Harnessing sunlight

The key ingredient for new ways to harness sunlight is the solar cell, or photovoltaic (PV) cell, a device that absorbs photons from sunlight (or artificial sunlight) and generates an electrical current [9]. Figure 10.6 shows the evolution over time of photovoltaic cells since 1975 [4]. The first photovoltaic cell was a pn junction based on Si and had an efficiency of 5% to 6% [3] at present, Si pn junctions have overall power efficiencies of about 22% (maybe 10% in commerce) at the moment, Si solar cells are expensive but durable. 

We have recently noted (21) the attractive characteristics of the series, CuXPR3(N-N) (typically X = Cl, Br R = alkyl or phenyl, N-N = phen or bipy). Depending upon the lability of PR3, these compounds can conceivably function as either Class 1 or Class 3 sensitizers. Furthermore, their strong absorption in the visible wavelength region raises the possibility of harnessing sunlight to drive useful photochemical reactions. 

Joseph Priestly was one of the first to isolate oxygen. He achieved this using mercury oxide in 1774 by harnessing sunlight as an energy source. 

Radiant energy is one of the most abundant forms of energy available to mankind. Nature provides sunlight, the type of radiation that is essential for many forms of life and growth. There are some natural substances, which generate yet another kind of radiation that can be destructive to life, but when harnessed it can provide other forms of energy or serve in medicine or industrial applications. 

Energy Can Be Harnessed from Sunlight Solar energy is also released when we bum fossil fuels, which are the decayed remains of plants and plant-eating animals. 

There are two main ways to harness the power of the sun to generate electricity photovoltaic (PV), where sunlight is directly converted into electricity via solar cells, and solar-thermal power. PV is a proven technology that is most appropriate for small-scale applications to provide heat and power to individual houses and businesses. Sunlight falls on a layer of semiconductors, which jostles electrons. This, in turn, creates an electrical current that can be used as a source for heat. 

Life is also complex and the detailed chemistry of how the organic molecules which sustain and regulate life were formed is yet to be worked out. However, there was process in which simple molecules were synthesized to form complex polymers useful in the process of replication and the transmission of genetic information. Many believe that the nucleic add RNA was a precursor to the modem DNA and that life first developed in an RNA world. In addition the relevant energy sources were harnessed to facilitate life. Now these come mostly from sunlight, but in the early Earth they were probably chemical. 

A few years ago, or maybe you heard this recently because it has achieved urban legend status, a rumor you may have heard is that polar bear fur is actually like a fiber optic network for harnessing or focusing sunlight toward the bear s skin. While this would have been cool, it s unfortunately completely bogus. 

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