Fossil Fuels

Fossil fuels (coal, oil, gas) have, and continue to, play a dominant role in global energy systems. Fossil energy was a fundamental driver of the Industrial Revolution, and the technological, social, economic and development progress which has followed. Energy has played a strongly positive role in global change.

However, fossil fuels also have negative impacts, being the dominant source of local air pollution and emitter of carbon dioxide (CO2) and other greenhouse gases. The world must therefore balance the role of energy in social and economic development with the need to decarbonise, reduce our reliance on fossil fuels, and transition towards lower-carbon energy sources.

This entry presents the long-run and recent perspectives on coal, oil and gas – global and national production, consumption, reserves, prices and their consequences.

Global fossil fuel consumption

Global fossil fuel consumption over the long-term

Fossil fuel production and consumption began with coal – its first reported uses date as far back as 4000BC in China where carving took place out of black lignite (one of the several forms of coal).1. However, large-scale combustion of coal is typically correlated with the period around the beginning of the Industrial Revolution.

The visualisation shows the global consumption of fossil fuels – coal, oil and gas – from 1800 onwards. Overall, we see that global consumption of fossil energy has increased more than 1300-fold. As shown, coal was the first and only fossil source until the 1860s when crude oil consumption began. Natural gas production began a couple of decades later, in the 1880-90s.

The 20th century saw a large diversification of fossil energy consumption, with coal declining from 96 percent of total production in 1900 to less than 30 percent in 2000. Today, crude oil is the largest energy source, accounting for around 39 percent of fossil energy, followed by coal and natural gas at 33 and 28 percent, respectively.

Fossil fuel production

Fossil fuel production by country or region

Per capita fossil fuel production

Fossil fuel consumption

Fossil fuel consumption

The visualisation presents the fossil fuel consumption mix across individual countries and regions over the last 50 years. Data for different countries and regions can be viewed using the “change country” fuinterchangenction of the chart.

Overall, we see large differences across the world, both in terms of the magnitude of fossil energy consumption and their relative mix. Total consumption levels of fossil fuels in higher-income countries have typically peaked, and are now declining as they transition towards lower-carbon energy sources. For example, the United Kingdom’s total fossil fuel consumption is at its lowest level in the last 50 years. In many lower-income countries, total consumption of fossil fuels continues to increase as a result of both population growth and rising incomes (resulting in higher per capita energy demands).

The relative mix of coal, oil and gas in total consumption also varies by country. China, for example, sources more than 70 percent of fossil fuel consumption from coal. In contrast, Argentina sources less than two percent from coal, with gas accounting for nearly 60 percent.

Per capita fossil fuel consumption

Coal

The series of charts present levels of coal production and consumption (which do not necessarily correlate) across the world, by region and country.

Coal production by region

The visualisation shows recent trends in coal production by region, since 1981. Overall, we see that global coal production more than doubled over this period. Although too early to confirm, global coal production appears to have peaked over the years 2013-14, with several years of declining production since. This would represent a significant peak in global energy, with coal being the first fossil fuel energy source.

The majority of growth in global coal production has been sourced from the Asia Pacific region, with 5 to 6-fold growth over the last 30 years. Total output from Europe, Eurasia and North America has declined during this period. Asia Pacific now produces more than 70 percent of coal, up from around one-quarter in 1981.

Coal production by country

The chart and map [which can viewed by switching between tabs] shows the change in coal production at the country level over the longer-term. Most countries have series data back to the year 1900, with some such as the United Kingdom dating back to 1700.

The United Kingdom was the first large-scale coal producer – we see its long-run trend growing, peaking just prior to the First World War, and its gradual decline throughout the 20th century. Its production levels are now comparable to those at the beginning of the 1700s.

Today, China dominates global coal production, accounting for nearly half of total output. This growth has been rapid since the 1960-70s. However, Chinese coal production appears to have peaked, with continued decline in the years since. This decline is likely to have been a key contributor to the apparent global peak in 2013.

