In the early days of this blog I remember writing about kite power, and a pioneering project to attach kites to the front of ships to help them save energy. That didn’t come to much. Then there was a buzz around a kite power company that Google bought and had… ahem, high hopes for. That disappeared too. There’s a third round of interest at the moment with the start-up KitePower. It’s an idea that won’t go away.
The reason why kite power remains an attractive idea is that wind speeds are higher at altitude. It isn’t possible to build a wind turbine tall enough to capture these higher speeds, and so kites or gliders with turbines attached are a potential solution. Kites are lightweight, cheap, and relatively easy to deploy. In theory, they should be easy to set up and start drawing free energy out of the sky.
The affordable nature of kites makes them a potential appropriate technology for developing countries, small island states and places without national grids. They’re need to be part of a wider ecosystem of renewable energy and storage, but they could be much more affordable and lower impact. You don’t need a huge amount of land, money or infrastructure to fly a kite.
If you’ve got a few minutes, the latest episode of DW’s Planet A series is all about kite power and is well worth catching up with:
The Earthbound Report 
I came across this some time ago, and it seemed an interesting approach: keeps the generating on the ground but no spooling in/out needed for generation, and readily scales up with networks of ‘kite turbines’.
https://www.windswept.energy
They seem to be making progress towards a viable product, I think