation (MED) unit was studied in this work. Five sites in the coastal zones of ALGERIA are examined based on dynamic modelling, which was performed by TRNSYS 17 software, in order to investigate the feasibility of this type, an economic analysis was done. The MED unit is incorporated to replace the condenser in the power block system (cogeneration by exploiting the heat ejected by the condensation of the steam in the power block). The Technico-economic results obtained show that the cogeneration in the concentrating solar tower power plant can produce the electricity and the fresh water for the different zones tested in good proportion. In the proposed study, the produced fresh water quality with MED unit is not affected with the solar radiation intermittence and fluctuation in partial load, in which, only the quantity of produced water varied according to the steam flow entered in the MED unit. The obtained results for the examined sites show that the Algerian coast is suitable for the technology of CSP-MED.

Quantification of the Solar Radiative Regime Variability Based on the Clearness Index

Abstract The fluctuation of solar radiation at ground level represents a challenge in modeling the time series of solar irradiance. A procedure for the quantification of the instability of the solar radiative regime is reported. This procedure is based on the clearness index, as the ratio of the horizontal solar irradiance measured at ground level and the estimated one at extraterrestrial level. New quantities for classifying the days from the radiative stability point of view are being introduced. A procedure for classifying days according to their stability regime as stable, variable and unstable is presented.

Overlapping Leaves Covering Flowers in the Alpine Species Eriophyton wallichii (Lamiaceae): Key Driving Factors and Their Potential Impact on Pollination

Extrafloral structures are supposed to have evolved to protect flowers from harsh physical environments but might have effects on pollination. Overlapping leaves cover flowers in Eriophyton wallichii, an alpine perennial endemic to the Himalaya-Hengduan Mountains. In previous study, it has showed that these extrafloral leaves can protect interior flowers from temperature fluctuations caused by drastic solar radiation fluctuations, but these leaves may also protect interior flowers from rain wash and UVB damage, and we do not know which one is the main function. In this study, we investigated whether rain and UVB protection are the main functions of overlapping leaves covering flowers and their potential impact on pollination. We first measured the intensities of UVB radiation in open air, beneath leaves and corollas, and then examined pollen susceptibility to different intensities of UVB and rain in the laboratory to estimate whether corollas per se protect interior pollen from UVB and rain damage. We also carried out pollination treatments and observed pollinator visitation of flowers with and without leaves in the field to assess whether the overlapping leaves covering flowers impair pollinator attraction. Our results showed that (1) water and strong UVB significantly decreased pollen germinability, but corollas per se could protect pollen from UVB and rain damage; (2) no autonomous self-pollination and apomixis occurred, and pollinators were essential for the reproduction of E. wallichii; however, flower coverage by overlapping leaves did not limit pollination. We suggested that rain and UVB protection was not the main function of overlapping leaves covered flowers, given that this protection can be provided by corollas per se. Alternatively, this extrafloral structure in E. wallichii may have evolved in response to extreme high temperatures associated with the strong solar radiation fluctuations. This indicates that, even in alpine plants, extreme high temperature may affect the evolution of plant extrafloral structures.

Involvement of Year‐to‐Year Variation in Thermal Time, Solar Radiation and Soil Available Moisture in Genotype‐by‐Environment Effects in Maize

Year‐to‐year variability in temperature, precipitation, and solar radiation is increasing due to global climate change. This enhanced variation will likely lead to more frequent and larger genotype‐by‐environment interaction (G × E) effects impacting genetic gains from selection. In this study G × E effects are examined in the absence of genetic variation for thermal time requirements (i.e., phenology), with an understanding of which physiological mechanisms are responsible for genotypic differences in grain yield, using a series of developmental windows, and in the context of fully characterized environments. Using a set of hybrid RILs of the classic Iodent × Stiff Stalk heterotic pattern, we demonstrate that the hybrid RILs are phenologically uniform and that grain yield differences are due primarily to genetic variation in dry matter accumulation during the grain filling period. We demonstrate that annual fluctuations in thermal time and solar radiation during key windows of development are causing G × E effects, and that variation in soil available water is not a major contributor to the G × E effects. Finally, we present evidence to support the concept that G × E effects resulting in crossover interactions occur due to how the genotypes respond to environmental factors that impact development, while G × E effects resulting in changes in magnitude arise due to variation in how genotypes respond to growth‐related environmental parameters.

