Thursday, 25 Sep, 2008 Technology

For many years people knew that wind can be used to generate energy, but no one was aware of the quantity of energy it could actually produce. In 2005 two scientists at Stanford University, Cristina Archer and Mark Jacobson, performed a detailed estimation based on already known models of air movement. However, they calculated the energy that could only be produced from winds blowing at an altitude of 80 meters. Their results showed that under perfect conditions the total energy would be around 72 trillion watts.

It is worth mentioning that last year the full electrical generating capacity of the U.S. was slightly above 1 trillion watts. Scientists came to a conclusion that this number is way below the potential. The speed of wind increases with the altitude. The power increases at the cube of wind speed, which means that the electrical generating capacity could reach at least 72 trillion watts. If a turbine blade was located a few miles up, it could produce up to 250 times the energy that the turbine generates on the ground.

Bryan Roberts, who works as an engineering professor at the University of Technology in Sydney, Australia, proposed an idea on generating energy from wind. His project is currently developed by Sky WindPower, an American company with headquarters in San-Diego. The project features kites with rotors that fly like a helicopter to altitudes of over a mile where winds are stronger. When the device arrives to the destination point in the sky, rotors switch to generating mode and transmit electricity down their tethers. In case the winds change their direction the flying electric generators (FEGs) follow them.

This project, which looks rather simple, is really not like anything that the energy infrastructure creates.

A team of scientists at Worcester Polytechnic Institute in Massachusetts worked on a similar project - inexpensive energy kites that fly on low altitudes. These kites are somewhat different from the FEGs because the do not carry generators into the sky and then send current down the string. Instead they move up and down several hundreds of feet in the air, producing pulses in the tether that provides power to the generator stored on the ground.

Source: Discover Magazine