Solar Energy Fundamentals, Zekai ¸Sen

Solar Energy Fundamentals, Zekai ¸Sen

(Parte 1 de 8)

Solar Energy Fundamentals and Modeling Techniques

Zekai Sen

Solar Energy Fundamentals and Modeling Techniques

Atmosphere, Environment, Climate Change and Renewable Energy

Prof. Zekai Sen Istanbul Technical University Faculty of Aeronautics and Astronautics Dept. Meteorology Campus Ayazaga 34469 Istanbul Turkey

British Library Cataloguing in Publication Data Sen, Zekai

Solar energy fundamentals and modeling techniques : atmosphere, environment, climate change and renewable energy 1. Solar energy I. Title 621.4’7 ISBN-13: 9781848001336

Library of Congress Control Number: 2008923780 © 2008 Springer-Verlag London Limited

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the publishers.

The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore free for general use.

The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made.

Cover design: eStudio Calamar S.L., Girona, Spain Printed on acid-free paper 987654 321


In the name of Allah the most merciful and the most beneficial


Atmospheric and environmental pollution as a result of extensive fossil fuel exploitation in almost all human activities has led to some undesirable phenomena that have not been experienced before in known human history. They are varied and include global warming, the greenhouse affect, climate change, ozone layer depletion, and acid rain. Since 1970 it has been understood scientifically by experiments and research that these phenomena are closely related to fossil fuel uses because they emit greenhousegases such as carbon dioxide (CO2) and methane (CH4) which hinder the long-wave terrestrial radiation from escaping into space and, consequently, the earth troposphere becomes warmer. In order to avoid further impacts of these phenomena, the two main alternatives are either to improve the fossil fuel quality thus reducing their harmful emissions into the atmosphere or, more significantly, to replace fossil fuel usage as much as possible with environmentally friendly, clean, and renewable energy sources. Among these sources, solar energy comes at the top of the list due to its abundance and more even distribution in nature than other types of renewable energy such as wind, geothermal, hydropower, biomass, wave, and tidal energy sources. It must be the main and common purpose of humanity to develop a sustainable environment for future generations. In the long run, the known limits of fossil fuels compel the societies of the world to work jointly for their replacement gradually by renewable energies rather than by improving the quality of fossil sources.

Solar radiation is an integral part of different renewable energy resources, in general, and, in particular, it is the main and continuous input variable from the practically inexhaustible sun. Solar energy is expected to play a very significant role in the future especially in developing countries, but it also has potential in developed countries. The material presented in this book has been chosen to provide a comprehensive account of solar energy modeling methods. For this purpose, explanatory background material has been introduced with the intention that engineers and scientists can benefit from introductory preliminaries on the subject both from application and research points of view.

The main purpose of Chapter 1 is to present the relationship of energy sources to various human activities on social, economic and other aspects. The atmospheric vii viii Preface environment and renewable energy aspects are covered in Chapter 2. Chapter 3 provides the basic astronomical variables, their definitions and uses in the calculation of the solar radiation (energy) assessment. These basic concepts, definitions, and derived astronomical equations furnish the foundations of the solar energy evaluation at any given location. Chapter 4 provides first the fundamental assumptions in the classic linear models with several modern alternatives. After the general review of available classic non-linear models, additional innovative non-linear models are presented in Chapter 5 with fundamental differences and distinctions. Fuzzy logic and genetic algorithm approaches are presented for the non-linear modeling of solar radiation from sunshine duration data. The main purpose of Chapter 6 is to present and develop regional models for any desired location from solar radiation measurement sites. The use of the geometric functions, inverse distance, inverse distance square, semivariogram, and cumulative semivariogram techniques are presented for solar radiation spatial estimation. Finally, Chapter 7 gives a summary of solar energy devices.

Applications of solar energy in terms of low- and high-temperature collectors are given with future research directions. Furthermore, photovoltaic devices are discussed for future electricity generation based on solar power site-exploitation and transmission by different means over long distances, such as fiber-optic cables. Another future use of solar energy is its combination with water and, as a consequence, electrolytic generation of hydrogen gas is expected to be another source of clean energy. The combination of solar energy and water for hydrogen gas production is called solar-hydrogen energy. Necessary research potentials and application possibilities are presented with sufficient background. New methodologies that are bound to be used in the future are mentioned and, finally, recommendations and suggestions for future research and application are presented, all with relevant literature reviews. I could not have completed this work without the support, patience, and assistance of my wife Fatma Sen.

