The poor round trip efficiency of hydrogen means that if there is power available it is far better to do anything else with it rather than convert excess power to hydrogen. If it can't be used right now then it is less wasteful to store it with pumped hydro, compressed air, thermal salt, gravity or any sort of battery than throw away 2/3rds of it on green hydrogen's awful RTE.
Green hydrogen may be suitable for replacing hydrocarbons in industrial processes or with international sea transport where there are no other options and deep financial pockets but for land transport where recharging is an option green hydrogen is just wasting perfectly good power. Brown hydrogen maybe an option for heavy land transport, I do not know how it stacks up economically but I would suspect that sticking with diesel would be the favoured path unless there are some very hefty carrots or equally nasty penalties brought in to encourage swapping to hydrogen.
On the other hand the Tesla Semi and most likely EV trucks from Volvo, Scania, Kenworth, Mack and others already have a competitive TCO and their main problem is lack of supply. Currently the established manufacturers are mainly promoting Class 6 and 7 body trucks instead of Class 8 prime movers as well but Janus, an Australian company is swapping out the drivetrain of used semis and replacing it with an electric one.
