Each time when I travel by plane that’s for me an extreme life adventure. Simply because I am in the situation when I can not be anymore in full control of my life. I can only trust the science and knowledge of the few other people that surely must have a better knowledge than me about how to handle that science. These people are the Cabin Crew and they have knowledge in driving a plane. Therefore in this post let me tell you the story of kerosene, the liquid that makes you fly.
I love to fly but everytime I do this I feel a sort of emotions mixed with insecurity. I am already used with it, but not matter how much I try to pretend that everything is fine, that feeling of insecurity is always there as long as I am not on the ground. So it all starts from the moment I am already in my seat in the plane. For me every flight is a new excercice, but the feelings about insecurity are similar. For example when I fly from Brussles to New York, it happens like this: As soon as the aircraft doors closed, and we pushed back from the gate at Brussles Airport, a voice announced the beginning of the pre-flight safety briefing as follows:
“Good afternoon, ladies and gentlemen, and welcome to this Delta Airlines flight to New York. Before our departure, may we have your attention while the cabin crew point out the safety features aboard this aeroplane.”
Now let me break this down: I always find this a disconcerting way to start a flight. I am convinced that it’s a fake: that the safety briefing isn’t really about safety at all. For a start, they fail to mention the tens of thousands of liters of aviation fuel on board. It is the enormous amount of energy contained in this liquid that allows us to fly at all; its fiery nature is what powers the jet engines that they’re capable of taking, in our case from Belgium to the USA, 300 passengers in a 250-ton aircraft from a standing start on the runway to a cruising speed of 800 km/h, and to a height of 12.000 m, in a matter of minutes. The sheer awesome power of this liquid fuels our wildest dreams. It allows us to soar above the clouds and travel anywhere in the world in a matter of hours. It’s the same stuff that took the first astronaut, Yuri Gagarin, into space in his rocket, and that fuels the latest generation of SpaceX rockets, which fire satellites into the atmosphere. It is called kerosene.
Kerosene = is an oil, often called paraffin oil or heating oil. Is a thin, clear, flammable liquid formed from hydrocarbons obtained from the fractional distillation of petroleum. Kerosene is derived primarily from petroleum, but at one time, it was also made from coal, tar and shale oils. It can appear colorless or pale yellow and has a unique odor. The term kerosene is in fact, derived from the Greek word “keros” for wax. Sometimes spelled kerosine or kerosiene, it is also called coal oil because of ist asphalt origins.
Kerosene is therefore a transparent, colourless fluid that, confusingly, looks exactly like water. So where is all that hidden energy stored, all that hidden power? Why doesn’t the storage of all that raw energy inside the liquid make it appear, well, more syrupy and dangerous? And why is it not mentioned in the pre-flight safety briefing?
If you were to zoom in and have a look at kerosene on the atomic scale, you would see that its structure is like spaghetti. The backbone of each strand is made of carbon atoms, with each one bonded to the next. Every carbon is attached to 2 hydrogen atoms, except at the ends of the molecule, which have 3 hydrogen atoms. At this scale you can easily tell the difference between kerosene and water. In water there isn’t a spaghetti structure, but rather a chaotic jumble of small V-shaped molecules (1 Oxygen atom attached to 2 Hydrogen atoms, H2O). No, at this scale kerosene more closely resembles olive oil, which is also comprised of carbon-base molecules all jumbled up together. But where the strands in kerosene are more like spaghetti, in olive oil they’re branched and twirled.
Because the molecules in olive oil are a more complex shape than the ones in kerosene, it’ s harder for them to wiggle past each other, and so the liquid flows less easily – in other words, olive oil is more -viscous than kerosene. They’re both oils, and on an atomic level they look relatively similar, but, because of their structural differences, olive oil is gloopy while kerosene pours more like water, This difference doesn’t just determine how viscous these oils are, but also how flammable.
