Combined Cycle Gas Turbine (CCGT)
The energy mix of electricity production
There are three main sources for electricity production in France:
Nuclear production, with energy recovery from the fission reaction in reactors equipped with steam boilers supplying steam turbines connected to generators;
Thermal generation, where electricity is generated from the energy produced by burning fossil fuels such as fuel oil, coal and natural gas. In a more modest proportion, thermal electricity production can be carried out from biomass (wood, straw, agricultural residues) or on a decentralised basis by cogeneration units with steam recovery (heating of industrial processes and heat networks) co-produced with electricity;
Renewable production from intermittent energy sources such as hydro, wind, solar and bioenergy. Hydropower is one of the main sources of renewable energy for electricity production. It is produced from dams where the gravitational energy of the water is transformed into electricity in turbo-generators.
Distribution of electricity generation by sector
(source: 2021 RTE Electric Balance Sheet)
Electricity production capacities
In France, in 2021, the electrical power of the entire production fleet is of 139.1 GW, i.e. an increase of 2% compared to 2020. This slight increase is based in particular on the solar sector, which has undergone an increase of +26% over the year.
French fleet installed in 2021
(Source: RTE 2021 electricity report)
Electricity consumption in France, by
Compared to 2020, electricity consumption in France in 2021 has increased
by 1.7%. This increase makes it possible to make up for the sharp drop of 3.5% in 2020 due to the health crisis.
Combined-cycle gas turbine power plants: how do they work ?
The electricity production system consists of two cycles, hence the name combined-cycle.
The first cycle takes place in the gas turbine (1).The turbine is made up of four stages: the first stage is a compressor that feeds compressed air into the second stage, which accommodates the combustion chamber where the natural gas is burned. The hot gases produced by combustion then turn fins in the third stage, the expansion chamber. The turbine is attached to a shaft which drives an alternator (3) that produces electricity. The transformer (4) converts the voltage so that the electricity can be fed into the electricity grid (5). The second cycle takes place when the hot gases leave the gas turbine (2). They are fed into a recovery boiler (6) then released into the atmosphere via the chimney. They are composed of roughly 86% air, 9% water vapour and 4% CO2. The steam produced in this boiler is used in a steam turbine (8), which is also linked to the alternator shaft (3). After releasing its energy, the steam is transferred to a condenser (9) and then sent to the recovery boiler in the form of water (10) for conversion back into steam.
Installation of combined cycle gas power
plants in France
Centralized production of electricity from natural gas
(Source : GRTgaz 2021)
A gas combined cycle power plant in a few figures
Average unit power: around 450 GW (depending on the manufacturer)
Average annual production: 2,200-2,500 GWh (annual demand of 450,000 households)
Performance: 58 to 61% (depending on the manufacturer)