…Making Climate Friendly Steel…
Producing steel and cement result in large CO2 emissions. The steel industry accounts for 7% of worldwide CO2 emissions, while producing cement accounts for 5%.
Can steel be climate friendly?
Currently, there are two predominant methods for producing steel.
- The first uses a basic oxygen furnace (BOF) where pig iron from a blast furnace is converted to molten steel by removing carbon with oxygen. Approximately 80% of the CO2 emissions are from the blast furnaces, 20% from coking ovens, and a small amount from the BOF.
- The second method uses an electric arc furnace (EAF), where scrap steel is melted using an arc created using an electric arc furnace transformer. This process is nearly free of CO2 emissions.
Approximately 75% of the world’s steel is made using blast furnaces and the BOF process, while 25% is made using EAFs. A small amount of steel has been made using the direct reduction of iron (DRI) process with natural gas. A tiny amount has been made by replacing coking-coal with charcoal.
The steel industry is pursuing two approaches for eliminating these CO2 emissions.
- The first relies on carbon capture and sequestration (CCS), while continuing to use blast furnaces and BOFs.
- The second uses the Direct Reduction of Iron (DRI-H) process with hydrogen, rather than natural gas, as the reducing agent.
Steel using CCS
There are several proposals for reducing the amount of CO2 produced during the steel making process, and then capturing the remaining CO2 and sequestering it underground.
This list may not be all-inclusive, but is probably representative. A description of each process is in the report, Decarbonization options for the Dutch steel industry, which is available from the Internet. Essentially, they all try to use as much of the emitted CO2 as possible during the steel making process, and then use carbon capture and sequestration (CCS) to dispose of whatever CO2 remains.
- Top gas recycling blast furnace (TGR-BF)
- ULCOWIN and ULCOLYSID
Sequestering CO2 underground in huge quantities, annually, without leakage for centuries, is problematic. Liquifying and transporting liquid CO2 under high pressure to where it can be pumped underground results in large additional costs.
Crude steel is produced in forty countries, so the CCS option depends on whether it’s possible to locate places around the world where CO2 can be securely sequestered.
DRI – Hydrogen
The best way to introduce this subject is to quote a report from Sweden’s, SSAB, LKAB and Vattenfall corporations on their joint venture to produce steel using hydrogen with their Hybrit process for fossil-free steel.
“The HYBRIT system uses hydrogen – produced using fossil-free electricity instead of fossil coal – and releases water instead of carbon dioxide. If realized on an industrial scale, the technology could make Sweden the world’s first country to produce fossil-free ore-based steel.”
Two supporting comments from the report, related to the accompanying diagram, help explain the process:
- The existing direct reduction method needs to be adapted to reduction with hydrogen to eliminate carbon dioxide emissions. The off-gas of the reduction process would be water, according to the simplified reaction: iron ore
+ hydrogen => iron + water. The result is a solid porous sponge iron, suitable for steelmaking.
- The Electric Arc Furnace (EAF) is used for heating and melting charged materials by means of electric current. The use of EAFs allows steel to be made from up to 100% scrap metal, or as in the HYBRIT concept, from a mix of direct reduced iron and scrap. Similar to the reference process, the liquid steel is tapped into a ladle where the final chemical composition and the temperature of the steel is adjusted, before it is cast into crude steel slabs in the continuous caster.
Bottom line, the DRI-Hydrogen (DRI-H) process eliminates blast furnaces and coking coal.
Converting a traditional steel mill to DRI-H requires a huge investment, possibly billions of dollars. The precise amount is not known as only experimental work on DRI-H has been done thus far.
Referring to a process similar to HYBRIT’s, the CEO of Salzgitter steelworks in Germany said it has developed a “technically feasible but not economically viable concept to replace fossil fuels.” ThyssenKrupp, also in Germany, has announced it will invest $10 billion in converting its steel-making process over the next decade.
At this time, it appears as though DRI-H investment is around 30% higher than for a greenfield traditional steel-making plant.
The cost of producing steel from the DRI-Hydrogen process is highly dependent on the cost of green hydrogen, while the cost of green hydrogen is dependent on the cost of electroayzers and the cost and availability of green electricity.
Ramifications of DRI-H
As the CEO of Salzgitter indicated, DRI-H steel will be uncompetitive with traditionally produced steel. The ramifications of this fact are important.
- It could lead to CO2 border taxes, disrupting trade around the world.
- It could evolve into establishing a bifurcated steel industry where some countries use DRI-H, while others retain traditional steel-making processes.
The only solution to these two outcomes is for governments to intervene and force all countries to adopt DRI-H which would lead to higher costs for steel everywhere.
Products made from DRI-H steel will cost more than products made from steel produced the traditional way. These products include:
- Automobiles, trucks, kitchen appliances, home heating and air-conditioning systems, wind turbines, ships, transformers, water pumps, electric motors, locomotives, tools of virtually every description, elevators, cables, pipes, buildings, and many more.
Higher costs hurt the poor and middle class, but developing countries in Africa, South America, Asia and islands around the world, will be especially hard hit and find it even harder to improve the living conditions of their citizens.
Producing steel and cement results in CO2 emissions. The steel industry accounts for 7% of worldwide CO2 emissions, while producing cement accounts for 5%.
It will be impossible to achieve a zero carbon society by 2050 without eliminating CO2 emissions from the production of steel and cement. Green hydrogen is the crucial component of any strategy to eliminate CO2 emissions from these products, yet producing the required quantities of green hydrogen is, by itself, problematic … and expensive.
In any event, the cost of steel made from the DRI-H process will be greater than the cost of steel made the traditional way, and the ramifications of high-cost steel are unavoidable.
The difficulties surrounding the elimination of CO2 emissions from the production of cement are even more daunting.
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Related Article: Steel, Cement and CO2