Incorporating Negative Values in AHP Using Rule- Based Scoring Methodology for Ranking of Sustainable Chemical Process Design Options

Adopting Analytical Hierarchy Process (AHP) for selection and ranking of sustainable chemical process design that considers the trade-off between economic feasibility, environmental friendliness and social advantages offers good decision methodology for multi criteria problem. Typical AHP problem however are limited to handle only positive preferences. The introduction of negative preferences into AHP often creates various contradicting scenarios that result in spurious and inconsistent decision. To overcome such contradiction a rule-based scoring methodology is proposed. The system works by initially define each indicator according to its value-desirability behaviour. Next, using specific conversion factors that act accordingly to that behaviour the indicators value is converted into a credit-penalize scoring concept. Positive preference is credited with positive value while negative preference is penalized with negative value that shows its undesirability. Using a rule-based approach the score which span over positive and negative value are treated to elicit the final selection and ranking solution. The functionality of the proposed methodology will be demonstrated to selection and ranking of several biodiesel case scenarios in presence of positive and negative preferences.