Novel Geothermal Plant operating on Kalina Cycle

Abstract

One of the novel applications of Geothermal Energy is the development of Power plant based on Kalina Cycle (KCS 11), which is applicable to low temperature geothermal plants which is a closed cycle in which a water and ammonia mixture (NH3-H2O) serves as the transfer medium (refrigerant). Unlike pure substances, which remain at a constant temperature during boiling or condensation, an ammonia-water mixture has a varying boiling and condensing temperature. Also, the thermo-physical properties of an ammonia-water mixture can be altered by changing the ammonia concentration. Geothermal Water present inside earth’s crust at a temperature of 121˚C is pumped to the surface to heat the ammonia-water mixture in the evaporator. After which this mixture enters a separator, where liquid is separated from vapour. The vapour, rich with ammonia (NH3), is then led through a turbine to generate electricity for commercial purposes. The geothermal water leaving the evaporator at a temperature of about 71˚C can then be used either for district heating purpose in cold countries or for industrial purposes. Kalina Cycle has a higher efficiency and lesser operational cost than other cycles such as Organic Rankine Cycle (ORC) which are currently used in many power plants. Due to its higher efficiency, the physical size of certain equipments in power plants will be smaller.