Per capita coal production

Coal consumption by region

The chart shows the regional trends in coal consumption over the last fifty years. The relative regional distribution follows a very similar pattern to that of coal production. Asia Pacific is the dominant coal consumer, accounting for nearly three-quarters of global consumption. This share is slightly larger than its share of coal production, suggesting it is a net importer. In contrast, Africa accounts for only 2.5 percent of consumption; less than its 4 percent of production, suggesting it is a net exporter. Collectively, Europe, Eurasia & North America account for less than one-quarter of coal consumption.

Coal consumption by country

Here we see these trends in coal consumption at the national level over the last 50 years. Again, China is the world’s dominant coal consumer, accounting for nearly half of global consumption. Like its production trends, China’s coal consumption appears to have peaked in 2013 with several years of sustained decline.

Other industrialising nations shown strong growth in coal consumption. Driven by continued population growth and economic development, India’s coal consumption grew more than four-fold from 1960 to 1990, and has more than doubled from 1990 to today. Similar trends are seen across various countries, including Brazil, South Africa, Thailand, and Pakistan to name a few.

Coal consumption per capita

Oil

The series of charts present levels of oil production and consumption (which do not necessarily correlate) across the world, by region and country.

Oil production by region

As the visualisation shows, global oil production is much more equally distributed across the world’s regions. Unlike coal production (for which it produces a negligible amount), the Middle East is the world’s largest oil producer, accounting for nearly 35 percent. The relative contribution of region’s to the global total has remained generally consistent over the last 50 years, with Europe & Eurasia and North America both accounting for around 20 percent of total production, and Asia Pacific, Africa and Latin America & the Caribbean all producing between 8-9 percent.

Global oil production has increased more than 2.5-fold over the last 50 years, despite more volatile growth relative to coal. The 1970s ‘oil crisis’ resulted in a sudden drop in consumption between 1973-74 following an oil embargo of the Organization of Petroleum Exporting Countries (OPEC) in 1973. This was followed by another oil shock in 1979 (following the Iranian Revolution) and an ‘oil glut’ in the early 1980s where there was a surplus of crude oil (as a result of reduced consumer demand following the energy crisis of the 1970s).2

Oil production by country

The visualisation shows the change in oil production at the country-level from 1900 onwards, where data is available. This can be explored as a time-series or in map form. In 2014, the United States is the world’s largest country producer of oil, accounting for just under one-fifth of global production. Saudi Arabia is the world’s second largest producer, followed by Russia.

Types of oil production have influenced the shapes of these trends over time. As explored later in this entry, oil production in the United States looked likely to peak and decline in the 1980s before rising again with the extraction of increasing numbers of shale oil resources.

Oil consumption by region

The chart shows oil consumption by region over the last 50 years. Over this period, on relative terms we see a decreasing share of global consumption from Europe, Eurasia & North America in contrast to a rising share in all other regions – most notably Asia Pacific (which has more than tripled in its share of global oil consumption, from around 10 percent in 1965 to 32 percent in 2016).

In comparison to oil production by region, we see that the Middle East is a much smaller consumer than producer of oil (it produces more than 30 percent, and consumes around 10 percent), meaning it is a large net exporter. In contrast, the Asia Pacific region consumes significantly more oil than it produces (only 8-9 percent production versus 32 percent consumption), meaning it is a net importer.

Oil consumption by country

Oil consumption broken down by country is shown in the chart b– in chart, and map form. The single largest oil consumer is the United States, with over 10,000 TWh per year. The USA is followed by China (at 7000-8000 TWh), and India at just under 2500 TWh. Brazil, Canada and Saudi Arabia are also large oil consumers.

Data availability for consumption levels across Sub-Saharan Africa is low. However, given total regional consumption levels are relatively low, we would also expect consumption levels in most countries to be low relative to other regions.

Oil consumption per capita

Natural gas

The series of charts present levels of natural gas production and consumption (which do not necessarily correlate) across the world, by region and country.

Gas production by region

The regional distribution of natural gas production has changed significantly in recent decades. The chart shows natural gas production by region from 1970 onwards. In 1970, North America, Europe & Eurasia accounted for almost all global gas production (with more than 95 percent combined). Despite both regions growing in absolute terms, their share of global production has declined significantly as regional production has diversified. North America, Europe & Eurasia’s share of production has decreased to around 55 percent, with the Middle East, Asia Pacific, Latin America and Africa accounting for 18, 16, 6 and 5, percent respectively.

