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Journal ArticleDOI

Estimation of Global Solar Radiation for Four Selected Sites in Nepal Using Sunshine Hours, Temperature and Relative Humidity

30 Aug 2013-Journal of Power and Energy Engineering (Scientific Research Publishing)-Vol. 01, Iss: 3, pp 1-9
TL;DR: In this article, a linear regression technique has been used to develop a model for Biratnagar, Kathmandu, Pokhara and Jumla, which has calculated the global solar radiation for these locations.
Abstract: Rational and accurate solar energy databases, essential for designing, sizing and performing the solar energy systems in any part of the world, are not easily accessible in different localities of Nepal. In this study, daily global solar radiation, sunshine hours and meteorological data for Biratnagar, Kathmandu, Pokhara and Jumla have been used to derive the regression constants. The linear regression technique has been used to develop a model for Biratnagar, Kathmandu, Pokhara and Jumla. The model has calculated the global solar radiation for these locations. The values of global solar radiation estimated by the model are found to be in close agreement with measured values of respective sites. The estimated values were compared with Angstrom-Prescott model and examined using the root mean square error (RMSE), mean bias error (MBE), mean percentage error (MPE), coefficient of regression (R), coefficient of determinant (R 2 ) and correlation coefficient (CC) statistical techniques. Thus, the resultant correlations and linear regression relations may be then used for the locations of similar meteorological/geographical characteristics and also can be used to estimate the missing data of solar radiation for the respective site.

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Citations
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Journal ArticleDOI
TL;DR: In this article, the current energy production and consumption profiles are reviewed, and the main factors contributing to a widening gap between the energy supply and demand are identified, such as delayed and overpriced hydropower projects, outdated and insufficient energy infrastructure, transmission and distribution losses, energy theft, deficient energy management, lack of energy conservation, low efficiency of equipment, unsustainable energy pricing strategies and unsatisfying energy market regulations.
Abstract: Nepal has been suffering from a serious energy crisis for decades. It has severely affected its economic, social and political developments. Owing to the continuously evolving energy situation in Nepal, and the recent progress in renewable energy technologies, this study aims to provide an up to date perspective on the current energy crisis in Nepal. In particular, the current energy production and consumption profiles are reviewed, and the main factors contributing to a widening gap between the energy supply and demand are identified. These factors concern delayed and overpriced hydropower projects, outdated and insufficient energy infrastructure, transmission and distribution losses, energy theft, deficient energy management, lack of energy conservation, low efficiency of equipment, unsustainable energy pricing strategies and unsatisfying energy market regulations. Other essential factors worsening the energy crisis can be attributed to specific geographical and geopolitical problems, the strong dependence on energy imports, and inadequate exploitation of the vast amounts of renewable energy resources. The status of existing and planned large hydropower projects is summarized. The recent policies and investment initiatives of the Nepalese government to support green and sustainable energy are discussed. Furthermore, a long-term outlook on the energy situation in Nepal is outlined using the energy modeling software LEAP in order to show how to exploit the tremendous renewable energy resources in Nepal. Our findings suggest that renewable resources are crucial not only for mitigating the present energy crisis, but also to ultimately provide energy independence for Nepal by establishing reliable and secure sources of energy.

133 citations

Journal ArticleDOI
A. Suman1
TL;DR: In this paper, the authors reviewed various types of renewable energy technologies and their status, potential for adoption, relationship to climate change, and mitigative and adaptive roles in Nepal and recommended that the government of Nepal focus work on energy policy reviews to address local energy demand and climate change issues by utilizing renewable energy resources at the local level.
Abstract: Renewable energy plays a crucial role in both climate change mitigation and adaptation in highly climate-vulnerable nations such as Nepal. This paper reviews various types of renewable energy technologies and their status, potential for adoption, relationship to climate change, and mitigative and adaptive roles in Nepal. Nepal has installed micro-hydro projects, solar power, improved cooking stoves, biogas technology, improved water mills, and wind energy to mitigate and adapt to climate change. There is a growing potential for renewable energy development in Nepal, such as hydropower, solar, wind energy, biogas, and improved cooking stoves. Roughly 70% of Nepal's energy consumption is generated from traditional energy sources while renewable energy accounts for approximately three percent. The gradual increase in the use of renewable energy has reduced greenhouse gas emissions and enhanced carbon sequestration. By adopting renewable energy technologies, Nepal has reduced emissions by 221,129 tCO2e from 2017 to 2018. Nepal's second Nationally Determined Contribution targets a 15% increase in national energy use from renewables with a reduction of 23% of CO2 emissions by 2030 using biogas and improved cooking systems. Furthermore, a significant increase in the adoption of renewable energy has become a pivotal strategy in adaptation to climate change in social, health, and economic sectors resulting in time savings, alternative income sources, improved health and educational status, local job opportunities, and the promotion of social capital. The benefits of adapting to climate change and mitigating CO2 emissions via renewable energy are significant at the local, national, and international levels. This study recommends that the government of Nepal focus work on energy policy reviews to address local energy demand and climate change issues by utilizing renewable energy resources at the local level, which has global implications.

