Shari Williams, wife of Philadelphia mayoral candidate and state Sen. Anthony Hardy Williams, last week defended her lucrative work for a major oil and gas lobbying group.

She emphasized that her husband was not influenced politically by her job as a community outreach coordinator for the Marcellus Shale Coalition. Both wife and husband said the senator has long independently supported Philadelphia's potential to become a major processing hub for shale gas.

The popular term these days: "energy hub."

"Of course we'd both like to see Philadelphia become the next energy hub," Shari Williams said, in a phone interview. "I think all the [mayoral] candidates support that."

But not all the candidates flatly support it. Nelson Diaz said he has reservations about the side effects of greatly expanding the energy industry in the city and questioned Anthony Williams' objectivity toward the environmental issue, considering Shari Williams' job.

Do Williams' other rivals support the idea of Philadelphia becoming Dubai-on-the-Delaware? While Shari Williams was speaking off-the-cuff, she wasn't too far off about two of her husband's strongest opponents.

"Philadelphia has significant access to natural gas resources, so Jim believes it's a matter of 'when,' not 'if', our city becomes an energy hub. He feels that the sooner the city gets involved the more influence they'll have over the responsible development of those resources.," said Lauren Hitt, spokeswoman for City Councilman-turned-mayoral candidate Jim Kenney. "Jim would work to ensure that our city has a healthy balance of renewable and traditional energy jobs, that those jobs go to Philadelphians."

In other words, Kenney is striking a pose that is fairly similar to Williams, who last week said he supported energy processing in Philadelphia for its potential to create blue collar jobs.

Kenney's stance is not altogether surprising, considering his ties to South Philadelphia-based labor unions who would jump at the prospect of more jobs and shipping traffic to support the long-stalled "Southport" expansion along the river.

Kenney would ensure "that these resources are utilized to develop Southport as a shipping hub, and that our natural gas resources are managed responsibly and safely," Hitt said.

Southport came up recently in a City Council hearing. Phil Rinaldi, CEO of refining firm Philadelphia Energy Solutions and by far the most prominent advocate of what he calls the "Northeast Energy Hub," appeared before Council last week to promote the idea of building out Southport as a "world-class energy port."

Kenney at least has an environmental platform on his campaign website, something lacking on the sites of Williams and former District Attorney Lynne Abraham, the third prominent mayoral candidate.

On Tuesday, Abraham sang a similar tune to her opponents, if not in great detail.

"Lynne would work to transform Philadelphia into the next great energy hub — while preserving our environment and health throughout our neighborhoods and industrial areas," said spokesman Stuart Rosenberg.

Rosenberg did not outline specifically how the environment would be preserved as local refining increased, but did allude to Abraham's concerns about the transport of oil by rail.

It's a significant issue — two trains carrying Bakken crude derailed in the city last year, one in a residential section of South Philadelphia and another that was left dangling over the Schuylkill River.

Kenney expressed similar concerns, pledging to "lobby D.C." to speed up the federally-managed replacement of the city's freight lines, several of which snake through downtown Philadelphia. The aging railways have been flooded with thousands of oil trains since the gas boom.

Only candidate Diaz seriously differentiated himself from Williams, rejecting the notion that "everyone" offered the same support for the local oil and gas processing that the senator did. He said Williams' current connections to the industry raised serious "conflicts of interest."

The former judge also raised concerns about air pollution, saying that he was interested in the energy hub concept "only if it can replace, rather than add to, current or recent emissions," a campaign spokesman said.

"Judge Diaz was also proud to serve on the board of the only energy companies in the world that supports a 'Cap and Trade' system to help tackle climate change by reducing carbon emissions," spokesman Barry Caro added, speaking about Diaz's time on the board of Exelon.

While Kenney pointed to vehicle emission programs he supported as councilman, his spokeswoman suggested that increased pollution was just the cost of doing business.

"Those refineries provide thousands of working class jobs and with nearly a third of our city living in poverty that's not something we can sacrifice right now," Hitt said. "Unfortunately, clean air doesn't do our citizens a lot of good if they can't afford to live here."