Addressing Hazardous Air Pollutant & Odor Issues for Natural Gas Fired Lean Burn Engines
The National Emission Standards for Hazardous Pollutants (NESHAP) regulations require Maximum Achievable Control Technology (MACT) when the annual mass emissions of Hazardous Air Pollutants (HAP) exceed the maximum source threshold. However, in California, HAPs are also controlled under Toxic Hot Spot Regulations which are based on health risk determinations rather than mass emissions. This creates a completely different set of problems than MACT, including which HAPs species are of concern, air dispersion, risk calculations, and refinement of catalytic control technologies. Many of these same issues must be addressed when dealing with odor complaints. SoCalGas has experiences which demonstrate the process, its pitfalls and solutions. SoCalGas also learned before spending capital on catalysts, it is best to verify catalyst performance using a corollary reactor and exhaust slip stream. Risk based analysis will become important to the entire industry as individual states drive new regulations from health laws (as opposed to air regulations) and when EPA addresses MACT residual health risk around 2012.