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P2.4

Your responses to your three chosen prompts should be at least 350 words each. No title page is needed, but be sure to indicate which writing prompts you are addressing at the top of each response. Each response needs to follow APA guidelines and each response needs its own reference page.

Writing Prompts (respond to ALL three):

1. Review the Reading Assignment titled as "Pollution Prevention Practices in Oregon's Electronics Industry" by Harding and Jones. In your review, include:

 an overview of the article,

 benefits of using pollution prevention in the electronics industry,

 specific process modifications discussed in the article,

 chemical substitutions mentioned in the article,

 economics of making the suggested changes, and

 reasons companies might not embrace pollution prevention.

2. Review the Reading Assignment titled as "Optimal Deployment of Emissions Reduction Technologies for Construction Equipment" by Barl, Zietsman, Quadrifoglio, and Farzaneh. In your review:

· Write an overview of the article.

 Describe hydrogen enrichment (HE), selective catalytic reduction (SCR), and fuel additive (FA) technologies.

 Describe the advantages and disadvantages of HE, SCR, and FA, including a discussion of costs.

 Does the computer model do a satisfactory job of determining the best technology? Explain.

 What would be your recommendations as far as which technology (HE, SCR, and/or FA) should be used, or should none be used?

3. Review the Reading Assignment titled as "Flue Gas Desulfurization: The State of the Art" by Srivastava and Jozewicz. In your review:

 Write an overview of the article.

 Describe flue gas desulfurization (FGD) at coal-fired power plants and why it is used.

 Explain the details of one once-through process and one regenerable process.

 Summarize the section titled "The MEL [magnesium enhanced slurry] Cost Model."

 Discuss how the article is useful to a pollution prevention manager.

 Conduct an Internet search to explain the concept of Best Available Technology (BAT) and whether any of the FGD processes described in the article are considered BATs.

All sources used must be referenced; paraphrased and quoted material must have accompanying citations. Prompts will be scanned through plagiarism software for originality.

