3 Main Types of Hydrogen

The debate around hydrogen energy is getting more and more attention. Something which was a niche feedstock product serving heavy industry is now very much at the forefront of decarbonising the transportation and shipping world. Hundreds of billions of dollars are being invested into projects aimed at helping achieve net-zero targets and creating zero-emission fuel. Against that backdrop, let's take a closer look at the different options available.

The most common form of hydrogen, it's created from fossil fuels and the process releases carbon dioxide which is not captured.

The process used to create hydrogen from natural gas is called steam methane reforming (SMR), where high-temperature steam (700°C–1,000°C) is used to produce hydrogen from a methane source, such as natural gas. In steam methane reforming, methane reacts with steam under 3–25 bar pressure (1 bar = 14.5 pounds per square inch) in the presence of a catalyst to produce hydrogen, carbon monoxide, and a relatively small amount of carbon dioxide. Steam reforming is endothermic — that is, heat must be supplied to the process for the reaction to proceed.

There is also a gasification process which uses coal as a feedstock, creating brown hydrogen, which also releases carbon dioxide and can be put in the same category as grey.

The head of business development at the renewable energy giant Enel has described hydrogen as a "climate killer" as it stands right now due to almost all of it being grey: “98% of it is produced from steam reforming and gasification, which equates to yearly carbon emissions comparable to that of Indonesia and the UK combined," he said. "Just 2% is produced from electrolysis.”

Clearly then, grey hydrogen is not a long-term solution.