Delta Air Lines is buying its own oil refinery, a novel step that it says will shave hundreds millions of dollars off its biggest expense — fuel.

The airline announced Monday that its subsidiary, Monroe Energy, has reached a deal to buy a Phillips 66 refinery in Trainer, Pa. It will pay $150 million for the facility, and get $30 million in state funds designated for better infrastructure and to create jobs.

“Acquiring the Trainer refinery is an innovative approach to managing our largest expense,” Richard Anderson, Delta’s CEO, said in a statement.

Anderson said the “modest investment,” which he likened to the cost of a new wide-body jet, would cut the airline’s fuel bill by $300 million a year.