NOX (and SOX) emissions are components of acid rain - when mixed with water vapor in the clouds they form nitric (and sulfuric) acid.

NOX participates in smog (photochemical ozone) formation by reacting with VOCs in the presence of sunlight - smog is a respiratory and eye irritant. NOX is primarily composed of NO and NO2, and most thermal NOX is NO.

Strategies

• Abate the formation process (reduce fuel NOx)
  • Use low Nitrogen gaseous fuels
  • Control the oxidation of nitrogen bound hydrocarbons
• Combustion modifications (reduce thermal NOx)
  • Thermal NOx is a by-product of unnecessarily high temperatures in the flame
  • Reduce flame temperature by premixing fuel and air
  • Decrease O2 content with flue gas recirculation (FGR)
• Flue gas clean-up (eliminate unavoidable NOx)
  • Selective Catalytic Reduction (SCR)
  • Selective Non Catalytic Reduction (SNCR)
  • New technologies (catalytic adsorption, wet scrubbers)