Donate to Remove ads

Got a credit card? use our Credit Card & Finance Calculators

Thanks to johnstevens77,Bhoddhisatva,scotia,Anonymous,Cornytiv34, for Donating to support the site

Tidal turbine

Scientific discovery and discussion
scotia
Lemon Quarter
Posts: 3561
Joined: November 4th, 2016, 8:43 pm
Has thanked: 2371 times
Been thanked: 1943 times

Re: Tidal turbine

#161388

Postby scotia » August 23rd, 2018, 1:42 am

Slarti wrote:
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

That is an excellent point. At one time we held a considerable lead in the construction of nuclear power stations. It is true that their were some costly learning curves - e.g. Dungeness, however the early Magnox and the majority of the later AGR reactors of British design and construction have provided safe, reliable and cost effective electricity power generation. However for various socio-political reasons, we ceased their construction, and all British expertise in this field was dissipated. Now we realise that such generation is a necessity, and we are having to pay the price to foreign countries who have developed their own expertise.
I'm acutely aware of how high this cost is. Part of it is due to the decision to require the foreign consortia to raise their own loans at commercial rates, rather than to use government borrowing which can be achieved at much lower rates. I believe that part of the rationale behind this appears to be that the government want to distance themselves from possible cost over-runs.
If we had retained our own design teams, and had continued to build (government-funded) incremental improvements on our own working designs then we would not be paying such extortionate sums.
So why do we believe it is necessary to go ahead with expensive Nuclear Generation as part of a Sustainable Energy mix? I think the best published study of this area is "Sustainable Energy - without the hot air" by the late David JC Mackay (professor of Physics, Cambridge) (http://www.withouthotair.com)

scotia
Lemon Quarter
Posts: 3561
Joined: November 4th, 2016, 8:43 pm
Has thanked: 2371 times
Been thanked: 1943 times

Re: Tidal turbine

#161390

Postby scotia » August 23rd, 2018, 2:25 am

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

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

Why would you need to seal it up for 10 thousand years? We don't see the need to seal up Orkney or South West England, where there is substantially more radioactivity with a much longer half life than your feared waste from nuclear power stations.
I assume you have a smoke detector in your home, which uses a radioactive source. Are you going to seal it up and store it underground for 10 thousand years?
The glassification proposals are simply a convenient way of parcelling up the small fraction of the most highly radioactive components in nuclear waste into a small volume. Even if the radio active components migrated out of the glass (unlikely) into the storage chamber, it really wouldn't matter, since it is extremely unlikely to be anywhere near peoples' homes - in contrast to the significant amounts of naturally occurring radioactivity which is present immediately underneath a substantial number of homes in certain areas of the UK.

jackdaww
Lemon Quarter
Posts: 2081
Joined: November 4th, 2016, 11:53 am
Has thanked: 3203 times
Been thanked: 417 times

Re: Tidal turbine

#161411

Postby jackdaww » August 23rd, 2018, 8:25 am

scotia wrote:
jackdaww wrote:
scotia wrote: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, ......


=============================

what is a fission reactor please ? do we have any ?

GoSeigen
Lemon Quarter
Posts: 4349
Joined: November 8th, 2016, 11:14 pm
Has thanked: 1590 times
Been thanked: 1579 times

Re: Tidal turbine

#161432

Postby GoSeigen » August 23rd, 2018, 10:20 am

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

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


LOL. We had NO EXPERIENCE of using wheels before they were invented. Still managed that okay.

Lack of experience seems a poor excuse for not attempting something.


Quite apart from the fact that the Egyptians sealed things up pretty satisfactorily for five thousand years, which is not that different to ten thousand. But hey, they were just Arabs, I guess their experience doesn't count...

;-)

GS

scotia
Lemon Quarter
Posts: 3561
Joined: November 4th, 2016, 8:43 pm
Has thanked: 2371 times
Been thanked: 1943 times

Re: Tidal turbine

#161453

Postby scotia » August 23rd, 2018, 11:39 am

what is a fission reactor please ? do we have any ?

