Nid safbwyntiau’r Arolygiaeth Gynllunio yw’r rhai a fynegir ar y dudalen hon. Yr hyn a ddangosir yma yw cynnwys a gyflwynwyd i’r Arolygiaeth Gynllunio gan y cyhoedd a phartïon eraill â buddiant, sy’n rhoi eu barn ynglŷn â’r cynnig hwn.
Cysylltiad Gogledd Cymru
Derbyniwyd 27/11/2018
Gan Peter Gillett
Gan Peter Gillett
Sylw
“Estimated Costs of Offshore HVAC Connection, Strategic Option 6
National Grid appear to have used out-dated cost metrics on which to base the estimates for the offshore options. This is unacceptable at this stage of the project.
There are a number of examples throughout the world where high power rated HVAC submarine cables have been successfully installed at 400kV and above.
The cable manufacturers are now able to produce HVAC power cables with a conductor cross section area of 2500sqmm
The NG subsea HVAC strategic option report does not state how many submarine cables are specified and hence costed. Based on the latest technology, a double circuit connection can be achieved with 12 cables whereas, until recently, 18 cables would have been laid to handle the required power rating.
Over the last few years there has been a massive growth in the use of offshore HVAC cables.
Most windfarm cables use HVAC technology and the power rating of recent and planned windfarms require cables of greatly increased capacity.
It is recognised that HVDC is unsuitable for the North Wales Connection although HVDC is extensively used for submarine interconnectors. Indeed the first subsea interconnector between Britain and France was commissioned in 1961
NG state that the cost of HVAC offshore for Wylfa Pentir Hybrid is £1145m.
Wylfa Pentir undergrounding is stated as £905m however this excludes the cost of the Menai tunnel estimated at £200m which brings the total to £1105m.
Undergrounding is very intrusive to the farming community and the landscape never fully recovers. At this stage, it cannot be guaranteed that the third Menai bridge will go ahead.
National Grid should be tasked with producing a detailed estimate of the Pentir hybrid option based on manufacturers’ cable and installation quotes. Until this work has been completed and published the offshore HVAC option cannot be rejected.
Horizon has made known their opposition to offshore connections possibly on reliability grounds. It should be remembered that NGET under SQSS regulations are required to build four circuits, any one of which can take the full output of Wylfa, two of these circuits use the existing pylons across Anglesey.
The location of the beach head on SO6 clearly has not been surveyed and reported. NGET simply say that the beach landing will be “south of Caernarfon.”
This amounts to level of detail of a “back of the envelope desk study”. At this stage of the DCO, NGET should have conducted and reported the results of a detailed survey of the landfall and maps showing the route to the grid.
The DCO should be rejected until NGET has conducted and reported a detailed up to date cost estimate for S06
P E Gillett
B.Eng., MA, DipMarTech
”
National Grid appear to have used out-dated cost metrics on which to base the estimates for the offshore options. This is unacceptable at this stage of the project.
There are a number of examples throughout the world where high power rated HVAC submarine cables have been successfully installed at 400kV and above.
The cable manufacturers are now able to produce HVAC power cables with a conductor cross section area of 2500sqmm
The NG subsea HVAC strategic option report does not state how many submarine cables are specified and hence costed. Based on the latest technology, a double circuit connection can be achieved with 12 cables whereas, until recently, 18 cables would have been laid to handle the required power rating.
Over the last few years there has been a massive growth in the use of offshore HVAC cables.
Most windfarm cables use HVAC technology and the power rating of recent and planned windfarms require cables of greatly increased capacity.
It is recognised that HVDC is unsuitable for the North Wales Connection although HVDC is extensively used for submarine interconnectors. Indeed the first subsea interconnector between Britain and France was commissioned in 1961
NG state that the cost of HVAC offshore for Wylfa Pentir Hybrid is £1145m.
Wylfa Pentir undergrounding is stated as £905m however this excludes the cost of the Menai tunnel estimated at £200m which brings the total to £1105m.
Undergrounding is very intrusive to the farming community and the landscape never fully recovers. At this stage, it cannot be guaranteed that the third Menai bridge will go ahead.
National Grid should be tasked with producing a detailed estimate of the Pentir hybrid option based on manufacturers’ cable and installation quotes. Until this work has been completed and published the offshore HVAC option cannot be rejected.
Horizon has made known their opposition to offshore connections possibly on reliability grounds. It should be remembered that NGET under SQSS regulations are required to build four circuits, any one of which can take the full output of Wylfa, two of these circuits use the existing pylons across Anglesey.
The location of the beach head on SO6 clearly has not been surveyed and reported. NGET simply say that the beach landing will be “south of Caernarfon.”
This amounts to level of detail of a “back of the envelope desk study”. At this stage of the DCO, NGET should have conducted and reported the results of a detailed survey of the landfall and maps showing the route to the grid.
The DCO should be rejected until NGET has conducted and reported a detailed up to date cost estimate for S06
P E Gillett
B.Eng., MA, DipMarTech
”