Effect of working fluids on the performance of a novel direct vapor generation solar organic Rankine cycle system

A novel solar organic Rankine cycle (ORC) system with direct vapor generation (DVG) is proposed. A heat storage unit is embedded in the ORC to guarantee the stability of power generation. Compared with conventional solar ORCs, the proposed system avoids the secondary heat transfer intermediate and shows good reaction to the fluctuation of solar radiation. The technical feasibility of the system is discussed. Performance is analyzed by using 17 dry and isentropic working fluids. Fluid effects on the efficiencies of ORC, collectors and the whole system are studied. The results indicate that the collector efficiency generally decreases while the ORC and system efficiencies increase with the increment in fluid critical temperature. At evaporation temperature of 120 °C and solar radiation of 800 Wm−2, the ORC, collector and overall thermal efficiencies of R236fa are 10.59, 56.14 and 5.08% while their values for Benzene are 12.5, 52.58 and 6.57% respectively. The difference between collector efficiencies using R236fa and Benzene gets larger at lower solar radiation. The heat collection is strongly correlated with latent and sensible heat of the working fluid. Among the fluids, R123 exhibits the highest overall performance and seems to be suitable for the proposed system in the short term.

The Origin and Development of the Central European Man-made Landscape, Habitat and Species Diversity as Affected by Climate and its Changes – a Review

The Origin and Development of the Central European Man-made Landscape, Habitat and Species Diversity as Affected by Climate and its Changes – a Review

Redesigning Solar Water Pumping System at Giricahyo, Gunungkidul Regency, Yogyakarta: HOMER Analysis Approach

<p>HOMER, the software for micro-power applicable as renewable energy optimization, was used to analyze solar water pumping system based on deferrable-load and primary-load methods at Giricahyo. The 12 kWp solar PV and 30 kW generator were used to power the standing-aline system.. Unfortunately, the system has been idle since 2010. Research to redesign and analyse solar water pumping system has been conducted by Ministry of Public Works together with the Department of Physics Engineering UGM to bring it into normally. Furthermore, this study was aimed to obtain recommendation and to conduct analysis on system performance using HOMER. As a result in deferrable-load method, generator is inappropriate to be implemented because fossil fuel will be very expensive and rare. Besides, the 12 kWp Solar PV could meet 31.4 % of demand load. In primary-load method, capacity shortage of 1.5 kW pump is at 3.2 % and 3 kW pump is at 9.9 % which means that to deal with fluctuation of solar radiation the use of the 1.5 kW pumps were recommended. The demand that can be fulfilled by 1.5 kW pump is at 22.4 %. </p><p><strong>Keywords</strong>: capacity shortage; giricahyo; HOMER; redesign; solar water supply system.</p>

Optimized Operation-Planning of a Microgrid with Renewable Sources and Vehicle to Grid

<p>The microgrid with renewable sources possess stability issues. During the grid-connected mode, these issues are taken care by the external grid. However in case of islanding, the distributed generators within the microgrid, have to take care of these issues independently. It needs additional backup like diesel generation or battery storage, which increases the overall capital and operation costs. With the intervention of the V2G storage, these costs can be saved to some extent. However similar to the renewable sources like wind and solar, the power from V2G is also fluctuating which may lead the microgrid towards an uneconomical operation. Therefore an extensive operation-planning is needed to deal with these uncertainties, for the microgrid to be economically viable. In this context, the stochastic programming has been applied to achieve the optimum results. The stochastic scenarios for wind speed, solar radiation, V2G power and load fluctuation have been generated using the Markov chain Monte Carlo method. The optimized operation-planning aims to minimize the total net present cost, size of the fixed storage and fossil fuel emissions subject to constraints. The simulations have been performed using Matlab/Simulink, HOMER and Excel. The simulation results show that the V2G technology substantially decrease the total net present cost. Moreover for such a microgrid the total net present cost and fossil fuel emissions conflict with each other.</p>

Global change feed-back inhibits cyanobacterial photosynthesis.

