A power generation system includes a heating fluid circuit thermally coupled to multiple heat sources from at least an integrated hydrocracking plant and diesel hydro-treating plant of a petrochemical refining system. A first subset of the heat sources includes diesel hydro-treating plant heat exchangers coupled to streams in the diesel hydro-treating plant. A second subset of the heat sources includes hydrocracking plant heat exchangers coupled to streams in the hydrocracking plant. The heat exchangers are connected to a power generation system that includes an organic Rankine cycle (ORC) including a working fluid that is thermally coupled to the heating fluid circuit to heat the working fluid, an expander configured to generate electrical power from the heated first working fluid, and a control system configured to activate a set of control valves to selectively thermally couple the heating fluid circuit to at least a portion of the heat sources.