High-altitude wind power is making it possible to access the consistent wind currents at altitudes that are far beyond those that are accessible with standard tower based turbines. One of the device technologies that is building momentum is kite power developed by Nature Technology Systems and although this technology is largely untested in the commercial world, there is some interest in the potential it offers.
This is one of the Airborne Wind Energy (AWE) companies that have been springing up to take advantage of the winds that are to be found at higher altitudes. It is worth taking a closer look at each of the newer developments in the industry to get an idea of just how possible it is to produce wind power in ways other than the standard tower based turbines.
Nature Technology Systems (NTS) is a German company that has developed the crosswind system and is a wind power process that makes use of kites to harness the wind power. The NTS Principle is a patented method of generating energy from the wind and is unique in the efficient manner in which it works.
The principle under which NTS operates relies on a few principles:
- Energy output is cubed as the speed increases
- The greater the elevation the higher the wind speed
- The greater the elevation the more consistent the wind
- A kite can produce equal levels of wind energy as a conventional wind energy system with far greater efficiency
The difference between the NTS kites and a conventional wind turbine is that the NTS solution does not require huge amounts of building materials to create towers and turbines for implementation. Similarly it is not necessary to build extensive access roads to get to each device.
What is required in this case is an area of land that contains a closed length of rail track. This means there is still some environmental impact that will take place to build the rail and the other earth-bound components of the system. This is also where the bulk of the construction costs and maintenance are going to take place.
The Edge Provided By NTS Kites
An NTS kite is flown in constant figure eight patterns at significantly higher speeds than is possible with a conventional wind turbine. The nature of the kite means that it is able to withstand much higher wind pressure and can continue to operate whereas a tower-based turbine would be placed under tremendous stress.
By soaring up to 500m in altitude it is possible for the stronger and more consistent wind currents to be utilized. At this height it is possible to continue to generate energy without running into any safety problems.
The tethered kite pulls railed cars around a closed loop system. The kite is attached to the car by four thethers, two of which steer the kite and two to pull the car. The railed cars are connected by cables to the grid and electricity is passed straight in through the wheels.
The system devised by NTS is still a developing prototype with the effort proving the technology having been put into a 400 linear metre closed track using a 20 square metre surface area kite. As the company develops its model it plans to scale up the size of the kites with 40 square metre and 80 square metre surface area kites planned for the future. These kites will have far greater pulling capacity which translates into greater energy producing capabilities.
The numbers that have been displayed by the company in terms of the power generating capacity of the kites have indicated that a kite with a 10 square metre surface area is capable of producing 10 kW of electricity. It is still to be demonstrated how this will translate when it is scaled up, whether that is in terms of the size of the kites, the number of kites that run simultaneously on a track or the height at which the kites are deployed.
It is important to remember that the Airborne Wind Energy system that is still in development and the company is in the process of attracting investors to help fund it. There is still a great deal that has to happen before this particular use of kite power becomes a feasible source of wind power.
For more information about the various other prototypes nad developments in the AWE industry you can read our earlier article listed below.
Related article: High-Altitude Wind Energy Development