Overall, natural gas production has nearly quadrupled over the last 40-50 years.

Gas production by country

The visualisation breaks gas production down further to the national level, with some trends extending back to 1900. The United States is the world’s largest single producer of natural gas producer, accounting for approximately one-fifth of global production. The USA is followed by Russia, Iran, Canada, China and Saudi Arabia which all produce more than 1000 TWh per year.

Gas consumption by region

Regional gas consumption shows a very similar distribution to gas production. In the chart we see the dominance of North America, Europe & Eurasia in the 1960-70s, and the significant regional diversification as consumption increases across the world. Relative to gas production figures, we see that the Middle East consumes a smaller share of the global total than it produces, whilst the Asia Pacific region consumes slightly more than it produces. The Middle East is therefore a net gas exporter, whilst the Asia Pacific is a net importer.

Gas consumption by country

Global distribution of gas consumption at the national level also shows a very similar pattern to that of gas production. Like gas production, the United States is the world’s largest consumer, followed by Russia, Iran, Canada, China and Saudi Arabia.

Natural gas consumption has seen significant growth across all regions over the last few decades. This is true of both high and lower-income nations as nations seek to improve domestic energy security, and economies attempt to shift from coal consumption. Natural gas – as we explain later in this entry – produces less carbon dioxide per unit energy than both coal and oil, meaning some countries have adopted natural gas substitution as a pathway to decarbonisation.

Gas consumption per capita

Fossil fuels in electricity

Fossil fuels are consumed for energy supply in a number of ways, including transport, heat and electricity production. In the chart we see the relative share of coal, natural gas and oil in electricity mixes across the world over the last few decades. At the global level we see that coal is the dominant electricity source accounting for approximately 40 percent of total electricity production. This is followed by natural gas at approximately 22 percent, oil at only 4 percent (and the remainder supplied by other energy sources, including nuclear and renewable technologies).

Overall, we see that the share of fossil fuels in global electricity production has not changed significantly over the decade from 2005-2015. If measured relative to the years pre-2000, the share of fossil fuels in the global electricity mix has in fact increased slightly, despite the need for energy decarbonisation. As we cover in a separate blog post, some of this stagnation in progress can be explained by the offsetting of an increase in renewable electricity with a decline in nuclear production.

Fossil fuel reserves

Whilst the terms ‘reserve’ and ‘resource’ are often used interchangeably, there is an important distinction between them. See Data Quality & Definitions for a visual explanation of the difference between the two.

Coal reserves

How are our fossil fuel reserves distributed across the world? We can see the distribution of coal in the chart. The largest coal reserves extend across North America, Asia and Oceania. The United States has the largest coal reserves, at nearly 240 billion tonnes. Russia, China, Australia, India and South Africa are also rich in coal reserves.

Coal reserves by type/quality

Coal sources are not homogeneous – they vary significantly in chemical composition and quality. Coal sources are typically differentiated based on carbon content; coal richer in carbon tends to produce more energy per unit mass (i.e. it has a higher energy yield). The quality of coal also has implications for air pollution. Fuels richer in carbon tend to have lower concentrations of impurities such as sulphur, meaning they produce lower levels of local air pollutants such as sulphur dioxide (SO2). nitrogen oxides (NOx), and ozone (O3).

‘Anthracite’ coal is typically regarded as the highest quality, followed by bituminous, sub-bituminous and then lignite in decreasing order of quality. In the chart we see coal reserves categorised based on type and quality. Globally we see that approximately 70 percent of coal reserves are of higher quality (anthracite & bituminous coal), with the remaining 30 percent of sub-bituminous or lignite grade.

The relative share of coal quality grades vary across the world – national and regional ratios can be explored using the “change country” option. For example, almost all coal reserves in the United Kingdom are of high-quality (anthracite & bituminous), whereas Australia has more lower-grade reserves (sub-bituminous and lignite) than high-grade.

