Potential for tidal power generation? Sailors thoughts.

[Tranona]

I seem to recall, but may be mistaken, that there was once a small tide mill of the latter kind on the Rance itself.

May well have been. Before the advent of steam power, water was the most common form of power for mills - either running water from streams/rivers of tidal with water held behind a dam controlled by sluices and released when required.

There have been a number of schemes using barrages proposed for the Bristol Channel and South Wales but AFAIK they have all been rejected on various grounds, mainly economic. This seems somewhat odd given that wind farms are approved despite also being uneconomic and unsightly.

 

[zoidberg]

There have been a number of schemes using barrages proposed for the Bristol Channel and South Wales

I seem to recall the suggestion that a tidal barrage for hydro-electricity be built across the Western Solent at Hurst. This would seem to have some merits.....

 

[sarabande]

I understand from a brother who lives in France that the Rance barrage is silting up* as the dynamics of the estuary are constrained by the structure. There are significant negative influences on marine wildlife which are only now becoming apparent, e.g. flatties and sandeels.


*
A similar fate is affecting the Aswan dam.

 

[Hydrozoan]

May well have been. Before the advent of steam power, water was the most common form of power for mills - either running water from streams/rivers of tidal with water held behind a dam controlled by sluices and released when required.

There have been a number of schemes using barrages proposed for the Bristol Channel and South Wales but AFAIK they have all been rejected on various grounds, mainly economic. This seems somewhat odd given that wind farms are approved despite also being uneconomic and unsightly.

Yes, I was tangentially involved for a while with studies on the Severn. No, it would not be surprising to find an old tidal mill on the Rance and not only do I seem to recall a Breton friend pointing out one as we drove past, but a quick search has picked up three!

 

[Boathook]

Well Scotland has now had several days on which 100% of our energy needs were met by renewables. So it sounds as though there is lots of renewable energy up here, if conditions are right.

That's the problem - if conditions are right. A dull windless day will mean very little production of leccy so back up is required. What the back up is anyone's guess / views.
This is a good site to show how power is being produced.
http://www.gridwatch.templar.co.uk/index.php

 

[penberth3]

Just a thought - anyone who has been to Bembridge will have seen, and probably walked along, the sea wall enclosing the pound for a tide mill.
Would it be cost effective to harness the tide power available here?...

If it was cost effective somebody would have done it. The subsidies were skewed towards wind and solar so that's what was built, hydro got very little.

 

[Tranona]

Yes, I was tangentially involved for a while with studies on the Severn. No, it would not be surprising to find an old tidal mill on the Rance and not only do I seem to recall a Breton friend pointing out one as we drove past, but a quick search has picked up three!

Suspect that Plouer would have been one. What is now the marina basin looks like a mill pond.

 

[A1Sailor]

You wonder why the Thames Barrage didn't have a turbine built into it, with locks of varying sizes in the centre for shipping. Too much disruption to navigation I guess, or inadequate flow.

 

[Hydrozoan]

Suspect that Plouer would have been one. What is now the marina basin looks like a mill pond.

Yes Plouer is one - and it looks like the one I vaguely recall. One of the others has been converted into a house.

 

[A1Sailor]

Well Scotland has now had several days on which 100% of our energy needs were met by renewables. So it sounds as though there is lots of renewable energy up here, if conditions are right.

That's the problem - if conditions are right. A dull windless day will mean very little production of leccy so back up is required. What the back up is anyone's guess / views.
This is a good site to show how power is being produced.
http://www.gridwatch.templar.co.uk/index.php

On dull windless days, Scotland has sufficient power generation from Hydro, Gas & Nuclear to almost meet its needs. Most days Scotland is an exporter of electricity.
Very roughly 5x20% of Scotland's power generation is from hydro, gas(1), nuclear(2) and wind. Approximately 20% of the 5-6TWh generated is surplus to requirements - as long as nothing breaks down, including the wind!
http://www.ybw.com/forums/showthread.php?492417-Scotland-s-lecky
The site at Boathook's link is excellent - but there doesn't seem to be an equivalent for Scotland.

Edit:
There's some "regional" info here:https://www.solar.sheffield.ac.uk/pvlive/regional/
but I can't work it out and/or can't be bothered!

