Why a chapter on population and energy?

Because in a very real sense it is the measure of how many live on this planet and how much energy is used for our own purposes that brings into stark consideration the fundamental, inviolate rule: that we cannot sustain an existence that isn’t in balance with what our planet can provide for us. ‘Us’ of course meaning every living thing on the planet.

The story of our energy use is scary to the extreme. By using the term ‘our energy use’ I am offering it as a label, so to speak, for the number of people multiplied by the energy each person is using.

So, first let us start with global population.

The world did not reach a population of one billion until 1800. One hundred and twenty-three years later, in 1927, that global population figure passed two billion persons. That, in itself, isn’t remarkable. But what was remarkable was the continuing growth.

Thirty-three years later, in 1960, the global population reached three billion.
Twenty-four years later, in 1974, the population reached four billion.
Thirteen years later, in 1987, the world population is up to five billion.
Twelve years on, in 1999, up to six billion persons in the world.
Then just another thirteen years on for the population to reach, in 2012, seven billion.

Now that is not a cast-iron guarantee that the growth will continue on and on in a similar fashion. Recall that old saying, “I can predict anything except those matters involving the future!”

Indeed, the UN’s Economic & Social Affairs Department, in a report issued in 2013, under the title of World Population Prospects – 2012 Revision, offered in Figure 1. Population of the world, 1950-2100 (Page XV of the summary.), four possible outcomes, “according to different projections and variants.” Those being Medium; High; Low and Constant-fertility. Just to pick the extremes projected, a Constant-fertility growth would bring the global population in 2100 to twenty-eight billion persons, and a Low growth future delivering more or less today’s global population of seven billion persons.

What is the maximum carrying capacity of the planet? A number of estimates of the carrying capacity have been made with a wide range of population numbers. A 2001 UN report said that two-thirds of the estimates fall in the range of 4 billion to 16 billion (with unspecified standard errors), with a median of about 10 billion. More recent estimates are much lower, particularly if resource depletion and increased consumption are considered.

Now if seven billion people might be (and I do stress ‘might be’) more than Planet Earth can sustain today, then don’t even start to go to future population levels of the order of sixteen billion (High) or twenty-eight billion (Constant-fertility)!

However, this is a chapter on population and energy, not just population per se. Population growth is only one part of a complex energy nightmare. A huge nightmare. We must look at the other factor: our energy use. It is both a cause and a consequence of the population numbers.

The energy used by each person, measured in kilowatts on an annual basis, remained pretty constant right up to the middle of the Industrial revolution. For example, in 1800, the energy use per person was less than two kilowatts (A kilowatt is a thousand watts) of power a year. Today, that low figure from 1800 is almost beyond imagination in terms of the energy used today!

The Industrial revolution changed everything; irrevocably. By the end of that century, 1900, while the energy use per person was slightly up, the global population was steadily increasing; as explained a few paragraphs back. Thus the total energy being used in 1900 was the sum of energy used per person times the number of persons worldwide.

As it logically is the same total calculation used coming forward to the year 2000; where the energy use per person is up to three or four kilowatts a year (the chart being used was difficult to read precisely) and the population is now around seven billion! Seven billion people using three to four kilowatts of power produces a global use of energy of fifteen terawatts (The terawatt is equal to one trillion watts!) That’s fifteen trillion watts of energy!

Once more, looking into the future is challenging; to say the least. The awareness and uptake of solar electricity panels is expanding; the idea of cars being powered by other means than petroleum fuels is becoming a reality but the broader picture of total energy used across the world reveals an intense dependency of energy for some time. Indeed, we can use the UN’s forecast of population growth out to 2050 to construct a prediction of future energy needs, again on an energy per person energy equivalent.

This shows total global energy use peaking about now (2015), to the tune of 80 gigajoules per year (The equivalent of 22 megawatt-hours per year), of which 80 percent is from the use of fossil fuels, then slowly declining by 2050 to 30 gigajoules per year, of which nearly 70 percent would be from the use of non-fossil fuels.

Indeed, you may have heard about recent declines in energy consumption in both Europe and the US, but these declines have been more than offset by increases in energy consumption in China, India, and the rest of the “developing” world.

To put this into some form of historical perspective, using the assumptions chosen, the world per capita energy consumption in 2050 would be about equal to what the world per capita energy consumption was back in 1905.

Assuming we haven’t trashed the planet before then!

930 words. Copyright © 2014 Paul Handover