Sources
Reading: Mobile Chap 15
9/13/11
Types of mobile sources
Impact of mobile sources
Emission standards
Types of engines: gasoline vs diesel, 4-strokes vs
2-strokes
Emission Control: technology and policy
Add-on Control Device catalytic converter
Hybrid Vehicles and Fuel Cells
Aerosol & Particulate Research
Aerosol & Particulate
11
Types of mobile sources
Ship track resulting from stack
emission
Gasoline Automobiles
Diesel Trucks/Buses
Aircraft
Q: Others?
http://earthobservatory.nasa.gov
Impact of Mobile sources vs Stationary sources
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Monitor
Number
Distance to receptors
Non-steady: cold-start emission, idling, stop & go
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Emission Standards
CAA
1977 CAAA
1990 CAAA
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Asif Faiz et al., 1996,
Air Pollution from Motor
Vehicles
33
Q:
NMOG?
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Q: Gasoline vehicles for ULEV and
ZEV?
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44
Heavy Duty Vehicles
For the same power output, only 70% mass compared to
gasoline engines
Less volatile, Lower CO2 emission
Lower operating cost, 2/3 of an equivalent gasoline truck
VMT: Vehicle Miles
Traveled
Lloyd and Cackette, JAWMA, 51, 2001, p809847.
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Q: Gasoline penalty in Europe?
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Heavy Duty Vehicles (cont.)
Contains S (500 ppmw): new regulation just kicked in 2006
Lower operating speed, slower thrust/acceleration
Lean exhaust: catalytic converters dont work
Also standards for PM, smoke opacity
Account for 5% of vehicles, account for 35% visibility
reduction; Off-road vehicles emit 2 times PM
(regulated in CA from 1996)
Soot from diesel engines is the 2nd largest contributor
to global warming
Relative health risk of diesel exhaust exposure ~ 1.4
Q: Emission regulations for diesel engines?
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Heavy-Duty Truck and Bus Engine
Emission Standards
EPA 1998 Standards
Heavy-Duty Diesel Truck
Engines
Urban Bus Engines
HC
1.3
CO
15.5
NOx
4.0
PM
0.10
1.3
15.5
4.0
0.05
CA Standards
NMHC
1.2
THC
1,3
CO
15.5
Heavy-Duty Diesel Truck
Engines (1994)
Urban Bus Engines (1996)
1.2
1.3
15.5
EPA Standards for MY 2004
NMHC+NOx
Option 1
Option 2
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PM
0.10
4.0
0.05
NMHC
2.4
2.5
NOx
5.0
n/a
0.5
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Motorcycles
Small number in US (0.6% of HC, 0.1% NOx
and <0.1% of PM of all mobile sources); large
in developing countries
Higher emissions per mile than a car or even a
SUV
Thailand Tutu
Highway Motorcycle Exhaust Emission Standards
Class Engine Size
(cc)
Implementation
Date
HC
(g/km)
HC+NOx
(g/km)
CO
(g/km)
I
< 170
2006
1.0
-
12.0
II
170-279
2006
1.0
-
12.0
III
> 280
2006
-
1.4
12.0
2010
-
0.8
12.0
http://www.epa.gov/otaq/roadbike.htm
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4-Stroke Internal Combustion
Animation: http://www.allstar.fiu.edu/aerojava/pic6-3.htm
Premixed gasoline
vapor
Combustion occurs
every two revolutions
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Octane Rating
A measure of gasolines resistance to engine knock (rattling or
pinging sound in cylinders due to premature burning)
Heptane: 0 C
Iso-octane: 100
C C C C C C
C
http://en.wikipedia.org/wiki/Image
C C C C C
C
C
Anti-knock agents: Tetraethyl lead (Pb(C2H5)4), highly
branched alkanes, aromatics
(R+M)/2: Research Octane Number (RON): test engine running at
600 rpm; Motor Octane Number (MON): test engine at 900 rpm
Q: What if a lower grade than required is used?
Q: Does my car perform better if I use a higher grade than required?
Q: Why is octane rating lower at higher altitudes?
