Aurizon's statements that it's already in talks with manufacturers and other rail operators regarding battery and hydrogen prototype models points to at least one option Aurizon could be looking at. Progress Rail's Brazilian plant has just rolled out a metre gauge battery locomotive, trademarked as the EMD Joule, as a yard shunter for iron ore giant Vale. Like Aurizon, Vale has also announced plans to be carbon neutral by 2050. The Joule can produce 3,000hp and carries 1.9MW of lithium ion batteries with a possible upgrade to 2.4MW. At maximum power that's about 45-minutes running time - but Progress expects 24-hours between charging based on the expected power demands during shunting.
What is interesting about the Joule is that it has been built to EMD's narrow gauge export model kinematic envelope, opening the design up for use in Queensland either as a new build or using locally sourced 2170, 2300, 2300D and 2470 Aurizon cores.
Not that Aurizon has much use for a traditional shunting locomotive, a handful could probably replace the 2470s currently used in Queensland yards, but some shorthauls and transfers in Queensland and Western Australia might be a fit.
They could likely also be used as rechargeable slugs in conventional diesel or electric consists to reduce emissions when the conventional locomotives need more power and then charge when power demand is lower - offering a quick way of reducing emissions while new locomotive technologies are still being developed. In this scenario the larger 2800 and 3551 class bodies might also make useful rebuild cores.
With Aurizon expecting prototypes to be running by 2025 there's not a lot of lead time and the Joule is probably more advanced on the time scale than other freight locomotive options suitable for narrow gauge.https://im-mining.com/2020/09/16/vales-100-battery-powered-mine-loco-starts-test-work-tubarao-complex/https://dieselprogress.com/cats-electric-locomotive-33878/https://youtu.be/v2DUWkHdsbw