Airplane pollution - not just hot air!
Sure, airplanes are not the most polluting vehicles on earth in the aggregate. But if you are a frequent air traveler, this is no reason for you not to feel guilty about using these birds often. And here’s why.
Have you seen your local gas station being set on fire and then flown over your head? No? Unknown to yourself, you might have seen it. No kidding. The air pollution levels from one Boeing 747 takeoff is similar to that of a gas station being set on fire.
Just to say the same story differently: the pollution from just a two-minute 747 takeoff is equal to operating 2 million lawnmowers simultaneously.
While aircraft pollution might not be such a big deal today in aggregate (only about 3% of the total environmental pollution is owing to aircraft), in specific locations such as in the vicinities of airports, the share of aircraft pollution is significantly higher. Consider this: During take off and landing the huge emissions from aircraft can spread to an area of 10 miles around the airport.
Apart from emissions, there are other avenues as well through which aircraft affect our environment and ecology directly and indirectly.
Though energy efficiency, environment awareness and pollution control have been on the radars of aircraft and aviation engineers for quite a while now, their success in making airplanes green had always been debatable.
The recent high-profile Virgin Atlantic “biofuel flight” between London and Amsterdam might have made a number of eco-aware folks happy. The famous British virgin Richard Branson proudly claimed that this flight opened a new chapter in the airline industry. But opinion is divided. Was this event just a lot of hype, or are our airplanes really becoming green?
This article investigates.
Polluting Emissions
No, this is not an aircraft on fire. This is just an aircraft firing up!
From its current contribution of less than 3%, aircraft pollution is set to grow so rapidly that all homeowners, car drivers and businesses will have to reduce their carbon dioxide output to zero for levels to remain safe, a recent UK study warned. The study says that even if the growth in air travel were halved, the rest of the economy would need to cut greenhouse gas emissions far beyond the UK government's target of 60% by 2050.
One of the biggest environmental issues with jet airliners is the nitrogen oxide emissions (NOx ) spewed into the atmosphere during takeoff and landing procedures. The emission of NOx at cruise altitudes may promote enhanced greenhouse effect, photochemical smog formation, and also depletion of the stratospheric ozone layer. But it is not just NOx. The emissions from air traffic can change the atmospheric composition – (a) Directly: by emitting CO2, water vapour, unburnt hydrocarbons, soot, sulfate particles and of course NOx, and (b) Indirectly: by chemical reactions that contribute to ozone formation.
The goal for most airlines is to reduce NOx emissions during landing and takeoff to 70 percent below the international standards created in 1996. While experts admit that we're not there yet, some feel that airlines are making good progress.
Aircraft also emit the notorious global warming villain CO2. Like most others in the transportation industry, the aircraft industry has been talking smooth about and making plans for reducing CO2 emissions. EasyJet for instance last year unveiled the prototype for an aircraft that could slash carbon dioxide emissions by half. But most of these have remained just at the planning and prototype stages.
In sum, their grand pronouncements and prototypes aside, not too many are convinced that airlines have done enough to reduce NOx and CO2 emissions.
Grade for Emission Control: B-
Alternative Fuel & Fuel Efficiency
Virgin Atlantic biofuel flight. Hot stuff or just hot air?
Alt Fuel
Fuel is the second largest cost component for airlines (first is of course the cost of folks running the airline and the aircraft).
Aircraft burn tremendous amounts of fuel, sometimes in excess of a hundred tons on a single round trip. A Boeing 707, for example, consumes on the average 12300 pounds (about 5600 Kg) of fuel per hour.
Almost all of the fuel airplanes use today are fossil fuel. Is this likely to change? There are at least some efforts to make this change happen.
Airplane makers are investing heavily into alternative energy fuels. Some in the airline industry feel that coal-to-oil (using the Fischer-Tropsch process) is possibly the most workable near-term alternative, but this is still fossil fuel.
Boeing is trying its hand at using biofuels derived from feedstock such as algae. Boeing researchers have also conducted experimental flight tests of manned airplanes powered only by fuel cells and lightweight batteries ( more here ). Richard Branson of Virgin Atlantic has been talking big about biofuel powered Virgin flights, and his company actually flew one last week.
This first flight by a biofuel powered commercial airline took place on 24 Feb 2008, amindst much fanfare, when a Virgin Atlantic jumbo jet flew between London's Heathrow and Amsterdam using fuel derived from a mixture of Brazilian babassu nuts and coconuts. Earlier this month, Airbus tested a synthetic mix of gas-to-liquid.
