{"id":1060,"date":"2021-10-15T07:34:56","date_gmt":"2021-10-15T07:34:56","guid":{"rendered":"http:\/\/nitk.acm.org\/blog\/?p=1060"},"modified":"2021-10-15T07:34:56","modified_gmt":"2021-10-15T07:34:56","slug":"fossil-free-steel","status":"publish","type":"post","link":"https:\/\/nitk.acm.org\/blog\/2021\/10\/15\/fossil-free-steel\/","title":{"rendered":"Fossil Free Steel"},"content":{"rendered":"\n

Steel is everywhere in our modern society, from the tools and machines we use in our homes to major infrastructure and construction work like hospitals, offices, and factories\u2014all of which we take for granted. Moreover, steel is also expected to play a crucial role in the renewable energy transition, with solar panels, wind turbines, hydroelectric dams, and electric vehicles all depending on it to one degree or another. So, it is ironic that the iron and steel sector ranks first when it comes to carbon dioxide emissions and second when it comes to energy consumption. According to the International Energy Agency, the sector directly accounts for over 2.8 billion tonnes of carbon dioxide emissions every year, corresponding to 7% of the global total, more than all road freight and transport emissions. <\/p>\n\n\n\n

This is mainly because the process of separating the iron ore to extract the molten iron metal requires a lot of energy and carbon that comes in the form of coke. This coke is produced by superheating coal in the absence of oxygen to get rid of the coal impurities and leaving behind a product with much higher carbon content. However, this coke production alone results in nearly 800 kilograms of carbon dioxide released for every tonne of coke. The coke produced is then added to iron ore and limestone, which is then transferred into a blast furnace where the air is blasted in at high temperatures. The oxygen in the air burns the coke at temperatures around 1600 \u25e6C, which reduces the iron ore to iron oxide and then to molten pig iron. The by-products of this process are carbon monoxide and yet more carbon dioxide. For every tonne of molten iron produced in a blast furnace, about 1.2 tonnes of CO2 is emitted. The resultant molten pig iron still has a carbon content of about 3.5 to 4%, which is too high for steel. This pig iron gets transferred to what is known as a basic oxygen furnace or LD converter, where a precise amount of air is injected at high pressures, which causes the oxygen to react with the unwanted carbon in the pig iron and brings the carbon content to less than 1%. At this point, we have essentially obtained steel, which can then be processed further as per the requirements. As we can see, this entire process releases an awful amount of CO2.<\/p>\n\n\n\n

In order to reach the goal of global temperature increases of a maximum of 2 \u25e6C as defined in the Paris Climate Accords in 2015, the emission from the steel industry should be decreased to a level of 400\u2013600 million tons per year in 2050 despite the forecasted production volumes showing an increase in demand.<\/p>\n\n\n\n

Unsurprisingly, the steel industry is under intense pressure to improve energy efficiency, recycle more, and switch to low carbon production processes. So far, however, the steel-making process has withstood engineers\u2019 best efforts to clean it up. Simply producing in greater efficiencies will not be enough, as there is a lack of low-cost replacements of critical inputs such as coal and coke. Manufacturers urgently need to find ways to completely re-imagine the process. Luckily, recent advances in renewable energy technology seem like they could lead us towards the previously unthinkable goal of virtually fossil-free steel. <\/p>\n\n\n\n

Growing access to low-cost renewable electricity in many countries worldwide is providing a competitive advantage to a technology called hydrogen-based direct reduced iron, or H-DR. The basic idea for this process is that water can be split into hydrogen and oxygen in a hydrogen electrolyser powered by renewables. The hydrogen produced replaces the coke that would typically be added to the iron oxide to reduce it. The hydrogen reacts with iron oxide at a relatively low temperature of about 800 \u25e6C to make what the industry calls sponge iron, which is currently produced by direct reduction using carbon monoxide. The by-product of hydrogen direct reduction is no longer carbon dioxide but simply water which can be recycled into the hydrogen electrolyser. The sponge iron produced does not need to go through a blast furnace and can be charged straight into an electric arc furnace with recycled scrap iron; sponge iron is also often used to substitute expensive scrap. However, there will still be some slag impurities to remove, so lime and a carbon source are added to the electric arc furnace. <\/p>\n\n\n\n