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2-Stroke Engine
Compression stroke
Power stroke
http://media-2.web.britannica.com/eb-me
Q: Why two strokes are not good?
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Liquid diesel injection
700 900 oC
from compression
Ignition
delay
Diffusion
flame
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Emission Control
Engine design, vehicle
shape, tire friction
Fuel composition
Octane rating, oxygenated
fuel
Fuel desulfurization
Alternative fuel
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natural gas, liquefied
petroleum gas, methanol,
ethanol , bio-diesel,
hydrogen
Transportation control
Regulatory steps, public
transportation, economic
incentive
Regulation: Inspection
Add-on control
Alternative power
generation
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Solar, Electrical, Fuel Cell,
Hybrid
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Vehicle Shape: Aerodynamic
Cd
0.02
Object
F4 Phantom fighter
jet
0.024
Boeing 787
0.031
Boeing 747
0.18
Mercedes-Benz T80
0.19
GM EV1
0.25
Honda Insight
0.26
2008 Toyota Prius
0.29
2004 Honda Accord
0.57
2003 Hummer H2
1.0-1.3
Dr. Wu (upright
position)
http://en.wikipedia.org/wiki/Drag_coefficient
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Asif Faiz et al., 1996,
Air Pollution from Motor
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Tire Friction
Proper tire inflation
Tire rolling resistance: 20% of energy to move
the vehicle (4% of world wide CO2 emission)
Green tires based on silica reduced rolling
resistance 30% compared to carbon-black based
conventional tires.
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Lower rolling resistance for better fuel economy
Safety concern: wet-road grip
Noise
Solid rubber tire: 30 kg/ton
construction 20 kg/ton
pneumatic tires
25 kg/ton Tire cord
radial tires (carbon based) T 15 kg/ton
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Oxygenated Fuel & Fuel Desulfurization
Oxygenated fuel: mainly ethanol, (MTBE)
Oxygen content in the fuel improves oxidation and
results in less CO
Q: Is oxygenated fuel requirement for summer or winter?
Fuel Desulfurization
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S poisons catalyst in catalytic converter
SO2 emission
Gasoline sulfur: 80 ppm per gallon cap in US (delays
in Rocky Mountain area); 30 ppm for CA; 10 ppm for
EU
Diesel sulfur: 15 ppm
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Alternative Fuel
Natural Gas (mainly CH4 ; Octane rating 120) & Liquefied
Petroleum Gas (LPG; C3H8 and C4H10; Octane rating
105)
Similar energy density per unit mass (not volume) to
gasoline but requires compression or refrigeration to
maintain them in the liquid phase
50% less CO and VOCs
No photochemically active VOCs and no air toxics such as
http://en.wikipedia.org/wiki/Liq
benzene
Issues: onboard fuel storage; handling and refueling
Methanol (CH3OH; Octane rating 112)
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Low photochemical activity; relative inexpensive
Lower energy density per unit mass (40% of gasoline):
shorter driving distance and more frequent refueling
Handling: dissolve rubber; toxic
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Ethanol as an Alternative Fuel
E85
blend of 85% ethanol and 15% gasoline
Requires flexible-fuel vehicles (9.3 million on the road in 2010 in
US; same price as regular vehicle)
2423 stations in USas of Oct/2010 (tax credit for retrofit)
Q: Whats driving E85 into the market? Does it
improve air quality?
Production
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Mainly made from corn in US (current capacity accounts for 3%
www.mnsu.edu/news/read.php?id=old-1149701286
gasoline consumption)
Federal subsidy
Q
Research on biomass conversion: cellulosic : Drawbacks?
