In which years was energy generated?
The age of industry
For most of its history, mankind was dependent on muscle strength. Prehistoric hunters, gatherers and fishermen relied almost exclusively on the energy from their food. The effectiveness of muscle strength was increased early on by tools. With the invention of agriculture, humans also harnessed the muscle power of pets, and over time they also made use of mechanical energy - water mills, windmills and sailing boats were his most important inventions. The use of fossil fuels that ushered in the Industrial Revolution multiplied the amount of energy available to humans, but it also created entirely new problems.
Per capita energy consumption of hunters, gatherers and fishermen: Everyone uses
three to six times the human basal metabolic rate, especially food energy
and biomass as fuel. Own illustration.
Food is the first and most important source of energy for humans: We need the energy contained in food to keep us alive (“basal metabolic rate”) and to be able to do work (“performance metabolic rate”). The basal metabolic rate of a person is 55 to 90 watts - depending on weight and gender, although the values can fluctuate by over 30 percent depending on the individual. 55 to 90 watts, which corresponds to an energy consumption of 1.3 to 2.2 kilowatt hours per day (kWh / day). The power expenditure depends mainly on the muscle work and the ambient temperature. Heavy work can more than double your basal metabolic rate; Light physical work adds about 60 percent to the basal metabolic rate. The total energy turnover of a lightly working person is therefore 2.1 to 3.5 kWh / day (more on this: >> The energy turnover of people). We do not know whether this value also applies to early collectors, hunters and fishermen. But many researchers suspect that they only had to work >> little so that the value might fit. For historical reasons, the energy content of food is often given in calories; an average energy consumption of 2.8 kWh / day corresponds to 2,400 kcal or 10 MJ (the “official” SI unit). In the days of hunters and gatherers, these were mainly plants (parts), such as seeds, nuts, fruits and roots. Their energy content ranges from 1 MJ / kg for edible leaves to 15 MJ / kg for seeds and up to 25 MJ / kg for nuts. It was worth collecting; typically it produced ten to fifteen times as much energy as it cost in effort.
Hunting animals, on the other hand, required more effort than collecting plants - this was particularly worthwhile with large herbivores that had fatty meat. A large bison could contain 50 kilograms of fat, and fat is very high in energy at 39 MJ / kg. Human hunters concentrated on these animals, which they either chased individually to exhaustion or - especially with large animals or herds - hunted in groups. >> Better tools - such as the invention of the spear 400,000 years ago - made hunting easier and over time increased the amount of energy that was available in the form of meat. In some regions, >> fishing was even more productive than hunting: especially where large schools of fish migrated along the coast, this was extremely rewarding. The first permanent settlements of mankind emerged in such regions, and fishing allowed population densities of up to 100 people per square kilometer. Where people live in forests and from hunting, the food supply in prehistoric times usually allowed a maximum of ten people per square kilometer; In steppe regions, people came to a population density of around one person per square kilometer.
Another important source of energy already had Homo erectus tapped: the >> fire. With the fire he was able to expand his living space by areas that were previously too cold (even if only at night or in winter); Fire opened up a larger proportion of the energy contained in food - raw inedible parts could now be boiled, baked or fried. Humans convert more energy with the burned biomass than with food: the hunters and gatherers used a total of three to six times the basic human metabolism. With the fire, the profound transformation of the natural environment by humans began: Even the hunters and gatherers burned down forests in order to attract >> game hunting with the grasses that sprout afterwards. These were the first, quantitatively insignificant beginnings to use energy (in this case fire) to increase “production”; an application of energy that should determine the coming age of agriculture; the age in which people lived as hunters, gatherers and fishermen was energetically predominantly a "Regime of uncontrolled solar energy flows”(200): Humans lived on solar energy converted into biomass without controlling this conversion process.
Per capita energy consumption of agrarian societies: Everyone uses
18 to 24 times the human basal metabolic rate, especially food energy,
Biomass as fuel and, new: the energy of pets (but also of
Forced laborers and slaves). Own illustration.
With the >> invention of agriculture, the amount of available food energy increased because energy (in the form of human and animal labor) could be used to generate more energy (food). The harvests in Mesopotamia, the Nile, and northern China were enough for about 100 people per square kilometer of cultivated land. For so many people, however, the food was only sufficient if it was not fed to pets; and so they had to make do with leftovers that could not be used by humans or with pastures on unproductive land. This changed the composition of the food: It was again more dependent on the carbohydrates from plant food, the proportion of animal food fell, and with it the proportion of fats and proteins. People who made a living from agriculture were often smaller than previously the hunters and gatherers - an indicator of poorer nutrition; and they were exposed to famine when harvests failed (>> more).
