Mitigation of aviation's environmental impact
Encyclopedia
Aviation
Aviation is the design, development, production, operation, and use of aircraft, especially heavier-than-air aircraft. Aviation is derived from avis, the Latin word for bird.-History:...
has an impact on the environment
Environment (biophysical)
The biophysical environment is the combined modeling of the physical environment and the biological life forms within the environment, and includes all variables, parameters as well as conditions and modes inside the Earth's biosphere. The biophysical environment can be divided into two categories:...
due to aircraft engine
Aircraft engine
An aircraft engine is the component of the propulsion system for an aircraft that generates mechanical power. Aircraft engines are almost always either lightweight piston engines or gas turbines...
s emitting noise
Noise pollution
Noise pollution is excessive, displeasing human, animal or machine-created environmental noise that disrupts the activity or balance of human or animal life...
, particulates, and gases which contribute to climate change
Climate change
Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...
and global dimming
Global dimming
Global dimming is the gradual reduction in the amount of global direct irradiance at the Earth's surface that was observed for several decades after the start of systematic measurements in the 1950s. The effect varies by location, but worldwide it has been estimated to be of the order of a 4%...
. Despite emission reductions from automobiles and more fuel-efficient (and therefore less polluting) turbofan
Turbofan
The turbofan is a type of airbreathing jet engine that is widely used for aircraft propulsion. A turbofan combines two types of engines, the turbo portion which is a conventional gas turbine engine, and the fan, a propeller-like ducted fan...
and turboprop
Turboprop
A turboprop engine is a type of turbine engine which drives an aircraft propeller using a reduction gear.The gas turbine is designed specifically for this application, with almost all of its output being used to drive the propeller...
engines, the rapid growth of air travel
Air travel
Air travel is a form of travel in vehicles such as airplanes, helicopters, hot air balloons, blimps, gliders, hang gliding, parachuting or anything else that can sustain flight.-Domestic and international flights:...
in recent years contributes to an increase in total pollution attributable to aviation
Aviation
Aviation is the design, development, production, operation, and use of aircraft, especially heavier-than-air aircraft. Aviation is derived from avis, the Latin word for bird.-History:...
. In the EU
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
, greenhouse gas
Greenhouse gas
A greenhouse gas is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The primary greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
emissions from aviation increased by 87% between 1990 and 2006.
At present aviation accounts for 2% of global CO2 emissions and this is projected by the IPCC
Intergovernmental Panel on Climate Change
The Intergovernmental Panel on Climate Change is a scientific intergovernmental body which provides comprehensive assessments of current scientific, technical and socio-economic information worldwide about the risk of climate change caused by human activity, its potential environmental and...
to rise to 3% by 2050.
This presents the operators of aircraft with a responsibility to reduce emissions.
Methods of mitigating aviation’s CO2 emissions
Mitigation of aviation's environmental impact can be achieved through a variety of measures, the most obvious and arguably the most economical of which is to reduce the fuel burn of the aircraft as this accounts for 28% of an airlines costs. However there is a wide variety of other options available to minimise aviation's growing impact upon the environment as are listed below :Aircraft efficiency
The next-generation of aircraft, including the Boeing 787 Dreamliner, Airbus A350
Airbus A350
The Airbus A350 is a family of long-range, wide-body jet airliners under development by European aircraft manufacturer Airbus.A consortium originally comprising European aerospace companies from the UK, France, Spain and West Germany, Airbus is now fully owned by EADS and since 2001 has been known...
and Bombardier CSeries
Bombardier CSeries
The Bombardier CSeries is a family of narrow-body, twin-engine, medium-range jet airliners being developed by Canadian manufacturer Bombardier Aerospace. Models are the 110-seat CS100, and the 130-seat CS300...
, are 20% more fuel efficient per passenger kilometre than current generation aircraft. This is primarily achieved through more fuel-efficient engines and lighter airframes & supporting structures made of composite materials but is also achieved through more aerodynamic shapes, winglets, a "one-piece" fuselage and more advanced computer systems for optimising routes and loading of the aircraft.
Route optimization
Currently, air traffic corridors that aircraft are forced to follow place unnecessary detours on an aircraft's route forcing higher fuel burn and an increase in emissions. An improved Air Traffic Management System with more direct routes and optimized cruising altitudes would allow airlines to reduce their emissions by up to 18%.In the European Union
European Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
, a Single European Sky
Single European Sky
The Single European Sky is a European Commission initiative by which the design, management and regulation of airspace will be coordinated throughout the European Union ....
has been proposed for the last 15 years so that there are no overlapping airspace restrictions between countries in the EU and so reduce emissions. As of yet, the Single European Sky is still only a plan but progress has been made. If the Single European Sky had been created 15 years ago, 12 million tons of CO2 could have been saved.