All of our Nuclear Power Stations provide their power from Nuclear Fission - i.e. they are fission reactors.
The great hope (which has been a hope for more than half a century) is that we may eventually obtain power from Nuclear Fusion - by joining together two isotopes of Hydrogen. This would provide power without generating radioactive fission products. However a practical Fusion reactor has not yet been made to operate. The Joint European Torus (JET) at Culham was the world's largest experimental fusion research facility when constructed around 1985. It is currently being used to test a number of features of the proposed International Thermonuclear Experimental Reactor (ITER) which will be built in France - completion date around 2025. But I should stress that this mega-project will not produce sufficient power for net electrical production - it is still "experimental".

jackdaww
Lemon Quarter
Posts: 2081
Joined: November 4th, 2016, 11:53 am
Has thanked: 3203 times
Been thanked: 417 times

Re: Tidal turbine

#161475

Postby jackdaww » August 23rd, 2018, 1:10 pm

scotia wrote:
jackdaww wrote:
scotia wrote: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. ?


=======

my mistake , i misread fission for fusion .

but my understanding is that the breakdown/split in the reactor produce isotopes with LONGER half lives . i dont know where i got that from - can anyone shed more light on that ?

9873210
Lemon Slice
Posts: 984
Joined: December 9th, 2016, 6:44 am
Has thanked: 226 times
Been thanked: 296 times

Re: Tidal turbine

#161485

Postby 9873210 » August 23rd, 2018, 1:44 pm

scotia wrote:
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?


The Tc99 in the waste has a yield of about 6% and a half life of 200,000 years. Ignore every other isotope and the claim is still false.

The idea of background radiation level in thousands of year (with implications of safe after 50 years) is as far off as the idea of absolutely deadly forever.

For every complex problem there is an answer that is clear, simple, and wrong.

scotia
Lemon Quarter
Posts: 3561
Joined: November 4th, 2016, 8:43 pm
Has thanked: 2371 times
Been thanked: 1943 times

Re: Tidal turbine

#161494

Postby scotia » August 23rd, 2018, 2:22 pm

9873210 wrote:
scotia wrote:
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?


The Tc99 in the waste has a yield of about 6% and a half life of 200,000 years. Ignore every other isotope and the claim is still false.

The idea of background radiation level in thousands of year (with implications of safe after 50 years) is as far off as the idea of absolutely deadly forever.

For every complex problem there is an answer that is clear, simple, and wrong.


I'm a bit confused by your analysis. Uranium 235 has a half life of 703,8000,000 years. Technetium 99 occurs in about 6% of U235 thermal neutron fissions in a conventional nuclear reactor. It has a half life of 211,000 years. So if I follow your advice to ignore all other isotopes I cannot possibly see how you imagine the claim is false (unless you think it is less than 50 years).
And incidentally, the weak Beta radiation from TC99 would be stopped by a glass jar.

scotia
Lemon Quarter
Posts: 3561
Joined: November 4th, 2016, 8:43 pm
Has thanked: 2371 times
Been thanked: 1943 times

Re: Tidal turbine

#161533

Postby scotia » August 23rd, 2018, 4:58 pm

OK - In my previous response I confessed that I was puzzled by the Tc99 response (of 9873210). Its a weak Beta emitter and I think the UK used to simply offload it into the Irish Sea! Thinking it over, I suspect that the discussion of the radiation emitted by Tc99 involved the number of disintegrations (single beta decays) per unit of time of Tc99 versus the number of U235 disintegrations (multiple Alpha, Beta and Gamma decays) per unit of time.
So to clear up any confusion I may have caused, If we look at the contained high level waste from nuclear power stations, then It is generally observed that the decay time to reach the same level of radioactivity as its original parent, is in the time scale I mentioned. I would welcome correction from any contrary published evidence. And yes - I fully understand the difficulties in defining the measure of human-harmful radioactivity in its several forms and many energy levels. Without wishing to teach grandmother to suck eggs, could I point out that Alpha particles can be stopped by a sheet of paper, Beta particles by a few millimetres of aluminium, but it is the Gamma rays from nuclear waste that require metres of concrete to stop them.

Howard
Lemon Quarter
Posts: 2178
Joined: November 4th, 2016, 8:26 pm
Has thanked: 885 times
Been thanked: 1017 times

Re: Tidal turbine

#161541

Postby Howard » August 23rd, 2018, 5:42 pm

A really interesting thread.

Going back to the OP and following GoSeigen’s post I checked the output of Sizewell B. I believe it produces about 3,000 times the electricity of the wave machine. And continuously.

So this suggests that to produce the output of one nuclear power station would require at least 3,000 wave machines round the UK.

As a complete layman in these matters I’m interested in comments as to whether they would cause some significant environmental issues. Possibly changing tidal patterns and causing silting issues.

