biodiesel en minas subterraneas.pdf

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ECONOMIC COMPARISON OF BIODIESEL BLENDS TO

COMMERCIALLY AVAILABLE EXHAUST EMISSION

REDUCTION TECHNOLOGIES FOR UNDERGROUND MINES

Final Report to the National Biodiesel Board

University of Minnesota

Kenneth L. Bickel

Joseph McDonald

Center for Diesel Research

Jerry E. Fruin

Douglas Tiffany

Department of Agricultural and Applied Economics

January 1997

Contact: Ken Bickel, Research Fellow

E-mail: [email protected]

Telephone: 612-725-0760, Extension 4581

Joseph McDonald, Research Fellow

E-mail: [email protected]

Telephone: 612-725-0760, Extension 4535

University of Minnesota - Center for Diesel Research

125 M.E.111 Church St. S.E.

Minneapolis, MN 55455-0111

Facsimile: 612-725-0800


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Table of Contents

LIST OF TABLES AND FIGURES...........................................................................................................................3

EXECUTIVE SUMMARY.........................................................................................................................................4

I. PROJECT OBJECTIVES......................................................................................................................................7

II. INTRODUCTION .................................................................................................................................................7

CURRENT U.S. AIR QUALITY REGULATIONS IN UNDERGROUND MINES ....................................................................7CERTIFICATION, APPROVAL, AND REGULATION OF DIESEL EQUIPMENT IN UNDERGROUND MINES ..........................8PM-EMISSION CONTROL FOR DIESEL EQUIPMENT IN UNDERGROUND MINES..........................................................11

III. COMPETING PM-EMISSION CONTROL STRATEGIES FOR DIESEL UNDERGROUND MINING

EQUIPMENT.............................................................................................................................................................12

DIESEL-POWERED UNDERGROUND MINING EQUIPMENT, PM-CONTROLS, AND TERMINOLOGY ..............................12

IV. SOURCES OF DATA FOR COST ANALYSES.............................................................................................15

VEHICLE LIFE AND USAGE.......................................................................................................................................15VEHICLE EMISSIONS AND EMISSIONS CONTROLS.....................................................................................................15FUEL CONSUMPTION AND COSTS..............................................................................................................................16LABOR COSTS ..........................................................................................................................................................16

V. EQUIPMENT LIFE CYCLE COSTS OF EMISSION CONTROLS VERSUS BIODIESEL.....................18

VEHICLE SELECTION FOR COST ANALYSIS ..............................................................................................................18SELECTION OF PM-EMISSION CONTROLS.................................................................................................................18PM-EMISSION CONTROL STRATEGIES FOR THE EQUIPMENT LIFE-CYCLE ANALYSIS...............................................20RESULTS FROM EQUIPMENT LIFE CYCLE COST ANALYSIS.......................................................................................25

VI. METHODS OF CONDUCTING DISCOUNTED COST ANALYSES OF AN UNDERGROUND COAL

MINE AND AN UNDERGROUND METAL MINE..............................................................................................27

BACKGROUND .........................................................................................................................................................27

SELECTION OF CASE STUDY MINES .........................................................................................................................28METHODS OF ANALYSIS ..........................................................................................................................................29DATA ANALYSIS......................................................................................................................................................32

VII. RESULTS FROM METAL MINE DISCOUNTED COST ANALYSIS ........... .......... ........... ........... ..........34

SENSITIVITY ANALYSIS............................................................................................................................................34

EFFECT OF DISCOUNT RATES...................................................................................................................................34EFFECT OF BLEND LEVELS AND BIODIESEL COST ....................................................................................................35EFFECT OF MINE LIFE ..............................................................................................................................................36EFFECT OF TARGETING HEAVY-DUTY, NONPERMISSIBLE DIESEL EQUIPMENT ........................................................36EFFECT OF TARGETING LIGHT-DUTY, NONPERMISSIBLE DIESEL EQUIPMENT..........................................................36

VIII. RESULTS FROM COAL MINE DISCOUNTED COST ANALYSIS ......................................................38

SENSITIVITY ANALYSIS............................................................................................................................................38EFFECT OF DISCOUNT RATE.....................................................................................................................................39EFFECT OF BLEND LEVEL AND BIODIESEL COST......................................................................................................39EFFECT OF MINE LIFE ..............................................................................................................................................39

EFFECT OF TARGETING CATEGORY A DIESEL EQUIPMENT......................................................................................39EFFECT OF TARGETING LIGHT-DUTY (NONPERMISSIBLE) DIESEL EQUIPMENT ........................................................39EFFECT OF LOST PRODUCTION (COAL MINE USING DDEFS) ....................................................................................41

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IX. CONCLUSIONS AND RECOMMENDATIONS...........................................................................................42

CONCLUSIONS .........................................................................................................................................................42

RECOMMENDATIONS ...............................................................................................................................................44

REFERENCE LIST ..................................................................................................................................................45

APPENDIX I: COMPARISON OF CAPITAL AND OPERATING COSTS FOR ONE ELECTRIC COALHAULAGE VEHICLE VERSUS ONE DIESEL AND ONE BIODIESEL-POWERED VEHICLE ................48

List of Tables and FiguresTABLE 1: EQUIPMENT IDENTIFIED FOR THE LIFE-CYCLE COST ANALYSIS, AND EXHAUST AFTERTREATMENT OPTIONS

CONSIDERED FOR EACH CLASSIFICATION AND TYPE OF DIESEL EQUIPMENT.........................................................19

TABLE 2: SUMMARY OF VEHICLE LIFE CYCLE COSTS FOR EMISSION CONTROLS AND BIODIESEL FUEL WITH DOCS .....25TABLE 3: CASE STUDY METAL MINE: EQUIPMENT LIST, EMISSION CONTROLS AND FUEL USE ......................................28TABLE 4: CASE STUDY COAL MINE: EQUIPMENT LIST, EMISSION CONTROLS, AND FUEL USE .......................................29TABLE 5: EXAMPLE OF A SPREADSHEET FOR A RAM-CAR USING DDEFS. ....................................................................30TABLE 6: EXAMPLE OF A SUMMARY SPREAD-SHEET FOR THE CASE-STUDY METAL MINE USING BIODIESEL WITH DOCS.33

TABLE 7: METAL MINE - COMBINATIONS OF DISCOUNT RATE, BIODIESEL COST, AND BLEND LEVEL............................34FIGURE 1: METAL MINE: BLEND LEVEL VERSUS REDUCTION IN AMBIENT PM CONCENTRATION AND DISCOUNTED

BIODIESEL AND DOC COST/SHORT TON OF ORE PRODUCED. ...............................................................................35TABLE 8: METAL MINE VEHICLE FLEET PM REDUCTIONS AND DISCOUNTED COSTS OVER THE 24 YEAR MINE LIFE

USING NEAT BIODIESEL VS. FILTERS ON HEAVY-DUTY AND LIGHT-DUTY EQUIPMENT..........................................37TABLE 9: COAL MINE - COMBINATIONS OF DISCOUNT RATE, BIODIESEL COST, AND BLEND LEVEL ...............................38FIGURE 2: COAL MINE: BLEND LEVEL VERSUS REDUCTION IN AMBIENT PM CONCENTRATION AND DISCOUNTED

BIODIESEL AND DOC COST/SHORT TON OF ORE PRODUCED. ...............................................................................40TABLE 10: COAL MINE VEHICLE FLEET PM REDUCTION AND DISCOUNTED COSTS USING NEAT BIODIESEL VS. FILTERS

ON HEAVY-DUTY AND LIGHT-DUTY EQUIPMENT OVER A 24 YEAR LIFE OF THE MINE...........................................41TABLE A1: CAPITAL AND OPERATING COSTS FOR ONE 10-TON ELECTRIC COAL HAULER VERSUS ONE DIESEL AND

BIODIESEL-POWERED COAL HAULER...................................................................................................................48

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Executive Summary

The National Institute for Occupational Safety and Health recommends that whole diesel exhaustbe regarded as a "potential occupational carcinogen," and that reductions in workplace exposurewould reduce carcinogenic risks. The Mine Safety and Health Administration (MSHA) has

recently adopted new approval and certification regulations for diesel equipment, and proposedmore stringent air quality regulations including a proposal to regulate diesel particulate matter(PM).

In 1995, MSHA convened a committee to recommend regulations to minimize DPM exposureand consider a possible permissible exposure limit for PM, and the American Conference ofGovernmental Industrial Hygienists added PM to the List of Intended Changes for 1995-96 witha threshold limit value (TLV

TM) recommendation of 0.15 mg/m

3. If MSHA were to adopt this

TLVTM

for underground mines many mines using diesel equipment in the U. S. would be out ofcompliance. Typical mean concentrations of DPM in mines range from 0.2 to 1.5 mg/m

3. This

TLVTM

would impose limitations on the current and future use of diesel equipment unless

improved emission control strategies are developed for the mining industry.

Biodiesel is a common term for a number of different alkyl mono-esters of fatty acids that can beused as diesel fuel or blended with petroleum diesel fuels. Neat biodiesel fuels and blends ofbiodiesel and petroleum diesel fuels can be used to lower PM-emissions. The fuel-bound oxygenof biodiesel fuels considerably reduces the formation of the carbon-soot constituents of PM. Theprices of likely biodiesel fuels are higher and more volatile than petroleum diesel fuels.Biodiesel fuels offers the potential for substantially reducing PM-emissions without the need forminer training, or the maintenance and replacement of hardware required by other PM-emissionscontrol strategies. For that reason, the National Biodiesel Board initiated a project with theUniversity of Minnesota - Center for Diesel Research to compare the costs of using a common,

neat biodiesel fuel and biodiesel fuel blends to the costs of using other types of emissionscontrols in underground mines.

