Coal as an Energy Source, Is It Renewable or Nonrenewable?
Coal, oil, and natural gas are fossil fuels and are nonrenewable resources. This means that they cannot be replenished at a rate fast enough to compete with other natural resources, such as biomass, wind, hydropower, and solar. In fact, coal and other fossil fuels take millions of years to replenish in natural conditions, making them non-renewable energy resources.
A non-renewable resource takes a long time to form. Millions of years ago (400 million years ago), Earth’s surface was covered in lush vegetation and swamps. As the plants died out, they sank to the bottom of the swamps, where the exclusion of air and light, as well as high pressure, slowly turned these plant remains into fossil fuels as we know them today.
These non-renewable energy sources include:
- oil and
- natural gas:
Non-renewable resources have one thing in common: they all pollute the environment a lot. This pollution comes from burning them: when you burn fossil fuels, such as coal, you release harmful greenhouse gasses. These gasses stay in the atmosphere for a long time and pollute the air, water, and soils. The best alternative to non-renewable resource use is renewable resources and nuclear energy.
Coal – takes millions of years to form. It is made of plant material that has been exposed to millions of years of immense heat and pressure. Under these conditions, the plant remains mineralized, giving us the coal as we know it today.
Oil – the liquid-equivalent of coal, oil represents liquified remains of plant and animal organisms. All the oil we have today was formed millions of years ago, locking the carbon from the atmosphere and locking it below the Earth’s surface. Oil is a great source of energy and is used for:
- Electricity generation,
- Powering our vehicles,
- Making plastics, and
- Making different chemical compounds, such as rubber, asphalt, and petroleum jelly. Believe it or not, even CDs and DVDs are made of oil.
Natural gas – natural gas is the last kind of fossil fuel that is used worldwide. It is an excellent source of energy and is used for propelling vehicles, heating, cooling, and cooking. It is usually found in the vicinity of petroleum oil deposits.
Unlike non-renewable energy sources, a renewable resource is readily available to be used and can be replenished by nature within a short period of time. Renewable resources are the new-age energy sources that do not dig or drill into the Earth’s surface, do not pollute the environment, and can give us abundant renewable energy on demand. The only issue with renewable energy sources is that they are intermittent and not as energy-dense as coal.
Furthermore, one of the biggest obstacles in having large-scale renewable energy generation was, until recently, the price of the elements every such project should have. Luckily, with advances in technology, almost every renewable energy source can be tapped into and turned into power plants. The price of this type of energy source has fallen up to 80% in the past decade, so wind and solar energy are now cheaper than making new coal power plants.
Renewable energy sources include:
- Solar power,
- Wind energy,
- Tidal energy,
- Wave energy, and
- Biomass energy.
Solar Power – the energy of the sun is used worldwide to generate electricity (in solar PV modules) and to heat water (solar collectors). Sun is the most abundant energy source we have. Solar in the US is on the rise, especially with the renewable energy portfolio demanding more power from renewable resources.
Wind energy – everybody is familiar with windmills using this energy source to generate power. Traditionally, it has been used in mills. Today, it helps mitigate climate change by reducing our reliance on fuel extraction. There are many large-scale wind farms, especially in Texas.
Hydropower – mostly in the form of dams, hydropower was the first renewable source of electricity on Earth. Hydropower comes in the form of large-scale hydro projects and mini-hydropower plants capable of supplying electricity to a few households only. There are many large hydro dams in the US.
Tidal Energy – the energy of the tides is only experimentally being used to power homes around the world. The reliability of this energy source ensures high investment. However, not all areas are suited for this type of energy generation.
Wave Energy – waves are easy to predict, always available, and they pack a punch – a small wave-electricity generator can make as much electricity as a large wind turbine. Most of the US, Europe, parts of Africa, and Australia are all suited to use wave energy for power generation.
Biomass – biomass is all the dead plants and their remains that are burned for heat and electricity production. Alternatively, these dead plants can also be put in aerobic digesters (great for heat recovery and CO2 capture – the output of the process is compost) and anaerobic digesters (the output is hummus and biogas (containing methane, which can be burned for power generation, CO2 recovery, and heating)).
Besides these, there are other energy sources that do not pollute nature or pollute less than coal. The main energy source among these, helping make around 8% of the world’s electricity, is nuclear power. This energy is non-renewable but is still considered green since there are no nasty CO2 emissions.
What is Coal?
Coal is a fossil fuel. It was formed millions of years ago, deep under the Earth’s surface. There, the immense heat and pressure helped mineralize dead plants and animals in a process that lasted well over a million years. Coal is a non-renewable resource, as it cannot be replenished in a human lifetime. It is rich in carbon but pollutes a lot. Burning a single pound of coal releases 2 pounds of CO2 – double the rate of natural gas burning.
