Rosie Barnes, founder of Pardalote Consulting, explores the engineering, commercial, and geopolitical challenges of building a global subsea HVDC electricity grid capable of connecting continents.
Key insights:
Subsea cables must use high-voltage direct current rather than AC because seawater acts as a capacitor that wastes AC power, and higher voltages reduce transmission losses over thousands of kilometers.
Laurent Segalen of NATO-L frames the core technical challenges as four D’s — design, depth, distance, and damage — with distance being the hardest, requiring a jump from today’s 525 kilovolt standard to 800 kilovolt cables not yet commercially available.
The biggest physical threat to cables is not hostile submarines but fishing anchors in shallow water, which burying cables to 150 meters depth reduces by 95%, while cybersecurity is the more serious operational concern.
Project leaders from NATO-L and Xlinks compare the likely trajectory to the internet cable rollout of the 1980s and 1990s; and the harder barriers to a global grid are political trust between governments and project financing rather than engineering itself.