Oil products account for approximately 95 % of the energy used for transportation in the world in their various modes. The technological standards for the use of this energy source, which has been strongly disseminated in the world, developed over more than a century.

However, several liabilities accompany its hegemonic use, since the reduction of available stocks of this essential non-renewable resource (petroleum), pollution, and GHG emissions (Seabra 2008: 83).

Therefore, the continuation of fossil fuel energy resources use provides strate­gic and environmental drawbacks, seeing that the use of non-renewable sources is revealed as a way of releasing elements captured in a remote past, which expose the modern lifestyle to a not properly dimensioned future risk.

On the other hand, the production and the consumption of biofuel obtained from agricultural biomass (renewable resources) entails a GHG balance (CO2 eq.) close to neutrality. Thus, unlike fossil fuels, the biomass has sustainable features, since human systems capitalize on energy use with little interference in the GHG balance (ANEEL 2008; Macedo et al. 2008; Garcia 2011).

According to Table 10, the sugarcane has the best energy efficiency (9.3) among the different sources of biomass available in Brazil and it has the highest reduction percentage of GHG emissions (89 %). These indicators are much higher than those obtained by corn (US option) or beet (an option used in Europe).

When the Life Cycle Assessment (LCA) of some biofuels was performed, ethanol was highlighted due to the high percentage of GHG reduction, as depicted in Fig. 9.

Even though the options of energy production are within the renewable status, they are not free of interfering negatively on the environment. One of the most important liabilities is the interference in the soil and the formation of monocul­tures over large areas. However, these problems can be mitigated by techniques and processes that increase biomass productivity per area. An example of this is that Brazil produces 6,800 l of ethanol per hectare of sugarcane, while the USA produces 3,100 l/ha of maize (ANEEL 2008).

In Brazil, several crops have the potential to produce bioenergy, among them soy, sugarcane, castor bean, and palm oil. The cultivation of sugarcane has been highlighted in the production of ethanol. With a focus on increasing productivity, the mills have opted for mechanical harvesting, including suitability for the cur­rent legislation which restricts fires of sugarcane straw for the crop.

Another element of this sustainable supply chain is the use of bagasse to pro­duce electricity through thermal power plants (ANEEL 2008).

The techniques and processes evolution and R&D also contribute to the increased efficiency in the various stages of the production process, such as har­vesting sugarcane in Brazil, which is abandoning the straw burning for the harvest and better studies about the emission levels in the various stages of production and processing of this biomass (Table 11).