Today's news mentioned the insecure European gas supply. I had an idea of a solar powered robot used to extract hydrogen and oxygen from seawater. The amount of gas extracted would be very small, but a large number of simple robots would make this feasible. The robot would float on the surface, solar panels upward. electrodes on the outside would convert the water to hydrogen and oxygen, storing the gas in the body cavity. When full, the robot would use the three propellers on the outside to swim underwater and dock with a pipeline or mother robot to unload the gas. The light hydrogen might demand a heavy robot, perhaps a float on a cable could lead to the surface, making the up and down trips less energy intensive.
