Cell for converting fluid-dynamic forces into electrical energy, characterised in that it comprises: - a support body crossed by a channel which opens with an inlet onto the face of said body which is exposed to the incident action of the fluid-dynamic force and which with the opposite inlet opens into a cavity inside said body, so that said force crosses said channel from its front inlet towards said cavity; - at least one piezoelectric generator supported by an own body, positioned in said cavity and oriented with its front armature perpendicularly and coaxially to said channel, so that said fluid-dynamic force has an incident action on the centre of said front armature; - a valve positioned in said channel to cyclically close it and open it, having a sleeve shape, with long annular portion such as to be fixed externally in said channel with its proximal end and reach with its distal end said cavity and in contact with said front armature of the piezoelectric generator; said valve forms with its inner walls a sphincter channel which with its proximal portion is exposed to the action of the fluid-dynamic force and which in an intermediate area is initially closed; said valve being made of non-Newtonian polymer materials, of pseudoplastic type, and such that at the beginning of each transformation cycle, the inner channel of said valve is normally closed and the same valve transmits to the piezoelectric generator the thrust which it receives from the fluid-dynamic force so that said generator begins to charge itself; when the shear strain acting on the inner channel of the pseudoplastic valve exceeds the permitted design load, said inner channel of the pseudoplastic valve modifies its inner shape and opens, so that the action of the fluid-dynamic force is manifested directly and with greater intensity in the area of contact between the distal end of the valve and the piezoelectric generator; the latter is further charged until also the distal end of the pseudoplastic valve, under the effect of the pressure, modifies its state and opens, leaving the fluid-dynamic force free to flow through discharge channels; - discharge channels located on the outside of said cavity, which open onto the rear face of the body of the cell, normally closed by the distal end of the pseudoplastic valve and by the contact of the latter on the front armature of the piezoelectric generator and arranged so that when they are opened by the change of state (8") of said distal end of the valve, they cause a sudden pressure drop upstream, both on the piezoelectric generator which releases the electric charges produced in the previous compression phase, and in the axial channel of the pseudoplastic valve which re-acquires its initial shape and closes to start a new conversion cycle of the type described. - a support body crossed by a channel which opens with an inlet onto the face of said body which is exposed to the incident action of the fluid-dynamic force and which with the opposite inlet opens into a cavity inside said body, so that said force crosses said channel from its front inlet towards said cavity; - at least one piezoelectric generator supported by an own body, positioned in said cavity and oriented with its front armature perpendicularly and coaxially to said channel, so that said fluid-dynamic force has an incident action on the centre of said front armature; - a valve positioned in said channel to cyclically close it and open it, having a sleeve shape, with long annular portion such as to be fixed externally in said channel with its proximal end and reach with its distal end said cavity and in contact with said front armature of the piezoelectric generator; said valve forms with its inner walls a sphincter channel which with its proximal portion is exposed to the action of the fluid-dynamic force and which in an intermediate area is initially closed; said valve being made of non-Newtonian polymer materials, of pseudoplastic type, and such that at the beginning of each transformation cycle, the inner channel of said valve is normally closed and the same valve transmits to the piezoelectric generator the thrust which it receives from the fluid-dynamic force so that said generator begins to charge itself; when the shear strain acting on the inner channel of the pseudoplastic valve exceeds the permitted design load, said inner channel of the pseudoplastic valve modifies its inner shape and opens, so that the action of the fluid-dynamic force is manifested directly and with greater intensity in the area of contact between the distal end of the valve and the piezoelectric generator; the latter is further charged until also the distal end of the pseudoplastic valve, under the effect of the pressure, modifies its state and opens, leaving the fluid-dynamic force free to flow through discharge channels; - discharge channels located on the outside of said cavity, which open onto the rear face of the body of the cell, normally closed by the distal end of the pseudoplastic valve and by the contact of the latter on the front armature of the piezoelectric generator and arranged so that when they are opened by the change of state (8") of said distal end of the valve, they cause a sudden pressure drop upstream, both on the piezoelectric generator which releases the electric charges produced in the previous compression phase, and in the axial channel of the pseudoplastic valve which re-acquires its initial shape and closes to start a new conversion cycle of the type described.