Environmental implications of jatropha biofuel from a silvi-pastoral production system in central-west Brazil.

We present a life cycle assessment of synthetic paraffinic kerosene produced from Jatropha curcas. The feedstock is grown in an intercropping arrangement with pasture grasses so that Jatropha is coproduced with cattle. Additional innovations are introduced including hybrid seeds, detoxification of jatropha seedcake, and cogeneration. Two fuel pathways are examined including a newly developed catalytic decarboxylation process. Sensitivities are examined including higher planting density at the expense of cattle production as well as 50% lower yields. Intercropping with pasture and detoxifying seedcake yield coproducts that are expected to relieve pressure on Brazil's forests and indirectly reduce environmental impacts of biofuel production. Other innovations also reduce impacts. Results of the baseline assessment indicate that innovations would reduce impacts relative to the fossil fuel reference scenario in most categories including 62-75% reduction in greenhouse gas emissions, 64-82% reduction in release of ozone depleting chemicals, 33-52% reduction in smog-forming pollutants, 6-25% reduction in acidification, and 60-72% reduction in use of nonrenewable energy. System expansion, which explicitly accounts for avoided deforestation, results in larger improvements. Results are robust across allocation methodologies, improve with higher planting density, and persist if yield is reduced by half.

Criticality of the geological copper family.

Because modern technology depends on reliable supplies of a wide variety of materials, and because of increasing concern about those supplies, a comprehensive methodology has been created to quantify the degree of criticality of the metals of the periodic table. In this paper, we apply this methodology to the elements of the geological copper family: Cu, As, Se, Ag, Te, and Au. These elements are technologically important, but show a substantial variation in different factors relating to their supply risk, vulnerability to supply restriction, and environmental implications. Assessments are made on corporate, national, and global levels for year 2008. Evaluations of each of the multiple indicators are presented and the results plotted in "criticality space", together with Monte Carlo simulation-derived "uncertainty cloud" estimates for each of the aggregated evaluations. For supply risk over both the medium term and long term, As is the highest risk of the six metals, with Se and Ag nearly as high. Gold has the most severe environmental implications ranking. Vulnerability to supply restriction (VSR) at the corporate level for an invented solar cell manufacturing firm shows Se, Te, and Cu as approximately equal, Cu has the highest VSR at the national level, and Cu and Au have the highest VSRs at the global level. Criticality vector magnitudes are greatest at the global level for As (and then Au and Ag) and at the national level for As and Au; at the corporate level, Se is highest with Te and Cu lower. An extension of this work, now in progress, will provide criticality estimates for several different development scenarios for the period 2010-2050.