The overall objective of this project was to compare the cost of using neat biodiesel fuel andblends of biodiesel and petroleum diesel fuel to the cost of using other emission controls thatmay be used in underground mines. The specific goals were to evaluate the equipment life cyclecosts of converting mine equipment to different types of emission controls, and to develop twocase study examples of the net present value costs of converting mining equipment to biodieseland emission controls.

This report reviews emission control technology for underground diesel-powered equipment, andcompares the life cycle costs of using emission controls and biodiesel and biodiesel blends forten mine vehicles. It also gives the results from two discounted cost analyses of using biodieseland emission controls in a metal mine and a coal mine.

The equipment life cycle analyses indicated that biodiesel at $1.50/gal may be a viable PM-control strategy for light-duty nonpermissible equipment, and some types of permissible

equipment. It does not look competitive on heavy-duty nonpermissible equipment. The use of

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exhaust filters for PM-control will result in ambient PM reductions exceeding 65%, and mineoperators would need to use straight biodiesel with catalytic converters to get comparablereductions.

Based on the discounted cost analyses, it appears that biodiesel will need to fall below $2.00/gal

to be competitive with filters for coal mines, and below $1.25/gal for metal mines. However,biodiesel has advantages that filters do not. The use of biodiesel in mines would be easy toimplement, and would not require miner training. There are no new maintenance proceduresintroduced, whereas machines are pulled out of production to replace, regenerate, or performmaintenance on filters. These procedures will undoubtedly introduce "hidden costs" notcompletely accounted for in this study. Cost will be one factor mines will consider whenchoosing PM-emissions control strategies, but the amount of PM reduction required, and thesimplicity and ease with which the method of control can be implemented and used will also beimportant factors for mines to consider.

Further research involving the use of biodiesel fuels in underground mines is needed. The report

recommends that 1) further laboratory and field evaluations be conducted to quantify PMreductions using biodiesel blends and modern engines, 2) the market for biodiesel be determinedthat will allow the price of biodiesel to drop below $2.00/gal, and 3) the cost of biodiesel use fordifferent sized mines with differing complements of equipment be investigated.

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I. Project Objectives

The overall objective of this project was to compare the cost of using neat biodiesel fuel andblends of biodiesel and petroleum diesel fuel to the cost of using other emission controls that

may be used in underground mines. The specific goals were to:

List available and pending emission controls that could be used by mine operators overthe next five years to reduce emissions.

Evaluate the equipment life cycle costs of converting mine equipment to three presentlyavailable emission controls. Evaluate the equipment life cycle costs of converting mineequipment to one emission control that will soon become available.

Develop two case study examples of the net present value costs of converting miningequipment to biodiesel versus the most competitive current or potential emission control.

II. Introduction

Current U.S. Air Quality Regulations in Underground Mines

Air Quality - Ambient air quality standards for surface and underground mines in the U.S. areregulated by the Mine Safety and Health Administration (MSHA) through the establishment andenforcement of permissible exposure limits (PELs) for a number of air contaminants (30 CFR,Parts 56, 57, 70, 71, 74)

a. MSHA is an agency of the U.S. Department of Labor currentlyresponsible for the regulation of worker health and safety in the U.S. Current PELs in force forthe underground mining industry in the U.S. reference the TLV

TMconcentrations for airborne

contaminants as given in the 1973 edition of the American Conference of GovernmentalIndustrial Hygienists (ACGIH) Handbook (ACGIH 1973). Many constituents of diesel exhausthave PELs established by MSHA, including NO, NO2, CO, CO2, and formaldehyde. Inunderground coal mines, there is an additional PEL for respirable dust

bof 2.0 mg/sm

3. In

underground coal mines that utilize continuous mining machines and diesel haulage,approximately 50% of the respirable dust is due to particulate matter (PM)

cemissions from

diesel equipment. There is currently no separate MSHA PEL established for PM from dieselexhaust in the U.S.

In 1988, the National Institute for Occupational Safety and Health (NIOSH) recommended thatwhole diesel exhaust be regarded as a "potential occupational carcinogen," and that reductions in

a References are cited within parentheses and in italics. A complete reference list has been included at the end of this report.

b Respirable dust is defined by the sampling method described in 30 CFR, Part 74. To summarize, it is the particle mass collected using a personal dust sampler incorporating an

approved cyclone pre-classification stage with a 50% cutpoint diameter of 3.5 m. Thus, the respirable dust concentration is essentially the sub-3.5 m aerodynamic-diameter

ambient PM concentration.

c Many sources of particulate matter exist within underground mines. All references to PM pertain to particulate matter formed by diesel combustion. It will be referred to either

as PM-emissions (EPA laboratory dilution tunnel measurement methods) or as ambient PM (ambient concentrations determined using USBM, MSHA, CANMET, or NISOSH

sampling procedures).

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workplace exposure would reduce cancer risks (NIOSH). In 1989, the International Agency forResearch on Cancer (IARC) declared that diesel engine exhaust is probably carcinogenic tohumans (IARC). In 1995, the ACGIH added PM to the List of Intended Changes for 1995-96with a TLV

TMrecommendation of 0.15 mg/m

3(ACGIH 1995). In 1994, MSHA convened the

Diesel Advisory Committee to recommend regulations to minimize PM exposure and consider a

possible permissible exposure limit for PM (61 FR 208). Recommendations have beensubmitted to the Secretary of Labor from the Diesel Advisory Committee, but actions to limitPM from diesel equipment in mines are still pending.

Typical mean concentrations of PM in mines range from 0.2 to 1.5 mg/sm3(Watts, 1995). IfMSHA were to adopt the TLV of 0.15 mg/sm3as an exposure limit for ambient PMconcentrations in underground mines, nearly all mines using diesel equipment in the U. S.(approximately 82 % of 468 mines) would be out of compliance (Watts, 1997). Regulation ofambient PM concentrations have the potential to severely limit current and future use of dieselequipment in underground mines unless improved emission control strategies are developed forthe mining industry.

Certification, Approval, and Regulation of Diesel Equipment in Underground Mines

On November 1, 1996, new rules were established with regards to the certification and approvalof diesel equipment used in underground coal mines (61 FR 208). The 30 CFR, Part 7 final ruleeliminated 30 CFR, Part 32 (voluntary approval of diesel equipment for metal and nonmetalmines), and superseded certification of permissible diesel coal mine under 30 CFR, Part 36.Diesel equipment used in underground coal mines must now be certified for use by MSHA underthe provisions of Title 30 CFR, Part 7. The new Part 7 rules established two categories of dieselequipment for underground coal mines, modified the calculation of ventilation rates for dieselequipment, modified the fuel requirements for underground coal mines, and otherwise modified

or updated federal regulations pertaining to the use of diesel equipment in underground coalmines.

Category A (Permissible Diesel Equipment) - Category A certification under 30 CFR, Part 7,is required for diesel equipment operated in underground mines that contain potentiallyexplosive mixtures of methane gas and/or coal dust in the air. In the U.S, this would beprimarily in underground coal mines near the mine face (or in-by)dareas.

The equipment (diesel or otherwise) operated under these conditions is commonly referred to inthe mining industry aspermissible equipment. Permissible diesel equipment must be certified tomeet a number of MSHA requirements. The equipment must be explosion proof, and the

temperatures of surfaces must be maintained below 150 C. Exhaust temperatures are restrictedand the equipment must utilize a means of arresting potential sparks from the intake or exhaustsystems. Current permissible diesel equipment designs use a water jacketed exhaust system, anair-intake spark arrestor, and a water-bath exhaust conditioner (commonly referred to as a water-scrubber) to meet temperature, spark arrestment, and explosion-proofing requirements. A means

d In typical underground coal mining practice, the in-by area is the area inside of the last open cross-cut, towards the face area of the mine. The out-by area is the entire region

outside of the last open cross-cut, away from the face.

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of rendering the safety device tamper-proof, such as the low-water engine cut-off used withwater scrubbers, is also necessary. Permissible diesel equipment using water-scrubbers are

required to maintain their exhaust temperature at or below 76 C.e

Permissible exhaust cooling systems for diesel equipment that eliminate the water bath and its

maintenance requirements have been under development for over 10 years(Waytulonis andBickel, 1988). These systems are referred to within the mining industry as dry exhaustconditioning systems or dry-scrubber systems. Two systems were recently certified by MSHAfor retrofit usage on two particular coal haulage vehicles. Dry exhaust system safetyrequirements are the same as for other Category A diesel equipment, with the exception that

higher exhaust temperatures are allowed (150 C vs. 76 C) and that a separate exhaust sparkarrestor is necessary. Category A diesel equipment is primarily heavy-duty production

equipment, such as coal haulage vehicles, with naturally aspirated, indirect injection dieselengines rated between 50 and 150 brake-horsepower (b.h.p.).

Category B (Nonpermissible Diesel Equipment) -Category B certification under 30 CFR,

Part 7, is required for diesel equipment operated in areas of coal mines not regulated underCategory A. Areas of the mine further away from the mine face (the out-by area) havelower concentrations of methane gas and coal dust, and thus the use of permissible equipment isnot considered necessary. Equipment used in underground metal and nonmetal mines is alsooften referred to as nonpermissible equipment since they are not typically operated in anexplosive environment. Metal and nonmetal diesel mining equipment are not currently regulatedunder federal law in the U.S. Nonpermissible, Category B diesel equipment does not require theextensive exhaust cooling and surface temperature measures of Category A equipment.Category B equipment is comprised primarily of light-duty diesel equipment, such as personneltransports.

