Energy-intensive is fine, as long as the energy is renewable. Smelting aluminum and silicon or mining aluminum and iron ores with electricity produced by solar

Energy-intensive is fine, as long as the energy is renewable. Smelting aluminum and silicon or mining aluminum and iron ores with electricity produced by solar and wind is ideal: else that energy of light and air motion would be wasted. Steel and concrete are harder to produce in an emission-free ways, but steel smelting in arc furnaces is very much a thing, and can be powered by renewables, at least partly.