A comparison of the environmental benefits of bagasse-derived electricity and fuel ethanol on a life-cycle basis

• Published in: Energy policy Vol. 34; no. 17; pp. 2654 - 2661
• Main Authors: Botha, Tyron, von Blottnitz, Harro
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.11.2006; Elsevier; Elsevier Science Ltd
• Series: Energy Policy
• Subjects: Acidification; Alternative energy sources; Applied sciences; Bagasse; Benefits; Cellulose; Climate change; Co-generation; Coal; Cogeneration; Comparative studies; Conservation; Crop residues; Economic data; Electric energy; Electricity; Energy; Energy economics; Energy efficiency; Energy policy; Environmental protection; Ethanol; Eutrophication; Exact sciences and technology; Fermentation; Food processing industry; Fossils; Fuels; General, economic and professional studies; Global warming; Life cycles; Life-cycle assessment; Methodology. Modelling; Natural energy; Renewable energy; Residues; Resource conservation; Sugar; Sugarcane; South Africa; Africa; Ethanol; Co-generation; Life-cycle assessment; Bagasse; Case study; Cogeneration; Environment impact; Life cycle analysis; Production; Biofuel; Electric power production; Comparative study
• ISSN: 0301-4215; 1873-6777
• DOI: 10.1016/j.enpol.2004.12.017

The energetic utilisation of agricultural residues is considered to be an important element in any strategy to achieve renewable energy targets. In the approximately 80 cane-sugar producing countries there is potential to make better use of the fibrous residue known as bagasse. Subject to improved energy efficiency, sugar producers could supply energy either as “green”, co-generated electricity, or as fuel ethanol through cellulose hydrolysis followed by fermentation. This paper compares their projected environmental benefits from a life-cycle perspective, using South African data. Mass and energy analyses were prepared for the two systems and a base case (producing sugar with current methods), relative to the annual sugarcane production on one hectare. In both cases, the environmental burdens avoided by replacing an equivalent amount of fossil energy were included. The results obtained confirm that for all the impact categories considered, both “bioenergy” products result in environmental benefits. The co-generation option results in lower energy-related emissions (i.e. lower global warming, acidification and eutrophication potentials), whereas the fuel ethanol option is preferred in terms of resource conservation (since it is assumed to replace oil not coal), and also scores better in terms of human and eco-toxicity if assumed to replace lead-bearing oxygenates.