VIA ELECTRONIC SUBMITTAL 

September 8, 2010 

Air and Radiation Docket and Information Center 

U.S. Environmental Protection Agency 

Mailcode 6102T 

Attention Docket ID Number EPA-HQ-OAR-2010-0295 

1200 Pennsylvania Avenue NW 

Washington, DC 20460 

Re: Comments on EPA’s proposed Standards of Performance for Stationary Compression Ignition and 

Spark Ignition Internal Combustion Engines (Docket ID Number EPA- HQ-OAR-2010-0295) 

Dear Docket Clerk: 

Trinity Consultants, Inc. (“Trinity”) is pleased to provide the following comments on the Environmental 

Protection Agency’s (“EPA’s” or the “Agency’s”) proposed revisions to the New Source Performance 

Standards (“NSPS”) for Stationary Compression Ignition Internal Combustion Engines, which was 

published in the Federal Register on June 8, 2010.1

 As an environmental consulting firm specializing in 

air quality issues, Trinity has an interest in the development of this and other NSPS, as well as in how 

EPA interprets the applicability of these standards. In this regard, we submit the following specific 

comments: 

1. Treating all temporary replacement engines as stationary engines is a reversal of EPA’s 

historical regulation of nonroad engines. 

Trinity is primarily concerned with EPA’s preamble discussion of the regulatory status of temporary 

replacement engines, not with EPA’s proposed emission standards or regulatory text. Specifically, 

Trinity is concerned that EPA’s statements regarding the status of portable engines that temporarily 

replace stationary engines will, at best, cause confusion on the part of regulators and the regulated 

community alike; at worst, EPA’s statements could result in a de facto prohibition on the use of 

temporary portable engines in some jurisdictions. Trinity thus urges EPA to clarify its statement and 

explain that the same position it adopted in 2006, when the Agency promulgated NSPS Subpart IIII, 

remains in effect. 

In particular, Trinity is troubled by the first several sentences of the following passage: 

Portable engines that replace existing stationary engines on a temporary basis are 

considered stationary engines. This provision allows the permitting authority to count 

the emissions of the temporary unit in the emission from the stationary source, as it 

would for the permanent unit. This prevents sources from avoiding the counting of such 

units in its projected or actual emissions. EPA agrees with comments that with regard to 

 

1

 75 Fed. Reg. 32,612. 

12770 Merit Drive, Suite 900, Dallas, TX 75251 U.S.A.  (800) 229-6655  Fax (972) 385-9203

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Docket ID No. EPA-HQ-OAR-2010-0295 Page 2 of 5 

September 8, 2010 

temporary replacement engines, which are generally portable and moved from place to 

place, it is most appropriate that these engines, though considered stationary, should be 

allowed under the NSPS to meet requirements for mobile nonroad engines. These 

sources are not under the long-term control (or in many cases the short-term control) of 

the local source, and, therefore it is appropriate to hold them to the requirements for 

similar sources that are mobile in character. EPA also notes that under the pre-existing 

general provisions for 40 CFR Part 60, the fact that an engine moves from place to place 

does not, by the sole basis of that movement, make the engine a “new” engine for the 

purposes of the NSPS. 

75 Fed. Reg. at 32,616 (emphasis added). 

While Trinity agrees with most of this passage, particularly the policy of allowing portable engines to 

meet nonroad engine emission standards, it does not agree with the statement that portable engines that 

replace existing stationary engines on a temporary basis are considered stationary engines. This 

represents a reversal of EPA’s historical treatment of portable engines and would lead to results contrary 

to the Agency’s likely intentions. 

EPA has traditionally distinguished between nonroad and stationary internal combustion engines on the 

basis of engine mobility and residence time, and it has generally treated portable engines that remain in a 

particular location for less than 12 months as nonroad engines. See 59 Fed. Reg. 31,306, 31,311 (June 17, 

1994). EPA has made clear that sources cannot game the system by constantly relying on portable 

engines to avoid regulation (e.g., federal New Source Review and/or Title V operating permit program), 

and hence has made clear that “if an engine is replaced by another engine within the 12 month period, the 

replacement engine should be considered in calculating the consecutive time period.” Id. But this has not 

been applied in the context of when a portable engine replaces a permanent stationary engine on a 

temporary basis, such as for maintenance, repair, or unexpected failures that cause the engines to be 

offline for a temporary period. Indeed, in addressing this very issue in 2006 when promulgating Subpart 

IIII, EPA stated: 

EPA agrees that the engines themselves that are used for temporary replacement of 

stationary engines are nonroad engines and are not covered by stationary engine 

regulations, as long as they meet the definition of nonroad engine and if they are not used 

beyond the residence limitations in paragraph 2(iii) on the nonroad engine definition in 

40 CFR 1068.30. 

 

Response to Comments on Proposed Standards of Performance for Stationary Compression Ignition 

Internal Combustion Engines, EPA Docket EPA-HQ-OAR-2005-0029 at 166 (emphasis added). 

