The power system comprises a working fluid circuit having a high pressure side and a low pressure side and configured to flow a working fluid therethrough. The working fluid circuit further comprises a heater configured to circulate the working fluid in heat exchange relationship with a hot fluid to vaporize the working fluid. The system further comprises serially arranged first expander and second expander fluidly coupled to the working fluid circuit and disposed between the high pressure side and the low pressure side thereof. One of the expanders drives a load and the other expander drives a pump or compressor fluidly coupled to the working fluid circuit between the low pressure side and the high pressure side thereof. A cooler is further arranged and configured to remove heat from the working fluid in the low pressure side of the working fluid circuit.