In America’s highly polarized political debate, a rare consensus is emerging among presidential candidates that America needs to stop using foreign oil and move on, instead, to other energy sources.

“Energy independence, I think, is the single most important thing that’s going to face us in the next four or five years aside from the terrorist war on us,” the candidate leading the Republicans in nationwide polls, Mayor Giuliani, has said.

Senator Clinton, who polls indicate is leading the Democratic field, describes her support of policies that would “increase our energy independence, create jobs, and provide cleaner, more reliable energy.” Another Democratic contender, Senator Obama of Illinois, has said, “If we hope to strengthen our security and control our own foreign policy, we can offer no less of a commitment to energy independence” than the national effort to defeat the Soviets in space.

Mayor Bloomberg, a possible independent candidate for president, in a radio address said, “This constant dependence on oil is something that leaves this country vulnerable every day.”

Politicians and advocates say that getting America off of imported foreign oil would have a foreign policy advantage by cutting the flow of funds to regimes such as Iran, Saudi Arabia, and Venezuela that are seen as anti-American, un-democratic, or supportive of terrorists. They say it would have environmental advantages by possibly reducing emissions that have been blamed for global warming. And there are populist political advantages in appearing to side with American consumers who are upset by gasoline prices that are sharply higher than they were a few years ago.

A goal of total American independence from foreign oil may be too ambitious. A professor of economics at Harvard University, Martin Feldstein, told The New York Sun by e-mail that America would be dependent on imported oil for the indefinite future. Mr. Feldstein, chairman of the Council of Economic Advisors during the Reagan administration and a participant in a recent Council on Foreign Relations on “National Security Consequences of U.S. Oil Dependency,” said, “While we cannot eliminate oil imports, we can reduce the volume.”

Even that would be a sign of a new political and economic landscape that is prompting old-line oil companies to re-allocate their resources and driving new investments in other energy technologies that all have their own drawbacks.

Left and Right ‘Strange Bedfellows’:
Calls for energy independence have created a political alliance between some environmentalists on the left and anti-terror hawks on the right. This makes for “strange bedfellows,” said the executive director of the Institute for the Analysis of Global security, Gal Luft.

A research analyst with New Energy Finance, Ethan Zindler, said that labels of Republican and Democrat are starting to mean less when it comes to energy.

The chair of the Set America Free Coalition, Ann Korin, said having the National Resources Defense Council in the same room as a former Republican presidential candidate known as a Christian Conservative, Gary Bauer, is “rather unusual.” But evangelicals and conservatives are getting involved in a cause that once might have been left to Democratic-leaning groups such as the Sierra Club. The Evangelical Environmental Network, for example, has a project called “What Would Jesus Drive?”

A former director of Central Intelligence, R. James Woolsey Jr., who is known as a neoconservative, drives a hybrid car and touts plug-ins. A lecturer at University of Pennsylvania, Nadivah Greenberg, who is writing a book called “The Green and the Right: Environment in American Conservative Thought,” anticipates that more conservatives — though presently “outliers” — would express a green sensibility in the coming years. She believes an enduring strand of conservative thought stressing stewardship and frugality exists that is compatible with environmentalism. Richard Nixon founded the federal Environmental Protection Agency and Theodore Roosevelt was an early conservationist. “It’s a huge tent,” she said.

Mr. Luft said that every year he has seen a stronger alliance of politicians on the right and left favoring energy independence. He said that although they agree on a menu of choices, “what is less clear is how much will be actually implemented.” Mr. Luft said America’s current dependence on foreign oil results in sending huge sums to countries such as Saudi Arabia, which end up funding radical Islam. “We end up paying for both sides of the war on terrorism,” he said.

But the idea that reducing oil consumption helps national security has critics, too. A senior fellow at the Cato Institute, Jerry Taylor, said there was no correlation between oil revenue and terrorism. He said that the low price of oil during the 1990s was no barrier to the rise of Islamic terror. Somalia, Pakistan, and Afghanistan were not oil rich states, and besides, he said, the terrorist attacks on September 11 were only a “$400,000 operation.”

How Much Oil is Left?:
One continuing eddy in the policy debate over America’s oil dependency is the empirical question of how much oil actually remains in the earth. A senior fellow at the Manhattan Institute, Peter Huber, who co-authored the book called, “The Bottomless Well: The Twilight Of Fuel, The Virtue Of Waste, And Why We Will Never Run Out Of Energy,” said if one includes tar sands, one will not run out of oil for centuries. “There is no shortage of buried hydrocarbons that can be refined into oil,” he said.

A professor at the University of Albany, Pradeep Haldar, said the controversy is over not whether but when America will deplete its oil.

Large Oil Companies Take Notice:
The winds of change have affected even the big oil companies. Major oil companies such as ExxonMobil and BP (Once “British Petroleum,” now, according to its advertising, “Beyond Petroleum”) are showing increasing interest in alternative energy. A BP spokeswoman, Sarah Howell, said that BP had launched a company called BP Alternative Energy in November 2005. BP is investing $8 billion over ten years into low-carbon technologies like wind, solar, and hydrogen power, she said.

