Power generation by regenerative solar-Rankine plants

In the present paper an originai approach to the use of concentrated solar-thermal technology has been carried on for electric power generation based on Rankine cycles in Mediterranean areas. In particular, the solar energy has been thought as an auxiliary thermal source to face the regenerative part of the thermal cycle (feed water pre-heating), so obtaining major thermodynamics advantages in union with important reduction of pollution. Concerning the solar plant main components, parabolic linear collectors bave been taken into consideration using diathermic oil as intermediate operating fluid, as they are widely utilized today in solar power generation due to their well known reliability (i.e.: mirrors, receivers, photo selective coatings, materials, etc..). A thermodynamic and economical analysis have been provided to estimate the efficiencies and the unit costs of producing energy by different typologies of hybrid power plants compared to conventional ones working by methane gas. The solar energy aid has shown an undisputable thermal effìciency improvements, so reducing the fossil fuel consumption and then the primary cause of air pollution. Regarding the energy cost, some case-studies have shown competitiveness with respect to conventional plant only if social external costs are unavoidably considered, due to the effects of pollutants emissions (fìrst of all, CO2 emissions) onto the environment.