Process Description
A hydrogen fueled Proton exchange membrane fuel cell, for example, uses hydrogen gas (H2) and oxygen (O2) to produce electricity and water (H2O); a regenerative hydrogen fuel cell uses electricity and water to produce hydrogen and oxygen.
When the fuel cell is operated in regenerative mode, the anode for the electricity production mode(fuel cell mode) becomes the cathode in the hydrogen generation mode(reverse fuel cell mode), and vice versa. When an external voltage is applied, water at the cathode side will undergo electrolysis to form hydrogen and oxide ions; oxide ions will be transported through the electrolyte to anode where it can be oxidized to form oxygen. In this reverse mode, the polarity of the cell is opposite to that for the fuel cell mode. The following reactions describe the chemical process in the hydrogen generation mode:
At cathode: H2O + 2e- → H2 + O2-
At anode: O2- → 1/2O2 + 2e-
Overall: H2O → 1/2O2 + H2
Read more about this topic: Regenerative Fuel Cell
Famous quotes containing the words process and/or description:
“When you start with a portrait and search for a pure form, a clear volume, through successive eliminations, you arrive inevitably at the egg. Likewise, starting with the egg and following the same process in reverse, one finishes with the portrait.”
—Pablo Picasso (1881–1973)
“It [Egypt] has more wonders in it than any other country in the world and provides more works that defy description than any other place.”
—Herodotus (c. 484–424 B.C.)