Class Project Report, May 2003 ME/ChE 449 Sustainable Air Quality

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Class Project Report, May 2003 ME/ChE 449
Sustainable Air Quality

• Causality of US Sulfur Production and Emission
  Trends
• By
• James Agan, Kate Miller, Cat Reid, Jason Reynolds
• Instructor
• Rudolf B. Husar
• Washington University, St. Louis, MO

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Sustainable Development (NAS)

• A process of reconciling societys developmental
  needs with the environmental limits over the long
  term. It includes differing views on what should
  be developed, what should be sustained and over
  what time period.
• Human activities exert pressures, such as burning
  fossil fuels that alter the state of environment,
  such air quality. The impaired environmental
  state, elicits responses, such as regulations in
  a Pressure-State-Response (PSR) feedback loop
  system.
• These three classes of variables can be measured
  using data that are collected for administrative
  purposes. Combining these data with a simple but
  flexible scenario captures a fundamental idea of
  sustainable development
• The NAS (1999) describes SD as an uncertain and
  adaptive process, in which society's discovery
  of where it wants to go is intertwined with how
  it might try to get there. During the journey,
  the pathways of a transition to sustainability
  have to be navigated adaptively at many scales
  and in many places.

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Trend of Indicators
1960s
1970s
1980s
1990s

• SOx Pop x GDP/P x Btu/GDP x Sox/Btu

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US Population Trends

• In the 20th century, the US population has grown
  from 80 to 300 million
• In As the birth and migration rates are greater
  than the death rate, the US population will
  continue to increase in the future
• However, these rates are expected to stabilize
  over the next 50 years
• Birth rate 1.5/year
• Death rate 1/year
• Migration rate 0.25/year

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Regional Population Projections
Regions split according to geographic and state
growth trends
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National Income by Industry Group/Person
Fraction of Total Income
Trend by Ind. Group 1970 1

• The income of the res/comm sector has grown a the
  fastest rate, 10-fold since 1930, more than
  doubling since 1970.
• The industrial and transportation sectors have
  grown lt 30 since the 1950s.
• It appears that the industrial and transportation
  sectors will remain fairly steady over the next
  20 years, while the res/com curve will continue
  its rise before slowly leveling.

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Sulfur Transfer by Fuels and Minerals Theory

• An understanding of the flow of sulfur is
  paramount in moving toward sustainability.
• Know how much is produce, how much flows to the
  consumer, and how much makes it to the receptors
  provides a way to monitor and catch the sulfur
  before it makes it into the atmosphere, water,
  soil and etc.

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Coal Production and S Content

• Significant coal production is in the west with a
  much lower sulfur concentration, allowing for
  less sulfur pollution without decreasing
  consumption.

• The high concentration of sulfur is found in the
  eastern coal mined in the US.
• Sulfur in Western coal is generally lt 1

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Coal Sulfur Flow in 1980 and 1998
Arrows indicate the flow of coal from the mines
to the consumer

• In 1980, a major flow of sulfur in coal
  originated in Illinois and was transported to
  Florida

• By 1990, the transport of high sulfur coal from
  the Midwest has bee replaced by low sulfur
  western coal

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US Coal Production by Region

• Coal production in the US occurred over five
  major producing regions.
• The coal production over the eastern US has
  remained roughly constant throughout the century.
• The sharp increase since the 1980s is due to the
  addition of western coal.

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Trend of Average Coal S Content

• The average sulfur content of coal from each
  region is quite different Eastern coal is gt 1,
  western coal is 0.5 S.
• This average content has remained fairly constant
  for each region since it is determined by
  geological factors.
• Therefore, the dip in the national average sulfur
  content must be a direct result of the change in
  the source of sulfur, ie, more coal from the west
  is being used.

