> Obviously, it is possibe to optimize something here and there, but if we compare with humans doing the same job, and the energy they would need, this must surely be less...?

The issue here is that the human needs the same amount of energy no matter what he's tasked with. Ideally robots will mean humans will be spending their time on fewer menial tasks, but the environmental impact of a living human is the same no matter if they're stocking shelves or doing any other job.

Robots might be able to give some environmental improvements in the workplace though. The areas they inhabit don't need to be well lit or heated/cooled for human comfort, but that's only true for places and times where humans can be removed entirely. Even in a fully automated warehouse the moment a repair person comes in, or a janitor, or a exterminator, or any human employee you have to accommodate their safety and comfort.

I suspect the additional efficiency of machines will just make it faster and easier for people to consume irresponsibility produced and packaged goods

I don't actually know! But there are a lot of factors. One is the movement of the robots, another is their construction and the supporting structure, as well as all the electronics involved. Making electronics is very resource-intensive.

I often wonder about how to make these kinds of comparisons, but it always involves so many guesstimates that it quickly falls apart.

I think you should compare it to what's normally being done for groceries. You would get a trailer of a good. Then in your warehouse split that into smaller pallets, going with other goods on a new trailer to a store. There, a worker would have to put the goods on the shelves, and a customer later pick it into their cart. The store also uses lots of resources. Same with every shopper in a neighborhood driving their own car to the store, vs a van delivering to multiple homes.

So I think it's better.

Oh, I understand that. It's still a lot of robots, but maybe it means less lorries and, ultimately, a whole layer of small shops and maybe secondary warehouses that aren't needed. Maybe it does add up to less fuel and less steel.

It also leads to a lot more centralization, but that's a different discussion, of course.