Question

Using a simple numerical model with global supply of energy resources denoted as R; world population as N; per capita energy consumption as E, S as the standard of living and efficiency of transforming energy into wealth denoted by f, show that it is vital to have a growth in the efficient use and generation of energy in order to increase the standard of living (S) and decrease the energy resource use (R).

Answer 1

Energy Production & Changing Energy Sources
Access to energy is a key pillar for human wellbeing, economic development and poverty alleviation. Ensuring everyone has sufficient access is an ongoing and pressing challenge for global development.

However, our energy systems also have important environmental impacts. Historical and current energy systems are dominated by fossil fuels (coal, oil and gas) which produce carbon dioxide (CO2) and other greenhouse gases- the fundamental driver of global climate change. If we are to meet our global climate targets and avoid dangerous climate change, the world needs a significant and concerted transition in its energy sources.

Balancing the challenge between development and environment therefore provides us with an ultimate goal of ensuring everyone has access to enough sustainable energy to maintain a high standard of living.

In this entry we attempt to cover the fundamental pillars we need to understand global and regional energy systems: their evolution through time in terms of consumption, relative sources, and trade; progress in global energy access and our transition towards low-carbon sources; and crucially the main development, economic and health drivers behind the energy choices we make. It is intended to provide a fundamental background to the macro-trends in our historical and current energy systems, with key learnings on how we can use this understanding to shape pathways towards a sustainable future.

Global total energy production – long-run view by source
Let's first take a look at how global energy production- both in terms of quantity and source- have changed over the long-term. In the visualisation below, we have plotted global energy consumption from 1800 through to 2015. Note that you can use the absolute/relative toggle on the chart to view these in absolute numbers or as the percentage of the global total.

If we start back in 1800 we see that nearly all of the world's energy was produced from traditional biomass (essentially burning wood and other organic matter). The world (predominantly the UK) was using a small amount of coal- only around two percent. Our expansion into oil consumption didn't begin until around 1870. Two decades later it was followed by natural gas and hydroelectricity. By 1900, coal consumption had increased significantly, accounting for almost half of global energy (the other half remaining biomass, since oil, gas and hydroelectricity remained small).

By the mid-20th century, the energy mix had diversified significantly; coal overtook traditional biofuels and oil was up to around 20 percent. By 1960 the world had moved into nuclear electricity production. Finally, today's renewables (modern biofuels, wind, and solar) are relatively new, not appearing until the 1980-90s. Other renewable sources, such as geothermal and marine technologies, have not been included because levels of production are so small.

In 2015, the world consumed 146,000 terawatt-hours (TWh) of primary energy- more than 25 times more than in 1800. But it is often today's energy mix, rather than levels of consumption that people find surprising. While some may have the impression that renewables account for a large share of global energy consumption, their total contribution in fact remains small.1 Even if we include modern biofuels and hydropower, it is still less than five percent. We have a long way to go if we are to transition from a fossil fuel dominated energy mix to a low-carbon one. Investment and the production of renewable technology is growing, however, as we show in this entry.

Energy production through time, by region
How are total levels of consumption distributed across the world's regions? In the chart below we see primary energy consumption from 1965-2015 aggregated by continental regions. Note that this dataset only includes commercially-traded fuels (coal, oil and gas), nuclear, and modern renewables. This means traditional biofuels are not included; as a result, figures are likely to be a small underestimate for regions (predominantly Africa and developing Asia) where populations still strongly rely on traditional biomass as a primary fuel source.

In 1965 the bulk of total energy was consumed North America, Europe and Eurasia- collectively, they accounted for more than 80 percent of global energy consumption. Although energy consumption has increased in these regions since the 1960s, their relative share of the total has declined significantly. Consumption across the rest of the world has been increasing, most dramatically in the Asia Pacific where the total consumption increased more than 12-fold over this period.

