Is Jet Fuel Still Made From Coffee?

Quick answer

• No, modern jet fuel is not made from coffee beans.
• The idea of using coffee for fuel is a myth or a misunderstanding of early fuel experiments.
• Modern jet fuel is primarily derived from petroleum.
• Biofuels are being explored for aviation, but they are not coffee-based.
• The energy density of coffee is far too low for practical aviation fuel.
• While coffee grounds can be composted or used for other purposes, they are not a source for jet fuel.

Who this is for

• Anyone curious about the origins of common phrases and myths related to coffee.
• Individuals interested in the science behind fuels and energy sources.
• Coffee enthusiasts who enjoy learning interesting facts about their favorite beverage.

What to check first

Brewer type and filter type

The type of coffee maker and the filter used significantly impact the final brew. Drip machines with paper filters will produce a different cup than a French press with its metal filter, or an espresso machine. Understanding your brewer’s mechanics is the first step to diagnosing brewing issues.

Water quality and temperature

The vast majority of your coffee is water, so its quality matters. Tap water can contain minerals that affect taste, or even chlorine. Ideally, use filtered water. Water temperature is also critical; too cool and you won’t extract enough flavor, too hot and you risk burning the grounds, leading to bitterness. Aim for water between 195°F and 205°F (90°C – 96°C) for most brewing methods.

Grind size and coffee freshness

The size of your coffee grounds dictates how quickly water can extract flavor. Coarser grinds are for methods like French press, while finer grinds are for espresso. Pre-ground coffee loses its aroma and flavor compounds rapidly. For the best taste, grind your beans just before brewing. Freshly roasted beans, ideally within a few weeks of their roast date, will also yield a superior cup.

Coffee-to-water ratio

This is the foundation of a balanced brew. A common starting point is a 1:15 to 1:18 ratio, meaning for every gram of coffee, you use 15 to 18 grams of water. For example, for a 12 oz cup (approximately 355 ml or 355g of water), you might use around 20-24 grams of coffee. Experimenting with this ratio will help you find your preferred strength.

Cleanliness/descale status

A dirty coffee maker can impart stale, bitter, or even moldy flavors into your brew. Regular cleaning, especially of the brew basket and carafe, is essential. If you have hard water, mineral buildup (scale) can occur over time. Descaling your machine periodically, following the manufacturer’s instructions, is crucial for both taste and the longevity of your brewer.

Step-by-step (brew workflow)

1. Gather your equipment: Ensure your coffee maker, filter (if applicable), grinder, and brewing vessel are clean and ready.

• What “good” looks like: All parts are clean and free from old coffee residue or mineral buildup.
• Common mistake: Using a dirty carafe or brew basket. This will impart stale flavors. Always rinse or wash after each use.

2. Measure your coffee beans: Weigh your whole beans using a digital scale for accuracy.

• What “good” looks like: Precise measurement based on your desired coffee-to-water ratio.
• Common mistake: Eyeballing the amount of coffee. This leads to inconsistent brews. Invest in a simple kitchen scale.

3. Heat your water: Heat filtered water to the optimal brewing temperature range (195°F – 205°F or 90°C – 96°C).

• What “good” looks like: Water is hot but not boiling, ideally measured with a thermometer or kettle with temperature control.
• Common mistake: Using boiling water. This can scorch the coffee grounds, creating a bitter taste. Let boiling water sit for about 30-60 seconds before pouring.

4. Grind your coffee beans: Grind your beans to the appropriate size for your brewing method, just before brewing.

• What “good” looks like: A consistent grind size that matches your brewer type (e.g., coarse for French press, medium for drip).
• Common mistake: Using pre-ground coffee or an inconsistent grind from a blade grinder. This results in uneven extraction and poor flavor.

5. Prepare the filter (if applicable): Place your paper filter in the brew basket and rinse it with hot water.

• What “good” looks like: The filter is fully wet, and the rinse water has been discarded. This removes paper taste and preheats the brewer.
• Common mistake: Forgetting to rinse the paper filter. This can leave a papery, unpleasant taste in your coffee.

6. Add coffee grounds: Place the freshly ground coffee into the prepared filter or brewing chamber.

• What “good” looks like: The grounds are evenly distributed.
• Common mistake: Tamping down the grounds too much or leaving them unevenly distributed. This can lead to channeling, where water bypasses some grounds.

7. Bloom the coffee (for pour-over/drip): Pour just enough hot water to saturate all the grounds, then wait 30 seconds.

• What “good” looks like: The grounds expand and release CO2, forming a “bloom.”
• Common mistake: Skipping the bloom phase. This allows for better degassing and a more even extraction.

8. Begin brewing: Slowly and steadily pour the remaining hot water over the grounds in a controlled manner, ensuring all grounds are saturated.

• What “good” looks like: A steady flow of brewed coffee into the carafe or mug, with no overflowing or dry spots.
• Common mistake: Pouring water too quickly or unevenly. This can lead to under-extraction or over-extraction in different parts of the coffee bed.

9. Allow to finish brewing: Let the water fully pass through the grounds and drip into the carafe.

• What “good” looks like: The brewing process has completed, and the coffee is ready to serve.
• Common mistake: Leaving the coffee to sit on a warming plate for too long. This can “cook” the coffee, making it taste burnt and bitter.

