Paths to green steel production: Part 2
Around a third of industrial CO₂ emissions worldwide come from metal production. How can CO₂ emissions in the production of crude steel be reduced as efficiently as possible? Technologies are already available that could significantly reduce CO₂ emissions from steel production through the use of renewable energies, in particular green hydrogen. But there are still some hurdles on the way to green steel.
Two types of steel production
There are basically two ways to produce steel.
- On the one hand by means of a blast furnace based on coke - or in future also hydrogen - as a reducing agent,
- on the other hand by means of an electric arc furnace (EAF), which melts the ore by means of heat radiation from electric arcs.
In Europe, EAFs currently account for 42% of crude steel production. At 0.7 tons per ton of steel, the carbon footprint of EAFs is significantly better than that of conventional blast furnaces, which is 2.3 tons per ton of steel. In addition, electric arc furnaces offer the possibility of using only electricity from renewable energy sources in the future.
"Due to the uncertain price development of green hydrogen and the rising CO₂ emission prices, the level of which cannot be precisely predicted, steel manufacturers should opt for fuel-flexible direct reduction technologies. The mix of natural gas and green hydrogen as a reducing agent gives them greater room for maneuver," says Ito.
Growing amount of research on the topic
A growing number of researchers are currently looking for ways to make the metal industry more sustainable.
Dierk Raabe and Martin Palm, two scientists at the Max Planck Institute for Iron Research in Düsseldorf, are working on making the production and processing of steel more sustainable. One potential option is to replace some of the coal with biogas, methane and, above all, hydrogen. "From a climate protection perspective, hydrogen would be the most favorable option if it is produced using electricity generated from renewable sources," says the Max Planck researchers.
Conversion to hydrogen
The German government's national hydrogen strategy includes the transformation of the steel industry as a central element. There have already been initial attempts by major manufacturers such as ThyssenKrupp and Salzgitter to replace coal with hydrogen in steel production, but experts say the transition will not be easy.
"Decarbonization with the help of hydrogen is a huge challenge, as the production technology has to be completely converted and an infrastructure has to be set up," says Hubertus Bardt, Managing Director and Head of Research at the Cologne Institute for Economic Research, in an interview with tagesschau.de.
"In order to produce steel with hydrogen on an industrial scale, Max Planck researchers are trying to accelerate the chemical reaction. They are also investigating the possibility of producing steel in a completely new process using hydrogen plasma.
Improved corrosion protection and a higher recycling rate could also reduce the CO₂ and energy footprint of metal products.
reduce. As iron aluminides are corrosion-resistant, lightweight and easy to recycle, they are a sustainable alternative to steels. By adding boron, Max Planck researchers have managed to optimize the alloy for use at high temperatures, for example in turbines.
turbines, for example," writes the Max Planck Institute.
Problems with electrification
"Electrification is certainly the main factor that will contribute to the decarbonization of industry," says Gerwin Drexler-Schmid, an expert on the decarbonization of industry at the Austrian Institute of Technology. As a result, the demand for electricity will rise sharply in the coming years. "The availability and transportation of electricity are certainly the crux of the matter."
However, electrification is still associated with major challenges, particularly in energy-intensive industries such as the steel and chemical industries. "Compared to a conversion from gas to hydrogen, the need for conversion from gas to electricity is enormous," says Tobias Fleiter, Business Unit Manager in the Energy Technologies division at the German Fraunhofer Institute.
According to Fleiter
- new connections to the power grid with high-voltage lines are required,
- to cope with the high quantities of electricity and the high voltage level.
- The high electricity prices make a complete switch to electricity hardly economical.
- The energy efficiency of electrification is often not that much better today compared to gas because the steel industry requires such high temperatures.
- Only when the electricity comes purely from renewable sources will the carbon footprint of electricity improve.
Enormous quantities of renewable energies required
One of the cruxes of the switch to renewable energies is the fact that these and the corresponding transportation and storage capacities must be available in sufficient quantities.
Here is an example: technicians have calculated that we would need 12 terawatt hours of energy if all cars registered in Austria were electric. In comparison, the two voestalpine AG steelworks in Leoben and Linz require 33 terawatt hours.
Sustainable steel production requires green hydrogen equivalent to half of Austria's total electricity requirements. It is not yet clear how this amount can be provided, according to the NZZ. "However, Europe will hardly ever be able to produce hydrogen entirely on its own," Franz Kainersdorfer, Head of Voestalpine's Metal Engineering Division, told NZZ.
The problem of scrap use
However, the high use of scrap, which is extremely important for climate-neutral steel production, could itself become a problem. If steel is mainly produced in EAFs because the blast furnace route is shut down due to high emissions, scrap is to be used predominantly as a raw material. To achieve this, the proportion of scrap in Austria would have to double to two million tons in the next five to seven years.
Voestalpine Green-Steeltec electric blast furnaces
13 million tons of CO₂ are emitted every year in Austria to produce eight million tons of steel - this corresponds to around 15 percent of the country's total CO₂ emissions. This makes the largest domestic steel producer, voestalpine AG, the industrial company with the highest greenhouse gas emissions in Austria.
It has already launched a pilot project for the production of green steel. Two new EAFs are to go into operation by 2027. The aim is to make steel production CO₂-neutral from 2050 through gradual modernization (primarily through the use of green hydrogen).
The first step in its phased plan is the construction of two EAFs in Linz and Donawitz. The integration of the two green electricity-powered EAFs into steel production will enable the company to electrify energy-intensive processes, thereby cuttingCO2 emissions by around 30% from 2027 and reducing Austria's attributable emissions by 5% at the same time.
