The present invention refers to a linear electric generator, comprising: at least one intake port; at least one expansion chamber, and at least one expansion piston; at least one central cylinder; at least two reduced cylinders, wherein the diameter of said reduced cylinders is smaller than the diameter of the central cylinder, and wherein each reduced cylinder comprises a partition; at least one electric power-generating set of pistons, wherein each piston of said set of pistons is located inside the central cylinder and is suitable to linearly move inside the inner void of a reduced cylinders through the partitions of the reduced cylinders, and wherein each said piston is connected to an oscillator; at least one fluid chamber suitable to comprise incompressible fluid, wherein said fluid chamber is the void between the edge of the expansion piston closer to the electric power-generating pistons and the electric power-generating pistons themselves; at least two sets of magnets, wherein each set of magnets is attached to an oscillator; at least two end sections that comprise coil windings; and at least one outlet port, suitable to allow the evacuation of fluids from said expansion chamber. The invention also refers to a method for energy transformation.