Ships have propellers which are designed to fling water relatively rearwards in an efficient manner. Tidal power is one area of ‘alternative energy’ which seems as if it has some chance for being cost effective.

My invention is therefore to combine this information and create a simple source of renewable energy.

Take ships which, due to economic conditions, are not currently being used and moor them securely in regions of high tidal flow activity.

Equip each with a generator, if they haven’t already got one on board. Disconnect the propeller shaft from the engine (using whatever clutch system is already being used). Then, allow the tidal movements to drive the props with the hull anchored in position (they might need to be partly driven up to speed to overcome inertia).

Store the energy extracted in batteries on board ship which can then be transported into dock, when fully charged, and connected to the grid.

This approach creates potentially large amounts of energy, using only surplus technology, in a very flexible way.