In 1975, inspired by Patric Henretty’s water wheel (1899 patent), Gerald Erwin Steelman proposed to install a chain of parachutes that was able to collect water’s kinetic energy from a river or the sea. Unlike the flotation devices (lift) such as wind turbines or propellers, this system worked thanks to the drag force (drag) which is much more adapted to low speeds currents. Very suitable self-construction methods, this device can be installed on a sailing boat to reach power autonomy. The density of water makes it a concentrated source of energy (1000 times more than the equivalent at air speed). This resource is potentially much more stable over time than the wind or sun.
For further investigations, here are the original patents :
