* Green diesel made by transforming oils, fats into fuel
* Costs about the same and can be blended with jet fuel
By Nina Chestney
LONDON, Jan 14 (Reuters) - U.S. aircraft maker Boeing Co. aims to seek approval from regulators around the world to use "green diesel" as a jet fuel, the company said, which could cut carbon emissions without boosting costs.
Green diesel is made from oils and fats such as used cooking oil, plant oils or waste animal fats in a process that uses hydrogen to break big molecules into smaller ones.
It is also known as "renewable diesel" and can be used in any diesel engine. It differs from biodiesel, however, which is produced by a chemical reaction between vegetable oil and alcohol.
"Green diesel approval would be a major breakthrough in the availability of competitively priced, sustainable aviation fuel," said James Kinder, technical fellow in Boeing's Commercial Airplanes Propulsion Systems Division, said in a statement on Tuesday.
The wholesale cost of green diesel is around $3 a gallon including government incentives, which is about the same as for oil-based jet fuel and cheaper than other biofuels, Boeing said.
Researchers at Boeing have found that green diesel can be blended with oil-based jet fuel, the company said. Proof is needed that its efficiency and reliability are comparable with traditional fuel.
The aviation sector accounts for about 2 percent of global greenhouse gas emissions, and that share is expected to grow to 3 percent by 2050 without moves to control emissions.
Green diesel emits at least 50 percent less carbon dioxide than fossil fuels over its lifecycle, according to Boeing.
Since 2011, some airlines such as Lufthansa and Continental Airlines have been using alternative biofuels made from the jatropha plant or from algae for commercial flights on planes made by Boeing and European rival Airbus.
Boeing is working with the U.S. Federal Aviation Administration, engine manufacturers and green diesel producers to pave the way for its approval as a jet fuel.
"We are collaborating with our industry partners and the aviation community to move this innovative solution forward and reduce the industry's reliance on fossil fuel," Kinder said.
Green diesel production capacity already exists in the United States, Europe and Singapore that could supply up to 1 percent - about 600 million gallons - of global commercial jet fuel demand a year.