TB: How the World Really Works (Smil)

Core Thesis

We are a fossil-fueled civilization. Our technical advances, quality of life, and prosperity rest on the combustion of fossil carbon, and we cannot simply walk away from this in a few decades. The prescription "just decarbonize" ignores four material pillars of modern civilization — ammonia, steel, concrete, and plastics — none of which have affordable fossil-free production routes. Energy literacy is prerequisite to understanding the modern world; without it, even intelligent people talk about the future in ways that are disconnected from physical reality.

Key Takeaways

The four pillars of modern civilization

Ammonia (fertilizers), steel, concrete, and plastics are the foundations of the modern world.
None of these can currently be produced at scale without fossil fuels. Decarbonizing electricity is plausible; decarbonizing these four is a fundamentally different challenge.
There is no affordable mass-scale alternative for trucking, aviation, shipping, or iron smelting.

Energy is the only truly universal currency

Any process can be defined as a sequence of energy conversions. The economic system is essentially a system for extracting, processing, and transforming energy.
Modern economics has largely ignored energy. This is why most economic forecasts about the energy transition are untrustworthy.
Understanding how the world works requires energy literacy first.

We are more dependent on fossil fuels than ever

High-energy societies have been steadily increasing their dependence on fossil fuels and on electricity.
Producing food requires substantial direct and indirect fossil fuel inputs. It would be very difficult to run field machinery without liquid fuels or to produce fertilizers without natural gas.
Both the high relative share and the scale of our dependence on fossil carbon make any rapid substitution impossible. Even with abundant, reliable renewable electricity we would still need large-scale processes to make steel, ammonia, cement, and plastics.

Against extreme views

The book strongly advocates against extreme positions — both techno-optimism ("we'll solve it in a decade") and collapse pessimism ("civilization will end").
We have real choices and real constraints. Pretending otherwise in either direction is not helpful.

Energy transitions are slow

Every transition to a new energy supply must be powered by the intensive deployment of existing energies.
Solar PV and wind turbines are embodiments of fossil energies — built using fossil fuel energy, steel, concrete, and plastics.
Electricity supplies only ~20% of final global energy consumption. Of electricity generation: nuclear fission ~10%, hydro ~16%, solar ~7%, the rest from coal and natural gas.
At 2020 production levels, coal reserves would last ~120 more years, oil and gas about 50.

Understanding food: we eat transformed fossil fuels

We have always eaten the products of photosynthesis, energized by solar radiation (the blue and red parts of the visible spectrum). Photosynthesis combines atmospheric CO2 and water — plus small amounts of nitrogen and phosphorus — into new plant mass.
What has changed is the intensity of crop and animal production. Such abundance, in such a predictable manner, is impossible without rising inputs of fossil fuels and electricity. Direct inputs: fuel for field machinery, harvest transport, irrigation pumps. Indirect inputs (far broader): fertilizers.
The road to the modern world began with inexpensive steel plows and inorganic fertilizers. In two centuries the human labor to produce a kilogram of American wheat fell from 10 minutes to under 2 seconds; between 1800 and 2020 the labor per kg of grain dropped more than 98%, and the agricultural share of the population fell by the same margin.
The three macro-nutrients are nitrogen, phosphorus, and potassium (NPK). Potassium is cheapest (potash, KCl, from mines). Nitrogen is the crux.

The nitrogen paradox and Haber-Bosch

Nitrogen is in every living cell — in chlorophyll, in DNA/RNA, in the amino acids of all proteins — and is needed in large quantities. Yet though it makes up ~80% of the atmosphere, it is a key limiting factor in crop and human growth. The paradox: atmospheric nitrogen is the non-reactive molecule N2, and only a few natural processes can split that bond to make the element available as reactive compounds.
Ammonia (NH3) is the highly reactive starting compound for all synthetic nitrogenous fertilizers — the most important indirect energy input in modern farming — readily converted into soluble nitrates plants can use. Its synthesis depends heavily on natural gas as the source of hydrogen.
The Haber-Bosch process (invented at BASF) is how ammonia is made — "easily the most momentous technical advance in history." Natural gas as the hydrogen source was the key innovation behind the Green Revolution. ~150 megatons of ammonia are now synthesized annually, ~80% used as fertilizer. In 2020, nearly 4 billion people would not have been alive without synthetic ammonia, which is why Smil ranks it the most important of the four pillars.
Half of recent global crop harvests have been produced thanks to synthetic nitrogenous compounds. Leguminous crops (soybeans, beans, peas, lentils, peanuts) fix their own nitrogen, but no staple grain, oil crop, or tuber can. A "nearly perfect solution" would be grain/oil crops whose roots host nitrogen-fixing bacteria.