If these news make you look forward to travelling on a biofuel powered airplane anytime soon, you will be disappointed. Most of these alt energy / fuel efforts have really been a lot of show. All research work being carried out are in their very initial stages. (by the way, here’s a nice Q&A on alt fuels in airplanes, from Airlines.org)
Grade for Alternative Energy Use: B-
Fuel Efficiency
Airlines' record in fuel efficiency is not exactly bad – a 103 percent improvement between 1978 and today. Fuel efficient aircraft designs and less-fuel-guzzling aircraft engines have been on the radars of the aircraft engineers for many years now, and some of their earlier research has started to bear fruit.
Boeing in 2007 launched what it says is the most environmentally-friendly aircraft ever built. The Boeing 787 achieves fuel efficiency by having a significant percentage of aircraft made from composites, making it lighter and more fuel efficient than traditional aircraft. While environmental groups say the aircraft is far from green, some do admit that its lighter weight will enable it to use 20 per cent less fuel than its aluminium predecessors.
In Nov 2007, Boeing said it was developing a new single-aisle aircraft made of composite materials to replace the 737, its most popular aircraft ever. According to the planemaker, the 737-RS would also incorporate new engine types that achieve greater fuel efficiency. The advanced materials, comprising ceramic matrix composites and such, also allow engines to burn at higher temperatures. When engines operate at these high temperatures, they are more efficient. Other lightweight materials like Titanium Aluminide and other superalloys are also being researched for potential engine material.
Relatively speaking, the airlines have done reasonably well in their efforts for fuel efficiency.
Grade for Fuel Efficiency: A-
Noise Pollution
Would you like to live in this house?
Aircraft noise continues to be a nuisance.
And not just a nuisance. Thousands of people are possibly killed each year by increases in blood pressure triggered by night-time noise from aircraft, a new study claims. Researchers found the sound of planes taking off and landing while people sleep increases blood pressure, and those living closest to airports were almost 50 per cent more likely to suffer from hypertension..
So what are airlines and aircraft companies doing about this?
Thanks to technology, today's aircraft are 50% quieter than those 10 years ago. Research initiatives target a further 50% reduction by 2020, according to IATA. Further, in January 2006, a more stringent noise certification standard was introduced by IATA for new aircraft designs. These aircraft should be at least one third quieter than those currently certified.
Specific efforts have been underway in reducing the noise from two main components – engines and the airframe, especially the engine.
Much of the noise from gas turbine engines comes from air flowing back through the rapidly spinning fan blades at the front of the engine. Behind each blade is a wake, or an area of lower-speed air. When these wakes move over stationary blades they produce strong, unsteady pressures, and consequently most of the sound.
Most noise-control measures, such as acoustic liners in the engines, had traditionally focused on reducing the amplitude of the sound after it is produced, and these have had only limited success. But scientists are now working on a method of cutting down on noise at the source. Their idea is to "fill in" the wake behind each rotor blade by pushing air through the trailing edges of the rotating blades, where it mixes with the air flowing around the blade and makes the flow into the stator more uniform.
Another recent approach to noise reduction is the active noise control effort. The primary principle of active noise control is to sense the noise disturbances in the engine and cancel them before they leave the engine. In effect, negative noise is made to cancel out the engine's sound waves so that no noise is heard.
On noise control, one wishes to give the airlines and aircraft industry a good grade for all their efforts, but until our friends and folks living near airports are able to have a good night's sleep in their houses near airports, we have no choice but to give it a rather mediocre grade.
Grade for Noise Control: B
Plane Deicing
Makes the "birds" healthier, but what about humans?
De-icing is the process of removing ice from an airplane's surface.
The chemicals normally used to deice aircraft - ethylene glycol and propylene glycol – are both deadly substances even in small quantities. Ethylene glycol causes central nervous depression and kidney and liver damage and propylene glycol is just as toxic. While no studies have been done on its effects on humans, each winter large amounts of fish and wildlife are poisoned to death by aircraft deicing chemicals.
Additional pollutants, including fuels and other toxic substances, are also washed off the planes during deicing procedures.
Compared to the rest of components of aircraft pollution, this is a minor one, though it could have harmful effects on those few who perform this activity, and on some unfortunate fish and fowl. This aspect of aircraft pollution has not received much attention so far.
Grade for Deicing Pollution Control: B
Not There Yet, But Hopeful
Attaboy! You've painted it green, now can you make it green?
As things stand today, while aircraft manufacturers and the aviation industry have been taking measures to make the birds more environment-friendly, these have only had a limited impact. But with aircraft manufacturers and the aviation industry making all-out efforts at convincing the world that they are “green”, we might be able to see some significant technologies and measures being put in place to give the eco-aware airplane traveler a less guilty feeling.
Overall Grade for being Green: B
So don’t count on your next aircraft being green, but you will probably be justified if you don’t see red.
