This story appears in the September 2009 issue of National Geographic magazine.
The sun is a utopian fuel: limitless, ubiquitous, and clean. Surely someday we'll give up on coal, oil, and gas—so hard on the climate, so unequally distributed worldwide—and go straight to the energy source that made fossil fuels. In a few sunny places where electric rates are high, like Italy and Hawaii, solar energy is already on the verge of being competitive. But in most places the sun remains by far the most expensive source of electric power—typically in the U.S. it costs several times more than natural gas or coal—which is why it still supplies only a fraction of a percent of our needs.
That won't change fast unless governments give solar a big boost. President Barack Obama campaigned with a pledge to institute a federal "renewable portfolio standard" requiring utilities to generate a quarter of their electricity from renewables by 2025. Yet even if Congress enacted that ambitious law, coal would still dominate the nation's electricity portfolio two decades from now, and solar energy would probably remain a minor contributor. Cap-and-trade legislation that sets a price on carbon emissions would not be a magic bullet for solar either. Both mandates would likely lead utilities to favor the cheapest renewables, like wind. Solar would make a sizable contribution only after 2025, once the expansion of wind energy had plateaued.
Some advocates say we need to encourage solar more directly. European nations have done so with "feed-in tariffs," laws that require electric utilities to pay premiums to solar-power producers, be they commercial power plants or private homes that pump energy to the grid. Such tariffs have made Germany and Spain solar leaders, creating a market that has helped drive down prices. The billions of dollars of tax credits and loan guarantees in the Obama stimulus package may have a similar effect.
Another option is for the federal government to invest directly in solar—for example, says Ken Zweibel of George Washington University, by funding the construction of giant solar plants in the desert Southwest, along with the high-efficiency transmission lines needed to carry the power nationwide. In Zweibel's version of the future, the sun would satisfy more than two-thirds of U.S. electricity needs by 2050, for an investment of about $400 billion. "Compared to what we just paid for the financial bailout, it's pocket change," he says.