Meat and feeding efficiency

Feeding efficiency over five decades has not improved for beef or pork, but has improved impressively for chicken. One American chicken (~1 kg edible) needs ~3 kg of corn; total energy is 300–350 mL diesel-equivalent per kg, remarkably efficient versus 210–250 mL/kg for bread — which helps explain chicken's rise to dominant meat in the West.
Capturing seafood is the most energy-intensive form of food provision: preferred marine species are carnivorous and must be fed protein-rich fish meal and oil.
Mass-scale veganism is "doomed to fail" — meat-eating is as significant a part of our evolutionary heritage as our large brains (which evolved partly because of it); all our hominid ancestors were omnivorous, as are both chimpanzee species.
Anthropogenic energy inputs to field farming total only ~4% of annual global energy use — small inputs with disproportionately large consequences (the Sun does most of the work). For the US, total energy in food production is ~20% of the total energy supply.
"Industrial man no longer eats potatoes made from solar energy; now he eats potatoes partly made of oil." Even changing the food system as fast as realistically conceivable, "we will be eating transformed fossil fuels for decades to come." For now and the foreseeable future, we cannot feed the world without fossil fuels.

Materials: the four pillars in detail

The four pillars (ammonia, steel, concrete/cement, plastics) are needed in larger and still-increasing quantities than other inputs and are not replaceable by other materials. Their mass-scale production depends heavily on fossil fuel combustion, some of which also supplies feedstocks. Global production of the four claims 17% of the world's primary energy supply and 25% of all CO2 emissions.
Steel: made from cast (pig) iron — 95–97% iron, 2–4% carbon (the carbon makes it brittle) — by reducing carbon to 0.08–2%. Iron ore smelting needs coke made from coal. Steel beats the hardest stones and the other common metals on physical properties (granite's tensile strength is an order of magnitude lower). It dominates the look of modern civilization, is the largest part of most transportation equipment (jetliners excepted — aluminum alloys and composites), and steel containers ship nearly everything. Only oxygen, silicon, and aluminum are more common in the crust. Recycled steel is ~30% of annual output; total energy requirement ~5% of the total energy supply.
Cement and concrete: cement is much less energy-intensive per ton than steel, but its global output is ~3x larger, so its production yields a similar carbon output. Cement is made by heating ground limestone (calcium) plus clay/shale (silicon, aluminum, iron) in large kilns. Concrete is 65–85% aggregates plus 15–20% water, held together by cement (~10% of final mass). It is the most massively deployed material of modern civilization — good in compression, and good in tension when steel-reinforced.
Plastics: a large group of synthetic organic materials fit for molding. Synthesis starts with monomers bonded into polymer chains/branches; two key monomers — ethylene and propylene — come from steam cracking (heating to ~800°C) hydrocarbon feedstocks derived from crude oil and natural gas. PVC is the primary component of 25% of all health-care products. Irresponsible dumping is not an argument against proper use of these often-indispensable materials.

Microchips, transport, and globalization

We could have an accomplished, reasonably affluent civilization with plenty of food, comfort, and health care without any semiconductors, microchips, or PCs — we had one until the mid-1950s. Producing large high-purity silicon crystals costs two orders of magnitude more primary energy than aluminum and three orders more than steel.
Microchip progress: in 1996 Penn students recreated ENIAC on a 7.5 × 5.3 mm chip (175,000 transistors); the original was 5e6 times heavier, used ~4e5 times more electricity, and was 5e2 times slower. Between 1971 and 2019 microprocessor power rose by seven orders of magnitude (~17e9 times).
Globalization / China: if low labor cost were the sole driver, sub-Saharan Africa or India would beat China. China won by combining a centralized one-party government guaranteeing political stability and acceptable investment conditions, a large, homogeneous, literate population, and an enormous domestic market.
Diesel engines made the greatest difference in enabling mass-scale transport in the global economy. The greatest shipping innovation came in 1957 with the standardized uniformly-sized steel cargo container. Gas turbines spray fuel into compressed air to make a high-temperature gas that expands and exits at high speed. Natural gas is cleaner than coal or refined oils and well suited to industrial, domestic, and electricity uses. There can be no natural-gas or coal powered flight: methane's energy density is three orders of magnitude below aviation kerosene, and coal would not flow from wing tanks.