56 citations

Journal ArticleDOI
Abstract: Monitoring and prediction of the climatic phenomenon are of keen interest in recent years because it has great influence in the lives of people and their environments. This paper is aimed at reporting the variation of daily and monthly solar radiation, air temperature, relative humidity (RH), and dew point over the year of 2013 based on the data obtained from the weather station situated in Damak, Nepal. The result shows that on a clear day, the variation of solar radiation and RH follows the Gaussian function in which the first one has an upward trend and the second one has a downward trend. However, the change in air temperature satisfies the sine function. The dew point temperature shows somewhat complex behavior. Monthly variation of solar radiation, air temperature, and dew point shows a similar pattern, lower at winter and higher in summer. Maximum solar radiation (331 Wm-2) was observed in May and minimum (170 Wm-2) in December. Air temperature and dew point had the highest value from June to September nearly at 29°C and 25°C, respectively. The lowest value of the relative humidity (55.4%) in April indicates the driest month of the year. Dew point was also calculated from the actual readings of air temperature and relative humidity using the online calculator, and the calculated value showed the exact linear relationship with the observed value. The diurnal and nocturnal temperature of each month showed that temperature difference was relatively lower (less than 10°C) at summer rather than in winter.

31 citations

Journal ArticleDOI
TL;DR: In this article, eleven regression models grouped into three main categories: sunshine-based, temperature-based and hybrid-parameter-based are investigated using twenty-nine years meteorological data which include sunshine hours, temperature and relative humidity for fifteen stations on the island.

30 citations

Journal ArticleDOI
TL;DR: Age was the most important predictor for 25( OH)D concentration, and there were no differences in 25(OH)D concentrations during illness and after 14, 45, and 90 days when adjusting for age.
Abstract: Poor vitamin D status has been associated with increased risk and severity of respiratory tract infections. Whether or not inflammation and infection affects 25-hydroxy vitamin D (25(OH)D) concentration is controversial and is important in the interpretation of observational studies using plasma-25(OH)D as a biomarker for status. Our objectives were to measure whether 25(OH)D concentration was altered by an episode of acute lower respiratory tract infection and whether markers of inflammation predicted the 25(OH)D concentration. Children aged 2-35 months with severe (n = 43) and non-severe (n = 387) community-acquired, WHO-defined pneumonia were included. 25(OH)D concentration and inflammatory markers (cytokines, chemokines, and growth factors) were measured in plasma during the acute phase and 14, 45, and 90 days later. Predictors for 25(OH)D concentrations were identified in multiple linear regression models. Mean 25(OH)D concentration during the acute phase and after recovery (14, 45, and 90 days) was 84.4 nmol/L ± 33.6, and 80.6 ± 35.4, respectively. None of the inflammatory markers predicted 25(OH)D concentration in the multiple regression models. Age was the most important predictor for 25(OH)D concentration, and there were no differences in 25(OH)D concentrations during illness and after 14, 45, and 90 days when adjusting for age. Infection and inflammation did not alter the 25(OH)D concentration in young children with acute lower respiratory tract infections.

20 citations

References
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Book
01 Jan 1983

3,218 citations


"Estimation of Global Solar Radiatio..." refers background or methods in this paper

  • ...The sum of direct and diffuse radiation on the earth surface is known as global/total radiation which is very important for the design of certain solar energy applications [10]....

    [...]

  • ...…regression constants, the ratio m O H H is clearness parameter or cloudiness index, d n N fraction of sunshine hours, and OH is the monthly average daily extraterrestrial radia- tion on the horizontal surface given by Iqbal (1983) as follows: sin si24 π π 18 n cos co si 0 s nO o ssc sH I E...

    [...]

  • ...…of the estimated values was tested by using the statistical techniques for the Angstrom-Prescott model and for the new proposed model based on the definition devised by Iqbal (1983) which is as below: 1 22n 1 e mRMSE H H n (13) 1n e mMBE H H n (14) 1 100 n m e m H HMPE n H (15)...

    [...]

  • ...The depletion of the direct beam by the cloud depends on the type of clouds, their thickness and the number of layers [10]....

    [...]

