COMPARED with solar and wind energy, which are booming, tidal power is an also-ran in the clean-energy stakes. But if you did want to build a tidal power station, there are few better sites than the estuary of the River Severn, in Britain. Its tidal range, the difference in depth between high and low tides, of around 15 metres is among the largest in the world.
Engineers and governments have been toying with the idea since at least 1925. But none of the proposed projects has materialised. Price is one objection. A study by Britain’s National Infrastructure Commission, published last year, reckoned that tidal energy might cost between £216 and £368 ($306-521) per MWh of electricity by 2025, compared with £58-75 for seagoing wind turbines and £55-76 for solar panels. Environmentalists also worry that any plant would alter the tides it was harnessing, making life harder for wildlife.