“The World’s Steel Comes at a Steep Climate Cost. A Swedish Company is Trying to Change That”, https://time.com/6171369/ssab-sweden-green-steel/ is an article recently published in an issue of Time. It describes the Swedish HYBRIT project of producing steel through hydrogen reduction. Is this method truly green, and are there ways to modify or improve it?

For any process to accurately claim to be green, its proponents must demonstrate that it does not emit greenhouse gases into the environment. Most steelmaking today is anything but green.

Iron ore (mostly iron oxide) is the majority of the material in every bit of steel most humans use. Unfortunately, steelmaking is one of the most carbon emission intensive processes in the world today, responsible for approximately 11% of global CO2 emissions and 7-9% of total greenhouse gas emissions per year.

Over 60% of global steel is produced using basic oxygen steelmaking. In this process, iron ore is first smelted in a coal-powered blast furnace to produce pig iron, i.e., iron with a carbon content of 3.8-4.7%. Oxygen is then added to remove some of this carbon, turning it into steel, but the removed carbon is in the form of carbon dioxide. When you factor in the coal burning as well, basic oxygen steelmaking is unfortunately a very carbon intensive process.

About 30% of steel is produced using an electric arc furnace, mostly to recycle steel. Scrap steel is smelted using electricity, and the resulting product adjusted with additives to get the desired type of steel. This is a highly energy-intensive process, and unless the electricity used is green, it too will be a carbon-intensive process.

Another method of making steel, and the one used in the Swedish project, uses hydrogen intensively. Hydrogen reduction steelmaking can use iron produced by direct reduction. Direct reduction involves heating the iron ore to a high temperature in the presence of a mixture of gases including hydrogen and carbon monoxide (specifically, hydrogen is heated to about 1,600°F with electricity, and then injected into a furnace containing iron ore pellets); this helps remove the oxygen from the iron oxide, and produces 97% pure iron. This iron can then be smelted in an electric arc furnace, where impurities can be removed and other elements such as carbon, chromium, etc. added to produce steel.

Hydrogen reduction steelmaking cannot be green unless the method used to produce the hydrogen, and the energy involved in heating the iron ore to the required temperatures, are green and carbon-neutral.

SSAB’s HYBRIT plant, which uses hydrogen reduction, produces the hydrogen they use via the electrolysis of water, which separates the hydrogen and oxygen with electricity. SSAB claims to generate this electricity using renewable energy.

The Swedish efforts in Lulea are highly laudable, but there is a
certain alternative method of producing hydrogen that can improve this process. First, let’s look at ways of producing hydrogen that aren’t green.

Consider these methods of producing hydrogen:

CH4 + H2O + heat → 3H2 + CO; here, methane and water produce hydrogen, but it also produces carbon monoxide.

CO + H2O → H2 + CO2; in this reaction, carbon monoxide plus water releases hydrogen, but it also produces carbon dioxide.

CH4 + 2H2O → 4H2 + CO2; methane and water can produce hydorgen, but again it’s at the cost of creating carbon dioxide.

So none of these popular methods are green – they all produce greenhouse gases.

Now consider this alternative reaction (Patent pending):

3CH4 + 4Al (scrap) → 6H2 + 0.99 Al4C3
In this reaction, methane and aluminum react to produce hydrogen and aluminum carbide.

This process is green, because even though methane is used, carbon gases are not emitted. It also has the advantage of producing aluminum carbide, a valuable compound used in industry that can sell for hundreds or even thousands of dollars per kilogram.

This process is of obvious benefit to any company interested in producing green steel, as it produces the hydrogen needed for reduction at a considerable profit. Even green electrolysis does not do that.

A possible challenge with this method is that worldwide aluminum supply is limited. However even scrap aluminum can be used in this process. Regardless, the advantages of producing green hydrogen at a profit should be obvious.