Combining Behavioural Topsis and Six Multi-Criteria Weighting Methods to Rank Biomass Fuel Pellets for Energy Use in Sweden

Abstract

Growth in biomass fuel pellets is expected to accelerate in the coming decades as EU energy and climate policies are implemented and the European Green Deal pursues carbon-neutrality in the EU by 2050. The Swedish pellet industry is an example of a successful sector whose capacity has grown continuously to feed rising domestic and European demands. A wide variety of feedstocks (biomass) for producing fuel pellets is available to choose from. The use of multi-criteria decision analysis (MCDA) to support such choices has the potential for more transparent and better decision-making overall. This study applies the behavioural TOPSIS, a prominent MCDA technique, to rank pellets for energy use in Sweden produced from under-utilised forest and agricultural biomass. Seven criteria, both quantitative and qualitative, were selected and used to assess and ultimately rank the biomass pellets. The alternatives include 88 types of biomass pellets from 11 biomass materials. Possible attitudes of an expert towards the risk of losses (risk averse, risk neutral and risk-seeking) were combined with six sets of criteria weights obtained using six weighting methods – a total of 18 input settings (scenarios). Despite having different input settings, almost identical results were obtained in all scenarios, meaning that the rankings were stable and consistent. Across all 18 scenarios, pellets produced from a reference spruce/pine sawdust blend are ranked ahead of other pellet types. Pellets produced from Scots pine bark exhibited stable and consistent rankings across all scenarios; and thus this biomass is the second-best overall. The next best materials overall are poplar, reed canary grass and wheat straw, whereas torrefied pellets (torrefied beech, poplar and wheat straw) were ranked last in all scenarios. Combining behavioural TOPSIS and a variety of criteria-weighting methods is a meaningful way of improving decision-making with respect to producing a more valid and reliable ranking of biomass fuel pellets for energy use in Sweden.

Keywords: Multi-criteria decision analysis, behavioural TOPSIS, criteria weighting methods, pellet quality, Biofuel, Pelleting