Andrew Burnham

Life-Cycle Greenhouse Gas Emissions of Shale Gas, Natural Gas, Coal, and Petroleum

The technologies and practices that have enabled the recent boom in shale gas production have also brought attention to the environmental impacts of its use. It has been debated whether the fugitive methane emissions during natural gas production and transmission outweigh the lower carbon dioxide emissions during combustion when compared to coal and petroleum. Using the current state of knowledge of methane emissions from shale gas, conventional natural gas, coal, and petroleum, we estimated up-to-date life-cycle greenhouse gas emissions. In addition, we developed distribution functions for key parameters in each pathway to examine uncertainty and identify data gaps such as methane emissions from shale gas well completions and conventional natural gas liquid unloadings that need to be further addressed. Our base case results show that shale gas life-cycle emissions are 6% lower than conventional natural gas, 23% lower than gasoline, and 33% lower than coal. However, the range in values for shale and conventional gas overlap, so there is a statistical uncertainty whether shale gas emissions are indeed lower than conventional gas. Moreover, this life-cycle analysis, among other work in this area, provides insight on critical stages that the natural gas industry and government agencies can work together on to reduce the greenhouse gas footprint of natural gas.

Well-To-Wheels Energy Use and Greenhouse Gas Emissions of Plug-in Hybrid Electric Vehicles

Researchers at Argonne National Laboratory expanded the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model and incorporated the fuel economy and electricity use of alternative fuel/vehicle systems simulated by the Powertrain System Analysis Toolkit (PSAT) to conduct a well-to-wheels (WTW) analysis of energy use and greenhouse gas (GHG) emissions of plug-in hybrid electric vehicles (PHEVs). The WTW results were separately calculated for the blended charge-depleting (CD) and charge-sustaining (CS) modes of PHEV operation and then combined by using a weighting factor that represented the CD vehicle-miles-traveled (VMT) share. As indicated by PSAT simulations of the CD operation, grid electricity accounted for a share of the vehicles total energy use, ranging from 6% for a PHEV 10 to 24% for a PHEV 40, based on CD VMT shares of 23% and 63%, respectively. In addition to the PHEVs fuel economy and type of on-board fuel, the marginal electricity generation mix used to charge the vehicle impacted the WTW results, especially GHG emissions. Three North American Electric Reliability Corporation regions (4, 6, and 13) were selected for this analysis, because they encompassed large metropolitan areas (Illinois, New York, and California, respectively) and provided a significant variation of marginal generation mixes. The WTW results were also reported for the U.S. generation mix and renewable electricity to examine cases of average and clean mixes, respectively. For an all-electric range (AER) between 10 mi and 40 mi, PHEVs that employed petroleum fuels (gasoline and diesel), a blend of 85% ethanol and 15% gasoline (E85), and hydrogen were shown to offer a 40-60%, 70-90%, and more than 90% reduction in petroleum energy use and a 30-60%, 40-80%, and 10-100% reduction in GHG emissions, respectively, relative to an internal combustion engine vehicle that used gasoline. The spread of WTW GHG emissions among the different fuel production technologies and grid generation mixes was wider than the spread of petroleum energy use, mainly due to the diverse fuel production technologies and feedstock sources for the fuels considered in this analysis. The PHEVs offered reductions in petroleum energy use as compared with regular hybrid electric vehicles (HEVs). More petroleum energy savings were realized as the AER increased, except when the marginal grid mix was dominated by oil-fired power generation. Similarly, more GHG emissions reductions were realized at higher AERs, except when the marginal grid generation mix was dominated by oil or coal. Electricity from renewable sources realized the largest reductions in petroleum energy use and GHG emissions for all PHEVs as the AER increased. The PHEVs that employ biomass-based fuels (e.g., biomass-E85 and -hydrogen) may not realize GHG emissions benefits over regular HEVs if the marginal generation mix is dominated by fossil sources. Uncertainties are associated with the adopted PHEV fuel consumption and marginal generation mix simulation results, which impact the WTW results and require further research. More disaggregate marginal generation data within control areas (where the actual dispatching occurs) and an improved dispatch modeling are needed to accurately assess the impact of PHEV electrification. The market penetration of the PHEVs, their total electric load, and their role as complements rather than replacements of regular HEVs are also uncertain. The effects of the number of daily charges, the time of charging, and the charging capacity have not been evaluated in this study. A more robust analysis of the VMT share of the CD operation is also needed.

