The higher you go in the atmosphere, there is less density and higher velocity, and therefore, stronger winds. It is for this reason that the weather forecast and wind speeds differ between the base and summit of a mountain.
It is also the reason why wind turbines are elevated 10m or more off the ground. As wind turbines get taller, there is an exponential increase in the amount of energy that can be captured.
Thus, it is no surprise that high altitude wind power is starting to be explored more thoroughly.
High altitude wind turbines are small airplane-like structures are flown between 250m and 600m in the air. Like a grounded wind turbine, these flying turbines have a spinning blade that generates energy driven by wind. A cord attached to the structure then carries the energy back down to earth.
High altitude winds are currently an untapped energy resource. In fact, a study published this past September in Nature Climate Change revealed that, in geophysical terms, the energy available in high altitude winds exceeds the world’s energy demand.
The study uses a theoretical climate model to predict that high altitude winds would be able to produce 1873 TW of energy and near surface winds could produce 428 TW. To put this in perspective, high altitude winds can generate enough energy to burn 1.873 trillion (that’s twelve zeroes!) 60W light bulbs burning for one hour.
These high altitude wind turbines could theoretically generate over 100x and 20x more energy than what is globally in demand, respectively.
This study is careful to point out that, though it is theoretically possible to rely only on energy created by high altitude winds, there would be obvious technical, economic and political limitations.
Although renewable energy markets showed growth in 2011, they still only fuel about 2.1% of the worlds energy use. Studies like this one give us no excuses as to why we are not putting more funding into research that will make theories become reality.
As Ken Calderia, one of the study’s co-authors, told National Geographic, "It's a resource that is large relative to human demand, and harvesting it has to do with economics and engineering, not fundamental limitations of the resource."