The Persian physician and alchemist Rhazes wrote about his discovery of kerosene in his 9th-century Book of Secrets. Rhazes became interested in the naturally occurring springs of the region, which oozed not water, but a thick, black, sulphurous liquid. At the time, this tar-like material was extracted and used on roads, essentially as an ancient form of asphalt. Rhazes developed special chemical procedures, which we now call distillation, to analyse the black oil, He heated it up and collected the gases that were expelled from it. He then cooled these gases down again, whereupon they transformed back into liquid. The first liquids he extracted were yellow and oily, but through repeated distillation they became a clear, transparent and free-flowing substance – Rhazes had discovered kerosene.
At the time Rhazes couldn’t have known the full extent of what this liquid would ultimately contribute to the world, but he did know it was flammable and that it produced a smokeless flame. While this may seem like a trivial discovery now, creating indoor light was a major problem for every ancient civilization. Oil lamps were the most sophisticated light-producing technology of the day, but up until then burning oil often produced as much soot as it did light. Smokeless oil lamps would be a revolutionary innovation, so much so that their importance is immortalized in the story of Aladdin, from The Book of 1001 Nights.
In the story, Aladdin finds an oil lamp, a magic lantern. When he rubs it, he releases a powerful genie. Genies occur frequently in myths of the time, and are said to be supernatural creatures made from a smokeless fire; this particular genie is bound to do the bidding of the person who owns the lamp – an immense power. The significance of the new liquid and its ability to create a smokeless flame could not have been lost on the alchemist Rhazes. So why didn’t the Persians start using this new spirit? The answer comes, in part, from the importance that olive trees had in their economy and culture.
In the 9th century, olive oil was the fuel of choice for oil lamps in Persia. Olive trees thrived in the region, were drought-tolerant and yielded olives, which could be pressed into oil. It took about 20 olives to create a teaspoon of olive oil, which provided one hour of light with a typical oil lantern. So, if an average household needed 5 hours of light per evening, it would go through 100 olives a day, or approximately 36,000 olives a year, just for one lamp.
To produce enough oil to light their empire, the Persians needed an abundance of both land and time, because olive trees generally, don’t produce fruit for 20 years. The Persians also needed to protect their land from anyone who might want to take this valuable resource, which meant they needed organized towns, and this required still more olives so everyone could have both cooking oil and light. To support an army they needed to pay taxes, and in Persia paying taxes often meant giving the government a percentage of your olive oil crop. So, you can see, olive oil was central to Persian society and culture, as it was to all Middle Eastern civilizations, until they found an alternative source of energy and tax revenue. Rhazes’ experiments proved that it was right under their feet, but there it would stay for another thousand years.
In the meantime, oil lamps evolved. The design of a 9th-century oil lamp looks simple, but it is remarkably sophisticated. Think about a bowl of olive oil. If you simply try to light it, you’ll find it’s quite difficult. It’s hard because olive oil has a very high flashpoint. The flashpoint of a flammable liquid is the temperature at which it will spontaneously react with the oxygen in the air and burst into flames; for olive oil this is 315°C. That’s why cooking with olive oil is so safe. If you spill it in your kitchen, it’s not going to ignite.
Also, to fry most foods you only need to get to a temperature of around 200°C, which is still a hundred degrees below olive oil´s flashpoint, so it’s easy to cook without the oil burning. But at 315°C, your pot of olive oil will burst into flames, and in doing so, will create a lot of light. Not only is this incredibly dangerous, but the flames will be short-lived; they´ll consume all the fuel very quickly. Surely, you must be thinking, there’s a better way to burn olive oil for light. And as it turns out, there is. If you take a piece of string, submerge it in the oil, leaving the top poking above the surface, and then light it, a bright flame is created at the tip of the string without having to heat up the full pot of oil, It is not the string that creates the flame; it is the oil emerging from the string. This is ingenious, but it gets better. If you continue to let it burn, the flame doesn’t travel down into the oil- instead the oil climbs up the string, only igniting when it gets to the top. This system can maintain the flame for hours; indeed, for as long as there is oil in the bowl. It’s a process called wicking, and seems miraculous – the oil is able to defy gravity and move autonomously – but it’s a basic principle of liquids and it´s possible because they possess something called surface tension.
