Makani (Acquired by Google and shut down) built large airplane/kites which transmitted wind power to the ground via a tether. The engineering challenges were...

Makani (Acquired by Google and shut down) built large airplane/kites which transmitted wind power to the ground via a tether. The engineering challenges were... intense. This was all documented extensively and this documentary summarizes all the footage they took: https://www.youtube.com/watch?v=qd_hEja6bzE https://www.youtube.com/watch?v=qd_hEja6bzE One of my favorite engineering projects and documentaries, just because of the sheer ambition and scale, and the grit of the team to keep pushing through repeated failures. Sad the project was cancelled but it makes sense given the cost and complexity.