CCGTs: Flexible Facilities that Complement Renewable Energies and Contribute to the Stability of the Power Grid

A combined-cycle gas power plant is an electricity generation facility that uses two thermodynamic cycles to maximize energy efficiency. Firstly, natural gas is burnt in a gas turbine, which produces hot gases under high pressure. These gases turn the turbine, which generates electricity.

Instead of venting the exhaust gases, they are directed towards a heat recovery boiler. In the boiler, the heat from the exhaust gases is used to produce steam by heating up water. The steam produced is then sent to a steam turbine, which in turn generates electricity.

This dual process enables the energy contained in the natural gas to be used more efficiently, thereby reducing energy losses and increasing electricity production. Therefore, combined-cycle power plants deliver greater performance and create less pollution than traditional power plants.

Another upside is that CCGTs can be quickly started up and shut down, meaning that they are especially well suited to responding to variations in electricity demand. As such, they can help overcome the shortcomings with such intermittent renewable energy sources as wind and solar power.

The load factor is used to measure a power plant’s efficiency. It is defined as the ratio between actual electricity production over a given period and the maximum possible production level if the plant were operating at full capacity all the time. In other words, it indicates the proportion of time during which a power plant produces electricity compared with its maximum potential.

Not all power generation units operate at full capacity all the time. For renewables, the load factor provides an idea of their intermittency. It is not chosen, but imposed by weather conditions. For other generating facilities, such as CCGTs, the load factor is chosen or controlled according to whether it is economically viable to run the plant. That explains why it is important to use CCGTs to offset the intermittent nature of renewable generation.

For a number of years, we have been investing in CCGT projects to strengthen our integration across the electricity value chain. In Europe, we currently operate seven CCGTs and we are a partner in the West Burton plant.

In the United States, we acquired three gas-fired power plants in 2023, representing 1.5 GW of electricity generation capacity: Wolf Hollow I (745 MW), Colorado Bend I (530 MW combined cycle and 74 MW open cycle) and La Porte (150 MW open cycle).

With an installed capacity of 5.8 GW by the end of 2024, we are clearly on the right path to achieving our target of 7 to 10 GW of flexible electricity generation capacity by 2030.

Electricity is generated at TotalEnergies’ offshore oil and gas facilities by turbines that burn gas (fuel gas) extracted from the reservoir. We operate over 200 gas turbines, 85% of which are located offshore. Integrating CCGTs into our offshore platforms could improve energy efficiency by between 35% and 50%. However, rolling out this solution is a real challenge, since it runs into a number of size and weight constraints on offshore facilities. That is why we are investing in developing more compact and lighter combined cycles. Our R&D efforts in this area are focused on driving down the costs of new projects, simplifying the implementation of combined cycles at existing sites and thereby contributing to the wider deployment of combined cycles offshore.