INFOGRAPHIC AND EXPLAINER: What is green steel
Updated: Nov 20, 2022
What is green steel?
Green steel is becoming a buzzword on the continent as governments race to achieve net zero carbon emission targets.
African countries are expanding their infrastructure and growing their manufacturing industries, which is increasing their appetite for steel.
According to the World Steel Association, regular steel production accounts for between 7 and 9 per cent of global emissions because around three-quarters of global production happens in coal-fired plants.
Traditional steelmaking involves using a blast furnace, burning coal and emitting a lot of carbon dioxide.
And this is puzzling governments as countries begin to switch to e-mobility, and the construction sector, including heavy use in roads and bridges, looks to alternative solutions that promise lower zero carbon emissions.
Green steel - manufacturing steel without resorting to fossil fuels - significantly reduces industry's carbon footprint. It swaps the use of coal with clean electricity and green hydrogen, to eliminate the "dirtiest" (carbon dioxide emitting) part of processing.
Some African countries, mostly in North Africa, have already adopted cleaner technologies like direct reduced iron-electric arc furnaces (DRI-EAF).
In traditional steel making, raw iron (Fe) is mined from rock that is rich in iron and then pelletised using a furnace (which does not melt the iron). The iron pellets would then traditionally be refined into steel by applying heat to melt the iron, in a furnace.
However, a more recent process for turning iron into steel has been developed, known as reduction, to create direct reduced iron (the DRI in the DRI-EAF above). This usually uses a mixture of carbon monoxide and hydrogen derived from natural gas, electricity or gasified coal plants, which is blown into the heated iron, prior to the iron being refined into steel.
According to the Institute for Energy Economics and Financial Analysis, this process emits less carbon than the basic oxygen furnace (BF-BOF) process, used in 71% of global crude steel production in 2021.
In addition, hydrogen - and even, green hydrogen - can completely replace the carbon dioxide used in the DRI process.
Green hydrogen is a crucial component of the green steel production process. When renewable energy is used to create hydrogen from water, via electrolysis, it is completely free of carbon dioxide emissions and is known as green hydrogen. When hydrogen is burned (oxidised) to create energy, it emits only water.
When the furnaces used in the making of iron pellets as well as for refining steel are completely powered by renewable energy and the reduction method is employed, the result is green steel.
Infographic by Hope Mukami, bird story agency
Explainer by Conrad Onyango, bird story agency