Division BAT 40 In order to increase the energy efficiency of natural gas combustion, BAT is to use an appropriate combination of the techniques given in BAT 12 and below.

United Kingdom

Technique	Description	Applicability
a.	Combined cycle	See description in Section 8.2	Generally applicable to new gas turbines and engines except when operated < 1 500 h/yr. Applicable to existing gas turbines and engines within the constraints associated with the steam cycle design and the space availability. Not applicable to existing gas turbines and engines operated < 1 500 h/yr. Not applicable to mechanical drive gas turbines operated in discontinuous mode with extended load variations and frequent start-ups and shutdowns. Not applicable to boilers

Technique

Description

Applicability

Combined cycle

See description in Section 8.2

Generally applicable to new gas turbines and engines except when operated < 1 500 h/yr.

Applicable to existing gas turbines and engines within the constraints associated with the steam cycle design and the space availability.

Not applicable to existing gas turbines and engines operated < 1 500 h/yr.

Not applicable to mechanical drive gas turbines operated in discontinuous mode with extended load variations and frequent start-ups and shutdowns.

Not applicable to boilers

Table 23

BAT-associated energy efficiency levels (BAT-AEELs) for the combustion of natural gas

Type of combustion unit	BAT-AEELs^f1 ^f2
These BAT-AEELs do not apply to units operated < 1 500 h/yr.
In the case of CHP units, only one of the two BAT-AEELs ‘Net electrical efficiency’ or ‘Net total fuel utilisation’ applies, depending on the CHP unit design (i.e. either more oriented towards electricity generation or heat generation).
Net total fuel utilisation BAT-AEELs may not be achievable if the potential heat demand is too low.
These BAT-AEELs do not apply to plants generating only electricity.
These BAT-AEELs apply to units used for mechanical drive applications.
These levels may be difficult to achieve in the case of engines tuned in order to reach NO_X levels lower than 190 mg/Nm³.
	Net electrical efficiency (%)		Net total fuel utilisation (%)^f3 ^f4	Net mechanical energy efficiency (%) ^f5
	New unit	Existing unit	Net total fuel utilisation (%)^f3 ^f4	New unit	Existing unit
Gas engine	39,5–44^f6	35–44	56–85	No BAT-AEEL.
Gas-fired boiler	39–42,5	38–40	78–95	No BAT-AEEL.
Open cycle gas turbine, ≥ 50 MWth	36–41,5	33–41,5	No BAT-AEEL	36,5–41	33,5–41
Combined cycle gas turbine (CCGT)
CCGT, 50–600 MW_th	53–58,5	46–54	No BAT-AEEL	No BAT-AEEL
CCGT, ≥ 600 MW_th	57–60,5	50–60	No BAT-AEEL	No BAT-AEEL
CHP CCGT, 50–600 MW_th	53–58,5	46–54	65–95	No BAT-AEEL
CHP CCGT, ≥ 600 MW_th	57–60,5	50–60	65–95	No BAT-AEEL

Annotations

f1: These BAT-AEELs do not apply to units operated < 1 500 h/yr.
f2: In the case of CHP units, only one of the two BAT-AEELs ‘Net electrical efficiency’ or ‘Net total fuel utilisation’ applies, depending on the CHP unit design (i.e. either more oriented towards electricity generation or heat generation).
f3: Net total fuel utilisation BAT-AEELs may not be achievable if the potential heat demand is too low.
f4: These BAT-AEELs do not apply to plants generating only electricity.
f5: These BAT-AEELs apply to units used for mechanical drive applications.
f6: These levels may be difficult to achieve in the case of engines tuned in order to reach NO_X levels lower than 190 mg/Nm³.