Wedoany.com Report-Oct 24,   One big challenge of the switch to renewable energy is unreliability. Critics often ask what happens when the sun doesn’t shine, and the wind doesn’t blow? But there is one renewable source which is consistent and never stops. For millions of years, the moon has been pulling all the water in the earth’s oceans up and down with absolute consistency for 22+ hours a day. That is a gigantic amount of energy.

And the UK is one of the places where the effects are greatest. There is only one place on earth where the tidal range is higher than the south west of England, where it rises and falls by 10 metres every day. Meanwhile, tides pull vast quantities of water between the Atlantic and North Sea through narrow gaps between Scotland, Orkney and Shetland.

Tidal power works by channelling water through turbines. The most established way uses reservoirs, which fill as the tide rises and empty as it falls. Turbines are driven by the flow. When this works in both directions, the energy supply is almost constant. This is the principle of the tide mill, which was a feature of coastal communities from early medieval times. Until the nineteenth century, East Anglia had many, grinding grain and fulling cloth, and Woodbridge still has the last tide mill in working order in England.

But now tidal energy is being considered on a much larger scale, for electricity generation. The principle has been used successfully in Brittany, where the Rance estuary was dammed in 1966 to generate electricity, and is still producing 240 megawatts of electricity. It is also the principle proposed for the abandoned Severn Barrage, which would have captured the power of the huge tidal rise in the Severn estuary, but at high financial and environmental cost. And recently such a barrage has been proposed across the Wash, where it would also provide new harbour facilities, and a direct road link from Norfolk to Lincolnshire.