6.5 Fossil Fuel Extraction and Purification

Extraction methods and their impacts

Coal is mined via surface mining (strip mining, mountaintop removal) or subsurface mining, both disturbing land and producing tailings. Oil and natural gas are extracted through drilling, including offshore rigs and hydraulic fracturing (fracking), which injects high-pressure fluid to release gas from shale. Fracking can contaminate groundwater and trigger minor earthquakes.

Purification and processing

Crude oil is refined through fractional distillation, separating hydrocarbons by boiling point into products like gasoline, diesel, and kerosene. Coal may be washed to remove sulfur and ash before combustion. Natural gas is processed to remove impurities like water, CO2, and sulfur compounds, improving efficiency and reducing pollution.

Environmental consequences

Extraction damages ecosystems through habitat destruction, erosion, and acid mine drainage, where sulfuric acid and heavy metals leach into waterways, lowering pH and harming aquatic life. Oil spills during drilling or transport devastate marine and coastal habitats. Processing and refining also release air pollutants and greenhouse gases.

Key terms

Fracking

Hydraulic fracturing; injecting high-pressure fluid into shale to release natural gas, risking groundwater contamination and earthquakes.

Fractional distillation

Process of refining crude oil by separating hydrocarbons based on boiling point.

Acid mine drainage

Runoff of sulfuric acid and heavy metals from exposed mine rock, polluting waterways and harming aquatic life.

Surface mining

Extraction method (e.g., strip mining, mountaintop removal) that removes surface layers to access coal, causing habitat destruction.

Tailings

Waste materials, including rock and minerals, left over after resource extraction from mining.

Try an AP-style question

What is hydraulic fracturing (fracking)?

1. Pumping pressurized fluid to crack shale
2. Burning oil to make steam
3. Drilling for water
4. Mining coal from mountaintops