# Commission Implementing Decision (EU) 2017/1442 of 31 July 2017 establishing best available techniques (BAT) conclusions, under Directive 2010/75/EU of the European Parliament and of the Council, for large combustion plants (notified under document C(2017) 5225) (Text with EEA relevance), Division BAT 44: In order to prevent or reduce CO emissions to air from the combustion of natural gas, BAT is to ensure optimised combustion and/or to use oxidation catalysts.

Extent: E+W+S+N.I.

Table 24
BAT-associated emission levels (BAT-AELs) for NOX emissions to air from the combustion of natural gas in gas turbines
These BAT-AELs also apply to the combustion of natural gas in dual-fuel-fired turbines.
In the case of a gas turbine equipped with DLN, these BAT-AELs apply only when the DLN operation is effective.
These BAT-AELs do not apply to existing plants operated < 1 500 h/yr.
Optimising the functioning of an existing technique to reduce NOX emissions further may lead to levels of CO emissions at the higher end of the indicative range for CO emissions given after this table.
These BAT-AELs do not apply to existing turbines for mechanical drive applications or to plants operated < 500 h/yr.
For plants with a net electrical efficiency (EE) greater than 39 %, a correction factor may be applied to the higher end of the range, corresponding to [higher end] × EE/39, where EE is the net electrical energy efficiency or net mechanical energy efficiency of the plant determined at ISO baseload conditions.
The higher end of the range is 80 mg/Nm3 in the case of plants which were put into operation no later than 27 November 2003 and are operated between 500 h/yr and 1 500 h/yr.
For plants with a net electrical efficiency (EE) greater than 55 %, a correction factor may be applied to the higher end of the BAT-AEL range, corresponding to [higher end] × EE/55, where EE is the net electrical efficiency of the plant determined at ISO baseload conditions.
For existing plants put into operation no later than 7 January 2014, the higher end of the BAT-AEL range is 65 mg/Nm3.
For existing plants put into operation no later than 7 January 2014, the higher end of the BAT-AEL range is 55 mg/Nm3.
For existing plants put into operation no later than 7 January 2014, the higher end of the BAT-AEL range is 80 mg/Nm3.
The lower end of the BAT-AEL range for NOX can be achieved with DLN burners.
These levels are indicative.
For existing plants put into operation no later than 7 January 2014, the higher end of the BAT-AEL range is 60 mg/Nm3.
For existing plants put into operation no later than 7 January 2014, the higher end of the BAT-AEL range is 65 mg/Nm3.
Type of combustion plant
Combustion plant total rated thermal input(MWth)
BAT-AELs (mg/Nm3)
Yearly average
Daily average or average over the sampling period
Open-cycle gas turbines (OCGTs)
New OCGT
≥ 50
15–35
25–50
Existing OCGT (excluding turbines for mechanical drive applications) — All but plants operated < 500 h/yr
≥ 50
15–50
25–55
Combined-cycle gas turbines (CCGTs)
New CCGT
≥ 50
10–30
15–40
Existing CCGT with a net total fuel utilisation of < 75 %
≥ 600
10–40
18–50
Existing CCGT with a net total fuel utilisation of ≥ 75 %
≥ 600
10–50
18–55
Existing CCGT with a net total fuel utilisation of < 75 %
50–600
10–45
35–55
Existing CCGT with a net total fuel utilisation of ≥ 75 %
50–600
25–50
35–55
Open- and combined-cycle gas turbines
Gas turbine put into operation no later than 27 November 2003, or existing gas turbine for emergency use and operated < 500 h/yr
≥ 50
No BAT-AEL
60–140
Existing gas turbine for mechanical drive applications — All but plants operated < 500 h/yr
≥ 50
15–50
25–55
As an indication, the yearly average CO emission levels for each type of existing combustion plant operated ≥ 1 500 h/yr and for each type of new combustion plant will generally be as follows:
New OCGT of ≥ 50 MWth: < 5–40 mg/Nm3. For plants with a net electrical efficiency (EE) greater than 39 %, a correction factor may be applied to the higher end of this range, corresponding to [higher end] × EE/39, where EE is the net electrical energy efficiency or net mechanical energy efficiency of the plant determined at ISO baseload conditions.
Existing OCGT of ≥ 50 MWth (excluding turbines for mechanical drive applications): < 5–40 mg/Nm3. The higher end of this range will generally be 80 mg/Nm3 in the case of existing plants that cannot be fitted with dry techniques for NOX reduction, or 50 mg/Nm3 for plants that operate at low load.
New CCGT of ≥ 50 MWth: < 5–30 mg/Nm3. For plants with a net electrical efficiency (EE) greater than 55 %, a correction factor may be applied to the higher end of the range, corresponding to [higher end] × EE/55, where EE is the net electrical energy efficiency of the plant determined at ISO baseload conditions.
Existing CCGT of ≥ 50 MWth: < 5–30 mg/Nm3. The higher end of this range will generally be 50 mg/Nm3 for plants that operate at low load.
Existing gas turbines of ≥ 50 MWth for mechanical drive applications: < 5–40 mg/Nm3. The higher end of the range will generally be 50 mg/Nm3 when plants operate at low load.
In the case of a gas turbine equipped with DLN burners, these indicative levels correspond to when the DLN operation is effective.
Table 25
BAT-associated emission levels (BAT-AELs) for NOX emissions to air from the combustion of natural gas in boilers and engines
Optimising the functioning of an existing technique to reduce NOX emissions further may lead to levels of CO emissions at the higher end of the indicative range for CO emissions given after this table.
These BAT-AELs do not apply to plants operated < 1 500 h/yr.
For plants operated < 500 h/yr, these levels are indicative.
These BAT-AELs only apply to spark-ignited and dual-fuel engines. They do not apply to gas-diesel engines.
In the case of engines for emergency use operated < 500 h/yr that could not apply the lean-burn concept or use SCR, the higher end of the indicative range is 175 mg/Nm3.
Type of combustion plant
BAT-AELs (mg/Nm3)
Yearly average
Daily average or average over the sampling period
New plant
Existing plant
New plant
Existing plant
Boiler
10–60
50–100
30–85
85–110
Engine
20–75
20–100
55–85
55–110
As an indication, the yearly average CO emission levels will generally be:
< 5–40 mg/Nm3 for existing boilers operated ≥ 1 500 h/yr,
< 5–15 mg/Nm3 for new boilers,
30–100 mg/Nm3 for existing engines operated ≥ 1 500 h/yr and for new engines.

---
Source: https://www.legislation.gov.uk/eudn/2017/1442/annex/division/4/division/4.1/division/4.1.2/division/4 (the official version)
Page: https://openlegislation.uk/eu-decision-2017-1442/annex/division-4/division-4.1/division-4.1.2/division-4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.