Throughout its multi-decade history, the commercial airline industry worldwide has seen human resources as its primary expense; in contrast, jet fuel has always been a nontrivial cost, yet never a significant threat to profitability, or even the continued existence of the carriers. But in this tumultuous new environment of dwindling global oil production, sharply rising fuel prices, and governmental mandates to reduce carbon emissions, the airlines of the industrialized countries — the United States especially — are under pressure to find alternatives to the kerosene that has traditionally powered their aircraft.
Ethanol is frequently touted as a viable and eco-friendly replacement for kerosene, particularly by American farmers, who stand to gain the most by ethanol legislation (and subsidies and tax credits). Despite corn-based ethanol possibly being the most inefficient and water-intensive alternative energy source — energy net negative, according to some impartial calculations — the corn farm lobbyists managed to convince the US Congress to push through an unwise energy bill in December 2007 that requires refineries to use 36 billion gallons of ethanol per year by 2022. Even though at least 21 billion gallons must be manufactured from nonfood raw materials, this senseless burning of food to make fuel will probably continue to push food prices much higher in the future.
Fortunately, private enterprise is not waiting for a better solution from government officials, lobbyists, or others feeding at the public trough. Four industry players — Airbus, Honeywell, International Aero Engines, and JetBlue Airways — announced on 15 May 2008 that they are teaming up to develop a second-generation of aviation fuel, "bio-jet", utilizing algae and other biomass. They hope to supply nearly 30 percent, if not more, of all commercial aviation jet fuel by 2030. The new biofuel is intended to be a fully equivalent replacement for kerosene jet fuel that will not require any engine modification, which can add considerably to overall costs.
However, critics point out that even if this consortium is able to achieve its stated aims, as long as the sizable growth rate in commercial aviation continues at its current pace, then the total amount of jet kerosene emitted into the atmosphere, will exceed even today's alarming amounts. This is partly the result of demand for air travel in foreign countries outstripping any declines in US and European travel during the ongoing economic downturn. From an ecological perspective, therefore, perhaps the only way that those emissions will truly be reduced, is for worldwide commercial air travel to decline significantly and never recover. Given that emerging markets such as China and India already have middle classes exceeding the total US population, then it is possible that the only factor that could stop the ongoing environmental damage, is for all liquid fuels to become prohibitively expensive for business and leisure jetting around the globe.