In reading Smil, one thing to keep is mind is establishing the foundational assessments that may hold going forward (Hanson).
- Hanson assumes that existing social patterns of activity have robust explanations, so they will continue.
Chapter 2 is about the transition from foraging to agriculture and why this may have happened. From an energetics point of view it’s not totally explained because the net energy return was pretty high in comparison to agriculture.
In practice, essentially any iron alloy with less than 2% carbon gets referred to as steel
Why steel is so ubiquitous
- Useful material properties.
- Cheap to make.
Today there are over 3500 grades of steel which have a broad range of mechanical properties, but in general steels have both high strength (in both tension and compression) and high toughness (absorbing a lot of energy before rupturing).
Steel was used for a long time and considered a really good material due to it’s ability to maintain its shape after blows when compared with iron. It required high costs to make though.
Steel was made by initially combining iron and charcoal (which underwent pyrolysis) to diffuse carbon into the iron ore. The carbon content of the steel was then acheived by beating out the ‘slag’ (?).
- A single kg of iron required 6kg of iron ore and 15 kg of charcoal (105kg of wood).
- Turning this kg of iron into steel required another 20 kg of charcoal (140kg of wood).
- ~250kg of wood for a kg of steel (w/ denisty of 500kg/m3 specific gravity of 0.5 ~0.5m3).
- Annual production of steel in US is 86Mt/year. So you’d need 50m3/t, 4.3Gm3.
- The labour required to make charcoal for a tonne of steel is ~1000 days.
Heat rises with the cubed of the volume and the square of the surface area. Bigger blast furnaces produced more heat but scaled up heat losses.
David Shapiro talks about why one might still be experiencing cognitive dissonance with an issue.
- Looking at assumptions.
- Do I have all the facts.
- Do I have all the models and frameworks.