Ventilation Requirements -A mine ventilation rate for each piece of Category A or CategoryB diesel equipment is determined from gaseous exhaust emissions. The gaseous emissions aremonitored as the engine is operated over the ISO 8178-C1 steady-state test-cycle (61 FR 208).This particular test cycle is also used for EPA, CARB, and EU compliance testing of off-highway diesel engines. The ventilation rates necessary to dilute NO, NO2, CO, and CO2to theirrespective MSHA PEL values are calculated for each steady-state operating condition. Thehighest ventilation rate (rounded to the nearest 500 or 1000 scfm) is then assigned as theventilation rate for the engine. The ventilation rate is recorded on a certification tag affixed tothe engine. When operated in an underground coal mine, each piece of diesel equipment must besupplied with a ventilation rate at least equivalent to the ventilation rate assigned to the engine.A particulate index ventilation rate is also calculated from monitoring PM-emissions over the

ISO 8178-C1 test cycle, but it is only used as a recommended guideline for ventilation until anMSHA PEL is established for PM-emissions.

Underground Metal and Nonmetal Mines -Although metal and nonmetal mines are excluded

from the requirements of Category B certification, many state statutes require approval testing

eThe temperature limit of 76 C is approximately the adiabatic saturation temperature of 500 C diesel exhaust. It was by chosen by MSHA to ensure proper operation of the

water-scrubber design.

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and assignment of a ventilation rate under by MSHA under 30 CFR, Part 32. As originallyconceived, 30 CFR, Part 32 did not carry the force of federal law. It was established as aguideline of good engineering practices when using nonpermissible diesel equipment inunderground metal and nonmetal mines. The 30 CFR, Part 32 guidelines included thecalculation of a ventilation rate based on gaseous exhaust emissions using a similar test

procedure to those described in the Part 7 rules. The respective engines were then assigned anapproval tag by MSHA stating the recommended ventilation rate

f. The 30 CFR, Part 32

approval procedure has been eliminated and totally superseded by 30 CFR, Part 7. The Part 7rules currently do not apply to noncoal mine applications. The effect of these recent changes to30 CFR on state statutes is still uncertain.

Engine manufacturers for underground metal and nonmetal mining applications are now in theprocess of certifying engines under Category B of 30 CFR, Part 7, even though many of theseengines will likely never be used in coal mine applications. Some of the reasons for voluntarilyobtaining Part 7 certification for diesel applications not regulated under federal law include:

1. New, underground metal and nonmetal mines must submit a ventilation plan to MSHA priorto beginning mining operations. Many noncoal mines will not consider using uncertifiedengines because of the difficulty in gaining MSHA approval of ventilation plans. Theventilation plans rely heavily on ventilation rates calculated from the MSHA tag assigned toeach piece of equipment used. The ventilation rates provided with Part 32 approval tags orby voluntarily submitting the engine to compliance testing for assignment of a Part 7certification tag allow new mines to reference these ventilation numbers to MSHA as part ofthe ventilation plan.

2. States statutes that currently refer to the now superseded 30 CFR, Part 32 may eventually bemodified to reference 30 CFR, Part 7, Category B certification.

3. Engine and equipment manufacturers realize the advertising value of seeking MSHAventilation rate tags for their equipment. Many mines only buy equipment with MSHAapproval or certification tags because it is considered to be a good engineering practice.

Fuel Requirements -The new 30 CFR, Part 7 rules require the use of low sulfur (< 0.05 mass

%) diesel fuel in underground coal mines. The fuel flashpoint must be 38 C, and the fuel mustnot contain any additives not currentlyregistered with the U.S. Environmental ProtectionAgency in accordance with 40 CFR, Part 79. If used as a fuel additive

gfor underground coal

mine applications, biodiesel fuels would either need to be currently registered with the EPA asan additive, or special permission from MSHA would be required prior to its use (Saseen). For

use as an alternative fuelhin coal mines, special permission from MSHA would be required(Saseen). These restrictions do not apply to underground metal or nonmetal mines.

f MSHA considers Certification to be mandatory and Approval to be voluntary.

g Less than 50 %, (by mass) blended with approved petroleum diesel fuel.

h Neat (100%) biodiesel or a blend of more than 50% (by mass) biodiesel with approved petroleum diesel fuel.

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PM-Emission Control for Diesel Equipment in Underground Mines

Mined materials occur in a wide variety of situations. Many physical, geologic, environmental,legal, and economic circumstances dictate the mining method used to recover the materialmined. These circumstances determine the required production level, production rate, size of

openings, and other factors that dictate the type and the size of mining equipment selected.Many other factors influence how mining is conducted, how equipment is used, and the extent towhich miners are exposed to air contaminants, thus each mine is nearly unique. A mine mightselect any combination of methods for limiting exposure to air contaminants, and the methodsselected could be unique to that particular mine. These methods include proper ventilation, goodengine selection and maintenance, the use of quality fuels, and modification of the fuel injectionrate of diesel engines.

Different types of PM-emission control devices are also used to reduce exposure to ambient PMin underground mines. The performance of emission controls is heavily dependent on exhausttemperature. In coal mine applications, the exhaust temperature on Category A vehicles cannot

exceed 150oC. Exhaust temperatures on Category B equipment can vary widely, and are heavilydependent on the vehicles duty cycle. Category B vehicles can be classified as being heavy-duty (with consistently high exhaust temperatures) or light-duty (with consistently low exhausttemperatures). Different emission control devices have been developed for Category A,Category B heavy-duty, and Category B light-duty equipment. Similarly, the exhausttemperatures and PM-emission control devices of diesel equipment used in underground metaland nonmetal mine applications varies widely, depending on the duty cycle, size, and type ofequipment used.

Biodiesel is a common term for a number of different alkyl mono-esters of fatty acids that can beused as diesel fuel or blended with petroleum diesel fuels. Neat biodiesel fuels and blends of

biodiesel and petroleum diesel fuels can be used to lower PM-emissions. The fuel-bound oxygenof biodiesel fuels considerably reduces the formation of the carbon-soot constituents of PM. Theprices of likely biodiesel fuels are higher and more volatile than petroleum diesel fuels.Biodiesel fuels offers the potential for substantially reducing PM-emissions without the need forminer training, or the maintenance and replacement of hardware required by other PM-emissionscontrol strategies. For that reason, the National Biodiesel Board initiated a project with theUniversity of Minnesota - Center for Diesel Research to compare the costs of using a common,neat biodiesel fuel and biodiesel fuel blends to the costs of using other types of emission controlsin underground mines.

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III. Competing PM-emission Control Strategies for Diesel Underground

Mining Equipment

Diesel-powered Underground Mining Equipment, PM-controls, and Terminology

The different classifications and regulated categories of diesel equipment in underground minescan be quite confusing for readers who are not intimately familiar with the underground miningindustry. Three very broad equipment classifications can be drawn from the federally regulatedequipment categories and from industry-wide practices in underground coal, metal, and nonmetalmines:

1) Category A equipment: This equipment is often referred to as permissible dieselequipment, or as coal-mine diesel face-equipment. For the purposes of this discussion,the authors will extend the definition of Category A to include older equipment certified

under 30 CFR, Part 36 in addition to the usual definition of newer equipment certifiedunder 30 CFR, Part 7, Category A. This category consists primarily of coal haulageequipment. Examples include the Jeffrey 4110 and 4114 Ramcars. Indirect injection(IDI), naturally aspirated diesel engines rated between 50 and 150 b.h.p. are typicallyused. Current and potential PM-emission controls include:

Waterbath Exhaust Conditioners: Waterbath exhaust conditioners, morecommonly known as water scrubbers, are safety devices designed to cool theexhaust and arrest flames and sparks. They are used on Category A permissibleequipment operating in the in-by areas of coal mines and gassy noncoal mines.They are an incidental emission control because they remove up to 30 pct ofdiesel exhaust aerosol.

Dry Exhaust Conditioning System: The dry exhaust conditioning system isbeing developed to replace water scrubbers and to lower PM-emissions fromCategory A diesel equipment. Units already in production combine a catalyst, aheat exchanger, a flame arrestor, and a disposable filter into one unit (Brezonick).The catalyst oxidizes carbon monoxide (CO) and FID-hydrocarbons (HC) presentin the diesel exhaust. Although the catalyst assists in reducing the amount of sootfouling within the heat exchanger, a water spray system has been incorporatedinto the heat exchanger to periodically clean the heat exchanger surfaces.Exhaust is cooled in one section of the heat exchanger by engine coolant flowing

through the other section. Because of the additional heat load on the enginecooling system, a much larger radiator and fan must be installed on the miningequipment. After the heat exchanger a mechanical flame arrestor is used toprevent exhaust flames from exiting the system. Finally, a DDEF is used toremove PM-emissions from the engine exhaust. The DDEF also acts as a sparkarrestor in the dry conditioning system, thus the dry system must use the DDEF inorder to maintain 30 CFR, Part 7, Category A compliance. The PM removal

efficiency is essentially that of a DDEF. Currently, dry systems have found only

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limited use in underground mines. This is primarily due to the cost and thecomplexity of dry systems compared to wet scrubbers.

Disposable Diesel Exhaust Filter (DDEF): The DDEF is similar to an intake airfilter used on heavy-duty over-the-road trucks. It is placed downstream of a waterscrubber in order to filter the cooled engine exhaust. The DDEF can only be used

on Category A vehicles equipped with water scrubbers. The DDEF is discardedafter being loaded with PM. Tests of the DDEF at two underground coal minesresulted in 70 to 95 pct reduction in diesel exhaust aerosol (Ambs, et al, 1994). Acommercial system is now manufactured for Jeffrey 4110 and 4114 Ramcars.