What gives liquids their ability to flow is their structure – they are an intermediate state between the chaos of gas and the static prison (for molecules) of solids. In gases, molecules have enough heat energy to break away from each other and move autonomously. This makes gases dynamic – they expand to fill the available space – but they have almost no structure. In solids the force of attraction between the atoms and molecules is much greater than the heat energy they possess, causing them to bond together. Thus solids have a lot of structure but little autonomy – when you pick up a bowl, all the atoms of that bowl come together as one object. Liquids are an intermediate state between the two. The atoms have enough heat energy to break some of the bonds with their neighbours, but not enough to break all of them and become a gas. So they are stuck in the liquid, but able to move around within it. This is what a liquid is – a form of matter in which molecules swim around, making and breaking connections to each other.
Molecules at the surface of a liquid experience a different environment from those inside the liquid. They are not completely surrounded by other molecules, so they experience less bonding on average than those in the middle of the liquid. This imbalance of forces between the surface and the interior of the liquid creates a force of tension – called surface tension. The force is tiny, but it’s still big enough to oppose the force of gravity on small things: this is why some insects are able to walk on the surface of ponds.
Look carefully at a pond skater insect as it ‘walks’ on water and you see that its legs are repelled by the water – this happens because the surface tension between the water and the insect’s legs generates a repulsive force that acts against gravity. Some liquid-solid interactions do the opposite and create a molecular force of attraction. This is true of water’ and glass. Take a glass of water and you will see the edges of the water are pulled up where they meet the glass. We call this the meniscus and it too is a surface tension effect.
Plants have mastered this same trick. They pull water up against the force of gravity, from the ground into their bodies, using a system of tiny tubes that run through their roots, stems and leaves. As the tubes become microscopic, so the ratio of the tube’s inner surface area to the volume of liquid increases, and so the effect gets bigger. Hence manufacturers sell ‘microfibre’ cloths for window cleaning, which have microchannels similar to a plant’s. They suck up water, allowing the cloth to clean more efficiently, Kitchen tissue mops up liquid spills using the same mechanism. These are all examples
of ‘wicking‘, the same surface tension effect that allows oil to climb up a string – or, more precisely, a wick.
Without wicking, candles wouldn’t work. When you light the wick on a candle, the heat melts the wax and creates a pool of molten wax. This liquid wax travels up the wick, through microchannels, to the flame. Thus feeding the flame with a new supply of liquid wax to burn. If you choose the right material for the wick, the flame will burn hot enough to maintain a pool of liquid wax, and ensure a constant flow of fuel. This deceptively complex system is self-regulating, and requires so little input from us we no longer regard candles as a piece of technology, but that is exactly what they are.
For thousands of years, all across the globe, wicking provided the primary mechanism for indoor lighting, whether in candles or oil lamps. Without these two technologies, at night the world descended into a dark gloom. As you might expect, oil lamps were popular in places where oils were plentiful, while candles were used where wax or animal fat were more readily available. Nevertheless, as ingenious as they were, candles and oil lamps had their drawbacks: there was obviously the fire risk, but there were also the production of soot, the low brightness of the flame, the smell and the cost. These shortcomings meant that there were always those searching for better and cheaper and safer ways of providing indoor light. Rhazes’ discovery of kerosene in the 9th century would have been the solution, had anyone realized it.
Comming back to my flight to New York, on board the aircraft, the pre- flight safety briefing was in full swing and now the flight attendants too were ignoring the importance of kerosene. There had not been the least mention of it so far, even though this revolutionary stuff was, at that very moment, being sprayed into the jet engines under the plane’s wings to power our aircraft as it taxied to the runway. Instead they were talking about what to do in the event of ´loss of cabin pressure’. As a native English speaker I do appreciate the understated nature of this phrase. It sounds like no big deal, but what it means is that while cruising at high altitude, if the cabin suddenly developed a hole or a crack, all the air would be sucked out of the aircraft, along with anyone not strapped into their seat. There wouldn’t be enough oxygen to breathe normally, hence the oxygen masks that are designed to drop down from the ceiling. The aircraft would immediately begin a steep descent to reach lower altitudes, where there is more oxygen. Anyone left alive at that point would indeed be safe.