Flue Gas Desulfurization The State of the Art.pdf
Journal of the Air & Waste Management Association ISSN: 1047-3289 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/uawm20 Flue Gas Desulfurization: The State of the Art
R. K. Srivastava & W. Jozewicz
To cite this article: R. K. Srivastava & W. Jozewicz (2001) Flue Gas Desulfurization: The State
of the Art, Journal of the Air & Waste Management Association, 51:12, 1676-1688, DOI:
10.1080/10473289.2001.10464387
To link to this article: http://dx.doi.org/10.1080/10473289.2001.10464387 Published online: 27 Dec 2011. Submit your article to this journal Article views: 3036 View related articles Citing articles: 78 View citing articles Full Terms & Conditions of access and use can be found at
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Download by: [208.54.37.164] Date: 11 August 2016, At: 08:18 Srivastava andPAPER
Jozewicz
TECHNICAL ISSN 1047-3289 J. Air & Waste Manage. Assoc. 51:1676-1688
Copyright 2001 Air & Waste Management Association Flue Gas Desulfurization: The State of the Art
R.K. Srivastava
Office of Research and Development, National Risk Management Research Laboratory,
Air Pollution Prevention and Control Division, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina
W. Jozewicz
ARCADIS Geraghty & Miller, Inc., Research Triangle Park, North Carolina ABSTRACT
Coal-fired electricity-generating plants may use SO2 scrubbers to meet the requirements of Phase II of the Acid Rain
SO2 Reduction Program. Additionally, the use of scrubbers can result in reduction of Hg and other emissions
from combustion sources. It is timely, therefore, to examine the current status of SO2 scrubbing technologies. This
paper presents a comprehensive review of the state of the
art in flue gas desulfurization (FGD) technologies for coalfired boilers.
Data on worldwide FGD applications reveal that wet
FGD technologies, and specifically wet limestone FGD,
have been predominantly selected over other FGD technologies. However, lime spray drying (LSD) is being used
at the majority of the plants employing dry FGD technologies. Additional review of the U.S. FGD technology
applications that began operation in 1991 through 1995
reveals that FGD processes of choice recently in the United
States have been wet limestone FGD, magnesiumenhanced lime (MEL), and LSD. Further, of the wet limestone processes, limestone forced oxidation (LSFO) has
been used most often in recent applications.
The SO2 removal performance of scrubbers has been
reviewed. Data reflect that most wet limestone and LSD
installations appear to be capable of ~90% SO2 removal.
Advanced, state-of-the-art wet scrubbers can provide SO2
removal in excess of 95%. IMPLICATIONS
Coal-fired power plants may use SO2 scrubbers to meet
the requirements of Phase II of the Acid Rain SO2 Reduction Program. Additionally, the use of scrubbers can
result in reduction of Hg and other emissions from combustion sources. This paper presents a comprehensive
review of the state of the art in FGD technologies for
coal-fired boilers. 1676 Journal of the Air & Waste Management Association Costs associated with state-of-the-art applications of
LSFO, MEL, and LSD technologies have been analyzed
with appropriate cost models. Analyses indicate that the
capital cost of an LSD system is lower than those of same
capacity LSFO and MEL systems, reflective of the relatively
less complex hardware used in LSD. Analyses also reflect
that, based on total annualized cost and SO2 removal requirements: (1) plants up to ~250 MWe in size and firing
low- to medium-sulfur coals (i.e., coals with a sulfur content of 2% or lower) may use LSD; and (2) plants larger
than 250 MWe and firing medium- to high-sulfur coals
(i.e., coals with a sulfur content of 2% or higher) may use
either LSFO or MEL.
INTRODUCTION
SO2 emissions are known to cause detrimental impacts
on human health and the environment. The major health
concerns associated with exposure to high ambient concentrations of SO2 include breathing difficulty, respiratory illness, and aggravation of existing cardiovascular
disease. In addition to the health impacts, SO2 leads to
acid deposition in the environment. This deposition
causes acidification of lakes and streams and damage to
tree foliage and agricultural crops. Furthermore, acid deposition accelerates the deterioration of buildings and monuments. While airborne, SO2 and its particulate matter (PM)
derivatives contribute to visibility degradation.
Combustion of sulfur-containing fuels, such as coal
and oil, results in SO2 formation. Electricity-generating
plants account for the majority of SO2 emissions in the
United States. The Acid Rain SO2 Reduction Program, established under Title IV of the Clean Air Act Amendments
of 1990, was designed to reduce SO2 emissions from the
power-generating industry. Phase I of this program began
on January 1, 1995, and ended on December 31, 1999. In
1997, 423 electricity-generating units, affected under
Phase I, emitted 5.4 million tons (4903.2 × 106 kg) of SO2
compared with the allowable 7.1 million tons (6446.8 ×
Volume 51 December 2001 Srivastava and Jozewicz
106 kg).1 Thus, the SO2 emissions in 1997 were 23% below
the allowable amount. Phase II of the Acid Rain SO2 Reduction Program began on January 1, 2000. To meet the
requirements of this phase, some power plants may use
flue gas desulfurization (FGD) technologies. Additional
environmental benefits that may result from the use of
these technologies are synergistic reductions in Hg emissions, as well as reductions in fine PM concentrations in
the atmosphere. It is timely, therefore, to examine the
current status of FGD (or SO2 scrubbing) technologies
applicable to electricity-generating plants.
The review of FGD technologies presented in this
paper describes these technologies, assesses their applications, and characterizes their performance. Then, the paper presents an analysis of the costs associated with
limestone forced oxidation (LSFO), lime spray drying
(LSD), and magnesium-enhanced lime (MEL) FGD technology applications. It is expected that this review will be
useful to a broad audience, including individuals responsible for developing and implementing SO2 control strategies at sources, persons involved in developing SO2 and
other regulations, state regulatory authorities implementing SO2 control programs, and the interested public at
large. Persons engaged in research and development efforts aimed at improving cost-effectiveness of FGD technologies may also benefit from this review.
CLASSIFICATION OF FGD TECHNOLOGIES
Various technologies exist to remove SO2 from flue gas
produced by electricity-generating plants. Existing FGD
technologies were comprehensively evaluated by the Electric Power Research Institute in their review report.2 The
technologies discussed in this report represent a broad
spectrum of maturity. Some can claim tens of thousands
of hours of commercial operating experience, while others have been tested only at pilot-scale. A compendium
of FGD technology applications is provided in the
CoalPower3 database, available from the International
Energy Agency’s Clean Coal Centre in London.3
Conventionally, FGD processes can be classified as
once-through or regenerable, depending on how the sorbent is treated after it has sorbed SO2. In once-through
technologies, the spent sorbent is disposed of as a waste
or utilized as a byproduct. In regenerable technologies,
SO2 is released from the sorbent during the sorbent’s regeneration, and the SO2 may be further processed to yield
H2SO4, elemental sulfur, or liquid SO2. No waste is produced in regenerable technology applications. Both oncethrough and regenerable technologies can be further
classified as either wet or dry. In wet processes, wet slurry
waste or byproduct is produced, and the flue gas leaving
the absorber is saturated with water. In dry processes,
dry waste material or byproduct is produced, and the
Volume 51 December 2001 flue gas leaving the absorber is not saturated. The classification of FGD processes is shown in Figure 1.
At present, regenerable FGD technologies are being
used only marginally in the United States and abroad, as
evident from Table 1.3 This may be because these processes
involve relatively higher costs compared with other FGD
processes. For example, capital costs for FGD technology
application on a new 300-MWe plant burning 2.6% sulfur
coal were estimated at 170 and 217 $/kW for wet oncethrough FGD and sodium sulfite regenerable processes,
respectively.2 Considering the relatively marginal application of regenerable FGD processes, this paper focuses only
on once-through FGD processes. Accordingly, when wet
FGD is mentioned in the remainder of this paper, it is meant
to be once-through wet FGD. Similarly, when dry FGD is
mentioned, it is meant to be once-through dry FGD.
DESCRIPTION OF ONCE-THROUGH PROCESSES
In once-through technologies, the SO2 is permanently
bound in the sorbent, which must be disposed of as a
waste or utilized as a byproduct (e.g., gypsum). This section presents the FGD processes reported in literature2 and
in an International Energy Agency database of commercial applications.3 For each process, typical SO2 reduction,
advantages, and any constraints are described.
Once-Through Wet FGD Technologies
In these technologies, SO2-containing flue gas contacts
alkaline aqueous slurry in an absorber. The slurry is generally made from either lime [typically 90% or more
Ca(OH)2] or limestone (typically 90% or more CaCO3).
The most often used absorber application is the countercurrent vertically oriented spray tower. A generic layout
of a limestone-based wet FGD process is shown schematically in Figure 2.
In the absorber, SO2 dissolves in the slurry and initiates the reaction with dissolved alkaline particles. The
absorber slurry effluent, containing dissolved SO2, is held
in a reaction tank, which provides the retention time for
finely ground lime or limestone particles in the slurry to Figure 1. Classification of FGD processes.
Journal of the Air & Waste Management Association 1677 Srivastava and Jozewicz
Table 1. Generating capacity (MW ) equipped with FGD technology through 1998.
e Technology United States Abroad World Wet
Dry
Regenerable
Total FGD 82,092
14,081
2798
98,971 114,800
10,654
2394
127,848 196,892
24,735
5192
226,819 dissolve and to complete the reaction with the dissolved
SO2. As a result of this reaction, sulfite/sulfate crystallization occurs in the reaction tank, and alkalinity of the slurry
is depleted. Fresh slurry is added to the reaction tank to
compensate for this depletion and thereby maintain a
desired level of alkalinity. The slurry is recirculated from
