CEMS Emissions Monitoring | Calibration Gases | Coregas NZ

CEMS emissions monitoring

Continuous emissions monitoring systems are in place in many power plant and industrial combustion processes smoke stacks. CEMS instruments require many calibration gases.

The acronym CEMS refers to continuous emissions monitoring systems, which are online analysers that accurately measure the pollutant gases emitted from static industrial sources or power generation plants. To ensure measurement accuracy, CEMS instruments require periodic calibration with high precision, traceable specialty gases calibration mixtures.

Transportation combustion emissions from road vehicles and ships contain similar chemicals but are governed in a different way.

There is no common national CEMS air pollution control legislation in Australia. The EPA, or equivalent body, in each individual state or territory may set standards related to air pollutant emissions. Examples from the legislative framework for air pollution emissions control in some of the more heavily industrialised states of Australia are shown below.

New South Wales

The Department of Environment and Climate Change (DECC) is the NSW government agency responsible for air emissions legislation in NSW. The Protection of the Environmental Operations Act 1997 (the POEO Act) provides the legal basis of environment protection in NSW and within that, the Protection of the Environment (Clean Air Regulation) 2010 has been in force since September 2010.

South Australia

The Environment Protection Authority (EPA) is South Australia’s primary environmental regulator. The Environment Protection (Air Quality) Policy 1994 (amended 2005) sets the emission standards for pollutants from power plants and industrial processes.


The Environment Protection Act 1970 is Victoria’s primary environmental protection legislation. State environment protection policies (SEPPs), including the air quality management SEPP, are subordinate legislation which provide detailed requirements and guidance to implement the Act. The air quality management SEPP establishes the framework for management of air pollutant emissions from all sources in Victoria. Specific emission standards are set in Victoria Government Gazette No. S 240, of December 2001.

In Victoria there are general emissions limits for stationary sources across the state and lower emissions levels for the Air Quality Control Region surrounding Melbourne. It is also recognised in the legislation that emissions from clean fuels such as natural gas can, and should be, lower than those from liquid fuel or coal fired combustion processes. As an example, the NOx emissions from a large gas-fired power station (more than 30 MW thermal input) would be 34 ppm whereas the NOx emissions limit for a similar size gas turbine fed with liquid fuel would be more than double this at 73 ppm and the emission limit for a large coal-fired power station (more than 250 MW thermal input) is ten times the level for natural gas combustion, at 340 ppm.

Calibration gas mixtures will be required to validate the CEMS instrumentation that is used for pollution control and emissions monitoring. Combustion process control instrumentation will also require testing and calibration with certified specialty gas mixtures.