Yoyo (of which the recovery phase is not taken into account here) or flygen crosswind kites generate an irregular power during the figure-eight or the loop. The cyclic variations of the tether angle cause it.
About 14’ after the beginning we can see the whole loop and hear the sound variations that occur periodically on Makani’s video during each loop:
Then during figure-eight we can also hear athe sound variations:
The irregular power of FlygenKite prevents to load a laptop or a cell phone, unless implementing a sophisticated and expensive regulator.
So for small crosswind devices an irregular power can be a problem.
For large devices like Makani the quality of the produced electricty could be lower (adding irregular wind power by itself), unless implementing expensive temporary storage, or using very smart grid.
Are there some deeper studies of this concern?
A quick calculation show that the Makani 600 kW in a cycle of 22 seconds generates 3.7 kWh of energy. Even at $1000 per kWh storage, smoothing out these variations should not be an issue. We have to realize that Makani has a hitech approach already, and this is but a small niggle.
For reference, if the energy kite produced 50 kW on average throughout a year, at energy price $0.05, the kite produces roughly $22k of energy a year.
I am not sure even if this amount of smoothing is necessary. Makani are targeting utility scale wind production, and they will connect to solid infrastructure electrically wise. These variations will probably be absorbed by the grid. I’m no power electronics expert to state if that is possible for sure though.
Another point is, that if Makani could increase the tether length or turn tighter, the variation in elevation angle will be reduced. Remember Makani is still in the early stages, probably a lot of room for improvement if they eventually are able to enter the power market.
My short answer for the loop: no. For wind per hour of day - definitively, except AWE may fare better than windmills due to altitude options
