ENERGY FROM THE TIDE QUICKLY AND AFFORDABLY

I pointed out in issue 13, some limitations of nuclear energy, In particular the cost of nuclear energy, given the cost of treating (if this ever becomes possible) or of containing and guarding the waste for centuries is very difficult to estimate. How do we estimate the cost of possible misuse of such waste in a “dirty bomb”, decades or centuries from now? How do we price the thousands of deaths resulting from the Chernobyl nuclear accident? (9,000 according to a conservative estimate form the World Health Organisation) How do we estimate the probability of an accident due to human error, such as that which caused the Winscale reactor to overheat?

We have wind farms beginning to appear, consisting of huge towering structures, which dominate the landscape. Offshore wind and wave generators are also being developed. Although the technology is improving rapidly, wind and wave power have serious limitations. The wind does not blow to order, waves are similarly undependable, and in many countries the sun does not shine to order. In contrast tidal energy is much more predictable. The timing and extent of tidal movements of water can be predicted. This means that power generated can be estimated in advance. Also servicing of generation plant can be scheduled for when the tide is out.

A lagoon type structure has been proposed to harness tidal energy in the Severn estuary. Basically the structure would fill up and empty with the tidal movements. The full environmental impact of such a structure needs to be researched in detail, but it seems reasonably likely that appropriately sited and proportioned structures would have no more significant impact on the environment than naturally occurring lagoons. However from what I have seen of plans for such a structure, I'm not sure that the the long term effects are fully understood. Silting takes place over decades and could adversely affect the feasibility of a badly sited structure. More promising is the potential for harnessing the power of tidal movement using the tidal wall principle. These so called walls consist of submerged turbines in places with strong tidal flow.

I believe there is considerable potential for the adaptation of existing structures such as bridges, quays, jetties and other installations for the harnessing of tidal energy. Many such structures have been in place for decades and by now we should have some understanding of their environmental impact. There are many quays and jetties which are no longer used for their original purposes, as coastal industries have declined.

Thirty years ago, I developed a floating generator with turbines which turned with the movement of water beneath a floating structure, which would rise and fall with the level of the tide. Such generators could be attached to existing structures with appropriate consideration for safety and environmental impact. This would provide relatively affordable energy by considerably reducing construction costs. Suitable structures tend to be sited near centres of population so transmission and maintenance costs would be low.

Tidal energy has an important part to play alongside other energy sources, such as locally produced bio-energy crops, in supplying safe and affordable power, relatively quickly, as part or a responsible energy strategy.

Tidal energy is the obvious choice for powering desalination equipment, which requires mechanical energy to enforce the osmotic process and water flow. This mechanical energy is directly available from moving water, without the need for conversion to electrical energy. Any electricity required for the process can of course be generated on site reducing the cost and inconvenience of transmission.

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