Oil reserves

The picture of global oil reserves is typically more well-known than for coal. Unsurprisingly, the Middle East is the richest region in terms of oil reserves, although on a country basis Venezuela has the largest global reserves at more than 300 billion barrels. Russia, Canada, the United States, and China also have relatively high stocks. Relative to its coal reserves (which are very small), Africa has several countries with relatively high oil reserves: these are predominantly concentrated in Libya, Algeria, Nigeria and Angola.

Gas reserves

The Middle East is also rich in natural gas. Iran has the largest gas reserves at 34 trillion cubic metres, followed by Russia and Turkmenistan. with 32 and 17.5 trillion cubic metres, respectively. Again, the United States, Venezuela, and Saudi Arabia also have relatively high reserves. Overall, the maps for oil and natural gas tell a similar story; the distribution of coal, however, is notably different.

Have we reached peak oil?

Fossil fuels (coal, oil and gas) are finite-consume them for long enough and global resources will eventually run out. Concerns surrounding this risk have persisted for decades. Arguably the most well-known example of this was Hubbert’s Peak Theory-also known as the Hubbert curve (shown in the chart).3

Many have attempted to apply Hubbert’s theory at not only a regional, but also a global level. Most attempts have, however, been proven wrong. We have provided discussion on predictions of peak oil – and why they are often proven false – in our blog post “How long before we run out of fossil fuels?“.

When will we run out of fossil fuels?

Fossil fuels (coal, oil and gas) are finite — consume them for long enough and global resources will eventually run out. Concerns surrounding this risk have persisted for decades. Arguably the most well-known example of this was Hubbert’s Peak Theory — also known as the Hubbert curve.

M. King Hubbert, in 1956, published his hypothesis that for any given region, a fossil fuel production curve would follow a bell-shaped curve, with production first increasing following discovery of new resources and improved extraction methods, peaking, then ultimately declining as resources became depleted.4

His prediction that the United States would peak in oil production in 1970 actually came true (although it peaked 17 percent higher than he projected, and its pathway since has not followed the bell-shaped curve he predicted). This is shown in the chart with Hubbert’s hypothesized peak shown alongside actual US production data reported by the Energy Information Administration (EIA); both are measured in barrels produced per year.5

Many have attempted to apply Hubbert’s theory at not only a regional, but also a global level to answer the question: When will we run out of fossil fuels?6

Most attempts have, however, been proven wrong. During the 1979 oil crisis, Hubbert himself incorrectly predicted the world would reach ‘peak oil’ around the year 2000; and in the decades since, this prediction has been followed by a succession of premature forecasts by analysts.7

Meanwhile, actual global oil production and consumption continues to rise.

The difficulty in attempting to construct these curves is that our discovery of reserves and technological potential to extract these reserves economically evolves with time. If we look at trends in proven fuel reserves, we see that our reported oil reserves have not decreased but increased by more than 50 percent, and natural gas by more than 55 percent, since 1995. This fact, combined with changes in rates of consumption means that predicting ‘peak fossil fuel’ is highly uncertain.8

To give a static indicative estimate of how long we could feasibly consume fossil fuels for, we have plotted the Reserves-to-Production (R/P) ratio for coal, oil and gas based on 2015 figures. The R/P ratio essentially divides the quantity of known fuel reserves by the current rate of production to estimate how long we could continue if this level of production remained constant. Based on BP’s Statistical Review of World Energy 2016, we’d have about 115 years of coal production, and roughly 50 years of both oil and natural gas remaining.9

Again, these figures are only useful as a static measure; they will continue to vary with time as our capacity to economically source and extract fossil fuels changes, and our levels of consumption rise or fall.

However, whilst depleting reserves could become a pressing issue 50-100 years from now, there is another important limit to fossil fuel production: climate change. Carbon dioxide emissions remain trapped in the atmosphere for long periods of time, building up an atmospheric stock that leads temperatures to rise. To keep average global temperature increase below two degrees celsius (as has been agreed in the UN Paris Agreement), we can thus calculate the cumulative amount of carbon dioxide we can emit while maintaining a probability of remaining below this target temperature. This is what we define as a ‘carbon budget’. In the latest Intergovernmental Panel on Climate Change (IPCC) report, the budget for having a 50 percent chance of keeping average warming below two degrees celsius was estimated to be approximately 275 billion tonnes of carbon (as shown in the chart).10

Note that with each year that passes, the remaining carbon budget continues to decline—by the end of 2017, this figure will have further decreased from the IPCC’s estimates.