The construction, mapping and maintenance of 3,000 machines would certainly create a lot of employment!

regards

Howard

jfgw
Lemon Quarter
Posts: 2539
Joined: November 4th, 2016, 3:36 pm
Has thanked: 1097 times
Been thanked: 1146 times

Re: Tidal turbine

#161562

Postby jfgw » August 23rd, 2018, 6:33 pm

Other questions regarding tidal generators: How much energy do they take to manufacture, maintain and salvage and how much energy do they produce during their lifetimes?

Are they harmful to wildlife?

I would be very surprised if they had a detectable effect on tidal patterns; you would need a pretty impressive dam to do that!


Julian F. G. W.

Sorcery
Lemon Quarter
Posts: 1229
Joined: November 4th, 2016, 6:38 pm
Has thanked: 147 times
Been thanked: 366 times

Re: Tidal turbine

#161567

Postby Sorcery » August 23rd, 2018, 7:01 pm

scotia wrote:
Slarti wrote:
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

That is an excellent point. At one time we held a considerable lead in the construction of nuclear power stations. It is true that their were some costly learning curves - e.g. Dungeness, however the early Magnox and the majority of the later AGR reactors of British design and construction have provided safe, reliable and cost effective electricity power generation. However for various socio-political reasons, we ceased their construction, and all British expertise in this field was dissipated. Now we realise that such generation is a necessity, and we are having to pay the price to foreign countries who have developed their own expertise.
I'm acutely aware of how high this cost is. Part of it is due to the decision to require the foreign consortia to raise their own loans at commercial rates, rather than to use government borrowing which can be achieved at much lower rates. I believe that part of the rationale behind this appears to be that the government want to distance themselves from possible cost over-runs.
If we had retained our own design teams, and had continued to build (government-funded) incremental improvements on our own working designs then we would not be paying such extortionate sums.
So why do we believe it is necessary to go ahead with expensive Nuclear Generation as part of a Sustainable Energy mix? I think the best published study of this area is "Sustainable Energy - without the hot air" by the late David JC Mackay (professor of Physics, Cambridge) (http://www.withouthotair.com)


While this is true, there seems to have been massive building cost inflation for nuclear power since the late 60s mainly because of fear of nuclear and likely the over tightening of safety standards.

Here is a graph of costs per kilowatt x axis against cumulative installed capacity.
https://curryja.files.wordpress.com/201 ... -59-pm.png

Graph shamelessly nicked from an article by Peter Lang here https://judithcurry.com/2017/12/21/forg ... ate-1960s/

Slarti
Lemon Quarter
Posts: 2941
Joined: November 4th, 2016, 3:46 pm
Has thanked: 640 times
Been thanked: 496 times

Re: Tidal turbine

#161740

Postby Slarti » August 24th, 2018, 11:25 am

scotia wrote:
Slarti wrote:
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

That is an excellent point. At one time we held a considerable lead in the construction of nuclear power stations. It is true that their were some costly learning curves - e.g. Dungeness, however the early Magnox and the majority of the later AGR reactors of British design and construction have provided safe, reliable and cost effective electricity power generation. However for various socio-political reasons, we ceased their construction, and all British expertise in this field was dissipated. Now we realise that such generation is a necessity


I would argue that nobody knows what the true cost of nuclear energy is.

Bradwell power station has been "decommissioned" but it is still there as a blot on the landscape and will be for another couple of hundred years, as far as I know
Image

But the costs incurred by the Nuclear Decommissioning Authority, and still to incurred, don't seem to be part of the accounting for the cost of nuclear fuel. I wonder why not?


And, given the way solar, wind and storage are coming along, is nuclear really a necessity? If all that money were to be put into renewables and storage, I suspect that we, as a nation, would be much better off.

Slarti

Slarti
Lemon Quarter
Posts: 2941
Joined: November 4th, 2016, 3:46 pm
Has thanked: 640 times
Been thanked: 496 times

Re: Tidal turbine

#161743

Postby Slarti » August 24th, 2018, 11:32 am

Howard wrote:So this suggests that to produce the output of one nuclear power station would require at least 3,000 wave machines round the UK.

As a complete layman in these matters I’m interested in comments as to whether they would cause some significant environmental issues. Possibly changing tidal patterns and causing silting issues.

The construction, mapping and maintenance of 3,000 machines would certainly create a lot of employment!


It would only require 3000 if there was no development of the technology. Wind turbines have greatly increased in capacity since the first ones were installed, more than double, I believe. I would expect these to go the same way.

