[youeseh]

Kites are less predictable if there are lots and near each other. They require much more airspace. There's probably a balance between cost, size of kite, kite material, rope material and power generated compared to conventional wind mills.

[usrusr]

Yes, I believe that kites are very unlikely to ever compete with horizontal axis for things like large wind farms, even though projections claim that they could get more energy per square mile of wind energy park. But the current demonstration system is so small in terms of ground installation (basically truck-sized) that a horizontal axis turbine of similar site preparation would suffer a lot from the relative weakness of winds close to the ground, much worse than a full size turbine. If you happen to be in the market for a 100 kW turbine, chances are the 100 kW kite will be better in every single metric (apparently the kite is very low-wind capable). So much better actually that the kite might be very attractive to many who wouldn't be in the market for a small horizontal at all. Another market could perhaps be developed around an "upgrade kit" variant that's specifically designed for retrofitting to the base of existing (single-standing) horizontal turbine towers. The the rotor would always be upwind of the tower, the kite would always be downwind and they don't compete for wind because they harvest in entirely different air layers.

And who knows, perhaps once there is a few centuries of operation experience accumulated across sites, maybe it turns out that kite control actually is reliable enough to fly a dense park in formation. And unlike turbines that absolutely need to go big a kite park could go for number of units instead of size of units without suffering from weak ground winds which would enable much deeper utilization of mass manufacturing benefits. (Apparently they do have plans for larger units that fit the "1-7 MW" range of horizontals - if they get there and the technology remains practical it would be truly revolutionary)