Biofuel principle

Besides the broad applications of electrically contacted enzyme electrodes as amperometric biosensors, substantial recent research efforts are directed to the integration of these functional electrodes as biofuel cell devices. The biofuel cell consists of an electrically contacted enzyme electrode acting as anode, where the oxidation of the fuel occurs, and an electrically wired cathode, where the biocatalyzed reduction of the oxidizer proceeds (Fig. 12.4a). The biocatalytic transformations occurring at the anode and the cathode lead to the oxidation of the fuel substrate and the reduction of the oxidizer, with the concomitant generation of a current through the external circuit. Such biofuel cells can, in principle, transform chemical energy stored in biomass into electrical energy. Also, the use... 

We examine some common principles of green chemistry in Section 16.2. Raw materials including recycling are discussed in Sections 16.3, and 16.4 reviews biomass conversion technologies. Sections 16.5 through 16.7 discuss the sense and nonsense of green chemistry and biofuels from various perspectives. 

Another interesting attempt worth noting is the combination of porphyrin sensitized solar cell with a fuel cell made by Moore and Gust. The hybrid cell can realize an open circuit voltage of 1.2 V. The energy conversion efficiency of this photoelectrochemical biofuel cell can, in principle, produce more power than either a photoelectrochemical cell or a biofuel cell working individually [83],... 

Because triacylglycerols release heat on combustion, they can in principle be used as fuels for vehicles. In fact, coconut oil was used as a fuel during both World War I and World War II, when gasoline and diesel supplies ran short. Since coconut oil is more viscous than petroleum products and freezes at 24 °C, engines must be modified to use it and it can t be used in cold climates. Nonetheless, a limited number of trucks and boats can now use vegetable oils, sometimes blended with diesel, as a fuel source. When the price of crude oil is high, the use of these biofuels becomes economically attractive. 

In conclusion, biofuel cells have a tremendous potential to be applied in, for example, implantable sensors or similar functional devices. They are a striking example of the continued development and application of the principles of biosensors employing direct ET. 

As we have attempted to lessen our dependence on fossil fuels, the demand for biofuels, such as ethanol, which is produced by the fermentation of the sugars found in corn, has increased. Using Le Chatelier s principle, predict which way the equilibrium will shift during the fermentation of sugar for each of the fol lowing changes. 

Biofuels and peat can be dried according to different thermodynamic principles. The most common method is the use of flue gases. Another is the use of superheated steam. Finally, double-effect drying will be discussed. 

The most widely use of biomass is the provision of heat released during combustion of solid biofuels. But combustion is only one conversion process among others based on a heat-induced chemical conversion of the organic material. Therefore within the following explanations we first discuss the basics of such thermo-chemical conversion processes. Then we focus on the technical implementation of these principles in conversion plants. 

Principles of Biofuel Cell Functioning Mediated or Direct Electron Transfer... 

By adjusting the composition of the anode s and cathode s supporting electrolytes, the iiFl-FC principle makes it possible to use a large variety of inexpensive nonplatinum catalysts in fuel cells. For example, (jFl-FCs that operate at room temperature and can use neutral (pH 7) supporting electrolytes are quite well suited as biofuel cells, with different enzymes as catalysts. 

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