PSEG officially unveiled its new natural gas power plant in Bridgeport Monday, replacing the state's last coal-fired plant.

PSEG officials, Gov. Ned Lamont and Bridgeport Mayor Joe Ganim flipped the switch on the new plant. It took two years and 700 union workers to build it.

The head of PSEG says the change will mean a huge improvement in air quality.

"It's tenfold, if not more, on a long-term basis," says PSEG Power COO Ralph LaRossa. "This is the right -- from a bridging standpoint for us -- it's the right thing to do, to move on to a renewable economy."

The old coal-fired plant will stay online until 2021, but only as a backup. After that, Ganim says he hopes to redevelop it as waterfront property.

Technology in the new plant means it only needs a few dozen workers to operate it versus the old one, which required hundreds.

Now the question looms: Should Bridgeport's old candy cane smoke stack remain? Keeping it could hurt Sikorsky Airport's chances of bringing back passenger service because it needs a longer runway.

"There's the aesthetic value of it," says Ganim. "There are some people who say, 'Oh my God, that stack is an icon -- is a landmark if you will.'"