Method for generating electricity and storing energy via a thermal power plant or a nuclear power plant and an apparatus for vaporising liquid, wherein A) during a first period: a) i) thermal energy is produced via the thermal power plant, flue gas is produced, at least a portion of the flue gas is used to vaporise water or to heat water vapour, the water vapour formed is expanded in a first turbine and the first turbine is used to drive an electricity generator in order to produce electricity or ii) thermal energy is produced via the nuclear power plant and the thermal energy is used to vaporise water or to heat water vapour, the water vapour formed is expanded in a first turbine and the first turbine is used to drive an electricity generator in order to produce electricity b) liquefied gas coming from a cryogenic storage is vaporised in order to produce a pressurised gas c) the pressurised gas is heated and d) the pressurised fluid is expanded in a second turbine in order to produce electricity and e) in order to heat the pressurised fluid, a portion of the thermal energy produced in step a) is used to heat the pressurised fluid by using a portion of the flue gas of the thermal power plant or a portion of the water vapour intended for the first turbine of the thermal or nuclear power plant or a portion of the heat of the water vapour intended for the first turbine of the thermal or nuclear power plant in order to heat the pressurised fluid and B) during a second period: a') thermal energy is produced via the thermal or nuclear power plant and the thermal energy is used to generate electricity, b') electric and/or mechanical energy generated by the power plant is used to liquefy the gas and c') the liquefied gas is stored in a storage. A) during a first period: a) i) thermal energy is produced via the thermal power plant, flue gas is produced, at least a portion of the flue gas is used to vaporise water or to heat water vapour, the water vapour formed is expanded in a first turbine and the first turbine is used to drive an electricity generator in order to produce electricity or ii) thermal energy is produced via the nuclear power plant and the thermal energy is used to vaporise water or to heat water vapour, the water vapour formed is expanded in a first turbine and the first turbine is used to drive an electricity generator in order to produce electricity b) liquefied gas coming from a cryogenic storage is vaporised in order to produce a pressurised gas c) the pressurised gas is heated and d) the pressurised fluid is expanded in a second turbine in order to produce electricity and e) in order to heat the pressurised fluid, a portion of the thermal energy produced in step a) is used to heat the pressurised fluid by using a portion of the flue gas of the thermal power plant or a portion of the water vapour intended for the first turbine of the thermal or nuclear power plant or a portion of the heat of the water vapour intended for the first turbine of the thermal or nuclear power plant in order to heat the pressurised fluid and a) i) thermal energy is produced via the thermal power plant, flue gas is produced, at least a portion of the flue gas is used to vaporise water or to heat water vapour, the water vapour formed is expanded in a first turbine and the first turbine is used to drive an electricity generator in order to produce electricity or ii) thermal energy is produced via the nuclear power plant and the thermal energy is used to vaporise water or to heat water vapour, the water vapour formed is expanded in a first turbine and the first turbine is used to drive an electricity generator in order to produce electricity i) thermal energy is produced via the thermal power plant, flue gas is produced, at least a portion of the flue gas is used to vaporise water or to heat water vapour, the water vapour formed is expanded in a first turbine and the first turbine is used to drive an electricity generator in order to produce electricity or ii) thermal energy is produced via the nuclear power plant and the thermal energy is used to vaporise water or to heat water vapour, the water vapour formed is expanded in a first turbine and the first turbine is used to drive an electricity generator in order to produce electricity b) liquefied gas coming from a cryogenic storage is vaporised in order to produce a pressurised gas c) the pressurised gas is heated and d) the pressurised fluid is expanded in a second turbine in order to produce electricity and e) in order to heat the pressurised fluid, a portion of the thermal energy produced in step a) is used to heat the pressurised fluid by using a portion of the flue gas of the thermal power plant or a portion of the water vapour intended for the first turbine of the thermal or nuclear power plant or a portion of the heat of the water vapour intended for the first turbine of the thermal or nuclear power plant in order to heat the pressurised fluid and B) during a second period: a') thermal energy is produced via the thermal or nuclear power plant and the thermal energy is used to generate electricity, b') electric and/or mechanical energy generated by the power plant is used to liquefy the gas and c') the liquefied gas is stored in a storage. a') thermal energy is produced via the thermal or nuclear power plant and the thermal energy is used to generate electricity, b') electric and/or mechanical energy generated by the power plant is used to liquefy the gas and c') the liquefied gas is stored in a storage.