Magenn helium balloon is an auto-rotating device (see also on Sharp rotor) using Magnus effect to add lift and stabilization, and comprising generators aloft. It is a stationary flygen AWES. The drag profiles (Savonius-like) arround the balloon make it both rotate and harness wind power.
The concerns are a low efficiency due to both drag profiles and a low swept area (only arround the balloon); the weight of the slow generators; the helium cost.
Omnidea helium balloon comprises a motor aloft to rotate it, and at a higher speed, increasing the Magnus effect. It is a yoyo system.