Delta Air Lines, hoping to secure a steady source of discounted jet fuel, announced Monday that it will buy the ConocoPhillips oil refinery in Trainer for the bargain price of $150 million.

The nation's second-largest commercial airline says it hopes to reduce its fuel expenses by $300 million a year with the acquisition. Delta spent $11.8 billion on jet fuel in 2011, about 36 percent of its operating expenses.

"Acquiring the Trainer refinery is an innovative approach to managing our largest expense," said Richard Anderson, Delta's chief executive officer. He said the refinery's price was the equivalent to one wide-body aircraft.

The deal, announced after the stock markets closed, was greeted with relief in Delaware County, where officials had feared the loss of two refineries simultaneously as the refining industry undergoes a severe contraction. Sunoco Inc., which owns a refinery in neighboring Marcus Hook, announced last year that it was shutting down operations.

Tom Kloza, publisher of Oil Price Information Service, said the cost was an "incredibly advantageous price."

Delta said the Corbett administration will provide $30 million in government assistance for job creation and infrastructure improvement. "Today marks an important win for southeast Pennsylvania and the Commonwealth as a whole," the governor said in a statement.

The Trainer refinery, which was idled last year, employs nearly 400 people directly, but the Governor's Office stated that the sale means the preservation of more than 5,000 jobs at the plant and in related industries.

As recently as last week, U.S. Sen. Robert Casey (D., Pa.) and local elected officials had expressed fear that ConocoPhillips would sell the refinery for use as a fuel-storage terminal, a less intensive activity than a fuel-manufacturing facility.

Delta's wholly owned subsidiary Monroe Energy L.L.C. will buy the refinery and operate it in agreement with BP and Phillips 66. BP will be responsible for locating crude oil supplies, and Phillips 66, an affiliate of ConocoPhillips, will market other fuels produced at the refinery, such as gasoline, heating oil, and diesel.

The 185,000-barrel-per-day refinery now is configured to produce 23,000 barrels of jet fuel, which is similar to kerosene. Delta will spend $100 million to reconfigure the plant to produce more jet fuel.

The acquisition includes pipelines and transportation assets that allow Delta to transport fuel to its hubs at New York's LaGuardia and John F. Kennedy airports.

East Coast refining has been under pressure because of poor profit margins and declining markets for motor fuel, and the Trainer plant is one of one of three Philadelphia refineries that faced closure. Sunoco Inc. is in talks with the Carlyle Group to operate its Philadelphia refinery as a joint venture, though it says it has been unable to find a buyer for the Marcus Hook refinery.

The Trainer refinery will be run by a 25-year refinery veteran, Jeffrey Warmann, who was refinery manager for Murphy Oil USA Inc.'s refinery in Meraux, La. Warmann led Meraux's restructuring efforts and increased refinery output by more than 30 percent and "significantly improved" Meraux's profitability, Delta said.

The deal is expected to close by June 30, with jet fuel production to begin in the third-quarter, and result in a fuel savings this year of more than $100 million, the airline said.

Some analysts had expressed skepticism about the wisdom of an airline diversifying into oil refining, a notoriously cyclical, capital-intensive business with low margins. But Michael Linenberg, an airline analyst with Deutsche Bank Securities, recently called Delta's bid "a very bold move."

Contact Andrew Maykuth at 215-854-2947 or or follow on Twitter @Maykuth.