Large amounts of heat is wasted through air coolers and water coolers for cooling low temperature (<150 degrees C) streams in many technologies. This paper summarizes the results of a study for partial substitute of air cooler, which cools down a hydrocarbon stream from 130 degrees C to 70 degrees C and dissipating heat of 12.1 MW into the environment, by applying organic Rankine cycle (ORC) and Kalina systems. Results showed that the heat energy (Q(H)) recovered in the evaporator were 8.0-8.6 MW for ORC using i-pentane as working fluid and 8.2-8.3 MW for Kalina cycle, respectively. Efficiency (eta) of selected systems obtained at the highest power generated (W-T) was 10.0% (W-T = 862 kW) for ORC and 10.57% (W-T = 996 kW) for Kalina cycle within the design boundaries. Calculated carbon dioxide (CO2) emission reduction potential was 2260 t/y for ORC and 2600 t/y for Kalina system, respectively, at advantageous process conditions. Results showed that Kalina cycle provided higher efficiency and power generation ability on expense of higher system pressure (29 bar-7 bar). Economic calculations showed that the payback time is about 5.0 year for both systems. (C) 2017 Elsevier Ltd. All rights reserved.