NOTE: 1996-04-09 Interim Directive ID 96-2 identified the following changes to Informational Letter IL 88-5:
"Amended by striking out the following references, under Application Procedures:
- section 15.050 of the Oil and Gas Regulations
- Production Facility Application form, parts 1 and 2 and ERCB Guide G-35, and
- section 3 of the Pipeline Regulation"
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Information Letter IL 88-5
9 May 1988
To: All Oil, Gas, and Pipeline Operators
APPLICATION FOR APPROVAL OF NATURAL-GAS-DRIVEN COMPRESSORS
This informational letter supersedes Informational Letter IL 80-30 issued on 22 December 1980 and subsequently amended on 21 November 1984.
Alberta Environment and the ERCB, with assistance from the Alberta Petroleum Industry-Government Environmental Committee, have completed a review of Alberta's oxides of nitrogen (NOx) emission requirement for compression facilities. As a result of this review, a number of changes were made to the design requirements for compressor stations and to the application procedures for obtaining approval to construct and operate these facilities. This informational letter describes
(1) the revised application procedures for approval of compression facilities including application requirements and changes to the method of designing engine exhaust stacks, and
(2) the requirements for the use of low NOx emission engines.
There were several reasons for initiating the review:
- To establish an application procedure that is easier to understand and administer than the previous ones.
- To update the exhaust stack design method including use of a new, recently developed dispersion model which better reflects the results of field studies involving actual measurements. The result is stack design parameters that are less conservative and more valid than those applicable using the older design model.
- To focus on the objective of minimizing overall provincial NOx emissions over the longer term by control at the source.
- To recognize NOx control practices for compression facilities in other jurisdictions and NOx control practices in other industries such as transportation and power generation.
1 APPLICATION PROCEDURES
Unless exempt from the requirement to obtain a Clean Air Permit and Licence as discussed in Sections 1.3.1 and 3 of this letter, an application under the Clean Air Act must be filed for each new or expanding compression facility. Such applications are submitted along with the ERCB application and must include exhaust stack height calculations using the SEEC1 dispersion model and the information noted in Section 1.2 of this letter.
1 Copies of the SEEC model and related documentation are available through the Standards and Approvals Division of Alberta Environment.
For administrative purposes, applications for compressors are divided into three categories; gas plant compressors, field compressor stations and battery compressors, and transmission system compressors. Each type of application is processed by a different Board department.
1.1 Compressor Application Requirements
(a) Gas Plant Compressors
A gas plant compressor is part of a gas processing plant as defined in section 1(1)(q.1) of the Oil and Gas Conservation Act and requires approval under section 26 of the Oil and Gas Conservation Act.
Applications for approval of gas plant compressors, either at a new gas processing plant or for additional compression facilities at an existing gas processing plant, are to be submitted to the ERCB's Gas Department and must address the requirements of section 15.050 of the Oil and Gas Conservation Regulations. When appropriate, a copy of the application will be forwarded by the ERCB to Alberta Environment for review and approval under the Clean Air Act.
(b) Field Compressor Stations and Battery Compressors
Field compressor stations and battery compressors are used for the purpose of delivering gas from one or more wells to a gas plant, to a pipeline, or for a downhole injection. Field compressor stations as defined in section 1.020(2)4.1 of the Oil and Gas Conservation Regulations, and battery compressors which are included in the definition of a battery given in section 1(1)(b) of the Oil and Gas Conservation Act, require approval under section 7.001 of the Oil and Gas Conservation Regulations.
Applications for approval of field compressor stations and battery compressors are to be submitted to the ERCB's Drilling and Production Department using the "Production Facility Application" form, parts 1 and 2, as outlined in the ERCB Guide G-352. When appropriate, a copy of the application will be forwarded by the ERCB to Alberta Environment for review and approval under the Clean Air Act. Guide G-35^2 explains the requirements for completing the application forms and the information to be included with an application. The forms and the guide are available from the ERCB's Maps and Publications Counter located on the ground floor of the Energy Resources Building.
2 ERCB Guide G-35. Guide for Completing a Production Facility Application. March 1988.
(c) Transmission System Compressors
This group includes all compressors that are downstream of gas processing plants and that are located on transmission or utility system pipelines. These compression facilities require approval under Part 4 of the Pipeline Act.
Applications for approval of these compression facilities are to be submitted to the ERCB's Pipeline Department and must address the requirements of section 3 of the Pipeline Regulations. When appropriate, a copy of the application will be forwarded by the ERCB to Alberta Environment for review and approval under the Clean Air Act.
