These rock-eating microbes could help make the global steelmaking industry carbon-free

Microbes can help decarbonize steelmaking: Australian miner BHP — the world’s largest miner — is looking into using rock-eating microbes to help cut emissions from steelmaking in what could be a major breakthrough in making the industry zero-carbon, Bloomberg reported last week.

Why old school DRI doesn’t work in Australia: Most steel made in coal furnaces can be refined using natural gas or hydrogen using the direct reduced iron (DRI) method, which reduces iron ore to iron without melting it. However, this process only works on high-quality iron ore, and most of BHP Group’s ore comes from Western Australia’s Pilbara region, where raw materials contain excessive impurities that need to be refined using anything other than coal.

By the numbers: Steelmaking produces c. 8% of global greenhouse gas emissions annually, according to the International Energy Agency (IEA). BHP is targeting a reduction of its Scope 3 emissions to net zero by 2050, a difficult task given that its emissions are equivalent to 365 mn tons of CO2 annually. This is about as much as the UK's annual emissions.

A golden opportunity: US-based biotech startup Allonnia discovered that BHP’s iron ore contains phosphorus-consuming organisms that can be used in a natural refining process, BHP Vice President Paul Perry said. “All living things eat phosphorus,” he said, but this specific microbe is believed to clear alumina from the ore.

Big potential: If such microbes are used on big stacks of iron ore, they could eat the redundant gunk — known as gangue — and make a product that can be used in most hydrogen-powered steel mills. This could allow the steelmaking industry to reach net-zero once the tech shifts to utility-scale operations.

Not the only one: BHP isn’t alone in its venture. Rio Tinto is looking into the use of biomass and microwave energy to process lower-grade ore. Fortescue Metals is also joining forces with Japan’s Mitsubishi and European steelmaker Voestalpine AG for a hydrogen-based pilot plant in Austria, which will test refining various grades of ore.