Carbon neutral island energy system transition - A model-based analysis of sector coupling between the electricity, industry and heat sectors

Although having access to renewable sources of energy, islands often face challenges of security of energy supply, climate change impacts and drawbacks of fossil fuel dependency. Utilization of renewable resources, increasing energy efficiency, and securing an affordable energy supply are key elements of the sustainable energy transition of islands. In this study, a dynamic energy system optimization model is developed using the TIMES modeling framework and is applied from the perspective of an island’s energy system. Carbon neutral energy system scenarios are designed and integrated into the model to assess system impacts of various industrial development options in connection with investment in large-scale offshore wind power for the case of a Swedish island. The results show a transition in the power and heat sectors for all the scenarios. Ground-source heat pumps (HPs) and district heat (DH) replace electric boilers and ambient-air HPs. The abundancy of renewable electricity generation, either due to non-existence of an energy intensive industry on the island or investments in large-scale wind power plants, leads to lower marginal cost of electricity generation. Consequently, the use of renewable (seawater) and low-temperature excess heat (EH) sources in large-scale HPs and direct use of high-temperature EH in DH systems increase. In turn, the EH heat sources replace biomass combustion in heat-only boilers. The intermittent renewable power generation is balanced by electricity import from the mainland (if allowed), biodiesel gas turbines, DH production in new biogas combined heat and power plants and large-scale HPs, and an existing heat storage.