Solar energy history

The first needs little justification to a group concerned with biomass, which is all derived from photosynthesis, the most successful of all solar energy methods throughout our history. Suffice it to say that whether our eventual target is photosynthesis in vitro, or improved photosynthesis in vivo, we need to know as much as possible about the mechanism of the natural process. 

H. Spanggaard, F.C. Krebs, A brief history of the development of organic and polymeric photovoltaics, Solar Energy Materials and Solar Cells 83 (2004) 125-146. 

The Earth s elliptical orbit causes the distance between the Earth and the Sun (the Earth s radius vector) to vary by 3.39% from perihelion (closest) to aphelion (farthest). These variations in distance cause the intensity of solar radiation at the top of the atmosphere to vary as 1/R2, where R is the radius vector. Thus the solar input at the top of the atmosphere varies from 1414 Wm 2 (in December) to 1321 Wm 2 (in July). Additional variations in solar intensity, or brightness, result from the solar sunspot cycle, and even solar oscillations. These slight variations in the solar output are usually accounted for in the calculation of solar energy available at the top of the atmosphere, or the total extraterrestrial solar radiation, referred to as ETR. The ETR has only been monitored from space since the early 1970 s, or almost three solar sunspot cycles. Excellent histories of ETR measurements and analysis are provided in Frohlich3 and Gueymard.4... 

The sensitization of electrodes to visible light by dye molecules is an old area of science with a rich history [2]. A dye-sensitized photoefifect was measured at a semiconductor surface as early as 1887 in Vienna [3]. The accepted mechanisms for the dye sensitization of electrodes emerged from photoelectrochemical studies in the 1960s and 1970s [4-6]. These studies were motivated by a desire to quantify interfacial electron transfer processes and develop cells useful for solar energy conversion. The two most common approaches are shown schematically in Figure 1. 

L The principle of the qmntitative invariability of life is a direct consequence of the statement that the biosphere is a product and transmitter of solar energy. Vernadsky uses this principle in all his significant works. One of the earliest references to this principle can be found in the notation [ On the constancy of hving matter ] (1908) The quantity of living matter is constant during the whole period of geological history that can be explored (Sytnik et all., 1988, p. 256). 

The largest research project in the history of solar energy is targeted towards the creation of very high efficiency solar cells with reasonable manufacturing costs and efficiencies in excess of 50%. The project is being led by the University of Delaware with snpport from the US Defense Advanced Advanced Research Projects Agency. 

Electrochemistry is the study of mutual transformation of chemical and elec-frical energy. Specifically, it deals with chemical reactions driven by an electric current and with the electricity produced by chemical reactions. Examples of electrochemistry are electroplating, iron oxidation (rusting), solar-energy conversion, electrochemical conversions (fuel cells, bafferies), phofosynfhe-sis, and respiration. In this chapter, the principles of electrochemisfry are reviewed. First, let us briefly look info fhe history of electrochemisfry. 

Winter feared that the point of transition to hydrogen and solar energy could be another "lost moment of history" [191. Timely transition to these clean forms of energy would lead toward new direction in development of human civilization, qualitatively and quantitatively different than the path based on utilization of fossil fuels. 

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