Review Paper on Nitrogen and Biofuelshttp://www.springerlink.com/content/l774517j664v027r/
In order to evaluate whether a particular biofuel is sustainable, the major factors that are often considered are (1) the net energy yield (i.e. the difference in the energy derived from the burning of the biofuel for transport or other uses and the energy used to produce it), (2) the greenhouse gas (GHG) emissions impact in terms of net carbon dioxide released (analogous to the "carbon footprint"), (3) food security impacts, (4) biodiversity impacts, and (5) the water-use impacts. Life Cycle Analysis (LCA) is the often-used tool to assess biofuel sustainability, and this usually factors-in the previously mentioned considerations.
Recently, an international team of scientists, headed by researchers from Energy Research Centre of The Netherlands, the VU Free University of Amsterdam, and the Netherlands Environmental Assessment Agency, report that large scale biofuel feedstock cultivations may also exert a major impact on the nitrogen cycle. In their paper which reviewed the state of knowledge on nitrogen and biofuels, they mention the possibility that large scale biomass cultivations for biofuel production could accelerate the nitrogen cycle, through (1) increased fertilizer use resulting in losses to the environment and (2) additional emissions of oxidized nitrogen (a gas with similar adverse impacts as other greenhouse gases).
In their review paper, an overview of "nitrogen-relevant processes in relation to biomass for energy use was presented". They also attempted to quantify the major nitrogen issues based on literature values, and discussed whether current LCA activities address the major nitrogen issues. The full review paper is published in the journal, Nutrient Cycling in Agroecosystems (URL above).
This article is part of the Crop Biotech Update, a weekly summary of world developments in agri-biotech for developing countries, produced by the Global Knowledge Center on Crop Biotechnology, International Service for the Aquisition of Agri-Biotech Applications SEAsiaCenter (ISAAA)