We didn't plan to talk about it, but since you asked...

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1 We didn't plan to talk about it, but since you asked... What information is out there for how planes effect environmental quality? CEE 3510 Environmental Quality Engineering.

2 When a jet takes off, it can produce more or less pollution than a car (over its life). Depending on:» the type of fuel» the type of engine» how the vehicle has been operated and maintained.» the speed of operation There are also different types of pollution emitted by planes vs. cars.

3 For example... A DC-10 with 3 engines produces 245 lb/hr of carbon monoxide (CO) during takeoff. A car (that meets emission standards) running at 50 mi/hr will produce 0.37 lb CO/hr. Over the entire lifetime of the car (say 150,000 mi), this car will produce about 1120 lb CO [that s 30 ten minute take offs]. Planes, however, make more nitrogen oxides (NOx) than cars, because they generally function at higher engine temperatures.

4 Types of emissions from planes CO 2 (a greenhouse gas that enhances global warming) NO X (can react to destroy methane; a cooling effect, and form ozone, a warming effect) Water vapor (condensed water drops at high altitude, i.e., contrails, have a warming effect) Particulates (soot has a warming effect) Sulfate (has a cooling effect).

5 Radiative forcing The influences of emissions on temperature can be summarized in terms of radiative forcing.» = radiant energy received by the earth minus energy radiated back to space» A positive forcing warms the system Best estimates (bars) and high-low 67% probability intervals (whiskers) are given.

6 Time scale is important CO 2 can remain in the atmosphere for centuries, slowly warming the earth. Vapor trails and tropospheric ozone have potent, short term, warming effects. We typically add up effects over a 100 year interval, and conclude cars cause more pollution than planes, but:» If you use a time scale of 5 years, then planes account for more global warming than all the cars on the world's roads. Per passenger mile, things are even more marked: flying turns out to be on average 50 times worse than driving in terms of a five-year warming impact.

7 What about a 20 year time scale? Things look completely different.» The short-term impacts have largely died down and the plane looks considerably better helped along by a quirk of atmospheric chemistry which sees NO X from the aircraft engines causing cooling during this period by destroying methane in the air.

8 Time scale of impact Temperature change per passenger kilometer for passenger travel (left) and per ton-kilometer for freight transport (right). Global average values for the year Bars represent 1 SD. Source: Borken-Kleefield et al. ES&T (2010)

9 A little more about NOx The main problem with airplanes and the emission of NOx isn t the amount produced; it s where the NOx are produced. In the troposphere (below 16 km), NOx photochemically reacts with hydrocarbons to produce ozone, which acts as a greenhouse gas. At sea level, NOx can breaks down and be washed out of the atmosphere (more on this in a minute).

10 Still more on NOx NO X in the stratosphere (above 16 km) could react with ozone, and decrease the ozone layer. Fear of the environmental damage from jets flying in the stratosphere (and noise on landing) may have caused the US to stop its development of supersonic transportation, SST, (like the Concorde). Concorde flights ceased mainly because the cost for fuel went up and demand went down after 911.

11 NOx at sea level At sea level, NOx can react with hydrocarbons and form ozone, which is a major component of smog.» Smog smells bad, causes eye irritation, and reduces visibility. When NOx are washed out of the atmosphere, they form a major component of acid rain, nitric acid (HNO 3 ).» Acid rain can lower the ph of lakes, killing off aquatic life; and also corrodes marble and limestone buildings (like the Parthenon) and statues.

12 The number of airline flights is growing rapidly The FAA projects that the number of U.S. airline passengers will nearly double from 739 million in 2005 to 1.4 billion in Air traffic controllers are expected to handle 95 million flights by all types of aircraft in 2025, compared with 63 million in By 2050, emissions from planes are expected to become one of the largest contributors to global warming.

13 Airplane pollution regulation In 2012, the European Union (EU) acted to force airlines flying into the EU to buy tradable carbon credits as part of its broader emissions-trading system. Many countries objected, including the US, and China banned its airlines from participation without specific government approval.» The China Air Transport Association, which represents China's airlines, estimated the scheme would cost them 800m yuan ($127m) in 2012, and more than three times as much by 2020.

14 Alternative fuel The U.S. military and a slew of airline companies, have invested heavily in jet fuel made from plants the oils provided by weedy camelina or hardy jatropha shrubs or even algae. The fuels have successfully passed all trials even delivering more thrust per gallon and have now entered regular commercial use in the U.S. and Europe, promising to cut CO 2 emissions by 80%, albeit at a premium price. The U.S. Federal Aviation Administration is giving out $7.7 million in contracts to jet biofuel makers.

15 Your transportation choices and their environmental impact Based on a report from the Union of Concerned Scientists

16 Your acronym goes here