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Researchers propose evaluating alt fuel efficiency based on energy rather than volume; impact of ethanol on vehicle efficiency and GHGs
May 17, 2013
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| Relative changes in vehicle energy efficiency (VEE) (km/MJ) on ethanol/gasoline blends over those on gasoline for different blending levels. Credit: ACS, Yan et al. Click to enlarge. |
In a policy analysis in the ACS journal Environmental Science & Technology, researchers from the Universities of Cambridge, Exeter and Oxford argue that, due to the increased emphasis on alternative fuels with drastically differing energy densities, vehicle efficiency should be evaluated based on energy rather than volume.
With that as a premise, they go on to show that the efficiency of existing vehicles can be both positively and negatively affected by ethanol content, ranging from −15% to +24%. As a result, they conclude, uncertainties in the net greenhouse gas (GHG) effect of ethanol, particularly when used in a low-level blend with gasoline, are considerably larger than previously estimated. Standard deviations increase by >10% and >200% when used in high and low blends, respectively.
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Study finds large-scale ramp-up in biofuel crops could result in warming in some tropical regions, cooling in temperate and polar regions
May 08, 2013
Global land-use changes caused by a major ramp-up in biofuel crops—enough to meet about 10% of the world’s energy needs—could make some regions warmer, according to a new integrated modeling study by researchers from MIT and the Marine Biological Laboratory, Woods Hole.
Using an integrated assessment model that links an economic model with climate, terrestrial biogeochemistry, and biogeophysics models, the team examined the biogeochemical and biogeophysical effects of possible land use changes from an expanded global second-generation bioenergy program on surface temperatures over the first half of the 21st century.
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NTNU study finds ships’ and spare parts’ contribution to offshore wind power lifecycle impacts has been underestimated
March 04, 2013
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| Reference scenario impact indicator values by eight components and nine stressor sources. Components: WT = wind turbine; Fnd = foundation; EC = electrical connections, including substation; Inst = installation; IOo = input-output, other; Mnt = Maintenance, excluding replacement parts; RP = replacement parts; EOL = end-of-life. Credit: ACS, Arvesen et al. Click to enlarge. |
A new analysis by researchers at the Norwegian University of Science and Technology (NTNU) suggests that, notwithstanding significant uncertainties, previous studies have underestimated the contributions from installation and use phases—e.g., “ships and spare parts”—to the total life cycle impacts of offshore wind power. Their analysis is published in the ACS journal Environmental Science & Technology.
In the study, they developed and assessed life cycle inventories of a the proposed Havsul I offshore wind farm in Norway using a hybrid life cycle assessment (LCA) methodology. The study put special emphasis on aspects of installation, operation, and maintenance, as these stages have been given only cursory consideration in previous LCAs, they noted.
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State Department issues Draft Supplemental Environmental Impact Statement on Keystone XL Pipeline: climate change impacts
March 02, 2013
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| Comparison of proposed Keystone XL route to previously proposed project segment. Source: Draft SEIS. Click to enlarge. |
The US Department of State (DOS) has released its Draft Supplemental Environmental Impact Statement (SEIS) in response to TransCanada’s May 2012 application for the Keystone XL pipeline that would run from Canada’s oils sands in Alberta to Nebraska. The document is a detailed draft technical review of potential environmental impacts associated with the segment of the pipeline in the US, including: impacts from construction, impacts from potential spills, impacts related to climate change, and economic impacts.
Aside from the potential construction and spill impacts of the pipeline, the scope of the climate change impacts have become the most contentious and politicized issue surrounding the pipeline. The DOS SEIS accordingly takes a detailed look at life-cycle greenhouse gas emissions of petroleum products from Western Canadian Sedimentary Basin (WCSB) oil sands crudes compared with reference crudes and the potential impact the pipeline might have on climate change as well as on the future development of the oils sands resource in Canada.
