Thermodynamic assessment of a wind turbine based combined cycle

Combined cycles use the exhaust gases released from a Gas Turbine (GT). Approximately 30–40% of the turbine shaft work is typically used to drive the Compressor. The present study analyzes a system that couples a Wind Turbine (WT) with a combined cycle. It demonstrates how a WT can be used to supply power to the Compressor in the GT cycle and pump fluid through a reheat Rankine cycle, in order to increase the overall power output. Three different configurations are discussed, namely high penetration, low penetration and wind power addition. In the case of a low electricity demand and high penetration configuration, extra wind power is used to compress air which can then be used in the low penetration configuration. During a high load demand, all the wind power is used to drive the pump and compressor and if required additional compressed air is supplied by a storage unit. The analysis shows that increasing the combustion temperature reduces the critical velocity and mass flow rate. Increases in wind speed reduce both energy and exergy efficiency of the overall system.

► This study analyzes a system that couples a wind turbine with a combined power generation cycle.
► Surplus wind power is used to compress air, which is then stored and used at a later time.
► Increasing the pressure ratio will reduce the work ratio between the Rankine and Brayton cycles.
►  A higher combustion temperature will increase the net work output, as well as the system energy and exergy efficiencies.