One cold evening in February 2008, the gusty wind in West Texas dropped to a breeze. At the time, Texas generated more electricity from wind than almost any other state did. But that evening, the wind speed fell much lower than forecasts had predicted, just as the chill had residents cranking up their heat. The people responsible for most of the state’s electrical system recognized that they risked a dangerous—or at least embarrassing—outage. Declaring an emergency, they switched off the power to several big industrial customers. After 90 minutes, backup generators kicked in, and the power was restored. A spokeswoman for the Electric Reliability Council of Texas subsequently explained, “The wind died out. That happens.”

Well, sure, some critics agreed—but that was just the problem with relying on it. The same, more or less, was true of sunlight. Weather didn’t follow orders, and its patterns could be unpredictable. With the state planning to dramatically expand its use of wind power, one journalist wrote: “This problem is only going to get bigger for Texas.”

Eight years on, the problem is getting bigger for the United States. Last August, President Obama announced the Clean Power Plan, whereby power plants are expected to reduce their carbon-dioxide emissions by 32 percent from their 2005 level, within 15 years—a target that’s all but impossible to hit without moving from coal to cleaner energy sources. The Supreme Court has stayed Obama’s plan until lower courts can rule on several legal challenges, but energy experts assume the plan—or something like it—will eventually take effect. In the future, environmental concerns and resulting regulations may necessitate bigger reductions; Bill Gates argues that, in order to really address the global-warming crisis, emissions must fall by 100 percent before too long.

That makes the question of reliability more urgent than ever. Because wind and sunlight are fickle, utilities have used dirtier backup sources like coal and natural gas. If we want to eventually get all our energy—or a large majority of it—from renewable sources, something has to change. As Gates told the The Atlantic in November, “We need an energy miracle.” Gates is investing billions of dollars in schemes that sound like they’re out of an Isaac Asimov novel: batteries the size of swimming pools to store renewable power, technologies that use sunlight to produce liquid fuel.

But over the past couple of years, researchers have come across another potential solution, one that seems almost too simple. The wind is usually blowing somewhere, and the sun is usually shining somewhere. If we could just connect the whole country to a special grid that would let utilities tap into those resources anytime, wouldn’t that get rid of—or at least lessen—the reliability problem?

The most recent high-profile paper making this argument was published in January by researchers at the National Oceanic and Atmospheric Administration and the University of Colorado at Boulder. Christopher Clack and colleagues built a model to predict the long-term costs of putting all kinds of energy into the electrical system. When they imposed a constraint on their model—it couldn’t use coal—they found that the cheapest option involved a grid of transmission lines that could carry solar and wind energy from almost any part of the country to anywhere else. Other technologies—perhaps Gates’s imagined miracle—would still be required to get rid of carbon-emitting fuels altogether, but the new grid would get us quite far, reducing emissions from power plants by up to 80 percent within 15 years.

This conclusion, Clack said, appeared to surprise some energy researchers. Sending wind or solar energy long distances inevitably involves the loss of some power during transmission, and the alternating-current, or AC, lines that connect most of the U.S. are less efficient for long-distance transmission than direct-current, or DC, lines. The paper’s hypothetical grid would use DC instead of AC. Until recently, big investments in high-voltage DC lines have been rare, in part due to the cost of the technology required at substations to make the power usable. But the model found that if you built a nationwide grid, economies of scale would emerge. In short, the benefits of having long, efficient lines outweigh the cost of power conversion. “People assumed that storage was the key or that nuclear was the key—and now I think there’s more of a recognition that you can actually get quite a long way today,” Clack said, just by changing how renewable energy moves around.

This hypothetical grid recalls the interstate highway system championed by President Dwight D. Eisenhower in the 1950s. Back then, the U.S. was connected haphazardly with narrow roads built by state and local governments. Eisenhower predicted that cars would soon become ubiquitous, so he signed a law authorizing funds for an ambitious expansion of the nation’s highways—an approach that turned out to be prescient. Clack’s vision seems similar. So why don’t we invest in a new grid for power transmission, like Eisenhower did for car travel?

The answer reveals a lot about how the U.S. has changed since Eisenhower’s time, politically and otherwise. The creation of a grid like Clack’s would most plausibly result from federal legislation. The Department of Energy would likely be tasked with studying how the grid might be built, and the Federal Energy Regulatory Commission with deciding where to put the lines. A bidding process would probably ensue, with developers vying to build portions of the grid, whose cost they’d expect to recoup, likely by charging utilities a fee, which the utilities would in turn pass on to their customers.

It’s not hard to see the challenges emerge, one by one, when you consider this scenario. The current Republican-led Congress has evinced little interest in big infrastructure projects. The lines might be opposed in states whose economies (and politicians) depend on coal and natural-gas companies—and even those states that support renewable power tend to favor its production within their own borders. Local utilities resist being told what to do by the federal government.

But suppose for a minute that the government and the utilities found a way to agree that a national grid should be built. Even then, developers would face opposition from landowners who wouldn’t want their property bisected or their views obstructed by unsightly power lines. Anjan Bose, an expert in the engineering of power systems who teaches at Washington State University and has advised the Department of Energy, notes that China and India, whose government systems are oriented around central planning, are doing something like what Clack is promoting—but he sees it as impossible in the U.S. When he heard about Clack’s research, he told me, “my first reaction was ‘Good luck.’ ”

Politics and nimbyism aside, there’s another difference between the U.S. and those Asian countries: Energy demand in India and China is rising with industrialization—but the U.S. is losing factories, not gaining them, and energy demand is expected to be nearly flat for years to come. China and India need more transmission lines, but in the U.S.—where the argument for new lines is largely environmental—the case is tougher to make. Of course, meeting federal and state regulations will require utilities to use more renewable power, but people seem to be hoping that other technologies, requiring less funding from utilities and their customers, will get us there.

Some experts suggest that, given the difficulties of coming up with a national plan, jury-rigging a piecemeal system might be a better bet—old, worn-out transmission lines, including AC lines, could be upgraded, and a few strategic regional DC lines could be built. But even that would be difficult to do. Clean Line Energy Partners, a developer in Houston, has been laboring for years to build four interstate DC lines. But these projects have moved slowly—in part due to local opposition. Comparing this patchwork approach with Clack’s vision, Michael Skelly, the president of Clean Line, told me, “I think a national grid would be far better.” He feels that with the federal government’s weight behind a national plan, companies like his might encounter less local opposition—or could at least better appeal to federal authorities to help them fight it.

And so the search for a miracle continues. In Tallahassee, Florida, the manager of integrated planning for the city’s electric system, David Byrne, told me that for decades his city has relied almost entirely on natural gas. But the expected emission regulations and demand from residents recently persuaded Byrne and his colleagues to invest in renewable sources. They’re now building a solar farm, Tallahassee’s first, on the municipal airport’s land. That will produce only about 2 percent of the city’s energy, though—and Byrne expects that it could be tough to find land cheap enough to meaningfully increase that figure using sunshine alone. So Byrne is looking for wind, too. The problem is that in Florida, there just isn’t much of it. Some time ago, Tallahassee signed a memorandum of understanding with Clean Line to transmit wind power from rural Oklahoma. That line just received important support from the Department of Energy, but it still has to overcome some hurdles before Clean Line can break ground.

“The energy resources that we would like to have seem to be located in places where people really don’t live,” Byrne pointed out. As long as private, regional projects keep getting stymied—and as long as Clack’s vision for a national system remains hypothetical—that will continue to be true.