Types of fossil fuels

Fossil fuels refer to coal, oil, natural gas and other non-renewable fuel resources buried underground and under the ocean. Fossil fuels are divided into coal, petroleum, oil shale, natural gas, oil sands, and combustible ice under the sea in the order of the amount of buried energy.
1. Coal
Coal is formed by plants buried in the ground under the action of underground and geothermal heat. After tens of millions or even hundreds of millions of years of carbonization, the oxygen content is reduced after releasing gases such as water, carbon dioxide, and methane. Organic matter in coal is a complex polymer organic compound, mainly composed of elements such as carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorus, and is very rich in carbon. Due to the different geological conditions and the degree of evolution, the carbon content is different, so the calorific value is also different. According to the order of calorific value, it is divided into anthracite, semi-anthracite, bituminous coal and lignite. Coal is widely distributed on the earth and does not concentrate in a certain place of origin.
Coal is a complex mixture, mainly containing carbon, in addition, it also contains hydrogen and a small amount of elements such as nitrogen, sulfur, oxygen and inorganic minerals.
2. Petroleum
Oil extracted from oil wells is called crude oil, which is a viscous liquid. Petroleum contains mainly two elements, carbon and hydrogen.
Oil is the accumulation of microbial debris in water, forming hydrocarbons under high pressure. Petroleum can be refined to obtain gasoline, kerosene, diesel and heavy oil. Oil is unevenly distributed across the globe, with the Middle East accounting for 54%, North America 12%, and South America 9%, accounting for almost three-quarters of identifiable deposits.
Oil is the most used fossil fuel in the world, and it takes a slower time to run out than the others. Widespread availability of renewable energy sources such as fertilizer generation, high-energy nuclear power generation, and continuous scientific progress can reduce dependence on fossil fuels. In addition, petroleum usage is high because it is a raw material for petrochemical products and has a wide range of uses.
As suggested by the conceptual principles of supply and demand, when the supply of fossil fuels falls, prices rise. Therefore, when the price of fossil fuels is high, there will be more energy options, and renewable energy, which was generally considered uneconomical, will become one of the energy sources that are more economical. At present, although the required cost and processing technology of artificial gasoline and other renewable energy are higher and more complicated than that of ordinary oil production, the economic benefits in the future will be higher than that of ordinary oil production.
3. Oil shale
Oil shale is formed after the carbonization of algae, and contains too much ash, most of which cannot be self-refined. Oil sands are sands containing 4-20% heavy oil. Oil shale and oil sands are abundant in the American continent.
4. Natural gas
Natural gas is primarily a gaseous hydrocarbon composed of carbon and hydrogen, the most important of which is methane.
Natural gas is directly mined underground and mainly contains methane. It is cooled at minus 162 degrees Celsius, and after being liquefied, it is transported as liquefied natural gas by large-scale special ocean ships or oil tanks. The distribution of natural gas is also very skewed towards the Middle East, the Americas and continental Europe.
5. Combustible ice
Combustible ice is a combustible substance found in the solid form of methane stored in the deep sea.