Impacts of Vehicle Weight Reduction via Material Substitution on Life-Cycle Greenhouse Gas Emissions

This study examines the vehicle-cycle and vehicle total life-cycle impacts of substituting lightweight materials into vehicles. We determine part-based greenhouse gas (GHG) emission ratios by collecting material substitution data and evaluating that alongside known mass-based GHG ratios (using and updating Argonne National Laboratorys GREET model) associated with material pair substitutions. Several vehicle parts are lightweighted via material substitution, using substitution ratios from a U.S. Department of Energy report, to determine GHG emissions. We then examine fuel-cycle GHG reductions from lightweighting. The fuel reduction value methodology is applied using FRV estimates of 0.15-0.25, and 0.25-0.5 L/(100km·100 kg), with and without powertrain adjustments, respectively. GHG breakeven values are derived for both driving distance and material substitution ratio. While material substitution can reduce vehicle weight, it often increases vehicle-cycle GHGs. It is likely that replacing steel (the dominant vehicle material) with wrought aluminum, carbon fiber reinforced plastic (CRFP), or magnesium will increase vehicle-cycle GHGs. However, lifetime fuel economy benefits often outweigh the vehicle-cycle, resulting in a net total life-cycle GHG benefit. This is the case for steel replaced by wrought aluminum in all assumed cases, and for CFRP and magnesium except for high substitution ratio and low FRV.

Vehicle-Cycle Energy and Emission Effects of Conventional and Advanced Vehicles

A vehicle-cycle module of the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model has been developed at Argonne National Laboratory. The fuel-cycle GREET model has been published extensively and contains data on fuelcycles and vehicle operation. The vehicle-cycle module evaluates the energy and emission effects of vehicle material recovery and production, vehicle component fabrication, vehicle assembly, and vehicle disposal/recycling. The addition of the vehiclecycle module to the GREET model provides a comprehensive lifecycle-based approach to compare energy use and emissions of conventional vehicle technologies and advanced vehicle technologies such as hybrid electric vehicles and fuel cell vehicles. Using the newly developed vehicle-cycle module, this paper evaluates on a vehicle-cycle basis the energy use, greenhouse gas emissions, and selected air pollutant emissions of a mid-size passenger car with the following powertrain systems — internal combustion engine, internal combustion engine with hybrid configuration, and fuel cell with hybrid configuration. We found that the production of materials accounts for a majority of the vehicle-cycle energy use and emissions of all the vehicles examined. The energy use and greenhouse gas emissions increase for the advanced powertrain vehicles compared to the internal combustion engine vehicles, due to the use of energy-intensive materials in the fuel cell system of the fuel cell vehicle and the increased use of aluminum in both the hybrid electric vehicle and the fuel cell vehicle. In addition, the use of materials such as aluminum and carbon fiber composites increases the energy use and greenhouse gas emissions of lightweight vehicles. Furthermore, in order to put vehicle-cycle results into a broad perspective, the fuel-cycle GREET model is used in conjunction with the vehicle-cycle module to estimate total energy-cycle results. Materials used to reduce the weight of a vehicle help improve fuel economy, and reduce the energy use and GHG emissions of the fuel-cycle and vehicle operation stages; however, production of lightweight materials is energy-intensive compared to production of conventional materials. However, when examining energy use and emissions on the total energy-cycle basis, our simulations show that in terms of reducing total energy use and emissions, there can be a significant net benefit from substituting lightweight materials.

Life-Cycle Analysis of Production and Recycling of Lithium Ion Batteries

This paper discusses what is known about the life-cycle burdens of lithium ion batteries. Constituent-material production and the subsequent manufacturing of batteries are emphasized. Of particular interest is estimation of the impact of battery material recycling on battery manufacturing. Because some materials come from comparatively less plentiful resources, the recycling of lithium ion batteries and the potential impact on battery-production life-cycle burdens are discussed. This effort represents the early stage of lithium ion battery life-cycle analysis, in which processes are characterized preparatory to detailed data acquisition. Notwithstanding the lack of data on production of battery materials, it is estimated that the energy use and greenhouse gas emissions associated with battery manufacturing make up only a small percentage of a plug-in hybrid vehicles total life-cycle energy use. Further, the recycling of battery materials potentially can significantly reduce the material production energy.

