Biological Sciences
Solar Energy and Life on Earth
Solar energy is essential for life on Earth as it drives photosynthesis, the process by which plants convert sunlight into chemical energy. This energy is then transferred through the food chain, sustaining all living organisms. Solar energy also influences climate patterns and is a key factor in maintaining the planet's overall ecological balance.
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7 Key excerpts on "Solar Energy and Life on Earth"
eBook - PDFEvolution on Planet Earth
Impact of the Physical Environment
- Lynn Rothschild, Adrian Lister(Authors)
- 2003(Publication Date)
- Academic Press(Publisher)
The solar radiation flux that organisms are exposed to changes diurnally, seasonally, during its life cycle, and most likely during geological time. For these reasons, solar radiation has provided an evolu-tionary opportunity as well as a challenge to life on Earth. In this chapter I explore the per-vasive role of the Sun on biotic evolution, with an emphasis on the role of solar radiation. Evolution on Planet Earth Copyright # 2003 Elsevier ISBN 0-12-598655-6 All rights of reproduction in any form reserved ABSTRACT See Plates 10-12 The Sun is vital for life on Earth, its physiology, ecology and evolution. Its energy influences climate, and is used as the ultimate source of energy for nearly all life. The direct influence of the Sun on individual organisms and metabolic processes depends on the spectral nature of the radiation used, its total flux and the timing of exposure. All of these parameters have changed over geological time, and radiation received by any given organism also varies daily, seasonally and annually. In this chapter, the evolutionary impact of solar radiation is examined from the perspective of different spectral ranges, including UV radiation, visible radiation, and infrared radiation. The Sun is instrumental in prebiotic chemistry, the physical, chemical and then biogeochemistry of the Earth. It is been both a vital resource during the course of evolution, as well as a hazardous substance. Some day we must move beyond the immediate influence of our star or be consumed by it, but we will always bear the unmistakable imprint of the Sun. 6.2 The Sun: vital facts The Sun is a 4.6 10 9 -year-old main sequence star, worshipped by the Greeks as the young god Helios, and by the Romans as the god Sol. The Sun was born by the accretion of the pro-tostellar core, covered by a cloud of dust (Canuto et al ., 1983). The protostellar Sun would have emitted primarily infrared radia-tion.
eBook - PDFFuture Sources of Organic Raw Materials: CHEMRAWN I
CHEMRAWN Chemical Research Applied to Words Needs
- L.E. St-Pierre, G. R. Brown(Authors)
- 2017(Publication Date)
- Pergamon(Publisher)
Solar energy use through biology—past and future D . O. H A L L University of London King's College, 68 Half Moon Lane, London SE24 9JE, U.K. I N T R O D U C T I O N (refs. 1 -7) T H E R E A R E not many people nowadays who need reminding that our fossil carbon reserves— whether for fuel or chemicals—are the products of past photosynthesis. Photosynthesis is the key process in life and as developed by plants can be simply represented as Η 2 θ + C 0 2 s o , a P r a e n ner 8 y > organic materials + 0 2 In addition to C, Η and O, plants also incorporate nitrogen and sulphur into the organic material via light-dependent reactions—this latter point is often not sufficiently recognized. Thus the basic processes of photosynthesis have determined life as we know it (dependent on organic materials and oxygen) and will continue to play the major role in the integration of bioenergetic systems in the future. In the past photosynthesis has given us coal, oil and gas, fuelwood, food, fibre and chemicals. The relative use of these fixed carbon sources has varied over the years and will undoubtedly do so in the future. It seems necessary now to look at how photosynthesis fits into the biosphere and how we could possibly use biological solar energy conversion in the future as a source of raw materials. Each year plant photosynthesis fixes about 2 x 10 11 tonnes of carbon with an energy content of 3 x 10 21 J; this is about 10x the world's annual energy use and 200x our food-energy consumption, even though the photosynthetic process is operating at only a 0 . 1 % efficiency (total incoming radiation on earth's surface over whole year). The efficiency on land may be about 0.2-0.3% overall, whereas average agriculture may be about 0.5% efficient (see later). It should be realized early on that these efficiencies represent stored energy and not just the initial conversion efficiencies so often quoted in other energy systems.