2) Heavy-duty, nonpermissible equipment: Although some heavy-duty nonpermissibleequipment is used in coal mines, this equipment category will refer to non-federally-regulated, heavy-duty production equipment used in metal and nonmetal mines for thepurposes of this discussion. Examples of this equipment include scoop-trams or load-haul-dump vehicles (LHDs), drills, roof-bolters, haulage trucks, and front-end-loaders.The duty-cycle, size, and type of this category of equipment can vary widely. Engines

are typically IDI, either naturally aspirated or turbocharged, and are rated between 80 and270 b.h.p. Some mines, including some underground salt mines, nickel mines, and lead-zinc mines, use diesel equipment with modern, turbocharged DI engines having power-output ratings of 270 to 400 b.h.p., and in some cases exceeding 500 b.h.p. Current PM-emission controls include:

Ceramic Wall-flow Diesel Particulate Filter (CDPF): Laboratory evaluationshave shown that of CDPFs have the potential to reduce PM-emissions by up to 90pct. However, two evaluations of CDPFs in underground metal mines measuredPM reductions of about 70% (Watts, et al, 1995). Exhaust passes through thewalls of the CDPF, trapping PM and slowly increasing engine back pressure andexhaust temperature. Eventually, the regeneration temperature of the CDPF is

reached. The use of CDPFs is limited to nonpermissible heavy-duty minevehicles with sufficiently high exhaust temperatures to sustain regeneration.Regeneration is the burning off of accumulated particulate matter to clean thefilter. Regeneration temperature is usually lowered by the application of acatalyst or regeneration is assisted by the use of on and off-board regenerationsystems. The high exhaust temperatures required for regeneration limit theapplication of CDPFs to heavy-duty non-permissible vehicles in noncoal mines.Better methods to ensure regeneration are required if CDPFs are to be usedsuccessfully on a wide array of mine vehicles (Baz-Dresch et al., Bickel andMajewski).

Diesel Oxidation Catalysts (DOCs): DOCs are flow-through devices that pass

hot exhaust gases through a honey-comb shaped monolith containing preciousmetal catalysts that drive reactions to oxidize carbon monoxide and organic gasesto carbon dioxide and water vapor. DOCs can be used on light-duty or heavy-duty non-permissible vehicles. DOCs are particularly well suited for oxidizing theorganic compounds generally associated with the disagreeable odor of dieselexhaust. Degradation of the air quality is likely to occur when fuel containingmoderate or high sulfur is used because the sulfur is oxidized to form sulfate(primarily sulfuric acid aerosol), which increases PM-emissions. High fuel sulfur

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IV. Sources of Data for Cost Analyses

Vehicle Life and Usage

Power Systems Research, Inc., under contract with the NBB, recently completed a survey of the

underground mining market (Power Systems Research). The survey results indicated that thetypical life for diesel-powered equipment in underground mines was 10-11 years, with haulageequipment having somewhat shorter lifetimes than utility equipment due to their morecontinuous usage and heavier duty-cycles. For the cost analyses, equipment lifetimes of 8-12years were assumed based on the number of hours of equipment usage per year. The PowerSystems Research survey also reported the average number of hours different types of equipmentoperate per year. These yearly averages were used for the cost analysis and were rounded to thenearest hundred hours per year.

Vehicle Emissions and Emissions Controls

Emissions data published by manufacturers, the USBM, and emissions data from engines testedat the CDR were used to estimate baseline particulate matter emissions on petroleum dieselfuels. Emissions from engines for which no published data existed were predicted based onengine design and regulatory requirements. Particulate matter reductions for the biodiesel fuel,the biodiesel fuel blends, and the exhaust aftertreatment devices were calculated fromcomposites of laboratory and field data from the CDR, USBM, and others (Ambs, Bickel andMajewski, Bickel and Taubert, McDonald et al. 1997, McDonald et al. 1995). The baselineemissions and emissions reductions were used to model expected reductions in ambient PMconcentrations for the various emissions control strategies. In cases where insufficient ambientPM data existed for a particular control, laboratory data was substituted by estimating acorrection factor for the relative differences in organic PM between typical ambient PM samples

and typical PM samples taken from laboratory dilution tunnels (Reichel et al.). An averagesoluble organic fraction of 40% at a dilution ratio of 15:1 was assumed for the laboratory

dilution-tunnel measurements of PM-emissions based on previous transient and steady stateemissions data (McDonald et al. 1995, Purcell et al.). Ambient dilution with ventilation air wasestimated to be approximately 40:1 by comparing laboratory measurements of engine exhaustflow for a 75 kW IDI diesel engine over a 90% duty-cycle (Purcell et al.)to the MSHAventilation rate for the engine (U.S. Dept. of Labor-MSHA). The correction factor for PM mass-emissions from laboratory to ambient dilution was then estimated using thecondensation/adsorption model presented inReichel et al.

It should be noted that no field data currently exists for the levels of ambient PM reductionpossible using biodiesel blends in underground mines. Only field data for neat, soy-methyl-esterbiodiesel and laboratory data for both neat biodiesel and biodiesel blends (for numerous types ofmono-ester biodiesels) currently exists. It is quite possible that actual ambient PM reductions forthe biodiesel blends will differ from those projected by the model used for this study. Researchis currently under way to directly determine the ambient PM reductions possible using biodieselfuel blends (DEEP).

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Emission control capital costs were obtained from suppliers of the controls and from minevehicle manufacturers. If possible, the assumed life and maintenance requirements for theemission controls were based on information obtained by the CDR or the USBM during in-mineevaluations of emission controls. Durability issues were also discussed with emission controlsuppliers.

Fuel consumption and Costs

Diesel fuel consumption data was obtained from Western Mine Engineering (Western MineEngineering-1, 1996). This is the mining industrys standard reference for cost estimating. Adiesel fuel price of $0.70/gal was assumed for the analysis based on the current contract price oflow sulfur diesel fuel as delivered to a large metal mine in the upper Midwest in May, 1996. Afuel consumption penalty of 3% was assumed when machines are equipped with DDEFs due toincreased exhaust back-pressure from the DDEFs loading with PM (MacDonald and Simon,Pischinger et al.).

Biodiesel fuel consumption relative to that of petroleum diesel fuel has been previouslydemonstrated to be closely related to its net energy content with no relative difference in cyclethermal efficiency (McDonald et al. 1995, Schmidt and Van Gerpen, Last et al., Needham and

Doyle). Because the fuels perform with equivalent cycle thermal efficiency (th), biodiesel fuel

consumption can be accurately estimated if the brake-specific fuel-consumption (BSFC) andlower heating value (QLHV) for a particular combination of engine and petroleum diesel fuel isknown:

th,biodiesel = th,petrodiesel

[QLHV* BSFC]biodiesel= [QLHV* BSFC]petrodiesel

[BSFC]biodiesel= [QLHV* BSFC]petrodiesel[QLHV]biodiesel

Biodiesel fuel consumption for this study was estimated by comparing the lower heating value ofdistilled Proctor and Gamble soy-methyl-esters (37.1 MJ/kg) to that of a commercial grade oflow sulfur (


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control devices were obtained from 1996 salary cost surveys(Western Mine Engineering-2 andWestern Mine Engineering-3, 1996). The labor costs included company-provided benefits suchas vacation, health and life insurance, and sick leave, as well as mandated benefits such asworkers compensation, unemployment insurance, social security, and Medicare.

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V. Equipment Life Cycle Costs of Emission Controls versus Biodiesel

The evaluation of equipment life cycle costs of using biodiesel compared to other emissionscontrols was conducted by first selecting different types of vehicles for evaluation, reviewingemission control technologies, selecting appropriate types for analysis and determining the life

cycle costs of using biodiesel and biodiesel blends versus emissions controls on selectedvehicles.

Vehicle Selection for Cost Analysis

Different models of the three types of equipment were chosen (table 1). The particular models ofdiesel equipment chosen for this study were representative of the basic types of permissible andnonpermissible mining equipment typically used in underground coal, metal, and nonmetalmines. Two coal haulers, common in coal mines that use diesel haulage, were selected as theCategory A, permissible vehicles. Six heavy-duty nonpermissible vehicles, all LHDs made byone manufacturer, were selected because they represent the broad range of equipment sizes thatoccur in this category of equipment in underground metal and nonmetal mines. Two utility

vehicles made by Getman Corporation were selected to represent typical light-duty,nonpermissible vehicles. The Getman vehicles are typical in their class, are widely used inunderground mines, and the authors have experience with the emissions and PM-emissioncontrols for this particular type of equipment.

Selection of PM-Emission Controls

The following factors were considered in selecting which emissions controls would be comparedwithin this study:

1. The amount of PM reductions that could be realistically expected in the field2. The current level of usage of a particular technology for PM-control in underground mines

3. The types of vehicles that the PM-control could be used with4. The availability of data pertinent to practical use and effectiveness of the emissions control

strategy in underground mines

Included in table 1 are the current or near-term emissions control strategies considered for eachvehicle, excluding the use of biodiesel fuels or blends.

The following four PM-emissions controls were selected:

DDEF: Currently used on for Category A equipment.

CDPF: Currently used on heavy-duty nonpermissible equipment.

DOC: Currently widely used on heavy-duty and light-duty nonpermissible equipment. Forthese analyses, it was assumed that DOCs would always be used with biodiesel or biodieselblends.

RFC-DPF: For light-duty vehicles. This new type of filter is under development and couldbe available for mine applications within five years.

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Equipment Engines After-

treatment

Type OEM Model Vehicle

Classification

OEM Model Displace-

ment (in3

)

Power

(b.h.p.)

