The use of energy, which began with the use of fire and smelting metals, rapidly advanced with the invention of coal and the steam engine in the 18th century and the use of oil and natural gas in the 19th century. Fossil energy is the foundation of human civilization and the cause of environmental pollution. New approaches are needed to solve the problems of fossil energy depletion and environmental pollution.
The use of fire is an indispensable element of human civilization. In the development of tools, it was the use of fire to smelt metals that allowed us to move past the Stone Age and use bronze and iron. By using the energy of fire, we were able to overcome various constraints and grow. In the past, wood was used to smelt metals and obtain the heat energy needed for daily life. For many years, there was only gradual growth in the use of thermal energy. Then, in the 18th century, the invention of the steam engine and the use of coal led to a breakthrough in energy utilization. The improved efficiency of steam engines and the use of coal, which has a tremendous amount of energy compared to traditional wood, made it possible to convert and utilize enormous amounts of heat energy into kinetic energy. The rapid growth of humanity in the 19th century was fueled by coal, which made it possible to utilize enormous amounts of energy compared to the past. Later, in the 20th century, petroleum and natural gas led to the rapid development of civilization. Human prosperity was based on the use of fossil energy. Now, let’s take a look at the fossil energies that have led to the rapid development of human civilization.
Fossil energy, or fossil fuels, are natural resources buried underground, such as coal, oil, and natural gas. All of them are a type of organic matter that contains a lot of carbon. They are the remains of plants and animals that existed in the distant past, buried by tectonic forces and energized by the earth’s internal energy, and have been moved and transformed over the years. Its use has increased dramatically since the Industrial Revolution due to the enormous energy that can be obtained by burning it, and it is the most important source of energy that underlies modern human civilization.
Coal is a fossil energy source that is formed from plant matter and is composed primarily of carbon. When giant trees are buried and settled in the soil, soil is deposited on top of them, plant communities are formed, and the same process is repeated. When underground plant matter is subjected to high temperature and pressure, the proportion of hydrogen and oxygen decreases and the proportion of carbon increases. This phenomenon is called carbonization. Coal is categorized according to the degree of carbonization, and is divided into peat, peat, lignite, bituminous coal (bituminous coal), and anthracite. From peat to anthracite, the degree of carbonization is higher, with a higher carbon content and lower hydrogen and oxygen content. Because it is formed by the metamorphosis of plants, we often think of coal as a simple collection of organic matter. In reality, however, it shows a more complex composition. Coal is a complex mixture of maceral, a fine organic material that can be distinguished under a microscope, ash, a mixture of soil from the time of deposition, and volatile components such as sulfur and moisture, which are important for the combustion of coal along with its carbon content. In order to use coal, it needs to be processed in a series of steps, which is known as charring. This is the coal that we use.
When we think about the use of coal, we often think of briquettes, which are often seen on the news in winter, and think that coal is briquettes. Of course, briquettes are a type of coal, but they’re a much lower-quality type. Coal is a great source of energy, as evidenced by its use as a heating fuel. Coal with a good carbon content, high volatile content, and good calorific value is mainly bituminous or anthracite coal. These coals are utilized as a source of energy in thermal power plants. Coal is used as a heat source to heat boilers for power generation. The thermal energy is then used to produce steam and turn turbines to generate electricity. With the efficiency of nuclear power plants and the hope for renewable energy, coal-fired power plants can be downplayed, but their importance can be seen in the fact that coal still accounts for more than 40% of Korea’s energy generation. Another major user of coal is steel mills. At the interface between bituminous and anthracite coals, some coals have special properties, known as refining coke, which is used in steel mills to reduce iron ore to produce iron. Coal is a particularly important material for industry, and although it has been displaced as a transportation fuel since the advent of petroleum, it is still widely used as an industrial energy source.
Unlike coal, which is a solid composed of carbon, petroleum is a mixture of hydrocarbons that is produced as a liquid. It is formed by the deposition of organisms, primarily animal, that are decomposed and transformed by high temperatures and pressures in the formation, or by microbial action that transforms them into petroleum. It contains 84-87% carbon and 11-14% hydrogen, with small amounts of sulfur, nitrogen, and oxygen.
