> Incidentally, the argument that the tide is more reliable as it always flows twice a day is a rather moot point, as like wind, the tide doesn't always flow when you want it to.

Producing energy on a completely predicable schedule, while being less useful than at will, is much easier to deal with than producing energy on a modestly predictable but highly variable basis.

But on the general point about funding for tidal energy I agree with you. To make it work we'd need to make bold and highly disruptive changes to the environment, for example the tidal barrier across the Bristol Channel.