Cyanobacteria are an important component of aquatic ecosystems, with a proliferation of massive cyanobacterial blooms predicted worldwide under increasing warming conditions. In addition to temperature, other global change related variables, such as water column stratification, increases in dissolved organic matter (DOM) discharge into freshwater systems and greater wind stress (i.e., more opaque and mixed upper water column/epilimnion) might also affect the responses of cyanobacteria. However, the combined effects of these variables on cyanobacterial photosynthesis remain virtually unknown. Here we present evidence that this combination of global-change conditions results in a feed-back mechanism by which, fluctuations in solar ultraviolet radiation (UVR, 280–400 nm) due to vertical mixing within the epilimnion act synergistically with increased DOM to impair cyanobacterial photosynthesis as the water column progressively darkens. The main consequence of such a feed-back response is that these organisms will not develop large blooms in areas of latitudes higher than 30°, in both the Northern and Southern Hemispheres, where DOM inputs and surface wind stress are increasing.

LakeMIP Kivu: evaluating the representation of a large, deep tropical lake by a set of one-dimensional lake models

The African great lakes are of utmost importance for the local economy (fishing), as well as being essential to the survival of the local people. During the past decades, these lakes experienced fast changes in ecosystem structure and functioning, and their future evolution is a major concern. In this study, for the first time a set of one-dimensional lake models are evaluated for Lake Kivu (2.28°S; 28.98°E), East Africa. The unique limnology of this meromictic lake, with the importance of salinity and subsurface springs in a tropical high-altitude climate, presents a worthy challenge to the seven models involved in the Lake Model Intercomparison Project (LakeMIP). Meteorological observations from two automatic weather stations are used to drive the models, whereas a unique dataset, containing over 150 temperature profiles recorded since 2002, is used to assess the model's performance. Simulations are performed over the freshwater layer only (60 m) and over the average lake depth (240 m), since salinity increases with depth below 60 m in Lake Kivu and some lake models do not account for the influence of salinity upon lake stratification. All models are able to reproduce the mixing seasonality in Lake Kivu, as well as the magnitude and seasonal cycle of the lake enthalpy change. Differences between the models can be ascribed to variations in the treatment of the radiative forcing and the computation of the turbulent heat fluxes. Fluctuations in wind velocity and solar radiation explain inter-annual variability of observed water column temperatures. The good agreement between the deep simulations and the observed meromictic stratification also shows that a subset of models is able to account for the salinity- and geothermal-induced effects upon deep-water stratification. Finally, based on the strengths and weaknesses discerned in this study, an informed choice of a one-dimensional lake model for a given research purpose becomes possible.

Blue Hill Observatory Sunshine: Assessment of Climate Signals in the Longest Continuous Meteorological Record in North America

The Blue Hill Meteorological Observatory occupies a unique place in the history of the American Meteorological Society and the development of atmospheric science. Through its 129-yr history, the observatory has been operated by founder Abbott Lawrence Rotch (1861–1912), Harvard University, and the National Weather Service, and it is presently run by the nonprofit Blue Hill Observatory Science Center. While daily temperature and precipitation records are available through the National Climatic Data Center, they do not include the full record of sunshine duration data that were measured using a Campbell–Stokes sunshine recorder. We have recently digitized the observatory's original daily sunshine archives, and now present the first full collection and analysis of sunshine records extending from 1889 to the present. This dataset is unique and salient to modern climate research because the collection represents the earliest and longest continuous measurements of insolation outside of western Europe. This record provides an unprecedented glimpse into regional climate features as well as important links between global phenomena and regional climate. Analysis reveals long-term fluctuations of cloud cover and solar radiation, including signals of regional industrialization, global dimming, volcanic eruptions, and the 11-yr solar cycle. Shorter-period fluctuations include evidence of an intricate annual pattern of sunshine duration and correlations with the Arctic Oscillation, the North Atlantic Oscillation, and galactic cosmic rays.