10. Serve and enjoy: Pour your freshly brewed coffee into a mug and savor the aroma and taste.

• What “good” looks like: A delicious cup of coffee that meets your expectations.
• Common mistake: Letting the brewed coffee sit for extended periods. Coffee is best enjoyed fresh.

Common mistakes (and what happens if you ignore them)

Mistake	What it causes	Fix
Using stale or old coffee beans	Flat, dull, or bitter taste; lack of aroma.	Buy freshly roasted beans and store them in an airtight container away from light and heat.
Incorrect grind size	Under-extracted (sour, weak) or over-extracted (bitter, harsh) coffee.	Match grind size to your brewing method: coarse for French press, medium for drip, fine for espresso.
Water temperature too low	Under-extraction, resulting in a weak, sour, and underdeveloped flavor.	Use water between 195°F and 205°F (90°C – 96°C).
Water temperature too high	Over-extraction and scorching, leading to bitterness and astringency.	Let boiling water cool for 30-60 seconds before brewing.
Inconsistent coffee-to-water ratio	Coffee that is too strong or too weak, lacking balance.	Use a kitchen scale to measure both coffee and water accurately.
Dirty brewing equipment	Stale, rancid, or moldy flavors in your coffee; potential health hazard.	Clean your brewer, grinder, and carafe regularly with soap and water or a descaling solution.
Skipping the bloom phase (pour-over)	Uneven extraction, trapping CO2 and leading to a less flavorful cup.	Pour a small amount of water to saturate grounds and wait 30 seconds for degassing.
Leaving coffee on a warming plate	“Cooked” coffee taste, bitterness, and a burnt aroma.	Transfer brewed coffee to a thermal carafe or drink it immediately.
Using tap water with strong flavors	Off-flavors in your coffee, masking the natural taste of the beans.	Use filtered water or bottled spring water.
Inconsistent pouring technique	Channeling (water finding paths of least resistance) leading to uneven extraction.	Pour water slowly and steadily, ensuring even saturation of all coffee grounds.

Decision rules (simple if/then)

• If your coffee tastes sour, then you likely under-extracted it because the grind was too coarse or the water was too cool.
• If your coffee tastes bitter, then you likely over-extracted it because the grind was too fine or the water was too hot.
• If your coffee tastes weak, then you may need to increase the coffee-to-water ratio or ensure your grind is fine enough for your brewer.
• If your coffee has a papery taste, then you forgot to rinse your paper filter before adding grounds.
• If your coffee tastes stale, then your beans are too old or have been improperly stored.
• If your brewer is producing a slow drip, then the grind might be too fine, or the machine needs descaling.
• If your coffee has an oily residue on top, this can sometimes be a sign of over-extraction or coffee that has been left on a hot plate too long.
• If you’re using a French press and get sediment in your cup, then your grind is likely too fine, or you’re pressing the plunger too hard.
• If your espresso machine is making sputtering noises, then the water temperature might be too low, or the puck is too loose.
• If your coffee tastes “off” and you can’t pinpoint why, check the cleanliness of your grinder and brewer first.
• If you want a stronger cup, try using slightly more coffee or a slightly finer grind, but adjust one variable at a time.
• If you want a less intense cup, try using slightly less coffee or a slightly coarser grind, again, adjusting one variable.

FAQ

Is it true that jet fuel used to be made from coffee?

No, this is a persistent myth. Modern jet fuel is overwhelmingly derived from petroleum. While there have been experiments with biofuels for aviation, none of them are derived from coffee beans.

Why does this myth persist?

The origin of this myth is unclear, but it might stem from early experiments with various organic materials for fuel or a misunderstanding of how different substances can be processed. Coffee’s energy content is far too low to be a practical fuel source for aviation.

What is modern jet fuel made of?

Modern jet fuel, such as Jet A and Jet A-1, is primarily a refined kerosene-based product derived from crude oil. It’s designed for high energy density and stable combustion at high altitudes.

Are there any biofuels used in aviation?

Yes, there are biofuels being developed and used in aviation, often blended with traditional jet fuel. These are typically made from sources like vegetable oils, animal fats, or algae, not coffee.

Can coffee grounds be used for anything else?

Absolutely. Used coffee grounds are great for composting, can be used as a natural exfoliant in skincare, or even as a pest deterrent in gardens. They are not, however, suitable for making jet fuel.

How does coffee’s energy content compare to jet fuel?

Coffee has a very low energy density compared to petroleum-based fuels. It would take an enormous volume of coffee to produce the energy needed for even a short flight, making it entirely impractical as an aviation fuel source.

What’s the best way to store coffee beans?

Store whole beans in an airtight container, away from light, heat, and moisture. Avoid refrigerating or freezing them, as this can introduce moisture and unwanted odors.

How often should I clean my coffee maker?

It’s recommended to clean your coffee maker daily or after each use. Descaling, which removes mineral buildup, should be done every 1-3 months, depending on your water hardness and usage.

What this page does NOT cover (and where to go next)

• Detailed chemical composition of various jet fuels.
• Next: Research aviation fuel standards and specifications.
• Specific energy density calculations for different organic materials.
• Next: Explore resources on thermodynamics and fuel science.
• The history of alternative fuel development beyond coffee.
• Next: Look into the history of biofuels and sustainable aviation initiatives.