What Is Coal Used for Now?

Coal has been a crucial energy resource for centuries, and although its prominence has diminished in some respects due to environmental concerns and the rise of alternative energy sources, it still retains significant uses in various industries and applications. This article will explore the current uses of coal, highlighting its role in electricity generation, industrial processes, and other sectors. Understanding these uses is essential as we navigate the complex landscape of energy and resource utilization in the modern world.

Electricity Generation

Steam Turbine Power Plants

In a typical coal-fired power plant, coal is pulverized into a fine powder and then burned in a boiler. The heat produced from the combustion of coal boils water to create steam. This steam then drives a steam turbine, which in turn generates electricity. For example, large power plants can produce hundreds of megawatts of electricity, supplying power to millions of households and businesses. The process is relatively straightforward and has been the backbone of electricity production for decades. However, it also has environmental drawbacks as it emits significant amounts of carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen oxides (NOx), and particulate matter.

Cogeneration and Combined Heat and Power (CHP)

Some industrial facilities and district heating systems utilize coal in cogeneration or CHP plants. Here, not only is electricity generated from the steam turbine, but the waste heat from the power generation process is captured and used for heating purposes. This increases the overall energy efficiency of the system. For instance, a factory can use the heat to warm its production areas or for preheating raw materials, while also obtaining electricity for its machinery and lighting. This is especially beneficial in colder climates where heating demands are high.

Steel Production

Coking Coal

Coking coal, also known as metallurgical coal, is used to produce coke. Coke is a porous and carbon-rich material that is essential for the blast furnace in steel production. In the blast furnace, coke acts as a fuel and a reducing agent. It provides the heat necessary to melt the iron ore and also reacts with the oxygen in the ore to release the iron. The quality of coking coal is crucial as it determines the strength and porosity of the coke produced. High-quality coking coal is required to ensure efficient and continuous steel production. For example, a steel mill may source coking coal from specific mines known for their consistent quality.

By-Product Utilization

The by-products of the coking process, such as coal tar and ammonia, have their own uses. Coal tar is a complex mixture of organic compounds that can be further processed to produce chemicals like benzene, toluene, and naphthalene. These chemicals are used in the manufacturing of plastics, dyes, and pharmaceuticals. Ammonia can be used in fertilizers or in the chemical industry for various reactions. This utilization of by-products adds value to the overall coal utilization in the steel industry.

Cement Production

Fuel for Kilns

In a cement kiln, coal is burned to provide the high temperatures required for the chemical reactions to occur. The raw materials, such as limestone, clay, and shale, are heated to temperatures around 1400 – 1500 degrees Celsius. The combustion of coal supplies the necessary heat energy to drive off carbon dioxide from the limestone and to form the complex calcium silicate compounds that make up cement. A typical cement plant may consume large quantities of coal daily to maintain the continuous operation of the kilns. For example, a medium-sized cement plant might use several hundred tons of coal per day.

Quality and Emission Considerations

The quality of coal used in cement production affects the efficiency and quality of the cement produced. Low-quality coal with a high ash content can lead to problems such as clinker formation and reduced kiln efficiency. Additionally, the emissions from coal combustion in cement kilns, including SO2 and NOx, are a concern. To address these issues, modern cement plants may employ emission control technologies such as flue gas desulfurization and selective catalytic reduction to reduce the environmental impact.

Chemical and Synthetic Fuel Production

Coal Gasification

Coal gasification involves reacting coal with steam and oxygen at high temperatures and pressures to produce a synthetic gas, or syngas. Syngas is a mixture of carbon monoxide and hydrogen. This syngas can be further processed to produce a variety of chemicals. For example, it can be used to synthesize methanol, which is an important chemical in the plastics and chemical industries. It can also be used in the production of synthetic fuels like Fischer-Tropsch liquids, which can be used as diesel or jet fuel substitutes. The advantage of coal gasification is that it can potentially produce cleaner fuels and chemicals compared to traditional coal combustion, as some of the pollutants can be removed during the gasification process.

Coal Liquefaction

Coal liquefaction is another process where coal is converted into liquid fuels. Direct coal liquefaction involves breaking down the coal molecules and adding hydrogen to form liquid hydrocarbons. Indirect coal liquefaction first gasifies the coal to produce syngas and then uses the syngas to synthesize liquid fuels. These liquid fuels can supplement the existing petroleum-based fuel supply. However, both coal gasification and liquefaction processes are energy-intensive and currently face economic and technological challenges that limit their widespread commercial application.

Domestic Heating and Cooking (in Some Regions)

Household Stoves and Boilers

In some rural or less developed regions, especially where access to other energy sources is limited or expensive, coal is burned in household stoves or small boilers for heating rooms and cooking food. For example, in parts of Eastern Europe and Asia, coal-fired stoves are a common sight in winter. These stoves are relatively simple in design and can provide a reliable source of heat. However, they also contribute to indoor air pollution, which can have adverse health effects on the occupants. The use of coal for domestic purposes is gradually declining as efforts are made to improve access to cleaner energy sources such as natural gas, electricity, or renewable energy.

Safety and Environmental Concerns

The use of coal for domestic heating and cooking requires proper ventilation to prevent the buildup of harmful gases such as carbon monoxide. Additionally, the particulate matter and other pollutants emitted can affect the air quality not only indoors but also in the surrounding area. To address these concerns, there are initiatives to promote the use of cleaner-burning coal technologies or to encourage the switch to alternative energy sources for domestic use.

Other Industrial Applications

Carbon and Graphite Production

Some types of coal can be used to produce carbon and graphite products. By heating coal in a controlled environment, it can be converted into carbon electrodes, which are used in electric arc furnaces in the steel and other metal industries. Graphite, which has excellent electrical and thermal conductivity properties, can also be produced from coal and is used in applications such as batteries, lubricants, and electrodes for various electrochemical processes.

Activated Carbon

Activated carbon is produced from coal and is used for a wide range of purification and adsorption applications. It has a highly porous structure that can adsorb gases, liquids, and dissolved substances. It is used in water treatment plants to remove impurities and odors, in air purification systems to capture pollutants, and in the food and beverage industry to purify products. The production of activated carbon from coal involves processes such as activation with steam or chemicals to create the porous structure.

Conclusion

In conclusion, while the role of coal has changed and become more circumscribed in recent years due to environmental and energy market dynamics, it still has diverse and important uses. From electricity generation and steel production to chemical manufacturing and even some domestic applications, coal continues to be a significant part of the global industrial and energy infrastructure. However, efforts to mitigate its environmental impact and to develop more sustainable alternatives are ongoing, and the future of coal usage will depend on a balance between its economic advantages and the need to protect the environment.