Commercial Aviation Emissions and Global Surface Temperatures by Jerome Lawrence McNair Scholars Program Embry-Riddle Aeronautical University
Purpose The purpose of this research is to analyze the amounts and effects of various emissions from commercial aviation, determine which gases contribute to warming or cooling the atmosphere,and estimate the average net radiative forcing (W/m2) forecast for 2050.
Introduction • Aviation: Very important role in the diversity and prosperity of a country’s economy• Presently: Air transport industry provides 28 million direct, indirect and induced jobs worldwide• Compared with total passenger kilometers flown in 1995, an estimated increase of between 450% to 820% by 2050• This growth will result in 14 billion to 23 billion passenger kilometers flown annually by mid-century
Radiative Forcing • Radiative forcing (RF) is a concept used for quantitative comparisons of the strength of different human and natural agents in causing climate change. • Each agent has a different RF value.• CO2 concentrations in 2005 had an RF of 1.66 [±0.17] Wm-2: a 20% increase from 1995.
Components of the Climate Change Process (IPCC, 2007)
Hypothesis It is hypothesized thatthe projected increase in air travel (pass. km) will significantly increase the positive radiative forcing (W/m2) from commercial aviation emissions
Combustion Process• CO2, NOx, SOx, H2O and soot are all by products of combustion• For every gallon of fuel burned,21 lbs of CO2 is emitted • Reducing fuel use reduces the amount of CO2 emitted (GAO, 2009)
Air Quality and Aircraft Emissions Volatile Organic Compounds•VOCs: Umbrella term for numerous compounds thatbecome a gas at normal pressures and temperatures •Extended exposure to some VOCs results in: eye and respiratory tract irritation, visual problems, headaches, dizziness, and memory impairment
Air Quality and Aircraft Emissions Unburned hydrocarbons •During the combustion process, some of thesehydrocarbons are not burned completely or not burned at all and are referred to as Unburned Hydrocarbons •The top of nitrogen oxides and VOCs are • 1.chemical factories 2. oil refineries 3.power stations 4.airports
The • As the sun’s energy traverses theGreenhouse atmosphere it does not change theEffect temperature of the atmosphere, but it changes the temperature of the land. • Earth then reradiates a longer wave of energy that falls in the thermal infrared band of wavelengths of the electromagnetic spectrum. • These wavelengths are easily absorbed by greenhouse gases, such as carbon dioxide, water vapor, methane, and ozone
Air Quality and Aircraft Emissions Nitrogen oxides•Nitrogen oxides (NOx) include nitrogen dioxide (NO2), nitric oxide (NO), and nitrous oxide (N2O).•Estimates for specific engine-airframe combinations range from 6 to 40g of NOx per kilogram of fuel burned•The World Wildlife Federation estimated that NOx emitted from aircraft above 10,000 feet have up to 50 times the warming effect of NOx emitted at lower levels.
Air Quality and Aircraft Emissions Particulate matter •Particulate matter is a subset of the larger group known as aerosols•Many particulates, such as soot, serve as condensation nuclei for water vapor in the atmosphere and tend to form more high cirrus clouds than would otherwise be present.
Air Quality Carbon dioxideand Aircraft •Preindustrial levels of CO2 were 280Emissions ppm and the global average for 2011 was 392 ppm. •Nearly 20% of the greenhouse gas emissions worldwide are from transportation. •The CO2 emitted by air transport is at least 0.23 billion tonnes of carbon dioxide (GtC) per year. • By 2050, aviation is expected to add 1.45 GtC to the atmosphere annually.
Air Quality and Aircraft Emissions • The radiative forcing of CO2 is positive, that is, it contributes to the warming of the earth. • In 1992, aviation contributed 2.5% of the total anthropogenic greenhouse gas emissions. That amount has increased to over 3.5%• CO2 is a potent greenhouse gas partly because of its residence time which is approximately 100 years.
Air Quality and Aircraft Emissions Contrails•Contrails, or condensation trails, which are formedfrom water vapor emitted from aircraft that freezes into clouds at high altitudes, also affect global temperatures •. (Eden, n.d)
Methane• The atmospheric concentration of methane has exceeded the natural range of the last 650,000 years.• In 2005, methane was 319 ppb in comparison to 270 ppb for many centuries prior to industrial times. • It is estimated that methane produces about one-third the amount of global warming of carbon dioxide.
• Global radiative forcing (RF) estimates and ranges for anthropogenic carbon dioxide, methane (CH4), nitrous oxide (N2O), contrails and other important agents (IPCC, 2007)
Changes in Global Temperatures,Sea Level, and Snow Cover: 1850-2005 • As GHGs prevent some of the heat reradiated by Earth from leaving the atmosphere, global average temperatures rise, and snow cover declines • Excessive CO2 and other GHGs, therefore, have a domino effect on the environment
Reducing Emissions• Past measures of reducing emissions from aircraft were not extensive because adequate knowledge about climate change was not widespread• Catalytic converters were used to help reduce the amount of hydrocarbons and CO2 added to the atmosphere from automobiles • U.S. EPA: fuel volatility limits were set for all forms of transportation
Reducing Emissions• The amount of GHG emission caused by aviation could increase from 3.5% at present to a high of 15% by the year 2050 • CO2 emissions from aviation will range from 843-5,317 million tons per year by the year 2050,a significant increase from 514 million tons in 1992• Currently there are no laws on emissions at high altitudes partly because there is no strong lobby to reduce those emissions
Reducing Emissions • NextGen would reduce aircraft emissions by 10-15% by the year 2025 by using alternate fuels,newer equipment and enhanced operational procedures • If the industry continues to grow at its present rate there would be an estimated 3% increase in emissions for every 5% increase in traffic
Reducing Emissions • The IPCC has forecast that by the year 2050, fuels would be 40-50% more efficient and there will be a decrease of NOx emissions of 30-50% per aircraft• General electrics developed the GEnx engine which is designed to operate on less fuel and designed to last longer than engines of today
Conclusions • An increase in sea level is likely, longer and more intense natural events will occur. • Sulfates, PM, UHCs, contrails, cirrus, clouds, and GHGs all contribute to atmospheric warming. • The alternate hypothesis is accepted:HA: The projected increase in air travel (pass. km) will significantly increase positive radiative forcing (W/m2) from commercial aviation emissions.
Recommendations • The development of international laws for regulating emissions • The EPA could implement more stringent laws and regulations to reduce emissions • The average operating cost for a Boeing 737-400 is $2,865.00 per hour. If alternative fuel sources are used this cost will be reduced by 10% • Emissions trading• Blended Wing Body (BWB) aircraft is another type of design which is still in development.
• Historically and currently,the fossil fuel industry is the only industry that has not had to pay for dumping its waste (CO2 into the air) Is it time for a change?