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DeCicco: Transportation GHG reduction policy should focus upstream on fuel supply rather than downstream on choice of fuels in vehicles
January 25, 2013
In a new working paper, Prof. John DeCicco at the University of Michigan argues that to reduce transportation sector greenhouse gas emissions, the proper policy focus should be upstream in sectors that provide the fuel, rather than downstream on the choice of fuels in the automobile.
More specifically, he suggests that other than supporting fundamental R&D, programs to promote alternative fuel vehicles (AFVs) “are not currently warranted for climate protection. In addition to managing travel demand and improving vehicle efficiency, the implied climate policy priority is limiting net GHG emissions in fuel supply sectors.” The paper is available from the Social Science Research Network (SSRN).
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New Argonne lifecycle analysis of bioethanol pathways finds corn ethanol can reduce GHG emissions relative to gasoline by 19-48%; long-term, cellulosic offers the most benefits
January 22, 2013
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| Well-to-wheels results for greenhouse gas emissions in CO2e for six pathways. Source: Wang et al. Click to enlarge. |
A new lifecycle analysis of five bioethanol production pathways by a team from Argonne National Laboratory led by Dr. Michael Wang found that, relative to petroleum gasoline, ethanol from corn; sugarcane; corn stover; switchgrass; and miscanthus can reduce lifecycle greenhouse gas (GHG) emissions [P10-P90 (P50)] by 19–48% (34%); 40–62% (51%); 90–103% (96%); 77–97% (88%); and 101–115% (108%), respectively when including land use change emissions. They researchers reported similar trends with regard to fossil energy benefits for the five bioethanol pathways. An open access paper on the study in published in the journal Environmental Research Letters.
While the results for cellulosic ethanol (stover, switchgrass and miscanthus) are in line with recent studies, and the findings for sugarcane ethanol are only slightly lower than other similar studies, the results for corn ethanol are in sharp contrast to other studies predicting that corn ethanol would have a greater life-cycle GHG impact than gasoline, the authors noted.
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Tsinghua University provincial-level lifecycle study finds fuel-cycle criteria pollutants of EVs in China could be up to 5x those of natural gas vehicles due to China’s coal-dominant power mix
January 12, 2013
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| Consumption-based power mixes and NG transmission distances by Chinese province in 2010. Credit: ACS, Huo et al. Click to enlarge. |
A province-by-province life cycle analysis of natural gas and electric vehicles by a team from Tsinghua University concludes that while, from the perspective of reducing greenhouse gas (GHG) and criteria pollutant emissions, natural gas vehicles (CNGVs) are “an option with no obvious merits or demerits”, electric vehicles (EVs) are “an option with significant merits and demerits in this regard” due to China’s heavily coal-based electricity generation (national average of about 77%).
In regions where the share of coal-based electricity is relatively low, EVs can achieve substantial GHG reduction, the team reports in a paper in the ACS journal Environmental Science & Technology. However, the fuel-cycle PM10, PM2.5, SO2, and NOx emissions of EVs could be up to five times higher than those of ICEVs (internal combustion engine vehicles) and CNGVs. While the increases in PM10 and PM2.5 emissions are less important because of the low contribution of light duty vehicles to national PM10 and PM2.5 emissions, the NOx and SO2 increases are significant enough to notably change total national emissions, they conclude.
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Spatially explicit life cycle assessment of 5 sun-to-wheels pathways finds photovoltaic electricity and BEVs offer land-efficient and low-carbon transportation
January 04, 2013
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| Direct land use, life cycle GHG emissions (excluding indirect land use change), and life cycle fossil fuel requirements to generate the transportation services provided by 17.8 × 1012 MJ NCV of gasoline, the amount used in transportation in the US in 2009. Credit: ACS, Geyer et al. Click to enlarge. |
A new spatially-explicit life cycle assessment of five different “sun-to-wheels” conversion pathways—ethanol from corn or switchgrass for internal combustion vehicles (ICVs); electricity from corn or switchgrass for battery-electric vehicles (BEVs); and photovoltaic electricity for BEVs—found a strong case for PV BEVs.
