Donaldson, Robert (DEP) 

From: 

Sent: 

To: 

Subject: 

Leslie H. Witherspoon [Witherspoon_Leslie_H@solarturbines.com] 

Wednesday, June 23, 2004 3:09 PM 

Donaldson, Robert (DEP) 

Solar Turbines Comment Letter 

June 2004 Solar Mercury 50 

Turbines Comme... missions Signature. 

Please see attached . As you know we are ver y concerned wit h 

t he proposa l and it' s impact on our abilit y t o place produc t int o Mass. Our newest 

turbin e th e Mercury 50 i s a t 5 ppm NOx warrant y and would be unable t o meet the 

proposed standard withou t cogen o r SCR which jus t doesn't seem right . Especiall y since 

t he Mercury 50 i s a huge improvement over average Mass gri d emissions. Not al l DG 

application s have a steam host and an SCR would kil l most project s economically. 

Please consider th e level s i n Table 2 fo r gas turbine s so tha t th e million s o f dollar s 

spent over the las t decade i n R&D t o achieve singl e digi t NOx level s ( 5 ppm on the 

Mercury 50, 9 ppm targe t on othe r models) creates an opportunit y fo r dry-low-NOx gas 

turbine s (withou t SCR/CO) t o pla y i n DG markets. 

Thanks 

Lesli e 

(See attache d file : June 2004 Sola r Turbines Comment Letter.pdf ) 

(See attache d file : Mercury 50 Emissions Signature Versio n 3.pdf) 

1 
Solar Turbines Incorporated 

9330 Sky Park Court 

San Diego, CA 92123 

Tel: (858)694-1616 

June 23, 2004 

Submitted Electronically 

To: Bob Donaldson 

Massachusetts Department of Environmental Protection 

Bureau of Waste Prevention 

Business Compliance Division 

One Winter Street 

Boston, MA 02108 

Robert.Donaldson(a),state.ma.us 

From: Solar Turbines Incorporated 

Contact: Leslie Witherspoon 

9330 Sky Park Court 

MZ: SP3-Q 

San Diego, CA 92123-5398 

Phone: 858.694.6609 

Fax: 858.694.6715 

witherspoon leslie h@solarturbines.com 

Solar Turbines Incorporated (Solar) appreciates the opportunity to comment on the proposed 

amendments to 310 CMR 7.00 and 310 CMR 70.00. 

Solar is a manufacturer of industrial gas turbines [(1-14 MW (1,500 to 20,000 hp)]. Solar's fleet 

includes over 11,500 combustion turbines in over 90 countries. Our domestic fleet consists of 

approximately 5800 combustion turbines. For the past 30 years, Solar's industrial gas turbines 

have been used in a wide range of power generation and oil and gas applications. 

Solar does not support the proposed regulation revisions. Solar does not understand the 

motivation of the agency to mandate Lowest Achievable Emission Rate (LAER) levels on 1-10 

MW industrial gas turbines when federal Prevention of Significant Deterioration (PSD) or Nonattainment review is not triggered. The DEP should clarify to stakeholders and the public the 

need for prescriptive emission limits (that mandate very expensive add-on control equipment) 

rather than a top down technology review for smaller generators. 

i t mm • • 

Solar Turbines 

A Cmr0H C*mf*»f 

Caterpillar: Non-Confidential 
Specific Comments 

Solar has comments and recommendations on the following proposed regulation revisions. 

• Proposed NOx and CO Levels for Natural Gas Fired Gas Turbines 

• Proposed NOx and CO Levels for Liquid Fuel Gas Turbines 

• Proposed Ammonia Slip Level 

• Proposed Particulate Matter Category 

• Natural Gas "Definition" 

• Emissions Credit for Cogeneration 

• Certification Concept Concerns 

Proposed NOx and CO Levels for Natural Gas Fired Gas Turbines 

The department is proposing emission levels for natural gas fired gas turbines at 0.14 lb/MW-hr 

for NOx and 0.09 lb/MW-hr for CO. The proposed levels are extremely low for the <10MW size 

class of turbine and represent LAER levels for NOx and stricter-than-LAER levels for CO. 

In order to encourage the installation of clean, efficient natural gas fired cogeneration systems in 

the <10MW size class, Solar recommends that the department pace any required emission levels 

with dry-low-emissions (DLE) technology developments/advancements. Such a policy will 

encourage DLE technology development while supporting the concept of pollution prevention 

(vs. abatement technologies). Any need for add-on control should be evaluated and applied as 

required via the PSD and Non-attainment permitting programs. 

