Electric Energy Harvesting

ZnO nanocrystals demonstrate strong polarization, see Fig. 16.11 [105], which ensures nano-ZnO a material with dilute magnetism and catalytic active. Meanwhile, nano-ZnO exhibits piezoelectricity, which has been used for energy harvesting devices. Fig. 20.10 illustrates the fiber nanogenerator of electricity by 

Undercoordination induces global enttapment by subjective polarization depending on the electronic configuration of the outermost electron shell of the substance. 

The localization and polarization of the non-bonding electrons with nonzero spin are responsible for the dilute magnetism and conductor-insulator transition at the nanoscale. 

The dominance of entrapment or polarization creates the catalytic attributes of the otherwise inert noble metals at the nanoscale. 

The coupling of energy densification (solid like and high elasticity), quantum entrapment, and polarization dictates the interface 4S. 

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Because redox reactions can make electrons move from one substance to another it is possible to create a setup so that the electrical energy produced in a redox reaction can be channeled to do work. There is a way to harvest the electrons produced by a redox reaction. Today these devices are called batteries. The first device that could do this was called a voltaic cell. In a voltaic cell a redox reaction occurs spontaneously so that the electrons can be used to do work. A typical voltaic cell is shown in Figure 10.1. 

The input chemicals are carbon dioxide and water, while the output is oxygen and carbohydrates. The latter serve as a feedstock for other organic products such as wood, coal, oil, and gas constituting the World s fossil fuel reserves. It is estimated that about lO tons of carbon dioxide are assimilated annually by plants on Earth, whereby the amount of solar energy harvested by natural photosynthesis is 3 x 10 kJ, corresponding to the continuous generation of 90000 GW of electrical power. 

Sodano, H. A., Park, G., Inman, D. J. Estimation of electric charge output for piezoelectric energy harvesting, Strain, 40(2), 49-58 (2004). 

Solar cell efficiency is a most valuable measure of its performance. With sunlight impinging from the zenith on a sunny day, a surface perpendicular to the fight receives about 1 kW/m. When converted by a solar cell of 10 percent efficiency (presently reached or exceeded by most commercially available solar panels), this means that 100 W/m in electrical energy can be harvested. This is sufficient if surface areas are ample and the panels are relatively inexpensive. However, where surface areas are at a premium—e.g., on top of a solar car or in some satellites— it is essential to use more efficient solar cells. These are available from carefully engineered Si cells or from GaAs, reaching efficiencies close to 25 percent. 

Thus, in the first case - that of paper recycling - in evaluating the impacts, we must also take account of the production ofXMJ of electricity in the local conditions for conventional electricity production. In the second case - that of thermal energy harvesting - we also need to consider the conventional production of 7 kg of paper from wood, when evaluating the impacts. We can then perform a vahd comparison of two systems which have the same products 7 kg of paper andXMJ of electricity. 

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