Is the gas turbine more efficient than the large steam turbine?

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Multiple Choice

Is the gas turbine more efficient than the large steam turbine?

Efficiency differences between cycles drive this answer. A large steam turbine typically derives more useful work from the heat it receives because the Rankine cycle in big steam plants uses high boiler pressures and temperatures and can recycle heat more effectively, often giving a higher overall thermal efficiency in simple-cycle operation than a gas turbine (which runs a Brayton cycle). So, in a straightforward comparison, the gas turbine is not more efficient than a large steam turbine. If you hear about combined-cycle setups, the picture changes and a gas turbine in a combined cycle can approaches or exceed the efficiency of traditional steam plants. But the question compares a gas turbine with a large steam turbine, and the standard expectation is that the steam turbine plant is more efficient.

Efficiency differences between cycles drive this answer. A large steam turbine typically derives more useful work from the heat it receives because the Rankine cycle in big steam plants uses high boiler pressures and temperatures and can recycle heat more effectively, often giving a higher overall thermal efficiency in simple-cycle operation than a gas turbine (which runs a Brayton cycle). So, in a straightforward comparison, the gas turbine is not more efficient than a large steam turbine.

If you hear about combined-cycle setups, the picture changes and a gas turbine in a combined cycle can approaches or exceed the efficiency of traditional steam plants. But the question compares a gas turbine with a large steam turbine, and the standard expectation is that the steam turbine plant is more efficient.

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