The U.S. Department of Energy has just released new estimates of the nation's wind energy potential. It's three times what the agency had estimated before.

Now, the department says the nation -- not counting Hawaii and Alaska -- could produce 37 million gigawatt hours of wind power annually. That nearly ten times the total power generated in the U.S. in 2009, which was four million gigawatt hours.

A word of caution: These studies of "wind potential" often are based on what you could generate if you put wind turbines on every realistic spot available, which is unlikely.

There's also still the question of reliability. Since the power grid has no storage, power has to be produced when it is needed, and the wind doesn't always blow.

And, yes, the question of how to get the power from where the wind is blowing to where it is needed. The central plains are often called the nation's Saudi Arabia of wind, but most of the power demand is far, far away on the East Coast.  That's why offshore wind has been such a tempting technology along the East Coast. New Jersey is moving forward with three offshore projects.

But what's notable about the current study, carried out by the National Renewable Energy Laboratory and AWS Truewind, is that the estimates are based on current wind technology, which is advancing all the time.  Who knows when the estimate may triple yet again.

A press release from the DOE continues: "Along with the state-by-state estimates of wind energy potential, NREL and AWS Truewind have developed wind resource maps for the United States and for the contiguous 48 states that show the predicted average wind speeds at an 80-meter height." (Most of Pennsylvania and New Jersey score in the lower sector.) 

"The new estimates reflect substantial advances in wind turbine technology that have occurred since DOE's last national wind resource assessments were conducted in 1993. For example, previous wind resource maps showed predicted average wind speeds at a height of 50 meters, which was the height of most wind turbine towers at the time. The new maps show predicted average wind speeds at an 80-meter height, the height of today's turbines. Because wind speed generally increases with height, turbines built on taller towers can capture more energy and generate more electricity. The new estimates also incorporate updated capacity factors, reflecting improvements in wind turbine design and performance."