eBook - PDF- James Petersen, Dorothy Sack, Robert Gabler, , James Petersen, James Petersen, Dorothy Sack, Robert Gabler(Authors)
- 2021(Publication Date)
- Cengage Learning EMEA(Publisher)
All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. C H A P T E R 3 • S O L A R E N E R G Y A N D E A R T H – S U N R E L A T I O N S H I P S 64 stone-like or metallic bodies that melt and burn when encounter- ing oxygen and friction with Earth’s atmosphere, appearing as streaks of light, or “shooting stars.” A meteor that survives a fall through the atmosphere and strikes Earth’s surface is called a meteorite (● Fig. 3.4). 3-2 The Earth–Sun System Earth receives only about one two-billionth (1/2,000,000,000) of the radiation given off by the sun, but even this tiny fraction of the sun’s energy is enough to drive the biological and physical characteristics of Earth’s surface. The amount of solar energy that reaches Earth every hour far exceeds the energy consumption by all human activities in a year. Solar energy is the most important factor in determining environmental conditions on Earth. Except for geothermal heat sources (such as volcanic activity, geysers, and hot springs) and heat emitted by decaying radioactive miner- als, the sun remains the energy source for Earth’s atmospheric, oceanic, and biological systems. Our planet’s size, its distance from the sun, its atmospheric and surface characteristics, its annual orbit around the sun, and its daily rotation all affect the amount of solar radiation that Earth receives. Although some processes that support Earth’s environments result from internal forces unrelated to the sun, these processes would have little relevance were it not for life- sustaining solar energy.
- F I Woodward, J E Sheehy(Authors)
- 2017(Publication Date)
- Butterworth-Heinemann(Publisher)
The food chains of the world are all based on these photosynthetic products, which have been estimated to provide 3 x 10 21 J of energy annually or 2 x 10 11 tonnes of carbon (Hall and Rao, 1977). The waveband and energy content of solar radiation have been effective constraints in the evolution of photo-biological processes. The majority of these processes have action spectra limited to the 0.3-0.95 μπι waveband (Figure 1.1) and the effectiveness of solar radiation in these processes is determined by the quantum energy content and the flux density of radiation in the wave-band. Photosynthesis is an important example of a biochemical process which can only be driven by the high energy content of solar radiation. It is powered by radiation in the 0.35-0.95 μπι waveband (including bacterial). The production of carbohydrates from carbon dioxide and water requires an energy input of 477 kJ for every mole of carbon dioxide fixed. This is supplied by photo-synthetically active radiation (PAR) at an average 1 2 2000 h E CM Έ 1500 h 1000 h öi 500 h v_^--ω Q. 0.2 0.5 1.0 Wavelength (μΐη) 1.5 ' f 2.0 Action spectra for photobiological responses (μνη) Photosynthesis (1) ι Photomorphogenesis and phototaxis in plants (2) | Human vision (3) Insect vision (4) Insect photoperiodism (5) | Insect phototaxis (6) Haemolysis (7) Erythema (3) h Vitamin D production (7) l·-Skin cancer (8) r-DNA absorption r Melanin oxidation (3) Photosensitization of skin by phototoxic substances (10) Hyperaemia (3) Pit-organ sensitivity (4) I Figure 1.1 Spectral distribution of solar radiation and action spectra of photobiological responses. Data for spectral distribution from Koller (1965) and Szeicz (1974). Data for photobiological responses from: 1, Hall and Rao (1 977); 2, Mohr (1 972); 3, Koller (1 965); 4. Ricklefs (1 973); 5. Goldsmith (1973); 6, Dethier (1963); 7, Robinson (1966); 8, Epstein (1970); 9, Caldwell (1971); 10.
eBook - PDF- Anco S. Blazev(Author)
- 2021(Publication Date)
- River Publishers(Publisher)
SUNLIGHT BASICS AND KEY CONCEPTS Life on Earth depends on the sun’s energy. The sun is a large star at the center of our solar system and is approxi-mately 93 million miles away, but its life-giving energy arrives on Earth every day. This exact distance between the sun and the Earth is crucial to maintaining life. The Earth’s orbit and its very appropriate distance from the sun are responsible for providing climate conducive to life which exists here. The other planets are either too close (thus too hot), or too far away (and too cold) to sustain organic life as we know it. The Earth also has an appropriate atmosphere with enough oxygen, carbon dioxide, and water to sustain life. All life-sustaining elements are in the right propor-tion, form and shape needed for life to flourish on Earth. These are also in a very delicate balance, so changes or modifications to this balance are detrimental to life on Earth. Sunlight essentially consists of a range of energy bands, which we generally refer to as the solar spectrum. We can see some of these bands, but most are invisible to the human eye. We can also feel some of these when they impact our skin and are perceived as heat. So, sunlight is radiation of the electromagnetic type, with what we see and feel being only a small part of its entire spectrum. From our perspective, we think of visible light as the most important component of the solar spectrum, because we can see it. The infrared part of the solar spectrum is also noticeable since we feel it as heat. However, these are just small parts of the entire light (sunlight) spectrum, and they are clearly distinguished by their different wavelengths and respective properties.
eBook - PDF- R.A. Bailey(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
11 PHOTOCHEMISTRY IN THE BIOSPHERE 11.1 INTRODUCTION Conventional fossil fuels (coal, oil, and gas) represent stored, concentrated energy produced photochemically and biologically eons ago and preserved in a convenient transport-able form for present-day usage. We have seen in Chapter 2, however, that although at the present time these fuels account for most of the energy used in the U.S., they are nonreplen-ishable sources and are of limited amount. It was also pointed out in Chapter 2 that solar energy is the most abund-ant, continuously replenished form of energy available on earth. It therefore must be considered a serious contender in our search for viable energy sources even though at the present time solar power generation does not appear to be an economically feasible alternative to other means such as nuclear fission. It is the purpose of this chapter to con-sider radiation from the sun as a source of energy through artificial and natural photochemical processes occuring in the biosphere. 11.2 ARTIFICIAL PHOTOCHEMICAL STORAGE OF SOLAR ENERGY 11.2.1 Energy Conversion and Storage In Section 2.5.2, several physical methods of solar energy utilization were described in which the energy is col-lected and stored as heat. The conversion efficiency for these thermal uses of solar energy is subject to the basic limitation of the second law of thermodynamics expressed mathematically in Eq. (2.9a). This states that if a quantity of heat is extracted from a reservoir at temperature T^, then only part of this can be converted into an amount of work; 280 11 . PHOTOCHEMISTRY IN THE BIOSPHERE 281 the remainder of the heat must pass in the same cyclic opera-tion into a reservoir at a lower temperation T 2 . On the other hand, photochemical utilization of sunlight involves the direct usage of light in photochemical reactions to pro-duce useful products in the form of stored fuels, etc.; a temperature gradient is not required, and the second law restriction no longer applies.
eBook - ePub- Hans-Walter Heldt, Birgit Piechulla(Authors)
- 2010(Publication Date)
- Academic Press(Publisher)
2 The use of energy from sunlight by photosynthesis is the basis of life on earthPlants and cyanobacteria capture the light of the sun and utilize its energy to synthesize organic compounds from inorganic substances such as CO2 , nitrate, and sulfate to synthesize their cellular material; they are photoautotrophic. In photosynthesis photon energy splits water into oxygen and hydrogen, the latter bound as NADPH. This process, termed the light reaction , takes place in the photosynthetic reaction centers embedded in membranes. It involves the transport of electrons, which is coupled to the synthesis of ATP. NADPH and ATP are consumed in a so-called dark reaction to synthesize carbohydrates from CO2 (Fig. 2.1 ). The photosynthesis of plants and cyanobacteria created the biomass on earth, including the deposits of fossil fuels and atmospheric oxygen. Animals are dependent on the supply of carbohydrates and other organic compounds as food; they are heterotrophic. They generate the energy required for their life processes by oxidizing the biomass, which has first been produced by plants. When oxygen is consumed, CO2 is formed. Thus light energy captured by plants is the source of energy for the life processes of animals.Figure 2.1 Life on earth involves a CO2 cycle.2.1 How did photosynthesis start?Measurements of the distribution of radioisotopes led to the conclusion that the earth was formed about 4.6 billion years ago. The earliest indicators of life on earth are fossils of bacteria-like structures, estimated to be 3.5 billion years old. There was no oxygen in the atmosphere when life on earth commenced. This is concluded from the fact that in very early sediment rocks iron is present as Fe2+ . Mineral iron is oxidized to Fe3+
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