Assessment of Fuel-Cycle Energy Use and Greenhouse Gas Emissions for Fischer−Tropsch Diesel from Coal and Cellulosic Biomass

The middle distillate fuel produced from natural gas (NG) via the Fischer-Tropsch (FT) process has been proposed as a motor fuel for compression-ignition (CI) engine vehicles. FT diesel could help reduce U.S. dependence on imported oil. The U.S. Department of Energy (DOE) is evaluating the designation of FT diesel as an alternative motor fuel under the 1992 Energy Policy Act (EPACT). As part of this evaluation, DOE has asked the Center for Transportation Research at Argonne National Laboratory to conduct an assessment of well-to-wheels (WTW) energy use and greenhouse gas (GHG) emissions of FT diesel compared with conventional motor fuels (i.e., petroleum diesel). For this assessment, we applied Argonne's Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model to conduct WTW analysis of FT diesel and petroleum diesel. This report documents Argonne's assessment. The results are presented in Section 2. Appendix A describes the methodologies and assumptions used in the assessment.

The pyrolysis of biomass can help produce liquid transportation fuels with properties similar to those of petroleum gasoline and diesel fuel. Argonne National Laboratory conducted a life-cycle (i.e., well-to-wheels [WTW]) analysis of various pyrolysis pathways by expanding and employing the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model. The WTW energy use and greenhouse gas (GHG) emissions from the pyrolysis pathways were compared with those from the baseline petroleum gasoline and diesel pathways. Various pyrolysis pathway scenarios with a wide variety of possible hydrogen sources, liquid fuel yields, and co-product application and treatment methods were considered. At one extreme, when hydrogen is produced from natural gas and when bio-char is used for process energy needs, the pyrolysis-based liquid fuel yield is high (32% of the dry mass of biomass input). The reductions in WTW fossil energy use and GHG emissions relative to those that occur when baseline petroleum fuels are used, however, is modest, at 50% and 51%, respectively, on a per unit of fuel energy basis. At the other extreme, when hydrogen is produced internally via reforming of pyrolysis oil and when bio-char is sequestered in soil applications, the pyrolysis-based liquid fuel yield is low (15% of the dry mass of biomass input), but the reductions in WTW fossil energy use and GHG emissions are large, at 79% and 96%, respectively, relative to those that occur when baseline petroleum fuels are used. The petroleum energy use in all scenarios was restricted to biomass collection and transportation activities, which resulted in a reduction in WTW petroleum energy use of 92-95% relative to that found when baseline petroleum fuels are used. Internal hydrogen production (i.e., via reforming of pyrolysis oil) significantly reduces fossil fuel use and GHG emissions because the hydrogen from fuel gas or pyrolysis oil (renewable sources) displaces that from fossil fuel natural gas and the amount of fossil natural gas used for hydrogen production is reduced; however, internal hydrogen production also reduces the potential petroleum energy savings (per unit of biomass input basis) because the fuel yield declines dramatically. Typically, a process that has a greater liquid fuel yield results in larger petroleum savings per unit of biomass input but a smaller reduction in life-cycle GHG emissions. Sequestration of the large amount of bio-char co-product (e.g., in soil applications) provides a significant carbon dioxide credit, while electricity generation from bio-char combustion provides a large energy credit. The WTW energy and GHG emissions benefits observed when a pyrolysis oil refinery was integrated with a pyrolysis reactor were small when compared with those that occur when pyrolysis oil is distributed to a distant refinery, since the activities associated with transporting the oil between the pyrolysis reactors and refineries have a smaller energy and emissions footprint than do other activities in the pyrolysis pathway.

Oil consumption and import of China increase very quickly in recent years. Because of vehicle population growing in a tremendous speed, nearly 40% of oil has already used in transportation sector in today's China. Many kinds of alternative fuel vehicles are introduced, demonstrated and used in cities to reduce the traditional gasoline and diesel not only to reduce the regulated emissions, but also to improve the oil security of China. When the Kyoto Protocol became effective in last year, Chinese government and experts began to focus on greenhouse gas (GHG) emissions of alternative vehicle fuels. In order to comprehensively evaluating energy and global warming impact lead by production and utilization of alternative vehicle fuels in China, Well-to-Wheel analysis is used in this paper to quantitatively calculate energy use and GHG emissions of recovery, production, transportation and distribution, and end-use of compressed natural gas (CNG), liquefied petroleum gas (LPG), ethanol, methanol, dimethyl ether (DME) and Fischer-Tropsch diesel (FTD). The feedstock of ethanol includes corn and wheat. The energy use and GHG emissions of alternative vehicle fuels are compared with traditional gasoline and diesel. The results show that CNG and LPG is good choice from energy saving and GHG reduction in China. NG-based and coal-based methanol, DME and F-T diesel have lower lifecycle petroleum consumption than traditional gasoline and diesel, so that they may be an answer to Chinese oil security. The lifecycle total energy use, fossil energy use and GHG emissions of NG-based synthesized fuels are lower than coal-based fuels, but obviously higher than traditional gasoline and diesel, so that utilization of them will lead to potential pressure to China GHG reduction responsibility. The GHG emissions performance of China ethanol fuel is not as good as U.S. ethanol. The main reason is abuse of agriculture chemical in corn farming, especial the nitrogenous fertilizer, which is caused great N20 emission

The Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model, developed at Argonne National Laboratory, has been expanded to include well-to-wake (WTWa) analysis of aviation fuels and aircraft. This report documents the key WTWa stages and assumptions for fuels that represent alternatives to petroleum jet fuel. The aviation module in GREET consists of three spreadsheets that present detailed characterizations of well-to-pump and pump-to-wake parameters and WTWa results. By using the expanded GREET version (GREET1{_}2011), we estimate WTWa results for energy use (total, fossil, and petroleum energy) and greenhouse gas (GHG) emissions (carbon dioxide, methane, and nitrous oxide) for (1) each unit of energy (lower heating value) consumed by the aircraft or (2) each unit of distance traveled/ payload carried by the aircraft. The fuel pathways considered in this analysis include petroleum-based jet fuel from conventional and unconventional sources (i.e., oil sands); Fisher-Tropsch (FT) jet fuel from natural gas, coal, and biomass; bio-jet fuel from fast pyrolysis of cellulosic biomass; and bio-jet fuel from vegetable and algal oils, which falls under the American Society for Testing and Materials category of hydroprocessed esters and fatty acids. For aircraft operation, we considered six passenger aircraft classes and four freight aircraft classes in this analysis. Our analysis revealed that, depending on the feedstock source, the fuel conversion technology, and the allocation or displacement credit methodology applied to co-products, alternative bio-jet fuel pathways have the potential to reduce life-cycle GHG emissions by 55-85 percent compared with conventional (petroleum-based) jet fuel. Although producing FT jet fuel from fossil feedstock sources - such as natural gas and coal - could greatly reduce dependence on crude oil, production from such sources (especially coal) produces greater WTWa GHG emissions compared with petroleum jet fuel production unless carbon management practices, such as carbon capture and storage, are used.

The Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model, developed at Argonne National Laboratory, has been expanded to include well-to-wake (WTWa) analysis of aviation fuels and aircraft. This report documents the key WTWa stages and assumptions for fuels that represent alternatives to petroleum jet fuel. The aviation module in GREET consists of three spreadsheets that present detailed characterizations of well-to-pump and pump-to-wake parameters and WTWa results. By using the expanded GREET version (GREET1_2011), we estimate WTWa results for energy use (total, fossil, and petroleum energy) and greenhouse gas (GHG) emissions (carbon dioxide, methane, and nitrous oxide) for (1) each unit of energy (lower heating value) consumed by the aircraft or(2) each unit of distance traveled/ payload carried by the aircraft. The fuel pathways considered in this analysis include petroleum-based jet fuel from conventional and unconventional sources (i.e., oil sands); Fisher-Tropsch (FT) jet fuel from natural gas, coal, and biomass; bio-jet fuel from fast pyrolysis of cellulosic biomass; and bio-jet fuel from vegetable and algal oils, which falls under the American Society for Testing and Materials category of hydroprocessed esters and fatty acids. For aircraft operation, we considered six passenger aircraft classes and four freight aircraft classes in this analysis. Our analysis revealed that, depending on the feedstock source, the fuel conversion technology, and the allocation or displacement credit methodology applied to co-products, alternative bio-jet fuel pathways have the potential to reduce life-cycle GHG emissions by 55–85 percent compared with conventional (petroleum-based) jet fuel. Although producing FT jet fuel from fossil feedstock sources — such as natural gas and coal — could greatly reduce dependence on crude oil, production from such sources (especially coal) produces greater WTWa GHG emissions compared with petroleum jet fuel production unless carbon management practices, such as carbon capture and storage, are used.

