5th April 2024
Green Steel
Steel manufacturing produces more CO2 than any other heavy industry, comprising around 8% of total global emissions.
Traditionally steel is made in a blast furnace where the iron ore is he@ted at high temperatures together with coal. As the coal burns it produces carbon monoxide which bonds with and removes oxygen in the iron ore so purifying it to produce metallic iron. The carbon monoxide binding with oxygen becomes carbon dioxide and is one of the main sources of carbon emissions. Other sources of emissions will vary depending how the furnace is heated etc.
The industry is developing various ways of producing steel without – or with reduced – carbon dioxide emissions – known as green steel.
Replacing coal with hydrogen: Green steel can be produced by using hydrogen to remove the oxygen from the the ore – producing water (H2O). Ideally this would be green hydrogen – ie hydrogen produced using renewable energy. This method of producing steel requires heating the furnace to a higher temperature.
Reusing existing steel: steel can easily be recycled in arc furnaces powered by electricity – which ideally would be electricity from renewable energy sources with no carbon dioxide emissions.
Around 30% of the world’s steel is made from recycled steel. However steel cannot be recycled endlessly without loss of quality. Each time it is recycled the proportion of unwanted elements such as copper, nickel and tin increases. On the other hand steel has long in-use life which means that the amount of steel made available for recycling does not at present keep up with the growing demand for more steel. Our modern economies are big users of steel!
(For more detail see https://theconversation.com/green-steel-is-hailed-as-the-next-big-thing-in-australian-industry-heres-what-the-hype-is-all-about-160282)
Which ever form of green steel is produced, the availability of large amounts of renewable energy is going to be critical.
As important will be the way the transition is managed as furnaces are large and highly expensive pieces of kit – ie needing substantial investment – and can take years to install which in some instances has led to workers being laid off – as is proposed at the Tata steel works in Port Talbot. (https://www.theguardian.com/uk-news/2024/mar/25/tata-port-talbot-job-losses-labour-subsidy?CMP=Share_iOSApp_Other).
Other important issues to address are how steel is used – with product design ensuring a long life, whether other materials could be used – timber for example in building construction, and how effectively scrap steel is collected and recycled.
Further reading – https://www.bbc.co.uk/news/business-64538296
The Green Tau 