EPA’s current statement is an unequivocal reversal of its longstanding position, at least as applied in the 

context of subpart IIII. 

Trinity is concerned that by treating portable engines that temporarily replace stationary engines as 

stationary sources, EPA could effectively prohibit their very intended use as a temporary replacement. 

The value to a source of a portable engine is its ability to be moved quickly to a site to replace a stationary 

engine that has unexpectedly malfunctioned or is in need of repair. These events are infrequent, but when 

they happen, time is of the essence. An entire facility’s operations can be at stake. These events also tend 

to be short-lived; once the maintenance, repair or permanent replacement is made, the stationary engine is 

returned to service and the portable engine is removed from that location. A number of state and local 

agencies acknowledge this type of use and have a categorical pre-construction permitting exemption for 
Docket ID No. EPA-HQ-OAR-2010-0295 Page 3 of 5 

September 8, 2010 

nonroad or portable engines, as long as the engine meets the definition of nonroad engine under 40 CFR 

1068.30 (excluding paragraph (2)(ii) of that definition) (e.g., Massachusetts). If temporary replacement 

generators were considered stationary sources and subject to NSPS IIII, albeit with limited requirements, 

a number of state and local agencies would potentially require pre-construction approval based on the fact 

that the engines are subject to an NSPS standard (e.g., Colorado and Oklahoma). Moreover, if portable, 

temporary replacement engines are regulated as stationary sources, it might not be possible for such 

engines to be placed into service without first obtaining a state construction permit, a process that can take 

several months. Obviously, this would be of little value to sources in need of temporary, emergency 

replacement. 

Moreover, in states and local jurisdictions that require permitting and ambient air quality demonstration 

for all “stationary sources,” it might not even be possible to permit larger portable, temporary replacement 

engines in light of the national ambient air quality standard (“NAAQS”) for nitrogen oxide (“NOx”). 

Meeting the 1-hour NOx NAAQS for large engines often requires substantial stack heights for air 

dispersion purposes. Thus, the regulation of portable, temporary replacement engines as stationary 

sources would mean that portable engines would have to be equipped with or have the ability to be tied 

into the existing stacks before they could be permitted and used. Again, this could result in an effective 

ban on portable temporary replacement engines at many sources. This is not in the best interest of any 

stakeholder. 

EPA does not need to treat portable engines that replace stationary engines on a temporary basis as 

stationary engines to meet its policy goal of ensuring that sources cannot circumvent their permitting 

obligations through the intentional substitution of portable replacement engines. EPA’s existing 

definition of nonroad engine already prohibits this type of behavior. See 59 Fed. Reg. at 31,311. Thus, a 

facility cannot avoid triggering underlying permitting thresholds (e.g., 100 tons per year for Title V 

purposes) by intentionally shutting down its stationary engine and instead running a portable replacement 

engine. Instead of treating all portable replacements as stationary engines, EPA, at the very least, should 

clarify that portable engines that temporarily replace stationary engines that are undergoing verifiable 

repair or maintenance are not considered stationary engines. Facilities that could not verify the 

“legitimacy” of the temporary replacement would have to consider their portable engines as stationary 

sources for emission calculation purposes. This approach would at least recognize the purpose and need 

for temporary engines. 

2. Emergency engines should be allowed to participate in demand response programs for 60 hours 

per year as part of normal emergency use. 

Trinity is concerned that limiting emergency engine operation to 15 hours per year as part of an 

emergency demand response program is too restrictive to ensure the reliability of the nation’s electrical 

grid. We believe that emergency demand response programs are initiated infrequently and only when 

necessary to avoid brownouts and blackouts. Thus, EPA should not arbitrarily limit the hours an 

emergency generator can participate in such programs. Alternatively, the limit should be raised from 15 

to 60 hours. 