In 2009, manure management accounted for 2,356 Gg or 107 billion standard cubic ft of methane (CH{sub 4}) emissions in the United States, equivalent to 0.5% of U.S. natural gas (NG) consumption. Owing to the high global warming potential of methane, capturing and utilizing this methane source could reduce greenhouse gas (GHG) emissions. The extent of that reduction depends on several factors - most notably, how much of this manure-based methane can be captured, how much GHG is produced in the course of converting it to vehicular fuel, and how much GHG was produced by the fossil fuel it might displace. A life-cycle analysis was conducted to quantify these factors and, in so doing, assess the impact of converting methane from animal manure into renewable NG (RNG) and utilizing the gas in vehicles. Several manure-based RNG pathways were characterized in the GREET (Greenhouse gases, Regulated Emissions, and Energy use in Transportation) model, and their fuel-cycle energy use and GHG emissions were compared to petroleum-based pathways as well as to conventional fossil NG pathways. Results show that despite increased total energy use, both fossil fuel use and GHG emissions decline for most RNG pathways as compared with fossil NG and petroleum. However, GHG emissions for RNG pathways are highly dependent on the specifics of the reference case, as well as on the process energy emissions and methane conversion factors assumed for the RNG pathways. The most critical factors are the share of flared controllable CH{sub 4} and the quantity of CH{sub 4} lost during NG extraction in the reference case, the magnitude of N{sub 2}O lost in the anaerobic digestion (AD) process and in AD residue, and the amount of carbon sequestered in AD residue. In many cases, data for these parameters are limited and uncertain. Therefore, more research is needed to gain a better understanding of the range and magnitude of environmental benefits from converting animal manure to RNG via AD.

Life Cycle Assessment of fossil energy use and greenhouse gas emissions in Chinese pear production

A fuel cycle model—called the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) model—has been developed to evaluate well-to-wheels (WTW) energy and emission impacts of motor vehicle technologies fueled with various transportation fuels. The GREET model contains various hydrogen (H2) production pathways for fuel cell vehicle (FCV) applications. In this study, the GREET model was expanded to include four nuclear H2 production pathways: (a) H2 production at refueling stations via electrolysis using light water reactor–generated electricity, (b) H2 production in central plants via thermochemical water cracking using heat from a high-temperature gas-cooled reactor (HTGR), (c) H2 production in central plants via high-temperature electrolysis using HTGR-generated electricity and steam, and (d) H2 production at refueling stations via electrolysis using HTGR-generated electricity. The WTW analyses of these four options include these stages: uranium ore mining and milling, uranium yellowcake transportation, uranium conversion, uranium enrichment, uranium fuel fabrication, uranium fuel transportation, electricity or H2 production in nuclear power plants, H2 transportation, H2 compression, and H2 FCV operation. Our well-to-pump results show that significant reductions in fossil energy use and greenhouse gas (GHG) emissions are achieved by nuclear-based H2 compared to natural gas–based H2 production via steam methane reforming for a unit of H2 delivered at refueling stations. When H2 is applied to FCVs, the WTW results also show large benefits in reducing fossil energy use and GHG emissions.

Cropping system diversification can reduce the negative environmental impacts of agricultural production, including soil erosion and nutrient discharge. Less is known about how diversification affects energy use, climate change, and air quality, when considering farm operations and supply chain activities. We conducted a life cycle study using measurements from a nine-year Iowa field experiment to estimate fossil energy (FE) use, greenhouse gas (GHG) emissions, PM2.5-related emissions, human health impacts, and other agronomic and economic metrics of contrasting crop rotation systems and herbicide regimes. Rotation systems consisted of 2-year corn-soybean, 3-year corn-soybean-oat/clover, and 4-year corn-soybean-oat/alfalfa-alfalfa systems. Each was managed with conventional and low-herbicide treatments. FE consumption was 56% and 64% lower in the 3-year and 4-year rotations than in the 2-year rotation, and GHG emissions were 54% and 64% lower. Diversification reduced combined monetized damages from GHG and PM2.5-related emissions by 42% and 57%. Herbicide treatment had no significant impact on environmental outcomes, while corn and soybean yields and whole-rotation economic returns improved significantly under diversification. Results suggest that diversification via shifting from conventional corn-soybean rotations to longer rotations with small grain and forage crops substantially reduced FE use, GHG emissions, and air quality damages, without compromising economic or agronomic performance.

