Brazilian Biofuels Programmes from the WEL Nexus Perspective

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Brazil’s biofuel programmes viewed from the WEL-nexus perspectiveFigure 4.7 Lifecycle of production and use of ethanol from sugar caneSource: Luo et al., 2009.Macedo et al. (2008) developed the energy balance and GHG emissions reductions of theproduction and use of ethanol from sugar cane in Brazil in 2008 using the average conditionsin 2005/2006. The situation for a conservative 2020 scenario was also evaluated. The dataused for the fossil energy consumption in the sugar cane production, harvesting andtransportation and the fossil energy consumption in the production of ethanol are presented inTable 4.6.34
Brazil’s biofuel programmes viewed from the WEL-nexus perspectiveTable 4.6 Energy balance of ethanolFossil energy consumption in sugar cane production, harvesting and transportation (MJ tc -1 )Item 2005/06 Scenario 2020Agricultural operations 13.3 14.8Harvesting 33.3 46.9Sugar cane transportation 38.6 44.8Inputs transportation 10.9 13.5Other activities 38.5 44.8Fertilisers 52.7 40.0Lime, herbicides, insecticides 12.1 11.1Seeds 5.9 6.6Machinery 6.8 15.5Total 210.2 238.0Fossil energy consumption in the production of ethanol (MJ tc -1 )Item 2005/06 Scenario 2020Chemicals and lubricants 19.2 19.7Building 0.5 0.5Equipments 3.9 3.9Total 23.6 24.0Energy balance, external flows (MJ tc -1 )2005/06 Scenario 2020Fossil inputSugar cane production/transportation 210.2 238.0Production of ethanol 23.6 24.0Total fossil input 233.8 262.0Renewable outputEthanol 1926.4 2060.3Bagasse surplus 176.0 0.0Electricity surplus 82.8 972.0Total renewable output 2185.2 3032.3Renewable output/fossil input (ethanol + bagasse + electricity) 9.3 11.6Source: The authors based on Macedo et al., 2008.Table 4.6 suggests that a considerable increase is expected in the fossil-fuel energyconsumption in the 2020 scenario (from 210.2 MJ in 2008 to 238 MJ in 2020), mainly due todiesel consumption associated to the growth of mechanical harvesting, trash recovering andincrease in the use of machinery (this item more than doubles for the 2020 scenario) (Macedoet al., 2008). Burning cane fields, still a common practice in Brazil, is a major concern becauseof the associated environmental and health hazards. This issue is being treated by theenvironmental agencies and will probably be resolved in the medium term through laws andagreements between government authorities and the sugar cane industry, increasingmechanical harvesting and the use of machinery. For example, in São Paulo, State Law no.11.241/2002 forbids the burning of straw for the purpose of manual sugar cane harvestingfrom 2021 (IEA, 2002).Higher use of residues in ferti-irrigation would significantly reduce the demand for mineralfertilisers. Macedo et al. (2004) also explain the slight changes in energy consumption for theproduction of ethanol (Table 4.6) for the 2020 scenario by the improvement of ethanol yield.The results of Macedo et al. (2008), as well as other results found in the literature review,show that the energy balance of ethanol is extremely positive. Fossil energy ratio was 9.3 for2005/2006 and may reach 11.6 in 2020 using existing commercial technologies (ibid.).Urquiaga et al. (2004) found the value of 8.06 for the fossil energy ratio for ethanol in 2004.According to Coelho et al. (2006), the production costs of ethanol from sugar cane are low notonly because of geographic conditions but also because of the favourable energy balance.35
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Brazilian Biofuels Programmes from the WEL Nexus Perspective

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