Accurate Low-level Measurement of Formaldehyde Emissions from Gas Turbines

Opportunity

The EPA recently mandated the testing of formaldehyde emissions from gas turbines used for electric power generation, cogeneration, and natural gas transmission. The turbines affected by this mandate include any gas-fired, lean pre-mix, and diffusion flame units that were installed or reconstructed after January 2003, and the testing must be completed within 180 days of promulgation and annually, thereafter.

The actual emissions of formaldehyde from gas turbines are often much lower than the emission limit of 91 ppb, corrected to 15% O₂, and would therefore qualify a facility as a Minor Source of Hazardous Air Pollutants (HAPs), greatly simplifying permitting. However, standard test methods struggle to consistently measure concentrations at levels low enough to prove compliance with the emission limit due to inconsistent results and a tendency toward contamination. Furthermore, sample analysis using these standard techniques must be carried out at off-site labs, meaning results may not be received for two weeks or more.

Challenge

Montrose was contracted to measure formaldehyde emissions from existing gas-turbines to demonstrate that the emissions were far below the emission limit, enabling the facility to downsize its operating permit and thereby decrease long-term costs.

Solution

Montrose used two emerging test methods to measure formaldehyde levels from these gas-turbines of less than 10 ppb at 15% O₂, far below the regulatory limit of 91 ppb, with both techniques producing nearly identical results.  In addition, these results were produced at near-real-time.  Because these two techniques follow the criteria established in existing EPA Reference Methods for emission measurement, state and local regulatory agencies may approve these techniques, enabling the facility to qualify as a secondary source of HAPs and eliminate the need for a costly “Title V” permit.

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