A Multi-Criteria Decision Analysis Tool Based on PROMETHEE II and TOPSIS to Compare Steel, Green Steel, and LVL Timber Wind Turbine Towers for Onshore Wind Power Projects in Sweden

Sammanfattning

This thesis addresses the problem of selecting between conventional and emerging wind turbine tower concepts by developing a transparent multi-criteria decision analysis (MCDA) framework for tall onshore wind applications. Three alternatives are considered: conventional tubular steel, green low-carbon steel and laminated veneer lumber (LVL) timber towers. The alternatives are evaluated against nine sub-criteria covering technical, economic, environmental, social and logistical dimensions. Performance scores are compiled from literature, life cycle assessments, technical reports, and combined with several sets of criterion weights derived from four experts in the Swedish wind sector, the average of experts’ weight profile, as well as equal, entropy-based and analyzer-suggested weights. The MCDA model is implemented in an Excel-based tool using PROMETHEE II and TOPSIS methods. Spearman’s rank correlation is used to assess consistency between methods. The results show method- and weight-dependent ranking patterns. In PROMETHEE II, conventional steel ranks first under all expert-informed weight sets, while LVL timber ranks first under equal, entropy, and analyzer-suggested weights. Also, the green steel tower is consistently ranked last. In TOPSIS, conventional steel is preferred in most weighting schemes, while LVL timber is ranked last in most cases; the exceptions occur under equal weights (green steel first) and the analyzer-suggested profile (LVL timber first). Spearman’s rank correlation between PROMETHEE II and TOPSIS varies from partial agreement to complete reversal across weighting schemes indicating that robustness depends on both the weighting perspective and the MCDA aggregation logic. PROMETHEE II net flows and TOPSIS closeness coefficients are reported to indicate the decisiveness of each ranking by showing the separation between alternatives under each weighting scheme. Overall, the study demonstrates that a structured MCDA approach can clarify trade-offs between conventional steel, green steel, and LVL timber towers and make the influence of stakeholder priorities on technology choice transparent.