Istanbul, Çubuklu 15 October 2007

1 Energy and Climate Change1
1.1 General1
1.2 Energya nd Climate3
1.3 Energya nd Society5
1.4 Energy and Industry10
1.5 Energy and the Economy12
1.6 Energya nd the Atmospheric Environment13
1.7 Energya nd the Future17
2 Atmospheric Environment and Renewable Energy21
2.1 General21
2.2 Weather, Climate, and Climate Change2
2.3 Atmosphere and Its Natural Composition26
2.4 Anthropogenic Composition of the Atmosphere28
2.4.1 Carbon Dioxide (CO2)29
2.4.2 Methane (CH4)30
2.4.3 Nitrous Oxide (N2O)31
2.4.4 Chlorofluorocarbons (CFCs)31
2.4.5 Water Vapor (H2O)31
2.4.6 Aerosols3
2.5 EnergyD ynamics in the Atmosphere34
2.6 Renewable Energy Alternatives and Climate Change35
2.6.1 Solar Energy36
2.6.2 Wind Energy37
2.6.3 HydropowerE nergy38
2.6.4 Biomass Energy39
2.6.5 Wave Energy40
2.6.6 HydrogenE nergy41
2.7 EnergyU nits43

Contents ix

3 Solar Radiation Deterministic Models47
3.1 General47
3.2 The Sun47
3.3 Electromagnetic (EM) Spectrum51
3.4 EnergyB alance of the Earth5
3.5 Earth Motion57
3.6 Solar Radiation61
3.6.1 Irradiation Path64
3.7 Solar Constant6
3.8 Solar Radiation Calculation67
3.8.1 Estimation of Clear-Sky Radiation70
3.9 Solar Parameters72
3.9.1 Earth’s Eccentricity72
3.9.2 Solar Time72
3.9.3 Useful Angles74
3.10 Solar Geometry7
3.10.1 Cartesian and Spherical Coordinate System78
3.1 Zenith Angle Calculation85
3.12 Solar EnergyC alculations87
3.12.1 Daily Solar Energyo n a Horizontal Surface8
3.12.2 Solar Energy on an Inclined Surface91
3.12.3 Sunrise and Sunset Hour Angles93
4 Linear Solar Energy Models101
4.1 General101
4.2 Solar Radiation and Daylight Measurement102
4.2.1 InstrumentE rror and Uncertainty103
4.2.2 OperationalE rrors104
4.2.3 Diffuse-Irradiance Data Measurement Errors105
4.3 Statistical Evaluationo f Models106
4.3.1 Coefficient of Determination (R2)109
4.3.2 Coefficient of Correlation (r)110
and Root Mean Square Error1
4.3.4 Outlier Analysis112
4.4 Linear Model113
4.4.1 Angström Model (AM)116
4.5 Successive Substitution (S) Model120
4.6 Unrestricted Model (UM)126
4.7 Principal Component Analysis (PCA) Model133
4.8 Linear Cluster Method (LCM)140
5 Non-Linear Solar Energy Models151
5.1 General151
5.2 Classic Non-Linear Models151
5.3 Simple Power Model (SPM)156
5.3.1 Estimation of Model Parameters157
5.4 Comparison of Different Models159
5.5 Solar Irradiance Polygon Model (SIPM)160
5.6 Triple Solar Irradiation Model (TSIM)168
5.7 Triple Drought–Solar Irradiation Model (TDSIM)172
5.8 Fuzzy Logic Model (FLM)176
5.8.1 Fuzzy Sets and Logic177
5.8.2 Fuzzy Algorithm Applicationf or Solar Radiation179
5.9 Geno-Fuzzy Model (GFM)186
5.10 Monthly Principal Component Model (MPCM)188
5.1 Parabolic Monthly Irradiation Model (PMIM)196
5.12 Solar Radiation Estimation from Ambient Air Temperature202
6 Spatial Solar Energy Models209
6.1 General209
6.2 Spatial Variability210
6.3 Linear Interpolation212
6.4 Geometric Weighting Function214
6.5 Cumulative Semivariogram (CSV) and Weighting Function216
6.5.1 Standard Spatial DependenceF unction (SDF)217
6.6 Regional Estimation220
6.6.1 Cross-Validation221
6.6.2 Spatial Interpolation226
6.7 General Application228
7 Solar Radiation Devices and Collectors239
7.1 General239
7.2 Solar Energy Alternatives239
7.3 Heat Transfer and Losses241
7.3.1 Conduction242
7.3.2 Convection243
7.3.3 Radiation244
7.4 Collectors245
7.4.1 Flat Plate Collectors246
7.4.2 Tracking Collectors249
7.4.3 Focusing (Concentrating) Collectors250
7.4.4 Tilted Collectors252
7.4.5 Solar Pond Collectors253
7.5 Photovoltaic (PV) Cells256
7.6 Fuel Cells259
7.7 HydrogenS torage and Transport259
7.8 Solar Energy Home260
7.9 Solar Energy and Desalination Plants261
7.10 Future Expectations262
A A Simple Explanation of Beta Distribution267
B A Simple Power Model269

