A flow controller configured to selectively act as a pump or as a flow regulator for a transport of fluid from a first reservoir to a second reservoir, the flow controller comprising: an inlet connectable to the first reservoir; an outlet connectable to the second reservoir; a pump assembly arranged between the inlet and the outlet, the pump assembly comprising a pumping wheel configured to pump fluid through the flow controller in a flow direction from the inlet to the outlet, thereby pumping fluid from the first reservoir to the second reservoir; a flow regulator assembly arranged between the inlet and the outlet and configured to allow fluid to flow through the flow controller in a flow direction from the inlet to the outlet thereby allowing the fluid to flow from the first reservoir to the second reservoir, the flow regulator assembly is configured to be selectively set in an electricity generating mode or in a flow decreasing mode, the flow regulator assembly comprising a turbine wheel, in the electricity generating mode the turbine wheel is configured to be turned by a flow of fluid flowing through the flow controller to provide hydro electrical generation, in the flow decreasing mode the turbine wheel is configured to rotate against the flow direction from the inlet to the outlet, thereby regulating a fluid flow from the first reservoir to the second reservoir; and a mode controller configured to selectively set the flow controller in a pumping mode, in the electricity generating mode, or in the flow decreasing mode, wherein in the pumping mode the flow regulator is acting as a pump, in the electricity generating mode the flow regulator is acting as a flow regulator and at the same time as a generator for electricity, and in the flow decreasing mode the flow regulator is acting as a flow regulator and at the same time slowing down the flow of fluid through the flow controller, wherein the pumping wheel of the pump assembly and the turbine wheel of the flow regulator assembly is a common wheel, wherein upon the flow controller being set in the pump mode the common wheel is configured to pump fluid through the flow controller in the flow direction from the inlet to the outlet thereby pumping fluid from the first reservoir to the second reservoir, wherein upon the flow controller being set in the electricity generating mode the common wheel is configured being turned by the flow of fluid flowing through the flow controller in the flow direction from the inlet to the outlet thereby provide hydro electrical generation, and wherein upon the flow controller being set in the flow regulating mode the common wheel is configured to rotate against the flow direction from the inlet to the outlet thereby regulating a fluid flow from the first reservoir to the second reservoir. an inlet connectable to the first reservoir; an outlet connectable to the second reservoir; a pump assembly arranged between the inlet and the outlet, the pump assembly comprising a pumping wheel configured to pump fluid through the flow controller in a flow direction from the inlet to the outlet, thereby pumping fluid from the first reservoir to the second reservoir; a flow regulator assembly arranged between the inlet and the outlet and configured to allow fluid to flow through the flow controller in a flow direction from the inlet to the outlet thereby allowing the fluid to flow from the first reservoir to the second reservoir, the flow regulator assembly is configured to be selectively set in an electricity generating mode or in a flow decreasing mode, the flow regulator assembly comprising a turbine wheel, in the electricity generating mode the turbine wheel is configured to be turned by a flow of fluid flowing through the flow controller to provide hydro electrical generation, in the flow decreasing mode the turbine wheel is configured to rotate against the flow direction from the inlet to the outlet, thereby regulating a fluid flow from the first reservoir to the second reservoir; and a mode controller configured to selectively set the flow controller in a pumping mode, in the electricity generating mode, or in the flow decreasing mode, wherein in the pumping mode the flow regulator is acting as a pump, in the electricity generating mode the flow regulator is acting as a flow regulator and at the same time as a generator for electricity, and in the flow decreasing mode the flow regulator is acting as a flow regulator and at the same time slowing down the flow of fluid through the flow controller, wherein the pumping wheel of the pump assembly and the turbine wheel of the flow regulator assembly is a common wheel, wherein upon the flow controller being set in the pump mode the common wheel is configured to pump fluid through the flow controller in the flow direction from the inlet to the outlet thereby pumping fluid from the first reservoir to the second reservoir, wherein upon the flow controller being set in the electricity generating mode the common wheel is configured being turned by the flow of fluid flowing through the flow controller in the flow direction from the inlet to the outlet thereby provide hydro electrical generation, and wherein upon the flow controller being set in the flow regulating mode the common wheel is configured to rotate against the flow direction from the inlet to the outlet thereby regulating a fluid flow from the first reservoir to the second reservoir.