ALBERT

Description: Due to climate change and energy security concerns, bioenergy products and systems are becoming increasingly important, and Life Cycle Assessment (LCA) can provide a better understanding of their carbon efficiency. In this study, we used a cradle-to-grave LCA to analyze the carbon efficiency of a cottonwood-switchgrass agroforest system grown on agriculturally marginal soils on three sites established in 2009 in the Lower Mississippi Alluvial Valley (LMAV). A complete carbon inventory was done for both the agroforestry bioenergy system and a control cropping system that rotated soybeans and grain sorghum. Three years after establishment, the cottonwood sequestered the highest amount of carbon in dead roots, live roots, and surface residues (3222 kg ha−1) and the switchgrass sequestered the highest amount of carbon in above-ground biomass (4233 kg ha−1). The maximum carbon was emitted (1733 kg ha−1) from the soybean/grain sorghum rotation production system. The carbon emission during production was not statistically different for the bioenergy crops. Carbon emission from both bioenergy crops were significantly different compared to traditional agricultural crops. At the end of the third growing season, cottonwood showed the best performance in the net (6.2) and gross (11.8) ratios of carbon balance. The gross ratio of carbon by switchgrass (11.6) was comparable to cottonwood, but the net ratio was approximately 50% (3.3). The net and gross ratios of carbon balance were positive for the control cropping system as well, 1.2 and 2.2 respectively. Carbon emission from the traditional agricultural production system was at least 234% higher compared to the dedicated bioenergy production system. It was evident that bioenergy crops provide a more environmentally efficient practice in terms of carbon balance than the traditional agricultural practice in the Lower Mississippi alluvial Valley.

Description: Wood-based bioenergy development could play a vital role in attaining energy independence, reducing carbon emissions, and ensuring rural prosperity in the United States. An understanding of policies supporting wood-based bioenergy development coupled with the current status of production of various wood-based bioenergy products would better the prospects of wood-based bioenergy development in the United States. An understanding of the economic feasibility, social acceptability, and environmental externalities would contribute to effective policy prescriptions for establishing the US bioeconomy. Based on a comprehensive review of existing studies, we show that the heat and electricity derived from woody feedstocks that would prevail in the future as a commercial-level conversion technology for wood-based ethanol production are still under development. Society in general is positive about the use of woody feedstocks for bioenergy development. The production cost of wood-based ethanol and electricity generation has not reduced over time, indicating a need for targeted policy support focusing on sharing the production cost of wood-based bioenergy products. Wood-based bioenergy development could meet the need for sustainable energy production without affecting existing roundwood markets with the advent of advanced silvicultural treatments and efficient biotechnologies.