Chapter 1 Energy and Climate Change

Energy and fresh water are the two major commodities that furnish the fundamentals of every human activity for a reasonable and sustainable quality of life. Energy is the fuel for growth, an essential requirement for economic and social development. Solar energy is the most ancient source and the root for almost all fossil and renewable types. Special devices have been used for benefiting from the solar and other renewable energy types since time immemorial. During the early civilizations water and wind power have been employed as the major energy sources for navigation, trade, and information dissemination. For instance, Ebul-Iz Al-Jazari (1136– 1206), as mentioned by Sen (2005), was the first scientist who developed various instruments for efficient energy use. Al-Jazari described the first reciprocating piston engine, suction pump, and valve, when he invented a two-cylinder reciprocating suction piston pump, which seems to have had a direct significance in the development of modern engineering. This pump is driven by a water wheel (water energy) that drives, through a system of gears, an oscillating slot-rod to which the rods of two pistons are attached. The pistons work in horizontally opposed cylinders, each provided with valve-operated suction and delivery pipes. His original drawing in Fig. 1.1a shows the haulage of water by using pistons, cylinders, and a crank moved by panels subject to wind power. In Fig. 1.1b the equivalent instrument design is achieved by Hill (1974).

Ebul-Iz Al-Jazari’s original robotic drawing is presented in Fig. 1.2. It works with water power through right and left nozzles, as in the figure, and accordingly the right and left hands of the human figure on the elephant move up and down.

In recent centuries the types and magnitudes of the energy requirements have increased in an unprecedented manner and mankind seeks for additional energy sources. Today, energy is a continuous driving power for future social and technological developments. Energy sources are vital and essential ingredients for all human transactions and without them human activity of all kinds and aspects cannot be progressive. Population growth at the present average rate of 2% also exerts extra pressure on limited energy sources.

Zekai Sen, Solar Energy Fundamentals and Modeling Techniques 1 DOI: 10.1007/978-1-84800-134-3, ©Springer 2008

2 1 Energy and Climate Change Fig. 1.1 a Al-Jazari (1050). b Hill (1974)

The oil crises of the 1970s have led to a surge in research and development of renewable and especially solar energy alternatives. These efforts were strongly correlated with the fluctuating market price of energy and suffered a serious setback as this price later plunged. The missing ingredient in such a process was a long-

1.2 Energy and Climate 3 term perspective that hindered the research and developmentpolicy within the wider context of fossil and solar energy tradeoffs rather than reactions to temporary price fluctuations. The same events also gave rise to a rich literature on the optimal exploitation of natural resources, desirable rate of research, and development efforts to promote competitive technologies (Tsur and Zemel 1998). There is also a vast amount of literature on energy management in the light of atmospheric pollution and climate change processes (Clarke 1988; Edmonds and Reilly 1985, 1993; Hoel and Kvendokk 1996; Nordhaus 1993, 1997; Tsur and Zemel 1996; Weyant 1993).

The main purpose of this chapter is to present the relationship of energy sources to various human activities including social, economic, and other aspects.

