In turbine operation, what is primarily driven through the stages?

In turbine operation, steam is primarily driven through the stages. Steam turbines harness the energy of high-pressure steam produced in a boiler. As the steam enters the turbine, it expands and moves through a series of stages, each consisting of blades fixed to a shaft.

The expansion of the steam causes the blades to rotate, which in turn converts thermal energy into mechanical energy. This mechanical energy can then be transmitted to generators to produce electricity or other machinery. The design of steam turbines enables efficient energy conversion, making them a dominant choice in many power generation applications.

The context of comparing steam to other fluids, such as water, oil, and gas, is important. While water can be used in hydro turbines to generate energy, and gas can be used in gas turbines, steam turbines specifically rely on steam as their driving medium. Oil is typically not used to drive turbines in a conventional sense, though it may be involved in lubrication or as a working fluid in specific types of engines. Hence, steam is indeed the correct answer, as it uniquely serves as the central working fluid in steam turbine operation.