In calm conditions in winter there is often frost. This morning there was frost on the ground and the temperature is about zero centigrade (32 F). So wind turbines produce very little power all year round. The sea never freezes around here so a tidal lagoon would be producing the entire demand of 30 – 40 gigawatts of all three countries of Britain,all year round, with enough for export. This is unfashionable common sense. I have experienced temperatures of around 10 – 15 F in New York State in winter (Ithaca and Kingston), so States like New York must be able to generated by hydro as well as other means. I saw a few large dams there in the mountains of New York State. The most famous station is Niagara Falls. I saw that from the Canadian side in November, when the spray froze solid on the trees. Buffalo on the American side can get about eleven feet of snow in one storm, but they are prepared for it.