Optimization of Island Electricity System

Abstract

Climate change without adequate countermeasures has become one of humanity's greatest threat. Energy production by means of renewable energy sources is therefore one of the crucial measures that will play a paramount role in reducing the pollutant emissions of fossil fuel dependency. Small islands in particular are an exemplary case of the extraordinary dependence on oil, the energy system often being entirely dependant on diesel generators. The relative high cost of sustaining this practice in combination with the geoeconomic properties of islands provides a unique incentive for the transition to renewable energy. By definition, islands are surrounded by water, making them highly vulnerable to the effects of climate change. In addition to the risk of being surrounded by water, it also provides a vast set of possibilities. Harnessing energy from waves, tides and the difference in seawater temperatures (OTEC) are just some of the examples. In this thesis, the effect of ocean energy integration is investigated. A simulation and optimization model of the electricity supply system is developed. A multi-objective genetic algorithm optimization regarding cost (LCOE) and renewable energy integration is performed. The model covers; PV solar, wind, tidal, wave and OTEC as well as battery storage as components of a renewable energy system. The resulting model is applied to two case study islands (Shetland and Aruba), the effect of the hybrid system including ocean energy technologies is determined. The cost optimal system was found to produce energy with an LCOE below the conventional fossil fuel energy cost. This corresponds to a renewable energy share of approximately 65%, consisting solely of wind energy. The cost was determined to have a significant influence on the system configuration. Currently, due to the high cost of energy based on their pre-commercial stage, ocean energy sources are added to the energy mix at high renewable energy shares (above 75% renewable coverage). The hybrid systems including the ocean energy sources displayed an evenly spread energy production. Based on this study, the future of integrating ocean energy provides an encouraging outlook. Cost will need to be reduced further for ocean energy to become economically viable. With the right investments in ocean energy, this process can be accelerated and will become viable.