One embodiment of an improved thermal power cycle comprising a wet binary motive fluid, pump (21), evaporator (22), expander (23), and condenser (24). Using a binary motive fluid, it can operate efficiently over a lower range of heat source temperatures than the steam Rankine cycle. Using a wet binary motive fluid, it eliminates the need for superheating the fluid in evaporator (22), allows for complete expansion of the fluid in expander (23), and reduces back-pressure by the fluid on expander (23), thereby providing higher efficiency than the ORC (organic Rankine cycle), Eliminating the regenerator that is used by ORC systems results in a simpler, less costly system. Using direct-contact heat exchange in condenser (24) rather than the indirect-contact heat exchange used by ORC systems results in more efficient condensation of the fluid. Using a pump (21) rather than the power-hungry compressor used by ORC systems further reduces power losses and expenses. Accordingly, the improved cycle provides higher overall system efficiency at lower overall system cost. Other embodiments are described and shown.