Benefits of sugarcane for ethanol
The reasons why we choose ethanol from sugarcane as the most promising biofuels are illustrated below. Firstly, the balance of GHG emissions of sugarcane ethanol is the best among all biofuels currently produced (Macedo et al., 2008; Cerri et al., 2009; Oliveira et al., 2005). As reviewed in several studies, bioethanol based on sugarcane can achieve greenhouse gas reductions of more than 80% compared to fossil fuel use (Macedo et al., 2008). Figure 2 (BNDES, 2008) showed correspond to the consumption of ethanol produced from maize (USA), from wheat (Canada and Europe) and from sugarcane (produced in Brazil and consumed in Brazil or in Europe). Sugarcane ethanol is much better than ethanol from maize and wheat (a maximum of 35%) in case of the avoided emissions.
Secondly, as we known, cropland is very limited for planting in China. So it is very important that the land use is keeping in a high efficient level. Ethanol from sugarcane is the most productive among different crops. The fortunate experience of ethanol use in Brazil may also be coupled with a superior sucrose yield and a higher potential of biomass production of sugarcane — an average of 87 tons per hectare in South Central Brazil — than observed in other crops. As shown in figure 3, only beets can be compared with sugarcane in terms of ethanol production per cultivated hectare. However, the industrial process of ethanol production from beets depends on an external power input (electricity and fuel) while sugarcane electricity is provided by bagasse burning at the mill. (BNDES, 2008). Ethanol produced from sugarcane is the biofuel with the best energy balance (see tablel). This can be illustrated as the ratio between renewable products and the energy input as fossil fuel for Brazilian sugarcane ethanol is 9.3 (compared with 1.2-1.4 in the case of ethanol produced from American maize, and approximately 2.0 in the case of ethanol produced from European wheat). Apart from these above, other environmental impacts of the sugarcane sector, such as water consumption, contamination of soils and water shields due
to the use of fertilizers and chemicals, and loss of biodiversity, are less important in comparison to other crops (Watanabe, 2009). Above in all, Sugarcane is by far the best alternative from the economical, energy and environmental point of view, for bio-fuel production.
Feedstock Energy ratio
Table 1. Comparison of different feedstock for biofuel production. Source:BNDES(2008)