Solar-Energy, Radu D. Rugescu

Solar-Energy, Radu D. Rugescu

(Parte 1 de 7)

Solar Energy Solar Energy

Solar Energy

Edited by Radu D. Rugescu

Intech

Published by Intech

Intech Olajnica 19/2, 32000 Vukovar, Croatia

Abstracting and non-profit use of the material is permitted with credit to the source. Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published articles. Publisher assumes no responsibility liability for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained inside. After this work has been published by the Intech, authors have the right to republish it, in whole or part, in any publication of which they are an author or editor, and the make other personal use of the work.

© 2010 Intech Free online edition of this book you can find under w.sciyo.com Additional copies can be obtained from: publication@sciyo.com

First published February 2010 Printed in India

Technical Editor: Teodora Smiljanic Cover designed by Dino Smrekar

Solar Energy, Edited by Radu D. Rugescu p. cm. ISBN 978-953-307-052-0

Preface

The present book on “Solar Energy” is entitled to reveal some of the latest concepts and research in the direct exploitation of solar energy and incorporates eighteen chapters, authored by fifty-two selected, international contributors. All these contributions are developed in the two of the areas that we believe to be the most promising and efficient in solar energy: the new generation of PV cells and the solar array-gravity draught accelerators. From new advances in the Material Science to provide high efficiency photocells, up to the airborne solar “chimney” and the closed-circuit chimney gravitational accelerator for use on Mars and Moon, the original authors explain the new concepts in a high-level, first-hand presentation, which characterizes the entire book. The chapters are designed to gradually attract the interest of the reader by means of their content. Despite the small space available, or rather surely due to this constraint, the stories of the new technologies are presented in a very synthetic and easy-to-read manner, a necessary quality for time saving today.

The present “Solar Energy” science book hopefully opens a series of other firsthand texts in new technologies with practical impact and subsequent interest. They might include the ecological combustion of fossil fuels, space technology in the benefit of local and remote communities, new trends in the development of secure Internet Communications on an interplanetary scale, new breakthroughs in the propulsion technology and others. The editors will be pleased to see that the present book is open to debate and they will wait for the readers’ reaction with great interest. Critics and proposals will be equally welcomed.

The editor addresses special thanks to the contributors for their high quality and courageous initiative, and to the Technical Corp. of editors that conveyed the text into a pleasant and cozy presentation.

Bucharest, January 18, 2010

Editor

Prof. Dr. Eng. Radu D. Rugescu

University Politehnica of Bucharest Romania E.U.

Contents

Preface V

1. Potential of the Solar Energy on Mars 001 Dragos Ronald Rugescu and Radu Dan Rugescu

2. Surface-Barrier Solar Cells Based On Monocrystalline Cadmium

Telluride with the Modified Boundary 025

P.М. Gorley, V.P. Makhniy, P.P. Horley, Yu.V. Vorobiev and J. González-Hernández

3. Control of a 3KW Polar-Axis Solar Power Platform with Nonlinear Measurements 043

John T. Agee and Adisa A. Jimoh

4. Silicon Solar Cells: Recombination and Electrical Parameters 069 Saïdou Madougou, Mohamadou Kaka and Gregoire Sissoko

5. Efficient Silicon Solar Cells Fabricated with a Low Cost Spray Technique 081

Oleksandr Malik and F. Javier De la Hidalga-W.

6. Efficiency of Thin-Film CdS/CdTe Solar Cells 105 Leonid Kosyachenko

7. Energy Control System of Solar Powered Wheelchair 131 Yoshihiko Takahashi, Syogo Matsuo, and Kei Kawakami

8. Uses of Concentrated Solar Energy in Materials Science 145 Gemma Herranz and Gloria P. Rodríguez

9. Solar Chimney Power Plants – Developments and Advancements 171 Marco Aurélio dos Santos Bernardes

10. Floating Solar Chimney Technology 187 Christos D. Papageorgiou

1. Organic Solar Cells Performances Improvement Induced by Interface Buffer Layers 223

J. C. Bernède, A. Godoy, L. Cattin, F. R. Diaz, M. Morsli and M. A. del Valle

12. New Trends in Designing Parabolic trough Solar Concentrators and Heat Storage Concrete Systems in Solar Power Plants 267

Valentina A. Salomoni, Carmelo E. Majorana, Giuseppe M. Giannuzzi, Adio Miliozzi and Daniele Nicolini

