Just about four years ago, Sunoco, the Philadelphia company that had been importing crude oil at often punishing profit margins to keep its aging Delaware River refineries open, was giving up on the business. But the surge in North American oil supplies from tar sands, fracking and other new technologies, exploited by energetic new owners who have taken over from Sunoco and other local refiners -- Carlyle Group, Delta Airlines, PBF Energy -- have given the old industry new clout in Washington -- against its biofuel rivals, among others.

But not all the local business or political establishment is lined up with Big Oil. The DuPont Co. in Wilmington has joined with rival plant and pesticide developer Monsanto, grain shippers, and farm industry groups to support federal policies that favor biofuels, including ethanol. More on that below.

The local oilmen proved their clout last year when they prevailed on Philadelphia Democrat U.S. Rep. Bob Brady to urge Vice President Biden to help delay Environmental Protection Agency guidelines mandating the use of more ethanol (corn-based alcohol) and less gasoline in motor fuels last year. "In this battle between Big Oil and Big Corn, the Philly refiners have been the most effective players in the fight," Reuters reports, after comparing White House lobbying records to changes in federal fuel policy and ethanol costs.

Brady was joined in the cause by U.S. Rep. Patrick Meehan (R., Pa.). They had worked together on the campaign to recruit the new refinery operators, after Sunoco and other old-time refiners gave up and shut down. Brady's staff says he's not against all biofuels, just ethanol. He agrees with oil lobbyists that it's a wasteful use of corn.

But at last week's Biotechnology Industry Organization show at the Pennsylvania Convention Center, Big Oil was slammed as a barrier to planetary progress.

"The oil-refining industry is trying to discourage development of biotech infrastructure," charged Jim Greenwood, the former Republican congressman from Bucks County, in the group's plenary session Tuesday.

"Just like Thomas Edison and his allies fought off (Standard Oil Co. monopolist John D.) Rockefeller's attempt to derail electricity, we are fighting off efforts to stop renewable fuels," Greenwood thundered. "And I promise we will be as successful."

One of the week's honorees, DuPont chief executive Ellen Kullman, rose next to tell how her predecessor at DuPont, Charles "Chad" Holliday, drafted her 15 years ago to unite chemists and industrial biologists to turn science research into real-world products. The chemists felt "threatened" by biotech. The biotech people's "veins used to bulge when the chemists came into the room," Kullman recalled. But they learned to cooperate. And DuPont was determined to shed drug and chemical businesses to "follow the science" into biotech, Kullman said.

The hardest part, Kullman added, has been building a new supply chain linking raw materials, developers, engineers, processors, marketers, and distributors. "We're competing with petroleum-based supply chains that have had 100 years to figure it out," she said.

Kullman cheered DuPont's advances in cellulosic ethanol, which uses wood or weeds or farm waste instead of corn. But she also defended the EPA's rising ethanol mandate: "I call on Congress to renew it," she said. "It is about reduced dependence on fossil fuel. It is about independence. It is about jobs. I like that kind of return on investment."

But even when a new technology is superior, it's hard, and costly, to change old habits, minds, and relationships, Kullman said. So hard, she added, that "great change in technology can't occur without government support."