In the course of time >> the yield of agriculture gradually increased; Higher-yielding varieties and better knowledge always allowed per square kilometer of cultivated land - albeit essentially vegetarian. Ha more people live from agriculture - in China of the Qing dynasty up to 500 men’s cup obstacles to higher production at that time were nutrient, especially nitrogen, deficiency and a lack of energy. Since animals were tamed (>> here), besides human drudgery, domestic animals have become the most important source of energy in agriculture and also for the transport of goods. But the sturdy horses competed directly with humans for food; For a long time, oxen and cows were preferred, which could use cellulose as ruminants, i.e. could live on grass stubble and straw. An ox with 300 watts did about the work of four people; and he provided meat and leather. Oxen could also pull plows: while people with hoes could prepare a hectare of land for sowing in around 200 working hours, an ox with a wooden plow only needed around 13 hours - that is, 15 times faster. The more demanding horse, which needed 1.5 to 2 hectares of forage area per animal, was only used increasingly as a draft animal with the invention and spread of the collar from the 12th century onwards; in southern Europe, the more undemanding donkeys and mules were preferred.
Human labor has been used in much of the world in the form of forced labor; be it as slave labor or in the form of dependent tenants and farm workers. The work in the fields is not equally intense all year round, and the labor of humans and animals was also used by the >> newly emerging states: The vast majority of monuments from prehistory, from the Great Canal in China to the pyramids in Egypt, were also based on forced and slave labor. Slaves enabled the citizens of Athens to devote themselves to the “polis” and did the heavy lifting in Rome; Only with the scarcity of slave labor towards the end of the Roman Empire were mechanical energy sources such as water wheels increasingly used.
Warmth, lighting and transportation
The Heat demand for cooking, for heating the houses and the production of bricks as well as for smelting iron was covered with biomass. In addition to plant remains such as straw, animal excrement was also used as fuel; By far the most important fuel, however, was wood. Where there was no forest, it was transported from far away. The energy consumption of a pre-industrial city is estimated at around 10 to 30 watts per square meter of built-up area, depending on the climate and the existing trades; In order to meet this energy demand sustainably with wood, at least 50 to 150 times the area of the city was required. (Even if the use of wood was not necessarily sustainable in the past: pre-industrial megacities would have been impossible for reasons of energy supply.) Wood was also used as a building material; Dozens of oak trees were required for a medieval house - over 4,000 for magnificent buildings like Windsor Castle in the 14th century; and also the construction of the sailing ships, which were increasingly used in the Middle Ages, consumed large amounts of wood - a ship suitable for the ocean with up to 3,000 oaks. So there was always a lack of wood; especially when the smelting of iron increased - about 1,000 tons of wood were needed to produce one ton of iron. As a result, there was a lack of wood in northern China as early as the 11th and 12th centuries, in England from the 13th century and in continental Europe from the 15th and 16th centuries - the forest here was up from AD 400 to AD 1600 from 90 20 percent of the total area has decreased. For example, due to a lack of firewood for drying salt, England had to import salt from France; the lack of wood also meant that the coal, which was actually unpopular, was >> burned. American iron making devoured 2,500 square kilometers of forest in 1810; a century later, the demand would have been 170,000 square kilometers (would have, because this demand could only be met by coal, which in 1910 already covered three quarters of the American energy supply).
Initially, open fires were also used lighting of the houses, later clay lamps were used in which animal fat (>> whale oil) and later also vegetable oil were burned. Candles were used from the year 800 BC. Incidentally, the efficiency of the energy conversion into light was only 0.01 (candles) to 0.03 percent (oil lamps).
The transport of food, fuel and goods, oxen and horses were the most common means of handling; in North Africa, the Middle East and Asia also from camels and in Tibet from yaks. Because of poor roads, wagons had a hard time, and after the collapse of the Roman road network, wagon transport declined again. In the days of the Romans, a cart pulled by oxen could pull 490 kilos of goods 15 to 20 kilometers a day. With the collapse of the roads, the importance of horses increased; in 1901 there were over 300,000 horses in London alone. Their diet (and the disposal of horse droppings) were a central issue in all large cities at that time. Transport on the water was cheaper and more efficient. Sails can be seen on Egyptian tomb paintings and Greek vessels, they were further developed by the Chinese and Arabs. Only in the late Middle Ages did Europe catch up and learn to sail close to the wind - together with the iron weapons one of the prerequisites for the >> conquest of the world, which was characterized by Columbus' Atlantic crossing and Magellan's Pacific crossing. Their ships were still as big as Roman cargo ships; the later Chinese clippers were ten times as big and twice as fast.
