Electrolysis uses electricity as its energy source. Specifically, it requires a direct electric current (DC electricity) to drive the non-spontaneous chemical reaction that splits water into hydrogen and oxygen. The electricity can come from various sources, but ideally, renewable or clean energy sources such as wind, solar, hydroelectric, or nuclear power are used to ensure the process is environmentally friendly and produces green hydrogen. In summary, electrolysis uses electrical energy, preferably from renewable sources, to power the splitting of water molecules.