Well - the UK govt is considering a range of plans for developing the Severn right now, so I wouldn't say they have given up on the idea - they are just very slow moving.

Some of the best sites in the Kimberly (like the one pictured) are narrow, fjord like formations - you are right that presumably they would have some sort of barrage built across them.

Tidal turbines could also be used I guess, but they wouldn't generate as much power.

Nice post Gav,

The tide pattern around NZ is amazing - if it's high tide on one side of the islands it's low tide on the other, and Cook Strait conveniently connects the two!

A fascinating animation here:
http://www.teara.govt.nz/EarthSeaAndSky/OceanStudyAndConservation/OceanC...