The first machines: water and windmills
The production of food for a growing population and the manufacture of metals brought manpower and livestock to the limit of their capabilities. Food and metal production, therefore, benefited particularly from the first mechanical energy converters: Water and windmills that were used to grind grain, press oil and work metal.
Water wheels were already around 200 B.C.E. used in China, but were initially not superior to animal-powered mills and pumps. From the 9th century onwards, they were widely used. Windmills were first used in the Middle East around the year 600; in Europe it began to spread in the Middle Ages. The advancement of both types of mills has played an important role in the mechanization of the world. After 1800, with the use of iron components and improved lubrication, their performance and importance increased rapidly; In 1849 the power of the water wheels in the USA was half that of all steam engines. The metal water wheels also led to the construction of the first water turbines, which were used from 1832 to drive forge hammers and from 1880 to generate electricity.
The development of the water wheels was reflected in the Windmills: With technical improvements, millions of windmills in the USA took over primarily to drive water pumps, while in Europe 30,000 larger systems, especially along the North Sea, actually served as mills - and as pumps drained the land. In terms of energy, the age of agriculture was also called "Regime of controlled solar energy flows”(200) denotes: People continued to depend on the flow of solar energy, but could at least partially control the conversion of solar energy into biomass with agriculture; and learned to use water and wind power.
Per capita energy consumption of industrial societies: Everyone uses
70 to 80 times the human basal metabolic rate, especially fossil fuels
(see below). Own illustration.
In pre-industrial times, the use of coal an emergency solution: coal was dirty and was only used when firewood or charcoal became scarce and expensive. But it was to be inextricably linked with a change, the effects of which were as revolutionary as those of the invention of agriculture: the >> Industrial Revolution. Coal deposits are the results of a >> long-term conversion of forests from the >> carbon (hard coal) and the >> cenozoic (lignite). Their use thus also means a transition from renewable energy sources to fossil fuels (the "Fossil energy regime”, ie the replacement of solar energy flows as the most important source of energy through the depletion of energy stocks that have arisen in the course of geological times.
The large coal deposits in Europe had been on a small scale since the 13th and 14th centuries. Century been mined, as far as the mining in open pit or short shafts was possible; Coal was also known in China. But their breakthrough came when wood and charcoal became scarce and the steam engine made it possible to pump out the groundwater known as “pit water”, which ran into the ever deeper pits. In this way, coal made it possible to extract more coal, and so the steam engine was to determine the face of the industrial revolution. At the beginning of the 19th century, coal-powered steam engines became increasingly popular as stationary and soon also mobile (steam ships, locomotives) sources of energy; This made it possible to use coal in industries outside of the discovery areas; cities such as London, Boston, New York and Berlin were illuminated with town gas extracted from coal. Coal consumption rose rapidly: from 10 million tons in 1800 to 76 million tons in 1850 to 760 million tons in 1900; coal now covered 90 percent of the world's fuel needs. (In England as well as Western and Central Europe this was the case earlier, but it was not until the 1890s that coal also became the most important fuel in the USA; here the forests had previously provided enough wood and charcoal - the late settlement by the Europeans had until then Part of the forests was saved from destruction. In other countries in the early days of industrialization, hydropower continued to be important, for example in Switzerland and Japan an energy consumption of 11.4 kWh / day per inhabitant, i.e. more than six times the human basal metabolic rate.
