Introduction to Electrolyzers and Fuel Cells
Electrolyzers are devices that use an electric current to provide the energy that splits a water molecule (H2O) into hydrogen (H2) and oxygen (O2). Electrolyzers have a positive and negative side, like a magnet or a battery. Hydrogen gas is generated on the negative side while oxygen gas is generated on the positive (Figure 1). If we attach empty tubes or cylinders to either side, we can collect these gases and use them in experiments.
Our electrolyzer is called a proton exchange membrane (PEM) electrolyzer, which can work as an electrolyzer when we connect it to an electric current, but can also work in reverse and provide power as a hydrogen fuel cell. When hydrogen is present and we connect an electric motor to the cell instead of a battery or solar cell (Figure 2), the fuel cell generates electricity through the wires and provides electric power to the motor. While the fuel cell is running, hydrogen and oxygen are combined again to produce water, which is the only waste product of a hydrogen fuel cell.
For a detailed look at the chemical reactions involved in our PEM electrolyzer, read The PEM Electrolyzer/Fuel Cell.