13. Charge Carrier Recombination in Bulk Heterojunction Organic Solar Cells 293

Gytis Juška and Kęstutis Arlauskas

14. Numerical Simulation of Solar Cells and Solar Cell Characterization

Methods: the Open-Source on Demand Program AFORS-HET 319

Rolf Stangl, Caspar Leendertz and Jan Haschke

15. Amorphous Silicon Carbide Photoelectrode for Hydrogen Production from Water using Sunlight 353

Feng Zhu, Jian Hu, Ilvydas Matulionis, Todd Deutsch, Nicolas Gaillard, Eric Miller, and Arun Madan

16. Contact Definition in Industrial Silicon Solar Cells 375 Dr. Luis Jaime Caballero

17. Aerostat for Solar Power Generation 399 G. S. Aglietti, S. Redi, A. R. Tatnall, T. Markvart and S.J.I. Walker

18. Photon Management in Dye Sensitized Solar Cells 413 Silvia Colodrero, Mauricio E. Calvo and Hernán Míguez

Potential of the Solar Energy on Mars

Dragos Ronald Rugescu1 and Radu Dan Rugescu2 1University of California at Davis, 2University Politehnica of Bucharest 1U.S.A., 2Romania E.U.

1. Introduction

The problem of energy accessibility and production on Mars is one of the three main challenges for the upcoming colonisation of the red planet. The energetic potential on its turn is mainly dependent on the astrophysical characteristics of the planet. A short insight into the Mars environment is thus the compulsory introduction to the problem of energy on Mars. The present knowledge of the Martian environment is the result of more than two centuries of attentive observation on its astronomical appearance and, more recently, on its on-site astrophysical features. Recent surface measurements of Martian geology, meteorology and climate had fixed the sometime-unexpected image of a completely desert planet. Mars is one of the most visible of the seven planets within the solar system and thusfor its discovery cannot be dated, still the interest for Mars is old. It was easily observed from the ancient times by necked eye and the peculiar reddish glance of the planet had induced the common connection of the poor planet with the concept of war. The god of war and the planet that inherited his name had provoked, still from antiquity, curiosity and disputes on the most diverse themes. These disputes are at a maximum right now regarding the habitability of Mars. The red planet owes his color to still unexplained causes, where a yet undisclosed chemistry of iron oxides seems to be the main actor. The visit card of Mars is fast increasing in the quantity of data and is now quite well known (Bizony, 1998), as we observe from the description that follows.

1.1 Mars as seen before the space age As far as the knowledge of the solar system has gradually extended, from optical, ground- based observations to the present astrophysical research on site, Mars appears as the fourth planet as starting from the Sun. The reddish planet of the skies, nicely visible by necked eyes, has attracted the most numerous comments during the time regarding the presence of life on an extraterrestrial planet. With all other eight planets, except for Pluto-Charon doublet, Mars aligns to a strange rule by orbiting the Sun at a distance that approximates a multiple of 2 from that of the Earth. This means that the rough 149.6 mil km of the Earthsemi-major axis is followed by a rough 212 mil km for Mars. In fact there are 227.92 mil

Solar Energy

Planet n Titius-Bode rule Actual semi-major axis

Mercury Venus Earth Mars

Asteroids Jupiter Saturn Uranus

Neptune/Pluto Sedna

0.4 0.7 1.0 1.6 2.8 5.2 10.0 19.6 38.8 7.2

0.39 0.72 1.0 1.52 2.80 5.20 9.54 19.20 30.10/39.20 75.0

Table 1. Mars within Titius-Bode’s rule (astronomical units)

It is immediately seen that the primary solar radiation flux is roughly two times smaller for Mars than it is for Earth. More precisely, this ratio is equal to 2.32. This observation for long has suggested that the climate on Mars is much colder than the one on Earth. This has not removed however the belief that the red planet could be inhabited by a superior civilization. Nevertheless, beginning with some over-optimistic allegations of Nicolas Camille Flammarion (Flamarion, 1862) and other disciples of the 19-th century, the planet Mars was for a century considered as presenting a sort of life, at least microbial if not superior at all. The rumor of Mars channels is still impressing human imagination. When estimates begun to appear regarding the Martian atmosphere and figures like 50 mbar or 20 mbar for the air pressure on Martian ground were advanced (Jones 2008), a reluctant wave of disapproval has been produced. It was like everybody was hoping that Mars is a habitable planet, that we have brothers on other celestial bodies and the humankind is no more alone in the Universe. As more data were accumulating from spectroscopic observations, any line of emission or absorption on Mars surface was immediately related to possible existence of biological effects. Even during the middle 20-th century the same manner was still preserving. In their book on “Life in the Universe” Oparin and Fesenkov are describing Mars in 1956 as still a potential place for biological manifestations (Oparin & Fesenkov, 1956). The following two excerpts from that book are relevant, regarding the claimed channels and biological life on Mars: “...up to present no unanimous opinion about their nature is formed, although nobody questions that they represent real formations on the planet (Mars)...” and at the end of the book “On Mars, the necessary conditions for the appearance and the development of life were always harsher than on Earth. It is out of question that on this planet no type of superior form of vegetal or animal life could exist. However, it is possible for life, in inferior forms, to exist there, although it does not manifest at a cosmic scale.”