As a result, in 2015 Asia Pacific was by far the largest regional consumer with 42 percent- this was about the same as North America, Europe and Eurasia combined (at 43 percent). The Middle East, Latin America and Africa account for around seven, five and three percent, respectively.

As well as comparing the total quantity of primary energy consumed, we can also breakdown the contribution of different sources across the regions. In the chart below we can see how North America's energy mix has evolved through time. You can use the 'change region' function on this to see the contributions in other regions.

What is perhaps more surprising than the relative difference in the energy mix between regions is how regional mixes have changed (or rather, haven't changed much) through time. This is more clear when using the 'relative' toggle on the chart, which presents each source's contribution as the percentage of the total. If we look at the relative contribution of different energy sources in North America, Europe and the Asia Pacific, for example, the rate at which the energy mix has changed with time is fairly slow. With the exception of the onset of nuclear electricity, the energy mix has, for the most part, been fairly constant for at least half a century.

This is a key point from Vaclav Smil's book on energy transitions; shifts in energy systems have historically been a slow process, particularly when coupled to long-term infrastructure.2 This may explain the slow and marginal progress we have made in the transition to modern renewables, and is a challenge we must acknowledge if we are to achieve a large-scale shift in our global energy systems.

Long-run view for single countries

While most people associate the advent of energy with the uptake of coal, it's important to understand what modern fuels have replaced by taking a long-term perspective on the evolution of human energy systems. In the chart below we see long-term trends in energy transitions in Italy; this figure has been developed based on data from Gales et al. (2007).3 Similar data across a range of countries in Europe and the Americas has been made available at the Energy History project at the Joint Center for History and Economics, Harvard University and University of Cambridge you can explore these trends using the "change country" function in the chart below.

These trends provide an additional energy dimension: human and animal power. The inclusion of muscle, food for labour and animal feed reminds us of the important earlier transition in these economies from human and animal labour to industrialised energy production. In high-income countries, the uptake of fossil fuels- and later, the integration of renewable and nuclear technologies- has effectively eliminated the use of human or animal labour. In some low-to-middle income nations, the contribution of a human labour force (especially in agricultural and manufacturing sectors) is still significant, but continuing to progress through the composition shifts we see in the figures below

4 Access to electricity
Share with access to electricity
Electricity is a crucial for poverty alleviation, economic growth and improved living standards (these links are discussed later in the entry).4

Measuring the share of people with electricity access is therefore an important social and economic indicator. There is no universally-adopted definition of what 'access to electricity' means. However, most definitions are aligned to the delivery of electricity, safe cooking facilities and a required minimum level of consumption. The International Energy Agency (IEA) definition entails more than just the delivery to the household. It also requires households to meet a specified minimum level of electricity, which is set based on whether the household is rural or urban, and which increases with time. For rural households, this minimum threshold is 250 kilowatt-hours (kWh) per year and for an urban household it is 500 kWh per year.5

At a global level, the percentage of people with access to electricity has been steadily increasing over the last few decades. In 1990, about 73 percent of the world's population had access; this has increased to 85 percent in 2014.

High-income countries have typically maintained close-to-maximum (95-100 percent) access since 1990. The increasing global share has therefore been driven by increased access in low and middle-income economies. In many countries, this trend has been striking: access in India, for example, increased from 45 percent to almost 80 percent. Indonesia is close to total electrification (sitting at 97 percent) – up from 60 percent in 1990. For countries with strong population growth, such improvements in the share of the population with access is even more impressive.

Whilst the trend is upward for most countries, a number are still severely lagging. At the lowest end of the spectrum, only 8 percent of Chad's population has electricity access. For some countries, significant improvements in access will remain a pressing challenge over the next few decades.

The total number of people with access to electricity

Despite population growth, the absolute number of those without electricity access has also been declining as shown in the chart below: the number without access has decreased from 1.4 billion in 1990 to just over a billion (1.07) in 2014.

During this 24 year period, the number of people with access to electricity increased by 2.3 billion. This means that on average the number of people with access to electricity increased by 262,600 every single day in these 24 years