Biofuels
Biofuels are fuels derived from biomassBiomass
Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....
material such as plants and waste. Plant derived biofuels offer large savings in CO2 emissions as they absorb Carbon Dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
and release it as Oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
when they grow and so in a life-cycle, emissions can be drastically reduced. A number of airlines have operated biofuel test flights including Virgin Atlantic Airways
Virgin Atlantic Airways
Virgin Atlantic Airways Limited is a British airline owned by Sir Richard Branson's Virgin Group and Singapore Airlines...
, which flew with one engine operating on a blend of 20% coconut oil and 80% traditional jet fuel, and Continental Airlines
Continental Airlines
Continental Airlines was a major American airline now merged with United Airlines. On May 3, 2010, Continental Airlines, Inc. and UAL, Inc. announced a merger via a stock swap, and on October 1, 2010, the merger closed and UAL changed its name to United Continental Holdings, Inc...
which flew with one engine operating on a blend of 44% Jatropha
Jatropha
Jatropha is a genus of approximately 175 succulent plants, shrubs and trees , from the family Euphorbiaceae. The name is derived from the Greek words ἰατρός , meaning "physician," and τροφή , meaning "nutrition," hence the common name physic nut. Mature plants produce separate male and female...
oil, 6% Algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...
oil and 50% traditional jet fuel. Other airlines to demonstrate biofuels include Air New Zealand
Air New Zealand
Air New Zealand Limited is the national airline and flag carrier of New Zealand. Based in Auckland, New Zealand, the airline operates scheduled passenger flights to 26 domestic destinations and 24 international destinations in 15 countries across Asia, Europe, North America and Oceania, and is...
and Japan Airlines
Japan Airlines
is an airline headquartered in Shinagawa, Tokyo, Japan. It is the flag carrier of Japan and its main hubs are Tokyo's Narita International Airport and Tokyo International Airport , as well as Nagoya's Chūbu Centrair International Airport and Osaka's Kansai International Airport...
.
In the Continental Airlines test, the engine running partly on biofuel burned 46 kg less fuel than the conventionally fuelled engine in 1 and a half hours while producing more thrust from the same volume of fuel. Continental Airlines' CEO, Larry Kellner, commented "This is a good step forward, an opportunity to really make a difference to the environment" citing jatropha's 50-80% lower CO2 emissions as opposed to Jet-A1 in its lifecycle.
From 2014 onwards, British Airways
British Airways
British Airways is the flag carrier airline of the United Kingdom, based in Waterside, near its main hub at London Heathrow Airport. British Airways is the largest airline in the UK based on fleet size, international flights and international destinations...
, in co-operation with Solena, is going to turn half a million tonnes of waste annually that would normally go to landfill
Landfill
A landfill site , is a site for the disposal of waste materials by burial and is the oldest form of waste treatment...
from the City of London
City of London
The City of London is a small area within Greater London, England. It is the historic core of London around which the modern conurbation grew and has held city status since time immemorial. The City’s boundaries have remained almost unchanged since the Middle Ages, and it is now only a tiny part of...
into biofuel to be used in the British Airways fleet. Waste derived biofuel produces up to 95% less pollution in its life-cycle and so therefore this measure will reduce emissions by the equivalent of taking 42,000 cars off the road every year.
Improved operating procedures
Continuous Descent Approach
Continuous Descent Approach or Optimized Profile Descent is a method by which aircraft approach airports prior to landing. It is designed to reduce fuel consumption and noise compared to certain conventional approaches and involves maintaining a constant three degree descent angle during landing,...
, or CDA, which can reduce emissions significantly during the operations in and around an airport. Scandinavian Airlines (SAS) is now operating its Boeing 737
Boeing 737
The Boeing 737 is a short- to medium-range, twin-engine narrow-body jet airliner. Originally developed as a shorter, lower-cost twin-engine airliner derived from Boeing's 707 and 727, the 737 has developed into a family of nine passenger models with a capacity of 85 to 215 passengers...
fleet at a slower cruising speed to help reduce emissions by 7-8%.
Emission Trading Scheme
In the EUEuropean Union
The European Union is an economic and political union of 27 independent member states which are located primarily in Europe. The EU traces its origins from the European Coal and Steel Community and the European Economic Community , formed by six countries in 1958...
, aviation will be including the European Emission Trading Scheme
European Union Emission Trading Scheme
The European Union Emissions Trading Scheme also known as the European Union Emissions Trading System, was the first large emissions trading scheme in the world. It was launched in 2005 to combat climate change and is a major pillar of EU climate policy...
from 2012 onwards. The scheme places a cap on the emissions an aircraft operator can emit and forces the operator to either lower emissions through more efficient technology or to buy "Carbon Credits" from other companies who have produced fewer emissions than their cap. It is thought that this will reduce aviation's net environmental impact.