Emergency demand response programs have been developed by many companies that manage the electric 

grid throughout the United States. These emergency demand response programs are rarely initiated, but 

when they are, they are done so by the transmission system operators to prevent brownouts and blackouts 

due to insufficient supply of power to the grid. Owners and operators of emergency generators 

participating in emergency demand response programs do not supply power to the grid; all power is used 

at the individual facility. By utilizing selected owners and operators of emergency engines in the 

emergency demand response program, transmission system operators are able to prevent rolling 
Docket ID No. EPA-HQ-OAR-2010-0295 Page 4 of 5 

September 8, 2010 

brownouts and blackouts from occurring. Without emergency demand response programs, there will be a 

greater frequency of rolling blackouts in which case all emergency engines within the region would be 

engaged because of a loss of power, versus a select subset of emergency generators being called by the 

Independent System Operators to maintain the integrity of the grid. EPA acknowledges the need for 

emergency demand response programs in the proposed revisions to the Standards of Performance for 

Stationary Compression Ignition and Spark Ignition Internal Combustion Engines:

You may operate your emergency stationary ICE up to 50 hours per year in non-emergency 

situations, but those 50 hours are counted towards the 100 hours per year provided for 

maintenance and testing. The 50 hours per year for non-emergency situations cannot be used for 

peak shaving or to generate income for a facility to supply power to an electric grid or otherwise 

supply power as part of a financial arrangement with another entity; except that owners and 

operators may operate the emergency engine for a maximum of 15 hours per year as part of a 

demand response program if the regional transmission organization or equivalent balancing 

authority and transmission operator has determined there are emergency conditions that could 

lead to a potential electrical blackout, such as unusually low frequency, equipment overload, 

capacity or energy deficiency, or unacceptable voltage level. The engine may not be operated for 

more than 30 minutes prior to the time when the emergency condition is expected to occur, and 

the engine operation must be terminated immediately after the facility is notified that the 

emergency condition is no longer imminent. The 15 hours per year of demand response 

operation are counted as part of the 50 hours of operation per year provided for nonemergency 

situations. The supply of emergency power to another entity or entities pursuant to financial 

arrangement is not limited by this paragraph (d)(4), as long as the power provided by the financial 

arrangement is limited to emergency power. 

Proposed 40 CFR 60.4211(f)(4) and proposed 40 CFR 60.4243(d)(4) (emphasis added) 

Emergency demand response programs are only instituted in cases of true emergencies, and recent history 

suggests that the emergency generators will be rarely called to participate in emergency demand response 

programs. Thus, Trinity recommends that the hour restrictions be eliminated or alternatively that draft 

rule 40 CFR 60.4243(d)(4) be updated to read “...owners and operators may operate the emergency 

engine for a maximum of 60 hours per year or the amount of time required by the Independent System 

Operator tariff, whichever is less, as part of a demand response program...” It is also recommended that 

the EPA eliminate the requirement that the hours operated in emergency demand response programs be 

counted towards to 50 hours of operation per year in nonemergency situations. 

One significant benefit to participants in these programs is the ability to control the transition from power 

being provided by the utility to power being provided by the emergency generators on site. When the 

power from the local utility is interrupted, automatic switchgear systems at a facility automatically 

transition the building load to emergency generators. However, in this uncontrolled situation, there is 

typically a momentary loss in power to the facility and to the services the facility provides. This loss can 

result in interruptions of critical services. By participating in emergency demand response programs, 

owners and operators are able to control and monitor the transition of the building load, ensuring the 

continued, seamless quality of service. 

Trinity recognizes that the proper long term solution to address the burden on our nation’s energy grid is 

the addition of base load power generation to the system. A newly installed natural-gas fired turbine has 

much lower emissions per MW of power generated than diesel-fired engines. However, it will take years 

for the utilities to add the needed generating capacity to the grid, due to the extended amount of time 

required to site the stations, obtain the necessary construction and environmental approvals, and build the 

stations. As the peak energy demand continues to increase, emergency demand response programs are 
Docket ID No. EPA-HQ-OAR-2010-0295 Page 5 of 5 

September 8, 2010 

necessary to bridge the gap between our country’s current energy needs versus the available supply of 

power. 

* * * 

For the reasons set forth in this letter, Trinity requests that EPA clarify that portable engines that replace 

existing stationary engines on a temporary basis are not themselves stationary sources under the Clean Air 

Act, and that owners and operators can operate in emergency demand response programs for up to 60 

hours per year. 

Trinity appreciates this opportunity to provide comments on this proposed rule and hopes that these 

comments will be integrated into the final rule in a manner that will make it more flexible, less 

burdensome, and promote good environmental and energy policy. At your request, we would be happy to 

provide additional information. I can be reached at (253) 867-5600 or jmitchel@trinityconsultants.com. 

Sincerely, 

TRINITY CONSULTANTS 

Jack Mitchell 

Senior Consultant