Whether they operate in the air, on the ground, or at sea, gas turbine engines must deliver safe and reliable operation, high efficiency, and environmentally acceptable emissions. However, engines designed specifically for each of these applications have different environmental impacts and operating constraints that affect the range of technologies that can reasonably be applied and the type of emissions regulatory framework that is best suited to regulate their design, qualification, and operation.

Aero and Industrial Engines – Contrasting Requirements

Aero and ground-based engines can have many similarities. In fact, industrial engines derived from aero engines (aeroderivative engines) are used extensively in industrial service. However, technologies have been applied to industrial engines such that emissions from the lowest-emitting versions of the industrial engine are at least an order of magnitude lower than the original aero engine. These emissions reductions are achieved in a number of ways:

• Natural gas fuel reduces conventional combustor NOx emissions by nearly 50 percent compared to jet fuel, primarily by reducing adiabatic flame temperature.

• Water injection or use of dry low-emissions combustor technology reduces remaining NOx by approximately 90 percent.

• Catalytic exhaust gas cleanup reduces what emissions are left by approximately 90 percent.