A chemical energy storage system operates on the principle of converting electrical energy into chemical energy through a reversible chemical process, and then converting the stored chemical energy back into electrical energy or usable energy when required. The process typically begins with electricity supplied from renewable sources like solar, wind, or hydro, which is used to split water molecules into hydrogen and oxygen through electrolysis. Electrolysis is a key step in chemical energy storage systems, especially in hydrogen-based storage, where an electrolyzer serves as the central device. The electrolyzer contains electrodes immersed in water, and when an electric current is applied, water molecules (H₂O) are split into hydrogen (H₂) and oxygen (O₂) gases. This process stores the electrical energy in the form of chemical bonds in hydrogen molecules. The oxygen can be released into the atmosphere or collected for industrial use, while hydrogen is stored under pressure in tanks or other storage mediums such as metal hydrides or chemical carriers. Once the hydrogen is stored, it represents potential energy that can be converted back to electricity or other useful energy forms. One common method of energy conversion from chemical storage is using a fuel cell. In a fuel cell, hydrogen reacts with oxygen in an electrochemical reaction to produce electricity, heat, and water. The chemical energy of hydrogen is thus converted back into electrical energy without combustion, which ensures high efficiency and low emissions. In the fuel cell, hydrogen molecules are split into protons and electrons at the anode. The electrons travel through an external circuit, producing electric current, while the protons move through an electrolyte to the cathode, where they combine with oxygen and