Methods of mitigating aviation’s non-CO 2 emissions
Aviation produces a number of other pollutants besides carbon dioxide including nitrogen oxideNitrogen oxide
Nitrogen oxide can refer to a binary compound of oxygen and nitrogen, or a mixture of such compounds:* Nitric oxide, also known as nitrogen monoxide, , nitrogen oxide* Nitrogen dioxide , nitrogen oxide...
s (NOX), particulates
Particulates
Particulates – also known as particulate matter , suspended particulate matter , fine particles, and soot – are tiny subdivisions of solid matter suspended in a gas or liquid. In contrast, aerosol refers to particles and/or liquid droplets and the gas together. Sources of particulate matter can be...
, unburned hydrocarbon
Unburned hydrocarbon
Unburned hydrocarbons are the hydrocarbons emitted after petroleum is burned in an engine.Any fuel entering a flame will be reacted. Thus, when unburned fuel is emitted from a combustor, the emission is caused by fuel "avoiding" the flame zones...
s (UHC) and contrail
Contrail
Contrails or vapour trails are artificial clouds that are the visible trails of condensed water vapour made by the exhaust of aircraft engines...
s. A number of methods to reduce the level of these pollutants follows:
Nitrogen oxides (NOX)
Nitrogen oxides have a far stronger impact upon climate change than Carbon Oxides and are produced in small quantities from aircraft engines. Engine designers have worked since the start of the jet ageJet age
The Jet Age is a period of history defined by the social change brought about by the advent of large aircraft powered by turbine engines. These aircraft are able to fly much higher, faster, and farther than older piston-powered propliners, making transcontinental and inter-continental travel...
to reduce NOX emissions and the result is ever reducing levels of nitrogen oxide emissions. For example, between 1997 and 2003, NOX emissions from jet engines fell by over 40%.
Particulates
Particulates and smoke were a problem with early jet engines at high power settings but modern engines are designed so that no smoke is produced at any point in the flight.Unburned hydrocarbons (UHC)
Contrails
Aircraft flying at high altitude form condensation trails or contrails in the exhaust plume of their engines. While in the TroposphereTroposphere
The troposphere is the lowest portion of Earth's atmosphere. It contains approximately 80% of the atmosphere's mass and 99% of its water vapor and aerosols....
these have very little climatic impact. However, jet aircraft cruising in the Stratosphere
Stratosphere
The stratosphere is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. It is stratified in temperature, with warmer layers higher up and cooler layers farther down. This is in contrast to the troposphere near the Earth's surface, which is cooler...
do create an impact from their contrails, although the extent of the damage to the environment is as yet unknown. Contrails can also trigger the formation of high-altitude Cirrus cloud
Cirrus cloud
Cirrus clouds are atmospheric clouds generally characterized by thin, wispy strands, giving them their name from the Latin word cirrus meaning a ringlet or curling lock of hair...
thus creating a greater climatic effect.
In the three days following the September 11 Attacks on the World Trade Center
World Trade Center
The original World Trade Center was a complex with seven buildings featuring landmark twin towers in Lower Manhattan, New York City, United States. The complex opened on April 4, 1973, and was destroyed in 2001 during the September 11 attacks. The site is currently being rebuilt with five new...
in New York City
New York City
New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...
, when no commercial aircraft flew in the USA, climate scientists measured the daily temperature range over 5000 weather stations across the USA. The results showed a 1 ° Celsius change in the average daily temperature range for those days of the year, thus showing contrails do have a significant impact on climate. Potential ways of reducing the impact of contrails on our climate include reducing the maximum cruising altitude of aircraft so high-altitude contrails can not form. Cruising at lower altitudes would marginally increase flight time and increase fuel consumption by 4%.
Methods of mitigating aviation's noise emissions
One of the by-products of an aircraft's engine is noise and this has become an increasingly important issue which is being dealt with through many different methods:Engines
Next-Generation engines are not only more fuel-efficient but also tend to be quieter with Pratt & WhitneyPratt & Whitney
Pratt & Whitney is a U.S.-based aerospace manufacturer with global service operations. It is a subsidiary of United Technologies Corporation . Pratt & Whitney's aircraft engines are widely used in both civil aviation and military aviation. Its headquarters are in East Hartford, Connecticut, USA...
