Turbine emissions calculator: guide to reporting

Use the calculator to help you report emissions from distillate oil-fired stationary gas turbines to the National Pollutant Release Inventory (NPRI).

Reporting to the National Pollutant Release Inventory

If your facility meets the NPRI reporting requirements, you must report the total quantities of NPRI substances released (to air, water or land), disposed of, or transferred for recycling.

Note: This document focuses on releases from distillate oil-fired stationary gas turbines. Keep in mind that you must consider releases from all sources when reporting to the NPRI, not just those that result from the combustion of fuel oil.

For more information about NPRI reporting requirements, refer to the guide for reporting to the NPRI.

General information about oil-fired stationary gas turbines

Stationary gas turbines (also referred to as “combustion turbines”) are used for various applications, including electric power generation, cogeneration, fuel oils transmission and some process applications.

Distillate oils include No.1 and No. 2 fuel oil. The latter is the primary fuel used in gas turbines, other than natural gas.

Published emission factors

While there are many acceptable methods for estimating emissions when you report to the NPRI, the Emissions Calculator uses published emission factors. Published emission factors are those that have been published by government agencies and industry associations for use in their particular application or industry sector. These factors are commonly used and accepted by regulatory agencies for estimating emissions because they are based on emission test data for similar sources and represent average or typical rates with recognized data quality parameters.

The emission factors from the combustion of fuel oils and specifically from distillate oil/diesel-fired turbines, which were published by the United States Environmental Protection Agency (EPA), AP-42, were selected to be included in the Emissions Calculator.

The EPA AP-42 emission factors are presented in Table 1, along with the associated data quality ratings. The EPA AP-42 emission factor ratings are as follows:

• A (excellent) – factor derived from sound test data taken from many randomly selected facilities
• B (above average) – factor derived from sound test data taken from a “reasonable” number of facilities
• C (average) – factor developed from test data collected using unproven or new methods, or lacking background information, from a reasonable number of facilities
• D (below average) – factor developed from test data as above, from a small number of facilities
• E (poor) – Factor developed from test data based on poor or new methodology, and from a small number of facilities that do not represent a random sample of the industry

(*) Using equation 1.01xS (AP-42 chapter 3, Table 3.1-2a) where S = percent sulfur in fuel

Calculate emissions for distillate oil-fired gas turbines

Emissions from distillate oil/diesel-fired turbines are calculated as follows in the Emissions Calculator:

Annual Emissions (kg/year)

= distillate oil usage (m³/year) x EF (lb/MMBtu) x HHV (GJ/m³) x 0.454 (kg/lb) x 0.948 (MMBtu/GJ)

The emission factors are presented in fuel input units of GJ/m³. If not specified by the user, a default average distillate oil/diesel heating value of 38.7 GJ/m³ (or 139 MMBtu/10³ U.S.gal) was used to calculate emissions. This value is cited in AP-42, Table 3.1-1, Note “f”, as the average distillate oil heating value.

For distillate oil/diesel-fired turbines, a single emission factor was listed for filterable particulate matter (PM). As a result, this emission factor (4.3x10^-3 lb/MMBtu), as presented on Table 3.1-2a of U.S. EPA AP-42 Section 3.1, was used to estimate emissions of total particulate matter (TPM), particulate matter less than or equal to 10 micrometers in diameter (PM₁₀) and particulate matter less than or equal to 2.5 micrometers in diameter (PM_2.5).

Emission factors preceded with a “<” in AP-42 Section 3.1 represent values at one-half of the detection limit. These were used in the Emissions Calculator.

Pollution control devices and estimated control efficiencies

If you use an emission control device and the default emission factor is uncontrolled, the emission factor equation may be adjusted to take the control efficiency into account, as follows:

E = A x EF x ((100 – control efficiency)/100)

where:

• E = emissions
• A = activity rate
• EF = emissions factor

The Emissions Calculator lets you incorporate control efficiencies in the input tab. Table 3 lists common pollution control devices and the associated control emission factors for distillate oil-fired turbines to control emissions of NO_x.

For distillate oil-fired turbines, both uncontrolled and controlled (water steam injection) carbon monoxide (CO) and oxides of nitrogen (NO_X) emission factors were listed in Table 3.1-1 of U.S. EPA AP-42 Section 3.1 (4/00).  The controlled emission factors for CO and NO₂ were ratioed to their respective uncontrolled emission factors, and then the efficiency percent values were calculated. There is a drop-down menu in the Emissions Calculator.

Water steam injection is a water or steam injection technology that has been demonstrated to effectively suppress NO_X emissions from gas turbines, however both CO and VOC emissions are increased by water injection, with the level of CO and VOC increases dependent on the amount of water injection. For this reason, the control efficiency for CO is negative, as there is an increase in emissions with water steam injection.  At this time, no information is available to accurately adjust the VOC estimates for the water injection control method.

Sulphur content of fuel oils

You must input the sulphur content of the distillate oil into the Emissions Calculator in order to calculate the sulphur dioxide (SO₂) emissions.

If you know the sulphur content of the fuel, use the site-specific value. In the absence of site-specific data, sulphur content data downloaded from Open Canada were used to establish default values by region.

The ECCC Sulphur in liquid fuels data from 2003 to 2016 were used to develop the averages listed under Table 3. These data include information from several regions. The average value in each region for this 2003-2016 period was carried forward as the default sulphur content for the Emissions Calculator.

Table 3 shows the default sulphur content for three fuel types that were used in the Emissions Calculator.