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Tidal turbine

Scientific discovery and discussion
jackdaww
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Re: Tidal turbine

#161089

Postby jackdaww » August 21st, 2018, 6:48 pm

where does the steam come from ?

Itsallaguess
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Re: Tidal turbine

#161094

Postby Itsallaguess » August 21st, 2018, 7:36 pm

jackdaww wrote:
where does the steam come from ?


I think it's the developers ears whenever someone mentions the word 'subsidies'.....

Nice technology though - I think we should be doing more in this area, what with all the water any everything....

Cheers,

Itsallaguess

tjh290633
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Re: Tidal turbine

#161104

Postby tjh290633 » August 21st, 2018, 8:50 pm

Probably "Tidal Stream". Ever since they held the first trials in the Bristol Channel I've been convinced that this is the way to go. No barriers or disruptive construction. Powered by the gravitational pull of the sun and the moon. How greener can you get?

TJH

GoSeigen
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Re: Tidal turbine

#161138

Postby GoSeigen » August 21st, 2018, 11:41 pm

It's a miracle. It produces 7% of the power needs of a population of 20,000. Great! That's enough for my village then. What about the other 69,998,600 people who live in the UK?

Sizewell alone outputs more energy overnight than this project has generated in its year of existence.

Bit of work to do still, I think...


GS

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Re: Tidal turbine

#161155

Postby jfgw » August 22nd, 2018, 7:23 am

How useful is this tidal energy? We could power the whole of the UK with enough of these (we would need a lot) but we would have four power cuts per day.

Julian F. G. W.

kiloran
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Re: Tidal turbine

#161171

Postby kiloran » August 22nd, 2018, 9:17 am

jfgw wrote:How useful is this tidal energy? We could power the whole of the UK with enough of these (we would need a lot) but we would have four power cuts per day.

Julian F. G. W.

Would we have four power cuts? The time of the tides varies greatly around the UK, so some/most turbines would be operational while some are inactive as the tide turns.

--kiloran

jackdaww
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Re: Tidal turbine

#161177

Postby jackdaww » August 22nd, 2018, 9:36 am

many years ago there was a system of "floating ducks" .

maybe this is the latest development from that .

could be part of a mix of of sources producing power at different times during the time/weather cycle ?

could still have a few coal/gas stations running continuously providing base power .

could use gas turbines for flexible backup power when renewables not producing .

ANYTHING but nuclear , the waste from which has a half life of 10000 years. ( yes -- ten thousand) .

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Re: Tidal turbine

#161184

Postby tea42 » August 22nd, 2018, 10:08 am

jfgw wrote:How useful is this tidal energy? We could power the whole of the UK with enough of these (we would need a lot) but we would have four power cuts per day.

Julian F. G. W.


If the tidal turbines were placed at various headlands and sites like the Swynge Alderney, The Severn estuary and Orkney we would get continuous totally predictable tidal power. High tidal flows occur at vastly different times all around our coastline. A great source of green power studiously ignored by polictricians for decades. There would be no power cuts from this source especially in contrast to solar sources which die at night and wind and wave power which stop when the wind dies like in January when its freezing in High Pressure episodes.

kiloran
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Re: Tidal turbine

#161197

Postby kiloran » August 22nd, 2018, 11:19 am

jackdaww wrote:many years ago there was a system of "floating ducks" .

maybe this is the latest development from that .

My understanding is that the floating ducks use wave power, whereas this turbine uses tidal flow

--kiloran

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Re: Tidal turbine

#161209

Postby tea42 » August 22nd, 2018, 12:15 pm

I knew Professor Salter, the Achilles Heel of such devices as the Ducks was the likelyhood of violent storms. To make Ducks that can resist such events is very difficult. Wind turbines can be stopped and the blades feathered. Wave energy is determined by wind which we all know is unpredictable. We could have been world leaders in tidal energy with a bit of vision from the money men and polictricians, but as usual we are missing a technological opportunity to harness the power of nature.

A University wanted to try their turbine device in the Hurst Narrows in the Solent. After years of wrangling with various bodies they gave up and went to Iceland instead. The Minister responsible made a positive decision on the spot.

scotia
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Re: Tidal turbine

#161303

Postby scotia » August 22nd, 2018, 6:45 pm

jackdaww wrote:
ANYTHING but nuclear , the waste from which has a half life of 10000 years. ( yes -- ten thousand) .

The nuclear fuel is radioactive, with a much longer half life than the waste. Depending on the reactor fuel type and burn, the waste may be less radio active than the fuel after 50 to 1000 years.
Uranium (the nuclear fuel) occurs naturally in the soil. In particular areas (e.g. in the South West) where the concentration is high, venting of the radioactive gas radon from under your house may be advisable. Yet no one seems to worry about this. However if anything like these levels of natural radioactivity are present in any form of "nuclear waste" then people seem to imagine that they need cast iron protection from it for millennia.
Hysteria seems to surround the word "nuclear". A frequently employed health check uses the technique of Nuclear Magnetic Resonance, or NMR as it is known in the scientific community. But the medical profession describe it as MRI - Magnetic Resonance Imaging - dropping out the key word.
And incidentally Coal, Gas and Oil burning power stations freely emit radioactivity from burning the fuel. No attempt is made to capture it!
I welcome the attempt to generate tidal power, but I suspect it has a long way to go before it can be an economic solution.
In the meantime, vast arrays of towers are being built around our coasts to provide wind power. I wonder who will fund the dismantling of these at the end of their useful life.

jackdaww
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Re: Tidal turbine

#161309

Postby jackdaww » August 22nd, 2018, 6:55 pm

scotia wrote:
jackdaww wrote:
ANYTHING but nuclear , the waste from which has a half life of 10000 years. ( yes -- ten thousand) .

