Steel, Cement, a​n​d CO2

Steel, Cement, and CO2

In the drive to cut CO2 emissions, industrial emissions of CO2 represent a huge hurdle. 

Important industrial processes, such as the making of steel and cement, produce large quantities of CO2. The steel industry accounts for 7% of worldwide CO2 emissions, while producing cement accounts for 5%.

The German steel industry is being forced to address the issue because of Germany’s goal to cut CO2 emissions by 90%.

Salzgitter, a large German steel producer, is developing a “technically feasible but not economically viable” concept to replace fossil fuels, mostly coal used in blast furnaces, with hydrogen. And the hydrogen will be produced by wind farms using electrolysis.

But Salzgitter isn’t proceeding with the replacement of its blast furnaces because it can’t do so without government intervention.

It requires $1.5 billion in government subsidies just to begin making the required investment, and the steel that’s produced is far more expensive than steel made using coal.

In other words, Salzgitter must invest large sums in processes that are more expensive than existing processes which results in making steel that can’t be sold in a competitive market.

Salzgitter advertisement showing steel that is the same but different with 95% of the CO2 removed in 2050.

This proposal for converting steel production from fossil fuels to hydrogen is part of the hydrogen fantasy as described in the recent article, A Hydrogen Fantasy. (There won’t be enough wind and solar to support replacing fossil fuels for the generation of electricity, plus all the other needs, such as steel production.)

The next most important industrial contributor to C02 emissions is the making of cement.

In this case, much of the CO2 is from the material itself, while some of it comes from the fuel needed to create the heat that’s required to convert limestone to cement.

Quoting from an article on cement, “The primary component of cement is limestone. To produce cement, limestone and other clay-like materials are heated in a kiln at 1400°C and then ground to form a lumpy, solid substance called clinker; clinker is then combined with gypsum to form cement.”

Heating limestone releases CO2 directly, while the burning of fossil fuels to heat the kiln also results in CO2 emissions. 

Roughly 50% of the overall emissions of CO2 from the making of cement are from the limestone, and these emissions are nearly impossible to eliminate.


Steel and cement represent materials that are ubiquitous in modern society. Both are used for building highways and skyscrapers, while steel is found in the equipment used for their construction as well as in automobiles and appliances.

Once again we see the futility of trying to eliminate CO2 emissions.

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2 Replies to “Steel, Cement, a​n​d CO2”

  1. Reducing emission from making cement and steel is the most difficult part of reducing CO2 emissions to the atmosphere. I reviewed a great book on the engineering technology for new materials. Here’s the second edition,

    Portland cement is a mix of limestone (calcium) and sand (silicon) that, is sintered at very high temperatures, using heat sources such as natural gas. It’s mixed with sand, stones, and water to make concrete. As it cures it absorbs CO2 from the air over a few years, but not as much as generated from sintering. China makes and uses about 90% of world cement. Hopefully they are ending their building boom.

    Steel is reduced from iron ore by binding the oxygen from Fe oxides to carbon from coal. The furnaces may also be powered with coal, or natural gas. [Or charcoal, which introduced the Iron Age.] It’s possible to reduce iron ore with hydrogen, possibly from electrolysis using CO2-free electricity generation, if it’s cheap enough. [See]. Steel can also be refined from recycled scrap steel in electric furnaces.

    • Thanks for your comments.
      Recycled steel is melted using electric arc transformers that use large quantities of electricity.
      Other developing countries, such as India and Indonesia, and hopefully, all of subsaharan Africa, will use cement and replace China as a major producer of cement. That assumes the AGW climate change proponents don’t prevent these countries from developing and creating a better life for their people.
      No one knows how much CO2 is absorbed by concrete, but there is agreement that cement is a net contributor to atmospheric CO2.