Introduction Until recently bio fuels were held in high regard; they were renewable, exhibited large energy efficiencies and some had low costs. Most especially, bio fuels offered good opportunities for the reduction of greenhouse gas emissions from transport. In the last couple of years, however, a growing barrage of criticism – some no doubt politically motivated – introduced misgivings regarding the real contribution of bio fuels, among them, ethanol. In spite of the energy efficiency and of the low cost of ethanol from sugar cane, its sustainability has been challenged based on two kinds of effects, direct and indirect (UK Renewable Fuels Agency 2008). The direct effects stem from the incorporation of land for the production of sugar cane, resulting in habitat destruction (the case of the Amazon is often mentioned) and negative social impacts, especially dire working conditions. The indirect effects center on increasing food prices and the displacement of existing agricultural activities into uncultivated areas with negative impacts on biodiversity and on green house gas (GHG) savings.1