Lack of oxygen was a problem for ancient oil lamps too. The design didn’t allow enough oxygen to get to the fuel to burn it fully, which is why the flame gave off relatively low light. This was a problem right up until the 18th century, when a Swiss scientist named Ami Argand invented a new type of oil lamp that used a sleeve-shaped wick protected by a transparent glass shield. It was designed so that air could pass through the middle of the flame, radically improving the amount of oxygen delivered and thus the efficiency and brightness of oil lamps, making them equivalent to 6 or 7 candles. This innovation led to many more, and eventually it became clear that olive oil and other vegetable oils were not ideal fuels. To get brighter light you need higher temperatures and for that you need faster wicking, and the speed of the wicking is determined by the surface tension and the viscosity of the liquid. Trying to find oils that were cheap but also had a low viscosity led to more experimentation, and, sadly, the deaths of a lot of whales.
Whale oil is produced by boiling strips of whale blubber. The oil the blubber releases is a clear honey colour. It’s not great for cooking or eating because of its strong fishy taste, but with a flashpoint of 230°C and low viscosity, it is very good for oil lamps. The use of whale oil in Argand lamps skyrocketed in the late 18th century, especially in Europe and North America. Between 1770 and 1775 the whalers of Massachusetts produced 45,000 barrels of whale oil per year to meet the demand. Whaling became a big industry, fuelled by the need for indoor lighting, and some whale species were almost driven to extinction by that demand. It’s estimated that by the 19th century more than a quarter of a million whales had been killed for their oil.
This could not go on, and yet the demand for indoor lighting was still on the rise. As human populations grew bigger and wealthier, education became more important, the culture of reading and entertaining after dark became more prevalent, and so the demand for oils increased, as did the pressure on inventors and scientists to come up with ways to meet this need. Among them was James Young, a Scottish chemist who, in 1848, found a way to extract a liquid out of coal that had excellent properties for burning in an oil lamp. Young called his liquid paraffine oil. A Canadian inventor, Abraham Gesner, did the same thing and called his product kerosene. These discoveries might not have come to much, but, as it turned out, they just preceded the beginning of the American Civil War.
Whaling ships became military targets, and taxes on other lamp oils created an opportunity for this new kerosene industry to find a foothold. But it didn’t really take off until inventors started playing around not with coal, but with the black oil that would be found near coal mines. This crude oil, which had to be pumped out of the ground, is a black, smelly, sticky substance. But before they could use it they had to harness distillation, an old trick first used for this by Rhazes – which proved to be extremely lucrative. Now the genie really was out of the lamp.
Meanwhile, on board my plane, there was still no word of the kerosene. The safety briefing had got to the bit about emergeney exits and the flight attendant in front of me was shooting out his arms, fingers extended to identify their location. There were 2 exits behind me, and 2 at the front of the aircraft, and 2 over the wings, I was told. I wanted to add: “and there are 50,000 litres of kerosene in the fuel tank below our feet, and another 50,000 litres stored in each of the two wings of the aircraft”.
Many people who are frequent plane travelers are telling me that I shoudn’t worry at all about flights and just relax giving me the standard expression something as follows:
“Relax. Flying is the safest form of long-distance travel- do you know that every day there are more than a million humans flying in the stratosphere – the chance of anything bad happening is minuscule. No, it’s smaller than minuscule. Sit back. Relax. Read a book.”
Yeah sure, it is the safest indeed, and as I said at the beginning of this post I enjoy flying. When I have flights in long distance such as from Europe to USA or Europe to Asia, I always have a book or 2 with me. I am totally ok with it; but everytime I look on the window or the plane goes through a turbulence zone while on the fly, even if is safest way of travelling, I do have that feeling of insecurity, no matter how much I relax myself. In the history of my travels by plane I did experience few time that drop of pressure due to some turbulence. I still remember some years ago (5 or 6), 2 times just before the landing for few seconds the turbulences were so stong that I litterally felt that the plane is falling. So sure flyong is the safest way of travelling, but when the things start to become critical there is also a minor chance to come out alive. So I would say, yes flying is the safest way of travelling but can become (even if extremelly rare) a deadly adventure too.