's PurePower PW1000G fitted to the Bombardier CSeries
Bombardier CSeries
The Bombardier CSeries is a family of narrow-body, twin-engine, medium-range jet airliners being developed by Canadian manufacturer Bombardier Aerospace. Models are the 110-seat CS100, and the 130-seat CS300...
aircraft being 4 times quieter than aircraft currently in service. Engines can also incorporate serrated edges on the back of the nacelle
Nacelle
The nacelle is a cover housing that holds engines, fuel, or equipment on an aircraft. In some cases—for instance in the typical "Farman" type "pusher" aircraft, or the World War II-era P-38 Lightning—an aircraft's cockpit may also be housed in a nacelle, which essentially fills the...
to reduce noise impact as shown in this picture.
Improved operating procedures
A Continuous Descent ApproachContinuous Descent Approach
Continuous Descent Approach or Optimized Profile Descent is a method by which aircraft approach airports prior to landing. It is designed to reduce fuel consumption and noise compared to certain conventional approaches and involves maintaining a constant three degree descent angle during landing,...
, or CDA, not only reduces fuel burn but also allows airlines to provide quieter approaches for part of the descent to a runway. As the engines are at close to idle power, less noise emissions are produced and combined with new engine technology, the reductions in noise emissions can be large.
Carbon offset
A carbon offsetCarbon offset
A carbon offset is a reduction in emissions of carbon dioxide or greenhouse gases made in order to compensate for or to offset an emission made elsewhere....
is a means of reducing emissions to zero by saving enough carbon to balance the carbon emitted by a particular action. Several airlines have begun offering carbon offsets to passengers to offset the emissions created by their proportion of the flight. Money generated is put to projects around the world to invest in green technology such as renewable energy and research into future technology. Airlines offering carbon offsets include British Airways
British Airways
British Airways is the flag carrier airline of the United Kingdom, based in Waterside, near its main hub at London Heathrow Airport. British Airways is the largest airline in the UK based on fleet size, international flights and international destinations...
, easyJet
EasyJet
EasyJet Airline Company Limited is a British airline headquartered at London Luton Airport. It carries more passengers than any other United Kingdom-based airline, operating domestic and international scheduled services on 500 routes between 118 European, North African, and West Asian airports...
, Continental Airlines
Continental Airlines
Continental Airlines was a major American airline now merged with United Airlines. On May 3, 2010, Continental Airlines, Inc. and UAL, Inc. announced a merger via a stock swap, and on October 1, 2010, the merger closed and UAL changed its name to United Continental Holdings, Inc...
, Delta Air Lines
Delta Air Lines
Delta Air Lines, Inc. is a major airline based in the United States and headquartered in Atlanta, Georgia. The airline operates an extensive domestic and international network serving all continents except Antarctica. Delta and its subsidiaries operate over 4,000 flights every day...
, Lufthansa
Lufthansa
Deutsche Lufthansa AG is the flag carrier of Germany and the largest airline in Europe in terms of overall passengers carried. The name of the company is derived from Luft , and Hansa .The airline is the world's fourth-largest airline in terms of overall passengers carried, operating...
and Qantas
Qantas
Qantas Airways Limited is the flag carrier of Australia. The name was originally "QANTAS", an initialism for "Queensland and Northern Territory Aerial Services". Nicknamed "The Flying Kangaroo", the airline is based in Sydney, with its main hub at Sydney Airport...
although there are many more carriers participating in such schemes.
British Airways' scheme
British Airways' carbon offsetting scheme involves paying a fee dependant on aircraft type, class of travel and distance flown and therefore prices vary. Funds generated are currently awarded to three renewable energy projects around the world: Bayin'aobao wind farm in Inner MongoliaMongolia
Mongolia is a landlocked country in East and Central Asia. It is bordered by Russia to the north and China to the south, east and west. Although Mongolia does not share a border with Kazakhstan, its western-most point is only from Kazakhstan's eastern tip. Ulan Bator, the capital and largest...
, Faxinal dos Guedes hydroelectric power plant in Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
and Xiaohe hydroelctric power plant in Gansu Province, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
.
Continental Airlines' scheme
Continental Airlines' carbon offsetting scheme involves paying a fixed fee of $2 to cancel out emissions through reforestation. Passengers can also choose to pay $50 for offsetting emissions through renewable energy projects.See also
- Air transport and the environment (United Kingdom)Air transport and the environment (United Kingdom)The environmental impact of aviation in the United Kingdom is increasing due to the increasing demand for air travel in the country. In the past 25 years the UK air transport industry has seen sustained growth, and the demand for passenger air travel in particular is forecast to increase more than...
- Environmental impact of aviation
- HypermobilityHypermobility (travel)The term hypermobility in regard to travelers arose around 1980 and is a concept that has increased in useage since the early 1990s: Damette ; Hepworth and Ducatel ; Whitelegg ; Lowe ; van der Stoep ; Shields ; Cox ; Adams ; Khisty and Zeitler ; Gössling et al. ; and Mander & Randles...