Showing papers in "Journal of Biobased Materials and Bioenergy in 2008"

Towards Standardization of Life-Cycle Metrics for Biofuels: Greenhouse Gas Emissions Mitigation and Net Energy Yield

Abstract: Despite a rapid worldwide expansion of the biofuel industry, there is a lack of consensus within the scientific community about the potential of biofuels to reduce reliance on petroleum and decrease greenhouse gas (GHG) emissions. Although life cycle assessment provides a means to quantify these potential benefits and environmental impacts, existing methods limit direct comparison within and between different biofuel systems because of inconsistencies in performance metrics, system boundaries, and underlying parameter values. There is a critical need for standardized life-cycle methods, metrics, and tools to evaluate biofuel systems based on performance of feedstock production and biofuel conversion at regional or national scales, as well as for estimating the net GHG mitigation of an individual biofuel production system to accommodate impending GHG-intensity regulations and GHG emissions trading. Predicting the performance of emerging biofuel systems (e.g., switchgrass cellulosic ethanol) poses additional challenges for life cycle assessment due to lack of commercial-scale feedstock production and conversion systems. Continued political support for the biofuel industry will be influenced by public perceptions of the contributions of biofuel systems towards mitigation of GHG emissions and reducing dependence on petroleum for transportation fuels. Standardization of key performance metrics such as GHG emissions mitigation and net energy yield are essential to help inform both public perceptions and public policy.

Microwave Pretreatment, Enzymatic Saccharification and Fermentation of Wheat Straw to Ethanol

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Nanocomposites from Regenerated Cellulose and Nanoclay

Abstract: Cut off the film Cut off the film Dried cellulose film Wet film of regenerated cellulose •Regenerated cellulose: nanocomposites matrix materials High mechanical properties Strong hydrogen bond Strong hydrophilic property Partially crystalline structure (~40%) Low processiblity •Montmorillonite (MMT): nanocomposites filler materials High Aspect ratio layered silicate Layer thickness: 1nm Lateral dimensions: 100~200nm Anionic and hydrophilic surface •N-methylmorpholine-N-oxide (NMMO) Hard to dissolve A specific solvent like NMMO is needed Strong N-O dipoles can substitute the intermolecular hydrogen bonds of cellulose NANOCOMPOSITES FROM REGENERATED CELLULOSE AND NANOCLAY Jihoon Lee and Yulin Deng Institute of Paper Science and Technology at Georgia Tech Motivation

Anaerobic biogas generation from sugar industry wastewaters in three-phase fluidized-bed bioreactor

Abstract: The studies are undertaken to develop an effective anaerobic continuous digestion process for biogas generation from sugar industry wastewaters using actively digested sludge from a sewage plant, in three-phase fluidized bed bioreactor. Attempts are made to optimize hydraulic retention time (HRT), initial feed pH, feed temperature and flow rate of feed (organic loading rate) for maximum production of methane gas and maximum removal of chemical oxygen demand (COD) and biological oxygen demand (BOD) of sugar industry wastewaters. The optimum conditions for the system are: digestion time, 8 h; initial pH of feed, 7.5; feed temperature, 40oC; feed flow rate, 14 L/ min with maximum organic loading rate (OLR), 39.513 kg COD m �3 h �1 . The organic loading rates (OLR) are calculated on the basis of COD inlet in the bioreactor at different flow rates. The maximum expansion of the bed is observed as 23.67 m at optimum feed flow rate of 14 L/ min. The maximum methane gas concentration is 63.56% ( v/v ) of the total biogas generation at optimum process parameters. The maximum biogas yield rate is 0.835 m 3 /kg COD m �3 h �1 with maximum methane gas yield rate of 0.530 m 3 /kg COD m �3 h �1 (63.56% v/v ) at optimum process parameters. The values for maximum reduction of COD and BOD are 76.82% ( w/w ) and 81.65% ( w/w ) with maximum OLR of 39.513 kg COD m �3 h �1 at optimum conditions.