HAVING decided to shut its nuclear power plants over the coming decade, Germany’s big idea for keeping the lights on is the Energiewende, or energy transition, a state-backed drive towards renewable energy. One of its most ambitious elements is to build 14 gigawatts (GW) of wind turbines off the North Sea and Baltic coasts by 2023, to provide about 9% of the country’s electricity needs by then. In the North Sea eight huge platforms will also be built, each seven storeys high and the size of a football pitch, to collect the output from the windmills, convert it into high-voltage direct current and then send it ashore through cables.

The technology for building and operating this sort of transmission system in the howling gales of the German Bight is largely untried. And once the cables reach shore they will have to pass through populated areas on their way to connect with Germany’s central power grid. To appease NIMBYs (those who reflexively say “not in my backyard”) some of the lines may have to be buried, at further great expense: perhaps 25 times the cost of stringing the cables on pylons. As the project keeps slipping behind schedule the combined cost of the platforms and cables, most recently put at €8 billion ($10.4 billion), looks like rising further.

This risky venture is being taken on, in a sense, by taxpayers next door in the Netherlands, because in 2009 TenneT, the Dutch state-owned power-grid operator, bought the electricity grid that runs down the spine of Germany. It has since been given the job of building the offshore platforms and their cables, and the electricity the project sends ashore will be fed into the central German grid it owns. (Another grid operator, 50 Hertz, has a similar but smaller task in the less windy Baltic.)

So as the project has suffered all sorts of hitches—the latest being second-world-war munitions submerged in the path of one of the transmission lines under construction—it has all got political. Germans have heaped the blame on TenneT and, by implication, the Dutch government. The German power-transmission regulator cancelled the Dutch firm’s operating licence in November, judging it to lack the money to complete the project, only to let it carry on working. The Dutch government has resisted Germany’s requests to put in more capital, since it regards TenneT as an autonomous company.

TenneT was liable for the entire cost and risk of the project, and looked increasingly as though it would be unable to bear them, until a new German energy law was passed last November. Now the contractors building the platforms and power lines (which include Siemens of Germany, ABB of Switzerland and Alstom of France) are liable for part of the tab. So are German electricity customers, through adjustments to the renewable-energy surcharge that is applied to their bills.

Since the change to the law TenneT has brought in Mitsubishi of Japan as an investor in four of the eight platforms. It may bring in other new investors soon, says Lex Hartmann, a TenneT director. So the risk of a complete collapse seems for now to have receded.

But there remains a danger that, even if no further technical hitches arise, the enormous project will end up being a white elephant. Investors have gone cool on building windmills in German waters because of their costs and doubts over future electricity rates. A study, commissioned from an independent consultant by TenneT, reckons that less than 6GW of the planned 14GW of turbines are likely to be built by 2023. If so, laments VZBV, a consumer body, Germans will end up paying heavily for a lot of useless transmission gear out at sea. Those who virtuously slapped bumper-stickers on their cars proclaiming Atomkraft? Nein Danke (Nuclear power? No thanks) may wish they hadn’t.