INTRODUCTION: The Technology and Policy of Hydraulic Fracturing and Potential Environmental Impacts of Shale Gas Development

The development of large-scale shale gas production has been described as a game-changer for the US energy market and has generated interest in expanding the use of natural gas in sectors such as electricity generation and transportation. This development has been made possible by improvements in drilling technologies—specifically utilizing hydraulic fracturing in conjunction with horizontal drilling—that have enabled the production of natural gas from unconventional formations. However, the environmental implications of natural gas production and its use have been called into question. Environmental impacts associated with shale gas development can occur at the global and local levels and include impacts to climate, local air quality, water availability, water quality, seismic events, and the local community. A variety of technologies and practices are available to operators to reduce these impacts. Policies are currently under development at the federal, state, and local level to mitigate environmental impacts. In this document, we discuss the technologies involved in shale gas production, the potential abiotic impacts of shale gas production with an emphasis on air and water issues, and the practices and policies currently being developed and implemented to mitigate these impacts.

Model for the Part Manufacturing and Vehicle Assembly Component of the Vehicle Life Cycle Inventory

A model is presented for calculating the environmental burdens of the part manufacturing and vehicle assembly (VMA) stage of the vehicle life cycle. The model is based on a process‐level approach, accounting for all significant materials by their transformation processes (aluminum castings, polyethylene blow molding; etc.) and plant operation activities (painting; heating, ventilation, and air conditioning [HVAC], etc.) germane to VMA. Using quantitative results for these material/transformation process pairings, a percent‐by‐weight material/transformation distribution (MTD) function was developed that permits the model to be applied to a range of vehicles, both conventional and advanced (e.g., hybrid electric, light weight, aluminum intensive). Upon consolidation of all inputs, the model reduces to two terms: one proportional to vehicle mass and a plant overhead per vehicle term. When the model is applied to a materially well‐characterized conventional vehicle, reliable estimates of cumulative energy consumption (34 gigajoules/vehicle) and carbon dioxide (CO) emissions (2 tonnes/vehicle) with coefficients of variation are computed for the VMA life cycle stage. Due to the more comprehensive coverage of manufacturing operations, our energy estimates are on the higher end of previously published values. Nonetheless, they are still somewhat underestimated due to a lack of data on overhead operations in part manufacturing facilities and transportation of parts and materials between suppliers and vehicle manufacturing operations. For advanced vehicles, the material/transformation process distribution developed above needs some adjusting for different materials and components. Overall, energy use and CO emissions from the VMA stage are about 3.5% to 4.5% of total life cycle values for vehicles.

Assessment of Expanding Natural Gas Use in Transportation

This report summarizes an analysis of the impacts of a successful expansion of natural gas use by the transportation sector. While natural gas has been successfully introduced into a few niche markets, it currently makes up a small fraction of transportation energy use. The barriers to expansion include several technical issues currently limiting the natural gas vehicle market. If research and development is successful in addressing these technical challenges, there could be a significant shift to natural gas vehicles. With the increased production of cheap natural gas, the Energy Information Administration within the U.S. Department of Energy projects a surplus production of 5.56 trillion cubic feet of natural gas to be exported in 2050. The analysis presented in this report shows that up to 3.40 trillion cubic feet of this surplus could be used by a set of selected transportation modes. The report reviews the current status of the natural gas vehicle market. This includes examining vehicle and engine availability for light-duty, medium-duty, and heavy-duty vehicles. Current and past fuel prices are presented and the price advantage of natural gas is highlighted. The current natural gas refueling infrastructure is reviewed and various options being researched to expand and improve the natural gas infrastructure are presented. The current fossil and renewable natural gas production estimates are summarized and natural gas production projections by the Energy Information Administration are shown. The detailed projections of natural gas use by various consuming sectors through the year 2050 are depicted to show the projected surplus allocated for export. Various barriers to expanded use of natural gas by the transportation sector are reviewed and research and development efforts to overcome these barriers are described. The barriers include the current lower energy efficiency of natural gas engines, cost of on-board natural gas storage, refueling infrastructure costs, potential for natural gas leakage during various handling stages, and renewable natural gas cost and supply. Various modes and sub-sectors within the transportation sector are summarized with their current and projected energy use. A set of modes and sub-sectors is selected as a candidate for expanded natural gas use. Each mode/sub-sector within this set is assigned an introduction year and a maximum market share after evaluating competition from other technologies and natural gas-related limitations. Market penetration profiles are developed for each of these modes/subsectors and sales data are simulated through Argonne’s models. The results in terms of energy use, greenhouse gas emissions, and criteria pollutant emissions are estimated. The change resulting from expanded natural gas use in transportation is summarized in terms of energy consumption by fuel type, greenhouse gas emissions, and NOx emissions.