Options

LHD Wagner ST2D Heavy-duty,Nonpermissible

Deutz F6L-

912W345 82

CDPF, DOC

LHD Wagner ST6C Heavy-duty,

Nonpermissible

Deutz F10L-

413FW973 231

CDPF, DOC

LHD Wagner ST6C (opt.) Heavy-duty,

Nonpermissible

DDC 6043-

GK32

Series 50

519 250

CDPF, DOC

LHD Wagner ST8B Heavy-duty,

Nonpermissible

DDC 6063-

GK32

Series 60

677 325

CDPF, DOC

LHD Wagner ST8B (opt.) Heavy-duty,

Nonpermissible

Deutz F12L-

413FW1168 277

CDPF, DOC

LHD Wagner ST15Z Heavy-duty,

Nonpermissible

DDC 6063-

GK32Series 60

775 475

CDPF, DOC

Utility Getman 576 - 6 pass. Light-duty,

Nonpermissible

Isuzu C240 146 57

RFC-DPF,DOC

Utility Getman 576 - 9 pass. Light-duty,Nonpermissible

Isuzu 4BD1 238 79

RFC-DPF,DOC

CoalHauler

Jefferey 4110Ramcar

Category A MWM 916-6 380 94 Waterscrubber,

DDEFDry system

CoalHauler

Jefferey 4114Ramcar

Category ACaterpillar

3306

PCNA641 146 Water

scrubber,

DDEFDry system

Table 1: Equipment identified for the life-cycle cost analysis, and exhaust

aftertreatment options considered for each classification and type of diesel equipment.

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PM-Emission Control Strategies for the Equipment Life-Cycle Analysis

Each of the three general types of vehicles and the emissions controls selected for this study arediscussed below. The assumptions made for the equipment life cycle analysis are also listed.

Biodiesel Fuel and Fuel Blends (Category A Equipment): Laboratory testing at the CDRhas shown that VOC from biodiesel fuel usage is largely (>70%) removed within the waterscrubber of Category A diesel engine power-packs used for underground coal mineapplications. Therefore, the use of a DOC in these types of applications is not necessary andwould not result in further PM reductions over the use of biodiesel fuels with an exhaustwater scrubber alone (McDonald and Spears). PM reductions exceeding 50% (compared topetroleum diesel fuel) were observed during laboratory testing of neat biodiesel fuel using aCategory A diesel engine power-pack incorporating a water scrubber (McDonald andSpears). Only power-packs with naturally aspirated, IDI diesel engine have been certified byMSHA to date. These IDI engines offer the ability to use biodiesel blend ratios of up to100% (neat) biodiesel with only minimal modifications to fuel system components.

i

Representative Category A diesel equipment evaluated for this study with biodiesel

fuel and fuel blends (no DOC):Make of vehicle: Jeffrey 4110 and 4114 RamcarsVehicle life: 8 yearsNumber of hours vehicle used per year: 3900Biodiesel cost: $1.50 to $3.00 / gallonBiodiesel blend levels with low-sulfurpetroleum diesel fuel

30%, 50%, 100%(limited analysis also performed with acontinuously variable 0-100% blend ratio)

Particulate reduction: 70%

Capital costs: (no significant difference in economic modelcompared to the uncontrolled case)

Labor costs: (no significant difference in economic modelcompared to the uncontrolled case)

Design cost: (no significant difference in economic modelcompared to the uncontrolled case)

Installation cost: (no significant difference in economic modelcompared to the uncontrolled case)

Fuel consumption: 6.2 or 7.5 gal/ hour.(McDonald and Spears)

DDEFs (Category A): The disposable diesel exhaust filter, designed to be used with a waterscrubber has been used as a PM-control in underground coal mines for about 5 years. Data isavailable on its performance, and PM reductions exceeding 90 % can be expected usingDDEFs.

Representative Category A diesel equipment evaluated for this study with DDEFs:

i Replacement of incompatible elastomers in soft fuel-lines and some fuel pump seals.

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Make of vehicle: Jeffrey 4110 and 4114 RamcarsVehicle life: 8 yearsNumber of hours vehicle used per year: 3900Life of DDEF: 3000 hours for the housing. The filter needs

replacement every shift for the 4114, and every 3

shifts for the 4110.Particulate reduction: 90%Capital costs: The capital cost for the housing was $5100-

$5600. Filter cost $45 each.Labor costs: $41.44/hour for design time, $23.04/hour for

installation and maintenance.Design cost: Labor cost of 16 hours @ 41.44/hour = $663Installation cost: Labor cost of 16 hours @ 23.05/hour plus $50

materials cost = $419Maintenance cost for housing: 10 hours over life of housing @ $23.05/hour /

3000 hrs = $.08/hour.

Fuel consumption: 5.4 or 6.5 gal/ hour.(Ambs, et al, 1994)

DOC with Biodiesel Fuel and Fuel Blends (Heavy-duty Nonpermissible Equipment): Neatbiodiesel fuel has been tested extensively with heavy-duty engines typical of undergroundmining applications by the USBM and CDR. Tests have included laboratory testing ofbiodiesel fuel and fuel blends with permissible and nonpermissible engine configurations,and field testing of an LHD in a large metal mining operation using neat biodiesel fuel.Laboratory testing has shown that significant PM reductions with biodiesel fuels innonpermissible applications require the use of a DOC for control of volatile organiccompounds (VOC) that contribute to the formation of condensed and adsorbed organic PM.

Reductions in PM-emissions exceeding 70% were observed during field testing of neatbiodiesel fuel with a DOC (McDonald et al. 1997). The majority of equipment in this marketsegment utilize engines with IDI combustion systems.

Representative heavy-duty nonpermissible vehicles evaluated for this study with

Biodiesel and a DOCMake of vehicle: Wagner 2-15 yd

3LHDs

Vehicle life: 8 yearsNumber of hours vehicle used per year: 3500Biodiesel cost: $1.50 to $3.00 / gallonBiodiesel blend levels with low-sulfur

petroleum diesel fuel

30%, 50%, 70%, 100%

(limited analysis also performed with acontinuously variable 0-100% blend ratio)

Life of DOC: 9000 hoursParticulate reduction: 70%Capital costs (DOC): The average of 3 prices for DOCs sized for each

vehicle, from three suppliers, for each specificapplication.

Labor costs (DOC): $30.38/hour for design time, $18.85/hour for

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installation and maintenance.Design cost (DOC): Metal: Labor cost of 10 hours @ 30.38/hour =

$304Installation cost (DOC): Labor cost of 10 hours @ 18.85/hour plus $50

materials cost = $239

Maintenance cost (DOC): 20 hours over life of DOC @ $18.85/hour / 9000hrs = $0.04/hour

Fuel consumption: 4.2-17.3 gal/ hour, depending on the vehicle.100% biodiesel with a DOC (McDonald et al. 1997)

CDPFs (Heavy-Duty Nonpermissible Equipment): The catalyzed ceramic filter has beenused on nonpermissible heavy-duty equipment for a number of years. It was chosen for

evaluation because its currently available, data is available on its performance, and PMreductions of 70% or greater can be expected when this device is used for an appropriatelyselected application.

Representative heavy-duty nonpermissible vehicles evaluated for this study withCDPFs:Make of vehicle: Wagner 2-15 yd3LHDsVehicle life: 8 yearsNumber of hours vehicle used per year: 3500Life of CDPF: 3000 hoursParticulate reduction: 70%Capital costs: The average of 2 prices for CDPFs sized for each

vehicle, from two suppliers.Labor costs: $30.38/hour for design time, $18.85/hour for

installation and maintenance.

Design cost: Labor cost of 10 hours @ 30.38/hour = $304Installation cost: Labor cost of 10 hours @ 18.85/hour plus $50

materials cost = $239Maintenance cost: 20 hours over life of CDPF @ $18.85/hour/3000

hrs = $0.13/hourFuel consumption: 3.7-15.1 gal/ hour, depending on the vehicle.(Watts, et al, 1995)

DOC with Biodiesel Fuel and Fuel Blends (Light-duty Nonpermissible Equipment):Light-duty, nonpermissible equipment predominantly utilizes IDI diesel engines, allowing the useof high-percentage blend ratios of biodiesel fuel. Although no testing of biodiesel with these

particular engines has occurred to date, biodiesel fuel and fuel blends have been tested withheavy-duty, high-speed IDI diesel engines with similar fuel and combustion systems(McDonald et al. 1995, Purcell et al.). Emissions results for the high-speed, light-duty IDIengines were generally comparable to laboratory emissions test results for heavy-duty IDIdiesel engines.

Representative light-duty nonpermissible vehicles evaluated for this study with

Biodiesel and a DOC:

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Make of vehicle: Getman 6- and 9-passenger utility vehiclesVehicle life: 12 yearsNumber of hours vehicle used per year: 1500Biodiesel cost: $1.50 to $3.00 / gallonBiodiesel blend levels with low-sulfur

petroleum diesel fuel

30%, 50%, 100%

(limited analysis also performed with acontinuously variable 0-100% blend ratio)

Life of DOC: 9000 hoursParticulate reduction: 70%Capital costs (DOC): The average of 3 prices for DOCs sized for each

vehicle, from three suppliers, for each specificapplication.

Labor costs (DOC): Metal: $30.38/hour for design time, $18.85/hourfor installation and maintenance.Coal: $41.44/hour for design time, $23.04/hourfor installation and maintenance.

Design cost (DOC): Metal: Labor cost of 10 hours @ 30.38/hour =$304Coal: Labor cost of 10 hours @ 41.44/hour =$414

Installation cost (DOC): Metal: Labor cost of 10 hours @ 18.85/hour plus$50 materials cost = $239Coal: Labor cost of 10 hours @ 23.05/hour plus$50 materials cost = $281

Maintenance cost: 20 hours over life of DOC @ $18.85/hour x 9000hrs = $0..04/hour

Fuel consumption: 2.1 or 2.9 gal/hour.

