On Energy, part 1: How much do we use?

By Levien van Zon
Reading time: 5-10 minutes

We live in interesting times. Humanity has never had as much energy at its disposal as we have had over the last half century or so. Given this abundance, our complex societies have flourished, yet they have also become increasingly dependent on the availability of cheap energy sources. The last few decades however, things seem to be changing. Fossil energy is becoming increasingly expensive², and the negative side-effects of burning large amounts of fossil fuels are becoming apparent.

The past years have been the warmest years on record¹, and the first effects of global warming on regional climates are starting to become apparent and are already causing problems for people all over the world. In an international effort to slow climate change, many countries signed the Paris climate treaty in 2016. Under the treaty, countries committed themselves to basically phasing out atmospheric emissions from fossil fuels by 2050.

While most industrialised countries are still very much dependent on fossil fuels, an increasing number of countries and companies are starting to see the transition away from fossil fuels as an economic opportunity. Especially China, although currently the largest greenhouse gas emitter, is positioning itself as the leading provider of alternative energy infrastructure.³ Technological development and increasing investment in alternative energy have led to a sharp drop in the prices of wind and solar power. Meanwhile, anticipating the shift away from oil, most major car brands have announced plans to move away from combustion engines and focus exclusively on electric vehicles in the near future.

Yet, we’re only at the start of a transition away from fossil energy, and serious challenges remain on our way. The United States, globally the second-biggest emitter of greenhouse gasses, currently has a national government bent on stretching and even increasing fossil fuel use for as long as possible. Perhaps more seriously, few people realise how much fossil energy we actually use. While scaling up alternative energy sources to this level is theoretically possible, it is certainly not going to be easy, especially not in the short term and not in all countries.

This is the first of two articles on energy use.⁴ In this article, I shall look at how much energy we use and where it comes from.

A brief history of energy

As I already suggested in the introduction, we live in a rather unique period in history. Not only do we have more energy at our disposal than ever before, energy has also never been as cheap as it has been over the last century or so. Granted, especially oil prices have fluctuated quite a bit during this period, as you can see in the chart below. As recently as 2011, the price of crude oil was at an almost historic high. At $0.74 per litre, the oil price in 2011 was more than ten times that in 1970! But we easily forget that oil actually contains a lot of energy. A convenient measure of energy is the kilowatt-hour (kWh), which I will explain in a bit, but which you may recognise from your electricity bills. A litre of oil contains roughly 10 kWh of energy, so even the extremely high 2011 oil price translates to a mere 7 dollar-cents per kWh, which, in the grand scheme of things, is really not that much.⁵

The global price of a litre of crude oil from 1860 to 2015. Historical prices are inflation-corrected and are expressed in 2015 US dollars, for fair comparison. Click on the image for more information. Data source: BP Statistical Review of World Energy, June 2016

Fact is that we all have become rather dependent on energy being so cheap, because we use an incredible amount of it, especially in industrialised countries. In many ways, this abundance of cheap energy is a good thing. Energy quite literally powers everything we do. Things like food production, transport, heating and cooling become a lot easier and cheaper with abundant energy, and modern communication wouldn’t even be possible without it. So what exactly is the problem?

Take a look at the following graph, which shows how much energy we humans use per day, and where it comes from, from 1800 until the present day. (These are fairly rough estimates, expressed in terawatt-hours, a unit which I shall explain in a moment.)

Until the nineteenth century, people almost exclusively used biomass (stuff directly derived from plants or animals) as an energy source. Things like cooking, heating and lighting were done using wood, charcoal, peat, dung and whale-oil. Transport and agriculture were mostly powered by humans and animals such as horses, mules and cattle. Wind and water played an important role as well, in industry (windmills and watermills) and in long-distance transport (think sailing ships).

By 1850 the Industrial Revolution was well on its way. The Industrial Revolution was as much about technical innovation as it was about social change and energy transition: Technological developments were intimately tied to the availability of cheap labour and the large-scale mining of fossil coal. But the use of coal was still mostly limited to cities, to industry and to steam locomotives and ships. In 1850, firewood was still and by far the most important energy source for humanity.

By 1900, the use of coal had caught up to be more or less equal to the use of biomass. The half-century that followed saw a further increase in the use of coal for industry, heating and transport. It also saw the slow expansion of car use and the development of aeroplanes, both of which required oil as an energy source. The two world wars were an important driver for technological development and the expansion of fossil fuel mining.

By the end of World War II, the energy provided by coal had doubled again, it now provided almost twice as much energy as biomass. Also, the large-scale use of natural gas and oil really started take off. A mere two decades later, by the 1970s, oil had become the most important energy source, closely followed by coal and gas. This just goes to show how quickly the energy landscape can change.

Since 1800, human energy use has increased roughly 28-fold, and 82% of our energy is now provided by fossil fuels. Of course this enormous increase in global energy use is in part due to the more than seven-fold increase in world population over the last two centuries. If we factor this out and look at the daily energy use per human, the increase since 1800 has been somewhat more modest:

What you can see here is that the energy consumption per person has gone up too: it almost doubled between 1800 and 1950, and has doubled again since then. However, we can see that most of this second doubling actually occurred during the 1960s and 70s. This period saw the rise of energy-intensive consumer culture, personal car ownership and comfortable housing for small families, at least in the Western world. In the 1980s and 90s, recession and increases in energy efficiency temporarily halted the growth of personal energy consumption. Energy efficiency is still increasing today, but unfortunately so is our absolute energy consumption in this age of digital gadgets, data centres, cheap air travel and increasingly heavy cars. This has led to a renewed increase in personal energy use over the last 15 years.

The kWh and other animals

Two centuries ago, in 1800, an average human was estimated to use just over 16 kWh per day. A century ago this had increased to just over 24 kWh per day. Today, the average person uses around 60 kWh per day. Before we continue, what is this kWh-thing exactly? The kiloWatt-hour (kW·h or kWh) is a measure of energy. But how much energy exactly? Let’s look at a few examples (click on the image for more details).

In short, a kilowatt-hour (kWh) is sufficient energy to boil a bucket of water, to drive a bit over 1 kilometre by car, to power a laptop for a few days or to power a smartphone for a few months. As for the terawatt-hour (TWh) I mentioned earlier, 1 TWh is 1 billion kWh. So we humans currently use over 430 billion kWh of energy per day. That’s a very large number, and a very large amount of energy. Then again, there are over 7 billion of us on this planet, so we are a lot of people. This is why I will mostly talk about average energy use per person, in kWh.

I mentioned this figure of 60 kWh per person per day, but actually that’s a bit misleading. This is the average energy use of a human being, but very few people are average human beings. In fact, most humans worldwide use less energy than average. But if you’re reading this, chances are that you’re not one of them, and that you in fact use quite a bit more energy than average. This is what I shall discuss in the next article.

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