A method for operation of an engine. The method includes during a first operating condition, permitting intake airflow through an intake air-supply turbine positioned upstream of a cylinder to drive a generator, the generator coupled to an energy storage device, and inhibiting intake airflow through a motor-driven compressor arranged in parallel flow arrangement with the intake air-supply turbine, the motor driven compressor coupled to a motor coupled to the energy storage device. The method further includes during a second operating condition, permitting intake airflow through the motor-driven compressor while the motor-driven compressor receives rotation input from the motor, and inhibiting intake airflow through the intake air-supply turbine.