the reaction tank into the absorber. Reaction products
from the reaction tank are pumped to the waste-handling
equipment, which concentrates the waste. From the wastehandling equipment, the concentrated waste is sent for
disposal (ponding or stacking) or, alternatively, processed
to produce a salable gypsum (calcium sulfate dihydrate)
byproduct. The practical wet FGD processes are described
in the following sections.
Limestone Forced Oxidation. Over the years, LSFO, which
minimizes scaling problems in the absorber, has become
the preferred wet FGD technology process. Gypsum scale
typically forms via natural oxidation when the fraction
of CaSO4 in the slurry (slurry oxidation level) is greater
than 15%. In LSFO, scaling is prevented by forcing oxidation of CaSO3 to CaSO4 by blowing air into the reaction
tank (in situ oxidation) or into an additional hold tank
(ex situ oxidation).4 The gypsum thus formed is removed
as usual and, as a consequence, the concentration of gypsum in the slurry recycled to the absorber decreases.
The LSFO process can remove in excess of 95% of
SO2. The prime benefit of scale control derived from forced Figure 2. Wet FGD processes.
1678 Journal of the Air & Waste Management Association oxidation is greater scrubber absorber availability. As a
result, the need for redundant capacity is greatly reduced.
Additional benefits are formation of a stable product,
the potential for elimination of landfilling, and smaller
dewatering equipment. Further, depending on site-specific conditions, LSFO may produce a salable byproduct
in the form of commercial-grade gypsum that could be
used for wallboard manufacturing. When salable gypsum is not attainable, dry FGD waste is piled (gypsum
stacking) or landfilled. The operation of the LSFO process can be improved when organic acids, such as dibasic acid, are added to the limestone slurry. The use of
organic acid buffering allows for a smaller absorber and
increased sorbent utilization.
Variations in LSFO process design include a cocurrent,
downflow absorber with a single level of grid packing.
The cocurrent contact of slurry and flue gas allows for a
higher flue gas velocity and results in a reduced pressure
drop. Additionally, combining the cocurrent absorber
tower and reaction tank can reduce space requirements.
In this design, limestone slurry is sprayed above the grid
and is contacted by the flue gas. Simultaneous forced oxidation and agitation in the reaction tank is accomplished
with a rotating air sparger. This sparger prevents solids
from settling out in the reaction tank and provides nearly
complete oxidation of CaSO3 to CaSO4.
Another variation in LSFO design includes contacting flue gas with dilute slurry in a double-loop recycle
system. Approximately 25–30% of the SO2 in the flue gas
reacts with the recycle slurry of CaSO4 and CaCO3 in the
lower, first stage of the absorber. The flue gas then flows
upward to the second stage, where the remaining SO2 is
contacted with dilute slurry of CaSO3, CaSO4, and CaCO3
in the second recycle loop. The CaSO3 reaction product
slurry from the second loop drains to the lower first loop
of the absorber, where it is oxidized to CaSO4. Minimal
addition of fresh CaCO3 to a lower loop helps decrease
pH and promote CaSO3 oxidation.
Limestone Inhibited Oxidation. Another wet limestone process designed to control oxidation in the absorber is limestone inhibited oxidation (LSIO), in which emulsified
sodium thiosulfate is added to the limestone slurry feed
to prevent the oxidation of CaSO3 to gypsum in the absorber by lowering the slurry oxidation level to less than
15%. Because of economic considerations, sulfur is often added to the limestone slurry in lieu of thiosulfate.
Sulfur is added directly to the limestone reagent tank,
and conversion to thiosulfate occurs when sulfur contacts sulfite in the reaction tank. The overall conversion
of sulfur to thiosulfate is between 50 and 75%. The
amount of thiosulfate (or sulfur) required to achieve inhibited oxidation is a function of system chemistry and
Volume 51 December 2001 Srivastava and Jozewicz
operating conditions. The LSIO chemistry is particularly
efficient in applications with high-sulfur coals,5 because
the difficulty in inhibiting the oxidation generally increases with decreasing sulfur content in coal.
In some instances, LSIO may be economically preferred over LSFO when a salable gypsum byproduct is not
required. This is because LSIO does not require the use of
air compressors, as does LSFO. An additional benefit of
using LSIO may be increased limestone solubility, which
enhances sorbent utilization. However, in general, solids
dewatering is more difficult in LSIO compared with LSFO
due to a higher level of sulfites. The waste product, CaSO3,
resulting from the LSIO process is landfilled. Note that
the LSIO waste has improved dewatering characteristics
compared with the waste from natural oxidation operation of a wet FGD absorber. This is because the CaSO3
product from the LSIO tends to form larger crystals, similar to gypsum solids.
Jet Bubbling Reactor. The jet bubbling reactor (JBR) process represents a different approach to gas/liquid contacting for SO2 removal than does LSFO or LSIO. In JBR, SO2
absorption, sulfite/bisulfite oxidation, and precipitation
of gypsum are accomplished in a single reaction vessel.
The contact is achieved by injecting flue gas through gas
sparger tubes immersed below the surface of the limestone
scrubbing slurry. The so-called “jet bubbling zone” is
formed, in which the flue gas vigorously bubbles through
the surrounding liquid, thus creating a large gas/liquid
interfacial area for SO2 absorption.6 In this zone, maintained at a slightly lower pH than that for LSFO (3.5–4.5
compared with 5.5–6.5) to increase reaction rates and prevent sulfite and carbonate scale formation, neutralization
and oxidation of bisulfites and formation of gypsum crystals occur. The lower pH allows the JBR to attain essentially 100% utilization of limestone.
The overall chemical reactions in the JBR are similar
to those occurring in the LSFO. However, the intermediate reaction compound is a nonscaling bisulfite instead
of the scale-producing sulfite. As a result, JBR produces
gypsum crystals, which are larger and dewater better than
gypsum crystals from LSFO. The total system pressure drop
is greater than most conventional spray tower LSFOs.
However, the JBR design allows elimination of highenergy-demand slurry spray pumps.
Lime and Magnesium-Enhanced Lime. The lime process uses
hydrated calcitic lime slurry in a spray tower, which predominantly is countercurrent flow. Because this slurry is
more reactive than limestone slurry, the absorber designed
for lime sorbent is generally smaller compared with one
designed for limestone slurry. However, lime sorbent is
more expensive than limestone sorbent.
Volume 51 December 2001 The MEL process is a variation of the lime process in
that it uses a special type of lime that contains magnesium in addition to its calcitic component. Because of the
greater solubility of magnesium salts compared with calcitic sorbents, the scrubbing liquor is significantly more
alkaline. Therefore, MEL is able to achieve high SO2 removal efficiencies in significantly smaller absorber towers than its calcitic lime sorbent counterparts. Additionally,
less MEL slurry is needed compared with LSFO for the
same level of SO2 removal. Also, because of the lower liquid recirculation requirement, pumps are smaller, and the
scrubber-gas-side pressure drop is lower in an MEL system than in a comparable LSFO system. For these and
other reasons, process energy requirements are lower in
MEL compared with those needed in LSFO. Furthermore,
gypsum produced from the MEL process may be lighter
in color than that produced by LSFO. If desired, Mg(OH)2
byproduct can also be produced from the MEL process.7
Mg(OH)2 is an alkaline reagent, which can be used to reduce SO3 emissions and also to treat plant liquid effluents
prior to discharge.
Dual Alkali. This process utilizes two alkaline materials: a
sodium solution for scrubbing and lime for treatment of
the scrubbing solution. A sodium sulfite solution is sprayed
into an open spray tower to remove SO2 from the flue
gas. Lime is added to the product solution in an external
tank to recover the sodium solution and form a CaSO3rich sludge. Because the absorption step uses a soluble
alkali, the dissolution rate of the reagent is not the ratelimiting step as it is in LSFO. Consequently, lower liquid/
gas (L/G) ratios are used in the dual alkali process compared with those used in LSFO.
The dual alkali process produces CaSO3/CaSO4 sludge.
This sludge must be disposed of in a lined landfill because of sodium scrubbing solution losses to the product
material and the resulting sodium salt concentration in
the filter cake. Scrubbing solution losses may be decreased
by improved filter cake washing techniques.
In a variation of the dual alkali process, limestone
may be added to a slipstream from an open spray tower
removing SO2. Limestone simultaneously recovers sodium
sulfite and forms sludge rich in CaSO3. Similarly to the
requirements for the lime-based dual alkali process, a lined
landfill may be required because of the soluble sodium
salts entrained in the solid product. Additionally, these
solids must be fixated with lime and fly ash.
The Seawater Process. This process utilizes the natural alkalinity of seawater to neutralize SO2. The chemistry of
the process is similar to that of LSFO, except it does not
involve any dissolution or precipitation of solids. Seawater may be available in large amounts at the power plant
Journal of the Air & Waste Management Association 1679 Srivastava and Jozewicz
as a cooling medium in the condensers. It then can be
used as a sorbent downstream of the condensers for the
purpose of FGD. Seawater is alkaline by nature, and has a
large neutralizing capacity with respect to SO2.
The absorption of SO2 takes place in an absorber, where
seawater and flue gas are brought into close contact in a
countercurrent flow. The scrubber effluent flows to the treatment plant, where it is air-sparged to oxidize absorbed SO2
into sulfate before discharge.8 Since sulfate is completely
dissolved in seawater, it does not result in any waste product that would require disposal. Sulfate is a natural ingredient in seawater, and typically there is only a slight increase
in its concentration in the discharge. This increase is within
the variation naturally occurring in seawater. The difference from the background level is normally not detectable
within even a short distance from the point of discharge.
Because the utilization of seawater for SO2 scrubbing
