Desolination Project sCO2 Axial Expander development

sCO2 energy conversion cycles technology development is reaching the MW-scale cycle demonstration phase. At the moment of this abstract writing, the STEP plant is going through the different phases of commissioning and has already produced electrical power. Other demonstration projects are reaching the end of the design phase and forecast a commissioning start in 2026. Nuovo Pignone Baker Hughes is part of the Desolination project consortium. Desolination project aims to decarbonize the desalination process in arid regions by demonstrating in a real environment the efficient coupling of a concentrating solar power plant to a direct osmosis desalination system. The sCO2 cycle involved in this process is a Transcritical evolving a blended CO2 mixture optimized to enable condensation in hot ambient temperature areas. Nuovo Pignone contributes to the Desolination project developing the pump and the expander of the sCO2 cycle. Expander development has reached the completion of the detailed design phase and the procurement of long lead material has started. This paper will provide a comprehensive overview of the expander development process, from conceptual design through to detailed design, displaying the key technology challenges peculiar of sCO2 expanders and illustrating the engineering methodologies applied to optimize the expander design.