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

Sustainable Development (NAS)

• A process of reconciling society’s 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.

Trend of Indicators

SOx = Pop x GDP/P x Btu/GDP x Sox/Btu

1960s

1970s

1980s

1990s

0

0.5

1

1.5

2

2.5

3

1900 1920 1940 1960 1980 2000 2020 2040

GDP(Mill$)/PersonEnergy(Bbtu)/GDP(Mill$)SOx/Energy(Bbtu)PopulationSOX Emiss

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

0

100

200

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600

1900 1950 2000 2050

Mill

ions

-3.00%

-2.00%

-1.00%

0.00%

1.00%

2.00%

3.00%

4.00%

1900 1950 2000 2050

Births Deaths Migration

Regional Population Projections

Regional Population Projections

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10000

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30000

40000

50000

60000

70000

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90000

1995 2000 2005 2010 2015 2020 2025

Year

Popu

latio

n (th

ousa

nds)

R1 - Pacif ic Coast R2 - Mountain States R3 - Southw est R4 - Great Plains

R5 - Great Lakes R6 - South R7 - Northeast R8 - Noncontinental US

Normalized Region 2 Population Projection

1

1.1

1.2

1.3

1.4

1.5

1.6

1995 2000 2005 2010 2015 2020 2025

Year

Popu

latio

n C

hang

e

Colorado Idaho Montana Nevada Utah Wyoming

*Regions split according to geographic and state growth trends

National Income by Industry Group/Person

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 < 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.

0

2000

4000

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12000

1900 1950 2000 2050 2100

Inc

om

e,

$ (

19

96

)

Res/com

Industrial

Transportation

0.00

0.20

0.40

0.60

0.80

1.00

1900 1950 2000 2050 2100

0

0.5

1

1.5

2

2.5

1900 1950 2000 2050 2100

Fraction of Total Income

Trend by Ind. Group

1970 = 1

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 < 1%

Coal Sulfur Flow in 1980 and 1998

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

Arrows indicate the flow of coal from the mines to the consumer

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

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.

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.

Trend of Average Coal S Content

• The average sulfur content of coal from each region is quite different; Eastern coal is > 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.

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.

0

50

100

150

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350

1900 1950 2000 2050

Ca

pa

cit

y,

Gig

a W

att

s

0.00

0.10

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0.50

0.60

0.70

0.80

0.90

1.00

Fra

cti

on

FGD Capacity Coal El. Util.Capacity FGD Fraction

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.

Sulfur Flow Diagram (Tentative)

Mineral Mining Production Consumption

AirLandWater

S Stocks Exp/Imp Raw

Fuel Mining Refining Combustion

Minerals Flow for GoodsMetals, Frasch, Pyrites

Fuels Flow for EnergyCoal, Oil, Gas

Exp/Imp Proc

Ex/Im Raw Ex/Im Processed

Exp/Imp AirEx/Im Water

S as Pollution S as Goods

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

US Industrial Sulfur: Supply and Demand Trend

US S Budget

S Stocks

Exp/Imp

0

2

4

6

8

10

12

14

1900 1950 2000 2050

ExportsImports

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2

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1900 1950 2000 2050

US SupplyConsumption

-2

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6

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12

1900 1950 2000 2050

Sulfur Stock

Stock Change

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2

4

6

8

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14

1900 1950 2000 2050

S RecoveredS Mined

US S Supply US S Demand

Source http://minerals.usgs.gov/minerals/pubs/of01-006/sulfur.xls

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

Total S Mobilized and Recovered

• 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

0

2

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14

1900 1950 2000 2050

Mill

ion

Ton

s/yr

CoalSMob OilSMob NGasSMobil

0

2

4

6

8

10

12

14

1900 1950 2000 2050

Mill

ion

To

ns/

yr

PetroleumSRec NatGasSRec MetalSRec

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2

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6

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14

1900 1950 2000 2050

Mill

ion

To

ns/

yr

Pyrites S Mined Frash S Mined MetalsSMob

0

5

10

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25

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35

40

1900 1950 2000 2050

S RecoveredTotMobilized

Mobilized in Fuels

Mobilized in Minerals

Recovered from Fuels &

Min.

