Corn is perfect on the cob. But for Alaska Air, it also makes a good biofuel.

Alaska Air used fuel based on alcohol made from fermented corn on two flights Tuesday, saying it was the first airline to do so. Both flights departed out of Seattle, with one headed to San Francisco and the other to Washington, D.C.

The flights used a fuel with a blend of 20 percent biofuel from Gevo, a company that makes biofuels for plastics and jet fuel. Gevo uses a process that converts isobutanol, an organic compound derived from ethanol, into jet fuel.

Environmental sustainability is an issue on which the aviation industry has faced heightened scrutiny in recent years. Emissions from air travel contribute just two percent of total greenhouse gas emissions worldwide, but about 12 percent of total CO2 emissions from all transportation sources, according to the International Civil Aviation Organization, a United Nations agency.

“Alaska is committed to doing its part to reduce its carbon emissions and advancing the use of alternative jet fuels is a key part of our emission reduction strategy," Joseph Sprague, Alaska Air senior vice president of Communications and External Relations, said in a press release. "Gevo’s jet fuel product is an important step forward, in that it has the potential to be scalable and cost effective, without sacrificing performance.”

The aviation industry has set ambitious goals to reduce its carbon footprint, pledging to halt increases in greenhouse gas emissions by 2020. Alaska Air estimates that it reduced greenhouse gas emissions by 50 percent by using the biofuel to power the flights. Yet Alaska is not the only airline that has considered making the switch from traditional fuels to alternative fuel sources. Other airlines are also shifting to a more sustainable path.

In March, United became the first US airline to use sustainable biofuels on a commercial scale. The airliner's regularly scheduled flights between Los Angeles and San Francisco are powered by a blend of 30 percent biofuel, produced by AltAir Fuels, and 70 percent traditional fuel. United intends to gradually phase biofuels into every flight departing from LAX.

Still, there are major obstacles to making biofuels a regular part of the airline industry. Currently, oil prices are low, reducing economic the incentive for airlines to make a switch. Additionally, biofuels can cost up to three times more than traditional fuels, according to RDC Aviation Economics.

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There is also the issue of the scale required to implement wide-scale use of biofuels to the aviation industry. Currently the production costs associated with biofuel sources such as wood pulp or palm oil is higher than the cost of traditional jet fuels. Yet RDC Aviation Economics projects that, if produced at a large scale, the costs of these biofuel sources could eventually drop to a level that makes them an attractive alternative.

However, United and Alaska Air's forays into alternative fuels may point to a future where airlines see biofuels as a viable option. Other companies are also getting in on the act. Last year, Southwest Airlines and FedEx both signed contracts with Red Rock Biofuels, a biofuel refinery, to purchase portions of its biofuel output after its refinery opened in fall 2015.