1.2 Energy and Climate

In the past, natural weather events and climate phenomena were not considered to be interrelated with the energy sources, however during the last three decades their close interactions become obvious in the atmospheric composition, which drives the meteorological and climatologic phenomena. Fossil fuel use in the last 100 years has loaded the atmosphere with additional constituents and especially with carbon dioxide (CO2), the increase of which beyond a certain limit influences atmospheric events (Chap. 2). Since the nineteenth century, through the advent of the indus- trial revolution, the increased emissions of various greenhouse gases (CO2,C H4,

N2O, etc.) into the atmosphere have raised their concentrations at an alarming rate, causing an abnormal increase in the earth’s average temperature. Scientists have confirmed, with a high degree of certainty, that the recent trend in global average temperatures is not a normal phenomenon (Rozenzweig et al., 2007). Its roots are to be found in the unprecedented industrial growth witnessed by the world economy, which is based on energy consumption.

Since climate modification is not possible, human beings must be careful in their use of energy sources and reduce the share of fossil fuels as much as possible by replacing their role with clean and environmentally friendly energy sources that are renewable, such as solar, wind, water, and biomass. In this manner, the extra loads on the atmosphere can be reduced to their natural levels and hence sustainability can be passed on to future generations.

Over the last century, the amount of CO2 in the atmosphere has risen, driven in large part by the usage of fossil fuels, but also by other factors that are related to rising population and increasing consumption, such as land use change, etc.O nt he global scale, increase in the emission rates of greenhouse gases and in particular

CO2 represents a colossal threat to the world climate. Various theories and calculations in atmospheric research circles have already indicated that, over the last half century, there appeared a continuously increasing trend in the average temperature valueu pt o0 .5 °C. If this trend continues in the future, it is expected that in some areas of the world, there will appear extreme events such as excessive rainfall and consequent floods, droughts, and also local imbalances in the natural climatic be-

4 1 Energy and Climate Change havior giving rise to unusual local heat and cold. Such events will also affect the world food production rates. In addition, global temperatures could rise by a further 1– 3.5 °C by the end of the twenty-first century, which may lead potentially to dis- ruptive climate change in many places. By starting to manage the CO2 emissions through renewable energy sources now, it may be possible to limit the effects of climate change to adaptable levels. This will require adapting the world’s energy systems. Energy policy must help guarantee the future supply of energy and drive the necessary transition. International cooperation on the climate issue is a prerequisite for achieving cost-effective, fair, and sustainable solutions.

At present, the global energy challenge is to tackle the threat of climate change, to meet the rising demand for energy, and to safeguard security of energy supplies. Renewable energy and especially solar radiation are effective energy technologies that are ready for global deployment today on a scale that can help tackle climate change problems. Increase in the use of renewable energy reduces CO2 emissions, cuts local air pollution, creates high-value jobs, curbs growing dependence of one country on imports of fossil energy (which often come from politically unstable regions), and prevents society a being hostage to finite energy resources.

In addition to demand-side impacts, energy production is also likely to be affected by climate change. Except for the impacts of extreme weather events, research evidence is more limited than for energy consumption, but climate change could affect energy production and supply as a result of the following (Wilbanks et al., 2007):

1. If extreme weather events become more intense 2. If regions dependent on water supplies for hydropower and/or thermal power plant cooling face reductions in water supplies 3. If changed conditions affect facility siting decisions 4. If conditions change (positively or negatively) for biomass, wind power, or solar energyproductions

Climate change is likely to affect both energy use and energy production in many parts of the world. Some of the possible impacts are rather obvious. Where the climate warms due to climate change, less heating will be needed for industrial increase (Cartalis et al., 2001), with changes varying by region and by season. Net energy demand on a national scale, however, will be influenced by the structure of energy supply. The main source of energy for cooling is electricity, while coal, oil, gas, biomass, and electricity are used for space heating. Regions with substantial requirements for both cooling and heating could find that net annual electricity demands increase while demands for other heating energy sources decline (Hadley et al., 2006). Seasonal variation in total energy demand is also important. In some cases, due to infrastructure limitations, peak energy demand could go beyond the maximum capacity of the transmission systems. Tol (2002a,b) estimated the effects of climate change on the demand for global energy, extrapolating from a simple country-specific (UK) model that relates the energy used for heating or cooling to degree days, per capita income, and energy efficiency. According to Tol, by 2100 benefits (reduced heating) will be about 0.75% of gross domestic product

(Parte 1 de 8)