It replaces the massive amounts of coal that is used. It changes from (simplifying)
2 Fe2O3 + 3 C → 4 Fe + 3 CO2
to
Fe2O3 + 6 H2 → 2 Fe + 3 H2O
At the moment emissions are: 1.4 kg CO2 per kg of steel produced. And westernized countries will use 321 kg of steel per capita per year.
So switching to hydrogen could save about 500kg of CO2 per capita. Carbon capture of the fumes could help alleviate some 30% of that. Direct air capture is just not feasible, or wayy to expensive compared to just using H2.
In any case, even with H2; 321 kg of steel per capita will have to be reduced (main uses: construction, transport, industry, pipes, machines, weapons)
So switching to hydrogen could save about 500kg of CO2 per capita. Carbon capture of the fumes could help alleviate some 30% of that. Direct air capture is just not feasible, or wayy to expensive compared to just using H2.
In any case, even with H2; 321 kg of steel per capita will have to be reduced (main uses: construction, transport, industry, pipes, machines, weapons)