The Greenhouse Effect
CE 326 Principles of Environmental Engineering
Prof. Tim Ellis
January 28, 2008
Greenhouse Effect
Greenhouse effect: n_______
effect of the gases in earth’s
atmosphere to trap incident solar
radiation
earth is an average of ____ ̊C
warmer than if no greenhouse effect
average earth temp would be ____ ̊C
instead of current ____ ̊C
Global Warming
Global warming: t_______ that the
accumulation of specific gaseous
compounds is causing an
uncontrollable increase in the earth’s
temperature with potentially
devastating g_______ effects
What is Known
naturally occurring greenhouse gases include
w______ vapor, carbon dioxide, methane, nitrous
oxide, and ozone
concentrations of most are increasing due to
a______________ sources
water vapor is the most a__________
greenhouse gas, but its concentrations are
closely related to global temperatures and are
relatively constant
P_________ of high concentrations of CO2 in past
history of the Earth have been accompanied by
high temperatures at the Earth’s surface, and
periods of low carbon dioxide had relatively low
surface temperatures.
http://www.meteor.iastate.edu/gccourse/model/co2/seedsci.html
What is known
sea level has risen 4-8 inches over the past
century
global mean surface temperatures have increased
0.25-0.5 C since the late 19th century
Greenhouse gases have long lifetimes, ranging
from ____ years for methane to about _____ for
carbon dioxide to ______ years for nitrous oxide.
Anthropogenic increases in these gases could
influence the earth’s climate for many centuries.
The climate system has high i_______, primarily
due to the long time scales of ocean dynamical
processes.
http://www.meteor.iastate.edu/gccourse/model/co2/seedsci.html
What is known
S__________ particles that form
from sulfur dioxide emitted primarily
by the burning of coal contribute to
local cooling although the magnitude
is uncertain.
Decreases of ozone in the lower
stratosphere have contributed to
c_______ effects in that region.
http://www.meteor.iastate.edu/gccourse/model/co2/seedsci.html
What we think will happen
the stratosphere will continue to c_____
as CO2 concentrations r____. Ozone
depletion will add to the cooling.
water vapor in the lower troposphere (0-3
km) will increase about ____% for every
1oC of warming. Relative humidities will
stay approximately the same.
The warming of the last c_______ is
consistent with model projections of global
warming due to CO2 modified by the
regional cooling effect of sulfate particles.
http://www.meteor.iastate.edu/gccourse/model/co2/seedsci.html
What we think will happen
D_________ of CO2 over pre-industrial levels
(likely to occur in the later half of the 21st
century unless emissions are significantly
reduced) is projected to lead to a global warming
of 1.5 to 4.5oC (2 - 8oF).
by 2100 we can expect temperature increase of
_____oC to ____ oC.
Sea-level rise is most likely to be ___ (+/-25) cm
by year 2100 with continued rise beyond that
time highly likely. Continued high (quadrupled)
CO2 could lead to ___+/- m rise in sea level.
Global mean precipitation will increase at ____
(+/-0.5)% per 1oC of warming.
http://www.meteor.iastate.edu/gccourse/model/co2/seedsci.html
Is there a scientific debate over
man-made global warming?
Water vapor
constitutes Earth's
most significant
greenhouse gas,
accounting for about
95% of Earth's
greenhouse effect
(4).
Melting the ice cap
was a “solution”
Global cooling was the
consensus view in the
1970’s, as was a 10 year
supply of oil, and the
“population bomb.”
The limits-to-growth crowd has predicted the end of oil since the days when
this black gold was first discovered as an energy source in the mid-19th
century. In the 1860s the U.S. Geological Survey forecast that there was "little
or no chance" that oil would be found in Texas or California. In 1914 the
Interior Department forecast that there was only a 10-year supply of oil left;
in 1939 it calculated there was only a 13-year supply left, and in 1951 Interior
In the
warned that by the mid-1960s the oil wells would certainly run dry.
