Background

The Technische Anleitung zur Reinhaltung der Luft, in short referred to as TA Luft, is a regulation covering air quality requirements—including emissions, ambient exposures and their control methods—applicable to a number of pollutants from a range of stationary sources. The TA Luft regulation, based on the “Federal Air Pollution Control Act” (“Bundes-Immissionsschutzgesetz”), has been introduced and is enforced by the German Environment Ministry BMU (Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit).

Among other sources, the TA Luft regulation covers emissions of pollutants from stationary internal combustion engines. The TA Luft requirements have been widely applied to stationary gas and diesel engines not only in Germany, but also in several other European markets.

The TA Luft regulation was first introduced in 1986. The most recent revision, known as TA Luft 2002, was adopted on 24 July 2002. Compared to the previous requirements, TA Luft 2002 has introduced more stringent emission limits for particulate matter, sulfur oxides, and nitrogen oxides from internal combustion engines.

Engine Emission Standards

TA Luft 2002 emission limits for PM, CO, and NOx are given in the following tables. Different limits exist for compression ignition (CI) and for spark ignited (SI) engines. Gas fueled CI engines (dual fuel with diesel pilot ignition) often enjoy more relaxed limits, especially if fueled by biogas (such as sewage or landfill gas).

Table 1
PM Emission Limits for Internal Combustion Engines, mg/Nm3 @ 5% O2
CategoryPM
CI liquid fueled20
CI liquid fueled stand-bya80
CI gas fueled (dual fuel) or SIno limit
a - emergency operation only or peak shaving operation for less than 300 hrs per year
Table 2
CO Emission Limits for Internal Combustion Engines, g/Nm3 @ 5% O2
CategoryCO†
≥ 3 MW< 3 MW
All, excluding biogas and mine gas fueled0.3
CI biogas (dual fuel)0.652.0
SI biogas0.651.0
SI mine gas0.65
† CO limits do not apply to emergency engines or engines used for peak shaving for less than 300 hrs per year
Table 3
NOx Emission Limits for Internal Combustion Engines, g/Nm3 @ 5% O2
CategoryNOx†
≥ 3 MW< 3 MW
CI liquid fueled
CI biogas (dual fuel)
0.51.0
SI biogas or SI lean-burn using other gas fuels
CI (dual fuel) using other gas fuels
0.5
Other 4-stroke Otto engines0.25
2-stroke engines0.8
† NOx limits do not apply to emergency engines or engines used for peak shaving for less than 300 hrs per year

All of the above engine emission limits are expressed as dry gas concentrations at STP conditions, that have been corrected to a 5% oxygen content using the following formula:

EB = EM × (21 - OB)/(21 - OM)

where:
EB - mass concentration of pollutant corrected for the reference O2 concentration,
EM - measured mass concentration of pollutant,
OB - reference O2 concentration, vol. %,
OM - measured O2 concentration, vol. %.

The TA Luft 2002 limits for diesel engines are rather strict. The NOx limit of 0.5 g/Nm3 typically requires the use of SCR catalysts on large diesel engines.

Sulfur Regulations. According to TA Luft 2002, a liquid fired stationary engine is to burn a light fuel oil according to DIN 51603 Part 1 (March 1998) containing max. 0.2% (wt.) sulfur and with a lower heating value > 42.6 MJ/kg, or to reach an equivalent SO2 limit by installing a flue gas desulfurization unit. The equivalent SO2 limit resulting from the above fuel requirement is about 110 mg/Nm3 @ 15% O2 = approx. 300 mg/Nm3 @ 5% O2.