In this blog post, we will shed light on the benefits and future challenges of how fossil energy, which has led to the development of human civilization, has caused environmental problems.
The use of fire is an essential element in the development of civilization. The development of tools from the Stone Age to the Bronze Age and the Iron Age was made possible by the smelting of metals using fire. The use of fire allowed people to overcome various limitations and grow. In the past, wood was used to smelt metals and obtain the thermal energy needed for daily life. The use of thermal energy has only grown gradually over the years. Then, in the 18th century, the invention of the steam engine and the use of coal made it possible to use energy in a revolutionary way. With the improvement in efficiency due to the improvement in the structure of the steam engine and the use of coal, which has a tremendous amount of energy compared to existing wood, it became possible to convert and use enormous thermal energy into kinetic energy. In the 19th century, coal enabled the rapid growth of humanity by providing access to a vast amount of energy. In the 20th century, petroleum and natural gas led to the rapid development of civilization. The prosperity of humanity was based on the use of fossil fuels. Now, let’s take a look at fossil fuels that have led to the rapid development of human civilization.
Fossil energy or fossil fuels refer to natural resources buried underground, such as coal, oil, and natural gas. All fossil energy is a kind of organic matter aggregate that contains a lot of carbon. It is an energy source formed by the remains of plants and animals that existed in the distant past being buried by tectonic activity and undergoing a long process of migration and transformation while receiving energy from the interior of the earth. Since the Industrial Revolution, the amount of fossil energy used has increased dramatically due to the advantage of being able to obtain a huge amount of energy by burning it. Fossil energy is the most important energy source that forms the foundation of modern human civilization.
Coal is a fossil energy source formed by plant matter and mainly consists of carbon. When huge trees are buried and submerged in the soil, soil is deposited on top of them, and the same process is repeated after the formation of plant communities, and when the plant matter gathered underground is subjected to high temperature and high pressure, the hydrogen and oxygen components decrease and the carbon component ratio increases. This phenomenon is called carbonization. Coal is distinguished according to the degree of carbonization, and is divided into peat, peat, lignite, bituminous coal (anthracite), and anthracite. The higher the degree of carbonization, the more the coal is transformed from peat to anthracite, and it has a high carbon content and low hydrogen and oxygen content. Since it is formed by the metamorphism of plants, it is often thought that coal is a collection of simple organic matter. However, in reality, it shows a more complex composition. Maceral, a fine organic component of coal that is distinguished by a microscope, soil components (ash) that have been mixed in since the time of deposition, and volatile components, sulfur, and moisture, which are important in addition to the carbon content in the combustion of coal, are all combined to form coal. Therefore, a series of processing steps are required to use coal, which is called coal preparation. The coal that has gone through the coal preparation process is what we use.
When we think about the use of coal, we often think of the volunteer scene of sharing coal briquettes that we often see on the news in winter, and we think that coal is just coal briquettes. Of course, coal briquettes are also a type of coal, but they are just a type of coal with a rather poor quality. As can be inferred from the appearance of briquettes used as heating fuel, coal is an excellent energy source. Coal with excellent carbon content and high volatile components that show good calorific value is mainly bituminous coal or anthracite. Such coal is used as an energy source in thermal power plants. Coal is used as a heat source to heat power generation boilers. Steam is produced using thermal energy, and the turbines are rotated to finally produce electrical energy. The power generation efficiency of nuclear power plants and the hope for renewable energy may make us take coal-fired power plants lightly, but considering that coal still accounts for more than 40% of Korea’s energy generation, we can guess how important they are. Another place that mainly uses coal is steel mills. There are some coals with special characteristics at the boundary between bituminous and anthracite coals, which are called refining cokes and are used in the process of producing iron by reducing iron ore in steel mills. Coal is a particularly important material in industry, and although it has been replaced as a transportation fuel since the advent of oil, it is still widely used as an industrial energy source.
Unlike solid coal, which is made of carbon, petroleum is a mixture of hydrocarbons that are produced in liquid form. It is mainly formed when animal-derived organisms are deposited and decomposed and metamorphosed by high temperatures and pressures in the earth’s crust, or when they are metamorphosed into petroleum by the action of microorganisms. Such oil contains 84-87% carbon, 11-14% hydrogen, and a small amount of sulfur, nitrogen, and oxygen.
