Mario Buildreps is a graduate engineer. Become aware of topics in a way you have never heard before.
Flying in 2014
Flying became a way to travel to the other side of the globe in about one day. Flying is preferred above travelling by car or train, because it goes fast and straight.
The flight industry accounts for 2.2% of the global economy (2.4 trillion$ vs. 108 trillion$ in 2014)
2014 is the first year in history with more than 100,000 scheduled flights per day, covering globally nearly 50,000 routes. According to year reports, air travel would be responsible for 2% of the world's emitted carbon dioxide. This figure seems to have clear relations with its economical share.
Average Flight Distances and Time
|World||2400 km (1491 mi)||Flight time: 168 min|
2300 km (1429 mi)
Flight time: 162 min
2270 km (1410 mi)
Flight time: 160 min
At What Altitude Fly Airplanes?
The Turbo Fan Jet Engine
The world's first jet engine to fly solely on jet power was the Heinkel He 178, in 1939. After WWII the jet engine literally made lift-off in both military and civil airplanes.
Jet engines offer higher speeds and greater fuel efficiency than piston and propeller aeroengines. Most of the jet engines are the so called airbreathing jet engine types, that are propelled by a jet of hot exhaust gases formed from air that is drawn into the engine via an inlet duct. This engine literally breaths air (and oxygen) in, and burns it all to CO2 and complex NOx compounds.
The exhaust gases of jet engines are not suitable anymore for respiration, and has to be treated by mother Earth into oxygen again. But this takes a while though.
The jet engine made the airplanes more reliable, faster and cheaper to operate, which made the industry booming. The aviation industry growth showed since WWII an average annual growth of around 7%.
The table below shows that especially between 2009 and 2013 the amount of passengers grew with an average of 225 million passengers per year!
According to the Air Transport Action Group (ATAG), the new Airbus A380, the Boeing 787, the ATR-600 and the Bombardier CSeries aircrafts, would use less than 3 litres of jet fuel per 100 passenger kilometres. This would match the efficiency of most modern compact cars.
But this are tricky figures, because a car doesn't drive as far as an airplane. With airplanes everything goes in large numbers and are therefore also very pollutive.
A nation that destroys its soils destroys itself. Forests are the lungs of our land, purifying the air and giving fresh strength to our people.
— Franklin D. Roosevelt
Growth of Amount of Passengers
Four-engined Boeing 747
10 Most Built Commercial Airliners
Boeing 737 series
Airbus A320 series
Bombardier CRJ series
McDonnell Douglas MD-80
De Havilland Canada DHC-8
These are the most used airplanes in the air transport industry. The total amount of large airplanes in use is estimated around 35,000. So, the top 10 above represents about 65% of all large commercial airplanes in use today.
How Does a Jet Engine Work?
The Average Turbo Fan Engine
The CFM56-series turbo fan is one of the most used engines in airplanes, and is regarded as the most successful jet engine in commercial aviation history. More than 50% of the airplanes in service today are powered with this engine. The engine is mounted on the Boeing 737 series and Airbus A320 series. The engine is powerful, compact and relatively economical when compared to most other engine types.
This engine can be regarded as a standard in the modern aviation industry and will be taken as an example for the calculations below.
Spec's of a Boeing 737 With a CFM56 engine
Resulting propulsive power
Unused kinetic energy
Maximum thrust (sea level)
Thrust at cruise height (30,000 ft)
5.3 : 1
Fuel consumption: Take off
3,000 lbs / 15 min
5,500 lbs / hour
600 lbs / 20 min
2,500 lbs / 30 min
2,000 lbs / 20 min
Fuel and Air Consumption of a Modern Turbo Fan Engine
One of the most typical design features of a modern (quiet) turbofan engine is a high bypass ratio. The bypassed air goes through the outer part of the engine, and is not directly involved in the combustion process. The cold air forms a sound insulating shield around the burning gases that come from the noisy engine core. This ratio lies mostly between 5:1 up to 6:1 (most air runs via the bypass).
After leaving the engine, the cold air will mix with the exhaust fumes, whereby another postreaction occurs, which leads to a large number of other complex poisonous compounds like NOx, HNOy, SOx and H2SO4.
