Vision for 100% renewable Åland Islands: Master's thesis

    Research output: ThesisMaster's thesis


    Energy systems throughout the world are undergoing a transition where renewable energy is substituting combustion of fossil fuels in power and heat production. The motive for the energy transition origins from climate goals that are set out to limit global warming well below two degrees from pre-industrial levels. The objective of the thesis is to study how an existing energy network and local characteristics can be utilized to transform an energy system to operate 100% on renewable energy. As future energy systems are expected to rely highly on variable renewable energy (VRE) generation, the thesis also intends to study which additional investments on unit and system level elements would increase flexibility in an energy system with high intermittency in power supply. The energy system of Åland Islands is studied as a case example, as different stakeholders are currently aiming to convert the island fully renewable by 2025. The thesis outlines the energy system of Åland Islands to comprise of the regional power grid and district heating network located in the capital Mariehamn.

    Based on literature review, three energy system scenarios were built to represent three alternative energy transition pathways for Åland Islands to be implemented by 2025. An energy system modelling tool developed at VTT was utilized to define the cost-optimal configuration of thermal production units in relation to scenario-wise capacities of VRE generators, flexibility elements and power interconnectors. Modelling results were utilized to evaluate technical feasibility as well as economic and environmental impacts of the studied energy transition pathways. In addition, value of additional flexibility investments in demand and supply balancing was studied.

    Due to local conditions, Åland is able to base its power supply greatly on intermittent wind energy by 2025. As a key finding of the thesis, strengthening the link between power grid and district heating network via a bio-CHP unit would increase profitability and self-sufficiency of an energy system with high reliance on variable power supply especially, when the CHP unit is integrated to a thermal energy storage (TES). Feasibility of bio-CHP as a flexibility element was found to be reliant of biomass availability and price, however, neither is considered as a constraining factor for bio-CHP applicability in Åland Islands. An additional investment on a centralized electric boiler was discovered to increase internal utilization of local VRE supply, however, resulting in lower profitability of bio-CHP investment as electric boiler was discovered to reduce full load operating hours and annual energy output of the CHP unit. The role of the applied stationary electrochemical batteries were found to be negligible on system-level VRE balancing while usability of stationary electrochemical batteries in short-term grid balancing were unabled to be studied due to the chosen temporal scale in the modelling tool.

    By investing on local energy assets, Åland would be able to cut reliance of imported electricity to reinforce power self sufficiency on the island. Environmental benefits would arise from discarded fossil carbon emissions from power and district heating sector and as a potential net exporter of renewable energy, Åland would be able to decrease utilization of fossil fuels in surrounding power areas as well. Although the renewable energy transition in Åland Islands is technically possible and brings out environmental benefits, the studied renewable energy transition pathways for Åland Islands were discovered to be economically unprofitable. The current market model on the island has to be shaped to support local renewable generation. An alternative would be to partly fund the renewable energy transition in Åland Islands by public financial support schemes.

    Methodology applied in the thesis related to required input parameters for energy system modelling and methods to examine the modelling results can be employed to investigate potential renewable energy transition pathways in energy systems throughout the world. The modelling results related to Åland Islands can be applied to evaluate potential benefits of bio CHP and TES in facilitating VRE integration in areas aiming to utilize district heating network to balance intermittent VRE supply. In addition, the results can be utilized to evaluate the applicability of electric boiler in increasing internal utilization of locally produced VRE supply. However, as the energy transition pathways studied in the thesis were designed in particular to Åland Islands, more detailed techno-economic analysis of existing energy system elements and local characteristics should be performed to the region where similar approach to renewable energy transition and VRE integration would be applied as in Åland Islands in this study.
    Original languageEnglish
    QualificationMaster Degree
    Awarding Institution
    • University of Oulu
    • Thomasson, Tomi, Supervisor
    • Tähtinen, Matti, Supervisor
    • Louis, Jean-Nicolas, Supervisor, External person
    • Pongrácz, Eva, Supervisor, External person
    Award date23 Apr 2019
    Publication statusPublished - 9 May 2019
    MoE publication typeG2 Master's thesis, polytechnic Master's thesis


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