Coal is typically found under the Earth’s surface, where it was deposited millions of years ago. It is brought back to the surface by mining. There are shallow coal mines or surface coal mines, which can typically be used to mine coal up to 300 feet deep. For deeper deposits, deep mining is used. This mining technique is much more expensive and riskier, but it can bring coal from up to 1,000 feet deep.
Turning Coal into Electricity
Turning coal into electricity is a pretty straightforward process. Once the mining is complete, the coal is transferred to a thermal power plant. This type of plant burns coal. The heat that is released is used to boil water in a special chamber called the boiler. As the water is heated, it evaporates, and the steam that is generated is used to propel turbines. Turbines, in turn, turn the generator, and electricity is generated.
The electricity is then sent through a transformer, which turns DC (Direct Current) into AC (Alternating Current), which can then be transported over vast distances. The biggest flaw of the system is that it has an efficiency of around 40% – the majority of the energy that is released can never be recovered. This means that most of the coal around the world is never turned into power – it is lost in the form of CO2 and other harmful substances that are released into the atmosphere.
Over a million years ago, as coal was formed, the carbon from the atmosphere was locked in the form of mineralized dead plants. As the carbon was pulled from the atmosphere and locked under Earth’s surface, the atmosphere changed and started supporting life as we know it today. However, mining and bringing all that carbonized plant material back to the surface of the Earth changes the atmosphere again and causes climate change.
However, carbon is not the only problem we see with mining coal. Air pollution, surface water pollution, and pressure changes underground all take their toll on nature. As the rock substance known as coal is removed, vast areas remain ruined, plants find it difficult to repopulate the area, and animals flee in search of new homes. As people produce more power from coal, pollution that contains many chemical substances is released into the atmosphere. The smoke released from power plants contains the following chemicals:
- SO2 – Sulfur dioxide causes lung issues,
- NOx – different oxides of nitrogen also cause lung issues and form smog when mixed with water in the air,
- CO – carbon monoxide, a deadly gas,
- CO2 – carbon dioxide, a harmful greenhouse gas,
- Heavy metals, very toxic, get deposited in human, animal, and plant tissues, causing irreversible damage,
- Ash – acidifies the soil, reducing yields and food quality.
Advantages & Disadvantages of Coal
Coal, as an energy source, has both advantages and disadvantages it can offer to us. As coal is a part of everyday life, it pays off to learn more about it. Advantages of using coal for heat and electricity generation include:
- Ease of access,
- The technology for mining (both surface mining and deep mining) is known and available, and extraction models proven,
- Coal is cheap – however, solar power and wind power have gotten cheaper than coal, crude oil, or gas in the past decade,
- Coal is a natural battery that is stored underground – the same cannot be said of renewable resources.
There are many disadvantages of coal-burning as well:
- Mining can be tricky, dangerous and it can devastate entire regions,
- Locked in carbon is brought back to the surface, causing climate change,
- It has a severe impact on human, animal, and plant life and health,
- It cannot be naturally replenished – once it’s gone, we cannot make any more coal,
- It acidifies the rain, surface water, soils, and air and has detrimental effects on the environment.
Is coal same as charcoal?
No, coal and charcoal are not the same. Coal is a calorie-rich mineral that takes millions of years to form. Charcoal, on the other hand, is a product of burning wood in a low-oxygen environment. Sometimes, some coal is added to charcoal to increase the temperature it burns, but the two products are not the same.
Why we should stop using coal?
Coal is the biggest CO2 emitter in the world. Of all the non-renewable energy sources, coal is the worst for the planet, with 0.9 lbs of CO2 released for every pound of coal that is burned. In addition to this, burning coal emits large amounts of PM2.5, PM5, and PM10 particles that are very harmful to humans.
Is coal short for charcoal?
No, coal is not short for charcoal. Charcoal is produced by burning biomass (such as wood) in low-to-no-oxygen environments. Coal, on the other hand, is made over millions of years of pressure and heat and is a type of mineral. So, while coal is made by nature, charcoal is man-made.
How long will coal last?
Coal reserves in the USA should last for another 470 years at current exploitation rates. However, our reliance on coal has to be completely removed if we want to save the climate. Coal is the biggest emitter of CO2 gasses of all the non-renewable energy sources. Coal alternatives, such as natural gas, biogas, and biomass, pollute much less and are much easier to replenish.
Underground deposits of coal in the US are enough for another 470 years of extraction at the current pace. However, the question is whether we should keep doing so or not. Switching to renewable energy, helping mitigate climate change, and preserving the environment should all be prioritized on our renewable agenda. Switching to renewables and nuclear (uranium) energy is the sure way to both secure a reliable supply of energy and that we produce no more pollution.