1 In 1768, Johann Elert Bode (1747-1826), director of Berlin Astronomical Observatory, published his popular book, "Anleitung zur Kenntnis des gestirnten Himmels" (Instruction for the Knowledge of the Starry Heavens), printed in a number of editions. He stressed an empirical law on planetary distances, originally found by J.D. Titius (1729-96), now called "Titius-Bode Law".

Potential of the Solar Energy on Mars

The era of great Mars Expectations, regarding extraterrestrial life, took in fact its apogee in 1938, when the radio broadcast of Howard Koch, pretending to imaginary fly the coverage of Martian invasion of Earth, had produced a well-known shock around US, with cases of extreme desperation among ordinary people. Still soon thereafter, this sufficed to induce a reversed tendency, towards a gradual diminution of the belief into extraterrestrial intelligence and into a Martian one in particular. This tendency was powered by the fact that no proofs were added in support of any biological evidence for Mars, despite the continuous progress of distant investigations. Still every of the 36 great oppositions of Mars, since the “canali” were considered by Giovanni Schiaparelli in 1877, prior to the space age in 1957, like the series in 1901, 1911, 1941, 1956 was only adding subjective dissemination of channels reports, with no other support for the idea that on Mars any form of biological life exists. After Schiaparelli and Flammarion, the subjective belief in a Martian life is successively claimed by the well known astronomers Antoniadi, Percival Lowel, A. Dollfus, G. A. Tihov and others.

Any documentation of a hostile environment on Mars was received with adversity. Despite later spectroscopic and radiometric measurements from Earth, which were revealing a very thin atmosphere and extreme low temperatures, still in the immediate down of the space age the pressure on the Martian soil was yet evaluated at 87 mbar (Oparin & Fesenkov, 1956), overrating by more than ten times the actual value, irrefutably found after 1964. It is a pregnant evidence of how subjective the world could be in administrating even the most credible scientific data in this delicate subject. A piece of this perception is surviving even today.

1.2 Mars during the space age With the availability of a huge space carrier, in fact a German concept of Görtrupp, the

Soviets started to built a Mars spacecraft during 1959, along to the manned spacecraft Vostok. The launch took place as early as in October 1960, mere 3 years after Sputnik-1, but proved that only mechanical support is of no much use. The restart of the accelerator stage from orbit was a failure that repeated a few weeks later with similar non-results. The boost towards Mars commenced again with Mars-1 and a companion during the 1962 window, ending in failure again. It followed this way that a much smaller but smarter US device, called Mariner-4, despite of the nose-hood miss-separation of its companion Mariner-3, had marked the history of Mars in 1964 with a shaking fly-by of the planet and several crucial observations. These stroke like a thunder: the radio occultation experiment was suddenly revealing an unexpectedly low atmospheric pressure on Mars of approximately 5 mbar, much far below the most of the previous expectations. The life on Mars was bluntly threatened to became a childish story. Primitive but breathtaking images from Mariner-4 were also showing a surface more similar to the Moon’s one than any previous expectation could predict. A large number of craters were mixed with dunes and shallow crevasses to form a desert landscape and this appearance produced a change in the perception of the formation of the solar system at large. No channel was revealed and none of the previously mentioned geometrical marks on the Martian surface. The wave of disappointment grew rapidly into a much productive bolster for deepening these investigations, so incredible those results were. Mars’s exploration proceeded with Mariner-6 and 7 that performed additional Martian fly-byes in 1967 only to confirm the portrait of a fully deserted planet.

Solar Energy

The present hostile environment on Mars and the absence of life seem for now entirely proven, but it still remains to understand when this transform took place, whether there was sometime a more favorable environment on Mars and all issues regarding the past of Mars. We say for now because our human nature bolsters us towards an ideal which we only dream of, but which, as we shall prove, is almost accomplishable to the level of present technologies. Anyhow, the nephews of our nephews will perhaps take it up to the end. We are speaking of Mars’s colonization, process that could only take place after the complete transformation of the surface and of the atmosphere to closely resemble those on Earth, process we call terraforming. Whether planet Mars worth more than its terraforming, then it deserves all the money spent with this process. For the moment however, the Martian environment is far of being earth-like, as the compared data from the next table reveal (Almanac 2010):

(Parte 1 de 7)

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