Brazilian Biofuels Programmes from the WEL Nexus Perspective

Brazil’s biofuel programmes viewed from the WEL-nexus perspectiveissue, about 80% of the rivers are in critical, worrying or very worrying conditions regardingpotability (ANA, 2007). In this case, resources should be managed so that the potable waterresources are not entirely used for the expansion of sugar cane, for which water quality is notcritical, as it is for human consumption.4.3 EnergyIt is essential to evaluate the energy balance of a given product, in this case ethanol and biodiesel,in order to assess the sustainability of its production and usage. Testing the energybalance is even more important in relation to the WEL-nexus analysis.Energy and GHG balances are required to evaluate the net effects during the complete well-towheelcycle of ethanol, i.e. ethanol production from sugar cane and its use as fuel for transport(Macedo et al., 2004). The same rationale applies to bio-diesel.The advantage of biofuels displacing their fossil-fuel equivalents depends on the relativemagnitude of the input versus the savings of fossil fuels resulting from the biofuel use (Macedoet al., 2008). There are a couple of methodologies used for evaluating energy balance. Themost commonly used is the Life Cycle Assessment (LCA), a method for determining theenvironmental impact of a product (good or service) during its entire lifecycle from extractionof raw materials through manufacturing, logistics and use to scrapping and recycling (Luo etal., 2009). In the case of the energy balance, LCA in agriculture focuses primarily on nonrenewableenergy inputs in the product’s lifecycle, from the extraction of the natural resourceto the use and disposal of the product (Takahashi and Ortega, 2010).The LCA is based in the ratio of renewable energy output and fossil-fuel energy input related tothe components of the production and use of the biofuel. The evaluation of avoided emissionsdepends on the equivalences between the renewable fuel and the fossil fuels replaced; and ontheir respective lifecycle emissions (Macedo et al., 2008).Among the biofuels, ethanol is attracting most attention; large-scale production already existsin Brazil and it can be easily blended with gasoline to operate in spark ignition (SI) engines(Macedo et al., 2008). There are many different studies related to GHG emissions, energybalance and environmental issues involved in the ethanol production and use (Goldemberg etal., 2008a; Macedo et al., 2004, 2008; Luo et al., 2009). We will present a comprehensivereview of the existing literature for LCA of ethanol and use the results as a basis for the WELnexusanalysis for this biofuel.The lifecycle of the production of ethanol from sugar cane, with heat and electricity generationfrom bagasse using the current technology applied in Brazil, is presented in Figure 4.7.33