Here’s the crucial factor: if the world burned all of its currently known reserves (without the use of carbon capture and storage technology), we would emit a total of nearly 750 billion tonnes of carbon. This means that we have to leave around two-thirds of known reserves in the ground if we want to meet our global climate targets. However, it is important to keep in mind that this in itself is a simplification of the global ‘carbon budget’. As discussed in detail by CICERO’s Glen Peters, there is actually a variety of possible carbon budgets, and their size depends on a number of factors such as: the probability of staying below our two-degree warming target, the rates of decarbonization, and the contribution of non-COgreenhouse gases. For example, if we wanted to increase the probability of keeping warming below two degrees celsius to 80 percent, we would need stricter carbon limits, and would have to leave 75-80 percent of fossil fuels untouched.11

The quantity of fossil fuels which we would have to abandon is often referred to as ‘unburnable carbon’. According to a widely-quoted study by Carbon Tracker, there is significant potential for this unburnable carbon to result in major economic losses.12

If capital investment in carbon-emitting infrastructure continues at recent rates, it estimates that up to 6.74 trillion US$ (nearly twice the GDP of Germany in 2016) would be wasted over the next decade in the development of reserves that will eventually be unburnable. The study defines this as ‘stranded assets’.

So whilst many worry about the possibility of fossil fuels running out, it is instead expected that we will have to leave between 65 to 80 percent of current known reserves untouched if we are to stand a chance of keeping average global temperature rise below our two-degrees global target.

Fossil fuel prices

The chart shows the index of average fossil fuel prices – for coal, oil and natural gas – over the last 30 years. This index is measured relative to the year 2000, where prices in 2000 are equal to 100. The charts in the sections to follow provide more detail on the absolute price as well as changes in prices of each fossil fuel across regional sources.

Overall, we see that natural gas prices have been the least variable over this period (remaining relatively close to 100 across the last 30 years). Coal has shown the greatest volatility – rising to four times the 2000 price in 2008, and nearly 3.5-times in 2011. Oil has similarly shown volatility – varying by two to three-fold over this period.

Crude oil prices

In the chart we see the long-term trend in global crude oil prices, measured in 2016 US dollars per barrel.Overall we see strong volatility in oil prices, with significant spikes and shocks. In 2016, crude oil prices were US$43.73 per barrel – this represents a 275 percent drop in prices from 2011 when prices close to an all-time high at US$118.71.

Overall, we see that oil prices were relatively consistent throughout the 19th and first half of the 20th century, until a significant rise in prices in the 1970s. Prices spiked in 1980, reaching a high of US$107.27 before a rapid decline which coincides closely with the OPEC embargo of the early 1980s.

Oil prices later spiked again in 2008 before crashing following the financial crisis, with a later spike in 2011, falling to very low oil prices in 2016.

Oil spot prices

The visualisation shows the crude oil spot prices across various oil blends, as measured in US$ per terawatt-hours (rather than per barrel) for comparison to energy prices of coal and natural gas. As shown, the key oil blends have a closely matched spot price (despite very small differences).

In 2016, crude oil spot prices averaged around US$25 per terawatt-hour – the most expensive of the fossil fuels (as seen for coal and natural gas in the sections below).

Consumer pump prices for gasoline

Consumer pump prices for diesel fuel

Coal prices

The chart shows coal prices over the last 30 years across different regional sources, measured in US dollars per terawatt-hour. Unlike oil, where blends tend to converge on a very similar spot price, coal types can vary quite significantly. The quality of coal deposits – in terms of their carbon content – can have a notable impact on their energy density, which will determine the tonnage of coal required for a give energy output.

