Abstract: A plant operation method having: an exchange step for exchanging a first component provided in a plant for a second component capable of operating the plant with higher performance than the first component; an introduction step for introducing a first program for causing the plant to be operated using the second component with a first performance equivalent to or higher than that achieved when using the first component, and a second program for causing the plant to be operated with a second performance higher than or equal to the first performance; and a switching step for switching between the first program and the second program.

Abstract: An estimate presentation device (110) that presents an estimate for expenses associated with a gas turbine is provided with: a lease charges estimating unit (113) that, when a lease agreement is concluded in which a component of components of the gas turbine which requires regular maintenance is to be leased as a leased component for a desired lease period, estimates lease charges for the leased component; and an estimate presenting unit (116) that presents an estimate for expenses associated with the gas turbine including the lease charges estimated by the lease charges estimating unit (113).

Abstract: A gas turbine plant comprises: a gas turbine having a compressor configured to compress air, a combustor configured to mix compressed air compressed by the compressor with fuel to generate combustion gas, a turbine connected to the compressor and configured to acquire rotary power by the combustion gas, and an air bleeding piping configured to supply the compressed air bled off from the compressor to the turbine as cooling air; and an auxiliary compressed air supply apparatus having a separately placed compressor different from the compressor, a motor configured to rotate the separately placed compressor, and an auxiliary compressed air piping configured to connect the separately placed compressor to the air bleeding piping to supply auxiliary compressed air compressed by the separately placed compressor to the air bleeding piping. The gas turbine further includes a cooling apparatus connected to the air bleeding piping and configured to cool down the cooling air.

Abstract: An estimate presentation device (110) that presents an estimate for expenses associated with a gas turbine is provided with: a lease charges estimating unit (113) that, when a lease agreement is concluded in which a component of components of the gas turbine which requires regular maintenance is to be leased as a leased component for a desired lease period, estimates lease charges for the leased component; and an estimate presenting unit (116) that presents an estimate for expenses associated with the gas turbine including the lease charges estimated by the lease charges estimating unit (113).