Generator Gas Testing

As part of The Environmental Permitting (England and Wales) (Amendment) Regulations 2018, all gensets need to be registered and get a permit. This must be done, regardless if the genset is used for standby or prime power. As part of this permitting, the emissions values of the genset must be recorded.

generator emissions gas testing

95% of black smoke is eliminated by IPU solutions


Why do I need generator emissions gas testing?

All specified generators in scope of the regulations will need permitting.

The primary purpose of the permitting process is to demonstrate that the generator site will cause no severe reduction to air quality. When applying for a permit, the NOx levels must be included to determine if they are greater than 500mg/Nm3 per year (15% O2).

Of course, many gensets will have a datasheet available with them which may include some emissions values. These emissions values may not be accurate if the genset is older, but DEFRA will accept a datasheet from the engine manufacturer.

However, it is likely many older engines will not have an emissions values datasheet available. In these cases, gas testing is essential.

After gas testing is completed, IPU will provide you with a complete written report that can be submitted with your permit.


Key permit conditions to be aware of

There are 3 key permit conditions to be aware of:

  • The Standard Emissions Limit Value (ELV)
    • As per the MCPD (see our page for more detail here), the standard ELV for nitrogen oxides is 190mg/Nm3. This Standard ELV is applicable to all generator technologies and fuels. It should also be noted that where secondary abatement is required to reduce NOx levels (i.e SCR), the ELV must be met within 20 minutes of starting.
  • A requirement that the specified generator must not cause an air quality standard to be breached
    • Where compliance with an environmental quality standard requires stricter conditions (such as protected locations, near schools, hospitals etc), then the permit will require additional controls. This may be a tighter ELV, better dispersion of emissions or reduced hours of operation.
  • There must be no persistent dark smoke emissions
    • Dark emissions, as defined by the Clean Air Act 1993, is dark smoke that is dark or darker than shade 2 of the Ringelmann Chart, described in BS 2742:2009. Black smoke is described as smoke that is as dark or darker than shade 4.


Permit compliance

Operators are required to comply with all conditions of their permits and must maintain record to prove compliance. That’s why IPU’s software comes in to play. When installing an SCR system with our in-house software (seen in the video below), you can check NOx levels at anytime, from anywhere, and pull of records to prove compliance.

If systems are not installed with our system, gas testing will help to prove compliance. IPU will provide a full written report after testing is completed which will prove emissions levels and compliance.


Video: emissions reduction in action