technology
Mainly from sugarcane in Brazil
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Bio-diesel
Non-petroleum-based diesel fuel consisting of short chain alkyl (methyl
or ethyl) esters, made by transesterification of vegetable oil or animal
fat (tallow), which can be used (alone, or blended) in unmodified
diesel-engine vehicles
Transeterification: separate the fatty acids from the glycerol by
replacing the glycerol with short linear alcohols; typically requires
liquid catalyst
Distinguished from the straight vegetable oil (SVO) used (alone, or
blended) as fuels in some converted diesel vehicles
Advantages: in reduction greenhouse gases; no sulfur; better lubricity
Disadvantages: slightly lower energy density; may contain water;
cloud point (gelling) higher the petroleum diesel; by-product glycerol;
more expensive
Emissions (B20):
PM
HC
CO
Algae as a feedstock
10%
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21%
11%
NOx
2%
http://en.wikipedia.org/wiki/Biodiesel
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Traffic Congestion
In 2007, $87.2 billion drain on US economy, including
2.8 billion gallons of fuel
4.2 billion lost hours
Annual extra time on the roads
Rank Metro area
Hours
1
Los Angeles
72
2
San Francisco
60
2
Washington, DC 60
2
Atlanta
60
8
Orlando
54
11
Miami
50
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Data provided by Texas Transportation Institute,
http://mobility.tamu.edu/ums/
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2020
Catalytic Converter (Gasoline)
Pt, Pd
Two-way
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Bloomfield, L., Scientific America,
2001
2121
Pt, Rd
Three-way
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Trade-off
Work in rich environment; temperature sensitive
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Older model
Q: Cold-start emission more
serious? How to control it?
Newer Model
(1980s in US)
O2 for lean
environment
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Clean School Diesel Bus Technology Options
Clean Fuel / Type of Engine
Clean Tech
Ultra-Low Sulfur Diesel
New or Used
(ULSD)
% Reduction in % Reduction in
PM Emissions NOx Emissions
About 5 to 9% N/A
Enables the PM
filter to work
Approximate Cost of Technology
8 to 25 cents per gallon more than
regular diesel now
In June 2006, when ULSD will be
required nationwide, cost differential
will be much less
Particulate Matter Filter
New or Used - 60 to 90%
1995 or newer
models
Oxidation Catalyst or Used 20 to 30%
New
N/A
$5,000 to $10,000
Must use ULSD fuel
N/A
$1,000 to $2,000 and can be used
with regular diesel
Biodiesel FuelNew or Used
B100 - 40%
Biodiesel increases B20 - 15 to 30 cents per gallon more than
NOx emissions of. regular diesel
B20 blend +2%
B100 - 75 cents to $1.50 per gallon more than
regular diesel (B100 may not be an option for
B100 fuel +10%
cold climates)
About 50%
About 10%
Emulsified Diesel Fuel
New or Used
B20 - 10%
20 cents per gallon more than
regular diesel fuel
http://www.epa.gov/cleanschoolbus/technology.htm
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Diesel Emission Control
Diesel PM Filter: Block Flow Filter
http://www.epa.gov/nonroaddiesel/2004fr/pmfilters.htm
http://www.epa.gov/cleanschoolbus/images/pmfilter.jp
g
Lean NO catalyst:
Zeolite catalyst to reduce NO
Combined with lean-burn engine
HC + NO Zeolite CO2 + N 2 + H 2O
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Aerosol &
http://www.sinofilter.cn/admin/upfile/2009530203359.jpg
Particulate
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Electric Car
Thomas Edison and an electric car in
1913 (National Museum of American
History)
Q: Is it really zero emission?
First electric car in 1835 by Professor Sibrandus
Stratingh of Groningen, Netherlands
First battery powered electric car in 1881 by
Camille Faure in France
Lost market to ICE circa 1910
Government backed promotion (tax credit)
revived electric car
Who killed the electric car (EV1)?
http://www.pbs.org/now/shows/223/
Q: Why isnt it commonly used?
Plug-In: uses a wall socket at night to charge and relies on an electric motor to go many
miles before sipping any gasoline good for short-distance driving in cities
Q: Where do you find a wall socket when not at home?
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Electric Car
2011 Nissan Leaf
First 5-door family car
Li ion battery: 100 miles on a
single charge
Charging dock (220 V): 8 hr.
