Using kites and balloons to tap the strong, consistent winds more than two kilometres in the air could avoid many of the pitfalls of more down-to-earth wind farms, according to the first market report on the nascent industry by consultancy GL Garrad Hassan.
No commercial scale pilots have been tested in the air yet, according to the report, but small-scale prototypes have been tried out. ‘Real scale’ prototypes are being developed by some of the 22 companies active in the high altitude wind energy (Hawe) field.
At greater altitudes, wind velocity is higher and more consistent than at ground level. Hawe systems vary in design but may involve a kite, parachute, rotating balloon or fixed wing, tethered to the ground or an offshore platform.
For example, California-based Makani Power has received a $15 million grant from Google to build a prototype of its ‘wing concept’, which has an onboard computer that navigates the wind in a circular pattern mimicking a traditional wind turbine, the report says. The company plans to have products on the market in 2013-14, with a 1MW model on sale in 2015.
Germany's SkySail Power has invested €50 million ($72 million) in its kite technology, according to the report, which is also attaches to commercial ships to generate power.
Italian firm KiteGen Stem uses a pulley system to generate electricity, and has already tested a prototype at 800m. The report says the firm is testing a 3MW capacity system. Other firms are closer to the drawing board.
Onshore wind farms are currently the most popular renewable energy projects but, the report predicts, Hawe systems could help meet growing demand for carbon neutral electricity generation without taking up space on land.
Oceans too deep to install traditional offshore wind turbines could host floating tethers for Hawe systems, the report predicts. West of the UK and Ireland, east of Japan, the Pacific west of Oregon and British Columbia are all “promising areas” for such developments.
Nascent industry focusing attention 2km up and higher
These systems fly more than 200m up, with most of the industry’s attention focused on harnessing winds more than 2km up. Hawe systems could operate at heights of up to 20km, the report predicts.
China is expected to lead the Hawe market, also known as the airborne wind energy industry, as in the wider clean energy space. But in Europe, the UK will dominate, Garrad Hassan predicts.
More research is needed to fill in gaps in the data about wind speeds so far above ground, says the report. Further technical developments will also be needed, such as to deal with the threat of thunder and lightening, the weight of tether cables that can transmit electricity and control of the systems.
Winning permission from air traffic authorities will also be a hurdle, the report acknowledges. “Considering the experience of commercial wind developments in respect of flight path issues and radar interference, the authorities are likely to be very conservative and restrictive in their responses to flight path issues,” the report warns.
By. Jess McCabe