The supply chain is worth pausing on. The platform was designed by Aibel, a Norwegian company whose roots are in offshore oil. It was fabricated in the United Arab Emirates by Drydocks World, a Dubai government-owned yard that had spent decades building offshore vessels for the Gulf oil industry. It was towed across the Mediterranean and up the Atlantic to Haugesund on Norway's south-western coast, where Aibel completed the high-voltage fit-out — switchgear, transformers, ABB's modular multi-level converter — in a fjord protected from the worst of the weather. It sailed out under tow on 1 August 2015 and was installed in the German Bight ten days later, ready to transmit electricity that would not exist for another two years.

Most offshore platforms are lifted onto fixed jackets by purpose-built heavy-lift vessels — slow, expensive operations that depend on calm weather and tight scheduling. DolWin Beta dispensed with that ritual. The platform was floated to its position on its own buoyancy, then lowered itself onto a pre-installed foundation by carefully managing its ballast tanks. The technique borrowed directly from the oil industry's tension-leg platforms but had never been applied to an HVDC project. If the installation went badly, you would lose a billion-euro asset to the open sea. It went well. The whole industry took notes.

Once handed over to TenneT in 2017, DolWin2 became the gathering point for an entire neighbourhood of turbines: 332 megawatts from Gode Wind I, 252 megawatts from Gode Wind II, and 332 megawatts from Nordsee One — a combined 916 megawatts of generating capacity, more than DolWin2's 900-megawatt rating once you account for transmission losses. The link runs at ±320 kV across 135 kilometres of cable to a converter station near Dorpen West in Lower Saxony, where the DC current becomes AC again and joins the national grid. Three wind farms, one set of cables, one quietly humming yellow box in the sea.

It is worth understanding why all this trouble was worth taking. AC transmission over long subsea distances loses power to capacitive charging — past about 80 kilometres the losses become prohibitive. HVDC eliminates that problem by sending current in one direction, but it requires expensive conversion at each end. The break-even point for offshore wind sits at roughly the distances Germany has chosen to build at — far enough from shore to avoid sight lines from holiday islands, close enough that the conversion penalty stays manageable. DolWin2 is a working answer to that arithmetic. It is also, like its sibling DolWin1, a kind of monument to globalisation: a Norwegian-designed, Emirati-built, Swedish-Swiss-financed platform planted in German waters to carry Danish wind.