Electricity from Geothermal Energy with the Kalina Cycle An Exergy Approach

The geothermal energy that is stored in the earth is so vast that could supply all the energy needed by humanity. The difficulty in tapping this energy lies in its diffusivity. The geothermal energy in regions close to volcanoes is close to the surface and easy to use economically. In this paper a vapor dominated system will be examined. The electricity that is produced from such a system is economically and environmentally in a better position than the electricity produced from coal or diesel. The Kalina cycle will be used in this system and an exergy analysis is performed. The Kalina cycle is a new concept in power generation and uses a mixture of 70% ammonia and 30% water as the working fluid with the potential to increase the exergy efficiency over the Rankine cycle. The exergy analysis will provide a qualitative and quantitative picture of the process.