Understanding risk

Modern civilization can be seen as serial quests to reduce the risks of being complex, fragile organisms surviving in a world of dangers.
Driving is an order of magnitude more dangerous than flying; while driving, the average chance of dying goes up ~50% versus staying home. Skydiving is 50x more dangerous than sitting in a chair.
Widespread fear of nuclear electricity is an excellent example of risk misperception — France has drawn >70% of its electricity from nuclear fission since the 1980s; large nuclear reactors are the most reliable producers of electricity.
Viral pandemics are guaranteed to reappear with relatively high frequency. We can likely avoid 1918-scale mortality (TB eradicated, pneumonia treatable with antibiotics). ~1e9 people have lived through three pandemics, yet when COVID-19 struck references were overwhelmingly to 1918 — the three more recent pandemics left almost no impression. COVID's lesson: we were unprepared for an event whose near-imminent occurrence could have been forecast with 100% certainty.
Survival limits: oxygen is the most acutely limiting resource (the Great Oxidation event began ~2.5e9 years ago). No rehydration for a day is trying, for two perilous, after three usually fatal.

Environment and climate

Simple physics explains the worry about planetary warming. CO2 and CH4 are a negligibly small fraction of the atmosphere (which is ~80% N2, ~20% O2), but their effect makes the difference between a lifeless frozen planet and a blue-and-green Earth. Trace gases absorb some outgoing infrared radiation, raising surface temperature, which allows liquid water; its evaporation adds water vapor — itself a strong infrared absorber.
Water vapor is by far the most important absorber and has caused most past and future atmospheric warming — but it is not the cause, because it does not control atmospheric temperature. Earth's warming is controlled by trace gases whose concentration is not set by ambient temperature. Rising CO2 emissions come mainly from fossil-fuel combustion and cement production. CO2 accounts for ~75% of the anthropogenic warming effect, CH4 ~15%, the rest mostly N2O.
The nutrient corollary: the real worry about plant nutrients is their unwanted presence in the environment — phosphorus runoff from fertilizers causes algal blooms in waters that normally hold very little phosphorus.
We did not need new computer models or the IPCC to beware of the greenhouse effect. The only effective, substantial moves toward decarbonization have not come from deliberate targeted policy but as by-products of general technical advances (higher conversion efficiencies, more nuclear and hydro, less wasteful processing) and management shifts (coal to natural gas) undertaken for other reasons. Three decades of large-scale climate conferences have had no effect on the course of global CO2 emissions.
"To believe that our understanding of dynamic, multi-factorial realities … has reached the state of perfection is to mistake the science of global warming for the religion of climate change." No 1980 climate modeler predicted the most important anthropogenic driver of the past 30 years: the economic rise of China. All climate models should be seen as heuristic exercises — bases for thinking about options — never as prescient descriptions of the future.

The future

Realistic near-term steps exist: displace coal-fired electricity with natural gas and expanding solar/wind, move away from SUVs toward mass EV deployment, and reduce large inefficiencies in construction, household, and commercial energy use.
Any sufficiently effective action will be "decidedly non-magical, gradual, and costly." Non-carbon energies could fully displace fossil carbon in 1–3 decades only if affluent nations accepted substantial cuts to living standards and modernizing Asia/Africa were denied improvement.
Population is decisive: sometime in the 2020s half the world population will live in countries with below-replacement total fertility; few uncertain outcomes will matter more for our future than the 21st-century population trajectory. (A 1960 Science paper absurdly projected infinitely rapid growth by November 2026.)
Informed looks at the three existential necessities — breathing, drinking, eating — agree there should be no unavoidable apocalypse by 2030 or 2050. Steel, cement, ammonia, and plastics will endure as the four pillars; a major share of transport will still run on refined liquid fuels; grain fields will still be plowed by tractors.
On climate, no real progress is possible until at least the top 5 emitters — now responsible for 80% of all emissions — agree to clear, binding commitments. A common climate-economy model puts the break-even year for mitigation launched in the early 2020s only around 2080.

Mental Models

The Map is Not the Territory — "decarbonize" is a map that sounds simple; the territory includes ammonia, steel, concrete, plastics, shipping, aviation, and agriculture

Source note

How the World Really Works (Smil)