Strategies for decarbonising the energy system in Finland

Finland has ambitious climate mitigation goals and intends to become carbon-neutral already by 2035. However, the pathways to these targets remain unclear. Previous studies on the Finnish energy system have often focused on assuming certain future system configurations, seldom considering possible future pathways for the whole energy system through energy system optimization, and particularly not with an hourly level resolution. The focus of this thesis is to analyse and compare future scenarios for decarbonising the Finnish energy system. A particular focus is given to the three main pillars of the Finnish energy and climate policies: forestry biomass, nuclear power, and wind power, while also considering the uncertainty of future demand, policies, costs and renewable resource availability. As wind power is often an integral part of a decarbonised future energy system, the thesis also covers wind power integration with different system flexibility measures. The main research question of the thesis is what kind of an energy system would meet the climate targets most cost-effectively and be the most resilient to future uncertainties within given system limitations. The main methodology of the thesis is studying possible energy system pathways by constructing and analysing cost-optimized energy system scenarios with techno-economic energy system modelling. For this purpose, a comprehensive simulation model of the Finnish energy system was developed, covering the electricity, heat and fuel sectors. The thesis concludes that there are many different optimal decarbonised energy system pathways for Finland. Common denominators for all scenarios seem to be a high level of decarbonised electricity production (nuclear and wind power), electrification of heat production, active international power exchange, and fossil fuel replacement with biomass. Effective wind power integration would also require system-level thinking and flexibility measures, the most cost-effective options being power-to-heat and curtailment. The thesis also suggests that the energy system's resilience against political disruptions could be improved by increasing and diversifying the renewable resource base, utilising sector-coupling and other system flexibility measures, and improving energy efficiency. However, no single system configuration stands out as the most resilient to future uncertainties.