Editing Hall–Héroult process (section)

===Anode effect===
The anode effect is a situation where too many gas bubbles form at the bottom of the anode and join, forming a layer. This increases the resistance of the cell, because smaller areas of the electrolyte touch the anode. These areas of the electrolyte and anode heat up when the density of the electric current of the cell focuses to go through only them. This heats up the gas layer and causes it to expand, thus further reducing the surface area where electrolyte and anode are in contact with each other. The anode effect decreases the energy-efficiency and the aluminium production of the cell. It also induces the formation of [[tetrafluoromethane]] (CF<sub>4</sub>) in significant quantities, increases formation of CO and, to a lesser extent, also causes the formation of [[hexafluoroethane]] (C<sub>2</sub>F<sub>6</sub>). CF<sub>4</sub> and C<sub>2</sub>F<sub>6</sub> are not [[Chlorofluorocarbon|CFCs]], and, although not detrimental to the [[ozone layer]], are still potent [[greenhouse gas]]es. The anode effect is mainly a problem in Söderberg technology cells, not in prebaked.<ref name="georg" />