With a high back-work ratio and a high exhaust-temperature, the simple cycle gas-turbine generation system usually has a low generation-efficiency especially when the ambient weather is hot. Among many technologies to improve the efficiency of a simple-cycle gas-turbine, inlet-air cooling, and steam reinjection are considered the best ways to modify an existing simple cycle unit without major destruction to its original integrity. To evaluate the individual effects after system modifications, a computer code for the simulation of the power-generation system was developed and validated in this study, and the ABSIM code developed by Oak Ridge National Laboratory was adopted to simulate the absorption refrigeration system. Based on the calculated improvement and the associated benefits, the estimated cost of refurbishment and other operational costs, economic analyses were performed under the current fuel and cost structures. Results indicate that the system with the steam reinjection feature has the highest generation-efficiency and thus the most potential profit on investment, while the system with both inlet-air cooling and steam reinjection features can generate the highest power-output and release the least exergy via the flue gases. (c) 2006 Elsevier Ltd. All rights reserved.