How Does Tidal Power Work?

Tidal power works much like hydroelectricity in that it uses the movement of water to power a turbine to create electricity. Usually, a barrage is built across the estuary of a river, and the ebb and flow of the tide is used to turn a turbine. Lock gates in the barrage allow boats and ships to pass through. The energy that could be produced from these sources is potentially huge, but there are very few sites in the world that are appropriate, and the ecological disturbances associated with building barrages is more than considerable. Off shore sites are far more promising, and the first of these can be seen here.

The Development of Tidal Power

La Rance tidal energy barrage is possibly the most well known and successful in the world, but it relies on the total capture of an estuary’s tidal waters with the resultant effects on the marine environment. Such schemes are not very likely to be adopted in the UK, partially due to environmental concerns, but also because newer methods are now available.

The Severn Estuary has one of the highest tidal ranges in the world and probably the best way to exploit this would be to build a “linked lagoon” tidal system. With this system a series of lagoons are filled by the incoming tide and each is emptied in sequence to generate electricity so that the periods at the top and bottom of the tide do not create a period of zero generating capacity. Another advantage of this system is that it does not feed a massive amount of electricity into the national grid over a very short time period. Such schemes are unlikely to be initiated, due to the privatisation of electricity generation and the resultant reduction of finance, from the government and banks, for such massive schemes.

The Future of Tidal Power

It is in the development of smaller, less environmentally-damaging schemes, that the greatest progress has been made by generating electricity from tidal streams, rather than the potential energy of trapped tidal waters. By placing these smaller devices around the coast of the UK, a more stable input to the grid could be achieved, due to the variation in the timing of the tides around the British Isles. For this reason, tidal stream devices are ideal for base load generation. As some tidal stream devices use similar technology to wind turbines, they may benefit from wind turbine technological developments to considerably reduce the cost of their own research and development, thereby giving these devices a market advantage. Also, it may be possible to reduce costs, further, by combining a tidal stream device below the water, with a wind turbine above, on the same seabed foundation.