The greatest advantages of coal (and the other fossil fuels such as oil and gas, see below) are their high energy density and that they can be easily transported and stored; thus can be used regardless of location. The use of energy, and even more so the energy services used, have since reached entirely new dimensions and changed our entire lives: the mechanization of agriculture freed people to work in industry (after the Second World War, less than half of humanity worked in agriculture for the first time what British historian Eric Hobsbawm has called the most dramatic social change of the 20th century); the land that was previously needed to grow fodder for the oxen and horses that pulled plows and wagons - a quarter to a third of the arable land in North America and Europe - for the cultivation of human food. Herbicides and pesticides produced using petrochemical processes further increased agricultural yields; Today it feeds over seven billion people (more: >> Industrial agriculture). Heavy physical labor was largely taken over by machines and industrial mass production was made possible; railways, cars and airplanes have fundamentally changed mobility; The forms of communication and information processing made possible by >> electricity are currently changing our lives. Today every person on earth constantly uses an average of 43.2 kWh / day of technically generated energy - about as much as 25 hard-working people can achieve in the long term. But the major regional differences are more important: In India this value is 12 kWh / day, in China 33.6 kWh / day, for an average European 127 kWh / day, for a German 132 kWh / day (>> more) and for an American over 250 kWh / day.
Development of world energy consumption in the industrial age (from 1860 to 2010): The increasing per capita consumption and the increasing world population resulted in an enormous increase in energy consumption, especially after the Second World War. (The unit Mtoe means millions of tons of oil equivalent.) Own figure based on >> Murck, Environmental Science and BP Statistical Review of World Energy June 2011 / International Energy Agency Key Energy Statistics 2010. In this figure, as in most representations, the statistical The recorded use of traditional biomass (wood, dung, etc.) in the Third World is underestimated, it currently amounts to at least 10 percent of the total energy consumption (>> more), so the primary energy consumption is over 13,000 Mtoe (= 545 EJ) (without it according to BP Statistical Review of World Energy June 2011 at 12,002 Mtoe).
As the above figure shows, coal didn't even play the main role: oil was - after Edwin Drake had first successfully drilled for oil in Pennsylvania in 1859 - initially used to extract kerosene as lamp oil and thus to replace the increasingly scarce and expensive whale oil. Soon, however, its advantages over coal - higher energy density, easier transport, cleaner combustion, versatility - became clear. To do this, petroleum must be processed before it can be used; in refineries it is broken down into its constituent parts. First, from around 1910, the transition to oil began in the USA - also because cars were the most common here. The car was initially a toy for the rich; But ever since car owners, car manufacturers, and the oil and tire lobbyists had succeeded in putting enormous amounts of public money into road construction and Henry Ford's assembly line system making the car affordable for the middle class, >> it settled down Automobile as a means of transport. From 1950 the transition also began in Europe and Japan. A worldwide network of production facilities, pipelines, tankers and refineries emerged, and in the early 1960s crude oil became the most important fossil fuel. Today, its share in global energy consumption is around 34 percent, and almost 60 percent of the oil is used in transport (more on this: >> A Brief History of Petroleum).
Also plays since the 1980s natural gas an increasing role. Although the American city of Pittsburgh had already replaced its town gas with natural gas in 1883, when lighting became cheaper with electricity, the natural gas, which often occurs together with oil, was no longer used. For decades, the gas produced in oil production was simply flared; its widespread use only became possible with the development of high pressure pipelines (the other means of transport used today is expensive liquefaction and transport as liquefied gas). Today, with a share of around 24 percent of global energy consumption, natural gas is the third largest energy supplier after oil and coal. It is mainly used for space heating, industrial processes and power generation; By using natural gas as a hydrogen and energy source for the Haber-Bosch process for the >> production of artificial fertilizers, it also contributes to increased yields in agriculture. Today, coal has an increasing share of almost 30 percent of energy consumption worldwide, over three quarters of which goes into industrial energy and electricity generation.
The most versatile energy: electricity
Fossil fuels have also been used since 1882 to produce high-temperature steam, which can be used with generators, just as with water power electricity could generate (>> here). With the conversion into electricity and its transport in lines, the hydropower could now also be used regardless of location; And compared to the steam engine, electricity was an extremely convenient and versatile form of energy use: it comes from the mains (no tanks or storage cellar required), is clean at the point of consumption, and can be used for space heating and transport (electric motors) to lighting at the push of a button solve all the tasks that we expect from energy. Its triumphant advance began at the beginning of the 20th century with the construction of large power plants and high-voltage lines for electricity distribution (Germany had been a pioneer here since 1885); Wherever the expensive infrastructure was first set up - first in the USA, then in Europe - electricity gained enormous importance: In 1950, 10 percent of fossil fuels were used to generate electricity, by the end of the century it was 40 percent. Above all, electricity enabled small applications such as washing machines or radios to be supplied; the modern world with communication and information technologies and automated production processes would be inconceivable without electricity. Completely new industries such as aluminum production were also made possible by electricity. In 2008, 20,181 terawatt hours of electricity were consumed worldwide, that is 20,181 billion kilowatt hours.
