Low Temperature Thermal Power Concept Case Study

Abstract

Conventional thermal based electrical generating systems utilise high temperature heat energy to generate steam that is in turn used to drive a steam turbine. About 80% of electrical energy used in the world is produced from high temperature heat using a thermodynamic cycle known as the Rankine cycle [website en.wikipedia.org 2013]. In a Rankine cycle heat is applied externally to a closed cycle; water is normally used as the working fluid; typical temperatures are in the above 500^oC range. The usual energy sources are fossil fuels (coal, oil and natural gas), nuclear, biomass and landfill gas, and concentrated solar thermal. However, there is abundant untapped low temperature thermal resources in the form of geothermal, non-concentrated solar radiation, oceanic thermal and process industries waste heat considered not suitable for conventional thermal power plants. Low temperature energy conversion cycles are to a larger extent still a subject of research. Examples of such cycles include Organic Rankine Cycle, Kalina Cycle and Variable Phase Cycle. In this study we present an ORC concept plant based on non- concentrated solar thermal. We also explore several working fluids. Computer simulated results are presented for the proposed non-concentrated solar thermal conversion plant.