In the United States, the boom in wind energy has been dramatic. Last year wind generation grew more than all other sources of energy in the United States — and supplied almost five percent of total demand for electricity. And no wonder, as the cost of wind technology has plummeted 58 percent over the last five years, according to the American Wind Energy Association.
If a new report from the Department of Energy is correct, the potential for wind to generate energy in the United States is far, far greater. At the same time, though, it’s also greatly limited by a key factor — most of the wind turbines being used in the country today aren’t tall enough. If they were extended higher, where winds tend to be stronger and also more constant, they could potentially not only tap more energy — they could tap it in vastly more places.
Or as the DOE put it:
The deployment of taller wind turbines (already prevalent in Germany with average hub heights at 116 m) will expand U.S. land area available for wind deployment by 54%. Further innovation and increasing heights to 140 m will increase that further to 67%. Innovations addressing the technical and economic challenges, as well as the environmental and human use considerations, are critical to realize the nation’s full wind power potential and value for all 50 states as described in this report.
Taller turbines, the report said, will be critical to an outlined DOE vision in which wind comes to supply 20 percent of all U.S. power by the year 2030, and then, 35 percent by the year 2050. For the 2030 vision to be realized, wind power must be expanded to 49 out of 50 U.S. states — not all of which have lower-level winds that are strong or reliable enough to be tapped with the technologies most commonly used now.
Because of friction, wind generally blows with less energy lower to the ground than it does as you ascend into the atmosphere. Thus, the key trick for expanding wind power to new areas is to build turbines tall enough and also strong enough to capture wind energy at greater altitudes. According to the American Wind Energy Association (AWEA), a height of 80 meters for wind turbines has been the “state of the art for multiple years,” but there are already some thousand wind turbines in the United States that are taller than 100 meters.
But they need to get taller still. At wind hub heights of 110 meters, an additional 4,262,000 square kilometers of area in the United States would become technically suitable for turbines, and with heights of 140 meters, an additional 4,629,000 square kilometers would be available, according to the DOE report. (Currently, with heights of 80 meters, only 2.8 million square kilometers were technically available as of 2013.)
“Regions primarily affected by this increased technical potential include the Southeast, states bordering the Ohio River Valley, the Great Lakes Region, the Northeast, and portions of the Interior West and Pacific Northwest,” according to the study.
The new research suggests there’s nothing fundamentally blocking these innovations on a technological level. “We’ve proven out as an industry in Europe, with a fair number of turbines in Europe at 120 meters,” said Tom Kiernan, the chief executive of AWEA. “So it’s tested out in Europe, we think we can deploy it here in the U.S., and it’s an exciting evolution for the industry.”
Still, building turbines taller will present a lot of hurdles. They will require more material to construct and stronger structural supports and foundations, all of which costs more. And those parts will be more expensive and difficult to transport and to install. For anybody who’s seen parts from a gigantic wind turbine getting driven along the highway on a truck bed, just imagine something even bigger.
“Larger turbine components require special transportation and support vehicles and can only be transported on certain U.S. highways,” noted the DOE.
Finally, there are also nontechnical concerns: potentially more threats to birds and bats, and the fact that people might resist gigantic turbines in some places. Nonetheless, the DOE — and the wind industry — hopes such challenges can all be overcome.
“By going to 100 or 110 meters, we can open up all 50 states,” Kiernan said.
Also in Energy & Environment: