What is the benefit of using a 'combined cycle' power plant?

A combined cycle power plant is designed to enhance overall thermal efficiency by integrating both gas and steam turbines in its operation. In this system, gas turbines generate electricity by burning fuel, and the hot exhaust gases produced during this process heat water in a heat recovery steam generator. This steam then drives a steam turbine, creating additional electricity.

This dual approach allows the plant to use the energy content of the fuel more effectively compared to a simple cycle power plant that utilizes only one type of turbine. As a result, combined cycle plants can achieve thermal efficiencies of around 60% or more, significantly higher than traditional power generation methods. This high efficiency not only maximizes the energy output from the same amount of fuel but also reduces greenhouse gas emissions per unit of electricity generated, making it an environmentally favorable solution for power generation.

Understanding the combined cycle process showcases the importance of utilizing both gas and steam turbines to make power generation more efficient and effective, which is why this answer is the correct choice.