Most modern turbo fan engines have a bypass ratio of 5:1. 5 kg (11 lbs) passes the engine, while 1 kg (2.2 lbs) of air is used in the actual combustion process.
An average airliner with two engines like the CFM56 types has the following specifications:
- ratio fuel/air = 0.02871 at cruise height of 30,000 feet,
- average fuel consumption during 2.8 hour flight = 20,475 lbs2,
- average CO2 production per average flight = 63,985 lbs3.
Air Densities of the Atmosphere
|Altitude in feet||Air pressure hPa||Density kg/m3||Temperature °C|
Pollution of 100,000 Scheduled Flights Per Day
At cruise altitude of around 30,000 feet the density of air is 33% of the density at sea level (density and pressure are not proportional). To develop enough thrust power at cruise altitude this airflow has to be 3 times as high as on sea level.
The bypass ratio of 5.3:1 however plays also a major role. The exhaust gases mix with the bypassed air and form complex compounds, like NOx, HNOy, SOx, HxSOy, soot and metal particles. There is though no additional carbon dioxide formed, this happened directly in the engines itself.
The air consumption of an average airplane like the Boeing 737, during one average flight of 2.8 hours, is 3,781,094 lbs4. This equals 1,361,194 m3 (4,809,646 ft3) at sea level.
With 100,000 scheduled flights each day, the daily amount of spoiled air is 1.4×1011 m3, thus an annual amount of 5.0×1013 m3. This annual exhausted amount of air is totally unsuitable for respiration, and is moreover very poisonous.
The Amount of Pollution Each Year
Earth's total surface is 5×108 km2 (2×108 mi2). The amount of air on Earth is estimated to be around 4.2×109 km3, and weighs together 5.1×1015 metric tonnes.
The airplane industry creates each year 5.0 ×104 km3 (12,013 mi3) of totally spoiled air. For your imagination: This equals Earth's whole surface, covered with a 4 inch thick layer of absolutely unbreathable air. And this is just 2% of all polluters!
Due to the airplane industry each year 0.00119% of Earth's atmosphere becomes unavailable to breathe, and is, moreover, poisoned. And if it's true that the airplane industry would be just 2% of the polluters, that would make each year 0.0595% of all the air unavailable to breathe.
0.00119% might seem not so much to you. But this is each year an area of 5.952 km2 (2298 mi2) where the atmosphere is spoiled from ground up to 16 km (10 mi) high. This is significantly larger as the state of Delaware.
0.0595% pollution of Earth's atmosphere is an area proportional to the state of Maryland, from sea level up to 10 miles high. Not one drop of oxygen left, and full of poisonous gases. Each year.
Source of All Life - Oxygen and Carbon Dioxide
Peeing in a swimming pool is done because people tend to believe no one notices this, and that the pee is nothing compared to the volume of the swimming pool itself. But in a very crowdy swimming pool, when all recreants like to pee in the pool too, it becomes another matter. And now imagine you have to drink daily from this pool! Let's have a look at the filtration system.
For the many among us who still don't seem to understand this:
- humans and animals breath air (oxygen),
- trees and plants breath CO2 during their lifetime.
What about all the factories, power plants, ships, trucks, cars, mopeds, scooters, gas heaters, fireplaces, barbecues, lawn mowers, leaf blowers, etc, etc?
In 2014 the global aircraft fleet:
- produced 1.05×1012 kg (2.33×1012 lbs) of CO2
- consumed 7.6×1011 kg (1.7×1012 lbs) oxygen
The total annual CO2 production for 2014 is estimated at 4.0×1013 kg. This shows that air traffic is indeed for 2% (±25%) responsible for all pollution.
Trees and Oceans
The pollution due to air traffic and all other polluters was in 2014, 0.0595% of Earth's atmosphere. This part of the atmosphere contains no oxygen anymore, and has to be compensated by trees and the oceans.
About half of the world's produced oxygen comes from trees and other green life, and the other half from the oceans (mainly by the phytoplankton's photosyn-thesis). The same balance counts for the absorption capacity of carbon dioxide.
