An apparatus for use in generating electricity from a bidirectional water flow comprising a base structure; a primary flow pipe defining a first flow passage through the base structure; a secondary flow pipe defining a second flow passage through the base structure, wherein the first and second flow passages are configured for bidirectional flow; the primary flow pipe comprising: a convergent section; a mixing chamber, the convergent section being connected to a first end of the mixing chamber to define a venturi therebetween; and a diffuser section connected to a second end of the mixing chamber; the apparatus further comprising: an opening in the secondary flow pipe arranged to provide fluidic communication between the second flow passage and the mixing chamber; a turbine connectable to a generator and arranged to be rotated by water flow from the second flow passage; and, a control mechanism for directing the water flow from the second flow passage through the opening into the mixing chamber, where water flowing from a first direction flows into the mixing chamber from one end of the base structure and water flowing from a second direction flows into the mixing chamber from the opposite end of the base structure; and wherein the control mechanism can block the flow through the entire length of the second flow passage and can control the direction of the water so that all the water entering the primary and secondary flow pipes discharges via the primary flow pipe. a base structure; a primary flow pipe defining a first flow passage through the base structure; a secondary flow pipe defining a second flow passage through the base structure, wherein the first and second flow passages are configured for bidirectional flow; the primary flow pipe comprising: a convergent section; a mixing chamber, the convergent section being connected to a first end of the mixing chamber to define a venturi therebetween; and a diffuser section connected to a second end of the mixing chamber; the apparatus further comprising: an opening in the secondary flow pipe arranged to provide fluidic communication between the second flow passage and the mixing chamber; a turbine connectable to a generator and arranged to be rotated by water flow from the second flow passage; and, a control mechanism for directing the water flow from the second flow passage through the opening into the mixing chamber, where water flowing from a first direction flows into the mixing chamber from one end of the base structure and water flowing from a second direction flows into the mixing chamber from the opposite end of the base structure; and wherein the control mechanism can block the flow through the entire length of the second flow passage and can control the direction of the water so that all the water entering the primary and secondary flow pipes discharges via the primary flow pipe. a convergent section; a mixing chamber, the convergent section being connected to a first end of the mixing chamber to define a venturi therebetween; and a diffuser section connected to a second end of the mixing chamber; the apparatus further comprising: an opening in the secondary flow pipe arranged to provide fluidic communication between the second flow passage and the mixing chamber; a turbine connectable to a generator and arranged to be rotated by water flow from the second flow passage; and, a control mechanism for directing the water flow from the second flow passage through the opening into the mixing chamber, where water flowing from a first direction flows into the mixing chamber from one end of the base structure and water flowing from a second direction flows into the mixing chamber from the opposite end of the base structure; and wherein the control mechanism can block the flow through the entire length of the second flow passage and can control the direction of the water so that all the water entering the primary and secondary flow pipes discharges via the primary flow pipe. an opening in the secondary flow pipe arranged to provide fluidic communication between the second flow passage and the mixing chamber; a turbine connectable to a generator and arranged to be rotated by water flow from the second flow passage; and, a control mechanism for directing the water flow from the second flow passage through the opening into the mixing chamber, where water flowing from a first direction flows into the mixing chamber from one end of the base structure and water flowing from a second direction flows into the mixing chamber from the opposite end of the base structure; and wherein the control mechanism can block the flow through the entire length of the second flow passage and can control the direction of the water so that all the water entering the primary and secondary flow pipes discharges via the primary flow pipe.