Hydrogen itself is a colorless gas. However, there are around nine color codes used to identify hydrogen based on the source or process used to make it. These color codes are essentially nicknames used within the energy industry to differentiate between the types of hydrogen. Depending on the type of production used, different color names are assigned to the hydrogen. The most common colors of hydrogen are:

• Green hydrogen: This is produced through water electrolysis process by employing renewable electricity. The reason it is called green is that there is no CO2 emission during the production process.

• Blue hydrogen: This is produced from natural gas using steam methane reforming (SMR) or autothermal reforming (ATR) with carbon capture and storage (CCS) technology. The carbon dioxide produced during the process is captured and stored, making it a low-carbon option.

• Grey hydrogen: This is obtained by steam reforming fossil fuels such as natural gas or coal. In this process, the waste product CO2 is released directly into the atmosphere, making it not climate neutral.

• Turquoise hydrogen: This can be extracted by using the thermal splitting of methane via methane pyrolysis. The process removes the carbon in a solid form instead of CO2 gas.

• Purple hydrogen: This is made by using nuclear power and heat through combined chemo thermal electrolysis splitting of water.

• Pink hydrogen: This is generated through electrolysis of water by using electricity from a nuclear power plant.

• Red hydrogen: This is produced through the high-temperature catalytic splitting of water using nuclear power thermal as an energy source.

• Yellow hydrogen: This is made through electrolysis specifically using solar power, similar to the process used to create green hydrogen.

• White hydrogen: This is found naturally in underground deposits of geological hydrogen and is extracted through a process called gasification[[3]](https://www.acciona.com.au/updates/stories/what-are-the-colou...