Actually one of the better free energy schemes! Who could object?
Surfers??

I would like to see these projects do well but at £3m a MW and knowing what the marine environment is like for wear and tear I am not hopeful.
Are there any numbers on how much energy can be captured from renewables and at what costs?
I believe the numbers are pretty rubbish, happy to be corrected if this isn't true. A lot of renewables stuff is fairly useless in the near term but can be regarded as investment in knowledge. That Severn barrier is an exception and looks like a must-have to me, can't see why they don't just get the f*ck on with it.
Wind and solar PV will be OK in time if we find a way of storing energy efficiently, if there were a few fjords that could conveniently be used as mega-reservoirs (as in Norway) then they could pump water as energy storage, but in a flattish, populous nation it's tricky. It's no good having the UK 35% wind-powered if there's no wind for a week, France may not be able to sell us enough power to make up the difference.
For the moment IMO we should be making massive investments in reducing household and business energy consumption. Insulation, LEDs for lighting, Solar Thermal for water-heating, encouraging efficient machines (eg no plasma TVs, LED only), zero-power standby mode, simple things that actually make a difference very quickly.