A gas turbine engine is provided comprising a compressor, a fuel supply apparatus, a combustor, and a turbine. The fuel supply apparatus comprises a fuel source, a cooling apparatus including a heat exchanger and structure for defining a first path for fuel to travel from the fuel source to the heat exchanger and a second path for fuel to travel away from the heat exchanger. The combustor functions to receive the compressed air from the compressor and the fuel from the heat exchanger, combine the air and fuel to create an air/fuel mixture and ignite the air/fuel mixture to create combustion products. The cooling apparatus further comprises structure coupled to and extending between the heat exchanger and at least one of a plurality vanes in the turbine for circulating a coolant fluid through at least one vane and the heat exchanger. In another embodiment, pipe supply structure extends from a fuel source through an end section of a turbine casing. In a further embodiment, a heat exchanger of a heat recovery steam generator is provided in a turbine casing end section.