1.2 Clean Air Act Application Requirements
Unless exempt from the requirements to obtain a Clean Air Permit and Licence, applications shall contain the following details for each compression unit in addition to the requirements specified in the Oil and Gas Conservation Regulations and the Pipeline Regulations:
- size of proposed compressor unit in kilowatts (kW),
- exhaust stack height in metres,
- exhaust stack diameter in metres,
- exhaust gas exit temperature in degrees Celsius,
- exhaust gas exit velocity in metres/second,
- NOx emission rate in kilograms per hour (kg/h),
- width, length, and peak height of the compressor building in metres,
- distance from the compressor exhaust stacks to all facility boundary fence lines in metres,
- distance between compressor exhaust stacks in metres (also should be shown on the plot plan), and
- all of the above information for all existing compressor units if the application is for additional compression.
1.3 Calculation of Minimum Exhaust Stack Height
1.3.1 Compression Facilities Exempted from Clean Air Act Permits and Licences
Compression facilities that emit less than 16 kg/h of NOx are exempt from the permit and licence requirements of the Clean Air Act. These facilities include reciprocating engines, gas turbines, and any single- or multiple-unit facility that meets the exemption criteria. Refer to Section 3.1 of this letter to determine eligibility for exemption.
The exhaust stack height for these exempt facilities may be determined by using the lesser of 1.2 times the peak height of the compressor building or the height as determined using the SEEC model. Should the applicant wish to use the SEEC model for determining exhaust stack height, the complete calculations, together with the information listed in Section 1.2 of this letter, must be submitted as part of the application. In no case should the exhaust stack height be less than the building peak height.
1.3.2 All Other New or Expanded Compression Facilities
The requirements of this section apply to both reciprocating engines and gas turbines.
Stack heights for all other new or expanding compression facilities must be sufficient to meet the maximum ground-level concentration (MGLC) of 0.21 parts per million (ppm) of NO2 using the SEEC model and the following:
- Ground-level rather than tree-top concentrations are to be calculated.
- Ground-level concentrations within the boundary (usually the fence) of the facility are to be ignored.
- Any significant NOx emission sources within 0.5 kilometres must be identified by the operator. If the source is licensed under the Clean Air Act, its NOx emission must be included in the stack design calculation for the applied-for compressor. If the source is not licensed under the Clean Air Act, it shall be listed together with any readily available information which would assist Alberta Environment to expeditiously determine whether the unlicensed NOx source would affect the stack design for the applied-for compressor.
- Standby equipment and emergency-only equipment are not included in calculations but must be listed in the application. Standby equipment and emergency-only equipment are defined in Section 3.1 of this letter.
- Emissions from heaters and boilers may be determined from the manufacturer's rating or the United States Environmental Protection Agency rating factors and maximum heat inputs. Such emissions are not included in the calculations if their combined contribution to the total NOx emission is less than 3 per cent. However, they must be listed in the application in any event.
- For reciprocating engines, the lower of either the engine manufacturer's maximum rated power or the rated power at 1000 revolutions per minute (rpm), corrected to site conditions, may be used in calculations. For turbines, the manufacturer's maximum site-rated power should be used.
The exhaust stack height shall be determined using the following method:
(a) Input a proposed stack height and values of the other parameters to the SEEC model as described in Alberta Environment's publication "User's Manual for Alberta Environment Dispersion Models".
(b) If the MGLC of NO2 exceeds 0.21 ppm, increase the proposed stack height by small increments until the MGLC is less than or equal to 0.21 ppm.
(c) In no case may the height of a new or modified stack be less than the building peak height.
1.4 Liquid Waste Handling
Though an application for a Clean Water Act permit and licence will not be required, compressor sites should be designed and constructed in a manner that precludes the continuous discharge of process waste waters and sanitary sewage to the environment within the vicinity of the site. Storage tanks should be used to confine process waste waters, and septic tank and tile-field installations must be used to confine and treat sanitary wastes where necessary. In addition, the engine and compressor lubricants and any chemicals shall be stored in suitable tankage and disposed of in a manner satisfactory to the ERCB and Alberta Environment.
1.5 Noise Guidelines
The ERCB has issued noise guidelines with which any new or expanded facility must comply. If questions arise regarding noise guidelines, applicants should consult with the ERCB's Environment Protection Department.
2 USE OF "LOW NOx" COMPRESSOR DRIVERS
2.1 New or Expanded Facilities
In order to achieve the longer term objective of controlling NOx emissions at the source, effective June 1988, Alberta Environment requires "low NOx" emission technology to be used at all new compression facilities and at all expansions of existing compression facilities when the unit size is greater than 600 kW. Alberta Environment defines "low NOx" as any driver emitting less than 6 grams N0x/kW/h Any technology that is able to achieve this level or lower is acceptable to Alberta Environment. However, using some technologies such as catalytic converters or used engines rebuilt to the low NOx criterion, will require proof that they can meet the low NOx criterion. Such proof might include tests by the United States Environmental Protection Agency or an independent laboratory, general acceptance in other jurisdictions, or in the case of retrofitting used drivers, certification by the applicant or the driver rebuilder that the driver has been rebuilt to meet the low NOx criterion.
