Air Emissions - Distributed Generators and Emergency Engines
An Environmental Permitting Fact Sheet
On November 1, 2004, the Department of Energy and Environmental Protection completed a rulemaking effort that adopted a new regulation, Section 22a-174-42 of the Regulations of Connecticut State Agencies (RCSA), and amended three regulations, RCSA Sections 22a-174-3b(e)(2), 22a-174-3a(a)(2)(B) and 22a-174-22(a)(4). The new regulation and amendments address the potential air quality impacts of smaller-scale electric generating units distributed throughout an electrical system, referred to as "distributed generators," and revise the existing requirements for emergency engines consistent with the new distributed generator requirements. The new regulation and amendments became effective January 1, 2005. Subsequently, the Department revoked the general permits under which some distributed generators and emergency engines are operated. Together, these new regulatory requirements and general permit revocations result in changes to the Department's permitting options for distributed generators and emergency engines.
This fact sheet informs distributed generator and emergency engine owners and operators of the regulatory and permit changes so that such owners and operators may address any air permitting or fuel changes necessary for operation in compliance with the new regulatory requirements and permitting options.
Sections 22a-170 and 22a-174 of the Connecticut General Statutes(CGS)
Federal Clean Air Act (42 U.S.C., Sec. 7401 et. seq.)
Sections 22a-174-2a, 22a-174-3a, 22a-174-3b, 22a-174-3c and 22a-174-22 of the Regulations of Connecticut State Agencies (RCSA)
New Regulatory Provisions
The new regulatory provisions include four components, as follows:
New RCSA Section 22a-174-42 (Section 42) establishes a standardized exemption from the duty to obtain an individual permit pursuant to RCSA Section 22a-174-3a (Section 3a) for the owners and operators of distributed generators that are able to operate in compliance with Section 42. By limiting a generator's actual emissions to less than 15 tons per year, the requirements of Section 42 ensure that the generator's impacts are not significant enough to merit the detailed individual permit review process of Section 3a. Section 42 includes output-based standards for emissions of nitrogen oxides (NOx), particulate matter, carbon monoxide and carbon dioxide as well as fuel sulfur content requirements to control emissions of sulfur dioxide.
Revisions to RCSA Section 22a-174-3b (Section 3b) reduce the operating hours and fuel sulfur content requirements for emergency engines.
Revisions to Section 3a provide limited exemptions from the applicability requirements of that section for owners and operators of sources that are operated in compliance with Section 42.
- Revisions to the definition of "emergency" in RCSA Section 22a-174-22 (Section 22) address the operation of an emergency generator when the Independent System Operator for New England (ISO-NE) has declared a capacity deficiency of the New England electric system. Section 42 incorporates this same definition of "emergency."
Revocation of General Permits
Effective February 15, 2005, the Department revoked the General Permit to Construct and/or Operate a New or Existing Emergency Engine. The revocation of the General Permit to Construct and/or Operate a New or Existing Phase I Distributed Generation Engine is effective July 1, 2005.
New Permitting Options and Requirements
The permitting options currently available to the owners and operators of distributed generators and emergency engines and associated operating requirements are highlighted below.
Owners and operators of distributed generators with potential emissions equal to or greater than 15 tons per year have two compliance options:
Operation under Section 42; or
- Applying for and obtaining an individual permit under Section 3a.
Owners and operators of emergency engines with potential emissions equal to or greater than 15 tons per year have three compliance options:
Operation under Section 3b;
Operation under Section 3c; or
- Applying for and obtaining an individual permit under Section 3a.
Fuel Requirements: The owners and operators of distributed generators operating under Section 42 and emergency engines operating under Section 3b must use fuel with a sulfur content that does not exceed that of federal motor vehicle diesel fuel. The current federal limits of 0.05% by weight (500 ppm) will generally be limited to 0.0015% by weight (15 ppm) in retail markets as of September 1, 2006.
Hours of Operation: The owner or operator of a distributed generator operating under Section 42 is limited to the hours of operation determined by a formula in RCSA Section 22a-174-42(b). The owner or operator of an emergency engine operating under Section 3b will be limited to 300 hours in any twelve consecutive months.
NOx RACT: The owner or operator of a distributed generator operating under Section 42 must comply with the emissions testing and emission limit requirements of Section 22, if the generator's potential emissions exceed the daily ozone season threshold. If the requirements of Section 42 limit actual emissions to less than the daily ozone season threshold in Section 22, then the owner or operator is only subject to the compliance plan, record keeping and reporting requirements of Section 22.
For the owners and operators of most emergency engines, Section 42 and the associated amendments will not change the exemption from all except the compliance plan, record keeping and reporting requirements of Section 22. Generators originally classified as distributed generators, that were re-classified as emergency engines after January 1, 2005, are likely to be subject only to the compliance plan, record keeping and reporting requirements of Section 22, unless the generator is operated for testing or maintenance on days that ozone levels are forecast as unhealthy for sensitive groups or higher. Owners and operators of emergency engines should determine their exemption status by reviewing RCSA Section 22a-174-22(b)(5) for the specific requirements applicable to emergency engines.
Bureau of Air Management
Department of Energy and Environmental Protection
79 Elm Street
Hartford, CT 06106-5127
This overview is designed to answer general questions and provide basic information. You should refer to the appropriate statutes and regulations for the specific regulatory language of the different permit programs. This document should not be relied upon to determine whether or not an environmental permit is required. It is your responsibility to obtain and comply with all required permits.
Fact Sheet DEP-AIR-FS-201
Content Last Updated May 2013