By now, you’ve surely heard that hydrogen as a fuel source is taking off. From a record setting test flight of a hydrogen-powered plane to government funding of hydrogen technologies to new studies that are looking to split water to make green hydrogen, hydrogen has taken over the clean energy reporting space.
But with this new type of energy comes a whole glossary of terms––in this case, colors! Let’s take a look at the rainbow of hydrogen.
Green Hydrogen: is a type of hydrogen gas produced through a process called electrolysis, where an electric current is passed through water to separate the hydrogen and oxygen atoms. The electricity used in this process is generated from renewable sources such as solar, wind, or hydroelectric power, making the hydrogen produced entirely emission-free. Green hydrogen “is so expensive that it is largely commercially unviable and accounts for just 1% of total hydrogen production globally.”
Blue Hydrogen: is produced from natural gas, but with carbon capture and storage (CCS) technology to reduce the carbon emissions associated with the process. The natural gas is first converted into hydrogen gas through steam methane reforming (SMR) or partial oxidation, and then the resulting carbon dioxide is captured and stored in underground geologic formations. While blue hydrogen is not entirely emissions-free like green hydrogen, it is still considered a cleaner alternative to other colors of hydrogen.
Gray Hydrogen: is produced from fossil fuels like natural gas and is the most common type of hydrogen and is also produced through steam methane reforming (SMR) or other processes that use fossil fuels like natural gas, coal, or oil as the feedstock. Unlike blue hydrogen, this process releases carbon dioxide into the atmosphere as it is not captured.
Brown hydrogen: is a term used to describe hydrogen produced from coal gasification, which is similar to SMR but with coal instead of natural gas as the feedstock. Brown hydrogen is also a significant contributor to greenhouse gas emissions and is generally not considered a sustainable or clean energy source.
Turquoise hydrogen: is a new term used to describe hydrogen produced from natural gas using a process called pyrolysis, which involves heating the gas to high temperatures in the absence of oxygen. This process generates hydrogen and solid carbon as byproducts, which can be used in various applications. The carbon byproduct can potentially be used in products such as building materials, making it a potentially valuable approach to reducing carbon emissions. However, turquoise hydrogen is not yet widely produced or used in commercial applications.
While this is a pretty good overview, this is not an exhaustive list. Here are even more colors, if you’d like to fill in your full rainbow.