It is an illusion to think that trees absorb carbon for eternity. Every year when a tree drops its leafs this process takes oxygen and produces CO2. When a tree finally dies the decay process uses oxygen and produces again CO2. Part of the stored carbon in a dead tree will be released again into the atmosphere. But during its lifetime an average tree stores an annual amount of about 20 kg of carbon.
How Much Can Trees Compensate?
An average tree has a net oxygen supply of about 20 kg (weight equals carbon) per year. A human being consumes about 500 kg (net) of oxygen per year. It takes 25 average trees to sustain a human being. NASA recently estimated the amount of (forested) trees at 400 billion spread over an area of 40 million km2 (15.5 million mi2) of forest.
To sustain the current aircraft activity requires 52.5 billion trees for extracting the carbon, and about 38 billion trees to recuperate the lost oxygen. The carbon production is critical. That's 13.1% of all the forest trees, and 6.5% of Earth's whole capacity.
Every year an new area of forest should be planted of about 4,500 km2. That's about replanting the size of the state of Delaware, not with seedlings, but with full grown trees! Only for the 2% air traffic.
So, compensating air travelling is not as easy as it seems. What is the business actually compensating? And where is the 'compensated' money actually going to?
If the figure is correct, that air traffic accounts for just 2% of all pollution, the magnitude of the global problem becomes visible.
- ±350% shortage in carbon dioxide storage capacity.
- ±240% shortage in oxygen production capacity.
You could possibly here and there haggle over some of the figures, but the magnitude of the problem is clear - the problem exceeded clearly 100% of Earth's capacity.
It is acknowledged by most experts that the air traffic industry is accountable for 2% of the emissions. If this is correct, that means that the scale of the emission problem is 50 times larger.
The current carbon and oxygen balance is seriously disturbed with respectively 350% and 240%. And that figure includes the capacity of the oceans!
The only way to restore the balance is to reduce emissions to below 100% and that means reducing everything with a ratio of 3.5 times. To imagine this in a simple way: 3.5 times less car activity, and 3.5 times less air traffic, etcetera.
With regard to the other compounds like NOx, HNOy, SOx, HxSOy, soot and metal particles, that's obviously an additional problem, without prospect of a solution. These highly toxic compounds that are heavier than air, come down to Earth as gases and particulates. They cause a long list of diseases, and are directly linked to 3.7 million deaths each year and increases each year (source: WHO). What to do with these megatons of toxic gases?
When economy, vacations, hurry, technological progress and comfort are preferred over environment, the Earth's atmosphere is doomed, and much sooner than anyone thinks. We passed the Point of no Return around 1960, and that's already many decades ago.
© 2015 by Buildreps
1 According to study of University of Toronto Institute for Aerospace Studies to CFM56-type engines
2 fuel consumption = take off (15 min) + cruise (average 2.25 hours) + descent (20 min) + hold + alternate
3 1 lbs kerosene produces 3.125 lbs of CO2
4total fuel consumption divided by the fuel/air ratio, multiplied with the bypass ratio of 5.3
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
Buildreps (author) from Europe on June 12, 2015:
Thanks Larry. You've said that absolutely right!
Larry Rankin from Oklahoma on June 12, 2015:
Very interesting. We must find a way to get people to care.
Buildreps (author) from Europe on June 10, 2015:
Thanks Nadine, I'm happy to hear that. We MUST plant trees, as much as possible, as big as possible!
Nadine May from Cape Town, Western Cape, South Africa on June 10, 2015:
Your hub was truly an education for me. Gosh we all MUST plant trees! I will share this hub with the text Why we all MUST plant Trees! Many thanks.
Buildreps (author) from Europe on June 01, 2015:
Thanks for your comment, Bill. The point seems to be that people do care, but this information is simply not available. It's quite a sad thing to see that indeed the point of no return is passed. The current level of emissions has risen above what nature is capable to take, and this point was already a few decades ago.
Bill Holland from Olympia, WA on June 01, 2015:
A fascinating read. A terrifying read. A cold splash of water in the face read....do people not know or do they not care? I guess it's a moot point since we've passed the point of no return but still, I would love to see more people caring about the environment.