Embodiments are directed to an expander having two or more hydraulic stages with different physical geometries. In an embodiment, a first hydraulic stage uses nozzle vanes machined with a first geometry, while a second hydraulic stage uses nozzle vanes machined with a second geometry. Different nozzle vanes can be combined to tune the performance of the expander as the optimal operating conditions change. In yet another embodiment, an expander is equipped with a generator having a double wound stator with two sets of parallel windings. For high operating loads greater than a threshold, a first set of windings operates while a second set of windings, operating at a lower frequency, is disconnected. For operating loads that are less than the threshold, the first set of windings is disconnected and the second set of windings operates, enabling the generator to continue to operate close to 100% load for less expander power.