How the World Really Works: A Scientist’s Guide to Our Past, Present and Future

by Vaclav Smil

The inertia of large, complex systems is due to their basic energetic and material demands—as well as the scale of their operations. Demands for energy and materials are constantly affected by the quest for higher efficiencies and for optimized production processes, but efficiency improvements and relative dematerialization have their physical limits, and advantages brought by new alternatives will have offsetting costs. Examples of such realities abound. Turning, once again, to two fundamental inputs, the theoretical minimum of primary energy needed to produce steel (combining blast furnace and basic oxygen furnace demands) is about 18 gigajoules per ton of hot metal, and ammonia cannot be synthesized from its elements with less than about 21 gigajoules per ton.32 One possible solution is to replace steel with aluminum. This lowers the mass of a specific design, but primary aluminum requires five to six times more energy to produce than primary steel, and it cannot be used in many applications that require steel’s much greater strength. The most radical way to cut energy costs and the environmental impact of nitrogen fertilizers is to reduce how much is used: that option is available to affluent countries with their excessive food supply and waste—but hundreds of millions of stunted children, mostly in Africa, need to drink more milk and eat more meat, and that protein can come only from substantially increasing the amount of nitrogen they use in cropping. Just to drive t...