Sugarcane straw availability, quality, recovery and energy use: A literature review Manoel Regis L.V. Leal a , Marcelo V. Galdos a , Fa ´ bio V. Scarpare a , Joaquim E.A. Seabra a,b, *, Arnaldo Walter a,b , Camila O.F. Oliveira a a Laborato ´rio Nacional de Cie ˆncia e Tecnologia do Bioetanol e CTBE/CNPEM, Caixa Postal 6170, 13083-970 Campinas, Sa ˜o Paulo, Brazil b Faculdade de Engenharia Meca ˆ nica, Unicamp, Cidade Universita ´ria “Zeferino Vaz”, CEP 13083-860 Campinas, SP, Brazil article info Article history: Received 21 June 2012 Received in revised form 5 March 2013 Accepted 6 March 2013 Available online 13 April 2013 Keywords: Agricultural residues Bioenergy Ethanol Sustainability Litter abstract Sugarcane straw represents, under Brazilian conditions, approximately one third of the total primary energy of sugarcane in the field. Today, its use for energy is incipient and it is mostly wasted by either burning in the pre-harvest or left on the ground to decay. Besides its potential use as feedstock for energy production, there are several possible agronomic benefits of the straw blanket left on the ground such as soil protection against erosion, increase of soil organic carbon content, inhibition of weed growth, nutrient recycling and reduction of soil water losses, to name a few. The balance of the impacts and the economic and energetic value of the straw indicate that the amount of the straw left on the ground that could be considered optimal is dependent on the local conditions, agricultural prac- tices, characteristics of the straw and intended final use. This work is meant to shed some light into this subject to help the understanding of the importance of the various impacts of the straw blanket on the ground, the availability and quality of the straw, the economics of straw recovery and use and the main criteria for determining the amount of straw that can be recovered for bioenergy or biofuels production. ª 2013 Elsevier Ltd. All rights reserved. 1. Introduction Sugarcane has been cultivated for centuries and sugar pro- duction has driven the several world breeding programs that resulted in the so called noble cane varieties in commercial use today. Initially, sugar was a high value specialty but has long ago become one of the cheapest food calories due to the drastic reduction in production cost. Sugarcane is not only a high yield food crop, but has demonstrated to be also an excellent energy feedstock due to its high primary energy content per Mg of cane. The higher heating value (HHV) of whole sugarcane (including 140 kg of straw, dry basis) is 7.4 GJ per Mg of cane stalks (with 70% moisture content), based on the average Brazilian cane quality. The energy products ethanol and bagasse, however, represent only 2.2 GJ Mg -1 or less than 30% of the primary energy [1]. Bagasse (the industrial fibrous residue from the juice extraction) is practically all consumed in the mill boilers to provide for the mill energy demand, and the fiber in the sugarcane leaves and tops (straw, also known as trash) is normally burned in the pre-harvest. The practice of burning the sugarcane residues to facilitate harvest and transport operations has been widespread worldwide to reduce the cost of harvesting sugarcane, espe- cially in non-mechanized operations (i.e. manual harvesting). * Corresponding author. Laborato ´ rio Nacional de Cie ˆ ncia e Tecnologia do Bioetanol e CTBE/CNPEM, Caixa Postal 6170, 13083-970 Cam- pinas, Sa ˜ o Paulo, Brazil. Tel.: þ55 19 3521 3284. E-mail addresses: jseabra@fem.unicamp.br, jeaseabra@gmail.com (J.E.A. Seabra). Available online at www.sciencedirect.com http://www.elsevier.com/locate/biombioe biomass and bioenergy 53 (2013) 11 e19 0961-9534/$ e see front matter ª 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.biombioe.2013.03.007