On july 16th Royal Dutch Shell, an oil and gas company, and Scottish Power, a subsidiary of Iberdrola, a Spanish electricity utility, made an announcement. They were, they said, jointly submitting proposals to the British authorities to build, off the coast of Scotland, the first large-scale set of floating wind farms in the world. At the moment, the largest floating farm is a six-turbine, 50mw array which is due for completion next month in the North Sea, 15km from Aberdeen. The consortium, by contrast, has said it is thinking in gigawatts (GW).

Offshore wind farms with foundations in the seabed are now part of the energy mix in several places. In the past four years their capacity has nearly doubled, from 19gw to 35gw, and amortised costs...

Floating wind turbines could rise to great heights