Updated: Apr 21
The renewable energy potential of the Scottish islands has long been recognised, with Costa Hill in the Orkney islands hosting the first grid connected wind turbine in the UK back in 1951 . Today, wind turbines on the island regularly achieve capacity factors (the proportion of the maximum potentially generated energy) upwards of 50%. This was recognised for the first time by the UK regulator Ofgem in 2007 with publication of a call for consultation on how best to unlock the energy potential of the islands . Between 2003 and 2014, installed wind capacity on Orkney went from 8.2 MW to 43.8 MW  – over 500% ! The three main island groups of the Shetlands, Orkney and the Western Isles have been so successful that small-scale and megawatt-scale community owned capacity has reached the limits of local infrastructure, resulting in high levels of curtailment when generation is high. In 2014, this was estimated to be as high as 40-50% for certain generators in Orkney for example, meaning a loss of 40-50% of revenue from the sale of electricity .
Island interconnections could play a key role, because could facilitate increased renewables, reducing curtailment and increasing maximum allowable capacity on the system . Increased geographic diversity, facilitated by interconnection, results in more consistent renewable generation, meaning less CO2 intensive balancing actions . Increased renewable capacity on the islands could support the local economy - meaning interconnections could have benefits both at a local and national level.
Figure 1: Scottish island interconnections for Western Isles (marked as 6), Shetland (7) and Orkney (9).
Despite this, discussions for improved interconnections stalled, until recently. Ofgem and developers were caught in a chicken and egg scenario: without guaranteed capacity planned, Ofgem were unwilling to commit to new interconnection; without interconnection, developers were less likely to commit to planning developments. High costs to connect to the mainland and details of how this would be paid for also slowed development. During the period government support flip-flopped: remote-island wind was introduced as a contracts-for-difference (CfD) category in 2013, then removed in 2015 (alongside onshore wind and marine energy), then reinstated in 2019 .
Discussions between Ofgem and SHEPD (the distribution network operator for North Scotland) have begun to reach agreement though, with the Shetland interconnection being approved in 2020. Main contractors for the works have since been appointed and ground work has commenced . Capacity for Orkney and the Western Isles has succeeded in the most recent CfD allocation rounds, but SHEPD’s method of recouping the costs has not yet been approved by Ofgem . With the success of the Shetland interconnection, it should only be a matter of time before the other two main ones will also be approved.
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