The required emission levels should reflect what is achievable by several manufacturers across 

typical operating and ambient temperature ranges. Lower emissions levels should only be 

evaluated on a case-by-case basis through the appropriate PSD/NA review. 

Solar recommends that the emission levels in Table 2 for NOx and CO be applicable to natural 

gas fired turbines an that Table 3 be deleted. 

Proposed NOx level for Combined Cycle Liquid Fuel Fired Gas Turbines 

The department is proposing emission levels for liquid fuel fired gas turbines at 0.34 lb/MW-hr 

for NOx and 0.18 lb/MW-hr for CO. The proposed levels are extremely low for the <10MW size 

class of turbine and represent stricter than LAER levels for NOx and CO. 

In order to encourage the installation of clean, efficient natural gas fired cogeneration systems in 

the <10MW size class, Solar recommends that the department pace the required emission levels 

for liquid fuel with DLE technology developments/advancements. Such a step will encourage 

DLE technology development while supporting the concept of pollution prevention (vs. 

abatement technologies). Any need for add-on control should be evaluated and applied as 

required via the PSD and Non-attainment permitting programs. 

The required emission levels should reflect what is achievable by several manufacturers across 

typical operating and ambient temperature ranges. Lower emissions levels should only be 

evaluated on a case-by-case basis through the appropriate PSD/NA review. 

Caterpillar: Non-Confidential 

Page 2 of 4 

Solar Turbines Comment Letter 
Because liquid fuel in turbines is primarily only used as a back-up fuel, Solar recommends that 

emission levels for liquid fuel be set at achievable dry-low-emission levels. 

Proposed Ammonia Slip Level 

MADEP is proposing an ammonia slip level of 2 ppm. While MADEP has had this policy for 

several years, the level adds unnecessary complexity and cost to the SCR system. The increased 

complexity and cost provides little or no measurable environmental benefit. A typical Best 

Available Control Technology (BACT) level for gas turbines is 5-10 ppm ammonia slip. 

Proposed Particulate Matter Category 

Solar suggests MADEP remove the particulate matter emissions level category for gas turbines 

from the proposed regulation. Whether or not to include particulate matter emissions for gas 

turbines was discussed at length during the RAP distributed generation model rule development 

process. After much discussion, consensus was reached that regulating particulate matter 

emissions from gas turbines is unnecessary. The decision was based on many facts including: 

natural gas fired gas turbines have negligible particulate emissions, the emissions that do exist are 

grossly over estimated by current EPA test methods, and if a gas turbine did not meet a given 

standard there is nothing that can be done to the turbine operation or with add-on control 

equipment to reduce measured emissions. 

What is the basis for the proposed emission level of 0.1 lb/MW-hr? Based on emission source 

test data we've seen, the proposed value is not representative of what small industrial gas turbines 

can achieve using current source test methods on liquid fuel. In fact, if MADEP looked at source 

test results from small gas turbines in the state on natural gas fuel you would find levels 3-4 times 

higher than the proposed liquid fuel level. The levels that we have seen from small turbines on 

liquid fuel are 4-7 times the proposed level. 

Natural Gas Definition 

In Table 3 of the May 2004 draft, the term "Gas" is used. Please change the term to "Natural 

Gas" as there are numerous gas fuels that can be burned in turbines that cannot be used in 

conjunction with DLE or add-on control systems. For example, gases such as landfill/digester 

must use diffusion flame combustion systems. 

Emissions Credit for Cogeneration 

Solar suggests MADEP adopt steam credit method similar to the simplified method Texas 

adopted in their distributed generation rulemaking process. Essentially waste heat is credited at 

3.413 MMBtu of waste heat per MW-hr. Special attention should be given as to how units will 

calculate waste heat (theoretical or actual/instantaneous or average) and how and when 

compliance with an output based standard will be achieved. 

Certification Concept Concerns 

Section 310 CMR 7.26(43)0b)(l) states that, "A supplier of an engine or turbine may seek to 

certify that an engine or turbine met the emission limitation..." Section 310 CMR 7.26(43)(e) 

states that, "Certification shall include a statement from the manufacturer that the installed engine 

or turbine is capable of complying with the emission limitations. 

