Modelling the Energy Transition on the Western Isles, Scotland : Scenario analysis to compare future pathways on the island of Lewis and Harris

Abstract: Renewable energy potential at a local level is important if communities are to play a role in the wider global energy transition. The following thesis studies the ongoing transition on the island of Lewis and Harris, part of the Western Isles, Scotland. A PLEXOS energy model is constructed, focusing on the island’s electricity system. Future local renewable potential is investigated through several scenarios. Electrification of heating and transportation sectors is assumed, via high uptake of heat pumps and electric vehicles, as the replacement of the failed subsea mainland interconnection and the future of the island’s diesel power station are explored. Battery energy storage systems provide a potential solution to the decommissioning of the diesel power station, coupled with additional solar photovoltaics to complement already installed wind resources. The importance of interconnection capacity is highlighted if the island is to become a major exporter of wind power, although through sensitivity analysis it was found that the economic viability of new wind turbines is uncertain due to falling mainland electricity prices. The representation of the mainland is identified as a key limitation within the study, in particular the projection of future electricity prices and their potential temporal relationship with local wind production. Greater consideration here would be beneficial. Expansion of the modelling to include heating demands at a wider level, alongside potential hydrogen production, could be interesting areas to explore further.