Techno-economic assessment of substituting natural gas based heater with thermal energy storage system in parabolic trough concentrated solar power plant

Parabolic-trough (PT) concentrated solar power (CSP) plants are very vulnerable to daily fluctuations in solar radiation. This dependence can be mitigated through a hybridization of solar energy with natural gas based heaters that supply thermal energy during the night or whenever solar irradiance level is dimmed. However, there is more sustainable way for CSP plants to avoid power-generation-outages caused by transient weather conditions, i.e. installation of thermal energy storage (TES). Such a system stores surplus thermal energy provided by solar field during sunny hours and discharges it when the sun is not available. Shams-1 PT plant in Madinat-Zayed, United-Arab-Emirates (UAE) has two natural gas based components, i.e. steam-booster heater and heat transfer fluid (HTF) heater. In the current study, model of Shams-1 was developed and analyzed in the System Advisor Model (SAM) software. It has been attempted to replace the HTF heater with TES. A parametric study has been conducted to determine the size of the TES as well as the solar field such that the specified power target demand would be satisfied. The results of the parametric analysis showed that TES can't completely replace the HTF heater, within reasonable sizes. Nevertheless, consequent simulations depicts that TES increases the capacity factor on one hand and decreases fuel consumption on the other hand.

Making Fuel While the Sun Shines

This article discusses the potential use of solar energy in various industrial processes. Solar energy is usually considered in terms of making electricity, but it also has the potential to replace fossil fuels in the production of liquid fuels, and in driving endothermic industrial processes. Solar thermochemical processes are feasible, and a solar power concentration process that harnesses sunlight's infrared energy is the best-suited technology for making solar fuels a reality. However, in spite of their appeal, solar thermochemical processes also have the same drawback that direct solar power has: the transient and diurnal nature of sunshine. Fluctuations of available solar radiation – over the course of a day, across different types of weather, and from season to season – present considerable challenges for potential solar-thermal systems. While there are economically affordable and commercially available solutions to some of those problems, substantial research and development is still required.

Electrodialysis Processes Assisted by Photovoltaic Panels. Concentration Control

This paper deals with the water desalination processes powered by renewable energy resources. An autonomous system based on electrodialysis technology and fed from photovoltaic panels is analyzed. Mathematical models for the several components, putting particular attention in the electrodialysis process, are developed. A control strategy based both in supervision control ideas and concepts of sliding modes is proposed. This allows guaranteeing the water quality beyond perturbations in the concentration and in the water flow in the cells input, as well as solar radiation fluctuations. Simulation results, which show the performance of the proposal, are presented.

Determination and analysis of phreatic water evaporation in extra-arid dune region

Extra-arid desert is a terminal of biological geochemistry circulation system. It has important value in scientific research and huge new discoveries, which is very useful in many regions, such as energy resources, mineral, water resources, ecology, biodiversity, tourism and characteristic agriculture. Meanwhile, extra-arid area’s desertification is a serious threat to the ecological safety of earth. Aeolian desertification is one of style of desertification caused by water shortage. Once desert has formed, it is very difficult to management or recovery. One of most effective methods for desert control is using integrated ecosystem management based on considering water and the soil. Therefore, it is very important to find a new available water resource, and authors’ research is in this field. In this paper, we select a Gobi on Dunhuang Mogao Grottoes of Kumtag desert fringe, where the buried depth of phreatic water is over 200m. Using an arched shed-air conditioning system, where covered drift sand thickness of 2.0m, the phreatic evaporation was measured for the first time. In order to analyze influence factors, the evaporation of phreatic water on Gobi was measured and compared. The temperature of soil and air, the humidity inside and outside of the arched shed were also monitored. It is found that the phreatic water under sand can go through sand layer and get to surface, which forms evaporation. The amount of evaporation changes along with solar radiation and temperature fluctuations in the day. It also changes periodically in the year. During five months from June to October, the sunshine time is longer and temperature is higher, and the evaporation is higher too, and the mean daily evaporation is 3.6g/(m2d). In other periods, the amount of evaporation of phreatic water is extremely weak. It is difficult to monitor by the arched shed-air conditioning system. Compared with Gobi region, the amount of evaporation of phreatic water on dune is very low, which is only 15.0% evaporation on Gobi. The key reason is the difference of salts in soil. The crystal water could be decomposed from salts or combined again. This reversible process plays a key role in transferring phreatic water of dune and Gobi. The amount of phreatic evaporation is proportional to the salts content in shallow soil. The salts content in dune is only 0.7% of salts content in Gobi, and water content in dune is 3.2% of the Gobi soil. According to results of monitoring, the water content is low in sand. The crystal water in shifting sand could be completely decomposed from salts with temperature rising. It causes relative humidity (RH) decreasing, which is inversely in the sand compared to in Gobi soil. In depth of 10cm sand, the daily fluctuation is about 10%, which is significantly higher than that of in Gobi soil (3%). As the crystalline salt is a kind of typical water carrier, decreasing the content of crystalline salt results to reduce water transporting because carrying capacity of water is significantly reduced. After condensing and collecting 168days, 9808g of water was outputted from sand. However, the water content in sand was still obviously higher than original content. That means the underground vapor migrates upward, and the phreatic water moves to surface. From the evaporation comparison of dune and Gobi, we can conclude that the amount of evaporation could be controlled by changing the soil property in interface, this points out the direction for utilization of phreatic water evaporation.