Caterpillar: Non-Confidential 

Page 3 of 4 

Solar Turbines Comment Letter 
As similar rules have been developed in several states over the last few years the same 

"certification" concerns arise again and again. For example, in order to meet the proposed 

emission levels in Table 3, a typical 3-15 MW gas turbine would require some combination of 

cogeneration (fired/unfired), SCR, and CO oxidation catalyst. In such a situation the turbine, heat 

recovery steam generator, duct burners, SCR, and CO catalyst are provided by several vendors 

and assembled on site. Therefore "certification" in the historical sense, as with on-road engines, 

will not be done via a factory test. Prior to construction, compliance with the proposed limits can 

only be calculated for the system based on design parameters. Will this be sufficient for 

"certification" as MADEP envisions? 

For the vast majority of prime movers commercially available today, the "engine or turbine" 

alone is not capable of complying with the emission limitations. Thus, "manufacturer 

certification" is irrelevant. Please consider the situation described above as the Department 

develops the certification forms mentioned in the proposal. 

Caterpillar: Non-Confidential 

Page 4 of4 

Solar Turbines Comment Letter 
Mercury 50 Emissions Signature 

Solar Turbines 

i 
Contents 

Page 

INTRODUCTION 1 

EMISSIONS WARRANTIES - NOx, CO, AND UHC 1 

OTHER POLLUTANT EMISSIONS ESTIMATES 1 

COLD AMBIENT EMISSIONS ESTIMATES 2 

EMISSIONS ESTIMATES AT <50% LOAD 2 

START-UP EMISSIONS 3 

SHUTDOWN EMISSIONS 4 

COMMISSIONING EMISSIONS 4 

Caterpillar is a registered trademark of Caterpillar Inc. 

So/arand Mercury are trademarks of Solar Turbines Incorporated. 

Specifications subject to change without notice. Printed in U.S.A. 

© 2003 Solar Turbines Incorporated. All rights reserved. 

TPES/0504 
Mercury 50 Emissions Signature 

Leslie Witherspoon 

Environmental Program Manager 

INTRODUCTION 

The Advanced Turbine Systems (ATS) Program 

was initiated by the U.S. Department of Energy 

(DOE) in 1992 to produce 21st century gas 

turbines - systems that are more efficient, 

cleaner, and less expensive to operate than 

today's turbines. As part of the ATS program, 

Solar Turbines designed the MercuryTM 50 gas 

turbine. The Mercury 50 gas turbine incorporates 

many state-of-the-art combustion and materials 

technologies, resulting in an initial offering at 

4600 kW, 8863 Btu/kW-hr, and 38.5% efficiency 

(ISO conditions). 

The Mercury 50 is a "recuperated gas 

turbine" and is available in a gas-only configuration. The Mercury 50 incorporates an "Ultra-Lean 

Premix" (ULP) combustion system, which 

produces a very favorable emissions signature. 

This paper presents the Mercury 50's warrantable 

and expected emissions for several regulated 

pollutants and addresses other frequently 

requested air emissions related data. 

EMISSIONS WARRANTIES -

NOx, CO, AND UHC 

Emission warranties are available for nitrogen 

oxide (NOx), carbon monoxide (CO), and 

unburned hydrocarbons (UHC). Emission 

warranties are offered subject to express terms 

and conditions. Table 1 summarizes the lowest 

allowable emissions warranty for natural gas in 

ppmv (typical U.S. and Canadian units) and 

mg/nm3 (typical European unit). Emission 

warranties are only offered for steady-state conditions, at ambient temperatures between O^F and 

120°F, and are limited to 50-to-100% load on gas 

fuel. The emissions warranty expires simultaneously with the engine warranty. The customer can 

extend the warranty period by purchasing an 

extended warranty or a service program that 

includes an extension of the emissions warranty. 

Table 2 converts the warranty levels shown 

in Table 1 into frequently used emission units. 

