Just like the planes they power, biofuels are taking off.
Last year, United Airlines purchased 3.9 billion gallons of fuel.
And it cost them nearly $12 billion (and you wonder why they charge you for a little more leg room).
But starting this summer, select United flights will run on fuel made from animal fat and farm waste.
In 2013, United agreed to purchase 15 million gallons of fuel from AltAir, an alternative fuel, or biofuel, company.
AltAir's fuel, made from farm waste and natural oils, will power flights from Los Angeles to San Francisco in select test runs over the next three years.
While this is the first time alternative fuel is being used to fly the friendly skies, the technology is nothing new.
Biofuel can be made using vegetable oils or cooking oils leftover from restaurants and is available at filling stations across the country.
But this is the first time commercial airlines have gotten in on the act in a major way.
In June 2015, United announced a $30 million investment in Fulcrum BioEnergy, a California-based alternative fuel company.
This is a big deal for two reasons: One, this is the largest investment in alternative fuels by a U.S. airline, and two, unlike other biofuels, Fulcrum BioEnergy makes their product out of household garbage.
Yep, they make their fuel out of garbage. Gross, disgusting garbage.
Garbage is actually perfect for fuel because it contains large stores of carbon and hydrogen, which are the building blocks of jet fuel. Not to mention garbage is cheap and can be found literally everywhere.
As landfills rise, cities are scratching their heads to come up with a waste management solution. Fulcrum stepped in, making agreements with waste companies across North America.
About 4% of garbage landfilled annually in the U.S. winds up in Fulcrum's care.
The fuel they produce costs companies like United less than $1 a gallon — which is a great deal, considering the average cost for a gallon of non-biofuel fuel is around $2.11.
And while news of the investment is exciting, the timing isn't that surprising, given the EPA's recent announcement about regulating aircraft emissions.
United may have seen the writing on the wall, but they're not alone.
Southwest, Alaska Airlines, and British Airways have also purchased biofuels or biofuel refineries.
Alternative fuels are a way for airlines to better their bottom line and help the planet.
Biofuels make it possible for companies to save money and cut emissions, which means it's really just a matter of common sense meets business sense.
Just like the planes they power, biofuels are ready to take off.