introduces a discharge to the ocean, it is necessary to make
an assessment based on local conditions. Typically, this assessment includes effluent dilution and dispersion calculations, a description of the effluent, a comparison of effluent
data with local quality criteria, a description of the local
marine environment, and evaluation of possible effects from
the discharge. High chloride concentrations, characteristic
of systems using seawater, result in a requirement for construction materials with increased corrosion resistance.9
Once-Through Dry FGD Technologies
In these technologies, SO2-containing flue gas contacts alkaline (most often lime) sorbent. As a result, dry waste is
produced, which is generally easier to dispose of than waste
produced from wet FGD processes. The sorbent can be delivered to the flue gas in an aqueous slurry form (LSD) or as
a dry powder [furnace sorbent injection (FSI), LIFAC process
(LIFAC), economizer sorbent injection (ESI), duct sorbent
injection (DSI), duct spray drying (DSD), circulating fluidized bed (CFB), or Hypas sorbent injection (HSI)]. LSD and
CFB require dedicated absorber vessels for sorbent to react
with SO2, while in DSI and FSI, new hardware requirements
are limited to sorbent delivery equipment. In dry processes,
sorbent recirculation may be used to increase its utilization.
A schematic of dry FGD processes involving dry powder injection and DSD is shown in Figure 3. In this figure, the flue
gas flow for a plant without FGD is shown with the solid
line. Sorbent injection locations for alternative dry FGD processes with dry powder injection or DSD are shown schematically with broken lines. These processes are discussed
in the following sections.
Lime Spray Drying. This process is most often used by
sources that burn low- to medium-sulfur coal. The schematic of LSD is shown in Figure 4. Rotary atomizers or
two-fluid nozzles are used to finely disperse lime slurry
1680 Journal of the Air & Waste Management Association Figure 3. Sorbent injection processes. into the flue gas. Hot flue gas mixes in a spray dryer vessel with a mist of finely atomized fresh lime slurry. Simultaneous heat and mass transfer between alkali in the finely
dispersed lime slurry and SO2 from the gas phase results
in a series of reactions and a drying of reacted products. A
close approach to adiabatic saturation (from 10 to 15 ºC
for coal-derived flue gas) is required to achieve high SO2
removal. However, complete saturation can impair operation of a spray dryer because of wet solids adhering to
vessel walls, to gas flow passages from the vessel, and in
the particulate collector.10 Therefore, the water content
of the slurry fed into the spray dryer is carefully controlled
to avoid complete saturation of the flue gas.
Studies indicate that most SO2 capture in the spray
dryer occurs when the sorbent is still moist. Therefore,
deliquescent additives may be used to increase the duration of time in which the sorbent remains moist. A similar effect is achieved when spray dryers are used on coals
with elevated chloride content. However, the addition of
deliquescent materials needs to be closely controlled to
avoid the wet solids problem noted previously.
Furnace Sorbent Injection. In FSI, dry sorbent is injected
directly into the section of the furnace where temperatures
are between 950 and 1000 ºC. Sorbent particles (most
often hydrated lime, sometimes limestone) decompose
and...
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Optimal Deployment of Emissions Reduction Technologies for Construction Equipment.pdf
TECHNICAL PAPER ISSN:1047-3289 J. Air & Waste Manage. Assoc. 61:611– 630
DOI:10.3155/1047-3289.61.6.611
Copyright 2011 Air & Waste Management Association Optimal Deployment of Emissions Reduction Technologies
for Construction Equipment
Muhammad Ehsanul Bari
Zachry Department of Civil Engineering, Texas A&M University, College Station, TX O tho
T r'
D sP
is
tri er
bu so
te na
or l C
R op
ep y
ro
du
ce Josias Zietsman
Texas Transportation Institute, The Texas A&M University System, College Station, TX
Luca Quadrifoglio
Zachry Department of Civil Engineering, Texas A&M University, College Station, TX Mohamadreza Farzaneh
Texas Transportation Institute, The Texas A&M University System, College Station, TX N Au ABSTRACT
The objective of this research was to develop a multiobjective optimization model to deploy emissions reduction
technologies for nonroad construction equipment to reduce emissions in a cost-effective and optimal manner.
Given a fleet of construction equipment emitting different pollutants in the nonattainment (NA) and near
-nonattainment (NNA) counties of a state and a set of
emissions reduction technologies available for installation on equipment to control pollution/emissions, the
model assists in determining the mix of technologies to
be deployed so that maximum emissions reduction and
fuel savings are achieved within a given budget. Three
technologies considered for emissions reduction were designated as X, Y, and Z to keep the model formulation
general so that it can be applied for any other set of
technologies. Two alternative methods of deploying these
technologies on a fleet of equipment were investigated
with the methods differing in the technology deployment
preference in the NA and NNA counties. The model having a weighted objective function containing emissions
reduction benefits and fuel-saving benefits was programmed with C⫹⫹ and ILOG-CPLEX. For demonstration purposes, the model was applied for a selected construction equipment fleet owned by the Texas Department of D O IMPLICATIONS
This paper describes a model that was developed to help
decision-makers/fleet managers deploy emissions reduction technologies to maximize the benefit of emissions reductions and fuel savings from their construction equipment fleet. The model is based on a cost-effectiveness
analysis. The model was demonstrated with three different
emissions reduction technologies having different operational and performance characteristics. The model structure is quite flexible and thus can be adapted and applied to
any type of emissions reduction technologies and can be
implemented on on-road and nonroad sources. Volume 61 June 2011 Transportation, located in NA and NNA counties of Texas,
assuming the three emissions reduction technologies X,
Y, and Z to represent, respectively, hydrogen enrichment,
selective catalytic reduction, and fuel additive technologies. Model solutions were obtained for varying budget
amounts to test the sensitivity of emissions reductions
and fuel-savings benefits with increasing the budget. Different mixes of technologies producing maximum oxides
of nitrogen (NOx) reductions and total combined benefits
(emissions reductions plus fuel savings) were indicated at
different budget ranges. The initial steep portion of the
plots for NOx reductions and total combined benefits
against budgets for different combinations of emissions
reduction technologies indicated a high benefit-cost ratio
at lower budget amounts. The rate of NOx reductions and
the increase of combined benefits decreased with increasing the budget, and with the budget exceeding certain
limits neither further NOx reductions nor increased combined benefits were observed. Finally, the Pareto front
obtained would enable the decision-maker to achieve a
noninferior optimal combination of total NOx reductions
and fuel-savings benefits for a given budget. INTRODUCTION
Pollutant emissions are a serious concern for human
health and for the environment1 because they can cause a
range of problems to the human body (including death)
and damage to trees, crops, plants, lakes, and animals.
The U.S. Environmental Protection Agency (EPA) categorized air pollution sources as stationary and mobile. Stationary sources include facilities such as oil refineries,
chemical processing facilities, power plants, and other
manufacturing facilities. There are federal and state air
pollution control requirements for most stationary
sources.2 Mobile sources are divided into two groups: onroad and nonroad. According to EPA, on-road sources are
vehicles used on roads for movement of passengers or
freight. They include light-duty vehicles, light-duty Journal of the Air & Waste Management Association 611 Bari et al.
from the construction equipment fleet as an important
component of an emissions control strategy.8
Various emissions reduction technologies are used to
control emissions from on-road and off-road equipment
in the United States. Reduced emissions is a benefit to
society through improved health and to public agencies
through reaching conformity, compliance, and attainment. However, purchasing these emissions reduction
technologies is a cost to the concerned agency. Thus, it is
essential for an agency to utilize their budget to install the
emissions reduction technologies in a cost-effective and
optimal manner, and no model has yet been developed
for this purpose.
Therefore, the purpose of this study was to develop a
multiobjective optimization model for optimal deployment of emissions control technologies to maximize the
benefit from emissions reductions and fuel savings from
nonroad construction equipment located in nonattainment (NA) and near-nonattainment (NNA) counties. NA
counties are those that failed to meet federal standards for
ambient air quality, and the NNA counties are those that
are at risk of violating standards although these areas
currently meet federal standards.9 The model will aid the
decision-maker or fleet manager to quickly decide how to
choose the most appropriate emission reduction technology to be deployed and maximize the overall benefit. D O N Au O tho
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ce trucks, heavy-duty vehicles, medium-duty passenger vehicles, and motorcycles. Nonroad sources consist of engines, aircraft, marine vessels, locomotives, and equipment used for construction, agriculture, transportation,
and recreational purposes.3
On-road and nonroad diesel engines are responsible
for emitting harmful pollutants, such as nitrogen oxides
(NOx) and particulate matter (PM). On the basis of EPA’s
1999 report regarding national NOx emissions, on-road
and nonroad sources contributed 34 and 22% of the nation’s total NOx emissions, respectively. Among the nonroad sources, diesel equipment emitted 49% of NOx. Fine
particulate matter (PM2.5) emissions for on-road and nonroad sources were 10 and 18% of the nation’s total PM2.5
emissions, respectively, and among the nonroad sources,
diesel equipment contributed 57% of PM2.5.3 These facts
indicate that NOx and PM2.5 emissions from the nonroad
