Generating Electrical Power with Fuel Cells

We now transform the silicon chlorides back into elemental silicon. For this we use the Siemans process  

So we add units to our flowsheet to isolate SiHCls and react with hydrogen to form silicon  

The silicon from this process is used to grow large Si crystals, called ingots or boules, typically six to twelve inches in diameter and over a meter long. The Si boule is sliced into wafers, which in turn are used to produce integrated circuits, also known as chips. 

Chemical engineering is integral to the semiconductor industry. Andrew Grove, CEO of Intel and Time magazine s 1997 Man of the Year, earned a BS degree in chemical engineering from CCNY in 1960. 

6 Generating Electrical Power with Fuel Cells 

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In the space exploration program, large quantities of liquid hydrogen have been used both as a fuel for generating electric power in fuel cells, and as a rocket fuel with oxygen or fluorine as the oxidizer. 

Fuel cells such as the one shown on Fig. 3.4a convert H2 to H20 and produce electrical power with no intermediate combustion cycle. Thus their thermodynamic efficiency compares favorably with thermal power generation which is limited by Carnot-type constraints. One important advantage of solid electrolyte fuel cells is that, due to their high operating temperature (typically 700° to 1100°C), they offer the possibility of "internal reforming" which permits the use of fuels such as methane without a separate external reformer.33 36... 

Hyundai introduced its new i-Blue Fuel Cell Electric Vehicle. The i-Blue platform incorporates Hyundai s third-generation fuel cell technology and is powered by a 100-kW electrical engine and fuel cell stack. It is fueled with compressed hydrogen at 700 bar stored in a 115 liter tank. The i-Blue is capable of running more than 600-km per refueling stop and has a maximum speed of 165-km/h. 

Figure 1 shows the schematic of a PEM fuel cell where there is an H2/02 front dividing the cell into two portions one is H2-rich and generates electric power as a power source, and the other is H2-ffee and becomes a load driven by the power source. The existence of the H2/02 front results from two scenarios (a) start-stop events frequently seen in automotive application and (b) local H2 starvation caused by local blockage of the H2 fuel supply, e.g., part of anode flow-field is filled with liquid water. As shown in Fig. 1,... 

In some urban areas, there are air quality and other restrictions that have made it difficult to build new generation facilities. Solid oxide fuel cells (SOFCs) may be a better technology for power generation with their higher electric efficiency and more usable heat. They do not need an external reformer. 

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