A system including a fuel-supply system including, an auxiliary-fuel-gas compressor configured to compress a fuel for use by a gas-turbine system, an expander configured to generate power by expanding an oxidant from the gas-turbine system, and a motor/generator configured to function in a motor mode and in a generator mode, wherein the motor/generator drives fuel compression with the auxiliary fuel-gas compressor in the motor mode, and the motor/generator generates power in the generator mode as the expander uses oxidant from the gas-turbine system to drive the motor/generator.