Amazon seems pretty happy with those Rivian delivery Vans. The thing with forklifts is that, when you use them in enclosed spaces (like say, a fullfillment center), ICEs are a big no-no, because the CO2 and CO can kill people.
So, your only options are either Electric forklifts or Hydrogen Forklifts. And guess what? Unlike the delivery vans, which can be carged overnight (because night deliveries are significantly fewer than daytime ones), Forklifts in a fullfillment center are used 24/7, so recharging time counts.
Hydrogen forklifts can be recharged in less than 5 min, Vs the hour or so of downtime for electric forklifts...
Even at reduced efficiency, If they can make the Hydrogen with clean energy (solar+Wind), is still clean.
A well known solution to the charging time problem is battery swapping. There are solvable but real issues with battery swapping "in the wild" but these don't really apply in this application.
- Batteries are heavy so moving them around requires something like a fork lift. Where are you going to find one of those in an Amazon warehouse? Oh, wait..
- Cars come in a wide range of shapes related to reducing aerodynamic drag. Working with those different ways to accessing differing shaped batteries is a real problem. Forklifts are shaped pretty much like bricks and Amazon has total control.
- "In the wild", batteries come from who knows who and there is a real risk that the owner of a brand new EV swaps his/her brand new battery for one that is about to die. In an Amazon warehouse, the forklifts are owned by Amazon and, well, that's all