The smokestacks that have loomed for decades over South Boston could soon be coming down.

Exelon Corp. has put the old Boston Edison power plant at the corner of Summer and First streets — now known as the New Boston Generating Station — up for sale, probably for re-development.

At least a half-dozen developers have bid on the 18-acre site, according to people familiar with the sale. While reuse plans haven’t been made public, experts say any winning bidder would likely turn the little-used power plant into a mix of housing and commercial space. An Exelon spokesman said they hope to close a deal this year.

“The sale has generated considerable interest from the development community,’’ said Exelon spokesman Marshall Murphy.

It’s a rare opportunity: 18 acres of waterfront property along the Reserved Channel, near the Summer Street Bridge to the Seaport District, and on the edge of booming South Boston. And some of the site — several huge buildings cobbled together over decades — could be preserved, with its brick walls and soaring arched windows along First Street.

“It’s a spectacular building,’’ said Brian Golden, director of the Boston Redevelopment Authority. “If you could reutilize the structure, it could be magnificent.’’

The re-purposing of old power plants has become more common in recent years, from an Art Deco-plant turned office space in Austin, Texas, to the ongoing redevelopment of London’s Battersea Power Station — which belched smoke on the cover of a Pink Floyd album in 1977 — into multi-million-dollar condos.

But re-using a building that served as an active power plant for more than a century comes with a host of challenges.

It was built in 1892, first to burn coal, then oil, then natural gas. It has long been a Southie landmark. It was largely retired in 2007, though Exelon still turns on a small generator during periods of peak electricity demand.

There have been numerous spills and other chemical releases on the property, and state and federal environmental officials have been monitoring its cleanup in recent years, including the removal of oil tanks and 4,500 tons of contaminated soil.

Last year, the US Environmental Protection Agency reported that the cleanup was complete and health and environmental risks were “adequately addressed,’’ at least for its current use as a power plant.

Other uses could be limited, at least on portions of the property.

In 2001, the Massachusetts Department of Environmental Protection issued an order blocking use of part of the site for housing, a spokesman said, but noted that could change with further cleanup. The EPA report said that some portions of the property could yet face further limits, which would be set later this year.

Exelon said it has fulfilled its environmental obligations and would not comment on future use.

“New Boston Generating Station’s reportable environmental conditions have been closed or are in the later stages of regulatory closure,’’ Murphy said. “Exelon is not in a position to speak to what the redevelopment of the site would involve.’’

Another wrinkle could be a freight road the Massachusetts Port Authority plans to build across the property to take truck traffic from the nearby Conley Terminal off First Street. The project includes a small bridge that would span the water in front of the property.

Even with the plant’s history, and potential limitations, the opportunity to turn the site into something new would be attractive to developers, said David Begelfer, chief executive of real estate trade group NAIOP Massachusetts.

“It’s a large enough site that you have the critical mass to do something major,’’ he said. “It’s right on the water. It has a lot of attributes that make it unique.’’

Most likely, Begelfer said, it would be redeveloped as a mix of office and residential space, taking advantage of both its proximity to the employment centers of the Seaport District and the demand for new housing in Boston.

Golden said that no potential buyers have yet come in to talk with his agency about the site’s possible reuse and that BRA’s ideas for it are, at this point, “embryonic.’’

But, he said, it’s a giant piece of land, in a desirable location.

“There’s something good that’s economically feasible that can be done on that site,’’ he said.

What that is will likely be sorted out over the next couple of years. But it almost certainly won’t involve the giant smokestacks that loom over First Street.

Tim Logan can be reached at tim.logan@globe.com.