Optimization and evaluation of subsea cooling for the offshore wind industry
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Sustainable energy systems (MPSES), MSc
Quality and operations management (MPQOM), MSc
Quality and operations management (MPQOM), MSc
Publicerad
2024
Författare
Täck, Elsa
Blomberg, Jonathan
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
With an expanding energy market and an increasing focus on developing green, reliable and sustainable energy, the demand has never been greater for new innovations meeting these criteria. Today, offshore wind stands as a front-runner amongst the renewable energy alternatives. For the technology to be truly competitive against fossil fuels, the method of transporting large amounts of generated power long distances must be improved. High Voltage Direct Current (HVDC) has proven to be a promising technology offering low transmission losses over greater distances. However, the conversion process from Alternating Current (AC) to Direct Current (DC) which takes place on offshore HVDC platforms is generating a significant amount of heat, resulting in a high cooling demand. Conventional cooling systems are energy consuming and utilize chemicals in the cooling process which are discharged to sea.
This thesis has investigated an alternative cooling solution, utilizing subsea cooling and a closed loop. The alternative cooling solutions is free of chemicals and was found to be far more energy-efficient in terms of operating cost compared to
conventional cooling. The thesis also screened the future market for HVDC platforms in the North Sea and its cooling demand, by conducting a progressive market screening. It was concluded that the market is set to triple in terms of amount of HVDC platforms to be established and seven-fold in terms of installed converting capacity over the next seven years. A passive subsea cooler, operating in a closed loop utilizes natural convection and has a unique design to withstand shallow water conditions and lower coolant temperatures. Computational fluid dynamics (CFD) simulations have been performed to evaluate different cases of pipe arrangement and chimney designs to investigate the performance of the proposed subsea cooler. Manufacturing possibilities and their implications were also investigated together with a techno-economic discussion which presents various design alternatives.
The study has concluded that, compared to existing technologies in the market, the closed loop cooling system decreases overall operating energy consumption and removes chemical pollutants that previously have been the base case for cooling
offshore HVDC platforms. CFD simulations were proven to be an important tool in testing the passive subsea cooler performance. It was identified that baffles and large temperature differences are crucial in enhancing a passive subsea cooler. The thesis also managed to reduce computational time for the full 3D simulation by 96%, to test the chimney design.
Beskrivning
Ämne/nyckelord
offshore wind , passive cooler , high voltage direct current , offshore platform , computational fluid dynamics , market screening , subsea cooling