According to the findings by the team from the University of California, Santa Barbara and the Norwegian University of Science and Technology, published in the ACS journal Environmental Science & Technology, even the most land-use efficient biomass-based pathway (i.e., switchgrass bioelectricity in US counties with hypothetical crop yields of more than 24 tonnes/ha) requires 29 times more land than the PV-based alternative in the same locations.
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Cornell team quantifies uncertainty in life cycle assessments of algae biofuel production; suggests reporting results as ranges of expected values
January 01, 2013
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| (a) Energy Return on Energy Invested (EROI) values from previously published LCA studies of algal biofuel production. (b) EROI values resulting from the “worst” and “best” cases of this study. Center lines represent median values, edges of boxes represent 25th and 75th percentiles, and error bars represent 5th and 95th percentiles of the distributions resulting from 10,000 Monte Carlo simulations. Credit: ACS, Sills et al. Click to enlarge. |
A Cornell University team has used a Monte Carlo approach to quantify the role of uncertainty associated with process parameters in life cycle analysis (LCA) of algae-to-biofuel schemes for determining metrics such as Energy Return on (Energy) Invested (EROI) and global warming potential global warming potential (GWP). The results, reported in a paper in the ACS journal Environmental Science & Technology, show that uncertainties exist at all stages of biofuel production from microalgae, from cultivation to dewatering to conversion processes and production of coproducts.
This indicates, the researchers suggest, that the values reported in earlier studies are not incorrect, but, rather each represent a specific case. These cases should not be used solely to conclude whether algal biofuels are expected to be energetically viable or environmentally sustainable, the authors say. Instead, LCA results, especially those associated with developing technologies such as algal biofuel, should be reported as ranges of expected values to provide decision makers with reliable results, they conclude.
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New petroleum refining lifecycle model finds the variability in GHG emissions from refining different crudes as significant as magnitude expected in upstream operations
December 09, 2012
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| Comparison of GHGenius, JACOBS, TIAX, and the new PRELIM gasoline greenhouse gas (GHG) estimates using base case estimates and variations from the scenario analysis. Credit: ACS, Abella and Bergerson. Click to enlarge. |
Researchers at the University of Calgary (Canada) have developed the Petroleum Refinery Life-cycle Inventory Model (PRELIM). PRELIM uses a more comprehensive range of crude oil quality and refinery configurations than used in earlier models and can quantify energy use and greenhouse gas (GHG) emissions with detail and transparency the better to inform policy analysis, the duo suggests.
Using a scenario analysis to explore the implications of processing crudes of different qualities in different refinery configurations, and with a focus on oil sands products, they found differences of up to 14 g CO2eq/MJ of crude, or up to 11 g CO2eq/MJ of gasoline and 19 g CO2eq/MJ of diesel (the margin of deviation in the emissions estimates is roughly 10%). Put another way, “the variability in GHG emissions in the refining stage that results from processing crudes of different qualities is as significant as the magnitude expected in upstream operations”, they found.
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Report from Victoria EV Trial reinforces importance of source of electricity and EV efficiency in reducing greenhouse gas emissions
December 07, 2012
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| Interrelationship between EV energy economy (y-axis) and and the electricity grid emissions intensity (x-axis) in determining full fuel cycle greenhouse gas emissions. The color regions represent 100 gCO2e/ km increments in full fuel cycle emissions performance. A conventional Mazda 3 would sit around midway of the middle color band at 154 gCO2e/km. Source: “Environmental Impacts”. Click to enlarge. |
The Victoria (Australia) EV Trial—a major 5-year initiative (earlier post)—has released a comparative lifecycle assessment of the environmental impacts of electric vehicles relative to conventional gasoline vehicles in Victoria from now until 2030.
