Suitable for A Level, IB, IGCSE, GCSE students and teachers of Geography
In Part 1, I looked at the importance of energy and how economic and human development depends on it. We need it to lift the remaining 770 million people in extreme poverty (Level 1) to Level 2 and beyond. We need it to lift the people currently in Levels 2 and 3 to Level 4. If people living at Level 4 at the moment want to keep living their lives with high life expectancies and great access to educational opportunities and the expectation of finding a good job in a well run economy then they will need a continued steady supply of enough energy to keep them there.
Putting aside energy for transport for now, I’ll concentrate on electricity and its production. There are many sources of electrical energy. Here is a list of sources under two categories, non-renewable and renewable:
Non-renewable
Oil
Natural Gas
Coal
Nuclear (Uranium)
Uranium Image.
Renewable
Solar power
Wind power
Tidal power
Wave power
Hydroelectric power (HEP)
Geothermal power
Biomass
The first three sources in the non-renewable list (oil, natural gas & coal) are called fossil fuels. This is because they are formed over millions of years through the decomposition of organic matter, sediment deposition and changes through heat and pressure. Large parts of coal for example are made up of ancient former rainforests and swamp like environments with large amounts of carbon content.
Let’s explore the formation of these fossil fuels in more detail.
Oil & Natural Gas Formation
Image source: https://lms-leicester.libguides.com/c.php?g=807815
Oil and natural gas are formed through the accumulation of organic matter including microscopic marine plants and animals in oceans and lakes. Over time layers of sediment cover the organic material preventing it from decomposing completely. Heat and pressure increase due to the Earth’s geothermal gradient. Physical and chemical changes (diagenesis) transform the organic material in a waxy substance called kerogen. With further burial and higher temperatures, the kerogen undergoes a process called catagenesis. This process involves the thermal cracking of the complex organic molecules in the kerogen, breaking them down into simpler hydrocarbon molecules. As the organic matter undergoes catagenesis, the resulting hydrocarbons, including oil and natural gas, become more fluid and less dense than the surrounding rocks. This causes them to migrate through porous rocks, such as sandstone or limestone, and accumulate in reservoirs.
Coal formation
Just as with oil and natural gas, coal is formed of organic matter. They build up in bogs, marshes and swamps. The lack of oxygen in these environments means there is only partial decomposition of the plant matter. Peat is formed with a high water content. See image below:
Source: https://soils.org.uk/blog/restoring-scottish-peat-to-combat-climate-change-an-update-from-cop26/
Once Peat is formed, further buriall and compaction occur and more heat and pressure is applied over time - pressure from the layers of soil and rock above and heat from the geothermal gradient with increasing depth towards the Earth’s interior.
Concentrated abundant stored energy
Through the processes outlined above, Earth has been endowed with abundant deposits and reservoirs of fossil fuels. Using these resources has helped humanity to reach unprecedented levels of human development with record lows of extreme poverty. Their use does not come without problems though. The next article will look at the benefits and problems of fossil fuel use.
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