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B.C. Air Quality

Emission Criteria for Gas Turbines (December 1992)

Foreword

The Emission Criteria for Gas Turbines were developed based on the Ministry of Environment's Best Available Control Technology (BACT) policy, and in consultation with British Columbia stakeholders. These criteria update and elaborate on the criteria set for natural gas combustion in the Pollution Control Objectives for Food Processing, Agriculturally Oriented and Other Miscellaneous Industries of British Columbia, published in 1975.

Ministry of Environment policy states that regional Environmental Protection Managers must use BACT criteria as a starting point when establishing minimum permit limits for new or modified facilities.

1. Definitions

"Major modification" means any physical change in an existing plant or change in the method of operation which results or may result in either an emission rate of any air pollutant greater than that specified by the permit, or the emission of any air pollutant which is subject to provincial control and was not previously emitted. The following should not be regarded as major modification:

  1. routine maintenance or repair; and
  2. increased production rate or increased hours of operation which do not exceed the limits of production and hours specified by the permit conditions.

2. Applicability

These emission criteria are effective from the date of issuance and apply immediately to:

  1. all new gas turbines which are permitted after the effective date;
  2. existing gas turbines undergoing major modifications; nd
  3. as appropriate, existing facilities as per the ministry's BACT policy.

The following installations are exempt from the emission criteria:

  1. gas turbines of less than 3 megawatts (MW) shaft power; and
  2. gas turbines used for emergency, standby, or temporary replacement purposes (provided that maximum annual operating hours of the substituted equipment do not exceed 10% of the normal annual operating schedule of the primary equipment).

Installations of multiple units, each less than 3 MW, will be required to meet the emission limits for units larger than 3 MW, if the total capacity of the installation exceeds 3 MW.

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3. Emission Limits

The discharge of contaminants into the atmosphere from a gas turbine should not exceed the limits listed in tables 1 and 2, as applicable.

4. Requirements for Continuous Emission Monitoring

Table 1: Emission Criteria and Monitoring Requirements for Gas Turbines with Capacity greater than 3 3 MW and less than or equal to 25 MW

Contaminant

Fuel

Criteria (a)
(mg/m3)

Averaging
Period

Monitoring
Requirement
Nitrogen Oxides (NOx as NO2) Natural Gas 80 1 hour As specified by the Regional Manager
  Oil 125 1 hour  
Carbon Monoxide Any 80 1 hour As specified by the Regional Manager

(a) Reference conditions of 20 degrees C, 101.325 kPa, and dry gas concentration corrected to flue gas oxygen content of 15% by volume.

Table 2: Emission Criteria and Monitoring Requirements for Gas Turbines with Capacity greater than 25 MW

Contaminant

Fuel

Criteria (a)
(mg/m3)

Averaging
Period

Monitoring
Requirement
Nitrogen Oxides (NOx as NO2) Natural Gas 17 or 48 (b) 1 hour Continuous
  Oil 34 (c) or 80 (b) 1 hour Continuous
Carbon Monoxide Any 58 1 hour Continuous
Ammonia Any 7 (d) 1 hour Continuous

(a) Reference conditions of 20 degrees C, 101.325 kPa, and dry gas concentration corrected to flue gas oxygen content of 15% by volume.

(b) Apply to gas pipeline application and other installations where selective catalytic reduction (SCR) is demonstrated to be inappropriate.

(c) NOx emission level due to fuel nitrogen content assumed to be under 600 ppm.

(d) If ammonia injection is applied.