EnergyAndCivilization

Energy and Civilization (Vaclav Smil)

  • Learned a lot. Repetitive and boring at times.
  • Energy is the only universal currency: one of its many forms must be transformed to get anything done.
  • From a fundamental biophysical perspective, both prehistoric human evolution and the course of history can be seen as the quest for controlling greater stores and flows of more concentrated and more versatile forms of energy and converting them in more affordable ways into heat, light, and motion.
  • Only a tiny part of the the incoming radiant energy, less than 0.05% is transformed into photosynthesis into stores of chemical energy.

  • One C is the amount of heat needed to raise the temperature of 1 cc of water by 1 C. One C is ~4 J. For most moderately active adult need 2-2.7 Mcal or 8-11 MJ (10MJ could be supplied by eating 1 kg of whole wheat bread) Consuming 8 MJ of food a day corresponds to a power rate of 90W, light less than the the rating of a standard light bulb (100 W). A double toaster needs 1kW; small cars deliver 50kW; a large power plant produces electricity at 2 GW.

    Hard work will raise the daily energy need by ~30%. Book assumes 2MJ/day in approximate calculation of the daily expenditures in traditional farming and industrial work.

    Efficiency of steady aerobic performance is ~20% and this means that 20MJ/day of metabolic energy attributable to a physical task would produce 400kJ/day of useful work.

  • The power density of sustainable annual tree growth in temperate climates is at best 2% of the power density of energy consumption for traditional urban heating, cooking and manufacturing. This cities had to draw on nearby areas at least 30 times their size for fuel supply. This greatly restricted their growth even where other resources, eg: food and water, were adequate.
  • A real understanding of history requires much more than reducing everything to numerical accounts in J and W and treating them as all encompassing explanations.
  • Human bipedalism and ability to sweat better than any other mammal made it possible to chase to exhaustion even the fastest herbivores.
  • Only grains combine fairly high yields with high shares of easily digestible carbs and a moderate level of proteins Their moisture content when dried is low enough to allow long-term storage. Staple grains mature fast 100-150 days.
  • Traditional agriculture's could support population densities that were an order of magnitude larger than foraging societies.
  • Productive limits on traditional agricultures were removed only by rising inputs of fossil fuels, an energy subsidy that reduced agricultural labor to only a small fraction of the total labor force and enabled the rise of modern high-energy urban societies.
  • Without sickle and plow there would be no cathedrals or no European voyages of discovery.
  • The shift from foraging to farming left a clear physical record in our bones. A decrease in bending strength of leg bones and the population shifted to an increasingly sedentary lifestyle. This process was complete about 2e3 years ago, and there as been no further decline in bone strength since then.
  • Plowing prepares the ground for seeding much more thoroughly than hoeing: it breaks up compacted soil, uproots weeds, and provides loosened, well-aerates ground in which seedlings can germinate and thrive.
  • The water content of freshly harvested tubers is too high for long-term storage in absence of temperature and humidity controls.
  • Dependence on cereal grains is a matter of clear energy advantages. In terms of total energy content, all cereals are remarkably similar. The bulk of cereals food energy is in carbs.
  • Proteins have the same energy density as carbs, but their primary role in human nutrition is not as a source of energy but as a provider of 9 essential amino acids whole ingestion is essential to build and repair body tissues.
  • The quest for high yields needed three essential advances:
    • replacement of human work by animal labor
    • irrigation and fertilization
    • growing a greater variety of crops.

  • A horse's leg anatomy gives the animal a unique advantage by virtually eliminating the energy costs of standing. Can "lock" the limb without engaging muscles allowing the animals to rest even doze while standing.

    All other animals need 10% more energy when standing compared to lying down.

  • The water demand of crops is commonly about 1e3 times then mass of harvested grain.
  • Atmospheric C02 and water supply carbon and hydrogen, the two elements forming the bulk of plant tissues as new carbohydrates. But other elements are necessary for photosynthesis (marconutrients and microneutrients) Micro: many including: iron , copper, sulfur, silica and calcium Marco: only 3: nitrogen, phosphorus, potassium (N,P,K) Nitrogen is by far the most important one: it is present it all enzymes and proteins and is the element to be most likely in short supply in cultivated soils Each kg of nitrogen will result in an additional production of about 10kg of grain
  • The organic fertilizer with the highest nitrogen content is guano, droppings of seabirds preserved in the dry climate of islands along the Peruvian coast.
  • By the time Egypt was supplying the Roman empire with surplus grain, the Chines (Han dynasty) had develop several tools and practices that Europe adopted only centuries or even millennium later. Iron moldbard plows, collar harness for horses, seed drills, and rotary winnowing fans.
  • Although heavier than wooden plows, iron plows created much less friction and could be pulled by a single animal.
  • No other dynastic period can compare with the Han in terms of fundamental changes in farming. Irrigation was the most important and lasting contribution.
  • Mayan society was developing gradually for a long time before the beginning of the Classic period (300 CE) Then, in one of the most enigmatic turns in world history, the classical Mayan society disintegrated and its population declined from about 3e6 during the 8C to 1e5 by the time of the Spanish conquest.
  • During the 1880s American coal consumption surpassed wood combustion.
  • In 1910 Americas farm horse herd required almost 25% of the country's cultivated land.
  • All traditional peasants behaved as gamblers. They tried to stay on the slim margins of food surplus too long, betting that weather would help to produce another fair harvest next year.
  • Animate labor and conversions of the kinetic energies of water and wind (by sails and mills) where the only prime movers in traditional societies before steam engines.
  • Simple mechanical devices: Give were widely used in the Old World: wheel and axle, lever, system of pulleys, wedge, endless screw
  • The Americas has no native wheels
  • Ten men working steadily would equal the power of one standard horse.
  • Windmills, barbed wire and railroads where the iconic artifacts that helped open up the Great Plains
  • Wood: Carbon accounts for 45% of the total mass. Oxygen: 40% Freshly cut hardwoods are typically 30% water. This woods burn inefficiently as a significant part of the heat goes into vaporizing released moisture. Charcoal (virtually pure carbon) contains only a trace of moisture, it was always preferred by those who could afford it.
  • In Western Europe, the Roman achievements in road building where surpassed only during the 19C, in the eastern regions on during the 20th.
  • The steam engine had actually expanded the deployment of horses; most railway shipments had to be collected and distributed by horse-drawn wagons. Horse drawn city traffic was largely displaced by electric streetcars, cars and buses.
  • The enormous variety of building styles and ornaments can be reduced to only four fundamental structural members: walls, columns, beams and arches. Only human labor, aided by a few simple tools, was able to create them from the three basic building materials of the preindustrial world: timer, stone and bricks.
  • Concrete is a mixture of cement, aggregates (sand, pebbles), water, and cement. Cement is produced in a high-temperature processing of finely ground mixture of lime, clay and metallic oxides.
  • The beginnings of all old high cultures are marked by the use of color (nonferrous) metals. Besides copper, early metallurgists also recognized tin (used to make bronze), iron, lead, mercury, and silver and gold. Only copper and iron were relatively abundant and possessed, especially when alloyed, great tensile strength and hardness. The combination of abundance and their properties made them the only two practical choices for the mass production of durable items. Copper and bronze dominate the first 2 millennia of recorded history, while iron and its alloys (an enormous variety of steels) are now dominant more than ever.
  • Copper tools and weapons bridged the stone and iron eras of human evolution. Smelting and casting copper became common after the middle of the 4th millennium BCE. From the beginning cooper was incorporated into bronze.
  • The replacement of copper and bronze by iron proceeded slowly. The extensive use of iron dates only to after 1400 BCE, and the metal became truly abundant only after 1000 BCE. The metal was never smelted by any new world society. Iron smelting was bound up with the large-scale production of charcoal. Irons melts at 1523C an unaided charcoal fire can reach 900C, but a forced air supply can raise its temperature close to 2000C. Charcoal thus fueled all iron ore smelting in every traditional society except China, which used coal.
  • Blast furnaces produce cast, or pig, iron an alloy with 1.5-5% carbon that cannot be directly forged or rolled. Its tensile strength is no higher than coppers, but it is 2-3x harder.
  • Only the use of coke allowed the US to become the worlds largest producer of pig iron. Coke: made by heating coal or oil in the absence of air
  • Like cast iron, steel is also an alloy, but one containing only between 0.15% and 1% of carbon and often also small amounts of other metals. Steel is superior to cast iron or to any copper alloys: the best tool steels have a tensile strength an order of magnitude higher than either copper or iron.
  • Unlike ordinary combustion, where oxygen must be drawn from the surrounding air, KNO3 readily provides its own oxygen, and the gunpowder rapidly produces a roughly 3000 fold expansion of its volume in gas.
  • Wind and water flows are almost immediate transformations of solar radiation.
  • The origin of fossil fuels are also in the transformation of solar radiation: peat and coals arose from the slow alteration of dead plants, hydrocarbons from more complex transformations of marine and single-celled phytoplankton. Pressure and head were the dominant transforming processes; they lasted at least a few thousand years for the youngest peat to as long as few hundreds of millions of year for hard coals. This origin dictates their high carbon content, which combined with low content of water and incombustible impurities, translates into high energy densities.