Slarti

Watis
Lemon Quarter
Posts: 1403
Joined: November 5th, 2016, 10:53 am
Has thanked: 352 times
Been thanked: 489 times

Re: Tidal turbine

#161757

Postby Watis » August 24th, 2018, 12:20 pm

Slarti wrote:
I would argue that nobody knows what the true cost of nuclear energy is.

Bradwell power station has been "decommissioned" but it is still there as a blot on the landscape and will be for another couple of hundred years, as far as I know
Image

But the costs incurred by the Nuclear Decommissioning Authority, and still to incurred, don't seem to be part of the accounting for the cost of nuclear fuel. I wonder why not?


And, given the way solar, wind and storage are coming along, is nuclear really a necessity? If all that money were to be put into renewables and storage, I suspect that we, as a nation, would be much better off.

Slarti


A blot on the landscape today.

A Grade 1 listed building tomorrow!

Watis

tea42
Lemon Slice
Posts: 440
Joined: March 9th, 2017, 8:28 am
Has thanked: 77 times
Been thanked: 169 times

Re: Tidal turbine

#161762

Postby tea42 » August 24th, 2018, 12:26 pm

Snorvey wrote:It would only require 3000 if there was no development of the technology. Wind turbines have greatly increased in capacity since the first ones were installed, more than double, I believe. I would expect these to go the same way.

Definitely. This is an early stage prototype machine - I think it's got plenty of development from here.

I think the point is that these are relatively simple machines and could be built on automotive style production lines. I would reckon 3000 could be built almost as quickly as it takes, say, Scania to build 3000 lorries or Denis to build 3000 buses.

Then all you have to do is tow it out to your preferred location, plug it in and anchor it to the seabed. The oil industry has been doing just that for decades. Keep a few spare machines onshore for easy swapovers and you have cheap, limitless, reliable energy for as long as the moon orbits the Earth.


Unfortunately that is all beyond the wit of polictricians because there are very few Engineers in Parliament . Many would suffer angst at tbe thought of Tidal Flow generators chopping up fishy wishys. Caroline Lucas would have apoplexy and Vince Cable would lobby for a Referendum.

Bring in Xi Jinping I say…

kiloran
Lemon Quarter
Posts: 4092
Joined: November 4th, 2016, 9:24 am
Has thanked: 3234 times
Been thanked: 2827 times

Re: Tidal turbine

#161765

Postby kiloran » August 24th, 2018, 12:30 pm

Snorvey wrote:[i] and you have cheap, limitless, reliable energy for as long as the moon orbits the Earth.

[pedant mode]
It's more about the earth spinning, in the presence of a moon
[/pedant mode]

--kiloran

tjh290633
Lemon Half
Posts: 8208
Joined: November 4th, 2016, 11:20 am
Has thanked: 913 times
Been thanked: 4096 times

Re: Tidal turbine

#161801

Postby tjh290633 » August 24th, 2018, 1:58 pm

Going back 20 years or so, someone had a project to harness estuarial and inlet tidal flow power with a simple container-based turbine. It failed to get sufficient backing, but it struck me at the time as a very realistic approach. It used a turbine on a vertical axis, and since there was little or no differential speed between water and turbine blades, there should be minimal danger to aquatic life.

Low cost, low impact and low maintenance.

TJH

scotia
Lemon Quarter
Posts: 3561
Joined: November 4th, 2016, 8:43 pm
Has thanked: 2371 times
Been thanked: 1943 times

Re: Tidal turbine

#161810

Postby scotia » August 24th, 2018, 2:14 pm

FredBloggs wrote: They do all sorts of clever things so the poor little things can swim right past those horrid turbiney things.

Slightly deviating from the subject - Hydro Engineers have long experience of looking after not-so-small fishy wishes.
To allow salmon to circumvent the dam and its turbines they have constructed fish ladders - and at least on one Scottish Hydro plant they have a fish lift.

scotia
Lemon Quarter
Posts: 3561
Joined: November 4th, 2016, 8:43 pm
Has thanked: 2371 times
Been thanked: 1943 times

Re: Tidal turbine

#161812

Postby scotia » August 24th, 2018, 2:26 pm

Slarti wrote:Bradwell power station has been "decommissioned" but it is still there as a blot on the landscape and will be for another couple of hundred years, as far as I know
Slarti

I didn't find the buildings in your picture a "blot" - or at least they seem considerably less of a blot than the buildings currently being constructed all over London, and a lot less of a blot than several hundred wind turbines on the site. How about swapping them for some coal bings (still burning) up here in Scotland?


Return to “Science”

Who is online

Users browsing this forum: No registered users and 6 guests