Using a multi-method approach for decision-making about a sustainable local distributed energy system: A case study from Finland

Distributed energy systems (DESY) are used in many households as an alternative to conventional centralized energy production. While centralized energy production does offer certain advantages, there is growing interest in smaller distributed renewable energy production options. This study uses combines two different methodologies, namely life cycle assessment (LCA) and the analytical hierarchy process (AHP), to assess the sustainability of three energy scenarios, with the aim of finding the most sustainable combination of DESY options for a case municipality of approximately 220 inhabitants in Western Finland. The local production potentials of five renewable options: wind, small-scale hydropower, biogas, small-scale combined heat and power plants and photovoltaics (PV) were calculated after which the criteria for sustainability assessment were selected. Three scenarios were created to represent production mixes capable of meeting the electricity consumption needs of the area: 1) a non-biomass renewable energy option of wind power and hydro power, 2) hydropower combined with solar electricity and 3) a small-scale combined heat and power (CHP) plant with solar electricity. In addition, electricity production from biogas was used to bridge the gap between consumption and production in all three scenarios when needed. The values from the sustainability criteria were calculated by using LCA software database (GaBi 6.0) -information and literature values. Then the experts of the local energy production prioritized the sustainability criteria by pairwise comparisons resulting in valuations in sustainability assessment. The findings indicate that the application of two different methodologies strengthened the sustainability analysis and provided a large and relevant information base to support local decision-making in finding the optimally sustainable local DESY. In general, the results imply that scenario 1 with local hydropower and wind power has fewer negative impacts than other scenarios with PV and biomass utilization options. In the future, applying AHP in LCA may be useful in local sustainability assessment with stakeholder participation and in weighting other than environmental aspects of sustainability.