Tidal-power developments by British firms show this renewable power technology achieving impressive scale and continued design innovation. Bristol-based Marine Current Turbines (MCT) revealed last month that its SeaGen dual-turbine system achieved full power operation of 1.2 megawatts. MCT's power peak is four times the global record for a tidal-stream system set by the company in 2004, according to U.K.-based renewables journal REFocus, and 30 times more than the output from the tidal turbines pumping electricity in New York's East River.

An artist's impression of MCT's SeaGen.

Meanwhile, the U.K. Guardian reported yesterday that more large-scale demonstrations are on the way as Cardiff-based Tidal Energy prepares to test a one-megawatt version of its triple-rotor design off the coast of Wales by next year.

Hitting full power clears a major hurdle for MCT. As Technology Review reported last July, the company suffered a setback early on when the powerful tidal streams of Northern Ireland's Strangford Lough damaged one of its blades shortly after installation. In an odd way, it's an affirmation of MCT's design, which enables the dual rotors to be lifted clear up out of the water for easy maintenance and repair.

While at a considerably earlier phase of development, MCT rival Tidal Energy's triple-rotor concept provides an equally innovative means of ready repair. Tidal Energy's rotors sit at the corners of a three-legged platform that can be deposited on the seabed and held in place by the system's 250-ton heft. That should not only ease recovery of the system for maintenance, but also simplify installation by eliminating the need for a fixed foundation in the seabed.

To see these concepts in action, check out the MCT animation below and Tidal Energy's animation.