Energy sources electrolysis cells

The negative value of the cell potential, 8° gn, shows that the system requires an external energy source to occur. That is, the reaction is an electrolysis reaction. 

These fuels (pure H2, H2/C02, and H2/C0/C02) can also be produced from renewable energy sources—biomass, solar, windmills, and hydroelectric power. On the other hand, pure H2 can be generated by water electrolysis using nuclear power plants. Hydrogen is the most electro-reactive fuel for fuel cells operating at low and intermediate temperatures. 

The expression cell reaction is used almost exclusively for the spontaneous reactions occurring in galvanic cells [i-iv]. However, also in electrolysis cells (- electrochemical cells) chemical transformations take place, when current is passed through the cell from an external source. Evidently, we may also speak of cell reactions even in this case, albeit additional energy is needed for the reaction to proceed since AG > 0. 

A commercial solar cell (model BL-432, Showa Shell Petroleum Co.) was used as the energy source for electrolysis. The maximum output of power of this solar cell was 8 W, and the open-circuit voltage 20 V. A given voltage for electrolysis was obtained through a variable resistance. 

Fig. 1 Schematic representation of the electrolysis system using a solar cell as the energy source.

The prolonged electrolysis of COj was carried out on the functional dual-film electrode with a solar cell as the energy source. The results obtained are shown in Table 1 where... 

First, in this scenario solar or wind power-operated water electrolyzers are included. These energy sources deliver their power discontinuously. So, the electrolyzers must be able to tolerate fluctuating loads, a goal to be achieved in present developments. Second, this economy includes the conversion of electricity to hydrogen by electrolysis and from hydrogen back to electricity via fuel cells. So, the efficiency of this sequence has to be taken into account when looking at the chances. 

In an electrolytic cell, an external energy source makes a nonspontaneous redox reaction (AG > 0) occur. In electrolysis of a molten binary ionic compound (salt), the cation is reduced to the metal and the anion is oxidized to the nonmetal. For an aqueous salt solution, the products depend on whether water or one of the ions of the salt requires less energy to be reduced or oxidized. 

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