Washington - John McCain and Barack Obama are offering voters very different views of America's energy future.

    Obama envisions the federal government funding alternative energy development and mandating lower fuel consumption. McCain sees a less direct federal role, relying on government incentives and market forces to boost energy supplies and promote efficiency.

    Both candidates are similar in one respect: They pledge a comprehensive overhaul of energy policy. But they offer sharply divergent paths that analysts often find confounding and impractical.

    "They both have ambitious goals, but less than ambitious means," said Bruce Bullock, the director of Southern Methodist University's Maguire Energy Institute.

    Richard Kearney, the director of the School of Public and International Affairs at North Carolina State University, put it more starkly: "They're just throwing stuff against a wall and seeing what sticks."

    "I'm not sure McCain has a good grasp of cap and trade" - a system that provides economic incentives to polluters to reduce emissions - "or renewables' complexities," Kearney said, "and Obama is throwing a lot of stuff out there but hasn't really set any priorities."

    Experts agreed that neither candidate's plan is likely to lower energy prices anytime soon.

    "There's no silver bullet that will bring prices down," Bullock said.

    Voters will have a particularly tough task sorting out all the ideas.

    "If I were a voter and didn't know much about energy, I would think that nothing the candidates are saying, at first glance, sounds wrong," said Robert Kaufmann, the director of the Center for Energy and Environmental Studies at Boston University.

    In addition, voters should understand "there is no singular answer. Markets are too complex and our energy needs are too great," added Philip Sharp, the president of Resources for the Future, a nonpartisan research group.

    To sort out the energy plans, experts said, voters need to consider these questions:

    • Will either plan help the United States reduce its dependence on oil?

    The United States consumes about 20.6 million barrels of oil a day. About 60 percent is imported. That's well above the 35.8 percent that was imported in 1975, when President Ford, and later President Carter, put their political weight behind comprehensive energy legislation.

    Obama aims to reduce oil consumption by at least 35 percent by 2030; among his ideas to curb demand is to increase the fleet average for cars and trucks to 49 miles per gallon in 18 years and increase it by 4 percent each year thereafter. McCain doesn't set specific goals for consumption or auto standards.

    Auto fleet-average mileage standards are scheduled under current law to increase from today's 27.5 miles per gallon to 35 mpg by 2020.

    McCain focuses on increasing oil supplies, emphasizing that his plan to end the 27-year-old moratorium on drilling off most U.S. coastal waters will free up "enormous energy reserves."

    The Interior Department estimated in 2006 that the Outer Continental Shelf could hold 115.4 billion barrels, though it also estimated that recoverable reserves off areas where production now is barred probably hold only 19 billion barrels, enough to provide about 2.5 years of U.S. consumption.

    Ken Medlock, fellow in energy studies at Rice University, sees two reasons to drill offshore: "I like the idea of being able to get supplies where we can," he said, "and you earmark the royalties (from leases) for alternative fuels."

    SMU's Bullock cited another reason: Cars are likely to remain dependent on oil for the immediate future, so finding more oil is probably a necessity.

    "To get above 35 miles per gallon, you'd have to have a complete hybrid fleet or vehicles that only ran on alternative fuel," which is unlikely, he said.

    • Can the government set energy policy on a radically different course?

    McCain and Obama say that's their goal.

    McCain would use the cap and trade system as a way to promote alternative fuels. Funds would help develop cleaner energy technologies, including nuclear power.

    The Arizona senator also would provide what he calls an "evenhanded system of tax credits" to encourage renewable-energy development "that will remain in place until the market transforms sufficiently to the point where renewable energy no longer merits the taxpayers' dollars."

    Obama, who also supports a form of cap and trade, would spend $150 billion over 10 years to help develop biofuels, "commercial-scale renewable energy," plug-in hybrids, low-emission coal plants and other exotic sources.

    The Illinois senator also pledges to double federal research funding for clean energy projects, notably biomass, solar and wind.

    Such a commitment is crucial, said David Sandalow, an energy expert at Washington's Brookings Institution, a center-left research center.

    "We need steady and dependable support for solar and wind power and other renewables," he said, "and if we do that, I think this industry will grow enormously and be a potentially huge engine of job growth over the course of the next couple of decades."

    Critics, though, see such a massive move to alternative fuels as risky.

    "If these things don't work, what's plan B?" asked Ben Lieberman, senior energy policy analyst at Washington's Heritage Foundation, a conservative research center.

    McCain's Plan B would be new oil production and electricity from what he hopes will be 45 new nuclear power plants by 2030. Obama doesn't oppose nuclear power, but makes no specific commitment to support new plants.

    N.C. State's Kearney noted one key flaw in Obama's approach: "He's opposed to dumping waste at Yucca Mountain," the Nevada site that's planned as the nation's repository for nuclear waste. Obama supports more federal research into whether the waste can be stored safely and then reused; McCain backs using Yucca Mountain for nuclear waste.

    • Can the program be sold to the public?

    The biggest energy-policy problem the new president will have is likely to be political. Massive energy programs can be a tough sell, particularly to a public that wants price relief now, and with a strong array of special interests ready to pounce.

    Yet President Carter did it in the late 1970s. It took all four years of his term, but he got about three-fourths of what he first proposed, and from the start he made it clear that his energy program was his top domestic priority.

    At the moment, said Stuart Eizenstat, who was Carter's chief domestic-policy director and is now an Obama adviser, while "there is a broad consensus something needs to be done, what's lacking is a consensus to translate that into concrete action."

    Jody Powell, press secretary to President Carter, is optimistic.

    "The next president can get something done if he keeps the package comprehensive and balanced," he said.

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    On the Web:

    Obama's energy plan

    McCain's energy plan

    US oil consumption since 1963

    Sources of US oil