sector, especially diesel equipment, are very significant,
causing air pollution and health-related problems.4
Diesel exhaust is considered a probable human
carcinogen. According to EPA, emissions from nonroad
sources will continue to increase and contribute large
amounts of PM and NOx. EPA’s data from 2005 indicated
that nonroad engines contributed approximately 66% of
the nation’s PM2.5 from all mobile sources. These nonroad engine emissions affected approximately 88 million
Americans living in areas violating PM2.5 air quality standards. Similarly, NOx and volatile organic compound
(VOC) emissions from nonroad engines were approximately 36 and 37%, respectively, from all mobile sources.
These two pollutants affected approximately 159 million
Americans living in areas exceeding EPA’s 8-hr ozone
standard.5
EPA’s 2008 National Emissions Inventory (NEI) data
show that the total national NOx emissions from on-road
and nonroad sources were 4,675,896 and 1,884,943 t,
respectively. The same NEI data also indicate that the
nonroad sources emitted approximately 29% of the total
NOx emissions from the mobile sources. The share of
diesel equipment was approximately 74% of NOx among
the nonroad sources. Similarly, the total PM2.5 emissions
from the on-road and nonroad sources were 269,454 and
116,752 t, respectively. The nonroad sources contributed
approximately 66% of the total PM2.5 emissions from the
mobile sources, and among the nonroad sources diesel
equipment contributed approximately 66% of PM2.5
emissions.6
Construction equipment is a sector of nonroad
sources. The construction industry uses more than 2 million pieces of nonroad diesel construction equipment.
Most of the equipment has a long operational life—more
than 25–30 yr. A report from the Clean Air Act Advisory
Committee indicates that construction equipment contributed 32% of all mobile-source NOx emissions and 37%
of PM emissions. Nonroad equipment, having less stringent emissions standards, emits more pollution than
heavy-duty highway vehicles.7 Although stringent emissions standards were established for new nonroad equipment in 2008, most of the nonroad diesel equipment in
use before 2008 will operate for many more years before
retirement. EPA realized the issue with the construction
equipment fleet and considered the emissions reductions
612 Journal of the Air & Waste Management Association LITERATURE REVIEW
In this section, emissions estimation methodologies based
on EPA’s guidelines and procedures will be discussed. Different emissions reduction strategies such as aftertreatment devices, engine technologies, and fuel technologies will be briefly presented. At the end of this section,
several studies incorporating optimal allocation and
configuration will be discussed. Emissions Estimation Methodology
EPA developed the NONROAD model for estimating pollutant emissions such as carbon dioxide (CO2), carbon
monoxide (CO), hydrocarbon, NOx, and PM from compression-ignition engines. For calculating emissions from
construction equipment fleets, information on the zerohour steady-state emissions factors (EFss), transient adjustment factors (TAF), and deterioration factors (DF) are
required. After obtaining the values for EFss, TAF, and DF,
the final emissions factor (EFadj in g/hp-hr) for each pollutant can be calculated. The construction equipment
emissions are then calculated from the adjusted emissions
factor with the information on horsepower and usage
hours using eq 1.10
Emissions E共g兲 ⫽ EFadj ⫻ horsepower ⫻ usage hours (1) Abolhasani et al.11 compared the average emissions rates
estimated from portable emissions measurement system
(PEMS) data to estimates inferred from the NONROAD
model. They developed and demonstrated a study design
for deployment of a PEMS unit for excavators. They found
that the PEMS-based emissions factors were similar in
magnitude and were approximately comparable to those
Volume 61 June 2011 Bari et al.
from the NONROAD model. They demonstrated the importance of considering intercycle variability in realworld in-use emissions to develop more accurate emissions inventories. It is possible to improve nonroad
emissions factors and inventory models by considering
such factors as intervehicle and intercycle variability. O tho
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ce Emissions Reduction Options
Retrofit, rebuild, replace, and repower are some strategies
to reduce emissions from mobile sources. “Retrofit”
means installing an emissions control device on the
equipment, “rebuilding” is rebuilding some core engine
components of the equipment, “repowering” is replacing
the older diesel engines with a newer engine, and “replacing” is replacing the entire older equipment or vehicle.12
The Manufacturers of Emissions Controls Association
(MECA),13 Hansen,14 EPA,15 the California Air Resources
Board,16 Genesis Engineering, Inc., and Levelton Engineering, Ltd.,17 and Lee et al.18 provide descriptions of
some emissions reduction options that are briefly presented in Table 1. The emissions reduction options are
divided into three categories: (1) exhaust gas aftertreatment technologies, (2) engine technologies, and (3) fuel
technologies according to Hansen14 and Genesis Engineering, Inc., and Levelton Engineering, Ltd.17 To formulate effective and cost-efficient emissions
control strategies, it is essential to have a better understanding of the overall effect of emissions control strategies on chemically interrelated important atmospheric
pollutants. Luecken and Cimorelli19 used an air quality
model to observe the potential effect of three emissions
reductions on concentrations of ozone, PM2.5, and four
important hazardous air pollutants (e.g., formaldehyde,
acetaldehyde, acrolein, and benzene). Their simulations
indicated the difficulty in assessing the response of toxic
air pollutants to emissions reductions aimed at decreasing
criteria pollutants such as ozone and PM2.5. This type of
research can help air quality managers avoid strategies
that may improve one pollutant but degrade air quality
by increasing other pollutants.
Studies Involving Optimal Allocation and
Configuration
The studies described in this section involved multiobjective, mixed-integer programming, linear programming,
integer programming (IP), and mixed-integer nonlinear
programming. Chang and Wang20 developed and applied
a multiobjective mixed-integer programming model for
resolving the potential conflict between environmental Table 1. A brief description of several emissions reduction options.
Category Exhaust gas aftertreatment
technologies Example DOC Diesel particulate filter Engine technologies Au Fuel technologies Selective catalytic reduction
Lean NOx catalysts
Engine repower and rebuild
Exhaust gas recirculation Crankcase emissions control
Natural gas Biodiesel Fuel additive D O N Hydrogen Hydrogen enrichment Description Can reduce PM emissions, but the total NOx
emissions remain unchanged for DOC.
Physically traps diesel particulates and prevents their
release into the atmosphere and can reduce PM
emissions.
Capable of reducing NOx, PM, and HC emissions.
Capable of reducing NOx emissions.
Provides NOx and PM reduction benefits.
Involves recirculation of a portion an engines’ exhaust
gas into its combustion chambers. Reduces NOx
emissions, but increases PM, HC, and CO
emissions and causes a fuel economy penalty.
Capable of reducing PM emissions.
Reduces emissions and provides a potential operating
cost savings.
Derived from renewable sources such as vegetable
oil, animal fat, and cooking oil. Emits more NOx
emissions than off-road diesel engines. Compatible
for use with high-efficiency catalytic emissions–
reduction technology.
Has low energy density in the gaseous form. Hence,
if less expensive and liquefied hydrogen become
readily available, then it becomes practical for use
in the nonroad equipment sector.
Can reduce engine emissions and/or improve fuel
economy. Some manufacturers claim that their
products can reduce NOx, HC, PM, and/or CO
emissions and can decrease fuel consumption.
Some of the products might increase one or more
pollutant emissions while reducing other pollutant
emissions and increasing fuel efficiency.
HE systems create a better flame front in the engine
that helps reduce emissions. Can reduce NOx and
CO emissions and decrease fuel consumption. Notes: DOC ⫽ diesel oxidation catalysts.
Volume 61 June 2011 Journal of the Air & Waste Management Association 613 Bari et al. D O N Au O tho
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ce and economic goals and for evaluating sustainable strategies for waste management in a metropolitan region.
They considered four objectives: economics, noise control, air pollution control, and traffic congestion limitations. The constraint set consisted of mass balance, capacity
limitations, operation, site availability, traffic congestion, financial, and related environmental quality constraints. They
performed a case study in the city of Kaohsiung in Taiwan.
Nema and Gupta21 formulated a multiobjective IP
model to obtain the optimal configuration of a hazardous
waste management system for transportation, treatment,
and disposal of hazardous waste at a minimum cost and
imposing minimum risk to the environment. The objectives addressed were minimization of cost, minimization
of risk, and minimization of a composite objective function consisting of cost and risk. The constraints consisted
of mass balance of waste, allowable capacities for treatment and disposal technologies, and constraints related
to waste-waste and waste-technology compatibility. An
illustrative case example was performed to demonstrate
the model’s usefulness.
Eshwar and Kumar22 used linear programming with
fuzzy coefficients for optimal deployment of construction
equipment. The objective was to identify the exact
amount of equipment to be bought or rented to complete
the project in the targeted period. The required minimum
number of each type of equipment, the cost and the rent
of equipment, the amount of equipment that could be
hired, and the duration of service were considered as
constraints. The model was able to optimally deploy
equipment and was capable of successfully handling the
uncertainty.
Swersey and Thakur23 developed an IP model for locating vehicle emissions testing stations. The constraints
used were maximum travel distance from each town to its
nearest station, average waiting time at the station, maximum hours of operations, and maximum number of
lanes at each station. The station configuration that was
in use had more stations than IP solutions. The IP model
was able to reduce the estimated cost of the objective
function by at least $3 million.