  • Bituminous (black) coals make up the bulk of solid fuel extraction. Because they always contain some ash and sulfur their combustion generates fly ash and SO2. Until after WWII these were two common sources of industrial and urban air pollution.
  • Every transition to a new form of energy supply has to be powered by the intensive deployment of existing energies and prime movers: the transition from wood to coal had to be energized by human muscles, coal combustion powered the development of oil and today's solar photo-voltaic cells and wind turbines are embodiments of fossil energies.
  • The last leading economy to accomplish the transition from phytomass to coal was Chine where the process was delayed by the endless 20C crises, including decades of Maoist economic mismanagement and the worlds largest Mao-made Great Famine and the inanely named Cultural Revolution.
  • The replacement of charcoal by metallurgical coke in pig iron smelting belongs undoubtedly to the greatest technical innovations of the modern era as it accomplished two fundamental changes: severing the industry's dependence on wood (and hence requiring furnace location in or near forested regions) and allowing much larger furnace capacities and thus a rapid increase in annual production.
  • Steam engines were the first new prime mover successfully introduced since the adoption of windmills, which preceded it by 800 years. The machine was the first practical, economic and reliable converter of coals chemical energy into mechanical energy, the first inanimate prime mover energized by fossil fuel.
  • Railway expansion was the main reason for the unprecedented demand for steel during the 2ND half of the 19C.
  • The ascendance of internal combustion engines was made possible by the availability of inexpensive liquid fuels refined from crude oil: they had higher energy density than coal, were cleaner to burn, and were easier to move and store, a combination that still makes them the best choice for transportation.
  • The American search for oil was motivated by finding a replacement for expensive whale oil rendered on ships from blubber of sperm whales. (Was first found in Western Pa)
  • Most of these discoveries were hydrocarbon fields containing both crude oil and associated natural gas, but gas was rarely used during the early days without compressors and steel pipes it could not be moved over long distances and was just vented.
  • In diesel engines fuel injected into the cylinder is ignited spontaneously by high temperatures generated by compression ratios of 14-24 compared to just 7-10 in the Otto cycle gas engines. This requires a higher engine mass and lower speed, but diesels are inherently more efficient
  • The two common impressions – that the 20C was dominated by oil, much as the 19C was dominated by coal – are both wrong: wood was the most important fuel before 1900 and the 20C was dominated by coal.
  • Using combined-cycles gas turbines has become a favored way of generating electricity. Large diesel engines have been the most economical choice for electricity generation in remote locations as well as for providing standby capacities.
  • The first US nuclear power station, Shippingport, in Pa, began operating in 1957
  • Nuclear energy is a "successful failure". Successful b/c in 2015 it supplied 10% of the worlds electricity, before the Chinese surge of coal it was 17%. Failure b/c its enormous early promise remains largely unfulfilled.
  • The world now consumes more fuel wood and charcoal than ever.
  • Scaling ethanol production to supply a significant share of the worlds liquid bio-fuels is delusional.
  • Photo-voltaic growth has not been a gradual, organic process but a promotion driven by government subsidies. Cloudy Germany produced nearly three times as much PV electricity as sunny Spain.
  • Modern civilization depends on extracting prodigious energy stores, depleting finite fossil fuels deposits that cannot be replenished even on time scales of orders of magnitude longer than the existence of our species.
  • No other energy use offers such a payback as higher crop yields resulting from the use of synthetic nitrogen: by spending roughly 1% of global energy, it is now possible to supply about half of the nutrient used annually by the worlds crops.
  • In 2013 the worldwide production of iron and steel required ~7% of the total worlds primary energy supply, making it the worlds largest energy-consuming industrial sector. This compares to 23% for all other industries 27% for transportation and 36% for residential use and services.
  • For millennia no mode of traveling on land was faster than riding a good horse. For centuries no conveyance was less tiring than a well0-spring coach. Railways removed these constants in a matter of years.
  • Great monopolies provided affordable and reliable service, but they were not great innovators: the classic black rotary-dial telephone was introduced in the early 1920s and remained the only choice for the next four decades.
  • The Persian Gulf basin is an unparalleled singularity: it has 12 of the worlds 15 largest oil fields, and in 2015 it contained about 65% of the worlds reserves of liquid oil. These riches explain the lasting interest in the regions stability.
  • The 19 9/11 hijackers had no weapons other than a few box cutters and the entire operation, including flight lessons cost less than 500k.
  • Human beings are now carrying out a large scale geophysical experiment of a kind that could not have happened in the past nor be reproduced in the future. With a few centuries we are returning to the atmosphere and oceans the concentrated organic carbon stored in sedimentary rocks over hundreds of millions of years.
  • There is no affordable mass-scale alternative available for transportation fuels, feed stocks, or iron smelting.
  • 10s of millions of people annually take intercontinental flights to generic beaches in order to acquire skin cancer faster.
  • B/c the earths rotation amounts to about 460 m/s on the equator, finding the longitude requires chronometers that would lose no more than a fraction of a second a week if the ship was to positioned with an error smaller than a couple of km after a journey of 2-3 months.
  • Most historians have had no use for energy as an essential explanatory variable.
  • Our inability to comprehend the behavior of complex and interdependent wholes makes any specific scenarios of distant futures mere speculation. In contrast outlining extremes is easy, as the visions of future range from dismal to ecstatic.

Backlinks