This post continues my discussion of biofuels from Part 1.

Brazil contains many of the world’s biodiversity hotspots, as well as one of the most important CO­₂-sinks in the form of rainforests. As the second largest sugarcane grower in the world, Brazil’s biofuel production relies heavily on sugarcane ethanol, which has one of the highest savings in GHG emissions compared to fossil fuels. However, increasing sugarcane production is not sustainable in the long-term if one of Brazil’s goals is to curtail GHG emissions, since growing more sugarcane means cutting down more rainforest. Instead, second- and third-generation (advanced) biofuels should be considered viable options for replacing sugarcane, or at least strongly supplementing it.

These biofuels, such as hydrocarbon fuels converted from biomass to liquid (BtL), biogas, or ethanol made from cellulose, are made from feedstock rich in cellulose like grass and wood. Advanced biofuels generally have better environmental profiles than first generation biofuels like sugarcane ethanol; given that sugarcane ethanol can yield between 80% and greater than 100% reductions in GHG emissions, advanced biofuels have significant potential. Brazil’s sugarcane plantations covered 9 million hectares (~22 million acres) in 2008, out of the total arable 60 million or so hectares (~148 million acres) of land. Since cattle and soybeans already occupy much of this arable land, it is likely that expansion of sugarcane will have to occur in high-biodiversity areas such as savannah or rainforest. Loss of these rich ecosystems to agriculture will emit far more carbon than the fossil fuels sugarcane saves, and sugarcane production today already pollutes the air: burning sugarcane fields before manual harvest is a practice that increases worker safety and convenience, but causes acid rain and high GHG emission. Switching to machine harvesting, and perhaps using equipment that runs on local biofuels, is advisable. Another current sugarcane production practice that should change is excessive vinasse fertilization—current laws regarding its effects on water pollution must be more strictly enforced. Vinasse is a leftover byproduct of the sugarcane after it has been processed. The high organic content of the sugarcane leftovers has potential as material for biogas digestion, which would reduce waste, maximize energy, and minimize carbon emissions. This sort of energy recovery and cascading use of sugarcane biomass may propel the crop, which Brazil has so heavily invested in, to advanced biofuel status. If its production and processing techniques are carefully improved and monitored, GHG emission savings could grow accordingly, giving Brazil the opportunity to be a leader in biofuels.

But the country cannot sacrifice its natural ecosystems, which have high value in a wealth of industries (e.g. tourism, pharmaceuticals, carbon credits), for cropland expansion. The agro-ecological zoning employed in the Amazon to limit deforestation must continue, and research on maximizing production on current, degraded, and marginal lands should take priority. Diversification of biofuels, such as using biogas from cattle waste and biodiesel from soya, may help reduce the negative effects of land conversion like biodiversity loss and GHG emission.

Sources:

Howarth, R.W., S. Bringezu, M. Bekunda, C. de Fraiture, L. Maene, L. Martinelli, O. Sala. 2009. Rapid assessment on biofuels and environment: overview and key findings. Pages 1-13 in R.W. Howarth and S. Bringezu (eds), Biofuels: Environmental Consequences and Interactions with Changing Land Use. Proceedings of the Scientific Committee on Problems of the Environment (SCOPE) International Biofuels Project Rapid Assessment, 22-25 September 2008, Gummersbach Germany. Cornell University, Ithaca NY, USA.

Bringezu, S., H. Shultz, M. O’Brien, L. Kauppi, R. W. Howarth.  2009. Towards sustainable production and use of resources: assessing biofuels. Report to the United Nations Environment Programme. 36 pp. Paris, France.