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Flue Gas Desulfurisation (FGD) of El. Util. Coal

• This figure shows the impact that FGD,
  (scrubbers) on coal fired power plant emissions
• Since the 1970s when they were first used,
  scrubbers have steadily increased in capacity.
• Currently (2000), scrubbers remove about 30 of
  the sulfur from the flue gases.
• Hence, sulfur is being reduced both before (low
  sulfur coal) and after (scrubbing) the coal is
  converted to energy.

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Sulfur Recovery

• Nature recycles the its sulfur, thus reaching a
  sustainable level for life.
• Man has not reached a sustainable level for
  sulfur, because the amount recovered has not been
  good in past years.
• The amounts recovered has drastically changed
  over the year especially in some sulfur producing
  processes moving us to sustainability.

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Sulfur Flow Diagram (Tentative)
Minerals Flow for Goods Metals, Frasch, Pyrites
Exp/Imp Raw
Exp/Imp Proc
Mineral Mining
Production
Consumption
S as Pollution
S as Goods
Exp/Imp Air
Ex/Im Water
Air
Land
Water
Fuel Mining
Refining
Combustion
Fuels Flow for Energy Coal, Oil, Gas
Ex/Im Raw
Ex/Im Processed
Sulfur flows into the environment through (1)
direct mining byproduct of metals (2) energy
sources, such as coal, oil and natural gas Within
these sources, there is some recycling and
recovery of sulfur Un-recovered sulfur is then
released to the air, water, and soil environment
as pollution
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US Industrial Sulfur Supply and Demand Trend
US S Supply
US S Demand
US S Budget
Exp/Imp
S Stocks
Although the US was a leading source of mined
sulfur, this industry has virtually
disappeared The use of recovered sulfur has
negated much of the need for mined raw sulfur The
stocks of sulfur have decreased from about 4
Mtons in the 1930-70 period to virtually zero
However, the US consumption of sulfur exceeds
that produced through environmental recovery, so
over the past 25 years, it has imported sulfur
Source http//minerals.usgs.gov/minerals/pubs/of01
-006/sulfur.xls
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Total S Mobilized and Recovered
Mobilized in Minerals
Mobilized in Fuels
Recovered from Fuels Min.

• Most of the S mobilization is driven by fuels,
  particularly coal (10-15 Mtons/yr)
• Mined elemental sulfur peaked around 1970 but
  became insignificant by 2000
• Recovered sulfur, especially from petroleum
  refining, has increased dramatically since 1950
• The overall flow of mobilized sulfur has
  increased steadily until about 1970 followed by a
  downturn

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Energy Consumption and Energy/

• Since 1950, the energy consumption has increased
  at similar rates in all sectors
• Energy use/ is the largest in the transportation
  and smallest in the ResComm sector
• The energy use/ of the industrial sector has not
  changed substantially since the 50s

Over the past 50 years, the the energy/ of the
entire economy has has improved by about 30. The
transition from smokestack (industrial) to less
energy-demanding ResComm economy was a major
factor.
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SOx Emission Factor (SOx/Energy)

• Up to the 1980s, the dominant emissions-sector
  was the Industry, but its emissions have declined
  rapidly since about 1970. In fact, by 2000,
  ResComm emissions exceed the Industry values.
  Transportation is not a significant SOx emitter.
• The SOx emissions per energy use has steadily
  declined by a factor 2-3 in all sectors. The
  sharp decline in the transportation SOx emissions
  in the 1950s is due to the transition from coal
  to diesel locomotives.
• It is important to note that these indicators may
  not show the whole picture, as some of the Sox in
  each sector is due to material flow rather than
  energy use, and the energy use can be direct or
  indirect (electric utilities).

