It's a bird, it's a plane, it's ... a floating wind turbine? As the United States gravitates to greener energy, one may be seeing more of these power-generating windmills that are suspended in the air.

The floating wind turbine operates without a tower. Some propel in the air, much like a helicopter — its tether sending electricity to the ground. A tether is the line of material that connects the air apparatus to the ground, much like the string on a kite. The windmills can reach as high as 15,000 to 30,000 feet (4,572 to 9,144 meters) in the air to capture high-speed jet streams of wind. While some of these flying machines are kite-like or suspended like a helicopter, others resemble floating reeds.

While private companies are racing to perfect the technology for floating wind turbines, the devices are not yet being used in the public sector. An ocean-based apparatus developed by StatoilHydro ASA has plans to launch in 2009 and would be the first to do so, according to the Associated Press. The British company Blue H also lays claim to an upcoming station.

Meanwhile, the Sky Windpower Corporation, which makes a helicopter-like device, says their product could be the cheapest way to harness energy yet. They tout their creations as fully capable of meeting the world's energy needs in a way that is Earth-friendly and doesn't call for a groundbreaking scientific discovery or expensive materials.

The secret to the floating wind turbine is the power of high-altitude winds. Because floating wind turbines reside at much higher altitudes than their non-floating counterparts, they can harness the energy of the same high-altitude winds that, for example, speed airplanes along. Through nuclear fission, a floating wind turbine made with strong but light material can harness that power through nuclear fission. Nuclear fission occurs when a massive nucleus of an atom is split into smaller nuclei, releasing energy in the process.

Global competition has emerged in the floating wind turbine field. Sky Windpower describes an energy that could cost less than $0.02 US Dollars (USD) a kilowatt hour.

Magenn, a Canadian company vying to perfect the floating wind turbine, has developed a "MARS" device that rotates horizontally, responding to the wind. Helium suspends MARS, and energy may either be used immediately upon being delivered to the ground, or it may be stored into a grid.

Opponents to this technology cite bad weather and competing aircraft in the sky as downfalls.