This cost is from the National Grid study: Offshore Transmission Network Feasibility Study report available on National Grid's website: http://www.nationalgrid.com/uk/Electricity/OffshoreTransmission/OffshoreApproach/
Unlike the other costs in this category, this looks at offshore transmission (not onshore). Offshore transmission is more expensive.
The study produces a high/low costs range. This data point is the high end of the range (assuming accelerated growth of the offshore electricity transmission system). The low end of the range (assuming slow growth) is entered elsewhere in the wiki.
Items that this cost excludes:
- This cost should exclude grid distribution costs (they should be in distribution cost data)
- This cost should exclude the cost of carrying electricity from new generation to the nearest grid access point (that should be in the cost of the individual generating technology).
Detail on the conditions under which this cost is valid
- Capital and operational costs are based on coordinated design approach for offshore electricity transmission infrastructure.
- The costs refer to Round 3 and Scottish Territorial Waters (STW) offshore wind projects.
- The capital and operational costs are based on the future energy scenarios Accelerated Growth scenario developed by National Grid.
- Source for costs is the Offshore Transmission Network Feasibility Study report available on National Grid's website: http://www.nationalgrid.com/uk/Electricity/OffshoreTransmission/OffshoreApproach/
- Cost based on 2010 prices
- Assumes that Round 3 and STW offshore wind projects will be connected to the National Electricity Transmission System and will have offshore transmission assets.
- Operating Costs quoted are for maintenance costs only.
Low cost estimate (the accelerated growth scenario):
- Accerelated Growth Capital Cost at 2030 is £29.2bn; Maintenance Costs at 2030 is £368m.
- Accelerated Growth includes 39.8GW of installation capacity for offshore wind projects (Round 3 & STW).
- To convert into wiki format: £13.4bn / 39.8 GW = £336.7m/GW.
- Opex is £173m. Not clear how to convert this to wiki format.
High cost estimate (the slow growth scenario):
- Slow Progression includes 16.8GW of installation capacity for offshore wind projects (Round 3 & STW only).
- Slow Progress Capital Costs at 2030 is £13.4bn; Maintenance Costs at 2030 is £173m.
- To convert into wiki format: £29.2bn / 16.8GW = £1770m/GW.
- Opex is £368m. Not clear how to convert this to wiki format.
- We have decided against including this estimate in the costs range for the Calculator because it would skew the results and make transmission costs appear artifically high. It would give the misleading impression that transmission costs could be this high - when in practice, only offshore transmission costs under pessimistic assumptions could be this great.