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Emission Standards

Stationary Engines—Gothenburg Protocol


The “Protocol to Abate Acidification, Eutrophication and Ground-Level Ozone” was signed in 1999 in Gothenburg, Sweden, as an extension to the United Nations’ 1979 Geneva Convention on Long-Range Transboundary Air Pollution. The Gothenburg Protocol entered into force on 17 May 2005.

The following are the main provisions of the Protocol:

  • Emission ceilings are adopted for 2010 for four pollutants: sulfur, NOx, VOCs and ammonia. Different ceilings values (in tons/year) have been adopted for different countries, as negotiated on the basis of the emissions environmental or health impact and emissions reduction costs. Once the Protocol is fully implemented, Europe’s sulfur emissions should be cut by at least 63%, NOx by 41%, VOC by 40%, and ammonia by 17% compared to 1990.
  • Limit values for specific emission sources are established, such as combustion plants, electricity production, cement production or dry cleaning. Best available techniques are required to control emissions. Guidance documents adopted together with the Protocol provide a range of abatement techniques and economic instruments for the reduction of emissions. Among the specific emission sources, the Protocol establishes NOx emission limits for large stationary engines. Emission limits for new stationary sources should be enforced within one year after the date of entry into force of the Protocol for the party in question.
  • Maximum sulfur content is specified for gas oil fuels (other than fuels used in vehicles) at 0.2% effective 2000.07, and 0.1% from 2008.01.

The Protocol has been signed by a number of European countries, one Asian country (Armenia), as well as by Canada and the USA. However, in most cases Canada and the USA have different emission reduction provisions than those for the other parties.

Engine Emission Standards

NOx emission limits for new stationary engines specified by the Gothenburg Protocol are listed in Table 1 (applicable to all parties other than Canada and the USA).

Table 1
NOx Emission Limits From New Stationary Engines
DescriptionNOx Limit, mg/Nm3
Spark ignition (Otto) engines, 4-stroke, > 1 MW
Lean-burn engines250
All other engines500
Compression ignition (Diesel) engines, > 5 MW
Fuel: natural gas (jet ignition engines)500
Fuel: heavy fuel oil600
Fuel: diesel oil or gas oil500

NOx is specified as NO2 equivalent. Concentrations are expressed at standard temperature and pressure conditions (273.15 K, 101.3 kPa) and at an oxygen reference content of 5%.

The limits do not apply to engines running less than 500 hours a year. Start-up, shutdown and maintenance of equipment are also excluded. Meeting the limits by lowering exhaust concentrations through dilution is not permitted.

The Protocol also specifies emission monitoring and reporting requirements.