1) We were in Wales in 2019 and visited one of the pumped storage systems. The staff there were quite clear that it take more power to pump the water up that produces power on the way down, they do it because it enables them to have a source of power that is instant in its availability and can be turned on whenever extra power is needed in a hurry.
2) Tidal power requires an area which has a high tidal range. The best place for it in the UK is the Bristol Channel.
A project to put a barrage across part of the river Severn, , was seen off by the RSPB and other environmentalists, who put short term wildlife issues, well before thinking of extinctions that will be the result of global warning.
A consortium of investors put forward a plan for a series of tidal lagoons along the South Wales coast. The firsts of which is at Swansea Bay [[www.tidallagoonpower.com/projects/swansea-bay/ ]] which would have been able to provide electricity 24/7 for over 150,000 homes for 120, yes, 120 years. Unfortunately the proposal was rejected by the government.
The French installed their first tidal power station in 1964, General de Gaulle opened it. It is across the river Rance, in northern Brittany near St Malo. I have been there. It has now been running for nearly 60 years. turbines have been replaced at various times, but the power keeps being generated.
Why the British government is so slow in supporting them I cannot imagine.
3) Tidal/wave power. This is like fusion, it is always 10 years ahead. This article, written six years ago is very informative, but it an article that could have been written anytime in the last 30 years because lots of people dicker with schemes, but no one has yet been ablt to deliver the goods.//e360.yale.edu/features/why_wave_power_has_lagged_far_behind_as_energy_source