The world is still hungry for steel. The US consumed just under 100 million t of the metal in 2021 alone. Used in industry and the transport sector such as in cars, trucks, aviation, rail and shipbuilding, steel is the most important construction and engineering material in modern societies.
Also used in electricity power line towers, natural gas pipelines, machine tools and military weapons, it is difficult to imagine our modern world without it.
However, the production of iron and steel also creates the single biggest industrial CO2 footprint, recorded at 2.6 Gt/yr in 2020, according to the International Energy Agency (IEA). This exceeds the total emissions of road freight worldwide and accounts for 7% of global CO2 emissions, stacked at approximately 37.12 billion Gt/yr. Emissions of this scale are largely due to the vast quantities of coking coal required for steel production, needed to transform iron ore to steel via a chemical reaction. Because of this, the sector obtains 75% of its energy from coal, the dirtiest fossil fuel. Demand for steel is only going up. Steel producers will need to halve their CO2 emissions from the steel-making process by 2030, rising to a 90% cut in emissions by 2040, in order to meet the obligations outlined in the Paris Agreement. The industry requires a more sustainable alternative, and green steel could pave the way towards decarbonising the sector.
What is green steel?
Green steel is steel that is manufactured without the use of fossil fuels. Whilst this may seem implausible at present, given the magnitude of emissions at stake coupled with steel’s centrality to modern life, innovative technologies are already being developed to help the industry on its way. Substituting coal with green hydrogen is a promising decarbonisation pathway. When water (H2O) is split via electrolysis, hydrogen and oxygen are produced as separate elements. If the electrolyser used is powered by electricity that is produced from renewable energy sources, such as solar or wind, the hydrogen produced can be labelled green hydrogen. This is the cleanest form of hydrogen available as its production uses renewable energy and therefore does not produce carbon emissions as a byproduct.
Rather than using coking coal as a heat source and catalyst to convert iron ore into steel, green hydrogen can be used to convert iron ore into sponge iron, which can then be processed to create green steel.
Massive undertaking means massive opportunity
Whilst the prospect of green steel is promising, the reality of implementing green hydrogen technologies on a sufficient scale is a daunting task. At current price levels, replacing coal with hydrogen would drive up the price of steel by about a third. This gap will likely narrow in the coming years, and could disappear completely by 2030, as carbon emission pricing is set to drive up the cost associated with the use of coal, causing the price of renewable electricity to decrease. In the longer term, large-scale production of hydrogen will also result in efficiency gains, and optimisation of hydrogen-based steel-making processes will drive down the costs of this alternative.
Written by Sundus Cordelia Ramli, Topsoe, Denmark.
Read the article online at: https://www.globalhydrogenreview.com/special-reports/31082023/pipe-dream/
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