Environmental fluctuations in the northwestern Pacific Ocean during the last interglacial period: Evidence from radiolarian assemblages

Abstract The last interglacial period, from 130 to 117 ka, was as warm as or warmer than the present, and thus it is relevant for our understanding of the possible effects of recent global warming. In this study, we used radiolarian assemblages in a sediment core to reconstruct environmental fluctuations in the northwestern Pacific Ocean during the last interglacial period. The sediment core (MD012421) was collected where the warm Kuroshio Current meets the cold Oyashio Current. We used the ratio of warm-water to the total of warm- and cool-water radiolarian species (Tr) as an indicator of the dominant surface water masses (relative importance of the warm Kuroshio and cool Oyashio Currents), and we used the relative abundance of Cycladophora davisiana as an indicator of cold, oxygen-rich intermediate waters related to seasonal sea ice formation at high latitudes. Tr results indicated that a transitional surface water mass off Kashima was replaced by a subtropical water mass between 131 ka (late Marine Isotope Stage [MIS] 6) and 125 ka (last interglacial period; MIS 5e). Furthermore, the relative abundance of C. davisiana changed from 19.6% at 133 ka (late MIS 6) to ~ 0% at 126 ka (MIS 5e); this change suggests a reduction of cold, oxygen-rich waters at intermediate depths off Kashima in association with weakened ventilation at high latitudes in the North Pacific. As this reduction took place ~ 1 kyr earlier than the shift of surface water masses at the core site, we inferred that changes of insolation (the main driver of glacial–interglacial cycles) controlling the variation of sea ice formation at high latitudes occurred earlier than the lower latitude change in the atmospheric pressure pattern controlling the surface water shifts. High-resolution time-series analysis indicated that fluctuations in the surface water mass occurred cyclically, with a periodicity of approximately 500 years during the second half of the last interglacial period. This periodicity may be attributable to fluctuations in solar radiation.

Multiple Criteria for Evaluating Pollinator Performance in Highbush Blueberry (Ericales: Ericaceae) Agroecosystems

Numerous bee species provide pollination services in agricultural ecosystems. Evaluating a pollinator's performance with regard to a crop is an important step in attributing pollination services and predicting how changes in a bee community or foraging environment will affect those services. We used multiple criteria to evaluate pollinators of North Carolina highbush blueberry, Vaccinium corymbosum L., agroecosystems. For five groups of bees (Apis mellifera L., Bombus spp., Habropoda laboriosa F., small native bees, and Xylocopa virginica L.), we measured forager abundance through transect observations, quantified per-visit efficiency as viable seed set resulting from a single visit, and analyzed bee presence in different weather conditions. We also considered two other criteria affecting pollinator performance-visitation rate and interspecific influence. A. mellifera was the most abundant bee in the majority of our survey sites, yet had low per-visit efficiency and reduced foraging activity in inclement weather. Small native bees were highly efficient pollinators. Their visits resulted in nearly twice as many seeds as A. mellifera or H. laboriosa. Bombus spp., H. laboriosa, and small native bees were more resilient to fluctuations in temperature, wind speed, and solar radiation than A. mellifera. Although nectar-robbing X. virginica contributed to little pollination through direct flower visits, their presence within the crop impacts the behavior and performance of other individuals. Underscoring the importance of evaluating pollinator performance via multiple criteria, our results show that bee groups contribute to pollination in different ways. These differences may provide functional complementarity and stability of pollination services to agricultural systems.

