A system for generating energy from a current flowing in a body of water, the system comprising: a group of generator assemblies arranged with their axis parallel and substantially horizontal and rigidly connected to each other, each generator assembly comprising: a generally tubular housing including an open inlet end, an open outlet end and a flow passage extending through the housing between the inlet end and the outlet end; a generator comprising a plurality of impellors disposed within the central portion of the flow passage of the housing and configured to rotate a shaft extending longitudinally in the flow passage; and a plurality of stators extending across the flow passage, positioned on either side of the impellors and configured to return fluid flow into a straight through flow before water impacts the next impellor; a fixture assembly for securing the system at the bed of the body of water; a retaining means attaching the group of generator assemblies directly to the fixture assembly, the generator assemblies being held between the bed of the body of water and the surface of the body of water; the generator assemblies being operable to generate energy in response to the flow of the current; the group of generator assemblies being rotatable about a substantially vertical axis with respect to the fixture assembly; and wherein each generator assembly comprises an upstream orientation and the group of generator assemblies is configured to be free to rotate during generation of the energy to align the upstream orientation with the flow of the current. a group of generator assemblies arranged with their axis parallel and substantially horizontal and rigidly connected to each other, each generator assembly comprising: a generally tubular housing including an open inlet end, an open outlet end and a flow passage extending through the housing between the inlet end and the outlet end; a generator comprising a plurality of impellors disposed within the central portion of the flow passage of the housing and configured to rotate a shaft extending longitudinally in the flow passage; and a plurality of stators extending across the flow passage, positioned on either side of the impellors and configured to return fluid flow into a straight through flow before water impacts the next impellor; a generally tubular housing including an open inlet end, an open outlet end and a flow passage extending through the housing between the inlet end and the outlet end; a generator comprising a plurality of impellors disposed within the central portion of the flow passage of the housing and configured to rotate a shaft extending longitudinally in the flow passage; and a plurality of stators extending across the flow passage, positioned on either side of the impellors and configured to return fluid flow into a straight through flow before water impacts the next impellor; a fixture assembly for securing the system at the bed of the body of water; a retaining means attaching the group of generator assemblies directly to the fixture assembly, the generator assemblies being held between the bed of the body of water and the surface of the body of water; the generator assemblies being operable to generate energy in response to the flow of the current; the group of generator assemblies being rotatable about a substantially vertical axis with respect to the fixture assembly; and wherein each generator assembly comprises an upstream orientation and the group of generator assemblies is configured to be free to rotate during generation of the energy to align the upstream orientation with the flow of the current.