After turbines, kites?

Sunday, 28 February 2010

The turbine may be the icon of modern wind power generation for now but it could be replaced by the kite in most, if not all, wind generation applications sometime in the next couple of decades.

Turbines (for example) are, subject to engineering and economic constraints, mounted on the highest possible tower in order to capture faster/smoother winds (wind energy is proportional to the cube of the wind speed) but constructing a 70m+ tower, installing 60t+ of generator and control equipment on top of the tower and attaching 3x6t+ blades is extremely expensive and sometimes quite dangerous (installation can only be performed in low wind conditions at sites that are inevitably chosen for their consistently high winds). In addition, turbines can only operate within a certain minimum and maximum range of wind speeds (e.g. 4m/s to 25 m/s).

Modern airfoil kites coupled with specialised autopilot systems offer the real possibility of being able to tap higher, faster, more reliable winds at much lower installation costs (no tower, all heavy equipment at ground level) and comparable, or lower, maintenance costs, when compared to offshore wind farms (it seems likely that the kite control lines will need to be inspected and/or replaced on a fairly regular basis but this should be something that a man in a white van could do). Airfoil kites can also be flown in a way that offers the potential for them to operate across a much wider range of wind speeds.

Kite power generation has been an active area of research since, and almost certainly before, I first spotted it back in 2003/2004 and is now at the stage where a number of different groups have solved the all important autopilot problem:

Festo CyberKite: a German robotic solution to kite flying

Saul Griffith on kites as the future of renewable energy: warning, contains somewhat nauseating references to 'audacity' and Al Gore, the twat

SkySail: a working system to cut the fuel consumption of container ships

James May's Big Ideas: featuring a Dutch group working on kite power generation

The Dutch group are considering sending kites as high as 9..10km, into the jet stream which crosses the UK and Holland, where the winds are strong and consistent. This seems a bit far fetched because a system failure could leave 10km+ of high-tensile steel wire draped over a random segment of the countryside, with the resulting threat to life, limb, property and power lines that a vast, unruly, 10km wire saw would pose.

On the down side, robotic kite flying is an extremely challenging technical problem and such a system is actually very delicate in comparison to a conventional turbine generation systems. The failure of any kite generation system is likely to leave a kite its control lines (even if they are only synthetic fiber) draped across a large segment of the countryside.

Realistically, kite-based power generation systems, working at altitudes of 100..1000m, could be with us quite soon, generating much more power than a comparable turbine system, generating power more days of the year, in more varied wind conditions, at locations that were not previously seen as good sites for wind farms and for a much smaller initial investment.

Author: Black Hole Sunset

Reproduced from Jan. 2010

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Joe Public said:

	... Perhaps hundreds cound be used around airports, to make them carbon neutral??
	report abuse vote down vote up

February 28, 2010
Votes: +0

black hole sunset said:

...
Unfortunately, the immediate vicinity of an airport is probably the last place that a kite generator would be allowed to operate.

http://www.thekitesociety.org.uk/KiteRegs.htm

Article97 (3) (d)
A kite shall not be flown at a height of more than 30 metres above ground level within the aerodrome traffic zone of a notified aerodrome during the notified operating hours of that aerodrome. [Although it is generally accepted that for safety reasons you should not fly within 5km of any aerodrome].

There is also this:

Article 97 (3) (e)
A kite shall not be flown at a height of more than 60 metres above ground level.

For permission to exceed the limits stated above you are required to complete an application form.

If I had to guess, I'd say that 500m...1000m is the kind of height that would be required in order to make kites a worthwhile technology because this is sufficiently beyond the height of turbines in order to justify the additional complexity of a kite based generator.

Assuming they can be made to work in pracice, of course.