No argument there regarding tidal energy but like all renewable energy generation the problem at the moment is what happens when the tide is out , no generation ,from solar energy when the it's dark no generation , out of the three sources wind is a constant and although variable in it's strength and direction it is, believe it or is predictable and that assists in balancing generation loads on the Grid. Turbines can operate and generate at quite low wind speeds so it is rare in this country to see a totally non operating wind farm both day or night.The trick for all renewable energy is when it's created how can it be stored, unlike powers stations which can increase or reduce capacity the others cannot which means the power generated has to be used or wasted .
As a local diver I can tell you Matt that the change around is about an hour before the tide starts surging in again. There shouldn't be a problem. However, I understand that the issue is the initial outlay to make the thing and how long it would take to get the money back.
Tides come in and out different times of the day around our island so you would always have power feeding the national grid. Im sure the boffins in this field can design a system that will work using power stations we already have....
The tide does indeed turn around the hour mark so to benefit from the full tidal range then the generator has to be positioned accordingly .Like everything there has to be the initial investment and obviously a return on that investment that seems to be the stumbling block at the moment regarding the Swansea tidal lagoon .The technology does exist and has been proven to work but we as country seem to lack the vision to grasp the opportunity when it's presented , hence smaller builds dotted around the country such as the one in Ramsey sound in Pembrokeshire
There are estuarys around the UK that have a constant flow e.g. Ramsey Sound however there is a problem that silt may block the turbines. I believe they have been experimenting in Ireland to see if this could be overcome but I haven't seen any results. The other problem is the possible ill effect on wildlife which I am sure none of us would want to see.
Having had a quick scan through this, I agree with most of what's been said here. No to Welsh Assembly, or at least serious reform of the way it's run. No to wind farms. Yes to tidal power.