Journal ArticleDOI
TL;DR: In this article, a chronologically collected and reviewed the extensive global solar radiation models available in the literature and to classify them into four categories, i.e., sunshine-based, cloudbased, temperature-based and other meteorological parameter-based models, based on the employed meteorological parameters as model input.
Abstract: Solar radiation is a primary driver for many physical, chemical, and biological processes on the earth’s surface. Solar energy engineers, architects, agriculturists, hydrologists, etc. often require a reasonably accurate knowledge of the availability of the solar resource for their relevant applications at their local. In solar applications, one of the most important parameters needed is the long-term average daily global irradiation. For regions where no actual measured values are available, a common practice is to estimate average daily global solar radiation using appropriate empirical correlations based on the measured relevant data at those locations. These correlations estimate the values of global solar radiation for a region of interest from more readily available meteorological, climatological, and geographical parameters. The main objective of this study is to chronologically collect and review the extensive global solar radiation models available in the literature and to classify them into four categories, i.e., sunshine-based, cloud-based, temperature-based, and other meteorological parameter-based models, based on the employed meteorological parameters as model input. Furthermore, in order to evaluate the accuracy and applicability of the models reported in this paper for computing the monthly average daily global solar radiation on a horizontal surface, the geographical and meteorological data of Yazd city, Iran was used. The developed models were then evaluated and compared on the basis of statistical error indices and the most accurate model was chosen in each category. Results revealed that all the proposed correlations have a good estimation of the monthly average daily global solar radiation on a horizontal surface in Yazd city, however, the El-Metwally sunshine-based model predicts the monthly averaged global solar radiation with a higher accuracy.

388 citations


"Estimation of Global Solar Radiatio..." refers background in this paper

  • ...Empirical models which have been used to calculate solar radiation are usually based on astronomical factors, geographical factors, geometric factors, physical factors and meteorological factors [14]....

    [...]

  • ...The database of the solar radiation at any locations is very useful for that particular locality as well as for the broader world community [14] for a sustainable future energy....

    [...]

Journal ArticleDOI
TL;DR: In this paper, the authors developed correlation models to estimate the monthly average global solar radiation on horizontal surfaces using the sunshine hour and temperature data, which can be used for designing and evaluating the performance of solar energy systems including passive solar buildings.
Abstract: Solar radiation data, a prerequisite for the designing and sizing of solar energy systems, are not available in many Indian locations. However, the sunshine hour or temperature data are available for most sites from which solar radiation can be computed. New correlation models have been developed; incorporating the latitude and altitude of a site to estimate the monthly average global solar radiation on horizontal surfaces using the sunshine hour and temperature data. The models are used for computing values of six Indian stations with different geographical locations, based on 10-15 years of data. The estimated values are found to be in close agreement with their measured values. The estimated data are also compared with the results using other models to test the accuracy of new models. It has been shown that the estimated values of global radiation using temperature data are also sufficiently accurate and can be utilized for sites for which even sunshine hour data are not measured. This will lead to better inputs for designing and evaluating the performance of solar energy systems including passive solar buildings.

81 citations


"Estimation of Global Solar Radiatio..." refers background in this paper

  • ...So far, various models have been developed by a number of researchers with different regression coefficients using linear regression techniques [13] for various countries and for different locations to estimate solar radiation....

    [...]

Journal ArticleDOI
TL;DR: The possibility of installing solar energy devices such as air conditioning plants, solar desalination stills, etc. in remote parts of Australia has led to the necessity of predicting solar radiation in places where no measurements have been made as mentioned in this paper.

71 citations


"Estimation of Global Solar Radiatio..." refers background in this paper

  • ...It is an equation of least square line [15] or first order regression [16] where, KT (= Hm/Ho) is a dependent variable called clearness index, a, b, c, d are regression constants, and...

    [...]

01 Jan 2009
TL;DR: In this paper, the global solar radiation and the measured solar radiation were tested using the mean bias error (MBE), root mean square error (RMSE), and mean percentage error (MPE) statistical techniques.
Abstract: The monthly mean daily data for global solar radiation and sunshine hours for a period of seventeen years (1999 - 2007) for Calabar, Enugu and Port Harcourt respectively have been used to develop a number of regression equations. The values of the global solar radiation estimated by the models and the measured solar radiation were tested using the mean bias error (MBE), root mean square error (RMSE) and mean percentage error (MPE) statistical techniques. The values of the correlation coefficient (R) and coefficient of determination (R 2 ) were also determined for each equation. The equations with the highest values of R, R 2 and least values of MBE, RMSE and MPE for Calabar, Port

47 citations


"Estimation of Global Solar Radiatio..." refers methods in this paper

  • ...The resultant correlation may then be used for locations of similar meteorological characteristics [12]....

    [...]