In order to allow operators to gain experience with low NOx emission technology, there will be a 12-month phase-in period commencing June 1988 for all new compression facilities or expansion of existing facilities where the unit size is greater than 600 kW but less than 900 kW. In other words, units between 600 kW and 900 kW will not be required to satisfy the low NOx criterion until June 1989; units greater than 900 kW applied for on or after June 1988 must satisfy the low NOx criterion. Should serious operating problems with low NOx drivers be encountered during this phase-in period, the ERCB and Alberta Environment may extend the phase-in period or modify the requirements.
Relocating a used driver in the 600- to 2200-kW size range without retrofitting to meet the low NOx criterion will be permitted only on an individual, show-cause basis. Companies wishing to do so may submit an application to the ERCB's Gas Department, Drilling and Production Department, or Pipeline Department, as appropriate, documenting the impact that retrofitting the used driver to meet the low NOx criterion would have on the economic viability of the overall project. Such documentation should include an economic analysis comparing the two cases and showing the assumptions and input data used. Other reasons or information pertinent to the situation that may aid the Board in reaching its decision should also be included. However, the principal consideration will be the impact on the project viability. The Board will review the application and the reasonableness of the economic analysis having regard for the internal economic criteria that it uses, then render its decision.
In order to retain flexibility in handling such applications and because the criteria may change over time to reflect changing circumstances, the Board does not believe it appropriate to publish its internal economic criteria here. However, these criteria are consistent with other areas such as gas conservation.
Replacement of an old unit with another used unit of the same size with no increase in NOx emissions is exempt from the low NOx requirement.
2.2 Existing Facilities
The term "grandfathering" means to exempt from a new policy those existing facilities which would otherwise contravene the policy. For purposes of this letter, all facilities which have not increased NOx emissions since December 1980 and which have a calculated MGLC of NO2 greater than 0.21 ppm as determined by the SEEC model, will be grandfathered except those currently under review by Alberta Environment. Facilities will retain the grandfathered status as long as there is no increase in the total NOx emissions nor in the calculated MGLC of NO2. Facilities which have increased NOx emissions since December 1980 either already meet the calculated MGLC of NO2 or have already been contacted by Alberta Environment as part of the special review.
3 CRITERIA FOR EXEMPTION FROM CLEAN AIR PERMIT AND LICENCE REQUIREMENTS
3.1 Permanent Facilities
A compression facility, whether it be an existing, expanded, modified, or new facility, is exempt from sections 3, 4, and 5 of the Clean Air Act if its total NOx emissions are equal to or less than 16 kg/h.
To determine if a compression facility is exempt from licensing under the Clean Air Act, estimate the total NOx emission (NO + NO2) using one of the following:
- manufacturer's NOx emission factors, or
- United States Environmental Protection Agency NOx emission factors ("Compilation of Air Pollutant Emission Factors, Publication AP-42 (1981)").
For reciprocating engines, the lower of either the manufacturer's maximum engine power rating or the power rating at 1000 rpm, corrected for site elevation, may be used to determine total NOx emission. For turbines, the manufacturer's maximum site-rated power should be used. Corrections for site elevation must be documented in the application.
Intermittent NOx emissions from standby equipment or equipment used only for emergency purposes may be omitted from the NOx calculation. Note that the standby or emergency equipment does not include equipment idle as a result of over-design or temporary reductions in throughput but refers to equipment used only as a temporary substitute for a normally operating unit. NOx emissions from flare stacks and pits may also be excluded.
Any subsequent expansion or modification to a compression facility that results in the total NOx emissions exceeding 16 kg/h will render the facility subject to the approval requirements of the Clean Air Act.
3.2 Temporary Facilities
All temporary facilities are exempt from sections 3, 4, and 5 of the Clean Air Act. Temporary facilities are those in existence for not more than 1 year. Extension of the use of temporary facilities beyond 1 year will render them subject to the requirements of permanent facilities.
Further inquiries concerning this letter may be directed to the Gas Processing Section of the ERCB's Gas Department at 297-8408 or 297-8531, the Production Section of the ERCB's Drilling and Production Department at 297-8321, or the Air Quality Section of Alberta Environment at 427-5872.
[signed by]
ENERGY RESOURCES CONSERVATION BOARD
- N. A. Strom, P.Eng.
- Vice Chairman
-
- and
ALBERTA ENVIRONMENT
- V. A. MacNichol, P.Eng.
- Deputy Minister
