Solar tower power plants with CO2+SiCl4 mixtures transcritical cycles

The temperature potential of CSP plants is not fully utilized using conventional steam cycles. The next step could be using supercritical CO2 cycles with high-temperature receivers. These cycles can be improved by using the dopants to increase the critical temperature and move towards transcritical cycles, allowing for higher efficiency and lower cost of the power cycle equipment. A CSP plant model to calculate the annual electricity generation and levelized cost of electricity is developed and validated against the results of SAM and SolarTherm. A comparison of steam, sCO2, and CO2+SiCl4 mixture cycles is carried out considering 550 and 700 °C TIT levels representative of Gen2 and Gen3 CSP technologies. The CO2+SiCl4 mixture recompression cycle achieves the highest efficiency, followed by mixture precompression and sCO2 recompression cycles. On the other hand, the lowest LCOE at 550 °C TIT is achieved with solar multiple of 3.4 and 15 h of TES using the CO2+SiCl4 mixture simple recuperated cycle (110.7 USD/MWh to be compared to steam Rankine cycles value of 113.3 USD/MWh and 118.2 USD/MWh of sCO2 partial cooling cycle), because of the power cycle lower cost. At 700 °C TIT, the precompression mixture cycle achieves the lowest LCOE of 113.0 USD/MWh compared to 117.2 USD/MWh of the sCO2 partial cooling cycle. Therefore, the CO2+SiCl4 mixture cycles have higher efficiency and lower LCOE compared to sCO2 cycles, while the lowest LCOE is achieved by the simple and precompression mixture cycle at 550 and 700 °C TIT respectively.