Which characteristic makes a gas turbine a favorable prime mover?

• A. Its low power-to-weight ratio
• B. Its high thermal efficiency
• C. Its ability to rapidly start and carry full load
• D. Its low fuel consumption

Answer: (C)

The key idea is the ability to respond quickly and deliver full power. A gas turbine can go from idle to delivering rated shaft power in a short time because its rotating mass is relatively small and its combustion process can be raised to operating temperature and pressure rapidly. That means it can start up fast and maintain full-load operation reliably, which is highly desirable for a prime mover in applications like peaking power plants or grid stabilizing services.

This fast start-and-load capability is more defining than simply having high efficiency or low fuel consumption. While those traits are valuable, they don’t capture why a gas turbine is often chosen as a prime mover: the rapid ramping and solid full-load performance.