There are different types or colors of hydrogen based on process and sources of energy. Black, Gray, Blue and Green. Black hydrogen is produced through coal or lignite gasification (black or brown) and it tends to be mostly carbon intensive processes. Gray hydrogen is produced through a process called steam methane reformation (SMR) of natural gas or methane (grey) and it also tends to be mostly carbon intensive. Blue hydrogen is produced through natural gas or coal gasification combined with carbon capture storage (CCS) or carbon capture use (CCU) technologies to reduce carbon emissions processes but it tends to be less carbon intensive due to carbon capture technique. Green hydrogen is produced via electrolysis method, the splitting of water into hydrogen and oxygen with electricity generated from renewable energy sources such as solar or wind. This is the most environmentally sustainable way of producing hydrogen. The electrolyser technology is essential to the environmentally friendly hydrogen manufacturing process. There are two types of electrolysers: alkaline and polymer electrolyte membrane (PEM), today’s commercially accessible methods for producing eco-friendly hydrogen. Additionally, the commercialization of advanced electrolyser technologies such solid oxide and anion exchange membrane is almost complete.