The fossil fuels coal, gas and oil generate around two thirds of the world's electricity, the remaining third is generated in roughly equal proportions by hydropower plants and nuclear power plants. Hydropower plants were developed around the same time as power plants that burn fossil fuels; Large power plants have been built since the 1930s (>> more). Nuclear power plants use the energy that is created when atomic nuclei split to generate hot water vapor; Their use is controversial, especially because of the associated handling of radioactive substances (>> more). With ). With a good two percent share of electricity generation, waste incineration and (in addition to hydropower) other renewable energies (Wind energy, solar energy and others) make up a small but rapidly growing share of electricity generation.
In pre-industrial times, energy use mainly meant the conversion of natural ecosystems into areas for agriculture and the deforestation of forests (see >> Environmental changes in the age of agriculture). The intensive use of fossil fuels since the industrial revolution was accompanied by >> tremendous air pollution. In the rich industrial countries this is largely a thing of the past thanks to the replacement of coal as fuel in households and modern filter technologies; but still an acute problem in emerging countries like China and India: the air in Beijing is as bad as it was in the Ruhr area in 1960. A global challenge today is caused by the burning of fossil fuels >> Climate change With the release of greenhouse gases, humans have triggered a change in the earth's energy balance that is far greater than their direct energy consumption: The global primary energy consumption corresponds to an output of over 17 terawattsthat drives our global industrial society. According to the report of the Intergovernmental Panel on Climate Change of >> 2007, the radiative forcing (i.e. the warming caused by the greenhouse gases) through climate change was 1.6 watts per square meter - and this corresponds to an additional power of 850 terawatts! This means that the greenhouse gases have a total energy output that is almost 50 times greater than that which the fuels provide directly. To classify these values, let us compare them with some values from nature: The total solar radiation on earth is >> 174,260 terawatts, the total photosynthesis output on earth is estimated at around >> 250 terawatts. The power with which the >> movement of the earth's plates over the earth's surface is driven from the earth's interior is estimated at 40 terawatts. (However, the value is exceeded by short-term peak values: The tsunami of December 2004 in the Indian Ocean released an output of over 2,000 terawatts.)
(Large) hydropower plants also have negative environmental effects, more on this >> here. Nuclear power plants are controversial because of the dangers posed by the radioactivity they contain (see >> here).
The transition to fossil fuels was essentially a matter of industrial societies: in the first half of the 20th century, Europe and North America consumed 90 percent of fossil fuels. At the beginning of the 21st century, the rich 20 percent of the world's population was still consuming 70 percent of fossil fuels; the US alone, with 5 percent of the world's population, 27 percent - an American consumed on average as much energy as 30 Indians or 100 people in Bangladesh. (The energy consumption of the US military alone exceeds that of two-thirds of all countries in the world, including rich countries like the - admittedly small - Switzerland.)
For the poor majority of the world's population, the situation is still the same as in the rich countries before the industrial revolution: Over three billion people mainly use their own physical strength, pets, wood, charcoal, dung or plant residues. Around two billion people overexploit the resources of their environment; at least 100 million people do not have enough fuel to meet basic needs such as food preparation. Indoor air pollution caused by burning poor quality fuels in fireplaces or poor stoves kills three million people every year (>> more).
The fossil fuels that marked the industrial revolution are finite and, once easily accessible supplies are exhausted, they are becoming increasingly difficult and expensive to mine. A time of cheap energy ends with this (see the example of oil >> here); and on the other hand, the environmental consequences of the use of fossil energies such as climate change make it seem advisable anyway to restrict the use of fossil energies. The “fossil energy regime” is coming to an end; and since atomic energy, once promoted with great expectations (>> here), has disappointed the hope placed in it, we will (again) have to get by with solar energy flows. This “third” solar age, as it will arise with completely different knowledge and skills, will of course look very different from the time before the use of fossil energies; how such a sustainable (>> here) energy supply could look like for the future is shown >> here.
Swell: see >> here.
More about energy on these pages:
>> Energy and its units
>> A little history of exploring energy
>> A little history of petroleum
>> The end of cheap oil
>> A little history of atomic energy
>> Energy transition
Strategies for the future:
>> Clean energy
© Jürgen Paeger 2006 - 2017
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