Explainer: Why char, not coal, for Port Kembla steelmaking?

Why charcoal and is it good for the environment?

Blast furnace steelmaking requires large quantities of carbon, to be combined with iron to make steel. This carbon content is usually supplied by black or "metallurgical" coal, the type that is mined in the Illawarra and some parts of Queensland.

BlueScope's application says char, or biochar, can provide the carbon required at roughly the same ratio as pulverised coal as they have a similar "calorific content". About 1.1 tonne of char can do the job of 1 tonne of coal. But only small quantities are being trialled.

Read more: The early barrier to biochar production in Australia

Is it 'green steel'?

It's a shade greener. The use of biochar instead of some coal in blast furnaces would not have the same impact as changing to low-emissions techniques such as an electric arc furnace of hydrogen steelmaking. But BlueScope says these technologies are many years off being commercially viable, so this is a start.

Char could provide a source of carbon that is less greenhouse intense than coal, in its production, and in its acquisition - coal mines leak large quantities of methane which is highly greenhouse intense. Using char would also mean the environmental impacts of coal mining, such as water catchment subsidence, could be avoided.

But if the char is obtained from burning virgin forest to feed into a blast furnace, it would hardly be a greener solution. So ...

Where does the charcoal come from?

BlueScope said all the material for this trial will come from waste timber. It is being obtained from two sources in Australia, which make the char from building and construction waste, plus waste timbers such as pallets.

To make it, organic matter is fed into a kiln with little to no oxygen in a process called pyrolysis, which produces gas, oil and a solid material called biochar. The problem for larger-scale usage is where to get massive quantities of it.

Who's funding this?

This project kicked off after the Australian Renewable Energy Agency (ARENA) earlier this year gave BlueScope and the University of Wollongong more than $900,000 to investigate lower-carbon steelmaking technologies - approximately half of the cost of this project.

What is UOW's role?

Pilot trials will be conducted at the Bulk Materials Engineering test facility at UOW. After this, plant trials will be conducted at the Port Kembla steelworks, where different ratios of biochar will be mixed with pulverised coal, conveyed to the No.5 Blast Furnace, and injected into the mix.