Cost-effective configurations of solar-hybrid power plants
This project focused on the development of a solar-hybrid power system with direct heating of a gas turbine's pressurised air. The use of costless solar energy along with the highly efficient combined cycle systems or recuperated gas turbines may lead into significant cost reductions for solar electric power generation. Within this framework, three different gas turbines were selected for building commercial-size solar-hybrid prototype power plants within the power range of 1MWe to 20MWe. One of the options was the "PGT10" working as a combined cycle gas turbine mode (16100MW and 45% efficiency). Pressurised solar receivers featuring low (maximum 600°C), medium (maximum 800°C) and high (maximum 1000°C) temperature with secondary concentrators were employed for the solarisation of these turbines. The concentrating system used involved a glass-metal heliostat and the design solar contribution for the solarised prototype plants was within the range of 38%-88%. On the basis of the optimised system layout, the annual performance simulations displayed valuable information about the technical, economical and environmental potential of the prototype plants. This information was derived under realistic site conditions and used reliable up-to-date cost assumptions. Depending on system size and location, the solar to net electric efficiency ranged between14%-19%. Specifically, for the "PGT10" high temperature configuration the avoided CO2 emissions could reach up to 0.15ton/MWh. For the "PGT10" medium temperature configuration with a 16% solar share operating a whole day, the average levelised electricity cost was very low (0.06 euros/kWh). The incremental cost for the solar contribution related to the solar power fraction was about 0.118euros/kWh. Furthermore, system's operation during sun hours at an increased receiver temperature results in significant increase of the solar share (around 53% for the high temperature configuration). These results have been published in a free accessible project report and various articles proving that the new technology of solar-hybrid gas turbine systems is a key opportunity of renewable power production.
