Concrete — though it seems conterintuitive — floats. And floats well. This summer, in the waters off western France, this rock-hard material — used for megaprojects from the ancient Roman dome of the Pantheon to the Hoover Dam — will be tested for its next industrial incarnation: floating wind power.

The flagship of a concrete platform-based concept being built by floating wind pioneer Ideol under the aegis of the EU’s €25m ($26.5m) FloatGen project is racing towards completion at Bouygues Travaux Publics’ yard in the French port of Saint-Nazaire, on track for tow-out this autumn for first trials in open sea.