100% biodiesel with a DOC (McDonald et al. 1997)

RFC-DPFs (Light-duty, Nonpermissible Equipment):The NBB requested the inclusion onenew PM-emissions control technology in order to include comparison with an emergingtechnology as part of this study. The RFC-DPF was selected as a new PM-emission controlstrategy for comparison in this study because it presently is the only option, besides the useof DOCs, available for light-duty, nonpermissible, diesel-powered, underground miningequipment. It has been evaluated previously using light-duty diesel-powered forklifts inenclosed warehouses in Germany. A prototype system for use with light-dutynonpermissible diesel mining equipment is currently under development. The authors havesome experience evaluating this device on a mine utility vehicle, and have some data on PM

reductions using this device. Little is known about its long-term durability of the RFC-DPMif used underground. Durability of the device was conservatively estimated from durabilitydata of this device in forklift applications.

Representative light-duty nonpermissible vehicles evaluated for this study with RFC-

DPFs:

Make of vehicle: Getman 6- and 9-passenger utility vehiclesVehicle life: 12 years

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Number of hours vehicle used per year: 1500Life of RFC-DPF: 3000 hoursParticulate reduction: 65%Capital costs: The price for one RFC-DPF, sized for each

vehicle, from the lone supplier.

Labor costs: $30.38/hour for design time, $18.85/hour forinstallation and maintenance.

Design cost: Labor cost of 40 hours @ 30.38/hour = $1215Installation cost: Labor cost of 24 hours @ 18.85/hour plus $100

materials cost = $552Maintenance cost: 150 hours over life of RFC-DPF @ $18.85/hour x

3000 hrs = $0.94/hourFuel consumption: 1.8 or 2.5 gal/ hour.(Bickel and Taubert)

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Results from Equipment Life Cycle Cost Analysis

Table 2 summarizes the results of the life cycle analyses. It gives the costs for the competingPM-emissions controls, including 3 blends of biodiesel fuels, over the life of the machine. Thecost is not discounted, and the cost for biodiesel does not include the cost for diesel fuel that the

machine would have used if emissions controls were used.

Vehicle Vehiclelife (yrs)

Vehicleuse

(hrs/yr)

Emission controlstrategy

Biodieselblend level

(%)

DOC cost DOC andbiodiesel cost(biodiesel @

$1.50/gal)

DOC andbiodiesel cost(biodiesel @

$3.00/gal)

Emissioncontrol (filter)

cost

ST2D 8 3500 Biodiesel/DOC 30% $6,756 $34,000 $83,000 na

Biodiesel/DOC 50% $6,756 $55,000 $138,000 na

Biodiesel/DOC 100% $6,756 $111,000 $289,000 na

CDPF na na $63,000

ST6C 8 3500 Biodiesel/DOC 30% $11,053 $75,000 $189,000 na

Biodiesel/DOC 50% $11,053 $123,000 $320,000 na

Biodiesel/DOC 100% $11,053 $255,000 $675,000 na

CDPF na na $76,000

ST6C (opt.) 8 3500 Biodiesel/DOC 30% $11,053 $104,000 $271,000 naBiodiesel/DOC 50% $11,053 $175,000 $462,000 na

Biodiesel/DOC 100% $11,053 $368,000 $981,000 na

CDPF na na $120,000

ST8B 8 3500 Biodiesel/DOC 30% $11,660 $122,000 $321,000 na

Biodiesel/DOC 50% $11,660 $207,000 $547,000 na

Biodiesel/DOC 100% $11,660 $436,000 $1,165,000 na

CDPF na na $190,000

ST8B (opt.) 8 3500 Biodiesel/DOC 30% $11,660 $75,000 $190,000 na

Biodiesel/DOC 50% $11,660 $124,000 $320,000 na

Biodiesel/DOC 100% $11,660 $256,000 $676,000 na

CDPF na na $120,000

ST15Z 8 3500 Biodiesel/DOC 30% $15,808 $118,000 $302,000 na

Biodiesel/DOC 50% $15,808 $197,000 $513,000 na

Biodiesel/DOC 100% $15,808 $409,000 $1,085,000 naCDPF na na $191,000

Getman 12 1500 Biodiesel/DOC 30% $3,527 $12,000 $27,000 na

575 - 6 pass. Biodiesel/DOC 50% $3,527 $18,000 $45,000 na

Biodiesel/DOC 100% $3,527 $36,000 $92,000 na

RFC-DPF na na $60,000

Getman 12 1500 Biodiesel/DOC 30% $3,527 $15,000 $36,000 na

575 - 9 pass. Biodiesel/DOC 50% $3,527 $24,000 $61,000 na

Biodiesel/DOC 100% $3,527 $49,000 $126,000 na

RFC-DPF na na $66,000

Jeffrey 8 3900 Biodiesel1 30% na $44,000 $123,000 na

4110 Biodiesel1

50% na $78,000 $214,000 na

Biodiesel1 100% na $169,000 $459,000 na

DDEF na na $114,000

Jeffrey 8 3900 Biodiesel1 30% na $53,000 $148,000 na

4114 Biodiesel1 50% na $94,000 $257,000 na

Biodiesel1

100% na $203,000 $553,000 na

DDEF na na $208,0001DOC not required due to presence of water scrubber

Table 2: Summary of vehicle life cycle costs for emission controls and biodiesel fuel with

DOCs

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Category A Diesel Equipment: Two ramcars were evaluated. The cost for using DDEFs on thesmaller ramcar was $114,000, while neat biodiesel at $1.50/gal cost about $172,000. On thelarger machine, however, the cost for using DDEFs and neat biodiesel (at $1.50/gal) wasvirtually identical. The disposable filter needs to replaced once every three shifts on the smallermachine, and once per shift on the larger ramcar. This accounts for the significant cost

difference between the two machines.

Heavy-duty Nonpermissible Diesel Equipment: The costs for using CDPFs on these machinesranged from $63,000 to $191,000, depending on the size of the machine. With biodiesel at a costof $3.00/gal, the cost of neat biodiesel and blends was higher than the cost for CDPFs in eachinstance. With biodiesel at $1.50/gal, the cost of neat biodiesel was higher than the cost ofCDPFs by a factor of two or more, except for the smallest machine. The ambient PM reductionsin an underground mine using CDPFs and neat biodiesel are estimated to be comparable atapproximately 70%. From a strictly cost standpoint, biodiesel does not look like a goodalternative for PM-control on this type of equipment.

Light-duty Nonpermissible Diesel Equipment: Biodiesel appears to be a better alternative tofilters on this class of equipment. The cost for using RFC-DPFs exceeded $60,000 for eachmachine, and exceeded the cost for neat biodiesel, with biodiesel at $1.50/gal. The ambient PMreduction using neat biodiesel fuel is also projected to be better, at 73% versus, 65% using RFC-

DPFs.

Note from the Authors: A brief comparison of the capitol and operating costs of using electric

versus diesel underground coal mining equipment for coal haulage is given in Appendix I.

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VI. Methods of Conducting Discounted Cost Analyses of an Underground

Coal Mine and an Underground Metal Mine

Background

The expected fuel and emissions controls costs for a mines vehicle fleet over the operating lifeof the mine must be estimated if competing emission control strategies are to be accuratelycompared. The expected reductions in ambient PM concentrations in the mine using differentemissions control strategies must also be considered. A case study of a coal mine and a metalmine was developed in order to compare the costs for using competing emission controls(DDEFs, CDPFs, and RFC-DPFs) to biodiesel fuels and fuel blends. For the initial analysis, itwas assumed that the mines would choose to use the emissions controls on all their machines.The comparisons in this case would be between the use of biodiesel (with a DOC innonpermissible cases) in their entire fleet or the competing exhaust aftertreatment devices in theentire fleet.

Mining can occur over relatively long periods of time, and it was assumed that the methodsselected (filters or biodiesel) would be used over the life of the mine. Costs associated withalternative technologies can be compared by discounting the annual expenditures over the life ofthe mine. In this way, the timing as well as the magnitude of expenses can be fairly considered.The basic assumption behind the use of discounting is that it is preferable to accept incomesooner and defer expenditures to later periods, whenever possible. The net present valuerepresents the worth of one or more payments in the future to a mining company today, given theexpected interest or discount rate available. The selection of an appropriate discount or interestrate reflects this notion and helps measure the net present value of competing choices of flows ofrevenues and expenditures. For example, which choice is superior if a firms discount rate is12%?

1) Accept $1,000.00 today, or2) Accept $3,000.00 ten years from today

Answer: $1,000.00 today is superior. The $3,000 to be received in ten years must bediscounted to its present value. The formulas for the computations appear below:

Present Value = (1+ r)-n (where r =discount rate, n = periods)

Present Value = (1.12)-10 x $3,000

Present Value = 0.3219732 x $3,000

Present Value = $965.92 (Therefore, it is better to receive $1,000 today.)

Present value discounting was used throughout the coal and metal mine analyses to fairlyconsider both the timing and magnitude of expenditures over the life of the operations.

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Selection of Case Study Mines

MSHA has obtained data from some metal and all coal mines throughout the United Statesrelated to the use of diesel-powered equipment at individual mines. The data includes all of the

diesel-powered vehicles at a mine, the type and/or make of the vehicles, the engines used inthem, and the type of MSHA certification or approval given to the machine.

A case study coal mine and a metal mine were selected after reviewing over 100 sets of datafrom individual mines. The mine equipment populations were selected based on three criteria;

1) A mine of moderate size: Both mines chosen had production levels of about500,000 short tons of ore or coal per year. The metal mine had 40 diesel vehicles,the coal mine had 25 vehicles and one generator.2) Completeness of data: The data on the vehicles and engines for both casestudy mines was virtually complete. Few assumptions on the size and type ofengines used had to be made.

3) Type of equipment and engines: Some of the of the vehicles used at the casestudy mines were the vehicles evaluated during the equipment life cycle analysis.

