Mid-sized Combustion Plants

In the Netherlands, requirements for mid-sized combustion plants are laid down in the Activities Decree. The Decree sets emission limit values (ELV) for NOx, SOx, PM and CxHy (based on best available techniques) and gives provisions on maintenance.


The Activities Decree applies to installations with a nominal capacity over 400 kW; with regard to biomass installations, the Activities Decree applies irrespective the nominal capacity. For gas turbines and stationary engines, there is no minimum input rate. The ELVs depend on the type of plant (boiler, engine or gas turbine) and the type of fuel used (solid, liquid or gaseous). New plants must meet the ELVs now. Existing plants must meet the limit values from 2017.

In the Netherlands, an increase in the use of biomass is expected. For that reason, ELVs are given for the use of biomass in wood-fired boilers and bio-oil fired engines, for example.

Emission limit values with SCR

The ELVs for NOx for natural gas-fired stationary engines are important parts of the Activities Decree. In the Activities Decree, ELV is further tightened to 100 mg/Nm3. This ELV plays an important role in reducing industrial NOx emissions. About 10% of the electricity in the Netherlands is generated by gas engines in a CHP application (Combined Heat and Power). To meet the ELV, a SCR (Selective Catalytic Reduction) is needed. In the Netherlands, SCR is considered as BAT. This technique is often applied in In the greenhouse horticulture.

Monitoring requirements

The monitoring requirements are performed by separate measurements. For boilers, a single set of measurements is required once the ELVs have come into force. Measurements for engines and gas turbines are also required after the ELVs have come into force, and measurements should be repeated every four years. Measurements should be performed by an accredited laboratory. For certain NOx abatement techniques, however, continuous measurements are required. Continuous measurements should meet the requirements of the quality assurance standard EN-14181. The background information is provided in the Manual Measurement of air emissions.

Installation NOx Dust SO2 CxHy
Boiler (Biomass) <400kWn 300 40 200
Boiler (l) 400kW - 1MW 120 20 200
Boiler (Biomass) 400kW - 1MW 300 40 200
Boiler (natural gas) 400kW - 1MW 70 200
Boiler (s) ≥1 MW(n) 100 5 200
Boiler (l) ≥1 MW(n) 120 5 200
Boiler (Biomass) 1 - 5 MWth 200 20 200
Boiler (Biomass) ≥5 MWth 145 5 200
Boiler (g) ≥1 MW(n) 70 200
Diesel engine (l) 450 50 200
Gas engine (g) 100 200 1500
Gas engine (biogas or <2.5MWth) 340 200
Gas turbine (l) 140 15 200
Gas turbine (g) 140 200

Emission limit values: s:mg/Nm3 @ 6 vol%O2; l+g:mg/Nm3 @ 3 vol% O2
MWth: Thermal input rate in MW
MWn: Nominal heat output in MW