STEPHANIE MARTIN: The last few years have been a time of record growth for the U.S. wind energy industry. The energy department says California had its best year ever last year -- adding more than 900 megawatts of wind-generating capacity throughout the state -- or enough to power 1 million homes.

Two new major studies out of Stanford University and Lawrence Livermore National Laboratory find there's much more wind power to be had. Enough, in fact, that wind could be the world's primary source of power.

Stanford University civil and environmental engineer Mark Jacobson authored one of those studies, which was released today. Professor Jacobson, why this surge in interest in wind power, especially when solar is becoming so cheap?

MARK JACOBSON: Well, I think if we look into the future at a large-scale clean, renewable energy future, we'll need to consider both wind and solar. The question has been: Is there enough wind power to provide huge amounts of energy given that it's actually relatively inexpensive compared to conventional fuels?

MARTIN: Your study concluded that wind could be used to meet the world's power demand several times over by the year 2030, assuming that wind turbines could be installed anywhere on the planet. So you're including land-based turbines like the ones Bay Area drivers might see driving over the Altamont Pass -- but there are other types you're envisioning as well. What are they?

JACOBSON: Well, we're envisioning mostly land-based turbines. However, there are companies that produce airborne wind energy devices, which are meant to fly and capture energy higher in the atmosphere. So there might be some of those going forward as well.

MARTIN: So, according to the 3-D computer modeling that you used in your study, what would a world running entirely on wind power look like?

JACOBSON: Well, first we actually suggest we run half the world on wind. To power half the world with wind we would need about 4 million large 5-megawatt wind turbines. Now, you might think that's a lot, but these turbines last about 30 years. And every year the world produces about 70 to 80 million automobiles. And 70 years ago, during World War II, the world produced -- in five to six years -- it produced about 800,000 aircraft. So it's not such a technical challenge to produce 4 million turbines to power the world. The areas required are not significant. Half of these would go over the water and half over land, and the land component would take up about 0.6 percent of the land area of the Earth. But all that area, almost 99.9 percent of it can be used for multiple purposes, such as agriculture, open space, farming and ranch land. So, it's not just used for wind.

MARTIN: We know that turbines can have many negative environmental impacts. They're loud. Their blades kill birds, and when we're talking about airborne turbines, there's the concern that they could interfere with commercial air traffic. How realistic is it really to think that such widespread use of wind power is possible?

JACOBSON: Well, it's great that you brought that up, because those are nice myths that are perpetuated. With regards to bird kills, wind turbines reduce bird kills, because natural gas, coal and oil all kill at the rate of 10 times higher per unit energy generated than does wind through air pollution, through land degradation and through buildings themselves.

MARTIN: If you could do a cost-benefit analysis of this for us, what would be the benefit and the cost?

JACOBSON: Well, by converting to wind and solar power in particular, you eliminate the health and environmental costs of fossil fuels, which are on the order of 3 percent of the gross domestic product of a given state, or the whole country. So, that's a significant cost saving that most people don't realize when they convert to solar and wind.

MARTIN: Mark Jacobson, thank you.

JACOBSON: Thank you very much Stephanie.

MARTIN: Mark Jacobson is a professor of civil and environmental engineering at Stanford University. His new study on wind power is published in the Proceedings of the National Academy of Sciences.

Read the Stanford wind power study here (PDF). Read the Lawrence Livermore release here.