Another difference between oil and coal is that oil is geographically dispersed. Most of the reserves are held by the United States, South America, the Middle East, and Russia. This regional unevenness is related to the principle of oil generation. Since oil is in liquid form, it cannot remain in the same place where it was generated, and it forms oil fields where it can move and accumulate. Oil is mainly found in sandstone layers, which are porous rocks suitable for oil seepage, but this is not the case for all sandstone layers, and it is mainly found in topographically isolated areas. For example, a geological structure such as a fold is formed, and there is a layer of cover rock around it that prevents oil from moving any further. Therefore, we explore this terrain and, if we find an economically viable oil field, we set up facilities to produce oil. Oil is not just liquid crude oil in a bowl like water, but rather, it is trapped in the voids of the rock like a sponge full of water. When a metal pipe is installed between these rocks through drilling, the pressure in the fractured part is low, so the crude oil that was under high pressure naturally rises up through the pipe under low pressure. Traditionally, oil has been produced through such boreholes, but new technologies such as hydraulic fracturing are being introduced due to the pressure drop in oil fields due to continuous production and the need to secure economic feasibility.
The crude oil produced is a mixture of various hydrocarbons and other compounds. Therefore, it is necessary to remove impurities and classify them by the same components. It is refined by using the difference in the volatility of each component in crude oil. From gasoline, which has the lowest boiling point and is separated first, to diesel, heavy oil, liquid paraffin, petrolatum, and asphalt, which remain at temperatures above 400 degrees Celsius, are separated. Gasoline is commonly used as fuel for passenger cars with gasoline engines or as a raw material for products in the chemical industry. Diesel and heavy oil are used as fuel for internal combustion engines such as diesel engines and boilers. Asphalt is commonly used in road paving. Recently, a process has been studied and used to break down polymeric hydrocarbons and convert them into gasoline, which is in high demand and has high added value.
Natural gas refers to a combustible gas whose main component is hydrocarbon gas, especially methane. Since it is stored underground, it is produced using boreholes like oil. Natural gas is classified into oil field gas, gas field gas, and coal field gas depending on the production conditions. Oil and gas are produced from the same source, and oil and gas are found together and are extracted together with oil during oil field development. Gas from oil fields is separated from oil fields, moved, and gathered independently in specific geological structures. Coalbed gas is gas that is released during coal mining in coal seams.
Compared to liquid petroleum, it was used later than other fossil fuels because it was difficult to handle and use. Refined natural gas has excellent value as a fuel, and dust, sulfur, nitrogen, etc. are removed during the liquefaction process, so it can be used as a clean energy source because it emits almost no pollutants when burned. It is used not only as a fuel but also as an important raw material for the chemical industry. Natural gas in its gaseous state is refined, compressed to about 600 times its original volume, and liquefied into Liquefied Natural Gas (LNG), compressed to 200-250 times its original volume and stored in pressure vessels as Compressed Natural Gas (CNG), or supplied through pipes as Pipe Natural Gas (PNG).
In this article, we have looked at the fossil fuels that we mainly use: coal, oil, and natural gas. Fossil fuels have made it possible for cars and trains to run, and have made the use of home appliances such as computers and mobile phones a matter of course. Fossil fuels are the reason why we can live more conveniently than in the past, and they are still moving the world even at this very moment. We cannot imagine giving up cars and starting to use firewood to make a fire again. Modern civilization and its brilliant human society have been made possible through the use of fossil fuels.
However, this prosperity is not always right. As a result of using fossil fuels for the convenience and benefit of humanity, issues of indiscriminate development and environmental pollution have arisen. Examples include indiscriminate development for resource acquisition, global warming due to the massive emission of carbon dioxide, the destruction of the ozone layer by nitrogen oxides, and acid rain and smog caused by sulfur oxides. They try to prepare for environmental pollution by removing sulfur through desulfurization devices, removing nitrogen oxides through catalytic reactions, and removing toxic substances through component conversion, but these measures only delay greater damage and do not provide a complete solution.
In addition to environmental pollution, fossil fuels are showing serious signs of depletion due to their non-renewability, which is the result of their formation over millions of years. In fact, they are being depleted. Nevertheless, it is regrettable that other energy sources such as nuclear energy and renewable energy have not completely replaced fossil energy. It is not possible to eliminate all fossil energy sources immediately for the sake of the future, but a new approach to fossil energy is needed in terms of the need for sustainable development. Fossil energy, which has led the evolution of human civilization, will face new challenges in the 21st century.
