With advocacy groups demanding cleaner air and governments passing more and more stringent engine emissions requirements, aviation has been taking a beating as a prime offender in creating carbon emissions.

However, aviation can claim with justification that it accounts for only about 2 percent of global carbon-dioxide emissions. But facts have never gotten in the way of the mobs with causes, or public officials running for re-election. And the hard truth is that fossil fuels are non-renewable and a finite sources of power, though no one can define exactly how finite they really are.

Nevertheless, in the past five years, the aviation industry has taken a leadership role in the development of technology, engineering and alternative fuels that will produce fewer greenhouse emissions.

Engine manufacturers have invested heavily in such technology as lean-burn/low emissions combustors, open-rotor or unducted fans, new composites for fans and casings and advanced airfoil designs for fan blades.

GE, Honeywell, MTU Aero Engines, Pratt & Whitney Canada, Rolls-Royce, Snecma and Williams International are pushing hard to produce more efficient and more environmentally friendly engines.

Honeywell is also investing in alternative fuel itself, developing what it calls “Honeywell Green Jet Fuel.” This summer, the company flew its corporate Gulfstream G450 from Morristown, N.J. to the Paris Air Show, making history with the first transatlantic flight using biofuel. The number-one engine burned a 50-50 blend of Honeywell’s biofuel and standard jet-A, while number two consumed only jet-A, and the result was a net equivalent savings of roughly 5.5 metric tons of CO2.

As better feedstock is found to produce biofuels more efficiently and in greater quantities, these alternative fuels will slowly replace the current jet-A derived from underground fossil fuels. They must, but it won’t be tomorrow.

James Rekoske, Honeywell v-p and general manager of renewable energy and chemicals, said he thinks the common use of a 50-50 blend of biofuel and jet-A by aviation worldwide is not likely to occur within the next 30 years.

In the meantime, aviation is definitely going green, or at least greener, with the development and introduction of cleaner, more fuel-efficient engines, and better alternative fuels, which produce fewer greenhouse gases.