I understand that just ONE rotation of the blades on a single large wind turbine creates enough power for a normal house for a full day. With water being so much denser than air, and with the tides being entirely predictable compared with wind, and with the UK experiencing some of the highest tidal differences in the world (30 feet on the west coast) I cannot understand why tidal power has not featured more in our power supply planning. I read somewhere that a properly planned tidal power plant built into the newest Severn Bridge, that incorporated suspended turbines (for easier maintenance and less disruption to marine life), would have been as productive as the 3 largest wind farms in the North Sea. I can't remember the exact figures but I think 2 or 3 Gigawatts was mentioned. It seems to me to be an obvious alternative or addition to our portfolio compared with some others. Maybe there are practical and scientific reasons why tidal power is not the answer that I'm not really understanding or fully grasping, but it wouldn't surprise me if there wasn't some sort of lobbying conspiracy against tidal power, driven by pure profit.