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Published:
July 16, 2008
Exclusive:
Plans for 'radically different' £15bn barrage unveiled
 Brand
new plans for a £15billion Severn Barrage that would protect
the Burnham-On-Sea area from flooding in the Bristol Channel are
unveiled today, Wednesday (July 16th).
Speaking
for the first about the project, engineer Rupert Armstrong Evans
told Burnham-On-Sea.com about his plans for a 15-mile barrage
that will run from Minehead to Aberthaw in Wales.
The
'Tidal Reef Project' is radically different to previous schemes
planned for Brean Down to Lavernock Point, which critics say would
leave Burnham, Brean and Berrow exposed to tidal erosion and potential
flooding.
Mr
Armstrong Evans' involvement in tidal and wave power goes back
30 years, having developed sea water powered turbines for oil
companies.
He
told Burnham-On-Sea.com: "What I am proposing is a radically
different concept for tidal power generation that is driven by
the need to address environmental issues before than after the
engineering has been designed."
 "I
am suggesting a consensus of environmental imperatives are used
to define the requirements, in much the same way as the North
Sea defined the requirements for building oil platforms, and not
the other way round."
"Our
proposal is for a barrage 'system' and not one particular turbine
design or layout. An outer barrage location from Minehead to Aberthaw
and bi-directional generation is favoured."
His
proposal is for a wall of up to 1,000 water turbines to be built
across the 15-mile stretch of estuary, each producing 4 mega watts
of electricity. There is a possibility that wind turbines could
also be built on top, as pictured at the top of this page.
"The
project would comprise of 20km of turbine caissons located over
a seabed causeway of pre-cast concerete foundation units, which
in turn would be anchored with piles and armour stone. Over 1,000
turbines of 10 metres diameter would produce 500 mega watts for
about twice the generation period of the proposed Lavernock Point-Brean
Down barrage. The annual generation could therefore be in the
order of 20 TWh."
 The
scheme would have an estimated cost of £15 billion and take
around six years to build, he added. "I would expect stretches
of the barrage to be leased to private power companies to minimise
the overall start-up costs."
"The
Burnham-On-Sea area would be far better protected under this scheme
not just because it will be behind the barrage, but also because
in the event of a storm surge we would control the opening of
the barrage to regulate the maximum upstream water levels while
land drainage outfalls at a number of loatons compromised by the
Lavernock Point-Brean Down barrage 'holding' the high water for
several hours would be unaffected."
He
went on to claim that the 'Tidal Reef Project' would also produce
more power than the Lavernock Point-Brean Down barrage.
"According
to a 2007 study by Black and Veatch, a barrage west of Minehead
would produce 50% more electricity due to the longer power generation
period in between tides."
"There
is as much energy lower down the estuary where the height of the
tide is lower, it is simply more difficult to capture this energy
because the volume of water that has to be passed through the
turbines is much greater because of the lower differential head.
More turbines are required, but they are simpler in construction
and each one is around 5 mega watts. With the 'reef system', the
generating period is more than doubled and because the basin size
is also larger, the available energy is also increased."
The
scheme is due to be discussed in further detail at an environmental
conference later in the month.
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