Peak People: The Interrelationship between Population Growth and Energy Resources

This is just the section regarding the human population effect of energy sources. Population growth has increased along with the industrialization that oil and other natural resources brought, but they are finite. As we crest the peaks of various resources, will we see population decline as well?

Figure 12 shows the sum-of-energies model of population growth versus actual population growth, projected to 2050.

Figure 12: World Population vs. Sum-of-Energies Population 800-2050

What Next? - Future Scenarios

There are three general scenarios that the world’s energy future may take. Their effects on population will be radically different. They are:
1. Continued fossil fuel growth
2. Fossil fuel decline and no sufficient substitute
3. Fossil fuel decline and a new source of energy

Scenario 1: Continued Fossil Fuel Consumption Growth

In this scenario, fossil fuel consumption continues to grow at similar rates to the recent past and population grows as projected by the United Nations to 9 billion people by 2050.
Based on the above sum-of-energies model, if Oil Population is close to reaching its peak, a much larger share of the world’s population growth will have to be driven by Coal Population, requiring much higher consumption of coal. Unless carbon sequestration technologies quickly become viable, this will have detrimental effects on climate change.
The increased importance of natural gas in the 21^st century may also contribute to population growth, as the introduction of new energy sources has done in the past. But based on current trends natural gas will play a much smaller part than coal.
Or population may already be slowing more quickly than most analysts realise.^[14] If so, the world’s population in 2050 may be substantially lower, closer to 7.5 billion people (1 billion for Biomass Population, 2.5 billion for Coal Population, 2.7 for Oil Population and 1.1 for Natural Gas Population equals 7.3 billion).

Scenario 2: Fossil Fuel Decline and no Sufficient Substitute

Figure 13 - Population/Energy Dependency - After Peak Energy Production

A decline in oil and gas production would mean a decline in energy inputs into society, a decline in productivity and, hypothetically, a decline in population. If population growth were related to oil production and oil production is beginning to decline, Oil Population will also decline – in other words, its growth curve may change from a slowing logistic curve, to a declining parabolic curve - and therefore a large component of global population will decline more quickly than most people anticipate.
Mortality rates may increase, as a population grown large through dependence on high quality energy sources now must allocate scarcer resources per person. This is evident in agriculture’s dependence on fossil fuel based fertilisers^[15]. Without them, agricultural productivity decreases and less people can be fed. Human carrying capacity decreases.
Figure 14 depicts projected world oil production to 2020. These figures are based on conventional crude oil resources and natural gas liquids (CO + NGL). They do not include unconventional oil resources such as shale oil, oil from tar sands, ultra-deep water oil or polar oil. These oil sources are not included because they are much more expensive to extract, in monetary terms but also in energy terms. In other words, a large amount of energy inputs are required to extract energy outputs from say, tar sands in north western Canada. Hence the net energy gain is lower, and these energy sources may not be as important in raising productivity and population ceilings.
Based on these projections, the 3.2 billion people that are dependent on oil in the sum-of-energies population model are in serious jeopardy in the next fifty years as the world’s remaining oil resources are consumed, and world population could suffer a precipitous decline.

Figure 14: Projected World Oil Production

Source: Kebab at http://www.theoildrum.com/files/PU200808_Fig3b_0.png

Scenario 3: Fossil Fuel Decline and a New Energy Source

This scenario follows from Ester Boserup’s observations that many of humankind’s technological innovations have resulted from population pressures, or increased population densities. According to Boserup, demand-induced innovation led to the shift from hunter-gatherer societies to agricultural societies and from the use of wood to coal. One could speculate that a shortage of fossil fuels caused by population pressures would lead to yet more innovation and the discovery of newer and better sources of energy. From our vantage point though, it is not clear what these innovations might be or what new sources of energy would be capable of replacing fossil fuels.
A higher quality energy source, say fission, could lead to further productivity improvements, reducing the pressure on existing resources and further raising the ceiling on population size. But fission still lies closer to the realms of science fiction than science.
A lower quality energy source, like solar or wind power, is less efficient. It has less ability to perform work and to raise productivity. Another problem with low quality energy sources is that their net energy is low - they require a large proportion of energy in, to get some energy out - in contradistinction to oil and gas, which have high net energy values. A switch to a lower quality energy source from fossil fuels will put further pressure on other remaining energy sources, such as wood and coal. This could lead to further pressures on land and other resources and hence lower the population ceiling. Low quality energy resources do not support large populations.
Nuclear power is not the answer. To replace diminishing oil and gas (which currently provides the world with 60% of its energy resources) with nuclear power (which currently provides 5.6%) would not only require vast amounts of capital but would require vast amounts of high quality energy. In a period of declining oil and gas resources, existing energy sources would be getting scarcer.
Perhaps a new high quality source of energy will be found. This would then add a new energy component to population growth. This may lead to a raised population ceiling and an initial burst of population growth as population grows to occupy the space between the previous ceiling and the new ceiling. Then growth may slow again as a new equilibrium is reached.

Peak People: The Interrelationship between Population Growth and Energy Resources | Energy Bulletin