[jl6]

All true, but also remember that in a zero-fossil world the supply chain for solar/wind also needs to be decarbonized, which involves things like making green steel, which is not such a favorable efficiency story (the way to overcome it is simply to generate massive amounts of electricity cheap enough that you can eat the inefficiency).

[tialaramex]

I expect that a zero-fossil world does a lot more steel recycling. Today steel is insanely cheap. Not so very long ago steel was this wonder metal, too expensive to mass produce, and today the pennies most people don't want as change when buying things here have steel inside because no other metal would be cheap enough given the value of the coins. They're jacketed because people expect them to look like tarnished copper (they were once bronze coins), but copper is expensive compared to steel now so it's just a jacket around a steel core.

If steel went back to say, twice the price of bronze, I think recycling makes a lot more sense and that means far less need for new steel production.

[jl6]

Steel is cheap for two reasons: unaccounted externalities of the use of coal in the process, and massive scale. Coal-free steel is possible, but we don’t currently do it at scale, so there is work to do.

Recycling will make sense if steel becomes much more expensive, but a future with really expensive steel is not what we should be aiming for.

[pfdietz]

The issue holding back steel recycling is contamination, most notably with copper. This forces recycled steel to be "downcycled" into lower value uses like rebar, or the recycled metal to be diluted with freshly reduced metal. A means to remove copper from molten steel is needed; there are some ideas for this being pursued.

https://www.sciencedirect.com/science/article/abs/pii/S09213...

[tialaramex]

The externalities for burning coal to make steel aren't acceptable though, we would need the mythical high performance carbon capture solutions and those aren't materialising, everybody who promised more efficient solar did what they promised, bigger wind turbines, as promised, more compact storage, as promised - but the carbon capture is MIA.

[zahlman]

...Do we really need steel just to mount solar panels?

[jl6]

We need steel for a million and one things that make modernity possible, but in the context of renewable energy, we particularly need it to build the towers that the largest and most efficient wind turbines sit on.