Gas engines used for electricity generation release significant amounts of waste heat through exhaust gases and hot water circuit. To effectively recover waste heat, a novel dual-loop organic Rankine cycle is proposed. The proposed cycle consists of a basic organic Rankine cycle in the high-temperature loop and a dual-pressure organic Rankine cycle in the low-temperature loop. The high-temperature loop utilizes the exhaust gases as its heat source, while the low-temperature loop employs the residual heat from the high-temperature loop for its highpressure evaporator and the hot water circuit for its low-pressure evaporator. This configuration allows all heat exchangers to operate above atmospheric pressure and below critical temperatures of the working fluids. Energy, exergy, economic, and thermoeconomic analyses are conducted to evaluate the performance of the proposed cycle. Moreover, the cascade-expansion organic Rankine cycle is analyzed as a benchmark solution for comparison. The effects of key design parameters are investigated for parametric analysis, and both cycles are optimized using a genetic algorithm by defining energy efficiency and unit cost of exergy as independent objective functions to obtain thermodynamic and thermoeconomic optimum designs. In the thermodynamic optimum design, the dual-loop organic Rankine cycle produces 239.82 kW of net power with 16.50 % energy efficiency and 62.09 % exergy efficiency, while cascade-expansion organic Rankine cycle yields 184.30 kW, 12.68 %, and 47.71 %, respectively. The dual-loop organic Rankine cycle also offers economic advantages, with a lower specific investment cost, levelized cost of electricity and unit cost of exergy compared to the cascade-expansion organic Rankine cycle.