Importance of underwater light field in selecting phytoplankton morphology in a eutrophic reservoir

This study attempted to reveal the effect of solar radiation fluctuation on the dynamics of phytoplankton communities expressed as cell morphology in eutrophic water bodies where the impacts of nutrients could be considered as small. Two morphological descriptors were proposed, cellular projected area ( $$\varphi_{\rm p}$$ ) and flattening index (f), which were able to he cellular light-harvesting potential and energy requirement, respectively. A model was established to describe the effects of natural light availability on selecting phytoplankton assemblages with underwater field and mixing process in the water column considered. Based on the data collected from the eutrophic Yanghe Reservoir, the model was derived as $$V=37.92\lambda\varphi_{\rm p} (R^2 = 0.673, P < 0.01),$$ where V is bio-volume, λ is a function of solar elevation angle (θ) and mixing/euphotic depth ratio (z mix/z eu) in water, and $$\varphi_{\rm p}.$$ Post-analysis of the model results revealed that species with large $$\varphi_{\rm p}$$ and f in general have advantages in spring and winter when underwater light availability is low; by contrast, those with small $$\varphi_{\rm p}$$ and f have advantages in summer. Larger $$\varphi_{\rm p}$$ and f mean that the cells could harvest more light energy and consumed less, allowing them to be selected under low light availability; and vice versa. We thus concluded that the underwater light field probably the most important factor in selecting phytoplankton morphology in eutrophic water bodies.

Static and Dynamic Characteristic Models of Global Solar Radiation Fluctuation in the Scope of Load Frequency Control

SUMMARYPenetration of photovoltaic (PV) generation system into the power system may have some negative effects on stable operations of the power system; for example, on frequency control. Therefore, investigation of the short‐term fluctuations of PV generation is important as a precaution for further PV penetration. Since PV generation is approximately proportional to the incident solar radiation, this paper develops static and dynamic characteristic models for short‐term fluctuations of global solar radiation. The static characteristic model is a set of standard deviations which have been statistically estimated based on past observed data. The dynamic characteristic model consists of autoregressive models which are designed for actually observed time‐sequential short‐term fluctuation data. In both models, the clearness index is used to eliminate seasonal variation of solar radiation. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(2): 10–20, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22469

Season of infectious mononucleosis and risk of multiple sclerosis at different latitudes; the EnvIMS Study

Background: Seasonal fluctuations in solar radiation and vitamin D levels could modulate the immune response against Epstein-Barr virus (EBV) infection and influence the subsequent risk of multiple sclerosis (MS). Methods: Altogether 1660 MS patients and 3050 controls from Norway and Italy participating in the multinational case-control study of Environmental Factors In Multiple Sclerosis (EnvIMS) reported season of past infectious mononucleosis (IM). Results: IM was generally reported more frequently in Norway (p=0.002), but was associated with MS to a similar degree in Norway (odds ratio (OR) 2.12, 95% confidence interval (CI) 1.64–2.73) and Italy (OR 1.72, 95% CI 1.17–2.52). For all participants, there was a higher reported frequency of IM during spring compared to fall (p<0.0005). Stratified by season of IM, the ORs for MS were 1.58 in spring (95% CI 1.08–2.31), 2.26 in summer (95% CI 1.46–3.51), 2.86 in fall (95% CI 1.69–4.85) and 2.30 in winter (95% CI 1.45–3.66). Conclusions: IM is associated with MS independently of season, and the association is not stronger for IM during spring, when vitamin D levels reach nadir. The distribution of IM may point towards a correlation with solar radiation or other factors with a similar latitudinal and seasonal variation.