Option 6: Running Dedicated Fleet of Jet Engines with Richer Fuel to Air Ratio

In this option, a fleet of dedicated aircraft is operated with the highest fuel to air ratio safely possible to generate enough soot to offset the GHG warming. For example, if 20,000 planes could generate a 1% soot release as in Option 5, then 2000 planes should produce an equivalent release by running at a 10% release and 400 planes at 50% soot. Clearly, there are engineering limits to how high a fuel to air ratio can be used and that will limit this option.

Option 7: Running High Altitude Aircraft Jet Engines with Richer Fuel to Air Ratio

In this option, dedicated aircraft that can fly at altitudes above 50,000 feet run the engines rich and generate soot. The residence time of soot is not as long as sulfate aerosol, but at these higher altitudes, a period of a year or longer is likely. As an alternative, the planes could be equipped with onboard soot generators to spare the engines and extra fuel tanks so that the flight times can be extended.

Prioritization of Sulfur/Soot Release Strategies

In the order in which they should be used:

1.     Sulfur dioxide release using dedicated fleet or high altitude planes

2.     Run engines rich on dedicated fleet or high altitude planes

3.     Run engines rich on existing commercial fleet

4.     Combination of rich fuel and high sulfur on commercial fleet

5.     High sulfur fuel only on commercial fleet

This order postpones changing the fuel sulfur for as long as possible and maintains as low a level in jet fuel for as long as possible. By using the dedicated fleets, the location for releases can be also be controlled and optimized.

Closing Remarks

Any attempt to use the jet plane option today given the uncertainties as to impacts good, bad and ineffective would have to be considered “flying blind.” But as we grow closer to a point of no return, this is a trip we may have to take anyway.