Although hydrogen is one of the most abundant elements on earth, in its pure form it is rare. Extracting hydrogen from its compounds requires a lot of energy. Although these energy sources can be diverse, the most popular hydrogen production method is carbon dioxide intensive. Most of the world’s hydrogen production consists of “grey hydrogen,” produced via steam methane reforming (SMR), which forms both hydrogen and carbon dioxide. In contrast, the term “blue hydrogen” is reserved for hydrogen production that involves carbon capture and usage or the storage of emitted carbon dioxide. Additionally, the electricity intensive electrolysis of water is yet another process for producing hydrogen and is the only carbon-neutral technique (provided that renewable energy sources can be used); this is known as “green hydrogen.”

There are generally two ways to use (green) hydrogen in steel production. First, it can be used as an alternative injection material to PCI, to improve the performance of conventional blast furnaces. Although the use of PCI is common, the first pilot plants using hydrogen injection have recently been set up to assess decarbonization potential. However, while the injection of (green) hydrogen into blast furnaces can reduce carbon emissions by up to 20 percent, this does not offer carbon-neutral steel production because regular coking coal is still a necessary reductant agent in the blast furnace.

Second, hydrogen can be used as an alternative reductant to produce DRI that can be further processed into steel using an EAF. This DRI/EAF route is a proven production process that is currently applied using natural gas as a reductant, with access to a cheap natural gas supply. However, the direct reduction process can also be performed with hydrogen. Based on the use of green hydrogen as well as renewable electricity from wind, solar, or water, a DRI/EAF setup enables nearly carbon-neutral steel production.

In more detail, a large-scale, green hydrogen-based DRI/EAF steel production process involves the following core process steps:

1. Green hydrogen production. Green hydrogen is produced by electrolyzing water in a process that requires significant amounts of electricity. Obtaining sufficient electricity from renewable energy sources will be the key challenge for green hydrogen production.

2. DRI production. In the DRI plant, iron ore in the form of DR pellets8 is reduced with hydrogen in order to form DRI.9 Using hydrogen as the reductant releases only water (i.e., it does not produce carbon emissions).

3. Raw steel production using an EAF. In the EAF, the DRI is heated and liquified together with steel scrap to produce raw steel. The use of electricity in this process (assuming it is from renewable sources) does not lead to any carbon emissions. 

The Green Hurdle
Managing the transition from fossil fuels to hydrogen without hurting the country’s economic momentum is a challenge in itself. Pricing will be key as capturing and transporting hydrogen is expensive.