Coal Explained

coal

Coal: the main source of energy we humans have been using for hundreds of years. Cavemen used it for warmth, Native Americans used it to cook and make clay pots, and both the union and confederacy used it to make weapons in the American civil war. For almost as long as man has existed, coal has been right there along with him. It has produced many progressive achievements and failures, but also the demise of our green Earth. Coal, when burned, is incredibly harmful to the environment, let's find out why.



 

What is coal? 
The World Coal Association defines coal as “a fossil fuel and [it] is the altered remains of prehistoric vegetation that originally accumulated in swamps and peat bogs. The energy we get from coal today comes from the energy that plants absorbed from the sun millions of years ago.”  Plants that are living hold solar energy through a process we know as photosynthesis. When a plant dies it begins to decay, usually, it releases this energy. Coal began to form between 360 million and 290 million years ago. The build-up of silt together with movements in the earth's crust (tectonic movements) buried swamps and peat bogs. When they were buried, plant materials were exposed to high temperatures and pressure. This caused physical and chemical changes in the vegetation, transforming it into peat and then into coal.

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How do we mine coal?
Coal is mined through two methods: surface or ‘opencast’ mining or underground or ‘deep’ mining. The choice of mining method depends on the geology of the coal deposit.  The surface mining method recovers more of the coal deposit than underground mining. In this method of mining, all coal seams (deposits of coal) are exploited. More than 90% of coal can be recovered. Large opencast mines can cover an area of many square miles and they use very large pieces of equipment. Draglines, shovels, trucks, bucket wheel excavators, and conveyors are all used to mine coal and all are massive. First, all of the soil and rock above the seams are broken up with explosives. Then, it is removed by draglines or shovel and truck. After that, the exposed seam is drilled, fractured and mined into strips. Finally, the coal is loaded onto trucks and then gets taken to preparation plants or directly to where it will be used.

Underground mining has two different methods, one is room-and-pillar mining and the other is longwall mining.  Room-and-pillar mining is when coal deposits are mined by cutting a network of ‘rooms’ throughout its and leaving pillars to support the roof of the mine.  These pillars can take up to 40% of the coal in the seam. Longwall mining is also underground, but a lot more coal is mined in this method. Longwall mining involves the full extraction of coal from a section of the seam or ‘face’ by using mechanical shearers (machines that cut coal off the face). The face can be anywhere from 100 meters to 350 meters. Mechanical supports hold up the roof while the coal is being extracted, which is why more coal can be mined; the supports aren’t parts of the seam. But because of this, when all available coal has been removed, the roof is allowed to collapse.

What do we use coal for?
Although coal may not be as visible today as it was in the early 1900s, it is even more prevalent as a source of fuel. “Coal production has increased by more than 70 percent since 1970. If you use electricity, chances are that you are a coal consumer. Nine out of every ten tons of coal mined in the United States today is used to generate electricity. About 56 percent of the electricity used in this country is coal-generated electricity.” Generating electricity is just one of the many uses for coal in the United States. “Manufacturing plants and industries use coal to make chemicals, cement, paper, ceramics, and metal products. Methanol and ethylene, which can be made from coal gas, are used to make products such as plastics, medicines, fertilizers, and tar.” Certain industries consume large amounts of coal. Concrete and paper companies burn coal, and the steel industry uses coke and coal by-products to make steel for bridges, buildings, and automobiles.  

Why is coal bad for the environment?
The larger surface mines can reach up to 70 feet deep. Mountaintop removal and valley fill mining has affected large areas of the Appalachian Mountains, and landscape and streams sometimes get covered with rock and dirt. The water draining from these filled valleys contains pollutants that can harm aquatic life downstream. Underground mines have a much smaller environmental impact compared to surface mines. However, mine tunnels do sometimes collapse, and acidic water will then drain from the mine. Also, methane gas that is in coal seams can explode if concentrated in underground mines. This coalbed methane must be vented out of mines to make mines safer places to work. In 2015, methane emissions from coal mining and abandoned coal mines accounted for about 10% of total U.S. methane emissions and 1% of total U.S. greenhouse gas emissions (based on global warming potential). Some mines capture and use or sell the coalbed methane extracted from mines.

Several principal emissions result from coal combustion:

  • Sulfur dioxide (SO2), which contributes to acid rain and respiratory illnesses.

  • Nitrogen oxides (NOx), which contribute to smog and respiratory illnesses.

  • Particulates, which contribute to smog, haze, respiratory illnesses and lung disease.

  • Carbon dioxide (CO2), which is the primary greenhouse gas produced from the burning of fossil fuels (coal, oil, and natural gas.)

  • Mercury and other heavy metals, which have been linked to both neurological and developmental damage in humans and other animals.

  • Fly ash and bottom ash, which are residues created when coal is burned at power plants.

What can you do?
A lot of people don’t realize how much of what they do requires burning coal--everything that involves electricity involves coal. About 25% of the electricity we use at home goes to power our lights, and the solution to this is not rocket science, in fact, it's the exact opposite. Turn your lights off! It is probably the easiest thing in the world, just flip the switch when you leave the room. But wait, there's more! Use LED lights! They use 70% less energy than a light bulb and last 25 times longer, it’s a win-win for you and the environment. Unplug your electronics when you're done using them or when they’re fully charged. Computers and other electronics consume 40% of their total energy use when they’re turned off but still plugged in. Weatherstrip the windows and doors, this keeps out cold as well as hot air. Insulate your home, this way your house will be much more protected from the outside weather and you won't have to turn the heat or air conditioning on. 

There's a lot we can do to curb interest in coal and move to renewable energy. We just have to work together and take the necessary steps to make it happen.

Sources: 1, 2, 3, 4, 5, 6, 7, 8

Posted by Max Wix on Jun 24, 2018 3:00 PM America/Chicago

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