Thanks for all the answers. 

I completely side with what florian said: to be able to offset the carbon footprint of goods assembled with parts coming from all over the planet is kind of mission impossible. So, let's buy things once and buy durable things. My car is now 17 years old, and still drives absolutely fine - it’s a bit of an ecosystem inside, but who cares it still gets me from A to B when required. 

As for module production… I blame myself when I switch on the modular, and think about the energy and minerals it required to come into life. That’s the price of western civilisation custom made entertainment.  

And for the PSU3: I only had a look at it because it’s go 5V. I might just go for the 5V adaptor for my PSU2 anyway. 

Another though, totally outside this group intended subject, is to the solar panels: it must be a while before you manage to offset the carbon footprint of their production (getting the Si crystals, the doping, the plasma slicing, etc…). 

Blabbering, Stop!! 

Thanks again for all the details.