The world demand for energy is expected to increase continuously, and limited resources of fossil fuel will be exhausted sooner or later which may lead to energy crisis. In addition, the accelerated consumption of fossil fuel has caused many environmental problems such as atmospheric pollution, ozone layer depletion, and global warming which became a main concern for people. On the contrary, the amounts of low/medium grade heat sources such as solar energy, geo-thermal energy and waste heat energy are enormous and considered as the promising alternative sources that can provide a major contribution to the world electricity demand. However, the moderate temperature heat from these sources cannot be converted efficiently by conventional methods. In this context, the search on how to convert these moderate sources to electricity gains a great significance. This report gives an up to date review on recent developments and studies carried out on steam power cycles exploiting low-grade heat. The design and performance of cycles have been considered carefully and results obtained are presented and compared where appropriate. The choice of working fluid is vital to the performance of cycles and to the environment. The use of halocarbon compounds, hydrocarbon compounds, binary mixtures as working fluids are reviewed. Combined cycles and cooling/refrigeration cycles are the main applications of absorption cycle. These applications are studied and various configurations are presented along with results obtained.