The message to green hydrogen producers in India who might be thinking of the steel industry as a market is: perish the thought. Green steel production in India is unlikely to happen anytime soon, perhaps never.
‘Green steel’, or the steel produced through processes that do not emit carbon dioxide, essentially means using hydrogen as the ‘reducing agent’ (remover of oxygen) in steel production. In other words, iron ore is basically iron oxide and hydrogen is used to pull oxygen away from iron oxide, leaving pure iron behind—to which a little carbon is added to make steel. Right now, carbon, in the form of coke, has been used for pulling away oxygen; when carbon joins hands with oxygen it becomes carbon dioxide, which is today mankind’s greatest enemy. Hydrogen can do the job of coke just as well.
It now emerges that much of Indian iron ore is unsuitable for making green steel. According to Australia’s Commonwealth Industrial and Scientific Research Organization (CSIRO), which is te country’s publicly funded research organisation and an expert in mines and minerals, 66 per cent of India’s (and Australia’s) iron ore is not suitable for being made into green steel.
This is because Indian iron ore is low-grade. Low-grade iron ore can only be made into steel in blast furnaces—huge cooking pots in which iron ore is melted and made to combine with coke, before being poured into moulds for making steel slabs. For technical reasons, green steel making requires the ‘electric arc furnace’ route; EAFs need high-grade ores, in which iron content is over 60 per cent.
Challenging endeavour
Now, the question is: why hydrogen can’t just be injected into a blast furnace to do the same job as coke? This is theoretically possible, but there are two major problems.
First, blast furnaces need to operate at high temperatures, or the order of 1,000-1,200 degrees C. Combustion of hydrogen releases a lot less heat compared with the combustion of coke. Hydrogen must be pre-heatedto high temperatures to provide sufficient heat for the blast furnaces. Pre-heating hydrogen means using more energy, which must again come from renewable sources so that the steel qualifies for the ‘green’ label.
Second, use of hydrogen results in ‘embrittlement’ of iron, leading to cracks and fractures in the metal. To avoid this, you again need special alloys to resist hydrogen embrittlement.
Therefore, producing green steel in blast furnaces by injecting hydrogen as a replacement of coke is technically challenging and economically infeasible.
“Unlikely,” said Atanu Mukherjee, CEO and Managing Director of Dastur Energy, part of the Kolkata-based M N Dastur group, which has been a consultant for the steel industry for long, when asked if India would see green steel production any time soon.
He concurred with CSIRO that high-grade iron ore or steel scrap is needed for making steel through the EAF route—neither of which is available in India in the required quantities.
Indiahas invested tens of billions of dollars into creating blast furnace-based steel production, which is not suitable for producing green steel. Blast furnaces are big emitters of carbon dioxide. A blast furnace capable of producing 2 million tons of steel annually will emit at least 2.5 million tons of CO2 a year.
“There is currently no commercially available low-carbon steel-making route for a majority of Indian and Australian ores,” Keith Vining, a researcher at CSIRO, Perth, told a group of visiting Indian journalists last month.
In 2022, India produced 124.5 million tonnes of steel. The country produced 25.1 million tonnes of iron ore between April and December 2022.
Alternative technologies
Meanwhile, the search for alternative technologies continues. While green steel, using hydrogen, is hard in India, scientists are looking out for processes that can at least bring down CO2 emissions.
Prof Veena Sahajwalla, founding Director of the Centre for Sustainable Materials Researc & Technology at University of New South Wales, Sydney, is an expert in producing new generation green materials, primarily from waste.
She has told businessline that it is possible to reduce CO2 in blast furnaces to some extent by replacing a part of the coke with used automotive tyres. Apart from reducing dependence of coking coal, which India imports, these tyres contain about 7 per cent hydrogen, which helps.
The Indian Institute of Science, Bengaluru, is toying with the idea of replacing some of the coke with biochar.
Another interesting technology is under development at Tata Steel, about which businessline reported on February 4, 2020. This process, which the company has named HIsarna, is a “completely new technology” for steel making, capable of slashing CO2 emissions by 80 per cent compared with the blast furnace route. In a conventional blast furnace, a mixture of iron ore, coke and limestone – is put into the furnace and a blast of oxygen is sent in through a lance. Th mixture melts and collects at the bottom. In HIsarna, the ore is liquefied in a high-temperature cyclone at the top and the molten ore drips to the bottom of the reactor, where powder coal is injected.
“The technology removes a number of pre-processing steps and requires less stringent conditions on the quality of the raw materials used,” says a Tata Steel note on the technology. Since it is highly concentrated carbon dioxide that leaves the reactor, the system is “ideally suited for carbon capture and either storage (CCS) or use (CCU), without the need for a costly gas separation stage.”
HIsarna has been under development for nearly a decade. Asked for an update, a spokesperson of Tata Steel told businessline: “We are currently working on the HIsarna pilot facility in IJmuiden (The Netherlands) and depending on the relevant approvals we will soon embark on the next campaign.”
India-Australia Green Steel Initiative
In June 2021, the Indian and Australian governments formed an Idia-Australia Green Steel Partnership to work on a range of research, technology and commercialisation projects over a three-and-a-half year period to accelerate the steel making value chain in both the countries. CSIRO of Australia is working with a few Indian labs. For instance, it is working with the Institute of Minerals and Materials Technology (IMMT), Bhubhaneshwar, which is working on a plasma technology for “very rapid melting of iron oxide using hydrogen”.
In sum, there are technologies showing up on the horizon but the wait for them to become commercially available is likely to be long.
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Published on April 22, 2023
Related Topics
iron and steel
green technologies