Mastsukura et al.24 proposed a mixed-integer model
to minimize CO2 emissions through determining the optimal set of ship routes and fleet of ships. Ship capacity
and maximum transportation time were considered as
constraints in the model. A case study was performed at
the Kobe port of Japan.
Sirikitputtisak et al.25 developed a mixed-integer nonlinear programming model for a multiperiod optimal energy planning program. The objective function included
the minimization of overall electricity costs and meeting
the projected electricity demand over a span of 14 yr.
Construction time, fluctuation of fuel prices, and CO2
emissions reduction target were included in the constraints set. The program that was developed can be extended to other states, provinces, or even countries.
MODEL FORMULATION
Figure 1 shows a flowchart of the overall approach that
involves several steps ranging from development of the
model to proposing a deployment plan of emissions control technologies. This model, which incorporates net
614 Journal of the Air & Waste Management Association Figure 1. Flowchart of the overall approach. present worth of benefits and costs, is an improved version of the model formulated by Bari.26 The process begins with conceptualizing the model through incorporating the objectives, constrains, and required data. The
subsequent steps are testing and refinement of the model.
The final step is the output of the model that will provide
a deployment plan prescribing a mix of emissions reduction technologies for deployment.
The objective of this optimization model is to maximize the emissions reduction and fuel savings for a given
nonroad construction equipment fleet. The constraint set
consists of relevant economic, operational, and technical
constraints. Table 2 summarizes the definition of the major variables used in the model. The set C is defined as the
set containing the NA and NNA counties, indexed by c.
The set nc is the total number of counties in consideration. The set E is the set of different categories of construction equipment indexed by e, and the set ne is the
total categories of construction equipment for consideration. The set nce is the total number of equipment of
category e located in county c, and each piece of equipment is indexed by i. Set P represents the set of different
pollutants indexed by p, and np denotes the total number
of pollutants to consider.
Set T represents the set of emissions reduction technologies indexed by t, and nt is the total number of
emissions control technologies to consider. Em denotes Volume 61 June 2011 Bari et al.
Table 2. Nomenclature of the variables used in the model. ␤ c,e,i ⫽ Definition C
nc
E
ne
nc,e
P
np
T
nt
Em
Cp
Rp,t
I
AP
Fc,e,i.
CF
FEt
Ct
Comc,e,i,t Set of NA and NNA counties
Total number of counties
Set of different categories of construction equipment
Total categories of construction equipment
Total number of equipment of category e in county c
Set of different pollutants
Total number of pollutants
Set of emissions reduction technologies
Total number of emissions reduction technologies
Emissions from a piece of equipment
Cost of pollutant p
Emissions reduction efficiency of technology t for pollutant p
Binary variable
Set of analysis periods for each piece of equipment
Fuel consumption of a piece of equipment
Cost of fuel per gallon
Fuel efficiency of technology t
Cost associated with technology t
Operation and maintenance costs of technology t for each
piece of equipment
Remaining usage hours of a piece of equipment
Expected usage hours of a piece of equipment
Remaining age of a piece of equipment
Expected age of a piece of equipment 冎 共1 ⫹ r兲␣c,e,i ⫺ 1
r共1 ⫹ r兲␣c,e,i (3) The fuel consumption of a piece of equipment is denoted
by Fc,e,i, the fuel efficiency of technology t is FEt, and the
cost of fuel per gallon is CF. If the technology selected
causes a fuel penalty, then the value of FEt will be negative. Therefore, the expression for fuel savings is Fc,e,iCFFEtIc,e,i,t. The final expression of the present worth value
of the total fuel savings over a period of ␣c,e,i for each
piece of equipment is O tho
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Ue,i
rac,e,i
Ae,i ⌺ ␣ 僆 AP ⌺c 僆 C⌺ne e⫽ 1⌺in⫽c,e1⌺nt ⫽t 1共␤c,e,iFc,e,iCFFEtIc,e,i,t兲 Objective Function
Two objectives were considered: (1) maximization of
emissions reduction and (2) maximization of fuel savings.
The final expression of the weighted objective function
consisting of emissions reduction benefits and fuel savings is shown in eq 5.
Maximize Z ⫽ 冘 冘冘冘冘冘
ne D O N Au the emissions from a particular piece of equipment. Cp
represents the cost of the pollutant p, and Rpt is the
emissions reduction efficiency of technology t for pollutant p. The variable I represents a binary variable having a
value of 0 or 1. If a particular technology is selected for a
piece of equipment, then the value of I will be 1; otherwise it will be zero.
The set AP is the analysis period for each piece of equipment during which retrofit costs could be incurred or benefits received, and AP is indexed by ␣. For an equipment of
category e located in county c, the corresponding analysis
period would be ␣c,e,i. For the net present worth analysis, the
interest rate r was considered to be 3%.27 For simplicity, it
was assumed that the usage hour and fuel consumption for
each piece of equipment as well as operation and maintenance costs for each technology will remain constant for
each year within the analysis period.
Similarly, the benefits obtained from emissions reduction and fuel savings for each piece of equipment will
remain constant for each year within the analysis period.
The cost of emissions per pollutant p from the ith equipment of category e located in county c is Emc,e,i,pCp. If
technology t is applied on that particular piece of equipment, the emissions reduction benefit will then be
Emc,e,i,pCpRp,tIc,e,i,t. The final expression of the present
worth value of total emissions reductions over a period of
␣c,e,i for each piece of equipment is
⌺ ␣ 僆 AP ⌺c 僆 C⌺ne e⫽ 1⌺in⫽c,e1⌺pnp⫽ 1⌺nt ⫽t 1共Emc,e,i,pCpRp,tIc,e,i,t兲
⫻ 再 冎 共1 ⫹ r兲␣c,e,i ⫺ 1
r共1 ⫹ r兲␣c,e,i (2) Henceforth, the second factor of the above expression is
denoted by ␤c,e,i so that
Volume 61 June 2011 (4) W1 nc,e np nt 共␤c,e,iEmc,e,i,pCpRp,tIc,e,i,t兲 (5) ␣ 僆 AP c 僆 C e ⫽ 1 i ⫽ 1 p ⫽ 1 t ⫽ 1 冘 冘冘冘冘
ne ⫹ W2 nc,e nt 共␤c,e,iFc,e,iCFFEtIc,e,i,t兲 ␣ 僆 AP c 僆 C e ⫽ 1 i ⫽ 1 t ⫽ 1 In eq 5, W1 and W2 are the weights associated with the
emissions reduction benefits and the benefit from fuel
savings, respectively, such that W1 ⫹ W2 ⫽ 1. Note that
W1 and W2 can be assigned any values between 0 and 1
to represent the contribution of emissions reduction and
fuel saving benefits, respectively. Model Constraints
For formulation of constraints, information about the type
of emissions reduction technologies (e.g., retrofit, fuel additive, etc.) is necessary. For the model presented here, it is
assumed that three technologies (labeled as X, Y, and Z) are
available for use. Further, assume that X and Y corr...
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Pollution Prevention Practices in Oregon's Electronics Industry.pdf
PRES
Pollution Prevention Practices
in Oregon’s Electronics Industrv
I Cynthia L. Jones, M.S. and
Anna K. Harding, R.S., Ph.D. - NEHA members safer products thai work as well as current produits, ethical concerns, and long term
. financialbenefits. Common problems that discouraged the industry from changing to
. less
._hazardous
-practices included: (1) the new product did not hnction as well as the
original material; (2) the respondents did not believe current practices were harmful;
and, (3) initial costs were prohibitive. Representatives from within this industry are
, , Introduction
In 1990, Congress passed the Pollution
Prevention Act that mandated industries to
implement pollution prevention programs to
decrease theamount and toxicity ofhazardous
ptoducts used in production processes (1).
Pollution prevention reduces waste at the source, which decreases the cost of treatment,
and also eliminates the undesirable practice of
transferring pollution from one medium to
another. Pollutionpreventionstrengthenseconomic competitiveness by using raw materials
more efficiently; thus, it promotes economic growth while protecting the environment (2).
With the implementation of pollution prevention practices, some manufacturers have
attempted substituting less harmful chemicals
in the production process. Although these
substitutions are honest attempts at reducing
pollution, cases exist in which the substituted
chemical (which is advertised as being environmentally benign) is actually no less toxic
than the original material (3). For example,
Chlorofluorocarbons ( CFCs) were considered
safe for $0 years. Nontoxic, nonflammable,
and noncorrosive, they replaced hazardous
substances such as ammonia and sulfur dioxide. Scientists, however, discovered that CFCs
were not benign; rather, the chemicals were
rising into the atmosphere and insidiously
eating a hole in the earths protective ozone
layer (3). In addition, existing legislation does
not clearly define what criteria must be met to
label a product as “green”or “environmentally
friendly” (4).
On a nationwide basis, the electronics industry generates a large amoun‘t of hazardous
waste due to the use of solvents and heavy
metals in the manufacturing process (1).The
industry is characterized by the use of highly
toxic compounds that are routinely handled
by employees (5). For example, potentially
hazardous materials utilized by the semiconductor industry include dopant gases, photoresist solvents, organic solvents, and hydrofluoric acid (6). Two commonly used chemicals in the making of computer chips are
diethyleneglycoldimethylether(DIGLM) and JanuarylFebruary 1997 Environmental Health 21 L
2 i working at the facility. The reethylene glycol monoethgl ether
sponses indicated that 15 peracetate (ECA). These photorecent of the businesses employed
sist solvents have recently been
Factors that discourage organizations from
over 500 people, 33 percent
linked to miscarriages and other
employed 76-500 people, 20
reproductive problems in chip
switching to less hazardous products or processes
percent employed 21-75people,
factory workers (7,8).
25 percent employed 6-20
In Oregon, the electronics
people and only 8 percent of
industry has recently been identhe respondents represented
tified by the Oregon Departsmall companies of 1-5 employment of Environmental Quality
ees at the facility. As a whole,
(DEQ) as one of the top five
these companies manufacture
polluters in the state of Oregon
a wide variety of products, inwhen measured in pounds of
cluding circuit boards, cable