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

Energy Consum prion per Sector

0

5000000

10000000

15000000

20000000

25000000

30000000

35000000

40000000

45000000

50000000

1900 1920 1940 1960 1980 2000 2020 2040

CE+RE(Bbtu)

IE (Bbtu) TE (BBtu)

Energy/$ in Sector

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

1950 1970 1990 2010 2030 2050

CE+RE(Bbtu)/$

IE (Bbtu)/$

TE (BBtu)/$ Tot Energy(Bbtu)/$

Energy/$, Relative Trend s ince 1970

0

0.2

0.4

0.6

0.8

1

1.2

1950 1970 1990 2010 2030 2050

CE+RE(Bbtu)/$,Norm

IE (Bbtu)/$,Norm

TE (BBtu)/$,Norm Tot Energy(Bbtu)/$,Norm

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.

SOx Emission Factor (SOx/Energy)

1. 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.

2. 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.

3. 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).

SOx per sector

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1900 1920 1940 1960 1980 2000 2020 2040

CommResTotal IndRCTR TE Total

SOx/Enegy in Sector

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1

1950 1970 1990 2010 2030 2050

CommRes SOx/ComRes EnergyInd SOx/Ind EnergyTransp Sox/ TranspEnegySox/Energy, All Sectors

SOx/Enegy in Sector, Relative Trend Since 1970

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1

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1950 1970 1990 2010 2030 2050

CommRes SOx/ComRes EnergyInd SOx/Ind EnergyTransp Sox/ TranspEnegySox/Energy, All Sectors

SOx Emission Trend By Industry Group and by Fuel/Material

0

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1900 1920 1940 1960 1980 2000 2020 2040

ElUtil Ind RecComm Transport Metals Total

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.

Emissions by Sector

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

Electric Utility & 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).

FUEL COM B. ELEC. UTIL.

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1930 1940 1950 1960 1970 1980 1990 2000 2010

SO

2, 1

00 T

ons/

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El. Util CoalTot OilTot GasTot OtherTot

0

1000

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6000

1930 1940 1950 1960 1970 1980 1990 2000 2010

Metal copper lead Ferrous Metals Processing

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.

Electric Utilities Metals Smelting

FUEL COM B. INDUSTRIAL

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SO

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Industrial CoalTot OilTot GasTot OtherTot

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.

CHEMICAL & ALLIED PRODUCT MFG

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1930 1940 1950 1960 1970 1980 1990 2000 2010

SO

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To

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/yr

Chemical sulfur compounds

Other Chemical Mfg Agricultural Chemical Mfg

PETROLEUM & RELATED INDUSTRIES

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1930 1940 1950 1960 1970 1980 1990 2000 2010

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Petroleum Petroleum Ref ineries & Related Industries other pretroleum

0

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1930 1940 1950 1960 1970 1980 1990 2000 2010

OtherInd Wood, Pulp & Paper cement mfg other

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.

Industrial Fuel Combustion Petroleum and Related Industries

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.

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0 10 20 30 40 50 60 70

Other Fuel ComCoal CommOil ResCoal ResOil

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800

1930 1940 1950 1960 1970 1980 1990 2000 2010

MiscArea Other Combustion

Emissions from other miscellaneous residential/commercial combustion and processes were relatively small, and have dropped to almost zero since 1980.

Transportation

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.

0

100

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1930 1940 1950 1960 1970 1980 1990 2000 2010

On Road Light-Duty Gas Vehicles & MotorcyclesLight-Duty Gas Trucks Heavy-Duty Gas VehiclesDiesels

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3500

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1930 1940 1950 1960 1970 1980 1990 2000 2010

NonRoad Marine Vessels Railroads Non-Road Diesel

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.

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).

SOx Emissions: Where are We Heading and What Can I Do?

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1900 1920 1940 1960 1980 2000 2020 2040

ElUtil Ind RecComm Transport Metals

Relative Emissions by Sector

Electric energy consumption account for 70% national Sox emissionsReducing electricity consumption is the most effective contribution to Sox pollution reductionOver much of the country, air conditioning and appliances are the main consumers of res/comm electric energy

Heading Toward Sustainability Some Regulations In place

Population - Energy/Goods Consumption– Materials Flow - Emissions

Ek = cjk EMj = bij cjk GEi = ai bij cjk P

Industr. Energy

Transp. Energy

ResCom.Engy

Coal

Oil

GasElectric Energy

SOx

NOx

HC

PM

Goods &Energy,(GE) i Fuels&Mater.(FM), j Emission (EM), k

Ind. Chemicals

Industr. Goods

Pop., P

Metals

Mercury

ai

Consump./Person

bij

Fuels/Energy

cjk

Emission/Fuel-

j ji i i jConsumption of Goods and Energy: GE = ai P

Fuels and Materials Flow: FM = ai bij P

Emission of Pollutants: EM = ai bij cjk P

Industrial Prod.

Transportation

ResComercial

EconMeasure(EM)

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