To describe what's needed to wean the country off fossil fuels, people often use the word transition. As in "the transition to a clean-energy economy." But transition is too smooth. It suggests steadiness, even inevitability, as if the endpoint is predetermined.

The outcome of the tremendous push that's now underway to change how the United States and other countries obtain and consume energy is anything but predetermined. There are no definite answers to questions about the role one source of energy or another will play 15 or 20 years from now, no clear sense about the type of fuel (if any) people will put in their cars, no consensus on how quickly any of this can happen or at what cost.

Nor is the change likely to be smooth and quiet. Instead, it will probably be disruptive, breaking down existing ways of thinking and acting. Not that disruption is bad: Joseph Schumpeter, the famous Austro-Hungarian economist, once spoke of "creative destruction," whereby new technologies and ideas replace old ones, which themselves are overthrown by newer, more progressive ones.

Already, 2009 has been a year of visions, of prophecies. President Barack Obama's inaugural address offered one such vision: doubling alternative energy production in the next three years, updating and expanding the nation's energy infrastructure, saving billions of dollars in energy costs through improved energy efficiency. Think tanks, businesses, industry groups, and environmentalists have laid out their own plans, some more aggressive and some less so.

The sheer number of these plans, not to mention the interest percolating up from nearly all corners of American life, suggests, as Energy Secretary Steven Chu puts it, that "the landscape is changing."

Ebb and flow. Clean energy is, of course, a narrative that has been slowly developing in the United States over the past four decades or so, at least since President Jimmy Carter's administration. In the past, its visibility and its urgency have ebbed and flowed with the price of oil. Today, however, it's not just the wild fluctuation in oil prices that is driving the discussion. There is the economic crisis. There is the burgeoning climate crisis, with its implicit call for global cooperation. And there are fresh concerns about national security in an age of emboldened oil cartels and nuclear ambitions.

Addressing each of these priorities raises its own set of questions. At the moment, there is no consensus on how aggressively the United States should reduce greenhouse gas emissions over the few next decades or, more broadly still, the proper role of fossil fuels and renewable energy.

Meanwhile, almost every potential contributor to a " green energy economy"—wind and solar power, biofuels, nuclear power, energy efficiency—faces hurdles well beyond the technology of each system. Regulatory policies or economic issues stand in the way of massive, quick deployment of any of these.

And so, today, a new mentality is emerging among almost all the major energy players, from wind developers in the Dakotas to coal-plant operators in North Carolina: Energy issues can no longer be treated as piecemeal policy items left up to states and hodgepodge federal legislation to decide but instead must be addressed nationally, in a sweeping manner.

Want the country running on flex-fuel vehicles? "It's just a few hundred dollars more per vehicles," says retired Gen. Wesley Clark, the 2004 presidential candidate and now cochairman of Growth Energy, a group representing several of the nation's largest ethanol producers. "What would encourage an automobile manufacturer to believe he should do it would be a government policy that says we are moving in that direction."

Want more wind power? "The critical thing we are talking about here is national policy and the signals it sends to people," says Denise Bode, CEO of the American Wind Energy Association. "There is tremendous demand for wind power, but there is not enough transmission."

The idea that a nation should have a clear-cut national energy policy sounds obvious enough. In the United States, however, the truth is that energy has not always been considered a national issue, and in some ways it still isn't.

Nowhere is this more obvious than with the transmission grid, a sprawling jumble of wires and mechanical connections dating back 50, 80, even 100 years in some places. Today, the grid is divided into more than 140 "balancing areas" to help manage the distribution of power. But some are so localized that they can't communicate with their next-door neighbors. As a result, extra power in one region is often wasted rather than being sent to a place that needs it.

So if wind power, solar power, and plug-in electric vehicles are to be big players in the country's energy future, as many hope, this antiquated system for delivering electricity will have to change. The grid must be retooled, and new high-capacity power lines are needed to carry wind-generated electricity from the Midwest to the East and West coasts. To get those high-power lines approved, Bode and other advocates say, the federal government needs more authority to override nasty squabbles between states, environmentalists, and other interest groups that have typi-cally stalled such efforts. The federal government, the thinking goes, already has the authority to build natural gas pipelines across state lines, and electricity should be no different. That sentiment seems to be gaining ground even among regulators who once opposed it, although there are many issues still to be worked out. As Chu says, "If we just take the view that we are going to cram something down someone's throat, this is not a constructive way of doing business."

Infrastructure is only one part of the battle to make national energy problems a national issue. Another is technology. Even though wind power technology is relatively mature—it was the country's largest provider of clean electricity last year—most other renewable sources still need work. Improvements to photovoltaic cells could reduce solar power costs significantly. New drilling technologies could help geothermal spread across a larger geographic range. Advancements in biofuels, in particular to the enzymes needed to break down grasses and woods to produce ethanol, would have a major impact. Meanwhile, fossil fuels face their own technological challenges. If coal is to stay around for a while, it'll most likely be because of still-developing methods to capture carbon dioxide emissions before they enter the atmosphere.

Groundwork. Scientific breakthroughs don't come cheap. The economic stimulus package set aside $21.5 billion for scientific research, signaling that Washington is taking a much more active role in basic energy issues after years of declining budgets at national labs. But this is just the groundwork. The most powerful force to remake the energy America uses could be government policies: climate change legislation, which would set a price on carbon dioxide emissions, and a national renewable-electricity standard, which would require the United States to get a certain portion of its electricity from renewable energy. Both rules could have far-reaching impacts, forcing industries to massively reconsider their operations, giving financial investors confidence to pump money into wind farms, solar fields, and other industries, and convincing the coal industry that it's worth investing billions in technology to reduce emissions.

The consequences of climate change legislation, in fact, are expected to be so great that companies typically opposed to government regulation are asking Congress to go ahead and act just so that they can have some certainty about where to put their money.

What Washington won't do—not in theory, anyway—is pick specific winners. "The market will decide what the mix will be," says Matt Rogers, a former director at McKinsey & Co. and now one of Chu's top advisers. "It will be interesting to see what the market brings forward." Of course, in reality, Congress's record is one of subsidizing some industries but not others. Even within the biofuel world, corn-based ethanol is heavily supported, but some others, such as biofuel made from algae, receive almost no backing.

In this new era of national energy, one of the primary questions facing the country is that of timing. When should things happen? In what order? And how soon can they occur? "Broadly, what scares me is that we want to do this in an incremental fashion. We want this to come across as painlessly as possible," say Rich Wells, vice president of energy at Dow Chemical. "We need a breakthrough mentality."

It has become a cliché to say that there is no "silver bullet" for the nation's energy and climate problems. Most experts prefer to think about energy solutions as a collection of options to be deployed in tandem. Perhaps the most widely quoted example is the "wedge model," developed by Princeton University professors Stephen Pacala and Robert Socolow in 2004. It outlined 15 wedges, each one representing a way to significantly reduce greenhouse gas emissions over the next 50 years. Among them: raising the fuel economy of 2 billion cars from 30 mpg to 60 mpg and doubling nuclear capacity worldwide.

Only some of these, of course, are realistic in the shorter term. "If you're only going to do one, the top one is always energy efficiency," says Dow's Wells. "It is for the most part the easiest, cheapest fuel out there." Amory Lovins, chief scientist at the nonprofit Rocky Mountain Institute, agrees, saying that energy savings from highly fuel-efficient cars would be equivalent to "finding a Saudi Arabia under Detroit." Perhaps the biggest barrier for buildings has been the upfront cost of doing retrofits, with the need to convince people that the costs can be quickly recouped by lower energy bills. The stimulus package is taking a stab at this, setting aside $5 billion for home weatherization.