Asked what BP would do if oil runs out, she said this would be faced “eventually, someday” but this was the “very long term.” She cited estimates that there were 60 or more years left of natural gas and 40 or more years of oil left, given today’s technology. She said BP believed it was a good business decision to invest in alternative energy since customers wanted these products. She said the investment in alternative energy was an acknowledgment that they were able to address the issue of climate change.

The director of the center for business law and regulation at Case Western Reserve University School of Law, Jonathan Adler, said the major oil companies were transforming their rhetoric and marketing, not necessarily their practices or investments. A senior researcher at the Rand Corporation, James Bartis, said major oil companies were investing in alternative energy to stay on top of various options. He said these niche markets can also be profitable and that the companies are aware that governments may put in place new laws that fundamentally change the ranking of different energy options.

Ethanol:
Mr. Haldar said there was no single solution for energy independence, but it would involve multiple approaches, including hydrogen, solar, and ethanol.

Although ethanol has support among many environmentalists, increased use of ethanol can create adverse consequences as well. An attorney and former deputy secretary of the U.S. Department of Energy under President George H.W. Bush, Linda Stuntz, said one drawback is that it may cause farmers to remove land from conservation reserves, fertilizer the land and cultivate it. A founder of Riverkeeper, Robert Boyle, said that fertilizer runoff down the Mississippi — what Mark Twain called the colon of America — has created a dead zone of oxygen depletion in the Gulf of Mexico.

Mr. Taylor of the Cato Institute said that even if all the corn produced in America last year were dedicated to ethanol, it would reduce U.S. gasoline consumption by only 12%.

Another drawback is the shift in increased ethanol consumption in the past six months has sent corn prices upward. “There’s more demand for the same amount of crop,” said a professor of environmental economics at Pace University, Eugenie Bietry.

Solar Mr. Haldar of the University of Albany said if America does not invest in solar technology, the Chinese will be selling solar panels to America, and “we’ll be shifting our energy supply from Saudi Arabia to China.”

Mr. Adler of Case Western Reserve University said that solar had a lot of really useful applications but was never going to power a whole city like New York. One drawback is that solar energy, like wind energy, is intermittent and delivered only when the sun shines. But Mr. Haldar said that is why solar is good for addressing not base load demand but peak power demand needs of New York City, for example, where electricity usage follows air conditioning demand.

Mr. Bartis, of Rand, said that solar has great potential but currently was extremely expensive when compared to power generated from coal, natural gas, nuclear energy, wind or biomass. The director of Pace Law School’s Energy Project, Fred Zalcman, said likewise that for now the major limitation for solar energy was economic: “The homeowner/ business owner has to make a relatively large up-front investment in the system to secure a longer-term stream of savings (avoided electric bills).” Mr. Bartis said there were downsides to every energy option that he knew of. He said that for example, the manufacture and eventual disposal of solar panels might involve releases of toxic materials.

Nuclear:
Many academics are not particularly optimistic as to the prospect of nuclear power replacing oil. Mr. Adler said, “If we can’t site windmills off Cape Cod, how are we going to site a nuclear plant?” He was referring Cape Wind, a proposed offshore wind farm six miles from the shore of Hyannis Port that environmentalist Robert F. Kennedy Jr. and others have opposed.

Activists such as Susan Shapiro of Rockland Friends United for Sustainable Energy said the “No Nukes” movement is “stronger than ever.” She opposes re-licensing Indian Point in Buchanan, N.Y. But the actor Paul Newman toured the plant in May and praised its safety.

Mr. Boyle, a founder of Riverkeeper, said he doubts nuclear plants are the wave of America’s future. He said Three Mile Island and Chernobyl are etched into America’s psyche. Others fear that nuclear plants remain an attractive target for terrorists.

But Mr. Huber of the Manhattan Institute said there is renewed interest in nuclear energy in England. He said if one wants to see unusual alliances, consider how nuclear power advocates have supporters such as Gaia theorist, James Lovelock, who advocates clean nuclear energy to halt global warming. Closer to home, a co-founder of Greenpeace, Patrick Moore, has teamed up a former Environmental Protection Agency director, Christine Todd Whitman to lead the Clean and Safe Energy Coalition, advocating nuclear power as a way to ensure clean air quality.

Looking Forward:
Regarding oil independence, Republicans and Democrats may be converging more, but regional differences will likely play a role in future debates about renewable energy. For example, farm states actively support ethanol, said the director of the Urban Energy Project at Columbia University’s Center for Energy, Marine Transportation and Public Policy, Stephen Hammer.

Elected officials in the southeast tend not to favor bills supporting wind energy, because they have less of that resource in their home states. So while there is a consensus about reducing dependence on foreign oil, there is little agreement on exactly what to replace it with.

Tomorrow: The business of alternative energy.