Quotes of the Day

Pop quiz: what source of power doesn't come out of the ground, doesn't burn and isn't radioactive? Hint: it contributed the most new electricity generation to the U.S. grid in 2008.

The answer is wind power, the technology that has become synonymous with going green. Companies that started out small, like Denmark's Vestas and India's Suzlon Energy, have become multinational giants selling steel and fiberglass wind turbines; even blue chippers like General Electric have identified wind power as a major revenue source for the future, while the construction and installation of wind turbines will employ workers here in the U.S. Investing in wind power, said President Barack Obama at a turbine factory in Iowa on Earth Day, "is a win-win. It's good for the environment; it's great for the economy."

But for all the green talk and growth in wind power — it accounted for 42% of all new electricity generation added to the U.S. grid last year — wind still makes up less than 3% of America's total electricity generation. Even at current rates of growth, that figure is unlikely to change soon. The question is, Will wind ever produce enough power to satisfy America's energy needs?

A new study in the Proceedings of the National Academy of Science (PNAS) says yes. A team led by Michael McElroy at Harvard University assessed the global capacity for wind power — the total amount of sheer energy that's being carried on the breeze — and found that current technology could harness enough power to supply more than 40 times the planet's present-day levels of electricity consumption. For the U.S., there's enough wind concentrated in the Midwest prairie states to supply as much as 16 times the current American demand for electricity. The energy is there, on the breeze — it just needs to be tapped.

Wind-power estimates have been made before, but the PNAS team drilled them down to greater detail. Using a simulation of global wind fields from NASA's Goddard Earth Observing System Data Assimilation System — a network of complex computer systems used to simulate and predict meteorology — McElroy and his colleagues could map the distribution of wind resources around the globe, then calculate how much electricity could be produced by tapping those breezes with current turbines, which can generate about 2.5 megawatts on land, and larger turbines that can generate 3.6 megawatts offshore. (Offshore winds tend to be stronger and more constant than land breezes, hence they generate more power.)

The results show that there's more than enough wind to go around, and not just in breezy, big countries like the U.S. Even land-limited Japan can produce more than three times its current electricity consumption with wind power, provided it taps offshore wind. The problem isn't supply but distribution: in the U.S. and elsewhere, some of the richest wind resources tend to be far from the densely populated coastal areas that need the most electricity. Another problem is intermittency — even in Chicago, there are days when the wind doesn't below. But both those hurdles can be sidestepped by building a more modern and supercharged electrical grid, one capable of funneling wind-generated electricity from the middle of the country to the coasts. A dense and more connected network can also compensate for intermittency, with wind turbines in one part of the country backing up those in another.

So build the turbines, and the electricity will come? Not exactly. For one thing, offshore turbines would likely be necessary in a wind-centric energy future, but local communities in coastal areas have fought against offshore, claiming the turbines spoil seaside views. (One iconic project on Massachusetts' Cape Cod, called Cape Wind, has been tied up in legal challenges for eight years.) But the greatest obstacle is economic. Though the price of power from wind has dropped in recent years, it's still more expensive than most electricity from coal or natural gas. And while Obama the candidate wanted renewables to reach 25% of the U.S. energy mix by 2025, we're a long way from that goal (less than 3% of our power comes from non-hydro renewables), and there's growing doubt that even Obama's greener policies can bring us there. The cap-and-trade bill circulating in Congress contains a weak renewable-energy standard —just 20% of U.S. electricity would need to come from renewables by 2020, but that allows for nuclear power, and many utilities would be allowed to escape the requirement altogether. "We're off to a slow start," says Peter Duprey, CEO of Acciona Energy North America, which operates wind, solar and biofuel plants. "I'm disappointed with how things have gone [under Obama]."

Duprey and many others in the renewable-energy industry would prefer a feed-in tariff, which requires utilities to buy alternative electricity at above-market rates. Feed-in tariffs have already been used with considerable success in European countries like Spain and Germany, where renewable power has achieved greater penetration than in the U.S. But there seems to be little chance of that happening in Washington, in part because the nascent renewable-energy industry lacks lobbying might. "It's hard out there for us," says Duprey. "We're not as well organized as the coal or nuclear industry." Renewables like wind may have science on their side — but that may not matter until they can make their voice heard in Washington.

• Bryan Walsh
• A new study finds that we have the technology and wind power to supply more than 40 times the planet's current levels of electricity consumption. So what's the problem?