Deep Decarbonization of Hard-to-abate Iron & Steel Sector - Challenges and Opportunities

ISfIM organized a distinguished lecture on Deep Decarbonization of Hard-to-abate Iron & Steel Sector - Challenges and Opportunities on 16 August 2023 at School of Mechanical Engineering, Nanyang Technological University, Singapore. The lecture was given by Dr Debashish Bhattacharjee, Vice President, Technology and R&D, Tata Steel, India.

Lecture Abstract:

The earth has seen at least 5 mass extinctions in the last 500 million years the last of which was some 66 million years ago. After each mass extinction, 75% to 90% of all existing animal and plant species vanished and new species came up to proliferate earth. The reasons for mass extinctions, although open to scientific debate, were climate change caused sometimes by extreme volcanic activity and sometimes by impact of external objects such as large asteroids. Currently, by many indications, the earth is facing another mass extinction. This time the cause is man-made. Emission of gases such as CO2 from industrial activity and transportation, result in heating up of the earth’s atmosphere. This gradually raises temperature of the earth resulting in melting of glaciers and polar ice-caps, raising sea levels, change in weather patterns, making cyclones, floods, heat waves, cold storms more severe. Although man-made CO2 constitutes only about 4% of the total CO2 in the atmosphere, human contribution has increased CO2 from around 2.5 GT (Giga Tonnes) in 1900 to 36.4 GT in 2022. Average temperature of the earth has indisputably gone up by 1 °C in the same period. Out of this increase, rise by 0.5 °C has happened after 1970s. If it goes up by another 2 °C, the changes in climate will be irretrievable and the effect on human civilization, devastating. In order to restrict rise in temperature, CO2 emission needs to be curtailed.

In 2022, total man-made CO2 emitted to the atmosphere was around 36.4 GT. Out this, roughly 7% to 8% was from the global iron and steel industry, 40% from power sector, 25% from transportation. The power sector has scalable green technologies enough in reach to have reliable roadmap for decarbonization. Transportation has a clear commercial roadmap to becoming green through electric vehicles and hydrogen as fuel. A few sectors, such as iron and steel, cement and aviation, have problem of large scale, difficulty of reach, and unavailability of scalable, cost-effective technologies. Global man-made CO2 emission is likely to significantly reduce from current levels because of “greenification” of power and transportation sectors. In the absence of CO2 abatement technologies at scale and at appropriate price, if business as usual continues, the contribution of iron and steel industry to global man-made CO2 will be 33% by 2050. This will be unacceptable. Societal pressure will threaten extinction of iron and steel industry in the manner we know it today. Solving the CO2 problem is an existential issue for the iron and steel industry. Actions must start now.

CO2, in the iron and steel industry, mainly comes from the removal of oxygen from iron oxide that constitutes the natural raw material. This process of removal of oxygen, called reduction, can be carried out by carbon, hydrogen or any other substance that has a strong affinity for oxygen. Carbon, traditionally, has been commonly the most available reducing substance.

The world produces about 1.8 billion Tonnes (T) of steel. The average CO2 emission is around 2.5 T of CO2 per T of steel. One of the most common technologies for production iron uses the blast furnace. A blast furnace is a vertical shaft in which iron ore, coke (a form of solid carbon produced by heating coal in absence of air) and some fluxes (substances such as calcium oxide, that help in removing impurities from liquid iron). From the bottom of the furnace, hot air (the blast) and some fine coal particles are injected. The oxygen in the blast reacts with carbon in coke and in the coal particles to produce carbon monoxide. This carbon monoxide and some of the carbon from coke react with the iron oxide to remove oxygen and form carbon dioxide. Nearly 85% of the CO2 produced in the iron and steelmaking comes from the blast furnace. The blast furnace route produces, on the average, 2.3 Tonnes of CO2 per Tonne of steel. Solving the CO2 problem associated with the blast furnace will resolve decarbonisation problem of iron and steel sector to a large extent.

Most of the world’s 1.8 billion Tonnes of steel are produced through the blast furnace route. This technology has evolved and has been perfected across the globe over 300 years. The blast furnace is flexible in accepting a wide range of raw materials quality and produces the cheapest liquid iron that subsequently goes for making steel. Installation of blast furnaces is capital-intensive and these furnaces can last 12 to 15 years with normal maintenance and even beyond 30 years with one relining of internal refractory bricks. Suddenly stopping these furnaces, short of their full life is economically imprudent. Therefore, blast furnaces cannot be simply wished away. In order to deep-decarbonise, the iron and steel sector must find a solution for the CO2 from the blast furnace while also looking for alternate technologies.

There are three ways of decarbonising - Carbon Direct Avoidance (CDA) in the blast furnace, Carbon Capture Utilisation and Sequestration (CCUS) outside the blast furnace, and alternate ironmaking technologies. In CDA approach, carbon can be replaced by other reducing agents such as hydrogen. This would need production, storage and transportation of hydrogen in extremely large quantities. CCUS technologies are in three parts - carbon capture, utilisation, and sequestration. New technologies include hydrogen-based direct reduction, or technologies such as HISARNA, or even use of reducing agents that are neither carbon nor hydrogen. The talk will highlight work being done across the world to accelerate technology development for decarbonization of a difficult to abate sector such as iron and steel production.

Speaker Biography:

Dr Debashish Bhattacharjee completed BE in Metallurgical Engineering from Jadavpur University, MTech from IIT Kanpur and PhD in 1993 from University of Cambridge, UK, with Nehru-Cambridge Scholarship. He carried out two post-doctoral research assignments, one at Rolls Royce Technology Centre, Cambridge, and the other at University of Birmingham, UK. He joined Tata Steel in the R&D function in 1996 and headed the function as Chief Research & Development and Scientific Services between 2002 and 2009. In 2009, he was seconded to Tata Steel Europe as Group Director Research, Development & Technology for Tata Steel Group, based at Netherlands. In 2017, he returned to India to set up business in materials beyond steel. Dr Bhattacharjee is an expert in development of materials and decarbonisation technologies. He has more than 60 international peer reviewed journal publications, 7 edited books and 40 patents.

Dr Bhattacharjee is a Fellow of the Indian National Academy of Engineering and of the Indian Institute of Metals. He is Visiting Professor at the Imperial College London, at the University of Warwick, UK, and at the University of Science and Technology, Beijing, China. Currently he is Vice President, Technology and R&D, Tata Steel and is based in Kolkata. Dr Bhattacharjee’s hobbies include playing cricket and acting in plays.