Steel Flows in the United States.

[NNadir]

The paper I'll discuss in this brief post is this one: Mapping the Annual Flow of Steel in the United States (Yongxian Zhu, Kyle Syndergaard and Daniel R. Cooper, Environ. Sci. Technol.2019, 53, 19, 11260-11268)

The production of steel is coal dependent, and all the hand waving and fantasies in the world about the death of coal will not change this fact in the immediate future. Personally I believe that it is technologically feasible to displace coal in steel making, but not using steel intensive industries like, say, the wind industry, although the effort to make it significant - which will fail because of the simple laws of physics - will uselessly consume a lot of steel for no good purpose.

From the paper's introduction, verifying the fact of the GHG intensity of steel:

The steel industry accounts for 30% of global industrial greenhouse gas emissions (GHG).(1) The Intergovernmental Panel on Climate Change (IPCC) recommends an overall 40–70% reduction in GHG emissions from 2010 levels by 2050.(2) However, with current best steel-making practices already approaching thermodynamic limits, even deployment of cutting-edge production technologies will not be enough for the steel industry to meet the IPCC’s emission targets.(3,4)

Realization that steel production must decrease if emission targets are to be achieved has helped lead to new research areas under the banners of “material efficiency”(5) and “circular economy”,(6) both aimed at reducing emission-intensive material production. Researchers in these new areas require a detailed material map in order to identify opportunities.

Unlike in the developing world, U.S. per capita steel stocks plateaued around 1980. The stock saturation level has been estimated at 9.1–14.3 t/capita.(7?9) Per capita stocks are expected to saturate in much of the developing world to a level similar to those in the U.S. by the late 21st century.(10,11) Therefore, the derived U.S. consumption pattern may represent a population-scaled surrogate model of the future global state.

I'll just cut to two of the informative graphics, one of which is a Sankey diagram of US steel flows, which, to utilize, one may need to utilize expanded views and rotation tools:



The caption:

Figure 2. Formally reconciled U.S. flow of iron and steel (including embedded alloying elements) in 2014. Drawn using eSankey software.(59)

The caption:

Figure 3. Low-resolution U.S. steel map for 2014. U.S. population in 2014: 318.6 million.

It is notable that the United States throws away more steel than it produces from pig iron and that amount of steel consumed for transportation is double that of the rest of the world, even if we love to declare ourselves "green" in contrast to say, China:

U.S. scrap sent to landfill and export (34 Mt) exceeds carbon-intensive pig iron production (24 Mt) and intermediate steel product imports (29 Mt). On the face of it, increased domestic recycling could help to displace these carbon-intensive steel sources. However, a technical barrier to realizing this opportunity is contamination of EOL scrap with tramp elements, of which copper is the primary concern.(63) Daehn et al.(34) showed that copper contamination does not currently constrain global recycling rates. Their study highlighted that construction products, in particular, rebars (?0.4 wt %Cu), act as impurity sinks. In contrast, the cold-rolled sheet used mainly in transport applications has the strictest impurity requirements (?0.06 wt %Cu). The U.S. has a relatively large end-use transport sector—26% of final consumption in the U.S. (Figure 2) versus 13% globally(12)—and a small construction sector (38 vs 55% globally(12)). Moreover, the new steel map shows that just 21% of U.S. construction demand is for impurity-tolerant rebar, compared to 28% globally.(12) A smaller construction sector with less rebar means a smaller sink for scrap contaminants.

In a closed carbon cycle world, which I freely admit would be energy intensive, one can imagine the separation of impurities like copper might be conceivable.

Interesting paper, I think.

I trust you're having a wonderful afternoon.

[underpants]

1. 👀 fascinating

Bookmarking to read later.