Coal energy represents the main source of power and heat on planet Earth, even today when mankind struggles to reduce the level of air, water and soil pollution.
To reduce air, soil and water pollution on the planet, we have to develop the generation capacity for renewable energy, and also to replace the conventional vehicles with electaric ones.
Even if it is considered the most affordable energy source for electricity generation and heating, coal is also the dirtier source of power available for us. Let’s see what are the advantages and disadvantages of coal energy.
Coal is used today on a mass scale, and is responsible for the massive air pollution created by coal-fired power plants, the pollution of the soil and water (the ash resulted when burning coal sits around the coal power station).
When burned, coal produces heat, but also some chemical substances such as carbon dioxide, sulfur dioxide, nitrogen oxides, mercury and particulate matter.
All these substances leak into water, soil and air, producing smog, soot, acid rains and toxic emissions, which leads to global warming and climate change.
All these harmful emissions are responsible for the large number of asthma attacks, chest pains, breathing problems, lung and heart diseases and a large number of deaths produced yearly.
The most deaths due to air pollution are recorded in countries where coal is the main source of electricity and heat during the winter.
Coal Definition
Coal is a brownish-black or black sedimentary rock that was formed over millions of years from organic materials such as dead plants and animals due to the high pressure and heat present in the underground layers of rock.
Being a combustible rock, coal burns in air and the steam resulted is used to spin a turbine and generate electricity with the help of a generator.
Coal is also used for residential heating and cooking in countries where natural gas or other forms of cleaner power are not available or are too expensive for the local population.
Some sectors of the industry also use coal for energy and heat generation, which leads to additional air, soil and water pollution that affects the life of the people living in the neighborhood of these factories.
Advantages of Coal
Coal has many advantages compared to other sources of energy.
1. Is a very abundant resource on planet Earth
The coal resources on our planet can be found in almost every country.
The highest coal deposits are located in the U.S., Russia, China and India, and the resource is so abundant that we can use coal to generate energy and for residential heating at least by the end of the century.
However, the major development of the renewable energy generation capacity on the planet will prematurely end the use of coal as an energy source even before depleting the coal resources available on the planet.
2. Is one of the cheapest sources of power
If we ignore the pollution costs generated by coal as an energy source, we can say that this fossil fuel is not only very abundant, but is also a very affordable (cheap) source of energy.
This would be the reason why developing countries like China and India rely mostly on coal to develop their economies forgetting that this cheap fossil fuel, is also a very unhealthy source of power.
3. Is a cheap source of power with high energy density
Despite the fact that is one of the cheapest fuels available today, coal has a pretty decent energy density compared to other fuels.
The following list shows the energy density of different types of coal compared to the most common fuels used today.
Energy Density of Different Fuels
1. Coal
Coal 29.3 MJ/kg (Megajoules per kg).
Charcoal 28.8 MJ/kg.
Bituminous coal 30 MJ/kg.
2. Wood
Wood 17.6 MJ/kg
Wood pellets 15.8 MJ/kg
3. Liquid fuels
Crude oil 45 MJ/kg.
Diesel fuel 50 MJ/kg.
Gasoline 47 to 49 MJ/kg.
Liquified natural gas 35 MJ/kg.
Ethanol 29.8 MJ/kg.
Methanol 20 MJ/kg.
4. Gaseous fuels
Natural gas 43 MJ/kg.
Hydrogen 142.5 MJ/kg.
5. Paper
Paper 20 MJ/kg.
6. Switchgrass
Dried switchgrass 16.75 MJ/kg.
7. Solid waste
Polystyrene 40 MJ/kg.
Municipal garbage 12 MJ/kg.
Cow dung 15 MJ/kg.
8. Nuclear fuels
Uranium-235 (235U): 8 x 10^7 MJ/kg.
Compared to the other fuels used on a mass scale on the planet, coal features a pretty high energy density despite its low price.
4. Coal is a continuous source of power
Compared to solar and wind power, coal is a dirty energy source, but at the same can provide a continuous supply of energy and heat, which is used both in the industry and for residential heating.
If the coal supply is ensured, a coal-fired power plant can work 24/7 to produce energy.
5. Clean coal technology can reduce the emissions produced by coal power stations
Clean coal technology refers to the modern technology used to capture and store the carbon dioxide produced by a coal-fired power plant, which would reduce the level of harmful emissions produced by the plant.
However, despite the benefits brought to the coal sector, the clean coal technology is not very widely spread today, mostly because it only increases the energy consumption of the power plant and is also quite expensive.
However, liquid coal burns cleaner than the rock itself.
Coal liquefaction (also called “Coal to X”) is the process used to convert coal into useful liquid hydrocarbons such as liquid fuels and petrochemicals.
Liquid coal is mostly used in the transportation industry, but also as a petroleum substitute.
Coal in liquid form is used like other alternative liquid fuels such as methanol and dimethyl ether (DME).
We can find liquid coal in lubricants, synthetic waxes and also in several chemical feed stocks.
6. Coal energy works together with renewable energy
Nowadays, the energy used inside your home cam be produced from a variety of energy sources.
Solar and wind power are intermittent sources of energy becaue solar power works only during the day, and wind power only when the wind is strong enough to spin the the turbine.
Solar and wind energy need to be paired with reliable sources of energy such as coal energy to cover the energy demand in the grid during peak hours.
Disadvantages of Coal
The drawbacks of coal are generated by its disastrous effect on the environment and on the human health.
