Publications

Abstract not provided.

Abstract not provided.

In the current study, processes to produce either ethanol or a representative fatty acid ethyl ester (FAEE) via the fermentation of sugars liberated from lignocellulosic materials pretreated in acid or alkaline environments are analyzed in terms of economic and environmental metrics. Simplified process models are introduced and employed to estimate process performance, and Monte Carlo analyses were carried out to identify key sources of uncertainty and variability. We find that the near-term performance of processes to produce FAEE is significantly worse than that of ethanol production processes for all metrics considered, primarily due to poor fermentation yields and higher electricity demands for aerobic fermentation. In the longer term, the reduced cost and energy requirements of FAEE separation processes will be at least partially offset by inherent limitations in the relevant metabolic pathways that constrain the maximum yield potential of FAEE from biomass-derived sugars.

Recent estimates of fuel consumption in construction projects are highly variable. Lack of standards for reporting at both the equipment and project levels make it difficult to quantify the magnitude of fuel consumption and the associated opportunities for efficiency improvements in construction projects. In this study, we examined clusters of Environmental Impact Reports for seemingly similar construction projects in California. We observed that construction projects are not characterized consistently by task or equipment. We found wide variations in estimates for fuel use in terms of tasks, equipment, and overall projects, which may be attributed in part to inconsistencies in methodology and parameter ranges. Our analysis suggests that standardizing fuel consumption reporting and estimation methodologies for construction projects would enable quantification of opportunities for efficiency improvements at both the equipment and project levels. With increasing emphasis on reducing fossil fuel consumption, it will be important to quantify opportunities to increase fuel efficiency, including across the construction sector. © 2012 Elsevier Ltd.

Abstract not provided.

Abstract not provided.

This report presents a system dynamics based model of the supply-demand interactions between the US light-duty vehicle (LDV) fleet, its fuels, and the corresponding primary energy sources through the year 2050. An important capability of our model is the ability to conduct parametric analyses. Others have relied upon scenario-based analysis, where one discrete set of values is assigned to the input variables and used to generate one possible realization of the future. While these scenarios can be illustrative of dominant trends and tradeoffs under certain circumstances, changes in input values or assumptions can have a significant impact on results, especially when output metrics are associated with projections far into the future. This type of uncertainty can be addressed by using a parametric study to examine a range of values for the input variables, offering a richer source of data to an analyst.The parametric analysis featured here focuses on a trade space exploration, with emphasis on factors that influence the adoption rates of electric vehicles (EVs), the reduction of GHG emissions, and the reduction of petroleum consumption within the US LDV fleet. The underlying model emphasizes competition between 13 different types of powertrains, including conventional internal combustion engine (ICE) vehicles, flex-fuel vehicles (FFVs), conventional hybrids(HEVs), plug-in hybrids (PHEVs), and battery electric vehicles(BEVs).We find that many factors contribute to the adoption rates of EVs. These include the pace of technological development for the electric powertrain, battery performance, as well as the efficiency improvements in conventional vehicles. Policy initiatives can also have a dramatic impact on the degree of EV adoption. The consumer effective payback period, in particular, can significantly increase the market penetration rates if extended towards the vehicle lifetime.Widespread EV adoption can have noticeable impact on petroleum consumption and greenhouse gas(GHG) emission by the LDV fleet. However, EVs alone cannot drive compliance with the most aggressive GHG emission reduction targets, even as the current electricity source mix shifts away from coal and towards natural gas. Since ICEs will comprise the majority of the LDV fleet for up to forty years, conventional vehicle efficiency improvements have the greatest potential for reductions in LDV GHG emissions over this time.These findings seem robust even if global oil prices rise to two to three times current projections. Thus,investment in improving the internal combustion engine might be the cheapest, lowest risk avenue towards meeting ambitious GHG emission and petroleum consumption reduction targets out to 2050.3 Acknowledgment The authors would like to thank Dr. Andrew Lutz, Dr. Benjamin Wu, Prof. Joan Ogden and Dr. Christopher Yang for their suggestions over the course of this project. This work was funded by the Laboratory Directed Research and Development program at Sandia National Laboratories.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

A parametric analysis is used to examine the supply demand interactions between the US light-duty vehicle (LDV) fleet, its fuels, and the corresponding primary energy sources through 2050. The analysis emphasizes competition between conventional internal combustion engine (ICE) vehicles, including hybrids, and electric vehicles (EVs), represented by both plug-in hybrid and battery electric vehicles. We find that EV market penetration could double relative to our baseline case with policies to extend consumers' effective payback period to 7 years. EVs can also reduce per vehicle petroleum consumption by up to 5% with opportunities to increase that fraction at higher adoption rates. However, EVs have limited ability to reduce LDV greenhouse gas (GHG) emissions with the current energy source mix. Alone, EVs cannot drive compliance with the most aggressive GHG emission reduction targets, even if the electricity grid shifts towards natural gas powered sources. Since ICEs will dominate the LDV fleet for up to 40 years, conventional vehicle efficiency improvements have the greatest potential for reductions in LDV GHG emissions and petroleum consumption over this time. Specifically, achieving fleet average efficiencies of 72. mpg or greater can reduce average GHG emissions by 70% and average petroleum consumption by 81%. © 2012 Elsevier Ltd.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.

Abstract not provided.