Table 1. Mercury 50 Warranty Levels 

Pollutant ppm mg/nm3 

NOx 5 11 

CO 10 13 

UHC 10 8 

Air, fuel and water per ES 9-98 

ppmv at 15% O2, dry basis, steady-state operation 

Table 2. Mercury 50 Emissions in Alternate 

Emissions Units 

Emissions NOx CO UHC 

ppm 5 10 10 

Ib/hr 0.81 0.99 0.57 

tpy 3.6 4.3 2.5 

lb/MMBtu 0.020 0.024 0.014 

lb/MW-hr 

(at gen. terminal) 

0.17 0.21 0.12 

g/bhp-hr 

(turbine shaft power) 

0.06 0.07 0.04 

Emission estimates at 59°F, 60% RH, sea level, 

no losses, full load, LHV 

OTHER POLLUTANT EMISSIONS 

ESTIMATES 

Estimates of non-warranted pollutant emissions 

including particulate matter (PM1 0 ), sulfur dioxide 

(S02 ), and volatile organic compounds (VOC) are 

shown in Table 3. 

Formaldehyde 

An emissions warranty is not available for formaldehyde. In order to estimate ton per year 

emissions of formaldehyde for Maximum 

Achievable Control Technology (MACT) major 

source determination calculations, an emission 

factor of 0.000212 lb/MMBtu can be used. Table 

4 gives the EPA's total HAP and formaldehyde 

emission 

1 
Table 3. PMIO, S02, and VOC Emission Factors 

Pollutant Emission Factor, lb/MMBtu (HHV) Emission Factor Reference 

PM10 0.0419 10/96 AP-42, Table 3.1-1 

S02 0.0034 4/00 AP-42, Table 3.1-2a 

VOC Use 10-20% of UHC value in Table 2 --

Table 4. EPA's Total HAP and Formaldehyde Emission Factors for <50 MW 

Lean-Premix Gas Turbines Burning Natural Gas 

Pollutant Engine Load 

95% Upper Confidence of Data, 

lb/MMBtu (HHV) Memo Reference 

Total HAP > 90% 0.00258 Table 19 

Total HAP All 0.00305 Table 16 

Formaldehyde > 90% 0.00241 Table 19 

Formaldehyde All 0.00288 Table 16 

Source: Revised HAP Emission Factors for Stationary Combustion Turbines, OAR2002-0060, IV-B-09,8/22/03 

factors for <50 MW lean-premix gas turbines 

burning natural gas. 

Table 5 summarizes approximate ton per 

year formaldehyde emissions from the Mercury 

50 based on the 95% Upper Confidence of Data 

emission factors as shown in Table 1 and ISO 

condition fuel flow data. 

Table 5. Formaldehyde Emission Estimates 

for Mercury 50 

Fuel Input, 

MMBtu/hr 

LHV (HHV) 

Formaldehyde Emission 

Estimate, tpy 

Fuel Input, 

MMBtu/hr 

LHV (HHV) All Loads >90% Load 

40.2 (44.3) 0.55 0.46 

Emission estimates at 59°F, 60% RH, sea level, 

no losses, full load 

COLD AMBIENT EMISSIONS ESTIMATES 

Solar's standard temperature range warranty for 

the Mercury 50 is between 0T and 120°F. To 

estimate actual emissions for when the turbine is 

not operating in ULP mode, the following 

expected emission rates were extrapolated from 

San Diego factory tests. Levels may vary at e<-

treme temperatures and as a result of variations 

in other parameters, such as fuel composition 

and fuel quality. Emission warranties cannot be 

offered for ambient temperatures below 0°F. 

Table 6 gives expected emissions (ppm corrected 

to 15% O2) as a function of ambient temperature. 

EMISSIONS ESTIMATES AT <50% LOAD 

The Mercury 50 will remain in low emissions 

mode until the primary zone temperature drops 

below the design allowable primary zone 

Table 6. Expected Mercury 50 Emissions Levels below 0°F 

Ambient Engine Load Fuel NOx, ppm CO, ppm UHC, ppm 

0°Fto-20°F 50 to 100% load Gas 42 100 50 

Below -20°F 50 to 100% load Gas 120 150 75 

2 
temperature. Ambient temperature will be a 

factor. The precise load at which the Mercury 50 

will drop out of low emissions mode is not yet 

defined, but is expected to be below the 50% 

load level. Until further testing is completed, an 

assumption will be made that the ULP combustion system will drop out of low-emission mode 

at loads less than 50%. Table 7 provides 

estimates of NOx, CO, and UHC emissions 

when operating below 50% load. The estimated 

emissions can be assumed to vary linearly as 

load is cecreased from just below 50% load to 

idle. 

