Hydrogen - colorless, but colorful.

Gray, blue or green hydrogen? One thing is certain: Hydrogen is actually a colorless gas, yet there are many colorful names for the energy carrier. Behind them is a reference to the production method and the energy used in the process that makes the coveted H2 molecule sustainable.

The energy carrier of tomorrow

In the current discussion, hydrogen is considered the energy carrier of the future. This is primarily due to its diverse potential applications: from mobility to heat supply to conventional industry, hydrogen can serve as an efficient alternative to fossil resources. It can heat furnaces in the cement and steel industry, synthesize industrial waste gases into feedstocks for fertilizers, plastics and fuels, and serves as a basis for other important raw materials in the chemical industry.

Particularly in the steel industry - one of the most CO₂-intensive sectors - hydrogen can make a big difference, as carbon is traditionally used in the blast furnaces to produce pig iron. On the one hand, this provides the energy needed to melt the iron ores, and on the other hand it serves as a reducing agent, i.e. it binds the oxygen in the iron ores, producing pure iron. In this way, the blast furnace process currently generates 85% of the CO₂ emissions of the entire steelmaking process. Decarbonizing the steel industry with the help of hydrogen is therefore a huge opportunity for a more climate-friendly future.

However, the extent of this leverage and the potential for CO2 savings in industrial applications depends to a large extent on the production method of the hydrogen used.

From gray to green: it all depends on how it's made.

Gray hydrogen: Currently, hydrogen is mainly produced from fossil fuels - more precisely: from natural gas. In practice, this means that hydrogen and carbon dioxide are split under heat. After this process, the carbon dioxide (CO₂) is released unused into the atmosphere. This hydrogen is called gray hydrogen. The production of one ton of gray hydrogen produces around ten tons of CO₂. By way of comparison, this is about as much CO₂ as a person living in Germany produces on average per year, or a commuter with a 40km commute and a medium-sized gasoline-powered car over a period of six years.

The potential of blue hydrogen

The switch to green hydrogen in steel production is essential in the long term for achieving the UN climate targets. Plants running entirely on green hydrogen can save several million tons of CO2 in the steel industry alone. But at present the quantities of renewable energy available are not yet sufficient to meet the constantly rising hydrogen requirements of all industries. The thyssenkrupp Steel steel mill in Duisburg alone will need around 720,000 tons of hydrogen per year in the long term. That's a whole 247 million hydrogen-filled trucks a year! Therefore, an important form of transport for hydrogen is ammonia. This can be transported inexpensively in tankers. The ammonia is then split into hydrogen and nitrogen on site. With the help of ammonia, a worldwide market for low-carbon hydrogen will be established.

Before the energy transition is complete and sufficient electricity from renewable sources is available, the use of blue hydrogen will be necessary in the medium term to avoid CO₂ emissions. Because blue hydrogen also has a lot of potential. By using blue hydrogen, thyssenkrupp Steel in Duisburg can already save 20 million tons of CO₂ emissions a year.