Natural gas prices

The chart shows natural gas prices over the last 30 years across different regional sources, measured in US dollars per terawatt-hour. Like coal, natural gas prices can vary significantly by source – this difference has been more marked over the last decade where gas from the United States can be up to five times cheaper than that in the Japanese markets.

This difference in price is partly explained by the differences in natural gas source. Accessible and economic shale gas supplies in the United States have grown dramatically over the last decade; this large supply security has leading to a significant fall in US gas prices. In contrast, much of natural gas in Asian markets is sourced as liquefied natural gas (LNG). LNG – which is compressed to form a liquid – is easier to to transport and store in a non-pressurized environment. However, this liquefaction process tends to incur a ‘sunk cost’, leading to relatively higher prices.

Employment in fossil fuels

The energy industry has historically – and continues to be, in many countries – a large source of employment. In the charts we see the long-term trends of employment in the coal industry in the United Kingdom (where large-scale coal production began) from 1873 to 2016.

Number of people employed in the coal industry

The chart shows UK coal employment in absolute numbers – this includes the number of workers contracted by the coal industry for work. In absolute numbers, employment in UK coal peaked in 1920, with nearly 1.2 million working in the industry. Since then, employment has continued to decline, reaching a low of less than one thousand workers in 2016.

Share of the workforce employed in the coal indusry

We can also visualise changes in coal employment by plotting the numbers in UK coal as a share of the total UK workforce. This change in share over time is shown in the chart. Due to changes in the total workforce numbers, UK employment peaked slightly later in percentage terms, peaking at nearly six percent in 1924. This has declined to a low of less than 0.01 percent in 2016.

In the 1920s, 1 in every 20 workers in the UK were employed in the coal industry. In 2016, this has reached a low of only 1 in every 40,000 workers.

Greenhouse gas emissions from fossil fuels

Emission factors of fossil fuels

Fossil fuels can have short-term (in the form of local air pollution) and long-term (in the form of climatic change) environmental impacts. Fossil fuels – being the dominant source of global energy production – are a key source of carbon dioxide (CO2).

However, fossil fuels can vary significantly in their relative emissions of CO2 per unit energy. To compare these differences, we use a metric called a ‘carbon dioxide emissions factor’ – which is shown for various fossil fuel sources in the chart. This is measured as the quantity of CO2 emitted (in kilograms) per unit of energy produced (in megawatt-hours). These factors are defined by the Intergovernmental Panel on Climate Change (IPCC), and are applied across global and national accounts of greenhouse gas emissions.13

Although there can be notable differences in emissions factors between different types of a given fuel (for example, differences in coal types), there are some more general trends in the relative emissions between coal, oil and gas. Typically coal produces the most CO2 per unit energy, followed by oil (which is about one-third lower than coal), and natural gas (which can produce around half the emissions of coal).

As a result, coal is often termed the most polluting of the fossil fuels. Several countries – the largest example being the United States – have therefore achieved carbon dioxide reductions in recent years by substituting coal production in its energy supply with natural gas.

Unburnable carbon

In order to meet our international climate change target of limiting global warming to 2 degrees celcius (2°C) above pre-industrial temperatures, we can emit only a limited amount of greenhouse gases. This limit on emissions is often termed our ‘carbon budget’ – a budget of much carbon we can emit if we want to achieve a given probability of limiting warming to 2°C.

This budget – to achieve a 50 percent probability of meeting our target is shown in the chart. This is measured relative to the total carbon which would be released if we were to burn all of our current known fossil fuel reserves (without the use of carbon capture and storage technology). As we explain in more detail in our blog post, we see that if we are to have any chance of keeping global average temperature increases below our 2°C target, we have to leave the majority (up to 80 percent) of our fossil fuels in the ground.14

The reserves of fossil fuels which we must leave untouched to stay within our carbon budget are often referred to as ‘unburnable carbon’. These reserves are important, not only from an environmental perspective, but also an economic one. According to a widely-quoted study by Carbon Tracker, there is significant potential for this unburnable carbon to result in major economic losses.15

If capital investment in carbon-emitting infrastructure continues at recent rates, it estimates that up to 6.74 trillion US$ (nearly twice the GDP of Germany in 2016) would be wasted over the next decade in the development of reserves that will eventually be unburnable.