Data on the mine vehicle equipment populations are given in Tables 3 and 4. The PM-emissionscontrol strategy for each type of machine is given. The types of emission controls evaluated, andthe assumptions made for the evaluation, are the same as those made for the equipment life cycleanalysis described above.

The life of the vehicles chosen varied from 8-12 years. A mine life of 24 years was assumed, sothat the vehicles were replaced 1 or two times over the mineslife. It was assumed that eachmine operated 2 10-hour shifts, five days a week, 52 weeks per year.

Type of DieselEquipment

Capacity HP Numberof

vehicles

Vehicle life(yrs)

Hours ofoperation/yr

Diesel fueluse/vehicle

(gal/hr)

EmissionControl

LHD 8 yd 277 3 8 3500 8.3 CDPFLHD 6 yd 231 5 8 3500 6.9 CDPF

Haul Truck 26 T 271 6 8 3900 8 CDPFRoof Tower na 186 2 10 2200 5.6 CDPF

Grader na 95 1 10 2400 2.8 CDPFDrill Jumbo na 82 9 10 2300 2.5 CDPFRoof Bolter na 82 1 9 3000 2.5 CDPFLube truck na 82 1 12 1500 2.5 RFC-DPF

Scaler na 82 1 12 1500 2.5 RFC-DPFService vehicles na 82 4 12 1500 2.5 RFC-DPF

Tractor na 52(ave) 7 10 2100 1.6 RFC-DPF

Table 3: Case study metal mine: equipment list, emission controls and

fuel use

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Type ofDiesel

Equipment

Capacity HP Number ofvehicles

Vehicle life(yrs)

Hours ofoperation/yr

Diesel fueluse/vehicle

(gal/hr)

EmissionControl

Ramcar 14 T 150 5 8 3900 6.5 DDEF

Coal scoop 5 T 150 2 8 3900 4.5 DDEF

LHD 1/2 yd 42 2 8 1000 1.3 RFC-DPFGenerator 200 kw 285 1 12 3000 14.8 na

Personnelcarrier

6-pass 57 2 12 1500 1.7 RFC-DPF

Lube truck na 82 3 12 1500 2.5 RFC-DPF

Crane truck na 82 2 12 1500 2.5 RFC-DPF

Forklift na 82 1 12 1600 2.5 RFC-DPF

Utility truck na 57 6 12 1500 1.7 RFC-DPF

Grader na 56 1 10 2400 1.7 RFC-DPF

Welder na 55 1 12 1400 1.7 RFC-DPF

Tractor na 16 2 10 2100 0.5 RFC-DPF

Table 4: Case study coal mine: equipment list, emission controls, and fuel use

Methods of Analysis

The discounted cost analyses were conducted using standard spreadsheet software. Fourspreadsheets were constructed for the following situations: Metal mine using biodiesel with DOCs Metal mine using filters Coal mines using biodiesel with DOCs Coal mines using filters

All the data for each type of diesel-powered equipment were entered into separate categorieswithin each spreadsheet model. Each spreadsheet also contained a summary of the data for the

entire vehicle population at that mine. Categories within each spreadsheet included the costsassociated with the operation of each machine along with the year when the expenditure would

occur. The following possible cost items were considered and discounted over the life of themine: Capital cost of the PM-emissions control Design labor cost Installation parts and labor Maintenance parts and labor Replacement costs for emissions controls Fuel Costs (for diesel fuel or biodiesel and biodiesel/diesel blends) Cost for lost production (coal mine using DDEFs only)

An example of one spreadsheet for a Ramcar using DDEFs is given in Table 5.

In addition, the expected PM-emissions from each vehicle, and the expected reduction inambient PM due to the use of the competing PM-control strategies for the entire fleet, werecalculated.

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Table 5: Example of a spreadsheet for a ram-car using DDEFs.

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Data Analysis

The spreadsheets were constructed so that a number of variables could be changed, and thediscounted cost for each of the PM-control scenarios over the life of the mine could then be

calculated to determine the relative effects of the changes.

This allowed the testing of numerous sets of assumptions in order to obtain a good understandingof the costs of reducing ambient PM concentrations in underground mines.

The discounted total cost for PM-emissions control over the life of the mine for the minesdiesel fleet under assumed conditions was the primary result summarized within eachspreadsheet. This is the discounted cost for additional fuel consumed and emissions controlcosts, over and above the standard fuel costs using low sulfur, petroleum fuel. Other datasummarized within the spreadsheets included the following:

Yearly fuel consumption for each type of diesel-powered equipment Fuel costs, nominal and discounted, for each type of equipment Projected reduction in ambient PM concentrations achieved for each combination of

diesel equipment and relevant PM-emission control strategy Nominal and discounted emissions control costs for each combination of diesel

equipment and relevant PM-emission control strategy

Table 6 gives an example of a data summary for a metal mine using biodiesel with DOCs.

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Table 6: Example of a summary spread-sheet for the case-study metal mine using biodiesel

with DOCs.

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VII. Results from Metal Mine Discounted Cost Analysis

Sensitivity Analysis

Table 7 gives discounted costs over the life of the coal mine, and the expected PM reduction for

biodiesel versus the competing PM-emissions control strategies for 18 combinations of discountrates, blend levels, and biodiesel costs. The discounted emissions control and fuel costs rangedfrom $2,343,000 to $2,941,000 for mines with fleets of equipment using the CDPFs (heavy-duty)and RFC-DPFs (light-duty). By comparison the discounted emissions control and fuel costs forbiodiesel with a DOC ranged from $1,419,000 to $11,498,000. The broad range of costs forbiodiesel reflects the effects of blends from 30% to 100% and biodiesel prices from $1.50 to$3.00 .

The reduction in ambient PM concentrations using CDPFs and RFC-DPFs was 69 %. Theambient PM reduction using biodiesel fuel blends ranged from 22 to 73 %, depending on theblend ratio.

Combination of

Variables Selected

Competing Emission

Controls

Biodiesel Fuel

Discountrate (%)

Biodieselcost ($/gal)


(%)

Disc. emissioncontrol and

additional fuelcost

Particulatereduction with

emissioncontrols

Disc. DOCand additional

fuel cost

Particulatereduction withBiodiesel and

DOCs

12% $1.50 30% $2,941,000 69% $1,419,000 22%

12% $1.50 50% $2,941,000 69% $2,237,000 37%

12% $1.50 100% $2,941,000 69% $4,452,000 73%

12% $3.00 30% $2,941,000 69% $3,341,000 22%

12% $3.00 50% $2,941,000 69% $5,531,000 37%

12% $3.00 100% $2,941,000 69% $11,498,000 73%

14% $1.50 30% $2,609,000 69% $1,252,000 22%14% $1.50 50% $2,609,000 69% $1,970,000 37%

14% $1.50 100% $2,609,000 69% $3,915,000 73%

14% $3.00 30% $2,609,000 69% $2,939,000 22%

14% $3.00 50% $2,609,000 69% $4,862,000 37%

14% $3.00 100% $2,609,000 69% $10,102,000 73%

16% $1.50 30% $2,343,000 69% $1,117,000 22%

16% $1.50 50% $2,343,000 69% $1,755,000 37%

16% $1.50 100% $2,343,000 69% $3,483,000 73%

16% $3.00 30% $2,343,000 69% $2,616,000 22%

16% $3.00 50% $2,343,000 69% $4,325,000 37%

16% $3.00 100% $2,343,000 69% $8,980,000 73%

Table 7: Metal mine - combinations of discount rate, biodiesel cost, and

blend level

Effect of Discount Rates

Discount rates of 12%, 14%, and 16% were tested. Because mining is considered a riskyenterprise, higher threshold rates are required to recruit investment than into some othereconomic activities with more predictable flows of income (economic studies of oil explorationhave frequently used discount rates of 18%). Varying discount rates from 12% to 16% for neatbiodiesel at a price of $1.50/gal resulted in discounted total costs that vary from $4,452,000 to

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$3,483,000. The discounted costs of using neat biodiesel were approximately 50% higher thanthose achieved using CDPFs and RFC-DPFs. The discounted total costs are not particularlysensitive across this range of discount rates because of the long life of mine and the coststructure of the two competing PM-control strategies. As a result, a discount rate of 14 % wasselected for further analyses.

Effect of Blend Levels and Biodiesel Cost

One of the advantages of biodiesel is that a specific blend level could be selected to achievespecific target levels of ambient PM concentrations. The effect of blend levels on ambient PMconcentrations in the mine can be seen in Figure 1. PM reductions of 69% can be achieved whenthe entire complement of vehicles use CDPFs and RFC-DPFs. This same level of PM reductioncould be accomplished by using a biodiesel blend level of 94%.

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80 90 100

Biodiese l Blend Level (%)

ReductioninambientPM

concentration

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

Dis

counted

biodieselandDOCcost/ton

Particulate Reduction %

Disc.Cost/ T.

Figure 1: Metal mine: blend level versus reduction in ambient PM concentration and

discounted biodiesel and DOC cost/short ton of ore produced.

Initially, prices of $1.50 and $3.00 per gallon were tested for biodiesel. At $3.00 per gallon, thediscounted fuel cost of 100% blend would vary from $8,980,000 to $11,498,000, dependingupon the discount rate. At $1.50 price for biodiesel, a 100 % blend varied from $3,483,000 to$4,452,000. The discounted cost for using CDPFs and RFC-DPFs was under $3,000,000 in eachcase. Further analysis revealed that biodiesel would have to be priced at $1.18/gal to equal thecost of CDPFs and RFC-DPFs, assuming a 14 % discount rate and that neat biodiesel fuel at

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VIII. Results from Coal Mine Discounted Cost Analysis

Sensitivity Analysis

A discussion of results that is similar to the metal mine case follows, with two exceptions. The

coal mine equipment population contained a generator that burned a large amount of fuel. It wasassumed that the mine would use a DOC on the generator, and that the generator could burn100% biodiesel. In addition, the use of DDEFs on coal production equipment could adverselyimpact production when a mine is working at or close to capacity. The cost of lost productionwas estimated for the situation of a coal mine using DDEFs.