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SOx Emission Trend By Industry Group and by
Fuel/Material
Emissions by Sector
The majority of emissions come from coal use,
which peaked in the 1970-90 period. Oil
products, metal smelting and industrial chemicals
were also major contributors, but their emissions
have declined rapidly since the 1970s.
The total national SOx emission trend shows a
see-saw pattern over the past 60 years. The peak
in the 1940s was due to intense industrial and
res/comm activity. The peak emission of 30
million Tons/yr of around 1970 was mainly due to
electric utilities. In fact, electric utilities,
which tend to be coal-powered, account for
increasing fraction of the tional Sox emissions,
reaching 70 in the 1990s
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Electric Utility Metals Smelting
Electric Utilities
Metals Smelting

• Looking closer at the electric utilities, we see
  that the vast majority of emissions from electric
  utilities are from the use of coal.
• The recent decrease in Sox emissions from this
  source is due mostly to switching to coal with a
  lower average sulfur content (western coal).

Emissions from metals smelting has been
drastically reduced since 1970, even more than
the electric utilities. This is primarily due
to increased recovery of sulfur from the smelting
process.
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Industrial Fuel Combustion
Petroleum and Related Industries
In the industrial sector, emissions from direct
energy use tend to be dominated by emissions from
coal. This has decreased, in part because
energy is increasingly supplied by the electric
utilities
The petroleum industry in particular has been
successful in recovering sulfur from their
material flows, and thereby reducing emissions
steadily.

• The contributions of material flows from other
  industries are significantly smaller (1 MT/yr)
  than those from energy use (10 Mt/yr)
• In general, these miscellaneous industrial
  emissions have been non-increasing.

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Commercial-Residential

• In the commercial/residential sector, Sox
  emissions from fuel use have declined
  significantly, primarily due to the fact that
  most energy is now supplied by the electric
  utilities.
• Also, there was a switch from dirty coal to
  cleaner oil.

Emissions from other miscellaneous
residential/commercial combustion and processes
were relatively small, and have dropped to almost
zero since 1980.
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Transportation
On Road Transportation
Non-Road Transportation
Road vehicles, contribute to Sox emissions
primarily through diesel vehicles However, by the
1990s, diesel emissions have declined to level of
gas fueled vehicles.

• The non-road Sox emissions came historically from
  the use of coal in railroads, and has decreased
  with their fall from favor as a means of
  transportation.

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SOX Emission Factors for Industry Groups

• With this detailed analysis, we can revisit
  trends in emissions factors (Sox/energy) and
  summarize
• The industrial and res/comm sectors both
  illustrate decreases in direct fuel use and an
  increased use of electricity.
• The emissions factor for res/comm direct fuel use
  has decreased more significantly because it is
  now dominated by oil use rather than coal (as in
  the industrial sector).
• The overall emissions factor decrease, even with
  electricity added in, is indicative of how the
  electric utilities have decreased
  emissions/energy by switching to lower sulfur
  content coal. This can also be seen in the
  emissions factors for fuels (left).

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SOx Emissions Where are We Heading and What Can
I Do?
Relative Emissions by Sector
Heading Toward Sustainability
Some Regulations In place
Electric energy consumption account for 70
national Sox emissions Reducing electricity
consumption is the most effective contribution to
Sox pollution reduction Over much of the country,
air conditioning and appliances are the main
consumers of res/comm electric energy
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Population - Energy/Goods Consumption Materials
Flow - Emissions
Goods Energy,(GE) i
FuelsMater.(FM), j
EconMeasure(EM)
Emission (EM), k
SOx
Industr. Goods
Metals
Industr. Energy
NOx
Ind. Chemicals
Industrial Prod.
Pop., P
Transp. Energy
Coal
HC
Transportation
ResCom.Engy
Oil
PM
ResComercial
Gas
Electric Energy
Mercury
ai Consump./Person
bij Fuels/Energy
cjk Emission/Fuel-

• Ek S cjk EMj S S bij cjk GEi S S S ai
  bij cjk P

j
j
i
i
i
j
Consumption of Goods and Energy GE S ai P
Fuels and Materials Flow FM S S ai bij P
Emission of Pollutants EM S S S ai bij cjk P
The causal driver to pollutant emissions is the
human population    These emissions result from
energy and material processes, which are driven
by economic sectors       The causal factors of
anthropogenic Sox emissions can be traced by this
chart