The new 8-axle locomotives will have an energy capacity of 14.5 megawatt hours and will be manufactured by Caterpillar subsidiary Progress Rail at its facility in Brazil.

"The purchase of these new battery powered locomotives marks an important milestone in the decarbonisation of Fortescue's locomotive fleet and demonstrates our commitment to achieving carbon neutrality for scope 1 and 2 emissions by 2030, as we diversify from a pure play iron ore producer to a green renewables and resources company," FMG CEO Elizabeth Gaines said.

"The new locomotives will cut our emissions while also reducing our fuel costs and our overall operational expense through lower maintenance spend.

"The acquisition builds on the work being carried out by Fortescue Future Industries' Green Team in Hazelmere to deliver locomotives operating solely on green ammonia and other green renewable fuels and technologies."

The first locomotive is expected to be delivered next year.