pollution produced (9). Despite
assemblies, printers, software,
the data suggesting that
temperature controls,. laser
Oregon’s electronics industry
equipment, and controlpanels.
produces large quantities ofhazThe majority of the businesses
ardous waste, little is known
participating in this research
about theindustry’s interest and/
were well-established; most
or involvement in switching to
have been in operation for over
less pollutingpractices. The purthree years.
pose of this study, therefore,
Fifty percent of the responwas to identify pollution predents revealed that their comvention strategies that are curpany recycles materials within
rently being used in the electhe
facility.
Participants
indicated that the
tronics industry of Oregon, and to assess the
distributed. Although this was considered to
products
which
were
most
likely to be reindustry’s interest in switching to less hazardbe a low response rate, we considered the
cycled
included
cardboard
(19
percent), office
ous practices.
response rate to be comparable to that of a
paper (18 percent), tidaluminum (13 perpollution prevention study conducted by reMethods
cent), newspaper (12percent), andusedchemisearchers who surveyed mid-sized organizaA survey querying pollution prevention
cals (11 percent).
tions (100-1000employees) that generate hazpractices was mailed to 180 electronics firms
Businesses were asked how often they upardous waste, in which “an amazing 40 perdated environmentalmanagement procedures.
in Oregon. These firms were selected from
cent responded” (10, p.13). Several reasons
The vast majority of responses (73 percent)
listings in Oregon phone directories and from
may account for this rate in our study. Responindicated environmental management procethe American Electronics Association memdents may have been reluctant to reveal any
dures were updated yearly. Eighteen percent
bership registry. Some firms were included in
information about new products that replace
updated environmental procedures every 2-4
both listings, so a final list of 192 businesses
hazardous products or procedures that are
years and 5 percent allowed eight or more
was compiled after cross-checking both lists
considered to be proprietary information. A
years to pass before addressing these proceand deleting duplicate businesses. The survey
second reason might be that although confidures. Only 4 percent of the respondents indiwas pilot tested with 12 of the 192 organizadentiality was assured, firms might have been
cated these procedures were never updated.
tions, which were chosen at random from the
worried that disclosing information about their
These results suggest that because the elecfinal list. Those in the pilot group were exenvironmental procedures might somehow
tronics industry is relatively new compared to
cluded from data analysis. No changes were
place them under greater scrutiny by state
other industries, procedures are probably upmade in the actual content of the questionregulatory agencies. A third reason might be
dated frequently as the industry quickly develnaire, but slight modifications were made in
that the survey never reached the person in the
ops and adapts to changes in environmental
the introductory letter as a result of the pilot
organization best able to answer the questions.
regulations.
study. The revised survey, cover letter, and
We found that the specific title for individuals
self-addressed stamped return envelope was
Hazardous materials production
responsible for environmental management
mailed as a unit to the safety engineer or
To obtain a better understanding of the
varied considerably among these organizamanager of the remaining 180 businesses on
point in the processing stages in which hazardtions.
the list. Respondents were asked to return the
ous materials are more likely to be produced,
The data were described using mean values,
completed survey within two weeks, and a
the following question was asked, “In your
frequency distributions, and percentages.
follow-up postcard was mailed to those firms
opinion, at your facility, where in the lifecycle
Microsoft Windows Excel Program Version 5.0
not responding by the given deadline.
of the manufacturing process is the largest
wasutilized forgraphic presentation of thedata.
Responses were obtained from 75 (42 perquantity of hazardous materials generated?”
cent) of the 180 organizations. Of these,
The majority reported that the largest quantity
Results and Discussion
7 percent returned the survey but declined to
of hazardous materials was generated early on
Industry demographics
participate. Completed responses, therefore,
in the manufacturing of the product. These
The first section of the survey solicited
were elicited from 62 (34%) of the 180 surveys
results are in agreement with others who have
information about the number of employees TGURE 1 22 Environmental Health January/February 1997 i1
Ii
i I I j i I 1 discussed computer chip manufacturing and
the ?&entia1 of replacing hazardous materials
withchemicals that are less hazardous and less
likelytoproducehazardouswaste(1,ii).When
computer chips are being formed, hazardous
chemicals are utilized to etch specific patterns
on the chip to match designated circuitboards.
This etching process occurs during the manufacturing process, and the etching chemicals
are removed by the time,the final product is
formed.
In order to determine which chemicals
used at the plants pose the greatest degree of
environmental hazard, participants were asked
to list the three most hazardous substances
used at their facility. Responses to this question vaned from common solvents such as
isopropylalcohol, which are generally accepted
as having low toxicity, to highly carcinogenic
compounds such as hydrofluoric acid, freon,
ammonium dichromate, trichloro-acetate,
photoresist solvents, and various heavy metals. As this list suggests, a wide variety of
compounds are used by the industry, which
makes producing a working model of less
hazardous materials even more difficult for
these businesses (1,5,6).
The participants also appeared to have
held widely different interpretations of the
term “hazardous” substance even though the
term “hazardous” is routinely defined as substances that are flammable, corrosive, reactive,
or toxic. Often, new products have not been
tested for long term health or environmental
effects and thus have not been fully categorizedas to their hazardous properties (12). For
example, a one percent sodium chloride solution is generally considered harmless, yet it is
corrosive and toxic over extended periods of
exposure (12). Researchers write about the
confusion that surrounds the term “hazardous,” and whether or not chemicals that are
hazardous to humans pose the same hazards to
the environment (3,13-15).
Almost halfof those completing the survey
indicated they had attempted incorporating
safer alternatives to the compounds mentioned
above in their production activities. When
questioned further as to the results of these
attempts, respondents indicated that most often the product change was implemented.
Reasons provided included that the new products worked well, were cost effective, and
saved worker time. There may be other reasons for switching to these new products;
however, the choices provided reflected current incentives demonstrated by other researchers (1.11,16,17). For example, somesemiconductor manufacturers recently have abandoned Industry definition of “green” or “environmentally safe/friendly”
products
Other
Better product performa Public relations Fewer injuries Reasons given for motivating electronics firms t o switch to less
hazardous products or processes
< 50% hazardous 1
ontains organic material o known hazards the use of CFCs as a solvent (due to the ozonedestroying properties of the chemicals). This
has resulted in lower costs and safer alternatives in the chip cleaning process (11).
Some experts suggest that pollution prevention options in the electronics industry
should focus on process modifications rather
than product substitutions (1).An example of
a process modification might be to control
crystal growth formations on the silicon chips
so the need for sandblasting and cropping is
greatly reduced. Another modification might
be to computerize the wafer slicing process
which would yield thinner and more uniform
slices (1). Still other modifications might include selecting the least hazardous production
process for operation or automating procedures so employee contact with potentially harmful products or processes is reduced (5). Barriers to Pollution
Prevention
Participants were asked to identify factors
that might discourage their businesses from
switching to less hazardous products or processes (see Figure 1). Slightly over one-third
indicated that new products/processes did not
workas wellas the current product or practice.
Eighteen percent did not believe their current
practices/products were hazardous. Prohibitive costs of conversion was a response chosen
by 13 percent of the participants; and, little or
no pressure from regulatory agencies to switch
was indicated by 3 percent of the respondents.
Twenty-eight percent marked the “Other” category and wrote in reasons such as “no alter- - January/February 1997 Environmental Health 23 _ WGURE
4
Industry’s opinion about who should take the leadership in
promoting pollution prevention natives available,” “need time to evaluate,” or
“must meet customer specifications.” These
barriers are not uncommon; other potential
barriers that have been previously recognized
are timescale constraints, growth expectations
from shareholders, and organizational bamers (18). Defining a ”Green”Product
Figure 2 reports how respondents would
best define a “green” or “environmentally
safdfriendly” product. Because there are no
legal definitions of these terms, choices given
in the survey reflected the variety of definitions that are frequently noted in the literature
(4,18). Forty-two percent defined these products as those that contain no known hazardous
chemicals; 19 percent defined “green” or “environmentally safdfriendly” products as those
containing only organic material, while an
equal number of participants supplied their
own definition in the “Other” category. These
unique definitions included: the product contains few hazardous chemicals and produces a
minimum of hazardous waste; a product that
can be managed and is not detrimental to the
environment or to worker safety; a product
that naturally decomposes without harmful
by-products; meets EPA guidelines; a product
which does not harm the environment; breaks 24 Environmental Health down into safe substances; and a product with
a recycled content greater than 20 percent.
