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Topic Title: Tidal Power
Topic Summary: Is it realistic?
Created On: 19 October 2012 11:31 AM
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 29 November 2012 03:27 PM
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jarathoon

Posts: 1041
Joined: 05 September 2004

Regen SW are arguing for a more 'balanced' approach to subsidy farming in the severn estuary...

"Bristol Channel Energy
A Balanced Technology Approach - Discussion Document"

http://regensw.s3.amazonaws.co..._c541010d0b3719f8.pdf

They seem to want to compare investment returns after subsidy, rather than comparing underlying investment returns pre-subsidy. They don't discuss the economic benefit of putting a road across the barrage to link up Cardiff and Weston as part of a Severn Barrage scheme.

They do not analyse how the various schemes effect flooding risk further down the estuary. If it is to generate electrciity as the tide rises, a large lagoon may lead to higher high tides further up the estuary and associated costs incurred in terms of extra flood protection around up stream population centres.

It heavily quotes the "Severn Tidal Power Feasibility Study"
http://www.decc.gov.uk/en/cont...vern_tidal_power.aspx

Conclusions and Summary Report
http://www.decc.gov.uk/assets/...udy-conclusions-a.pdf

About Transport links this report says

"Transport links
Some commentators have suggested that a barrage across the Severn estuary should carry a new road or rail link. Such a link would be expensive as it would need to be elevated to provide adequate clearance for vessels to pass through locks. Such a development would not necessarily be less expensive than a separate construction structure. The feasibility study has commissioned work by Network Rail and the Highways Agency24 and has found no evidence that the existing road and rail infrastructure is inadequate or unable to meet anticipated traffic for at least the next 15-20 years.

It is possible that new transport links will be needed beyond 2025-30. With this in mind it would be feasible to accommodate suitable foundations either as part of the design of a barrage or subsequently by developing a design that adapted the existing structure for a future transport link. Issues associated with new transport links are not considered further in this report as further specific assessments would need to be undertaken at that time."

I don't think we know enough to rule out the barrage as the lowest cost option yet. It is always possible that the subsidy system acts to stop the most economically viable solution from being the one that ultimately succeeds.

James Arathoon


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James Arathoon
 23 December 2012 04:25 PM
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acsinuk

Posts: 153
Joined: 30 June 2007

Hi James
The building of a road from Cardiff to Minehead will be massively expensive but if it ever happens then tidal energy can be extracted by blocking the gaps underneath the arches. It may be possible to obtain a considerable amount of tidal energy by blocking just the sides and obtaining the tidal dynamic energy that is caused by the small difference in water level each side of the barrage leaving the centre section open for shipping and fish. If we could develop a tidal water wheel that will skim the energy off the low head that should do the trick!
Could be that we could fill in the gaps under the new Severn bridge and leaving the centre open for shipping and fish, develop the technology there for tidal skimming. Would be much cheaper than financing a new project.
What do you think?
Happy Christmas everyone
CliveS
 14 February 2013 11:13 AM
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catechnology

Posts: 1
Joined: 18 January 2003

Roger, surely the key to tidal power around the UK is that when it is slack water in place X, the tidal current is maximum in place Y. The tidal patterns are totrally predictable, unlike wind and solar, so the gross generation for the UK over a period should also be predictable.
Howard McC.
 14 February 2013 01:26 PM
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ectophile

Posts: 544
Joined: 17 September 2001

Originally posted by: catechnology

Roger, surely the key to tidal power around the UK is that when it is slack water in place X, the tidal current is maximum in place Y. The tidal patterns are totrally predictable, unlike wind and solar, so the gross generation for the UK over a period should also be predictable.

Howard McC.


The problem is that the UK only occupies about 10 degrees of longitude from East Anglia to the Outer Hebrides. There are two tides a day, so if it's high tide at Greenwich (0 degrees) then it will be high tide at 180 degrees as well. It will be low tide at -90 and +90 degrees. The tide will be changing fastest at about -135, -45, +45 and +135 degrees - none of which are in the UK.

So even scattering tidal barrages around the UK, there will still be troughs in the generation around the high and low tides.

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S P Barker BSc PhD MIET
IET » Energy » Tidal Power

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