This study performed technoeconomic and life-cycle analyses to assess the economic feasibility and emission benefits and tradeoffs of various biofuel production pathways as an alternative to conventional marine fuels. We analyzed production pathways for (1) Fischer-Tropsch diesel from biomass and cofeeding biomass with natural gas or coal, (2) renewable diesel via hydroprocessed esters and fatty acids from yellow grease and cofeeding yellow grease with heavy oil, and (3) bio-oil via fast pyrolysis of low-ash woody feedstock. We also developed a new version of the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET) marine fuel module for the estimation of life-cycle greenhouse gas (GHG) and criteria air pollutant (CAP) emissions of conventional and biobased marine fuels. The alternative fuels considered have a minimum fuel selling price between 2.36 and 4.58 $/heavy fuel oil gallon equivalent (HFOGE), and all exhibit improved life-cycle GHG emissions compared to heavy fuel oil (HFO), with reductions ranging from 40 to 93%. The alternative fuels also exhibit reductions in sulfur oxides and particulate matter emissions. Additionally, when compared with marine gas oil and liquified natural gas, they perform favorably across most emission categories except for cases where carbon and sulfur emissions are increased by the cofed fossil feedstocks. The pyrolysis bio-oil offers the most promising marginal CO2 abatement cost at less than $100/tonne CO2e for HFO prices >$1.09/HFOGE followed by Fischer-Tropsch diesel from biomass and natural gas pathways, which fall below $100/tonne CO2e for HFO prices >$2.25/HFOGE. Pathways that cofeed fossil feedstocks with biomass do not perform as well for marginal CO2 abatement cost, particularly at low HFO prices. This study indicates that biofuels could be a cost-effective means of reducing GHG, sulfur oxide, and particulate matter emissions from the maritime shipping industry and that cofeeding biomass with natural gas could be a practical approach to smooth a transition to biofuels by reducing alternative fuel costs while still lowering GHG emissions, although marginal CO2 abatement costs are less favorable for the fossil cofeed pathways.

Low-carbon production of iron and steel: Technology options, economic assessment, and policy

Wastewater treatment plants (WWTPs) produce sludge as a byproduct when they treat wastewater. In the United States, over 8 million dry tons of sludge are produced annually just from publicly owned WWTPs. Sludge is commonly treated in anaerobic digesters, which generate biogas; the biogas is then largely flared to reduce emissions of methane, a potent greenhouse gas. Because sludge is quite homogeneous and has a high energy content, it is a good potential feedstock for other conversion processes that make biofuels, bioproducts, and power. For example, biogas from anaerobic digesters can be used to generate renewable natural gas (RNG), which can be further processed to produce compressed natural gas (CNG) and liquefied natural gas (LNG). Sludge can be directly converted into hydrocarbon liquid fuels via thermochemical processes such as hydrothermal liquefaction (HTL). Currently, the environmental impacts of converting sludge into energy are largely unknown, and only a few studies have focused on the environmental impacts of RNG produced from existing anaerobic digesters. As biofuels from sludge generate high interest, however, existing anaerobic digesters could be upgraded to technology with more economic potential and more environmental benefits. The environmental impacts of using a different anaerobic digestion (AD) technology to convert sludge into energy have yet to be analyzed. In addition, no studies are available about the direct conversion of sludge into liquid fuels. In order to estimate the energy consumption and greenhouse gas (GHG) emissions impacts of these alternative pathways (sludge-to-RNG and sludge-to-liquid), this study performed a lifecycle analysis (LCA) using the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET®) model. The energy uses and GHG emissions associated with the RNG and hydrocarbon liquid are analyzed relative to the current typical sludge management case, which consists of a single-stage mesophilic digester with biogas flaring. Along with the alternative HTL process, four types of AD technologies with fuel production—single-stage mesophilic, mesophilic 2-stage, single-stage mesophilic with thermohydrolysis treatment, and mesophilicmesophilic acid/gas phase—are studied. Results show that the sludge-to-CNG pathway via AD and the sludge-to-liquid pathway via HTL reduce GHG emissions consumptions significantly. When we compare the GHG emissions of the alternative fuel production pathways to that of the counterfactual case in terms of the amount of sludge treated, reductions in GHG emissions are 39%–80% and 87% for alternative AD and HTL, respectively. Compared to petroleum gasoline and diesel GHG emission results in terms of MJ, the renewable CNG production pathway via AD and the renewable diesel production pathway via HTL reduce GHG emissions by 193% and 46%, respectively. These large reductions are mainly due to GHG credits from avoiding GHGs under the counterfactual scenario, and/or fertilizer displacement credits. Similarly, reductions in fossil fuel use for sludge-based fuels are huge. However, well-defined counterfactual scenarios are needed because the results of the study depend on the counterfactual scenario, which might vary over time.

Life-cycle energy use and greenhouse gas emissions of palm fatty acid distillate derived renewable diesel

A model for fossil energy use in Danish agriculture used to compare organic and conventional farming

GHG Emissions and Fossil Energy Use as Consequences of Efforts of Improving Human Well-being in Africa