Simply because the iron ore reduction work is done by hydrogen instead of coke, researchers found that this method emits only 2.8% of the carbon dioxide currently emitted by existing coke and blast furnace systems. Researchers also calculated that H-DR uses 3.4 MWh of electricity for every ton of steel produced. As a result, this process would be cost-competitive against an existing integrated steel plant only if an internationally mandated carbon pricing of between \u20b93000 and \u20b96000 per tonne of CO2 emitted exists and assuming electricity costs only \u20b93.50 per kWh. These are, of course, big assumptions as there is no explicit carbon price in 86% of the world\u2019s countries, including India, and the current price of electricity in India is around \u20b96.09 per kWh. However, it is quite likely that every major carbon dioxide emitter on the planet will have to get used to the reality of carbon pricing in the near future.\u00a0<\/p>\n\n\n\n

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Comparison of blast furnace (left) and H-DR (right) consumption and emission figures<\/em><\/figcaption><\/figure><\/div>\n\n\n\n

As steel markets in the big consuming economies like China and India continue to mature, the availability of cheaper scrap material for recycling will increase, which is a good thing; nevertheless, the International Energy Agency estimates that H-DR will need to account for at least 15% of all primary steel production by 2050. This equates to one new plant every month for at least two decades, starting in 2030, which will, in turn, raise electricity demand by 720 TWh by the middle of this century, which is equivalent to 60% of the sector\u2019s total electricity consumption today. All of which will need to be supplied via fossil-free energy sources like renewables and perhaps even small nuclear reactors, which is another hurdle altogether.\u00a0<\/p>\n\n\n\n

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Global steel demand and required decrease of emissions by 2050<\/em><\/figcaption><\/figure><\/div>\n\n\n\n

Currently, this idea of entirely fossil-free steel sounds farfetched, and it is clear that a sustainable transition for the iron and steel sector will not happen on its own; governments and policymakers will have to play a central role. Heavy subsidies will most likely be needed to help pay for the capital expenditure needed to get these industrial-scale processes up and running, and a global carbon pricing structure will be essential. Although 2050 is often used as a target date, it is argued that governments and decision-makers should have 2030 firmly in mind as the critical window to facilitate the transition. It is safe to say that these issues will undoubtedly be topics of great discussion at the pivotal United Nations Climate Change Conference or COP26 climate conference to be held in Glasgow in November 2021, which is something we all can look forward to.<\/p>\n\n\n\n

– By Viswesh P, Third Year Department of Metallurgical and Materials Engineering<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

Steel is everywhere in our modern society, from the tools and machines we use in our homes to major infrastructure and construction work like hospitals, offices, and factories\u2014all of which we take for granted. Moreover, steel is also expected to play a crucial role in the renewable energy transition, with solar panels, wind turbines, hydroelectric…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[10,27],"tags":[363,364],"class_list":["post-1060","post","type-post","status-publish","format-standard","hentry","category-tech","category-yantrika","tag-fossil-free-steel","tag-renewable-energy"],"_links":{"self":[{"href":"https:\/\/nitk.acm.org\/blog\/wp-json\/wp\/v2\/posts\/1060","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nitk.acm.org\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nitk.acm.org\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nitk.acm.org\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/nitk.acm.org\/blog\/wp-json\/wp\/v2\/comments?post=1060"}],"version-history":[{"count":1,"href":"https:\/\/nitk.acm.org\/blog\/wp-json\/wp\/v2\/posts\/1060\/revisions"}],"predecessor-version":[{"id":1063,"href":"https:\/\/nitk.acm.org\/blog\/wp-json\/wp\/v2\/posts\/1060\/revisions\/1063"}],"wp:attachment":[{"href":"https:\/\/nitk.acm.org\/blog\/wp-json\/wp\/v2\/media?parent=1060"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nitk.acm.org\/blog\/wp-json\/wp\/v2\/categories?post=1060"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nitk.acm.org\/blog\/wp-json\/wp\/v2\/tags?post=1060"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}