Ocean Wave Energy Current Status and Future Prespectives
The authors of this reference provide an updated and global view on ocean wave energy conversion for wave energy developers as well as for students and professors. The book is orientated to the practical solutions that this new industry has foun
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Stephen Salter School of Engineering and Electronics University of Edinburgh Edinburgh Scotland, UK
‘… if you can hear the truth you’ve spoken twisted by knaves to make a trap for fools …’
In the autumn of 1973 the western economies were given the rare chance of a ride in a time machine and saw what the world would be like when there was no longer cheap oil. Most people thought it looked rather uncomfortable but a few very powerful people made a great deal of money by exaggerating the crisis. Others, who had previously been regarded as eccentric, increased their efforts to develop what were then called alternative, and are now called renewable, energy sources. Still others set out to destroy what they saw to be a threat. Waves were only one of many possible sources and there are many possible ways in which waves can be harnessed. There are floats, flaps, ramps, funnels, cylinders, air-bags and liquid pistons. Devices can be at the surface, the sea bed or anywhere between. They can face backwards, forwards, sideways or obliquely and move in heave, surge, sway, pitch and roll. They can use oil, air, water, steam, gearing or electro-magnetics for generation. They make a range of different demands on attachments to the sea bed and connections of power cables. They have a range of methods to survive extreme conditions but perhaps not quite enough. Their inventors, myself included, invariably claim at first that they are simple and, after experience with the dreadful friction of reality, invariably discover that this is not totally true when they come to test in the correct wave spectra with a Gaussian distribution of wave amplitudes. An easy way to detect beginners is to see if they draw waves the same size on both sides of their device. Appeals to simplicity are widespread and have a strong appeal to non-engineers and particularly to political decision-makers and investors. But it is hard to find any field of technology which does not get steadily more complicated as it gets faster, lighter, cheaper, more powerful and more efficient. The complications are
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2 Looking Back
all introduced for good reasons and, if the necessary hardware is properly researched, will produce good results. Who would abandon railways for wheel barrows because of the smaller number of wheels? Only a simpleton. Although almost everyone knows which of the devices proposed so far will ultimately prove the best it is not certain that no improvement could be invented. This chapter describes some of the work done on several devices at Edinburgh University in the hope that future generations of wave inventors can save time and avoid mistakes.
2.1 Wave Energy at the University of Edinburgh Many inventors of wave power devices, going back to Girard père et fils in 1799, start with heaving floats. Apart from a brief flirtation with oscillating water columns (see Chapters 3 and 7), so did I. But I had the advantage of a workshop in which I could make any mechanical or electronic instrument that I was able to design and there was a narrow tank that
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