The role of interconnectors in decarbonising Great Britain’s electricity system

The role of interconnectors in decarbonising Great Britain’s electricity system

Dr Waqquas Bukhsh, University of Strathclyde
Dr Callum MacIver, University of Strathclyde
Prof Keith Bell, University of Strathclyde


Electricity interconnectors are considered as key investments for enhancing the security of supply, increasing overall social welfare and helping achieve decarbonisation targets through the optimal utilisation of the installed renewable generation capacity. The European Commission has been promoting the development of interconnections in parallel to market liberalisation and has set an ambitious target of 15% import capacity as compared to the installed generation capacity for all member countries by 2030. [1-2]

For islanded nations like Great Britain (GB), meeting these interconnection targets entails the use of long-distance HVDC subsea cables to connect to neighbouring markets. At the time of writing, the GB electricity system has interconnection capacity of 5 GW: 1 GW to the Island of Ireland and 4 GW to continental Europe. The 5 GW represents approximately 6% of the overall generation capacity in GB New interconnection projects with Denmark, France, Norway and Ireland, as shown in Table 1, mean that GB interconnection capacity is likely to be increased by more than 100% by 2025.

This talk will take-up the following questions:

  • What impact will increasing interconnection capacity have on the cost of operating a secure and reliable GB system
  • What will be the impact of increasing GB interconnection capacity on GB and European carbon emissions?
  • What role the Carbon Price Support (CPS) mechanism plays in decarbonisation of the GB system?

Insights and results will be presented from a recently concluded research project that investigated the aforementioned questions. A representative model of the European electricity system was used along with generation and demand scenarios from the ENTSO-e Ten Year Network Development Plan [2] for the years 2020 and 2025. Our results show that the impact of increasing GB interconnection on carbon emissions is largely dependent on two factors: the relative short-run cost of gas and coal generation, i.e. their respective positions in the ‘merit order’, and the CPS mechanism in GB. These two factors alongside the scale of renewable energy deployment determine the extent to which GB transitions away from being a large net importer of electricity towards a more balanced or even net exporting nation. In the scenario where CPS stays at 18£/tCO2e and coal is cheaper than gas, GB is a net importer of electricity. This sees the displacement of moderately polluting gas generation in GB while at the same time facilitating the increased use of more heavily polluting coal and lignite generation in continental Europe. Contrary to the intention of the CPS, it thus increases carbon emissions when assessed for the w hole of Europe.

Imports via interconnection and generation from wind and solar are forms of non-synchronous generation, which has zero inertial contribution to the system. Due to system stability considerations, the GB electricity system with its current set of frequency response products has minimum requirements for inertia so that the system can withstand an unplanned generation or demand outage. In that context, the National Grid Electricity System Operator may have to restrict imports from the interconnectors and/or re-dispatch generation within GB to meet minimum inertia requirements, all of which increase costs of system operation. The analysis shown in this presentation highlights that these costs can be of the order of hundreds of millions of pounds per year. This highlights the need for whole electricity system operation to be properly considered when prospective interconnector projects are assessed and should provide a strong motivation for review of existing ancillary services..




[1] European Commission, ENTSO-e Ten Year Network Development Plan, 2018. [Online] Available:


[2] European Commission, Study on the benefits of additional electricity interconnections between Iberian Peninsula and rest of Europe, 2016. [Online] Available:


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