Table 7. Estimated Non-ULP Mode Emissions 

NOx, CO, UHC, 

Engine Load ppm ppm PPm 

Less than 50% 120 50 50 

Idle 70 3500 500 

START-UP EMISSIONS 

The start-up duration is the same for cold, warm, 

and hot starts. Estimated start-up emissions are 

summarized in Table 8, in parts per million by 

volume (ppmv), and in Table 9, in pounds per 

start-up. The emission estimates are calculated 

from empirical exhaust characteristics. Sailing 

up the turbine and getting into the ULP mode 

takes three steps: 

1. Purge-crank 

2. Ignition and acceleration to idle 

3. Loading / thermal stabilization 

During the "purge-crank" step, rotation of the 

turbine shaft is accomplished with an electric 

starter motor to remove any residual fuel gas in 

the engine flow path and exhaust. During 

Table 8. Estimated Emissions during Start-up (ppmv) 

Start-up Step 

Combustion 

Mode 

Approx. Time, 

minutes 

NOx, 

ppmv 

CO, 

ppmv 

UHC, 

ppmv 

1. Purge-Crank None 1 - - -

2. Ignition-Idle-Generator Synchronization Diffusion 14 70 3500 500 

3. Loading / Thermal Stabilization Transitional 5 120 1500 250 

4.50% to Full Load ULP Variable <5 <10 <10 

Table 9. Estimated Mercury 50 Emissions per Start-up Sequence and Shutdown Sequence 

Mercury SO 6400 ULP 

Exhaust Flow 

Rate, Ib/hr 02% HzO% NOx, lb CO, lb UHC, lb 

Start-up Step2(14min) 85,178 17.7 2.9 0.70 29.94 2.44 

Step 3 (5 min) 85,178 17.7 2.9 0.60 4.58 0.44 

Total Start-up Emissions, lb ~ ~ - 1.3 34.5 2.9 

Shutdown Step 4 (4.5 min) 144,000 15.8 4.56 0.06 0.07 0.04 

Step 3 (4.5 min) 85,178 17.93 2.69 0.54 4.12 0.39 

Total Shutdown Emissions, lb -- ~ - 0.6 4.2 0.4 

Assumes ISO conditions: 59°F, 60% RH, sea level, no losses. 

Exhaust flow rates for Step 2 and 3 from Development Test Cell data, engine at idle. 

Exhaust flow rates for Step 4 and Mercury 50 Gen 3 Cycle Deck @ 100% load. 

Assumes unit is operating at full load prior to shutdown. 

Assumes gas fuel. 

3 
"ignition and acceleration to idle," fuel is 

introduced into the combustor and ignited in a 

diffusion flame mode and the engine rotor is 

accelerated to idle speed. The third step, "Loading thermal stabilization," consists of applying up 

to 50% load while allowing the combustion flame 

to transition and stabilize. Once 50% load is 

achieved, the turbine transitions to ULP mode 

(Step 4) and the engine control system begins to 

hold the combustion primary zone temperature 

and limit pilot fuel to control the carbon monoxide 

(CO) and nitrogen oxide (NOx) emission levels. 

It is important to note that Steps 2 and 3 are 

short-term transient conditions, with an expected 

duration of less than 20 minutes. No emission 

guarantee is provided by Solar for <50% load. 

SHUTDOWN EMISSIONS 

Normal, planned cool down / shutdown duration 

for the Mercury 50 takes about 9 minutes. 

Typically, the emissions will be similar to the 

start-up sequence's Step 4 for 4.5 minutes and 

Step 3 for the balance of the estimated cool 

down/shutdown duration (assumes unit operating 

at full load). 

COMMISSIONING EMISSIONS 

Commissioning generally takes place over a twoweek period. Static testing, where no combustion 

occurs, usually requires one week and no 

emissions are expected. Dynamic testing, where 

combustion will occur, will see the engine start 

and shut down a number of times during which a 

variety of loads will be placed on the system. It is 

impossible to predict how long the turbine will run 

and in what combustion / emissions mode it will 

be running during this period. The dynamic 

testing period is generally followed by one to two 

days of "tune-up" during which the turbine is 

running at various loads, most likely within lowemissions mode (warranted emissions range). 

4 
Solar Turbines 

A cmipilitr CMtpnr 

Solar Turbines Incorporated 

P.O. Box 85376 

San Diego, CA 92186-5376