Ten percent of the respondents defined “green”
products as those that contain ingredients
whose effects are known and waming labels
are provided and nine percent believed “green”
or “environmentally safdfnendly” products to
be any products the manufacturer labels as
such, These results are similar to information
that has been presented in other studies and
reiterate the need to standardize terms
(4,15,19).
Recent efforts in Europe and in the United
States have sought to standardize and certify
“green”labeling. For example, the Blue Angel
program, established in Germany in 1978,
awards a seal of approval to products whlch
are less harmful to the environment than others considered to be in the same category
(20,21). The seal of approval alerts and encourages consumers to buy products that are
less polluting and manufactured by industries
that have adopted cleaner production processes. The Blue Angel program is completely
voluntary, and a corporation must apply for
use of the official label (20).
The Green Seal and Green Cross organizations in the United States provide a relatively
unbiased evaluation of environmental product claims (22). Green Cross certifies the re- January/February 1997 cycled content of packages and is beginning to
use lifecycle analysis to assess all the environmental impacts of a product or package (22).
Green Seal sets standards for specific products, certifies brands, and awards the “Green
Seal” to products that meet certain standards
(21). The founders of Green Seal include a
group of scientists from academia, representatives from the Natural Resources Defense Council, Earthworks Press, the Council on Economic Priorities, Sierra Club, and the U.S.
Public Interest Research Group. The Green
Seal organization is funded by private donations (15).
A follow-up question on the survey asked
participantsif their facilitywaspresently using
any “green”or “environmentally safdfnendly”
products, as they had defined the term in the
previous question. Sixty percent of the respondents indicated their organization did use these
products. Participants were then asked to rank
in order of importance the reasons that their
corporations switched to less harmful products and/or processes. The highest ranking
response was the category designated “Other”.
Participants wrote in responses such as: safer
to use, lower health insurance premiums, company mandates, worker safety, no treatment
needed, saves resources, less hazardous to
employees and the environment, meets toxic
use reduction guidelines, and eliminated potential hazards. Ethical reasons were ranked
second as their reason for switching to less
hazardous products, followed in decreasing
order by lower costs, better results, and public
pressure. All of these choices reflect reasons
that have been discussed previously
(1 1,14,17,23,24).
A growing number of people no longer
view being “green” as a cost, but rather as an
opportunity to create new markets and products, thus creating a potentially wealthy business venture (11).Corporations utilizing pollution prevention strategies may, in fact, experience increased public support because community members, as well as workers within
the facility, are exposed less often to potentially harmful agents (24). In some instances,
grassroots organizations have pressured corporations to acknowledge environmental costs
associated with manufacturing processes, and
to acknowledge these hidden costs by asking
companies to adopt lifecycle accounting procedures (25). Ethical factors influencing environmental behaviors have been discussed by
the Washington State Department of Ecology
(14), who reported that successful pollution
prevention programs also must have an ethical
component. In addition, they found that tap- I
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1 i 7 ’ ping into employee imagination and creativity
wa+sential for the development of new products as wellas theadoptionofenvironmentally
conscious behaviors within the organization.
Higgins reiterates that companiesshould identify and support a champion - the individual
who originated the idea and who has extensive
experience with the process (22). This person
should be given the responsibility and the
authority to implement the change.
Respondents were then asked to list the
trade names of three of the “green” products
they have incorporated into updated environmental procedures and also list the more hazardous product(s1 being replaced. Examples
of substitutions included: (1) using hot water
as an alternative to freon products and
degreasers; and ( 2 ) substituting “eco” nuts,
scrap office paper, butcher paper, and real
popcorn for packing materials. Reasons Given for Switching to Less
Hazardous Products
While a previous questionasked why the
respondent’s particular facility switched to a
‘‘green” or “environmentally safe/friend]y”
product, a folIow-up question, “In your opinion, what would be the best factor to encourage an electronics fimto switch to using a less
hazardous product or process?” was asked to
gather infomation as to what factors respondents felt would encourage the industry to
adopt more environmentally conscious behaviors (see Figure 3). Twenty-nine percent
indicated cost savings as the top motivating
factor, whereas 20 percent reportedsafer products that worked better would encourage their
individual firm to be more environmentally
conscious. Ethical factors was chosen as a top
motivating factor by 14 percent of the participating respondents. Only three respondents
marked the response “more positive public
relations.” While these results are generally
supported by previous research, the results are
contradictory to studies that have found public relations to be a very strong factor influencing pollution prevention activities (3,25).
While this study showed that Oregon’s electronic firms appeared to put less emphasis on
public relations than other reasons for incorporating pollution prevention practices, the
fact that businesses are driven by cost factors
to make changes also has been demonstrated
by others (1,171.
Organization Incentives
When asked if their organization has received awards or recognition for utilizing poilution prevention strategies, Only 11 percent
replied yes. Eighty-nine percent reported that their organization had never received recognition for pollution prevention strategies. This
particular point has been brought by Kleiner
and others, who have explained the necessity
of using positive recognition as a method of
promoting environmentally conscious behaviors in other industries, and that financial
rewards are particularly attractive (24,26,27).
In fact, Higgins writes that “Recognition is a
powerful motivator. Rewarding successes is a
means of affirming an innovator’s decision to
do something different; rewards encourage
others to put in the extra effort to reduce
wastes so that they also can be recognized and
rewarded” ( 2 2 , p.55).
Respondents also believed the industry
should do more in the area of pollution prevention. Eighty-eight percent of the participants indicated that more progress should be
made toward this goal. When asked about who
should take the leadership in promoting pollution prevention, 55 percent believed that leadership in this area should come from the industry itself (see Figure $1. Fewerrespondents
(17 percent) indicated this leadership should
come from regulato’Y agencies such as DEQ,
Epz%
Or OccuPational Safety and Health Administration (OSHA). Even fewer participants
(7 percent) would like to see the leadership
coming from independent
firms Or
worker groups within the company. Write-in
suggestions provided by participants about
others who should take the lead in encouraging pollution prevention efforts included providing tax incentives, investment credits, or
scientific guidance. The results indicated that,
of the companies that responded, these participants would like to lead themselves when it
comes to pollution prevention. This infonnation is substantiated by efforts seen in other
industries. For example, Dow Chemical developed a pollution prevention program Waste
Reduction Always Pays (WRAP) on its own
accord, 3Minstitutedits ownsource reduction
programcalledPollutionPreventionPays (3P),
and Intel has voluntarily eliminated the use of
seven suspected carcinogens from all of the
company’s processes. Intel received the 1992
Oregon Governor’s Award for adopting a corporatephilosophy ofpollution preventionand
toxics reduction (28). These programs boast
of the
of reduced chemical usage,
decreased waste production, and increased
profits (1,27,28). Conclusions and
Recommendations
Respondents from Oregon’s electronics
industry who participated in this research in- dicated an interest in incorporating pollution
prevention practices into their manufacturing
processes. Many of the organizations have
implemented or are experimenting with the
use of less hazardous products and processes.
Participants indicated that these changes are
primarily driven by the desire to reduce productioncosts. For those who have yet to implement these practices, the main barriers to
incorporating pollution prevention strategies
into current processes are that new products
or processes do not work as well as current
practices, and that the costs of making the
initial switch are prohibitive.
Although no legal definitions exist for the
terms “green” or “environmentally safe/
friendly,” most respondents defined “green”
or “environmentally safdfriendly ,” products
as those that contain no known hazardous
chemicals. Other responses included defining
these products as those which contain only
organic materials, products which contain few
hazardous chemicals and produce a minimum
of hazardous waste, and products whichnaturally decompose without harmful by-products. The variety of responses demonstrates
the existing confusion regarding the meaning
of these terms.
Economic factors were viewed as the primary incentives that might encourage the industry tobemoreproactiveinswitchingtoless
hazardous products or processes. Those participating in this study rated cost savings and
the availability of environmentally sound products that would perform as well as original
materials as primary incentives for making
changes. Ethical considerations were a third
reason for switching to less hazardous products.
The vast majority of respondents believe
more efforts should be directed toward pollution prevention activities. Most would like to
see leadership in this area coming from the
industry itself rather than regulatory agencies,
such as the EPA, OSHA,or the state DEQ.
Although the survey resul...
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