CHICAGO, March 22 (Reuters) - Costs are the main

obstacle to increasing the use of sustainable aviation fuel

(SAF), Exxon Mobil ( XOM ) Senior Vice President Jack Williams

said on Friday.

SAF, a biofuel made from plant or animal materials including

used cooking oil or agricultural waste, can reduce carbon

emissions by up to 80% compared with traditional jet fuel. But

it is up to five times more expensive than regular fuel.

"There's one big negative and that's the cost," Williams

said at a conference near Chicago. "As we think about how we

want to grow SAF ... we have got to focus on how do we minimize

the costs."

Williams described the Biden administration's Inflation

Reduction Act as the catalyzing action for biofuel production as

well as carbon capture and storage and low carbon hydrogen.