Abstract
British people of a certain age may have fond memories of watching the Salter tiny wave device-bobbing up and down in a wave tank powering a small in the Tomorrows World studio on BBC1, no doubt murmuring sagely that future of power generation for an Island nation such as the UK. (1)
Those same viewers may have visited a tidal power mill in the UK- such on the south coast- or gazed in awe at the power of the flood tide as it flows channel, or watched the waves as they crash onto our shoreline.
So where are we 25 years on from the Salter duck in harnessing the waves? much further advanced are we than our ancestors who built the Eling tide significantly closer to realising the dreams of our forefathers who 100 years plans to build a barrage across the Severn to harness the power of the second tidal range in the world? (2)
The Eling tide mill web site contains the following information; "The ONLY regularly working tide mill IN THE WORLD-AND IT STILL PRODUCES FLOUR DAILY! See natural tidal power, harnessed in a centuries old (900 years) tradition, producing stone ground organic wholemeal flour from English wheat. The mill is open Wednesday to Sunday from 10.00 am- 4.00 pm. For milling times visit: (3)
That the tide was being harnessed 900 years ago to produce one of the basics of the age- flour- is clearly a close analogy to our current desire for the tide to produce one of the most basic needs of our own time-electricity.
The drawbacks of tidal technology can be seen in the need to ask for milling times. The tide moves in and out and doesn't always have the capacity to generate power. Similarly those observers of the waves crashing on our shore will recognise that sometimes the sea is like a mill pond. So in some respects ocean power may suffer from the same inherent drawbacks as wind power, the variability of renewable power sources.
The proposed harnessing of the Severn estuary raises a further issue that has also bedevilled wind-that implementing the technology can cause great controversy and ironically creates a green dilemma. In the case of the estuary that the means needed to generate the power will fundamentally change the habitat and appearance of the estuary as we know it.
This article concentrates on wave power and examines the current state of the technology and the practical considerations of generating power from this renewable source.