Low grade waste heat recovery presents an opportunity to utilize typically wasted energy to reduce overall energy consumption and improve system efficiencies. In this work, the technoeconomic performance of a turbocompression cooling system (TCCS) driven by low grade waste heat in the engine coolant of a large marine diesel generator set is investigated. Five different working fluids were examined to better understand the effects of fluid characteristics on system performance: R134a, R245fa, R1234ze(E), R152a, and R600a. A coupled thermodynamic, heat exchanger, and economic simulation was developed to calculate the simple payback period of the waste heat recovery system, which was minimized using a search and find optimization routine with heat exchanger effectiveness as the optimization parameter. A sensitivity study was performed to understand which heat exchanger effectiveness had the largest impact on payback period. Of the five working fluids examined, a TCCS with R152a as the working fluid had the lowest payback period of 1.46 years with an initial investment of $181,846. The R152a system was most sensitive to the two-phase region of the power cycle condenser. The R1234ze(E) system provided the largest return on investment over a ten year lifetime of $1,399,666.