POPULATION GROWTH AND
ENERGY
Filip Černoch
cernoch@mail.muni.cz
ESS 411 – Environmental
aspects of energy
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Source: Česká
televize
The math of population growth
 Exponential growth - growth that increases at a consistent rate.
 xt=x0(1+r)t
 The rule of 70 – to find the doubling time divide the percentage
number into 70 = approximate number of years needed to
double.
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Carrying capacity
 A population doesn´t usually grow indefinitely → limiting factors
 Density dependent factors
 Density independent factors.
 They create the carrying capacity limity of given habitat
 = Population is limited to the carrying capacity of its habitat.
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Population growth
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Zdroj: BBC
Development of the society – maximalisation of energy flows
 „In every instance considered,
natural selection will so operate as
to increase the total mass of the
organic system, to increase the rate
of circulation of matter through
the system, and to increase the
total energy flux through the
system so long as there is present
and unutilized residue of matter
and available energy (Alfred
Lotka, 1922).
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Development of energy consumption
The first energy era (ended with the first settled societies some 10 000 years ago).
 Human metabolism + fire
 Muscles to secure food, shelter, aquiring material
 Useful work of healthy adult – 50 – 90W
 Energy returns in foraging – barely positive to as much as 40x .
 Densities less than 1 person/km2, agriculture societies 20-30 people/km2.
 First usage of draft animals to cultivate the fields.
 Sustainable (= able to be maintained at a certain level) economy =damages
were reparable.
= If the ecosystem was harmed too much and stopped providing the resources
people moved to another place.
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Development of energy consumption
The first energy transition (preindustrial societies)
 Domestication of draft animals + fire to produce metals = increase of energy
usage
 Animals – 200 – 500W
 Fire to produce bricks and containers and to smelt metals
 Charcoaling to convert wood to charcoal to iron (inefficient process)
 Nearly complete deforestation of some parts of Mediterranean (Spain, Cyprus,
Syria – iron) and the Near East (Iran, Afghanistan – copper).
= considerable impact of people on the environment. Development is prevented
by the limits of the environment.
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Development of energy consumption
First prime movers
 Muscles replaced by waterwheels and windmills to grain milling, oil pressing,
wood sawing etc.
 Late 11th century England – more than 5600 water mills, 1/350 people.
 Higher performance of draft animals (better harnessing, shoeing etc.)
 Production of metals limited by the limits of environment:
 Early 18th century – typical English furnace produced app. 300 tons of pig
iron/year. 8kg of charcoal per 1kg of iron, 5kg of wood per 1kg of charcoal =
annual demand 12 000 tons of wood. All natural forests gone.
 1 mill tons of iron requires ¼ of the British Isles under coppiced wood.
= in 1200 London surrounding is deforested, by 1500 metal ores shipped to
Ireland, Scotland, Wales for smelting, then it moves to U.S.
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Development of energy consumption
Industrial age
 Substitution of animate energy by engines and energies of fossil fuels (still in
process – Africa)
 By 1900 several European countries energized by coal
 Previously the lack of energy prevents the population from (also economic)
expansion. No spare resources for education, science, technological
development. It was changed by the fossil fuels.
 Watt´s steam machines 20kW. Industrialization, transportation, rise of well
being. An inexpensive and reliable supply of heat and electricity.
 But environmental consequences (serious changes of interactions in the
ecosystem)
 = fossil fuels provided a critical amount of energy for the humankind to
develop. They (for uncertain period of time) removes the limits of (economic
and population) expansion.
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Development of energy consumption
Latest energy transition (since the world´s first enectricity plant in 1880s)
 Electricifaciton and inovation
 An inexpensive and relable supply of electricity transformed every
aspect of everyday activities – light, time-saving gadgets, energizing
transport, boosting industrial production.
 By 1950 oil and gas approx. 35 % of the world´s primary energy supply
and by 2000 their combined share over 60 %. With coal fossil fuels
provides 90 % of all commercial primary energy supply.
 = fossil fuels drive up farm productivity and hence reducing (drasticlly)
agricultural population by mechanizing industrial production and letting
the labor force move into the service sector.
 But their impact on the environment is tremendous.
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Population growth
 Driven by fecundity – how many offspring individual may have in
his lifetime.
 Limits of population growth – conditions for life and
reproduction.
 Food, temperature, space...
 Carrying capacity – number of inhabitants that ecosystem can
sustain with available sources.
 Limits of growth supressed by „infinite“ amount of energy from
fossil fuels. – mechanisation of agriculture + medical advances +
savage systems + living in formerly unhabitable places.
= combination of the expansion of consumption of fossil fuels + population
growth = pressure on the environment = impact on humankind.
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Development in energy consumption
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Approaches
 Cornucopians (boomsters, vs. Malthus and followers =
doomsters)
 Reformists: Work within existing structures to make
society more “green”
 Revolutionaries: Sustainability is not possible without
radical change
 Environmental determinists: Ecological limits will impose
changes on society whether we like it or not
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Demographic transition model
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Zdroj: W. Thompson
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