It is expected that the newer forms of biofuels, including ethanol, could really be cleaner and more efficient than traditional forms of biofuels. Favorable CO2 bal­ance and other emissions reduction when bioethanol is burned in engines could help mitigate global climate change. Even if aldehyde emissions slowly increase, the use of catalysts normally destroys this contaminant easily.

Biofuel production may introduce new environmental risks and new chal­lenges for the producing countries. This will particularly be the case when natural resource constraints cause greater trade-offs between food production and biofuel production. Respect for the rainforests and all protected areas should be the core of any regulations and policies. There are serious concerns in Latin America and Africa for the deforestation activities.

Fuel ethanol production includes the generation of a large quantity of residues. Effluent treatment will always be an important topic of research. Reduction of air pollution must not cause the increase of soil or water contamination. There are cases of noncompatibility of stillages in Colombia with the soil quality in the sugarcane plantations.

Using ethanol as a vehicle fuel has the potential to reduce nonrenewable energy consumption and greenhouse gas (GHG) emissions. However, acidification, eutrophication, and photochemical smog could increase when compared to using gasoline as liquid fuel. This information should be analyzed for every feedstock, location, and blending to avoid confusion about the environmental performance of fuel ethanol projects.

Life cycle analysis (LCA) enables one to investigate environmental perfor­mance of fuel ethanol used in different concentrations in gasoline. This analysis can include a serious waste reduction (WAR) algorithm for numerical calculation of potential environmental impacts. This type of strategy is an important compo­nent for identifying practices that will help to ensure that a renewable fuel, such as ethanol, may be produced in a sustainable manner.

The dominant factor determining most environmental impacts, such as green­house gas emissions, acidification, eutrophication, and photochemical smog for­mation, is soil-related nitrogen losses. Usually the source of soil nitrogen can include fertilizers.

However, the most important discussion about environmental advantages of fuel ethanol use is the fact that fluxes of avoided GHG emissions from this biofuel production system are found to be much less than from afforestation or reforesta­tion. In countries like Brazil, Colombia, and Peru, where deforestation is advanc­ing significantly, this issue is a real concern and should be watched closely by the entire world (Table 13.4).

[1] Filter paper units (FPU) allow the indirect quantification of enzymatic activity of cellulases. One FPU is equivalent to the cellulase amount needed to form 1 pmol glucose in one minute measured as reducing sugars (or to form 0.10 mg glucose in one minute) during the cellulose hydrolysis reac­tion employing as the substrate Whatman No. 1 paper filter under determined conditions (pH = 4.8, 0.05 M sodium citrate buffer, 50°C). See Ghose (1987).