The East Anglia 1 Windfarm

connection to the transmission grid:

A Proposition for a Better Way

 

This article covers our proposal for an alternative strategy for connecting the Anglia 1 Windfarm to the UK transmission grid. Before presenting our thoughts I should first point out that we warmly welcome the development of the offshore windfarms and are not anti nuclear. We work to support the development of a sustainable, low carbon energy system for the UK that can fully integrate into the European Grid and maximise our Nation's potential as a renewable energy exporter. Importantly, we work to see this achieved in a manner that has the least damaging impact on our environment whilst at the same time doing so in an economically beneficial manner that is in the best interests of our Nation.


Background

It is clear that the single largest demand for new electricity transmission capacity in our region comes from the recently announced Anglia 1 Windfarm which is to be developed jointly by Scottish Power Renewables and Vattenfall. Currently, National Grid have offered a connection at Bramford which therefore brings all of this power (7.2 gigawatts (GW)) together with up to 3.2GW from Sizewell through our local Bramford to Twinstead "transmission corridor". National Grid propose to deal with this by building yet another line of pylons through this corridor and prospectively through our AONB. This in our view creates a massive security issue along with unacceptable environmental damage. 


Network Security

The chief threat to and cause of failure to overhead lines is environmental, i.e. the weather. It would therefore be the case that a 1987 type storm could cause catastrophic damage the comparatively densely located transmission system if reinforced as currently proposed in this corridor and create an outage of 15 - 20% of the nation's power. This we see as an "all our eggs in one basket" problem.


Recent Deveopments

On the 18th October 2010, the Government announced Bradwell in Essex as a preferred development site for a new nuclear reactor power station. Bradwell currently has an unused (since the closing of the existing nuclear plant) connection to the electricity transmission grid at Rayleigh. This is a line of pylons carrying 275kV lines and is already scheduled for upgrading to 400kV. The output of a new Bradwell reactor would be circa 1.6GW. A line of upgraded, replacement pylons from Bradwell to Rayleigh could carry 2 x 3.3GW circuits = 6.6GW total capacity, as is proposed to be implemented in the Bramford to Twinstead corridor. This without substantially increasing the environmental impact of the Bradwell to Rayleigh pylon line.


Scottish Power Renewables / Vattenfall (SPR/V) have announced that they wish to take the undersea HVDC power cables from the Anglia 1 windfarm, down the coast  and then onshore, preferably underground to Bramford and indeed current information suggests that the entire output from Anglia 1 will connect to the grid there.


We believe that there is a better way to connect the windfarm that is in everyone's best interest and we have put this idea to SPR/V, National Grid, effected local councils and the Government (DECC). 



The Proposition

Public domain documents suggest that there will be at least three nodes or collection points within the Anglia 1 windfarm where the output from the turbines is brought together before being sent ashore. What we would like to suggest is that the first node in the section of the windfarm closest to shore, and we believe the first to be implemented, is indeed connected to Bramford. But that the remainder of the windwarm is connected through Bradwell. This does not require a substantially longer HVDC cable connection than the Bramford (underground) option. It would require a converter station at Bradwell but this would mean a reduction of the size of the converter station site needed at Bramford under the current proposal. Our proposition therefore is that (say) 2.2GW from Anglia 1 is connected to the grid at Bramford and together with 3.2GW from a fully implemented 2 reactor Sizewell is transmitted via the existing, reconductored pylons in the Bramford - Twinstead corridor which would have a capacity of 6.6GW.  The remaining 5GW from Anglia 1 would be landed at Bradwell and together with 1.6GW from the new reactor would be transmitted into the grid at Rayleigh via the newly (and scheduled) upgraded, existing Bradwell - Rayleigh pylon line. This proposition assumes that the fossil fuel generation in this area from the two new gas powered stations at New Holland and Kings Lyn is managed to mitigate low output from the wind farm during low wind periods and that there would never be a time when every generator in the region was running flat out. (In the future, we trust that fossil fuel generation (in the form of gas fired generators) will be a renewable replacement form of generation and will not simply be added to total capacity.) NB: in order to fully utilise the south going 400kV circuits from Twinstead to deliver the renewable/low carbon energy to the grid, we also propose a switching station at Twinstead which would greatly enhance system security with these increased loads.


The Benefits of this proposition:-


improved security of supply through spreading transmission geographically and security improvements through the implementation of a switching station at Twinstead

removes the need for more pylons on land: this strategy has lower environmental impact than current proposals

reduces transmission charges to generators (SPR/V) as Bradwell is closer to London's energy users (the power will be transmitted through fewer NG charging zones)

requires only currently planned upgrades to conductors and pylon lines on the existing grid plus a switching station at Twinstead

reduces on-land tunnelling and underground installation of HVDC cables and attendant costs

is in keeping with NG/Ofgem/Government objective of fully utilising existing infrastructure rather than building new

allows for a built up implementation spreading connection investment as generation comes on-line and removes need for on-land cable to be implemented at full capacity before such capacity is needed


We believe that this strategy to be in all of our best interests and can help free our landscape of the threat of further pylon blighting. It does not conflict with other strategies we have put forward or indeed the future integration of the UK grid into the developing European Grid.





REFS:


Anglia 1 Offshore Windfarm Leaflet

http://www.eastangliawind.com/assets/downloads/221186_EAOWLEAFLET.pdf


Anglia 1 website: 

http://www.eastangliawind.com/


Data Pack from the East Anglia Offshore Wind (EAOW) public information days

http://www.eastangliawind.com/assets/downloads/221186_EAOW_boards.pdf