If Tidal Power was the way forward, efficient, viable.... the private sector would be queuing up to crack on.
Interest rates are diddly squat, so if you can put investment in to something that might yield a decent return on investment why not?
We will all need electricity and demand will almost certainly grow, carb0on based generation in the West will become more difficult.
Judging from some of the EMEC companies around the Pentland Firth, there's lots of seed money available, but they are waiting as they want some Govt subsidy as we've seen with on and offshore wind over the years and SOLAR.
Scrap all subsidy, offer investment incentives instead, see what the market leads to. It could be tidal.