Reducing costs of solar power plants
The share of renewable energy systems in the energy supply is expected to double by 2010 as dictated by EC directives. The introduction and, most importantly, the wide spread use of renewable energy sources is one of the most efficient ways for greenhouse gas mitigation. Yet, the abundance of solar energy, particularly in the southern European countries has not been exploited to its full extent mainly due to related costs. Aiming to reduce the costs of solar power plants, the INDITEP project focused on implementing the Direct Steam Generation (DSG) in the absorber pipes of parabolic trough solar collectors. This is expected to bring a 26% reduction in the cost of electricity produced by these power plants. On the basis of previously gained experience, the INDITEP project partners joined forces to introduce the DSG technology into the energy market. To this end, an engineering detail design of a 5MWe pre-commercial DSG power plant was developed. This involves basic electrical, mechanical, control, instrumentation and civil engineering of a DSG solar field. The detail of the design is necessary as it sets the key requirements for procuring components and implementing the first commercial plant. The basic design concept was the coupling of a DSG solar field to a power cycle delivering 5MWe net electrical power. In accordance with the requirements of the steam turbine, parabolic trough collector loops were sized and process values were defined. Through an iterative process, solar-to-electric efficiency of the power plant was maximised. Power cycle-solar field integration issues were carefully studied in order to identify specific equipment that is closely related to start-up and shut-down procedures for the power plant. By adopting a hybridised Rankine cycle, a thermodynamic cycle that uses steam as working fluid and exploits heat, the design of the first DSG power plant was accomplished.
