This is a brand-new type of solar-thermal power system/plant that can generate power from a low temperature heat source (fluids in natural environment, such as seas, lakes, rivers, groundwater or atmosphere). The unique feature of Injection Power Cycle is that the temperature range in which it takes place is greater than the temperature difference between heat a source and heat sink. This results in the increase of amount of work and, therefore, the raise of efficiency of the power cycle. In conclusion, for given temperatures of a heat source and a heat sink, the Injection Power Cycle is the most efficient power cycle.