6 ideas
Smil argues that the energy density of a fuel or process sets hard ceilings on what economies can do. Fossil fuels store orders of magnitude more usable energy per kilogram than batteries or biomass, which is why substitution is slow and physical, not merely political.
He insists on comparing quantities by orders of magnitude rather than headlines. Framing a number against its baseline (a country's total energy use, global food output) exposes whether a claimed change is trivial or transformative.
Smil highlights four unglamorous pillars of modern life: ammonia, steel, concrete, and plastics. Synthetic ammonia fertilizer alone feeds roughly half of humanity, a dependency that decarbonization narratives routinely ignore.
He treats grand-transition timelines skeptically because infrastructure turnover takes decades. New technologies rarely displace incumbents at the pace pundits assume, since capital stock, supply chains, and physics all resist rapid replacement.
Smil repeatedly normalizes by population and time to separate genuine improvement from aggregate growth. A rising national total can hide stagnant or declining per-person outcomes, so the denominator carries the argument.
The book's short essays each rest on concrete cases rather than one central story, and one of them is Rudolf Diesel. He patented a compression-ignition engine in the early 1890s and built the first working version at Maschinenfabrik Augsburg (later MAN) in 1897, then vanished from the steamer Dresden while crossing the English Channel in 1913. Smil uses the case to show that Diesel's more efficient engine went on to power nearly all ocean freight, trucks, trains and farm machinery, making it an unnoticed backbone of global trade.