 

[wotayottie]

Hi guys and gals,

I was talking about this with a friend and colleague earlier. I guess figuring out all the numbers-logistics would take a long time (must be a PHD in there for someone), but given the UK's huge tides we could surely generate most of our energy needs with just tide?

Obviously the downside would be the huge amount of energy expended on such a massive project, inconvenience to sailors and shipping and other costs I haven't even thought about.

On the whole it would make sense though. Massive investment in self sufficiency, skills, infrastructure. It certainly beats dirty coal and expensive nuclear power.

Numbers? Thoughts? Given that Bristol channel has one of the highest tidal ranges in the world the potential for turning that into clean energy must be tremendous.

Cheers, Keef

They keep looking at a barrage for the bristol channel but the costs of it make nukes look cheap. As a sailor, a barrage wouldnt bother me - I cant leave my mooring without going through a lock as it is and in Swansea you have to go through two locks to get to the marina.

 

[solent clown]

the other side of the coin is the lack of effective large scale energy storage, My little renewables prediction for the future is the development of large scale viable gravity batteries to smooth the grid as renewables increase yield, but remain relatively erratic and not adaptable enough to cope with peak demand.
Just you watch and see.

 

[Kelpie]

... wind farms are approved despite also being uneconomic and unsightly.

Uneconomic by what measure? It is widely reported that onshore wind is now the cheapest form of generation.

 

[NormanS]

the other side of the coin is the lack of effective large scale energy storage, My little renewables prediction for the future is the development of large scale viable gravity batteries to smooth the grid as renewables increase yield, but remain relatively erratic and not adaptable enough to cope with peak demand.
Just you watch and see.

Pumped storage hydro is just that. Check out Cruachan.

 

[A1Sailor]

Pumped storage hydro is just that. Check out Cruachan.

Yup. Dinorwig, Ffestiniog (both in Wales) and Foyers are the others in UK.
https://en.wikipedia.org/wiki/Hydro...ist_of_UK_hydroelectric_schemes_over_1,000_kW

 

[solent clown]

there will be a huge proliferation of gravity storage if the powers that be think long term, batteries are all very well but the resources are finite.

 

[A1Sailor]

I've got a 30kWh car battery I can currently charge at no cost. If the powers that be want me to do it overnight I'll do it, if they pay me!

 

[Tranona]

Uneconomic by what measure? It is widely reported that onshore wind is now the cheapest form of generation.

They are only "economic" because of the subsidy given to build them and the higher price paid for their output - all courtesy of our inflated energy bills. Doing the calculations that way shows a "profit" for the operator. Also of course, no charge for the impact on the environment nor of the disposal cost when policy or technological changes in the future require them to be removed.

I might live long enough for wind energy to be shown as one of the worst policy decisions of all time. Not that I am biased of course!

 

[earlybird]

It is widely reported that onshore wind is now the cheapest form of generation.

That claim, AFAIK, was based on a cost for a wind installation yet to be built, and may well never be.
The Advertising Standards Authority has apparently required adverts making that claim not to be repeated.
In reality, wind-power costs can be and are several times the market price despite having a privileged position in the market.

 

[Kelpie]

They are only "economic" because of the subsidy given to build them and the higher price paid for their output - all courtesy of our inflated energy bills. Doing the calculations that way shows a "profit" for the operator. Also of course, no charge for the impact on the environment nor of the disposal cost when policy or technological changes in the future require them to be removed.

I might live long enough for wind energy to be shown as one of the worst policy decisions of all time. Not that I am biased of course!

It's a bit tricky to get proper figures on this. All forms of energy appear to be subsidised whether directly or not, and not all measures of cost include things like end of life removal, ongoing fuel costs, or carbon taxes (which btw cannot be ignored unless you propose abandoning our various climate change commitments).

One thing that is obvious, though, is the direction of travel. Fossil fuel wholesale prices and carbon levies are likely to rise, and renewables are demonstrably falling in price with each passing year. Subsidies for renewables are now a fraction of what they were even five years ago, yet new schemes continue to be built.

It's obviously not all rosy, of course. We're going to have to get used to thinking about our electricity in a different way, with smart meters/appliances taking advantage of excess production, and electric vehicles becoming a key part of the storage infrastructure.

You'll probably call this source biased but it's about as detailed a description as I've found on the question of wind vs gas production costs: https://www.carbonbrief.org/analysis-uk-auction-offshore-wind-cheaper-than-new-gas