I wrote:
> 2. The total mass of coal needed to replace steel this would be much less > than the mass of coal we now burn. I estimate it would be roughly 1/5th. > World production of steel is 135 million tons per month or 1.620 billion > tons per year . . . > I realize that is a silly analysis. We are not going to replace every ton of steel with carbon filament. In many cases it would be a bad choice of materials. You would not want carbon filament manhole covers. Most of the steel we replace would be used in transportation, making automobiles, trucks and railroad trains. I do not know what fraction of total steel production that is. Forbes tells me automobile manufacturing consumes 12% of steel: http://www.forbes.com/sites/greatspeculations/2015/05/20/trends-in-steel-usage-in-the-automotive-industry/#65264c677865 So, let us say carbon replaces 30% of steel, including cars, railroad cars, bridges, and other applications that would benefit from a lightweight, stronger replacement for steel. To replace that much steel with an equivalent mass of coal (ignoring the fact that carbon fiber is lighter) it would take 6% of the mass of coal we now mine. That will not save the industry or preserve employment. - Jed
