A system for generating power from a flow of liquid having at most thirty feet of head and a flow rate of at most 300 cubic feet per second, includes: an axial-flow turbine, a penstock, an intake, a generator, and a control circuit. Each blade of the turbine runner is releasably coupled to the hub and each blade: 1) is configured to extract energy from liquid flowing through the runner by rotating the hub when the flow of liquid contacts the blade, and 2) has a pitch that is adjustable. The length of the penstock is adjustable. The generator is operable to generate electric power from rotation of the turbine. The control circuit to determines changes in the flow of liquid and in response modifies at least one of the following: 1) the speed of the axial-flow turbine's hub, and 2) the flow of liquid that the runner receives.
