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

by Vaclav Smil

their economies, nor just another variable in intricate equations determining the evolution of

these interacting systems. Energy conversions are the very basis of life and evolution. Modern history can be seen as an unusually rapid sequence of transitions to new energy sources, and the moder...

Physicists were the first to recognize the fundamental importance of energy in human affairs. In 1886, Ludwig Boltzmann, one of the f...

free energy—energy available for conversions—as the Kampfobjekt (the o...

life, which is ultimately dependent on incoming ...

Erwin Schrödinger, winner of the Nobel Prize in Physics in 1933, summed up the basis of life: “What an organism feeds upon is negative entropy” (negative entropy or negentropy = free energy).

Alfred Lotka concluded that those organisms that best capture the available energy hold the evolutionary advantage.

“the economic system is essentially a system for extracting, processing and transforming energy as resources into energy embodied in products and services.”

Simply put, energy is the only truly universal currency, and nothing (from galactic rotations to ephemeral insect lives) can take place without its transformations.24

Modern economists do not get their rewards and awards for being preoccupied with energy, and modern societies become concerned about it only when the supply of any main commercial form of energy appears to be threatened and its prices soar.

We’ll see how different forms of energy (with their specific advantages and drawbacks) and different energy densities (energy stored per unit of mass or volume, critical for energy storage and portability) have affected different stages of economic development, and I’ll offer some

realistic appraisals of the challenges faced by the unfolding transition to societies relying less

and less on fossi...

The Greek etymology is clear. Aristotle, writing in his Metaphysics, combined ἐν (in) with ἔργνο (work) and concluded that every object is maintained by ἐνέργεια.

This understanding endowed all objects with the potential for action, motion, and change—not a bad characterization of a potential to be transformed into other forms, be it by lifting, throwing, or burning.

Little changed over the following two millennia. Eventually, Isaac Newton (1643–1727) laid down fundamental physical laws involving mass, force, and momentum, and his second law of motion made it possible to derive the basic energy units. Using modern scientific units, 1 joule is the force of 1 newton—that is, the mass of 1 kilogram accelerated by 1 m/s2 acting over a distance of 1 meter.27 But this definition refers only to kinetic (mechanical) energy, and it certainly does not provide an intuitive understanding of energy in all of its forms.

This led to what is still the most common definition of energy: “the capacity for doing work”—a definition valid only when the term “work” means not only some invested labor but,

one of the leading physicists of the era put it, a generalized physical “act of producing a

change of configuration in a system in opposition to a force which ...

the protean mind of Richard Feynman,

who (in his famous Lectures on Physics) tackled the challenge in his straightforward manner, stressing that “energy has a large number of different forms, and there is a formula for each one.

These are: gravitational energy, kinetic energy, heat energy, elastic energy, electrical energy, chemical energy, radiant en...

Electric cars are a common example of the first category: now readily available, the best models are quite reliable, but in 2020 they were still more expensive than similarly sized vehicles powered by internal combustion engines.

In terms of the second category, as I will detail in the next chapter, synthesis of the ammonia needed to produce nitrogenous fertilizers now depends heavily on natural gas as the source of hydrogen.

Hydrogen could be produced by the decomposition (electrolysis) of water instead, but this route remains nearly five times as expensive as when the element is derived from abundant and inexpensive methane—a...

The first law of thermodynamics states that no energy is ever lost during conversions: be that chemical to chemical when digesting food; chemical to mechanical when moving

muscles; chemical to thermal when burning natural gas;

thermal to mechanical when rotating a turbine; mechanical to electrical in a generator; or electrical to electromagnetic as light ...

However, all energy conversions eventually result in dissipated low-temperature heat: no energy has been lost, but its utility, its ability to perform useful work...

And back on land, large nuclear reactors are the most reliable producers of electricity: some of them now generate it 90–95 percent of the time, compared to about 45 percent for the best offshore wind turbines and 25 percent for photovoltaic cells in even the sunniest of climates—while Germany’s solar panels produce electricity only about 12 percent of the time.33

Another common mistake is to confuse energy with power, and this is done even more frequently. It betrays an ignorance of basic physics, and one that, regrettably, is not limited to lay usage.

Energy is a scalar, which in physics is a quantity described only by

its magnitude; volume, mass, density and time are other u...

Power measures energy per unit of time and hence it is a rate (in physics, a rate measures ...

Power equals energy divided by time: in scientific units, it is watts = joules/seconds.

Energy equals power multiplied by time: joules = watts × seconds.

Unfortunately, even engineering publications often write about a “power station generating 1,000 MW of electricity,” but that is impossible.

A generating station may have installed (rated) power of 1,000 megawatts—that is, it can produce electricity at that rate—but when doing so it would generate 1,000 megawatt-hours or (in basic scientific units) 3.6 trillion joules in an hour (1,000,000,000 watts × 3,600 seconds).

lying prone all day a 70-kilogram man would still need about 7 megajoules (80 × 24 × 3,600) of food energy, or about 1,650 kilocalories, to maintain his body temperature, energize his beating heart, and run myriad enzymatic reactions.

But liquid hydrocarbons refined from

crude oil (gasoline, aviation kerosene, diesel fuel, residual heavy oil) have the highest energy

densities of all commonly available fuels, and hence they are eminently s...

all modes of transp...

Here is a density ladder (all rates in gigajoules per ton): air-dried wood, 16; bituminous coal (depending on quality), 24–30; ...

In volume terms (all rates in gigajoules per cubic meter), energy densities are only about 10 for wood, 26 for good coal, 38 for kerosene. Natural gas (methane) contains only 35 ...

There could be no natural gas–powered flight, as the energy density of methane is three orders of magnitude lower than that of aviation kerosene, and also no coal-powered flight—the density difference is not that large, but coal would not flow from wing tanks to engines.

And the advantages of liquid fuels go far beyond high energy density. Unlike coal, crude oil is much easier to produce (no need to send miners underground or scar landscapes with large open pits), store (in tanks or underground—because of oil’s much higher energy density, any enclosed space can typically store 75 percent more energy as a liquid fuel than as coal), and

distribute (intercontinentally by tankers and by pipelines, the safest...

mass transfer), and hence it is readily avail...

Annual use of these compounds now surpasses 120 megatons (for comparison, global output of all edible oils, from olive to soybean, is now about 200 megatons a year),