Solar-heated Rankine cycles for water and electricity production: POWERSOL project

This paper deals with a project entitled POWERSOL (Mechanical Power Generation Based on Solar Heat Engines), partially supported by the European Commission under the Specific programme for research, technological development and demonstration: “Integrating and strengthening the European Research Area” (Specific measures in support of international co-operation, INCO). The main project objective is the development of an environmentally friendly improved-cost shaft power generation technology, based on solar thermal energy, optimized for supplying basic needs to rural or small communities. The proposal focuses on the technological development of a solar thermal-driven mechanical power generation based on a solar-heated thermodynamic cycle (POWERSOL system). This technological development consists in optimizing a solar-assisted thermodynamic cycle that generates mechanical power from low to medium temperature range. The optimization is performed by means of experimental testing of the thermodynamic cycle with selected working fluids and of three solar collector prototypes. Mechanical energy could be either used directly for electricity generation (using a generator) or for brackish or seawater desalination by coupling the output to a high-pressure pump connected to a conventional reverse osmosis system. The main specific objectives of the project are the following: 1) Modeling a solar-heated thermodynamic cycle (selecting the most suitable boundary conditions and working fluids at three different top temperature ranges). 2) Development and construction of three solar collector prototypes optimized for operating around 80 °C, 100–150°C, and 200–250 °C. They are a flat plate collector (static), a compound parabolic or Fresnel concentrator (static) and a parabolic trough collector (sun- tracking), respectively. 3) Experimental testing of solar-driven mechanical power generation and solar collector prototypes. 4) Comparing the cycles at the three temperature ranges for operating autonomously or with energy back-up at different capacity ranges. 5) Full technical evaluation of the proposed POWERSOL technology. 6) Economic assessment of the developed technology against other conventional and solar-driven techniques. 7) Assessment of final potential social and development impact.