The nuclear fuel is radioactive, with a much longer half life than the waste. Depending on the reactor fuel type and burn, the waste may be less radio active than the fuel after 50 to 1000 years.

.


======

ok good .

so what happens to this nuclear fuel in the reactor , what is the half life of the reactors products ?

Sorcery
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Re: Tidal turbine

#161321

Postby Sorcery » August 22nd, 2018, 7:46 pm

jackdaww wrote:
scotia wrote:
jackdaww wrote:
ANYTHING but nuclear , the waste from which has a half life of 10000 years. ( yes -- ten thousand) .

The nuclear fuel is radioactive, with a much longer half life than the waste. Depending on the reactor fuel type and burn, the waste may be less radio active than the fuel after 50 to 1000 years.

.


======

ok good .

so what happens to this nuclear fuel in the reactor , what is the half life of the reactors products ?


Does it really matter what the half life is? The "problem" of nuclear waste can be solved by diluting it in molten glass to say the radioactive levels of Uranium ore or Thorium ore (both naturally occurring) and either putting it down a mine or as James Lovelock suggested dumping it in a national park where the animals don't care and it might keep the people out :-)

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Re: Tidal turbine

#161324

Postby Slarti » August 22nd, 2018, 7:54 pm

jfgw wrote:How useful is this tidal energy? We could power the whole of the UK with enough of these (we would need a lot) but we would have four power cuts per day.


You do know that high/low tides occur at different times of the day in different places?

Eg tonight high tides
Lowestoft 19:31
Harwich 21:13
Clacton 21:25
Brightlingsea 21:37
Burnham-on-Crouch 22:02

So a 30 minute spread along a short stretch of coast.

Cover the whole country and 4 power cuts per day will not happen.

Slarti

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Re: Tidal turbine

#161329

Postby Slarti » August 22nd, 2018, 8:06 pm

scotia wrote:In the meantime, vast arrays of towers are being built around our coasts to provide wind power. I wonder who will fund the dismantling of these at the end of their useful life.


Remind me, how long is the useful life of a wind turbine, compared to the time to remove the remains of a nuclear power station?

Local to me is Bradwell Power Station which has now nearly been completely decommissioned and encased in concrete(?)
Apparently this eyesore will be there for at least 200 years, before it is safe to remove.

There are wind turbines between it and the A414 that are not visible at the range of the power station.

Oh, and despite near universal opposition of people living in the area, we are going to be treated to another :x


Slarti

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Re: Tidal turbine

#161330

Postby Slarti » August 22nd, 2018, 8:09 pm

scotia wrote:I welcome the attempt to generate tidal power, but I suspect it has a long way to go before it can be an economic solution.


You think that nuke is an economic solution?


Remind me, what are they promising the Chinese per KWH for Hinkley Point II?

And how much is offshore wind or solar per KWH, today?


Slarti

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Re: Tidal turbine

#161344

Postby 9873210 » August 22nd, 2018, 9:14 pm

Sorcery wrote:Does it really matter what the half life is? The "problem" of nuclear waste can be solved by diluting it in molten glass to say the radioactive levels of Uranium ore or Thorium ore (both naturally occurring) and either putting it down a mine or as James Lovelock suggested dumping it in a national park where the animals don't care and it might keep the people out :-)


The half life determines the dilution needed.

A half life of, say, a year would require a dilution by a factor of billions. Dumping cubic kilometres of glass would get the attention of any animals. But you could let that decay for a few decades before vitrifying it. Perhaps pump some water round it to generate useful steam.

But there’s a problem with a half life of tens to thousands of years. These require either inconveniently high dilution or inconveniently long cooling periods.

jackdaww
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Re: Tidal turbine

#161354

Postby jackdaww » August 22nd, 2018, 9:53 pm

there is yet another elephant in the room .

we have NO EXPERIENCE of sealing stuff up for ten thousand years .

tjh290633
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Re: Tidal turbine

#161381

Postby tjh290633 » August 22nd, 2018, 11:02 pm

jackdaww wrote:there is yet another elephant in the room .

we have NO EXPERIENCE of sealing stuff up for ten thousand years .


That which is naturally in the earth has been there for a few million years or so, decaying all the time.

The techique does not involve sealing it up, it uses encapsulation in a suitably formulated glass which may be then in a sealed container, but the durability of the glass means that the radioactive components are securely held for a long time.

Remember the Trimphone? The dials were slightly radioactive to provide the luminescence. They had to be treated as nuclear waste.

TJH

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Re: Tidal turbine

#161384

Postby scotia » August 23rd, 2018, 12:58 am

jackdaww wrote:
scotia wrote:
jackdaww wrote:
ANYTHING but nuclear , the waste from which has a half life of 10000 years. ( yes -- ten thousand) .

The nuclear fuel is radioactive, with a much longer half life than the waste. Depending on the reactor fuel type and burn, the waste may be less radio active than the fuel after 50 to 1000 years.

.


======

ok good .

so what happens to this nuclear fuel in the reactor , what is the half life of the reactors products ?


Perhaps I didn't make myself clear. In a fission reactor, the nuclear fuel (Uranium) is split into a number of lighter elements which are generally radioactive, but with half lives considerably less than the Uranium fuel. Now if you plot the radioactivity against time of the Uranium fuel as originally loaded into the reactor, and if you also plot a similar graph of the used nuclear fuel (often referred to as nuclear waste), then the nuclear waste graph will start considerably higher than the original fuel graph, but it will fall much more rapidly than the original fuel graph, with the crossing point typically occurring between 50 to 1000 years, depending on the fuel type and burn. So if we are not worried about the radioactivity of the original Uranium fuel, why should we be concerned about the lesser radioactivity of the "nuclear waste" thousands of years after its production?


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