Cement has the advantage of being a small fraction of the weight and volume of the finished product. You source your water, sand and gravel closer to the work site but ship in your cement, I think you’re still in pretty good shape from an overall footprint standpoint.

Of course they are now electrolytically strip mining the entire ocean floor…

True and interesting point - but if you're able to produce as cheaply to "push out" dirty competitors and still have a net saving when including transport, it would still make sense I suppose. Also, there are always relatively close sun intensive regions near major customers: mongolia / tibet china, north africa europe & middle east, the US has its own deserts...

also, transport is a minor fraction compared to the net saving

Absolutely, CO2 emissions from transport isn't much of an issue compared with the saving. Hopefully someone like Remora will crack that problem anyhow. We'll most likely need to build our plants closer to where the market is though, to limit the financial cost of transportation

This kind of scale would require establishing factories all over the world. Every feasible region in every developed country.

Yep! It'll be quite a journey to get there