Power and Energy Production in the World
Senior 6 · Geography
Power and Energy Production in the World
Lesson 1 of 4
25 min
Figure 1 is a source to analyse, not just a picture. It shows where the world's electricity came from in 2024, according to the International Energy Agency (IEA). Before you read on, answer three questions from the chart alone: Which single source produced the most electricity? What share came from the three fossil fuels together? Which group of sources is growing fastest, and how could you find out?
Figure 1: World electricity generation by source, 2024. Data: IEA electricity statistics.
Two lessons stand out. First, coal, natural gas and oil still produced of the world's electricity in 2024. Second, electricity is only part of energy use: transport runs mainly on oil, and many homes cook with wood or charcoal. The IEA notes that fossil fuels have supplied around four fifths of the world's total energy for decades (IEA, World Energy Outlook 2023). This lesson studies the non-renewable sources that dominate that supply.
Definition
Energy resource: anything in nature from which people obtain useful energy, such as coal, flowing water or sunlight.
Non-renewable resource: a resource that forms far more slowly than it is used, so that its stock runs down as it is consumed. Example: crude oil, which took millions of years to form.
Fossil fuel: a fuel formed from the buried remains of plants and micro-organisms by heat and pressure over millions of years: coal, petroleum (crude oil) and natural gas.
Primary energy: energy in the form in which it is found in nature (coal, crude oil, wind). Secondary energy: energy converted into a more useful form, such as electricity or petrol.
Installed capacity: the maximum power a power station can deliver, in megawatts (MW). Generation: the energy it actually produces over a period, in megawatt-hours (MWh) or terawatt-hours (TWh; ).
Coal forms from plant matter that collected in swamps, was buried before it could rot, and was then compressed and heated. As burial deepens, the material passes through a series of stages, each with more carbon and less water: peat → lignite (brown coal) → bituminous coal → anthracite. Anthracite gives the most heat per tonne.
Rwanda's link. Rwanda has no workable coal, but it does have peat, the first stage of coal formation. Rwanda Energy Group (REG) reports up to 155 million tonnes of dry peat in bogs covering about 50 000 hectares, mostly near the Akanyaru and Nyabarongo rivers and the Rwabusoro plains. It is burned in the 15 MW Gishoma plant in Rusizi District and the 70 MW Hakan plant in Gisagara District (REG, Least Cost Power Development Plan, 2024 Review, published 2025).
Petroleum and natural gas form mainly from microscopic marine plankton, not from dinosaurs. The plankton settled in mud on the sea floor, which became an organic-rich source rock. At depths of a few kilometres, heat slowly "cooked" the organic matter into oil and, at higher temperatures, gas. Being lighter than water, they migrated upwards through porous rock until an impermeable layer stopped them. A trap is a structure that holds them: an anticline (an upfold, Figure 2), a fault, or a salt dome.
Figure 2: An anticline trap. Gas, the lightest, collects at the crest; oil lies below it; water fills the pores lower down.
Methane under Lake Kivu. Rwanda's own gas does not lie in rock traps but is dissolved in the deep water of Lake Kivu, which Rwanda shares with the DR Congo. Water is pumped up, the gas bubbles out as the pressure falls, and it is burned to make electricity. REG reports that the 26 MW KivuWatt plant has run since 31 December 2015 and that Shema Power Lake Kivu in Rubavu District has a 56 MW agreement with REG. Because the methane is used much faster than it forms, REG treats it as non-renewable.
A nuclear power station makes heat by fission: the nuclei of uranium-235 atoms split when struck by neutrons, releasing energy and more neutrons in a controlled chain reaction. The heat raises steam, which drives turbines, as in a coal station, but without burning anything. Uranium is mined mainly in Kazakhstan, Canada and Namibia, and in Niger. Nuclear power gave 8.9% of world electricity in 2024, and 66.7% of France's (IEA, 2024 data). Africa's only nuclear power station is Koeberg, near Cape Town in South Africa; Egypt is building a second at El Dabaa.
| Source | Main advantages | Main disadvantages |
|---|---|---|
| Coal | Large reserves spread over many countries; cheap where mined near the surface; steady (base-load) power | Highest carbon dioxide per unit of energy; air pollution and acid rain; open-cast mines destroy land |
| Petroleum | Liquid, easy to transport and store; very high energy per litre; powers almost all vehicles | Unevenly distributed, so prices swing with politics; oil spills; carbon emissions |
| Natural gas | Burns more cleanly than coal or oil; gas stations start up quickly to meet peaks | Needs pipelines or costly liquefaction (LNG) to move; leaks of methane, a strong greenhouse gas |
| Nuclear | Huge output from little fuel; almost no carbon dioxide while running; steady power | Very high building cost and long construction; radioactive waste; risk of accidents such as Chernobyl (1986) and Fukushima (2011) |
Worked example 1: analysing an energy-mix source
Problem. Using Figure 1, world generation in 2024 was about 31 600 TWh. (a) What percentage came from fossil fuels? (b) Estimate how many TWh coal produced. (c) What percentage came from low-carbon sources (nuclear plus renewables)?
Solution.
(The IEA's exact figure is 10 894 TWh; the small gap comes from rounding the percentage.)
plus part of the 0.8% "other" (geothermal and tide). Interpretation: about three fifths of world electricity is still fossil-based, so the energy transition is far from complete.
Worked example 2: how long will a reserve last?
Problem. An illustrative country has proven oil reserves of 1 500 million barrels and produces 0.20 million barrels a day. Calculate its reserves-to-production (R/P) ratio, and explain why the oil may in fact last longer or shorter than this.
Solution. First convert production to a yearly figure.
The ratio assumes that production and reserves stay constant. The oil could last longer if new fields are discovered or better technology recovers more oil from old ones; it could last a shorter time if production rises to meet growing demand.
Warning
Common mistakes. (1) Mixing up power and energy: a 70 MW plant is a capacity; what it produces in a year is measured in MWh or GWh. (2) Saying oil comes from dinosaurs: it comes mostly from marine plankton. (3) Calling Lake Kivu methane renewable: it does re-form, but far more slowly than it is extracted. (4) Thinking nuclear power is a fossil fuel: it burns nothing and releases almost no carbon dioxide while it runs, but uranium is still a non-renewable resource.
Tip
Exam technique. When a question says "assess" or "evaluate" an energy source, give advantages AND disadvantages, support each with a named place (Garzweiler, the Niger Delta, Koeberg, Lake Kivu) and finish with a judgement: for whom, where and when the source is a good choice.
Bozeman Science: "Fossil Fuels", presented by Paul Andersen. Watch for how coal forms from land plants but oil and gas from marine plankton, and for the ways each fuel is extracted.
Practice
Summary
Sources and credits
Photos: Garzweiler surface mine, October 2018 (Martin Falbisoner, CC BY-SA 4.0) and Methane extraction platform at Lake Kivu (U.S. Department of the Treasury, public domain), via Wikimedia Commons.
Video: "Fossil Fuels", Bozeman Science, embedded from YouTube.
Figures 1 and 2, the text, worked examples and exercises: written by Ganzaa.
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.
