Work and Energy: Fossil Fuels

5.3.1 Fossil Fuels

  • Fossil fuels are the remains of million-year-old plant life (coal) or aquatic animal life (gasoline and natural gas).

  • Chemical energy stored in fossil fuels is obtained through combustion.

  • Fossil fuels include coal, oil, and natural gas and are rich in hydrocarbons (molecules made up of hydrogen and carbon atoms).

  • When hydrocarbons burn, they combine with oxygen from the air to create carbon dioxide, water, and energy.

  • The general chemical equation for the combustion of a hydrocarbon, such as methane (CH4), is as follows: CH4 + 2O2 \rightarrow CO2 + 2H_2O + \text{Energy}

A. Coal

  • Coal is the most abundant fossil fuel globally, with an estimated reserve of a million metric tonnes.

  • The combustion of coal leads to significant atmospheric pollution.

B. Oil

  • Crude oil undergoes refining processes to yield various energy products, including gasoline, jet fuel, and heating oil.

  • Despite the limited global reserves of oil, it is favored over coal due to its higher energy output for the same quantity.

C. Natural Gas

  • Natural gas, often a byproduct of oil extraction, comprises a mixture of gases, primarily methane.

  • One advantage of natural gas is its ease of transportation.

Extraction and Processing

  • Fossil fuels are extracted from the Earth through various methods.

  • Coal is usually mined.

  • Oil and natural gas are often drilled and extracted from reservoirs.

  • The extracted fossil fuels may undergo refining and processing to separate impurities and obtain usable forms of the fuel.

Energy Extraction through Combustion

  • To extract energy, fossil fuels are burned in the presence of oxygen, typically in a combustion chamber or engine.

  • This combustion reaction releases energy in the form of heat.

  • The heat generated during combustion can be used to produce steam, drive turbines, or power engines.

  • In power plants, the heat produced is often used to generate steam, which in turn drives turbines connected to generators to produce electricity.

Fossil fuels are the remains of ancient plant life (coal) or aquatic animal life (natural gas, gasoline). They are rich in hydrocarbons and release energy through combustion with oxygen, creating carbon dioxide and water. The combustion of hydrocarbons, like methane (CH_4), is represented by the equation: CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O + ext{Energy}

A. Coal

  • Most abundant fossil fuel with high reserves.

  • Causes significant atmospheric pollution when burned.

B. Oil

  • Refined to produce gasoline, jet fuel, and heating oil.

  • Preferred over coal for higher energy output despite limited reserves.

C. Natural Gas

  • Primarily methane, often a byproduct of oil extraction.

  • Easy to transport.

Extraction and Processing

  • Extracted through mining (coal) or drilling (oil, natural gas).

  • Refined to separate impurities.

Energy Extraction

  • Burned with oxygen, releasing energy as heat for power generation, steam production, or engine power.