The generation of residual biomass during the production of bio-ethanol from sugarcane, its characterization and its use in energy production Waldir Antonio Bizzo n , Paulo César Lenço 1 , Danilo José Carvalho, João Paulo Soto Veiga 2 Faculty of Mechanical Engineering, University of Campinas – UNICAMP, 13083-970 Campinas, SP, Brazil article info Article history: Received 12 April 2013 Received in revised form 25 July 2013 Accepted 11 August 2013 Available online 26 September 2013 Keywords: Bagasse Cane trash Ethanol production Co-generation Fuel characterization abstract Sugarcane bagasse is the residue produced by mills after juice is extracted from sugarcane. Other important solid residues in the sugarcane-to-sugar-and-ethanol production chain are the leaves and tops of the stalks (together referred to as cane trash). Although it represents a significant portion of the energy in sugarcane, cane trash is currently left in the fields. This paper has described and analyzed how residues (bagasse and cane trash) are produced from sugarcane and their use as an energy source in the production of ethanol. Also, it presents a review of the physical properties and characteristics of bagasse and cane trash and estimate their energy potential. Bagasse and cane trash have similar fuel characteristics to other biomasses fuels. Special attention should be given to the characteristics of cane trash ash, which has higher fusibility and alkali levels than bagasse. A flowchart of a typical mill was described and the thermal and mechanical energy consumption at various stages of the production process was determined. Of the energy consumed as work, about 58% is accounted for by milling and juice extraction, and 33% by the generation of electricity for use in the plant. In a typical mill using steam generators operating at average pressure and temperature (22 bar, 300–360 1C), about 15% of the bagasse produced is surplus, and an average of 480 kg of steam is used per tonne of cane processed. An energy consumption analysis revealed that there was significant scope for reducing the amount of steam needed to operate the turbines in mills because of the low isentropic efficiencies identified. Cane trash, which is not yet used for energy production, also shows great energy potential because it is produced in similar quantities to bagasse, and its calorific value is only slightly lower. & 2013 Elsevier Ltd. All rights reserved. Contents 1. Introduction ........................................................................................................ 590 2. Methodologies ...................................................................................................... 591 3. Morphology of sugarcane ............................................................................................. 591 4. The harvesting process and cane trash production ......................................................................... 591 5. The milling process and bagasse production .............................................................................. 592 5.1. Preparation of sugarcane ........................................................................................ 593 5.2. Extraction of raw juice by milling................................................................................. 593 5.3. Extraction of raw juice by diffusion ............................................................................... 594 6. Characterization of bagasse and cane trash as fuel ......................................................................... 595 6.1. The morphology of bagasse Particles .............................................................................. 595 6.2. The density of bagasse ......................................................................................... 596 6.3. Chemical characterization of bagasse and cane trash ................................................................. 596 6.4. Proximate analysis and gross calorific value ........................................................................ 597 6.5. Thermogravimetric analysis ..................................................................................... 597 6.6. Analysis of ash ................................................................................................ 598 Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/rser Renewable and Sustainable Energy Reviews 1364-0321/$ - see front matter & 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.rser.2013.08.056 n Corresponding author. Tel.: þ55 19 3521 3373; fax: þ55 19 3289 3722. E-mail addresses: bizzo@fem.unicamp.br, waldirbizzo@gmail.com (W. Antonio Bizzo), lenco@actualis.com.br (P.C. Lenço), liar@fem.unicamp.br (D.J. Carvalho), jpsveiga@usp.br (J.P.S. Veiga). 1 Present adress: University of Cuiabá, Cuiabá, MT, Brazil. 2 Present adress: Luiz de Queiroz College of Agriculture, University of São Paulo, Piracicaba, SP, Brazil. Renewable and Sustainable Energy Reviews 29 (2014) 589–603