The electrochemical cell with solids as electrodes, as in Fig. 10.2a, operates as a battery. That is, it produces current until one of the reactants is exhausted. The cell needs to be charged by operating in the electrolysis mode, as in Fig. 10.2b.
If the active constituents of the two half-cells are gaseous, however, continuous operation is possible. The preceding example dealt with a cell with one gaseous electrode and one solid electrode. In this section, a cell fueled only by gas flows is analyzed. Electrochemical cells fed by external reactant sources are called fuel cells.
The simplest fuel cell is one that combines hydrogen and oxygen to produce only water as a waste product. A schematic of such a cell is shown in Fig. 10.3. The overall cell reaction is:
The unit is operated at room temperature, which permits an aqueous solution to be used as the
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Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.