Rio Tinto has kick-started the major task of decarbonising its vast Pilbara iron ore rail operations, agreeing to buy four battery-electric trains from US manufacturer Wabtec ahead of a “series” of green investments in the region in coming years.

Less than a week after rival Fortescue Metals Group revealed it had snapped up two battery-electric locomotives in partnership with Caterpillar, Rio will on Tuesday unveil the purchase of four 7-megawatt-hour FLXdrive locomotives from Wabtec. Wabtec is one of the mining giant’s long-time rail suppliers, which last year also struck a deal for the same trains with Gina Rinehart’s Roy Hill.