Tidal Power

Tide Mills go back to medieval times-the technology is hardly new. Eling near Southampton was working when I was a kid in the '50's.

That is effectivly what the Rance tidal barrage and generator is. Tide comes in, fills the space, shut the gates and let it out through the turbines, electricity produced.

When First Mate worked at AERE Harwell in the '70's a wave system called " Nodding Ducks " was developed. I suspect this is one of the Civil Service cost cuts. It, despite being mechanicaly simple, went no further.

As an aside, a friend-now a late friend-owned substantial Thameside property and a mill dating back to 1400 and something. The Mill had not worked for almost a 100 years, but the Millstream, wheel, sluices and millpool were all there and working.

He tried to get permission to develop a hydropower generator in the mill house. 20 years, no go.

Then the green revolution came, unfortunatly too late for him, but his son got a grant recentlyo do it!
 
DJE said:
Wave power is still being developed.
http://www.emec.org.uk/about-us/wave-clients/pelamis-wave-power/
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In his book, Prof. Makay analyses the potential of wave power using the Pelamis as a basis. He concludes that although, maybe, a possibility for remote island communities, it is unlikely to be able to make a significant contribution to the UK's power needs.
This analysis does not take cost into consideration.
Wave power is really another form of wind power.
 
One of the problems in talking about tidal & wave power is that it is easy to conflate different technologies and approaches, and end up tarring them with the same brush.
There are three main approaches to extracting energy from the sea: wave power (nodding ducks, Pelamis, etc); tidal stream (Meygen, the Strangford Lough turbine, etc), and rise and fall of tide (barrage schemes). All utterly different in nature.
 
Perhaps a fundimental change of strategy is required.
Instead of huge power stations generating electricity for large areas, perhaps smaller local systems using solar, wind or water power might be a different approach.
Malcolm Newell, designer of the ill fated Quasar roofed motorcycle developed a simple 24v lighting system for his streamside home using car alternators driven by a small diameter water wheel supported in the stream by a pair of 5 litre oil containers used as floats. IIRC his main problem-it was all out in the open-was rain making his fan belts slip.
Recycled lorry batteries provided storage. His hot water came from coiled copper tube under glass panels facing South in his garden, pumped to the loft tank by a marine 24v electric pump.

He was incensed that the Electric Board would not remove the mains feed to his house and kept charging him the standing charge even though he used no mains power!
 
Things have moved a lot from then, and with feed in tariff there was the beginnings of a real change towards distributed generation. Unfortunately the tariffs have been cut massively, which threatens to kill off this industry just as it is getting going. I personally know a few people working in the micro generation sector who simply do not know what the future holds. Very hard to run a business in the current climate.

The big game changer over the next couple of decades could be electric vehicles. If people start switching wholesale to EVs, suddenly everyone will have access to a tremendous electricity storage capacity. Most vehicles spend more time sat empty than they do being used, so that is all time in which they are available to be grid connected and acting as a buffer- storing up electricity during sunny or windy weather, or being used as a power source when required.
Smart metering will also help, allowing appliances such as thermal stores to be powered up only during times of grid surplus. With the right combination of technology and price incentives, it should be possible to transition towards a primarily renewable energy system.

Of course it's much easier to throw some money at the French and Chinese and let them build us some nuclear power stations...
 
Kelpie said:
Of course it's much easier to throw some money at the French and Chinese and let them build us some nuclear power stations...
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Absolutely!! Why are we spending zillions giving money to other countries for very expensive 'old style' power stations over a period of half a century (or so?), when the future should be in energy storage from light/tide/wave, whatever it can be, from local generation systems, using technology and engineering developed here, and then sold to the other places!?!?
 
rotrax said:
When First Mate worked at AERE Harwell in the '70's a wave system called " Nodding Ducks " was developed. I suspect this is one of the Civil Service cost cuts. It, despite being mechanicaly simple, went no further.
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Those would have been Salter's Ducks, I expect, developed at Edinburgh University. They were pretty good at getting power from the wave to the float, but it proved impossible to find any remotely practical way to get the power to land. By the time funding was cut they they got to the stage of proposing a gyroscope in each duck, forced precession of which during "nodding" would operate hydraulic pumps sending high pressure fluid to a centralised hydraulic power station. Mechanically simple it was not, and I think the funding cut simply recognised that the technology was a, erm, dead ... you get it.
 
I saw the reference also, and did a bit of background on it. It was a fascinating concept, with HUGE areas of the sea put forward as proposed areas of generation.
Wonderfully British!
 
jamie N said:
Absolutely!! Why are we spending zillions giving money to other countries for very expensive 'old style' power stations over a period of half a century (or so?), when the future should be in energy storage from light/tide/wave, whatever it can be, from local generation systems, using technology and engineering developed here, and then sold to the other places!?!?
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It's storage which is the biggest single problem. The only significant storage in the UK is at Dinorwig and it can keep up 1800MW for 5 hours (9GWh), which is about ten minutes of peak UK electricity demand and sixteen minutes of average demand. There is more than enough tidal power around our coasts to run the country ... but we'd need another fifty Dinorwigs at least to buffer the system.
 
awol said:
Then there's Cruachan with 440MW for 22 hours (9.7GWh) though I don't know if that is inclusive of the National Grid "Black Start" reserve. So that's half an hour of ave. UK demand.
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I didn't think Cruachan had that high a capacity. You may well be right, but according to Wikipedia it has a reservoir capacity of 10,000,000 cubic metres, which over 22 hours would only be 126 cubic metres per second, and Wikipedia says it needs 200 cubic metres per second for full power. Perhaps they start turning turbines off as the available head reduces.

Of course it isn't really half an hour of average UK demand, either. Dinorwig can keep supply 1.8GW/34.4GW = 5.5% for five hours and Cruachan (using the most optimistic figures) can supply 0.4GW/34.4GW = 1.2% for twenty two hours, so the best we have without completely re-engineering is 6.7% for five hours and then 1.2% for seventeen hours.
 
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