Properties & Extraction of Gas, Carbon & Coal

Instructor: Matthew Bergstresser
Fossil fuels in the form of natural gas, coal, and petroleum are used to produce electrical energy. This lesson will explain why these fuels are so useful in the generation of electrical energy, how they are formed, and how they are extracted from under the ground.

Fossil Fuels

Would you ever think that plants and animals that lived hundreds of millions of years ago give you the ability to have electricity today? The luxury of being able to turn on a light with the flick of a switch, and to have the ability to cook food without having to burn wood is most likely because of fossil fuels. Ancient organic materials (fossil fuels) are concentrated sources of stored sunlight that can be burned in power plants to generate electricity. In 2016, 65% of electric production in the United States came from the burning of fossil fuels, of which there are three major types: coal, petroleum, and natural gas. The production of the fossil fuels used today started around 300 million years ago with the death of various organic (carbon-based) material such as plants on land, and plankton in the ocean.

Production of Fossil Fuels

Coal

When land plants die, they fall to the ground and decay. Other plants die and fall on top of them. This happens over and over burying the organic material. With the correct oxygen levels, and the optimum acidity of the water, bacteria and fungi have a feeding frenzy turning the dead plants into peat. Pressure and temperature increase when peat is buried under a lot of sediment, and after roughly 200 million years, coal is formed.

Petroleum

The same process basically happens in the oceans. Plankton are microscopic plants and animals. When they die, their remains settle to the bottom of the ocean, and are buried under sediment. Eventually this organic material is under enough pressure and heat to turn the former life forms into petroleum.

Natural Gas

Natural gas is produced along with coal and petroleum. It is a natural byproduct of organic decay. Methanogens are a type of bacteria that don't use oxygen, and thrive at temperatures higher than 100 degrees Celsius. The methanogens help the dead organic material rot, and predominantly expel methane, the main component of natural gas. Because gas is less dense than rock and sediment, it rises through cracks in rocks and spaces in overlying sediment. Eventually it will get trapped under an impervious layer of rock.

Extraction

The extraction of fossil fuels begins with geologists. They study the rock types and structures that lend to the accumulation of coal, petroleum, and natural gas. They set off explosions or use machines to pound on the ground in order to set out seismic waves, which aid in providing an idea of what is under the surface. When they have evidence there is fossil fuel accumulation in an area, an exploratory well will be drilled. In order for a corporation to sell this fossil fuel, there has to be enough of it to be profitable. When the scientists and business executives are satisfied that a location contains enough of the correct type of fossil fuel, the extraction begins.

Coal Extraction

Coal is dug out of the ground using underground tunnels or by surface mining. If the coal seam (layer of coal) is near the surface, explosives are detonated breaking up the overlying rocks. They are then carried away leaving behind the coal, which can be easily extracted. This extraction process can recover around 90% of the available coal.


Surface coal mine in Mongolia
coal

If the coal is deep underground, tunnels are dug to extract the coal. This method requires that sections of the tunnels remain intact in order to hold up the overlying material while the coal is extracted. Around 40-75% of the available coal can be extracted using tunneling methods.

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