In line with the current discussion about Germany as a steel production location, the German Aerospace Center (DLR) has now presented a study examining how the global steel industry can significantly reduce its CO2 emissions. Such a reduction is a recognized important starting point in the fight against global warming, as the production of iron and steel accounts for around nine percent of global greenhouse gas emissions. In their study, researchers at the DLR Institute of Networked Energy Systems analyzed several scenarios to determine how the introduction of new technologies could affect greenhouse gas emissions from global iron and steel production. The focus is on three technologies: carbon capture and storage (CCS), the use of hydrogen, and electricity-based iron production.

Far-reaching measures urgently needed

"The study shows that comprehensive and far-reaching measures are needed in the near future, accompanied by political framework conditions at the international level. This is the only way to sufficiently advance the defossilization of the steel industry while at the same time taking into account competitiveness in Germany and Europe. Another fundamental prerequisite is the rapid and massive expansion of electricity generation from renewable sources," summarizes Prof. Meike Jipp, DLR Executive Board Member for Energy and Transport. “This is also against the backdrop that, due to EU emissions trading, the costs of CO2 emissions will gradually rise in the future, making existing manufacturing processes more expensive. It is therefore important to create incentives for new technologies now and to implement them.”

Capturing and storing CO2 is not enough

Steel is produced in blast furnaces. Coke, a special type of coal, is the primary energy source used. CO2 emissions from steel production are correspondingly high: between 1.6 and 2.2 tons of CO2 are produced per ton of steel. Retrofitting existing blast furnaces with technologies that capture and store CO2 can significantly reduce CO2 emissions. "Our analysis shows that these technologies can reduce emissions in the short term because CCS enables the retrofitting of modern existing plants. In the long term, however, the emission reduction potential of CCS is insufficient,“ concludes DLR researcher Carina Harpprecht. She conducted the DLR study together with colleagues from the Energy Systems Analysis department. ”Electrification of the production process is the key strategy for achieving far-reaching reductions in emissions," Harpprecht continues.

Hydrogen replaces carbon-containing coke

The production of iron using sustainably generated “green” hydrogen is considered technologically promising. The hydrogen replaces the carbon-containing coke. As a result, almost no CO2 emissions are produced during iron production. Another alternative is still in its infancy: the electrolysis of iron ore directly with electricity, also known as “electrowinning.” It has the advantage that the electricity is used directly. If electricity is used to first produce hydrogen by means of water electrolysis, energy efficiency is lower and thus the CO2 footprint of iron and steel production is potentially higher.

Scenarios show: Climate targets pose major challenges for the steel industry

In 2020, the global steel industry already produced around 1,600 million tons of crude steel annually. By 2060, global steel production could grow to more than 2,600 million tons per year. In view of this development, global annual greenhouse gas emissions can only be reduced by up to 67 percent by 2060 in the best-case scenario (from 3.4 gigatons of CO2 equivalents per year in 2020 to 1.2 gigatons in 2060). Residual emissions come primarily from CCS technologies, which prevail in the cost-optimization scenario but whose long-term emission reduction potential is insufficient.

There is little time left

“This means that no scenario will achieve the goal of staying below the CO2 emissions budget set in this study for the global steel industry in order to limit the temperature increase to 1.5 degrees Celsius,” explains DLR expert Carina Harpprecht. “The steel industry also shows how important the next ten years will be for climate protection – and how little time remains to further develop and implement new technologies. The high investment costs in the steel industry and the long service life of existing blast furnaces, potentially combined with CCS, pose major challenges.”

Focus more on recycling

If primary steel production were to switch to sustainably produced hydrogen, the cumulative greenhouse gas emissions of the steel industry could be reduced by an estimated further 15 percent by 2060. However, this would still not be sufficient to meet the CO2 budget for the 1.5-degree target in this scenario framework. The sector must therefore achieve faster and more drastic defossilization and emission reductions that go beyond the values projected in the global scenarios considered. An efficient lever for this would be to reduce primary steel production while placing greater emphasis on steel recycling.

Low-carbon steel industry requires large amounts of renewable electricity

Whether hydrogen or electrowinning – the technological alternatives for reducing emissions in steel production massively increase the demand for electricity from renewable sources: According to a DLR study on the German steel industry, the electricity demand of the German steel industry in 2050 could be up to fifteen times higher than today.

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