80% recharge in 30 min
Cheaper to run per mile than gasoline
http://money.cnn.com/2010/11/09/autos/electric_car_b
enefits/index.htm
2010 Tesla Roadster
First (2008) highway capable sedan in
constant production
Li ion battery: 245 miles on a single
charge
Charging dock (220 v): 3.5 hrs. 80%
repaid recharge in 30 min
teslaelectriccar.jpg
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Hybrid Electric Vehicle
Use 2 sources of motive energy:
combustion of gasoline (Internal
Combustion Engine) & electrical
energy (Electric Motor energized by
a Battery)
ICE for highway driving
EM provides added power during
hill climbs, acceleration, and other
periods of high demand
http://gmvolt.com
Automobile.Honda.co
m
Regenerative Braking: converts
some of the kinetic energy into
electric energy; electric motor
becomes a generator for battery
Also available for heavy-duty
hybrid vehicles (diesel-electric)
http://www.nrel.gov/vehiclesandfuels/ahhps/
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http://1st-in-hybrid.com/.../07/volvo-hybrid-truck.jpg
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Advantages of Hybrid Electrics
high performance
Fuel economy
long-range capacities
Lower emissions
high fuel efficiency
2007 Ford Focus
MPG(city)
MPG(highway)
2007 Toyota Prius
27 MPG(city)
37 MPG(highway)
2007 Honda Hybrid
51 MPG(city)
60 MPG(highway)
Plug-in Hybrid:
Lithium ion battery
Charging time: 10 hr on 120 V, 4 hrs on 240 V
Q: Is hybrid popular?
Cost: federal and state purchase incentives
Driving privileges
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49
51
Fuel Cell Operation
http://en.wikipedia.org/wiki/Fuel_cell
http://www1.eere.energy.gov/hydrogenandfuelcells/
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University of Florida Fuel Cell Research Lab
H2 source:
H2 (gas, liquid, solid
hydride)
Converted from other
energy sources (coal,
solar, wind)
Methanol (CH3OH)
Gasoline
Limitation of H2 fuel
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Pipelines needed to convey hydrogen fuel not currently in place
Retail fueling facilities must be placed throughout Q: Where?
Danger of H2 explosion (although gasoline explosion is also dangerous)
Requires construction of hydrogen production facilities
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Hydrogen Fueling Station
BP-Praxair H2
Station
Washington, DC (1st in US)
74 stations in 23 states as of Nov 09; 43
planned
4 stations in FL
Honda solar-powered water
electrolyzing H2 station
www.hydrogenassociation.org/.../bpStation.jpg
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H2 fuel station in Iceland
http://www.cnn.com/2007/TECH/scie
nce/09/18/driving.iceland/index.html
http://green.autoblog.com
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Methanol as an Alternative to Hydrogen
Some production facilities already exist
Distribution facilities can accommodate with slight
modifications
Dispensing facilities can accommodate with only slight
modifications
Currently there is an abundance of methanol
Steam Reforming Equilibrium Reaction at 1atm and
300oC:
CH3OH + 1.5H2O
2.896H2 + 0.896CO2 + 0.104CO + 0.603H2O
Catalyzed by Phosphoric Acid Membrane (PAM)
Q: Are fuel cells used in stationary sources?
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Evaporative Loss Refrigerant
CFC (Chlorofluorocarbons) Ozone depleting chemical
phased out starting from 1987 Montreal Protocol
Replacement: HCFCs (Hydrochlorofluorocarbons)
HFCs (Hydrofluorocarbons)
Q: Impact of stockpile and CFC in discarded units?
Further ban on global warming gases
Compound
CO2
CFC-12
HCFC
HFC-134a
GWP
1
8500
13007000
1300
http://www.epa.gov/ozone/ods.html
http://pubs.acs.org/isubscribe/journals/cen/8
3/i18/html/8318gov2.html?
emFrom=emLogin
EU: HFC-134a banned in new cars in 2011; any other
fluorinated gas with a GWP > 150 in all vehicles in 2017
US: HCFCs in new appliances restricted from 2010
Replacement: nontoxic and nonflammable
CO2 (requires new systems); DP-1 (GWP-40); Fluid H
(GWP-10)
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Quick Reflection
The stone age did not end because the world ran out of
stones.
The oil age won't end because the world runs out of oil. Shiek Yamani
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