1970s, Jimmy Carter somberly told the nation that
"we could use up all of the proven reserves of oil in
the entire world by the end of the next decade."
Don’t just do something,
stand there!
Air Pollution Meteorology
Atmospheric Engine
– atmospheric s_______ (and
weather) is a function of
t___________ and
p__________
– wind flows from h____ pressure
areas to l_____ pressure areas
– in absence of earth’s rotation,
wind would be p___________
to constant pressure lines
(i_________)
– earth’s rotation creates
C_______ effect
Atmospheric stability
tendency of atmosphere to r_____ or
e_________ vertical air movement is
termed s_______
there are three categories of stability
depending on the l_____ r____
– rate of temperature change as a function of
elevation
neutral – d____ a________ l____ r____
unstable – s_________ lapse rate
stable – s__________ lapse rate
– isothermal – no change in t___________ with elevation
– i________ – temperature increases with elevation
Terrain Effects
H____ I_______
E______
– mass of material that
a________ and e_____
heat at a greater rate
than surrounding area
– stability over heat
islands is l______
good for g_______
l______ sources
bad for t____ s______
Land/Sea Breeze
land c_____ more
rapidly at night than
sea
– l_______ breeze land
land h_____ faster
during day
– s____ b_________
Valleys
valleys at an a______ a____ to
the prevailing wind will direct a
portion of wind into the valley
valleys oriented in the n____-
s______ direction are more
susceptible to inversions than
east-west direction
during daytime sun heats valley
floor
– v________ breeze
during night
– h____ breeze
early day
– i________ possible
Air Pollution Control Devices
A________ tower
B__________
C____________ Separator
aD___________ Bed
E______________ precipitator
V___________ scrubber
Air Pollution Control Devices
Absorption Tower (Packed Bed, Spray Tower, Wet Scrubber)
– D________ of the pollutant gas to the surface of the liquid
– T_______ across the gas/liquid interface (dissolution)
– D_______ of the dissolved gas away from the interface into
the liquid
– Henry’s law:
P = HCl
– where:P = equilibrium partial pressure of gas, kPa,
H= Henry's law constant, kPa⋅m3/g
and Cl = concentration of pollutant gas in liquid
phase, g/m3
– want to maximize gas liquid contact by maximizing surface
area
– efficiency will be limited by the solubility of the pollutant
Baghouse
same principle as the h_____ v______ c_______
bags are cleaned periodically as the p______ d___
across the bag becomes excessive (approximately
every 2 hours)
– cleaned by mechanical r_________ (used for shake-deflate
design)
– cleaned by h____ p_________ air jets (used for pulse jet
design)
must be a d____ gas stream
potential f____ hazard
bag "r______" with time
– develops a fine mat which helps to screen out particles
for p________ removal, or used in conjunction with
F____ G____ D_____________ (FGD) applications
Cyclone Separator
used for particulates larger than ___ μm
gas stream is accelerated through a s___
m_____, centrifugal force moves heavier
particles out and down
as the d_____ of the cyclone is reduced,
the efficiency increases (as does the
pressure drop)
use of m________ tubes in parallel
(multiclones) improves efficiency
Adsorption Bed
surface p__________
p______ or c________
bond with the surface
adsorbents: activated
c_____, activated
a_____, silica gel, and
others
1 ounce of activated
carbon has a surface area
of ______ acres
bed must be r________
prior to breakthrough
Electrostatic Precipitator
w____ in t____ or wire and
p____ configurations
wet or dry, wet cleaned by
w______ s____, dry by
rapping, can be cleaned
while in service
c_______ wire imparts an
electrical charge (neg),
particles are attracted to
charged (pos) collecting
plates
high p__________ removal
efficiencies possible
Venturi Scrubber
velocity of gas is a_________
by a factor of four in the throat
section where nozzles inject
water or solution
high velocity causes
a__________ of liquid
pressure drop following the
t________ section creates a lot
of turbulence resulting in good
intermixing
requires s_________ (e.g.,
cyclone) following venturi to
collect particles and liquid
Thermal Incineration