1. Is a finite resource
We already know that we have enough coal deposits on the planet to generate energy and heat for at least another two centuries.
However, coal is a finite resource that one day will be exhausted, and this is the reason why we can’t consider coal an energy source of the future where mankind will mostly rely on renewable energy, which is an endless resource.
2. Is the main contributor to climate change
Burning coal generates carbon dioxide, sulfur dioxide, nitrogen oxides, mercury, lead and particulate matter and all these substances are polluting our waters, soil and air, producing smog, soot, acid rains and toxic emissions.
All these harmful emissions produced by coal can cause asthma attacks, chest pains, breathing problems and lung cancer.
Children are the most affected by the fact that coal is still used as a main source of energy and heat on our planet.
The pollution produced by coal contains toxic mercury that can damage the nervous system, and is very dangerous for babies and young children which can develop mental problems if they live in an area where coal is burned.
Coal power station generating energy and polluting the air, image source: pixabay.com
After burning coal, the waste resulted (ash) is also bad for our health. Coal ash is stored in thousands of pits across the U.S.
Living close to a coal ash pit will affect your life and your health in one way or another pretty soon.
3. Mining coal destroys the landscape
In mountain top removal mining, coal companies will first clear cut the forest on the hill or mountain, and will literally destroy the tops of the mountains using strong explosives. to get the coal.
This way the mountain is consumed and flattened, which changes the landscape.
Mining coal this way dumps millions of tons of waste into the streams and poisons the fresh water reserves.
Mining coal also affects the life of the workers involved in the coal sector.
4. Is a toxic and outdated energy source
Coal is a cheap source of energy, which could be useful in developing countries, but because it is the most toxic of all fossil fuels it is considered a very dangerous resource.
Mankind started to mine coal from the late 18th century, which means that this source of power is old and outdated.
The future society can no longer rely on an energy source that besides being outdated, it is also destroying the environment and the human health.
5. Produces high transporting costs
Mining coal can be cheaper for coal companies, but the trip made by coal from the mine to the coal fired power plants is another business.
The coal produced in the mines contains impurities which lowers its quality and its usefulness, so the coal is sent for enrichment to remove those impurities and convert it into a high quality commercial product.
From there, coal is shipped to the clients using trains and large ships.
All these activities are generating additional costs with this fossil resource.
6. Coal mines are destroying habitats and are responsible for social relocation
The mining activity is known for destroying the forests located in the area of the mines.
Mining company clean the terrain destined for mining by destroying forests and habitats, which will banish all the birds and animals living there.
Established communities living close to the mine need to be relocated to avoid the massive pollution of the soil, water and air produced by the mining activity.
Why Clean Coal Is Only A Myth?
Even if many people involved in the energy sector are considering ‘clean coal’ as a cleaner source of energy (which could keep coal in the energy mix of the future), we can say that clean coal is still coal.
Clean coal is actually regular coal that is handled in a different manner in the process of producing energy from coal, and the term ‘clean coal’ mostly refers to clean coal technologies.
Clean coal technologies were created to lessen a number of pollutants released in the production of energy from coal.
Clean coal technologies
1. Carbon capture and storage
Using this technology, carbon dioxide released while burning coal is separated from the air that leaves the power plant using a process called “absorption” or carbon scrubbing.
A group of chemicals called amines are used to bind to the carbon dioxide and pull it out from the air.
The removed CO2 is then piped underground and stored (sequestered).
Another idea to stop the CO2 from reaching the atmosphere, is to store the gas in liquid form on the bottom of the oceans (liquid CO2 is denser than water).
However, none of these ideas seem to work for a very long period of time because we don’t know what the stored CO2 will do in the underground or in the oceans after decades, hundreds or thousands of years.
We have to stop considering coal as a source of energy and heat because is extremely harmful for the environment and our health.
2. Washing the sulfur out of coal before entering the power plant
The idea consists of using a coal preparation plant where coal is turned into smaller chunks to be introduced into a water tank where minerals like magnetite are used to increase the density of the water.
The coal starts floating because it has a smaller density than the liquid inside the tank, and while washing the coal, the sulfur and other impurities are removed reaching the bottom of the tank.
The “cleaned coal” is then sent to the power plant and burned for energy and heat generation with less emissions.
3. Oxy-fuel combustion
Oxy-fuel combustion is another clean coal technology that reroutes the flue gas back into the plant (when coal is burned at a power plant, the exhaust called “flue gas” is usually released into the atmosphere).
After rerouting the flue gas back into the plant, it is paired with pure oxygen and used to burn more coal.
They use pure oxygen instead of air because air contains a large amount of nitrogen, which if it is heated with coal will reduce its efficiency and will produce more nitrogen byproducts.
The oxy-fuel combustion technology produces hotter temperatures and generates more energy.
However, even using this technology will not turn the coal power plant into a green power plant.
Emissions will be somehow reduced this way, but the pollution of the water, soil and air will still be present in the areas where coal-fired power plants are located.
The clean coal technologies raise more issues because they consume more energy and they are also expensive.
Adding a carbon capture and storage unit to a coal-fired power plant will only increase the coal consumption, while the energy output will remain the same.
Final conclusion
Coal is an energy source of the past that will remain in the history of mankind only as a major polluter of the planet, which was mostly used only in the childhood of humanity.
In a not very far future from now on, coal will no longer represent a viable energy source for mankind because the energy mix of the planet will consist only on low-carbon energy sources and renewable energy.