Oil prices vs. consumption

Oil demand – or alternatively, consumption – is one of the key determinants of oil prices. However, as shown in the chart, and as widely discussed in the literature, oil shocks and declines are also tightly linked to distinct political and socioeconomic events.16

The chart shows the crude oil price (measured in 2015 US$ per barrel) versus global oil consumption, measured in barrels per day. Each marker represents the price-consumption values for a given year from 1965 to 2015. Key political, economic and social events have also been detailed. This chart is also available to view in interactive form, here.

Overall, we see that the sharp changes in oil price coincide with large sociopolitical events – for example, the OPEC oil embargo of 1973 led to a sharp rise in prices; the Iranian Revolution of 1979 and the 2008 financial crisis to a sharp decline; and a continued fall in prices since 2011, when US output of shale oil has been consistently growing.

Oil prices vs. consumption

Definitions & Measurement

Reserves vs. Resources: When does a resource become a reserve?

The terms ‘reserves’ and ‘resources’ are often used interchangeably. However, there is an important distinction between the two. The chart explains this distinction visually.

It is true that every reserve is a resource, but not every resource is a reserve. There are two requirements which determine whether a mineral resource becomes a reserve. The first is the degree of certainty that it exists: the planet likely has many mineral resources which we have not yet discovered. So to be defined as a reserve, we must have either a proved, probable or possible understanding of its existence. The second criteria relates to the economic feasibility of being able to access and extract the mineral resource. To be defined as a reserve, it must be economically and technologically viable to recover. If the economics are subeconomic (i.e. would result in a net loss) or marginal, a mineral resource is not defined as a reserve.

Whilst the original source of this concept – the American geologist Vincent McKelvey – visualised it as a static box, this transition between resources and reserve classifications is dynamic. As we discover previously unknown resources, and develop improved extraction technologies for economic recovery, this reserves box can grow with time (or shrink as we consume them).

Reserves vs. resources 01

Units of energy

To maintain consistency between metrics and sources, we have attempted to normalise all energy data to units of watt-hours (Wh), or one of its SI prefixes. The table shows the conversion of watt-hours to the range of SI prefixes used.

SI UnitWatt-hour (Wh) equivalent
Watt-hour (Wh)
Kilowatt-hour (kWh)One thousand watt-hours (103 Wh)
Megawatt-hour (MWh)One million watt-hours (106 Wh)
Gigawatt-hour (GWh)One billion watt-hours (109 Wh)
Terawatt-hour (TWh)One trillion watt-hours (1012 Wh)

Data Sources

BP Statistical Review of World Energy
  • Data: BP publishes data on Oil, Gas Coal, Nuclear Energy, Hydroelectricity, Renewables, Primary Energy Consumption, Electricity Generation, Carbon Doixide Emissions
  • Geographical coverage: Global – by country and region
  • Time span: Annual data since 1951
  • Available at: Online at www.BP.com

The Shift Project (TSP)
  • Data: Historical Energy Consumption Statistics and Historical Energy Production Statistics
  • Geographical coverage: Global – by country and world region
  • Time span: Since 1900
  • Available at: Both datasets are online at www.tsp-data-portal.org.

IEA – International Energy Agency
  • Data: Data on electricity, oil, gas, coal and renewables. Data on CO2 emissions (also projections)
  • Geographical coverage: Global – by country
  • Time span: Last decades
  • Available at: Online at www.iea.org
  • The IEA is publishing the World Energy Outlook.
  • You have to pay to access the IEA databases. But some data is available through Gapminder, for example Residential Energy Use (%). (for few countries since 1960, for more countries since 1971 or 1981)

Energy Information Administration
  • Data: Total and crude oil production, oil consumption, natural gas production and consumption, coal production and consumption, electricity generation and consumption, primary energy, energy intensity, CO2 emissions and imports and exports for all fuels
  • Geographical coverage: Global – by country
  • Time span: Annual data since 1980
  • Available at: Online at ww.eia.gov
  • EIA is a US government agency.

World Development Indicators – World Bank

Eurostat