Kite Flying for Power
"A kite liberates the part of the wind turbine that generates the most power - the tip of the blade -
from the burden of the infrastructure, such as the hub, the tower and the gearboxes. The tip is so
efficient because it is moving fast, as a kite would, but whereas a turbine's blade turns heavy and
expensive gearing, the pull of the kite is used to spin a dynamo. Put simply, a kite takes the best bit of
a wind turbine and puts it where the wind is strongest.
At the height of the average wind turbine, 80 metres above ground, the wind typically blows at
around 4.6 metres per second. At 800 metres, this rises to 7.2 metres per second. The dependability of
the wind - how often it blows above certain speeds - also increases with altitude. It turns out that the
power available from wind is tied to the cube of its speed, so the higher of these altitudes is a far more
attractive option, giving you almost four times as much power as that available at turbine height. Go
up to 1 kilometre, and you can harness nearly eight times as much power (see Graph). All you need is
a kite - with a very long string."
"Kite Gen's electric winches will consume only about 12 per cent of the total generated power. The
difference between power generated and power used can be maximised by taking advantage of lulls in
the wind and also by using a mechanism that adjusts the kite's aerofoil in-flight to reduce lift, he says.
By repeating this cycle again and again, the kite acts as a wind turbine."
"The Delft researchers envisage a similar system that they call a "laddermill". Rather than a single kite,
they plan to stack kites on a single tether. These could change their tack or configuration depending on
whether they are being pulled out by the wind or reeled in by the winch. This way, they can maximise
lift as the tether unspools and reduce wind resistance as it is reeled in. The team says a full-size unit
could generate about 50 megawatts, almost 10 times the power generated by today's largest wind
turbines."
"When you can be so much cheaper than wind turbines and generate more power, there's going to be a
really big push for it," he says.
http://environment.newscientist.com/channel/earth/energy-fuels/mg19826562.000-to-make-the-most-
of-wind-power-go-fly-a-kite.html
Comment that no notice is made of the proposals to harvest wind in the jet stream. "The work of
http://www.skywindpower.com is most notable. Winds under 1000 meters have an entirely different
character than those above 15K meters. I would love to hear what the folks who have evaluated the
lower altitude concepts think of the high altitude proposals."
Next
Options Index
"A kite liberates the part of the wind turbine that generates the most power - the tip of the blade -
from the burden of the infrastructure, such as the hub, the tower and the gearboxes. The tip is so
efficient because it is moving fast, as a kite would, but whereas a turbine's blade turns heavy and
expensive gearing, the pull of the kite is used to spin a dynamo. Put simply, a kite takes the best bit of
a wind turbine and puts it where the wind is strongest.
At the height of the average wind turbine, 80 metres above ground, the wind typically blows at
around 4.6 metres per second. At 800 metres, this rises to 7.2 metres per second. The dependability of
the wind - how often it blows above certain speeds - also increases with altitude. It turns out that the
power available from wind is tied to the cube of its speed, so the higher of these altitudes is a far more
attractive option, giving you almost four times as much power as that available at turbine height. Go
up to 1 kilometre, and you can harness nearly eight times as much power (see Graph). All you need is
a kite - with a very long string."
"Kite Gen's electric winches will consume only about 12 per cent of the total generated power. The
difference between power generated and power used can be maximised by taking advantage of lulls in
the wind and also by using a mechanism that adjusts the kite's aerofoil in-flight to reduce lift, he says.
By repeating this cycle again and again, the kite acts as a wind turbine."
"The Delft researchers envisage a similar system that they call a "laddermill". Rather than a single kite,
they plan to stack kites on a single tether. These could change their tack or configuration depending on
whether they are being pulled out by the wind or reeled in by the winch. This way, they can maximise
lift as the tether unspools and reduce wind resistance as it is reeled in. The team says a full-size unit
could generate about 50 megawatts, almost 10 times the power generated by today's largest wind
turbines."
"When you can be so much cheaper than wind turbines and generate more power, there's going to be a
really big push for it," he says.
http://environment.newscientist.com/channel/earth/energy-fuels/mg19826562.000-to-make-the-most-
of-wind-power-go-fly-a-kite.html
Comment that no notice is made of the proposals to harvest wind in the jet stream. "The work of
http://www.skywindpower.com is most notable. Winds under 1000 meters have an entirely different
character than those above 15K meters. I would love to hear what the folks who have evaluated the
lower altitude concepts think of the high altitude proposals."
Next
Options Index
 | |  | |  | |  |