Fossil Fuels: Coal and Oil Formation, Uses, and Impacts
Fossil Fuels: Coal and Oil
Regarding energy, consider fossil fuels: carbon, petrochemicals, and natural gas. Currently, 78% of the commercial energy used worldwide comes from the combustion of fossil fuels. This process produces serious problems of contamination and increases the greenhouse effect due to CO2 emissions and other gases. However, we cannot ignore them until we have alternative energy sources. The sun is a possible alternative. We are gradually replacing fossil fuels with other cleaner energies that have a lesser impact on our environment.
Coal Formation and Characteristics
The coal: Coal is a sedimentary rock of organic origin, composed of amorphous carbon hydrocarbons, organic compounds, plant proteins, and inorganic materials. Coal formed from the accumulation of plant remains at the bottom of swamps and lagoons. In the absence of oxygen, these remains underwent a carbonization process due to fermentation reactions caused by bacteria acting on cellulose and lignin.
As the plant matter decomposed, it lost oxygen and hydrogen atoms, transforming into methane and CO2, leaving a deposit with a high carbon percentage. This process formed peat. To accelerate this process, burial is necessary to prevent the putrefaction of plant remains. Subsequently, compaction occurs due to pressure from successive layers, with increasing temperature culminating in carbonization. The carbon remains buried under other waterproof clay layers.
Different types of coal are classified according to their carbon content.
Peat is not truly coal but the first stage of coal formation, with a low carbon and high moisture content. Lignite is a poor-quality coal with a carbon content of about 60%. Coal has about 80% carbon, and anthracite coal has the highest carbon content, around 90%, and the maximum calorific value. Additional heat and pressure can transform charcoal into graphite, which is pure carbon.
Approximately 78% of carbon is used for combustion. Carbon is abundant and has a very high heat output, but it is also dirty, and its high sulfur content is a primary cause of acid rain. The main use of carbon is its combustion in thermal power plants to produce electricity. Currently, it is impossible to eliminate these plants, but efforts are underway to reduce their sulfur emissions through washing and other technologies.
Oil Formation and Characteristics
Oil: Oil is a mixture of gaseous, liquid, and semi-liquid hydrocarbons that originates from organic remains. Due to its fluid nature, it resides in the pores of certain sedimentary rocks. Oil formed from the mass death of marine plankton due to changes in temperature or water salinity in a three-stage process:
Accumulation
Organic remains form from phytoplankton living in surface waters, primarily in deltaic areas where the waters are rich in nutrients.
Burial
As the plankton dies, it sinks to the bottom. Much of the remains are destroyed, but a small part reaches the bottom. Even there, it can continue to be destroyed by scavengers and decomposers. This accumulation is facilitated when we are in anaerobic conditions, making it difficult for organic matter to oxidize and preventing the life of scavenger organisms.