United Airlines ready to make first regular poop-powered passenger flight

United Airlines is all set to power some of its passenger jets with poop.

No, it doesn't mean the bathrooms' plumbing systems have been rerouted to the engines. This is all to do with biofuel, and involves animal, not human, waste.

The plane, which will operate with 30 percent biofuel blended with 70 percent regular jet fuel, is set to make regular flights between Los Angeles and San Francisco. According to the New York Times, the journey marks the first time for an airline to use alternative jet fuel for regular passenger flights.

United plans to make around five flights a day between LA and San Francisco with planes powered by biofuel supplied by Californian company AltAir.

The carrier's plan to reduce greenhouse gas emissions through the use of biofuel also includes a $30 million investment in Fulcrum BioEnergy, one of the world's leading suppliers of aviation biofuels. The deal with Fulcrum is expected to be announced by United today.

Debbie Hammel of the Natural Resources Defense Council told the NY Times there was a "significant role" for biofuels in the aviation industry, "specifically for reducing carbon emissions."

Airlines currently account for around 2 percent of global carbon emissions, but as things stand the industry is one of the fastest-growing sources of such pollution. Fulcrum says its technology can reduce carbon emissions by as much as 80 percent.

United isn't the only airline making major moves toward biofuels. Last year British Airways, for example, said it'd partnered with Solena Fuels to construct a biofuel refinery close to London's Heathrow Airport, with work expected to be completed within two years. Alaska Airlines and Southwest Airlines have also announced plans to start using biofuels for some of their aircraft.

As for passengers, they shouldn't notice anything different during the flight. For sure, any challenging odors filling the cabin will more than likely be emanating from the bathroom rather than the engines.