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Where do the emissions come from?
- The base-load boiler for wood chips, bark, pellets or peat emits dust, NOx and CO, and SO2 when peat or oil is fired.
- The recovered wood boiler is a co-incineration plant under the Swedish Ordinance on Waste Incineration (SFS 2013:253), with its own measurement requirements whatever the boiler's rated thermal input.
- SNCR for NOx gives ammonia slip. The BAT conclusions call for continuous measurement of NH3 where SNCR is used.
- Peak-load and standby boilers for oil or gas have few operating hours but their own registration and measurement requirements under the Swedish Ordinance on Medium Combustion Plants (SFS 2018:471).
Which rules apply?
| Plant | Regulation | What it means for the measurement |
|---|---|---|
| Boiler, engine or gas turbine of 1–50 MW | The Swedish Ordinance on Medium Combustion Plants (SFS 2018:471) | Registration. Periodic measurement of NOx, CO and, depending on the fuel, dust and SO2: at least every three years up to 20 MW, every year above. The first measurement within four months. |
| Plant of 50 MW or more, aggregated under the common-stack rule | The Swedish Ordinance on Large Combustion Plants (SFS 2013:252) and the BAT conclusions | SO2, NOx and dust continuously from 100 MW, periodically every six months below. BAT 4: continuously at all sizes, HCl with biomass and peat, NH3 with SNCR. AST every year, QAL2 every five years. |
| Boiler firing recovered wood or other waste | The Swedish Ordinance on Waste Incineration (SFS 2013:253) | A co-incineration plant whatever its rated thermal input: continuous measurement of dust, TOC, HCl, HF, SO2, NOx and CO, metals and dioxins at least twice a year. AST every year. |
| Production unit with at least 25 GWh of useful energy per year | The Swedish NOx charge, NFS 2016:13 | SEK 50 per kilogram of NOx. Your own NOx measurement, checked every calendar year by a comparison measurement from an accredited laboratory. Declaration by 25 January. |
The permit can set stricter requirements, and the text of the ordinances is what applies. A wood chip boiler and a recovered wood boiler at the same plant each follow their own ordinance, and both can also be covered by the NOx charge.
What is measured – and what is typical?
The limit values apply to boilers firing solid fuels under the Swedish Ordinance on Medium Combustion Plants (SFS 2018:471). BAT-associated emission levels (BAT-AELs) are the BAT conclusions' levels for well-run plants, here yearly averages for existing plants of 50–100 MW firing biomass or peat.
| Parameter | Why in this industry | Typical level or requirement | Method |
|---|---|---|---|
| Dust | Fly ash from wood chips, bark and peat | Limit value 20–50 mg/Nm3 by size and age · BAT-AEL 2–15 mg/Nm3 | EN 13284-1 |
| NOx | Formed in all combustion; the NOx charge is levied per kilogram | Limit value 300 mg/Nm3 · BAT-AEL 70–225 mg/Nm3, up to 250 with potassium- or sodium-rich fuel | EN 14792 |
| CO | Always measured under SFS 2018:471, also on standby boilers | No limit value · indicative yearly average in the BAT conclusions < 30–250 mg/Nm3 | EN 15058 |
| SO2 | Sulphur in peat and oil; forest wood fuel has no limit value | Limit value 200–400 mg/Nm3 by fuel · BAT-AEL 15–100 mg/Nm3 | EN 14791 |
| NH3 | Ammonia slip after SNCR | BAT-AEL < 3–10 mg/Nm3, 15 at varying load · continuously under BAT 4 | EN ISO 21877 |
| HCl | Chlorine in recovered wood and some biomass fuels | BAT-AEL 1–15 mg/Nm3, 25 with chlorine-rich fuel or co-firing with peat · with recovered wood: SFS 2013:253 | EN 1911 |
mg/Nm3 (dry gas at 0 °C and 101.3 kPa) at 6 % O2 for solid fuels (3 % for oil and gas in boilers, 15 % in gas turbines and engines). The upper BAT-AEL value applies as the limit value from 50 MW, and new plants have lower ranges. Emissions depend on fuel, load and flue gas cleaning.
What the measurement year looks like
Establish what applies
Rated thermal input, fuel and operating hours decide the regulation, and the monitoring programme must cover both the ordinances and the permit. A new boiler of 1–50 MW is registered and measured within four months.
Periodic measurement
We measure dust, NOx, CO, SO2 where the fuel requires it, oxygen, moisture and gas flow in one visit, at stable and representative load with the fuel that gives the highest emissions, and deliver an accredited report.
Comparison measurement for the NOx charge
Every calendar year an accredited laboratory checks your NOx measurement, the oxygen measurement and the flue gas flow against reference methods, preferably in the same visit.
QAL2 and AST on automated measuring systems
Measuring systems under SFS 2013:252 and 2013:253 are checked every year by parallel reference measurements (AST) and calibrated by QAL2 when the system is new, then at least every five years.
Performance test and environmental report
After a new build or a rebuild, a guarantee test shows whether the supplier's guaranteed emissions are met. The measurement reports are the basis for the annual environmental report, due by 31 March, and the NOx declaration, due by 25 January. Keep them for at least six years.
What is easily missed
An oil boiler that runs a few hundred hours a year is still covered by the Swedish Ordinance on Medium Combustion Plants (SFS 2018:471) if its rated thermal input is at least 1 MW. If it runs at most 500 operating hours a year it is exempt from the limit values, but it must be registered, measure CO and document the operating hours: the first time within four months of registration, then no later than after 1,500 operating hours (500 above 20 MW) and at least every five years. Plan the measurement for a period when the boiler is running anyway.
What does a measurement cost in district heating and CHP?
The price depends on the number of boilers and parameters, whether it is a periodic measurement, a comparison measurement or a QAL2 with at least three measurement days, the number of automated measuring systems, the accessibility of the measurement site and the travel distance. If you coordinate the measurements you save travel and measurement days. Request a quote – we reply within two working days. Approximate prices for the most common measurements are in the price guide.
Frequently asked questions
What requirements apply to a district heating plant with a 10 MW wood chip boiler?
The Swedish Ordinance on Medium Combustion Plants (SFS 2018:471): registration, limit values at 6 % O2 for NOx (300 mg/Nm3) and dust (50 for an existing plant, in operation by 19 December 2018, and 30 for a new one) and periodic measurement of NOx, dust and CO at least every three years. From 25 GWh of useful energy per year the NOx charge is added.
Does the comparison measurement for the NOx charge count as the periodic measurement?
No. It checks your own measuring equipment for NOx, oxygen and flue gas flow. The Swedish Ordinance on Medium Combustion Plants (SFS 2018:471) also requires measurement of CO and, depending on the fuel, dust and SO2. We do both in the same visit.
What happens if we start firing recovered wood?
The boiler becomes a co-incineration plant under the Swedish Ordinance on Waste Incineration (SFS 2013:253), whatever its rated thermal input: continuous measurement of dust, TOC, HCl, HF, SO2, NOx and CO, and metals and dioxins at least twice a year. The Swedish Environmental Protection Agency (Naturvårdsverket) assumes that recovered wood chips on the market are covered.
What are typical emissions from a biomass-fired CHP plant?
BAT-AELs for existing plants of 50–100 MW: 70–225 mg/Nm3 NOx, 2–15 mg/Nm3 dust and 15–100 mg/Nm3 SO2 as yearly averages at 6 % O2. Each plant's yearly emissions in tonnes are in the Swedish Environmental Protection Agency's register Utsläpp i siffror (emissions in figures).