Pumpkin-shaped, underwater, compressed-air-storage devices being trialled at the University of Nottingham could prove key to overcoming one of the main obstacles to Europe’s long-term ambitions for utility-scale renewable-energy production — that peak power-generating times from offshore wind farms rarely match peak demand for electricity onshore.

Being developed by a group in the mechanical, materials and manufacturing engineering department led by professor Seamus Garvey, the steel and polymer ‘energy bags’ are designed to be pumped full of high-pressure air during times of high winds and low demand, with the stored energy used to turn turbines to create electricity when needed on the grid.