Utilizing domestically produced cellulose-derived ethanol for the light-duty vehicle fleet can potentially improve the environmental performance and sustainability of the transport and energy sectors of the economy. A life cycle assessment model was developed to examine environmental implications of the production and use of ethanol in automobiles in Ontario, Canada. The results were compared to those of low-sulfur reformulated gasoline (RFG) in a functionally equivalent automobile. Two time frames were evaluated, one near-term (2010), which examines converting a dedicated energy crop (switchgrass) and an agricultural residue (corn stover) to ethanol; and one midterm (2020), which assumes technological improvements in the switchgrass-derived ethanol life cycle. Near-term results show that, compared to a RFG automobile, life cycle greenhouse gas (GHG) emissions are 57% lower for an E85-fueled automobile derived from switchgrass and 65% lower for ethanol from corn stover, on a grams of CO2 equivalent per kilometer basis. Corn stover ethanol exhibits slightly lower life cycle GHG emissions, primarily due to sharing emissions with grain production. Through projected improvements in crop and ethanol yields, results for the mid-term scenario show that GHG emissions could be 25-35% lower than those in 2010 and that, even with anticipated improvements in RFG automobiles, E85 automobiles could still achieve up to 70% lower GHG emissions across the life cycle.
A comprehensive contemporary cycle for stocks and
flows of copper is characterized and presented, incorporating
information on extraction, processing, fabrication and
manufacturing, use, discard, recycling, final disposal, and
dissipation. The analysis is performed on an annual
basis, ca. 1994, at three discrete governmental unit levels−56 countries or country groups that together comprise
essentially all global anthropogenic copper stocks and flows,
nine world regions, and the planet as a whole. Cycles
for all of these are presented and discussed, and a “best
estimate” global copper cycle is constructed to resolve
aggregation discrepancies. Among the most interesting results
are (1) transformation rates and recycling rates in
apparently similar national economies differ by factors of
two or more (country level); (2) the discard flows that
have the greatest potential for copper recycling are those
with low magnitude flows but high copper concentrationselectronics, electrical equipment, and vehicles (regional level);
(3) worldwide, about 53% of the copper that was discarded
in various forms was recovered and reused or recycled
(global level); (4) the highest rate of transfer of discarded
copper to repositories is into landfills, but the annual
amount of copper deposited in mine tailings is nearly as
high (global level); and (5) nearly 30% of copper mining
occurred merely to replace copper that was discarded. The
results provide a framework for similar studies of other
anthropogenic resource cycles as well as a basis for
supplementary studies in resource stocks, industrial resource
utilization, waste management, industrial economics, and
environmental impacts.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.