Four Material Pillars

Do you want to know How the World Really Works? It’s the title of Vaclav Smil’s latest book. Unlike his previous tome that I read, this book is a brisk read. Each of the seven chapters begins with the word “Understanding…” and the seven things we should understand are (1) energy, (2) food production, (3) our material world, (4) globalization, (5) risks, (6) the environment, and (7) the future. Today’s blog post focuses on #3, subtitled “The Four Pillars of Modern Civilization”.

 

Smil grounds his data analysis in quantifying energy; I find this particularly appealing as a physical chemist. While most of the twitter and chatter of our modern world focuses on the internet-web-cloud that is based on silicon, Smil argues (convincingly) that this isn’t a crucial pillar. As physical beings, with physical needs (food being foremost!), what has built modern human society are the following four pillars (in alphabetical order): ammonia, cement, plastics, steel.

 

Ammonia feeds the world. Smil’s analysis shows that without synthetic ammonia for fertilizer, we would not be able to feed half the present world’s population of 8 billion people. Globally there is actually a surplus of food, but it is not distributed equally. Rich countries waste food, poor countries need more of it. Why is ammonia crucial? Because we need nitrogen, a key component in proteins and nucleic acids. There’s plenty of nitrogen in our atmosphere in the form of N₂ gas. But most living things can’t use it because of the very strong triple bond between the nitrogen atoms that make N₂ an inert gas. Some bacteria can “fix” this nitrogen, but only in a limited number of crops, mostly legumes. Manure or wood ash also provide nitrogen, but you’ll need heaps of it to cultivate crops on a large scale.

 

Enter the Haber process: N₂ + 3 H₂ à 2 NH₃ (ammonia). Students in chemistry classes see this example repeatedly because it’s useful for exercises in stoichiometry and equilibria, and discussing catalysis. 80% of ammonia produced is used for fertilizer, but ammonia is a gas, so spraying the gas on your field does you no good. Solubilizing it in water can work, but there’s also an issue with runoff. The dominant useful form is as solid urea, although ammonium salts are also used. The tough part about making ammonia: What’s your source of H₂? Right now it’s natural gas in the steam-methane reforming process. That’s an energy-intensive process, so we’re not weaning ourselves off hydrocarbon fuels anytime soon.

 

Concrete has gotten attention recently because it is a significant contributor to rising CO₂ levels in the atmosphere. Why? You need high temperatures and fuel to make it. And we make lots of it – billions of tons per year. It’s a bedrock of construction. Not just for tall urban buildings but for large sewer pipes, subway foundations, airport runways, bridges, sidewalks. You need something that’s strong, durable, and relatively cheap to make from sand, rock, and water? Concrete is what you want. The Pantheon in Rome, constructed two thousand years ago, still stands today. The “Roman cement” was made using gypsum (mostly CaSO₄), quicklime (mostly CaO), and volcanic sand (mostly SiO₂).

 

Plastic is amazing. While we easily identify its presence in plastic bags and Tupperware, the range of plastics we utilize today is staggering. It’s lightweight, durable, and can easily be shaped and tuned to whatever properties you need! Pipes, fabrics, plexiglass, rubber, insulation, packaging foam, adhesives, optical lenses, liquid crystal polymers, Kevlar, upholstery, the keys on your laptop, hospital feeding/IV tubes, toys, office supplies, and your credit card. Where do plastics come from? Petroleum materials, hydrocarbons, fossil fuels. I’m not sure much of modern society can live without plastic; it would be a very hard transition into a plastic-less world.

 

Steel is a partner to concrete in many of our large-scale engineering wonders today, but it is also used ubiquitously in smaller items: tools, cutlery, pots and pans, small appliances, ground-based vehicles, cargo containers, and most unfortunately, weapons. Steel is mostly iron, with some carbon and silicon, but as you can imagine, is also energy-intensive to make. We’re also making billions of tons. And yes, it’s also contributing to the rising CO₂ levels in our atmosphere.

 

You can sense a trend here. With climate change politics focusing on CO₂ levels and fossil fuel use, and the search for alternative “renewable” energy resources, carbon has gotten a bad rap. Smil makes the argument that we aren’t going to move away from hydrocarbons anytime soon, certainly not in a very big way, because it is underpinned by energy usage. Electrifying vehicles and making/recharging batteries is also energy-intensive and that energy has to come from somewhere. There’s no free lunch. Not to mention that you need physical materials to power the virtual world run on electricity. This is sobering but true. I know I personally would not want to go back and live in pre-industrial times. Unless you were a monarch or a rich nobleperson, life was subsistence and probably quite miserable – although you might not realize it if a subsistence life is all you ever know and you never see anyone in a different situation. Not to mention, there’s no way to support billions of humans on the planet. For both good and ill, we have transformed our world with modern materials and there’s no turning back.