Table 9 gives discounted costs and the expected ambient PM reduction for using biodiesel fuelversus DDEFs (heavy-duty) and RFC-DPFs (light-duty) for 18 combinations of discount rates,blend levels, and biodiesel costs. The discounted costs for fuel and PM reduction ranged from$1,538,000 to $1,942,000 for mines with equipment using DDEFs and RFC-DPFs. Thediscounted biodiesel costs ranged from $497,000 to $5,593,000. The broad range of costs for

biodiesel reflects the effects of blends from 30% to 100% and also biodiesel prices from $1.50 to$3.00 .

Combination of

Variables Selected

Competing Emission

Controls

Biodiesel Fuel

Discountrate (%)

Biodieselcost ($/gal)


(%)

Disc. emissioncontrol and

additional fuelcost

Particulatereduction with

emissioncontrols

Disc. DOCand additional

fuel cost

Particulatereduction withBiodiesel and

DOCs

12% $1.50 30% $1,942,000 73% $631,000 22%

12% $1.50 50% $1,942,000 73% $1,034,000 37%

12% $1.50 100% $1,942,000 73% $2,124,000 73%

12% $3.00 30% $1,942,000 73% $1,577,000 22%12% $3.00 50% $1,942,000 73% $2,655,000 37%

12% $3.00 100% $1,942,000 73% $5,593,000 73%

14% $1.50 30% $1,718,000 73% $557,000 22%

14% $1.50 50% $1,718,000 73% $910,000 37%

14% $1.50 100% $1,718,000 73% $1,868,000 73%

14% $3.00 30% $1,718,000 73% $1,388,000 22%

14% $3.00 50% $1,718,000 73% $2,334,000 37%

14% $3.00 100% $1,718,000 73% $4,914,000 73%

16% $1.50 30% $1,538,000 73% $497,000 22%

16% $1.50 50% $1,538,000 73% $811,000 37%

16% $1.50 100% $1,538,000 73% $1,662,000 73%

16% $3.00 30% $1,538,000 73% $1,235,000 22%

16% $3.00 50% $1,538,000 73% $2,076,000 37%

16% $3.00 100% $1,538,000 73% $4,368,000 73%

Table 9: Coal mine - combinations of discount rate, biodiesel cost, and

blend level

The reduction in ambient PM concentrations using DDEFs and RFC-DPFs was 73 %, and thePM reduction using biodiesel fuel blends ranged from 22 to 73 %, depending on the fuel blendratio.

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Effect of Discount Rate

Discount rates of 12%, 14% and 16% were tested. Varying discount rates for 100% biodiesel at$1.50/gal result in total discounted costs that vary from $2,124,000 to $1,662,000. The totaldiscounted costs of using the neat biodiesel option were approximately 10% higher than usingDDEFs and RFC-DPFs . Discounted total costs are not particularly sensitive across this range of

discount rates because of the long life of mine used and the cost structure of the competingtechnologies. Consequently, 14% was the discount rate used for further analyses.

Effect of Blend Level and Biodiesel Cost

Blend levels of 30%, 50% and 100% biodiesel were used as model inputs. An estimatedreduction in ambient PM concentrations of approximately 70% can be achieved using 100%biodiesel or using DDEFs and RFC-DPFs. Figure 2 shows the level of PM reduction and

discounted cost per ton using biodiesel with DOCs. Because these levels of PM reduction arealmost equivalent, the blend level of 100% for biodiesel allows a convenient cost comparison ofthe fuel to the cost of DDEFs and RFC-DPFs at the same level of performance.

At $3.00 per gallon, the discounted fuel cost of neat biodiesel would vary from $4,368,000 to$5,593,000, depending upon the discount rate. At $1.50 price for biodiesel, the cost would varyfrom $1,662,000 to $2,124,000. The discounted cost of using DDEFs and RFC-DPFs wouldvary from $1,538,000 to $1,942,000.

Effect of Mine Life

Assuming a six year life for the coal mine, DDEFs and RFC-DPFs represent a less costlyapproach to achieving ambient PM reductions in the mine. The costs would be about 8% higherusing biodiesel to achieve the same level (70%) of PM reductions as DDEFs and RFC-DPFs.This is a similar to the result for the 24 year mine life, and indicates that the life of the mine haslittle effect on the cost of the two different methods.

Effect of Targeting Category A Diesel Equipment

Coal mine operators might consider using either biodiesel or DDEFs on the Category Amachines only. In this coal mine they are the ramcars and coal scoops. The use of biodieselwould result in ambient PM reductions of approximately 47%, at a discounted cost of $1,133,000(table 10). If mine operators were to use DDEFs on permissible machines, they would achievePM reductions of 60%, at a discounted cost of $1,042,000.

Effect of Targeting Light-duty (Nonpermissible) Diesel Equipment

As in the metal mine case, biodiesel was found to be cheaper than RFC-DPFs on light-dutyvehicles. Biodiesel would cost $708,000, and would result in a ambient PM reduction of 22%.It would cost nearly as much ($676,000) to achieve a 13% reduction using RFC-DPFs. It wouldcost (present value) $53,000, on average, to buy a percentage point of ambient PM reductionwith RFC-DPFs and only $28,000 to buy a percentage point of PM reduction with the biodieseland DOCs.

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0

10

20

30

40

50

60

70

80

0 10 20 30 40 50 60 70 80 90 100

Biodiese l blend level (%)

ReductioninambientPM

concentration(%)

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

0.5

Discountedbiodieselan

dDOCcost/ton

Particulate Reduction %

Disc.Cost/ T.

Figure 2: Coal mine: blend level versus reduction in ambient PM concentration and

discounted biodiesel and DOC cost/short ton of ore produced.

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Reduction in ambient PMconcentrations(%)

Discounted cost over

life of mine

PM-control Strategy Exhaust

AftertreatmentPM-controls

Biodiesel Exhaust

Aftertreatment PM-controls

Biodiesel

Biodiesel (no DOC) on heavy-duty equipment

- 47 - $ 1,133,000

DDEFs used on heavy-duty

equipment60 - $ 1,042,000 -

Biodiesel and DOC on light-duty equipment

- 22 - $ 708,000

RFC-DPFs on light-dutyequipment 13 - $ 676,000 -

Table 10: Coal mine vehicle fleet PM reduction and discounted costs using neat biodiesel

vs. filters on heavy-duty and light-duty equipment over a 24 year life of the mine.

Effect of Lost Production (coal mine using DDEFs)

If one were to consider a coal mine operated with no excess production capacity (no idle labor orproduction equipment), then one could apply penalties for the reduced production due to timetaken to replace disposable filter elements on the permissible vehicles equipped with DDEFsystems.

The production lost due to the time necessary to change filters was calculated and cost penaltieswere derived based upon a mine mouth price for coal of $20.00/ ton. It was assumed that eachramcar would be idle between each ten hour shift, and each vehicles production would bereduced by one load of coal per day. This would result in 140 coal loads of production lost perramcar per year. The mines annual production would be reduced to 486,350 tons. The value ofthe coal production lost could be determined by multiplying the lost production by $10.00 perton ( mine mouth costs of $20/T minus $10.00 operating costs per ton), or $137,000 of lostproduction per year.

If the lost production is treated as a cost or penalty, the discounted cost of neat biodiesel and thediscounted cost using DDEFs would be equal at a biodiesel cost of $1.89/gallon, when demand is

greater than the mine capacity. Therefore, at biodiesel prices less than $1.89/gallon, mineoperators can use biodiesel more economically to reduce ambient PM concentrations than byusing petroleum based diesel fuel at $0.70/gallon with DDEFs.

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IX. Conclusions and Recommendations

Conclusions

The equipment life cycle analyses indicated the following:

Biodiesel at $3.00/gal was too expensive to use with Category A, heavy-dutynonpermissible, or light-duty nonpermissible mining equipment. Biodiesel in thisequipment market is not competitive strictly on the basis of cost with existing andexpected PM-control technologies.

Biodiesel at $1.50/gal was too expensive for heavy-duty nonpermissible equipment. Thecost for CDPFs was much lower than neat biodiesel. Blends of 30 and 50% biodieselwere less expensive in some instances, but gave much lower reductions in PM.

Biodiesel looks like a viable PM-control strategy compared to filter PM-control strategieson light-duty equipment. RFC-DPFs are relatively costly to buy, install and operate, andlight-duty equipment burns less fuel than heavy-duty. At $1.50/gal, the cost of burning

biodiesel was about 25-40% lower than using RFC-DPFs on the two utility vehiclesevaluated.

There was a large disparity in the cost of using DDEFs on the two ramcars, giving muchdifferent results when the cost of biodiesel is compared to using DDEFs. Biodiesel costsalmost one and one half times as much as DDEFs on the 10 ton hauler, while the costswere identical on the larger machine. Coal mines using the larger haulers may wish toseriously consider using biodiesel rather than DDEFs.

The equipment life cycle analyses indicated that biodiesel at $1.50/gal may be a viable PM-control strategy for light-duty nonpermissible equipment, and some types of Category Aequipment. It does not look competitive on heavy-duty nonpermissible equipment. The use of

exhaust filters for PM-control will result in ambient PM reductions exceeding 65%, and mineoperators would need to use neat biodiesel with DOCs to get comparable reductions.

The discounted cost analyses, where the cost for using biodiesel for the entire fleet of vehiclesat a coal

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