Another difference between petroleum and coal is that petroleum is geographically dispersed. The United States, South America, the Middle East, and Russia hold most of the reserves. This regional ubiquity is related to how oil is created. Because it’s a liquid, it can’t stay in the same terrain it was created in, so it migrates and forms oil fields where it can pool. They are most often found in sandstone formations, which are porous rocks that are well suited to seep oil, but not all sandstone formations, and are often found in terrain where oil is structurally isolated. An example of this is where geologic structures such as wet valleys form and have cover rocks around them that prevent oil from migrating further. These terrains are therefore explored, and if an economically viable oil field is found, it is equipped and produced. An oil field is not just liquid crude oil, like water in a bowl, but it is also trapped in pores, which are voids in the rock, like a sponge soaked in water. When a metal pipe is drilled between these rocks, the pressure in the fractured area is low, so the crude oil that exists at high pressure naturally rises through the pipe at low pressure. Traditionally, oil has been produced through these boreholes, but new technologies such as hydraulic fracturing are being introduced to reduce the pressure in the field and make it more economical.
The crude oil produced is a mixture of several hydrocarbons and other compounds. Therefore, it is necessary to remove impurities and categorize it into like components. The difference in volatility of each component in the crude oil is used to refine it. From gasoline, which is separated first due to its low boiling point, to diesel, heavy oil, liquid paraffin, petroleum jelly, petroleum jelly, and asphalt, which remains above 400 degrees Celsius. Gasoline is commonly used as fuel for passenger vehicles with gasoline engines or as a raw material for naphtha products in the chemical industry. Diesel or heavy fuel oil is used as fuel in internal combustion engines such as diesel engines and boilers. Asphalt, as it is commonly known, is used to pave roads. In recent years, processes have been developed and used to crack the hydrocarbons in polymers and convert them into gasoline, which is in high demand and has a high added value.
Natural gas is a combustible gas consisting mainly of gaseous hydrocarbons, especially methane. It is stored underground and, like oil, is produced using boreholes. Natural gas is categorized into oil field gas, gas field gas, and coal field gas depending on the production situation. Oil field gas is gas that exists alongside crude oil and is extracted along with the development of the oil field. Gas field gas is gas that has been separated from the oil field, migrated, and gathered independently in a specific geological structure. Coal field gas is gas that exists within coal seams and is released during the mining process.
Compared to liquid petroleum, it is difficult to handle and utilize, so it was used later among fossil energies. Refined natural gas has excellent value as a fuel and can be used as a clean energy source because dust, sulfur, nitrogen, etc. are removed during the liquefaction process and almost no pollutants are emitted during combustion. It is used not only as a fuel but also as an important raw material for the chemical industry. Natural gas can also be categorized into liquefied natural gas (LNG), which is refined and compressed about 600 times to liquefy it, compressed natural gas (CNG), which is compressed 200 to 250 times and stored in pressure vessels, and pipe natural gas (PNG), which is supplied through pipes.
So there you have it: coal, oil, and natural gas, the three main types of fossil energy we use. Fossil energy allows our cars and trains to run and our computers, cell phones, and other appliances to work. Fossil energy has made our lives easier than they were in the past, and it still powers our world today. We can’t imagine giving up our cars and going back to burning wood for fire. The glorious modern civilization of humanity is only possible through the use of fossil energy.
But this prosperity is not necessarily right. The use of fossil energy for human convenience and profit has led to overdevelopment and increased environmental pollution. Examples include overexploitation for resources, global warming due to massive emissions of carbon dioxide, ozone depletion due to nitrogen oxides, and acid rain and smog due to sulfur oxides. Although we are trying to prepare for environmental pollution by removing sulfur through desulfurization, removing nitrogen oxides through catalytic reactions, and using toxic substances in a cleaner form through component conversion, we are only slowing down the damage, not completely solving it.
In addition to pollution, fossil energy is showing serious signs of depletion due to its non-renewability over millions of years of formation. In fact, they are already being depleted. It is unfortunate that other energy sources, such as nuclear and renewable energy, have not been able to completely replace fossil energy. While we cannot eliminate all fossil energy for the future, the need for sustainable development will require a new approach to fossil energy. Fossil energy, which has driven the evolution of human civilization, will face new challenges in the 21st century.
