We occasionally grill out, and we were wondering what’s the difference between coal and charcoal. I couldn’t find a good answer out there, so I did some more digging. Here’s what I found.
Coal is a rock made from compressed ancient plants, while charcoal is pieces of burned wood leftover from an incomplete fire. Since coal is made over millions of years, it’s nonrenewable. However, charcoal is easily produced and is renewable. Coal should not be used in grills or to cook over, but charcoal is fine.
|Temperature||2,500ºF to 4,500ºF||1,200ºF|
|BTUs||12,500 per pound||9,000 per pound|
|Burn Time||5-6 hours||2-5 hours|
|Cost||$259 per ton||$1,200 per ton|
So, while coal and charcoal are fairly different, how are they made, and how are they best used? Let’s take a closer look.
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How Coal and Charcoal Are Made and Used
Millions of years ago, before dinosaurs, the earth was covered by large swamps. Over time, dirt and water covered these swamps.
Compressed by the weight and heat of the earth, these plants turned into dense rocks, called coal.
Since coal is highly condensed plant matter (mostly carbon), it makes sense why it burns so well.
While coal is a type of rock, it’s made from plants, so it’s different than mineral rocks such as gemstones. Coal is considered to be sedimentary rock, or rocks made close to Earth’s surface.
Coal was used sparingly until the 1700s when coal mining started in Virginia. After the 1800s, coal was found to be an easy fuel source, especially when heating homes, and it grew in popularity.
The 4 different types of coal, ranked in quality, are:
- Anthracite – Often called “hard coal”, anthracite coal is 85-97% carbon. It’s harder, denser, and more lustrous than the other types of coal. As a result, it offers the best and cleanest burn, leaving behind little soot and tar.
- Bituminous – The second-best type of coal. Bituminous coal is blocky and appears smooth and shiny at first, but has alternating small shiny and dull layers. This coal has a high BTU value and is often used to generate electricity and manufacture steel in the US.
- Subbituminous – Unlike the above, subbituminous coal is dull and not shiny. It doesn’t have as hot or efficient of a burn as bituminous coal, but subbituminous coal is still used to generate electricity.
- Lignite – Also called “brown coal”, lignite coal is the lowest grade coal as it has the least amount of carbon and contains high moisture content. As a result, lignite coal has a low value when it comes to heating, but it’s still used in electricity generation.
Much of the coal deposits are located in North America and today it’s used to power almost half of the electricity in the US. This process is done by burning coal to heat water—creating steam—which turns turbines and generates electricity.
What is Coke (Coal Product)?
Coke is a fuel that’s made by heating coal with little to no-oxygen. This reduces its moisture and makes it a more stable and reliable fuel.
Coke fires are hotter and used in steel manufacturing to provide steel with more flexibility and strength, great for bridges, buildings, and cars.
The process of making coke involves baking coal in an oven for 12-36 hours at 1,800ºF to 2,000ºF. This burns away impurities such as coal gas, carbon monoxide, methane, tars, and oil. The result is a material with few impurities and high carbon content (coke).
Charcoal is naturally created when a fire doesn’t fully burn the wood. Typically, this is from fires that have low oxygen and as a result, don’t have enough heat to consume all of the fuel.
There are 3 types of charcoal:
- Lump Charcoal – Made directly from hardwood with little to no processing. The average burn time for lump charcoal is around 2-3 hours.
- Briquettes – Made by compressing charcoal, wood products such as sawdust, binders such as starch, and other additives. Briquettes usually burn for an average of 4-5 hours.
- Extruded Charcoal – Made by extruding, or compressing raw or carbonized wood into logs. Unlike briquettes, extruded charcoal does not use a binder.
When you buy charcoal from the store, it’s usually either lump charcoal or briquettes. If you buy briquettes, they’re often made from wood, peat, coal, coconut shell, or petroleum (or a combination of the above).
When burning wood at home, charcoal is often created by accident by restricting the airflow to the fire. This usually happens because the air intake to the fireplace or wood stove isn’t open wide enough.
If you find this to be the case, simply adjust the air intake on your appliance until you have a balance of a fire that doesn’t burn too fast or slow.
Although, some people purposefully create and harvest charcoal as it’s a great fuel to use for future fires. Especially if you need hotter fires such as a forge. This is due to its carbon content of around 50-95%.
Coal contains heavy metals and other contaminants, which is a large reason why coal mining is considered to be a dangerous job. Burning coal in a grill releases these materials and can negatively affect the food and us.
For best results, use lump charcoal or briquettes that have little to no coal or other additives.
Gas grills are another good option as most if not all of the gas is burned off when heated.
Due to its higher carbon content and compactness, coal burns hotter than charcoal. This is especially true for anthracite coal.
Coal fires can get up to 4,500ºF.
For example, coal is often used to melt iron, which melts at 2,800ºF.
But since most factory materials and equipment are unable to withstand that heat, steam generation (for electricity) is limited to about 1,000ºF.
On the other hand, charcoal grills get up to 1,200ºF, due to a lower carbon content, less compaction, and higher moisture content.
Keep in mind that oxygen is a vital component when it comes to a fire’s heat, so a coal or charcoal fire will be limited without proper intake.
When it comes to BTUs, coal offers about 12,500, while charcoal has 9,000. For context, wood has a BTU value of about 7,000.
The burn time for coal is about 5-6 hours, while charcoal is about 2-5 hours. This depends on the type of coal and charcoal. For example, anthracite coal burns for much, much longer than lump charcoal.
As you can see from the temperature and burn time, coal is a superior fuel compared to charcoal and wood. It makes sense why coal is widely used (and difficult to replace) in utilities such as electricity generation.
Since coal is widely available and in copious amounts from its creation millions of years ago, it’s a cheap fuel, costing about $259 per ton. However, this may change as the availability of coal decreases.
For example, it’s estimated that we’ll have enough coal for the next 70-150 years (see below).
On the other hand, charcoal costs $1,200+ per ton as it needs to be manufactured. However, few order charcoal at this scale.
Most of the charcoal purchased is in small 10-20 lb bags from the store. These typically cost around $10-$20.
Coal is not environmentally friendly due to it being nonrenewable and its harsh effects of mining, transporting, and burning. It also contains impurities such as sulfur and nitrogen, which are released into the air when burned. These impurities combine with water vapor (clouds) and form “acid rain”.
Fortunately, technology today can filter out 95-99% of these particles from burning coal. Other measures are being taken to reduce the effects of mining and transporting, but more improvements are needed.
Since charcoal is made from surface trees (and not fossilized ones), it requires much less time to create, making it significantly more renewable.
However, while charcoal is renewable, it doesn’t mean it’s sustainable. Since charcoal is made from wood, they’re tied to the same renewability timeline.
If you’d like more information, I wrote a post about firewood and if it’s renewable/sustainable, so make sure to check it out.
Recommended: Is Firewood a Renewable Resource? Answered