Steel-making is a climate catastrophe in itself: in the process, hard coal is burned and CO2 emitted. In fact, it is one of the most carbon-intensive industries in the world. In addition, most steel is produced for emission-heavy products like cars or the Nord Stream 2 pipeline connecting Russian gas terminals with the German coast. Several steel-making companies in Austria and Germany are now trying something very new: using hydrogen in steel-making. On the surface, this comes as a huge improvement. To understand why this is a prime example of a false solution, a deeper look at these technologies is needed. But first, let’s dive into the details of both traditional and future steel-making.
Coking coal: a blast from the past
For centuries, steel-making was based on the same process. Steel is made of iron, but the material found in the earth is iron ore (mainly Fe2O3; Fe is iron and O is oxygen): the iron is bound with lots of oxygen. To get rid of it, steel makers use a type of hard coal called coking coal (see chapter two). The coal is baked in a coking plant and transformed into a solid, porous carbon fuel: coke. The coke is then thrown into the central aggregate of the steel plant: the blast furnace. Here, the carbon gets into contact with the iron ore, gradually robbing it of its oxygen until the residue is pig iron (iron with four percent carbon to lower the melting point by roughly 400°C). This robbing of oxygen atoms is also called reduction. The oxygen is emitted from the blast furnace as part of CO2, having reacted chemically with the majority of the coke. For the sake of completeness: the pig iron can then be alloyed at will with other metals in the converter. The result is steel.
Hydrogen: down with emissions
The only alternative that is considered feasible on an industrial scale is direct reduction. This name was assigned to this process because there is no liquid phase – solid iron ore is transformed directly to solid iron. Here, no coke is used and – in theory – no CO2 is emitted. Instead, hydrogen atoms reduce the iron atoms, and water molecules are emitted. The key stage in this process is called direct reduction of iron and the result is, once again, pig iron.
This would lower emissions substantially. For example, the second largest German steel producer, Salzgitter AG, calculates that if all blast furnaces were replaced, emissions (per tonne of steel) would decrease by between 82 and 95 percent. The 95 percent scenario would occur if only hydrogen was used for reduction, the 82 percent involves some methane in the process and would be the energetical optimum for the whole plant. However, if methane is used, some amount of CO2 is introduced into the blast furnace gas. If this process could be built and run on an industrial scale, the steel industry’s CO2 problem would be solved – or so it seems. Instead, there is a new problem: how to come by sufficient amounts of hydrogen to run a steel plant?
Hydrogen does not just ‘float around’ in the atmosphere. Most of it is bound in gasoline and liquid molecules, the most relevant being methane (CH4) and water (H2O). To obtain pure hydrogen either molecule has to be split up. In the case of methane this would cause additional CO2 emissions, and little would be won. In the case of water, this could be done through a process called electrolysis that does not produce any CO2. Electrolysis is the separation of hydrogen and oxygen by means of electricity. If – and only if – the electricity was generated without fossil fuels involved, it might be possible to make pig iron with very low CO2 emissions.
The problem is the amount of energy needed. To switch a steel plant from coke to hydrogen means to get rid of one energy source (fossil coal) and use another (wind or solar energy). Sadly, it is very hard to substitute a fossil fuel-based process with an electricity-based process. The Austrian steelmaker Voestalpine, for instance, has calculated that to switch their big steel plant in Linz to hydrogen through electrolysis would require 33 TWh of electricity per year. This is the equivalent of half of the annual Austrian electricity consumption, which amounted to 74 TWh in 2018!
It doesn’t stop there
Steel is not the only industry interested in hydrogen. The hydrogen fuel cell is one of two ways of powering electro-mobility. To reduce the emissions of individual mobility to near zero would require that all the energy currently produced from fossil fuels for transport to be generated from hydrogen instead.
The blast furnace and the electric car are just two examples for of a general trend – as fossil fuels are becoming less and less socially acceptable, alternative fuels like hydrogen gain importance. And this means that more and more electricity from non-fossil sources has to be generated. Model calculations for Germany show some of the implications: in 2018, German energy consumption was around 600 TWh including 46 percent from renewable sources. This includes not only energy taking the form of electricity but also gas, coal, and oil. Studies show that to reduce CO2 emissions in Germany to zero, renewable electricity production would have to go up to around 2,000 TWh by 2050, unless drastic reductions in energy usage and changes in transport patterns were achieved. The current planning of the Federal Government reflects these numbers.
Not only would this be much too late, but the amount of electricity from renewable sources would have to be multiplied by a factor of seven, requiring huge amounts of resources and mining (as explored in chapter 9.5), at enormous ecological and social costs.
Of course, these figures have to be taken with a pinch of salt. There are a lot of predictions involved, and political frameworks might change. But the figures broadly indicate the scenario we face.
Therefore, it’s becoming clear that a mere change in energy source will not solve the problem. Hydrogen is not the alternative. There is only one true alternative: bring down energy consumption. Drastically. Unconditionally. Fast.