Sustainability Evaluation of Hybrid Renewable Electrification Alternatives in Malawi’s Villages Using a Multi-Criteria Approach

摘要

Off-grid villages in Malawi continue to suffer from limited access to electricity due to under performance of the installed generation systems. This is largely attributable to inappropriate methodologies applied for sizing the systems that ignore sustainability indicators (technical, economic and environmental) as well as communities’ existing energy demand and future projections. This paper presents the sustainability evaluation of five types of hybrid renewable energy systems considered for deployment in three villages in Malawi. The study employed a Multi-Criteria Decision Analysis (MCDA) based on TOPSIS (Technique for Order of Preference by Similarity to the Ideal Solution) algorithm. The PV-Battery (PB), PV-Wind-Battery (PWB), PV-Diesel-Battery (PDB), Wind-Diesel-Battery (WDB) and PV-Wind-Diesel-Battery (PWDB) systems were evaluated. The study envisaged to identify suitable systems for deployment in each of the villages based on the pre-set technical, economic and environmental criteria. Under these criteria, the sub-criteria were identified which included; renewable fraction, excess electricity, total system capacity, battery autonomy, total electrical production, return on investment, simple payback, Net Present Cost (NPC), initial capital cost, operating cost, Cost of Energy (COE) and carbon dioxide (CO_(2)) emissions. The indicative values for these sub-criteria were derived from the optimization results from HOMER simulation software. The TOPSIS analysis entailed definition of energy alternatives and criteria, formulation of the decision matrices, normalization of the decision matrices, generation of weighted normalized matrices, determination of ideal and negative ideal solutions, calculation of relative separations from the ideal and negative ideal solutions and determination of relative closeness of each energy alternative to the ideal solution. For Chigunda, the PWB system was the most suitable with the highest closeness to ideal solution (C_(i)) value of 0.749 while for Mdyaka and Kadzuwa; the best alternative was the PB configuration with the highest C_(i )values of 0.708 and 0.717 respectively.