The lifecycle analysis, “Environmental Impacts of Electric Vehicles in Victoria”, found that the impacts from vehicle operation far outweigh those from vehicle production—true even if allowing for an EV battery replacement over the vehicle life. Vehicle disposal impacts, including those of the EV battery, were found to be negligible due to the expected high rate of material recycling. The dominant influence of vehicle operation during the EV lifecycle thus highlights the importance of the source of electricity, how efficient the energy conversion in the vehicle is, and the way a vehicle is used, the report found.
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IHS CERA meta-analysis finds lifecycle GHG emissions for fuel produced solely from oil sands crude average 11% higher than from average crude refined in the US; high variability
November 15, 2012
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| Average values for WTW GHG emissions for oil sands and other crudes, tight boundary. Source: IHS CERA. Click to enlarge. |
When the boundary for measuring GHG emissions is placed around crude production and processing facilities, for fuels produced solely from Canadian oil sands the average well-to-wheels (WTW) life-cycle GHG emissions are 11% higher than for the average crude refined in the United States (results range from 4% to 18% higher), according to a new meta-analysis by energy market consultancy IHS CERA.
When the oil sands products refined in the United States are considered—a mixture of oil sands and lower-carbon blending components—the GHG emissions are, on average, 9% higher than the average crude processed in the US.
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Researchers describe the “where” and “when” of life cycle emissions from gasoline and ethanol in the US
October 11, 2012
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| Contributions of regions to total life cycle emissions for three fuels (µg per vehicle-mile traveled per km2 land area). Dashed lines show US average emissions. Credit: ACS, Tessum et al. Click to enlarge. |
Researchers from the University of Minnesota have produced a spatially and temporally explicit life cycle inventory (LCI) of air pollutants from gasoline, ethanol derived from corn grain, and ethanol from corn stover for the contiguous US (the lower 48 states). A paper on their work is published in the ACS journal Environmental Science & Technology.
Life cycle inventories have typically been presented at global, national, or regional levels—sufficient for understanding global processes such as climate change and fossil fuel depletion, but insufficient for the analysis of local processes such as air pollution, according to the researchers. The spatially (12 km grids) and temporally explicit LCI not only provides the level of detail necessary to perform detailed LCIA (life cycle impact assessment) of air pollutant emissions, it also gives information on spatial and temporal trends that can be useful in policy making and regulation, the authors suggest.
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New full LCA highlights complexity of environmental advantages and disadvantages of EVs relative to ICE vehicles; the importance of life cycle thinking
October 07, 2012
Researchers at the Norwegian University of Science and Technology (NTNU) have compared the emissions resulting from the production, use, and end-of-life of electric and internal combustion engine vehicles (EVs and ICEVs) in a full life-cycle analysis (LCA). They found that electric vehicles (EVs) powered by the present European electricity mix offer a 10% to 24% decrease in global warming potential (GWP) relative to conventional diesel or gasoline vehicles assuming lifetimes of 150,000 km (93,206 miles).
However, they also found that EVs exhibit the potential for significant increases in human toxicity, freshwater eco-toxicity, freshwater eutrophication, and metal depletion impacts, largely resulting from the vehicle supply chain. Their results, they cautioned in an open-access paper published in the Journal of Industrial Ecology, are sensitive to assumptions regarding electricity source, use-phase energy consumption, vehicle lifetime, and battery replacement schedules.
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LCA study finds Alcoa forged aluminum wheels cut carbon footprint of commercial vehicles
October 01, 2012
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| Alcoa aluminum truck wheels vs. steel wheels (average use case). Source: Alcoa. Click to enlarge. |
Alcoa last week released the findings of a peer-reviewed life cycle assessment (LCA) which concluded that Alcoa aluminum wheels substantially cut the carbon footprint of commercial vehicles.
This analysis, performed by PE International and Five Winds Strategic Consulting, is the most comprehensive and transparent comparative LCA ever conducted on aluminum and steel truck wheels, according to Alcoa. It analyzed the entire “cradle-to-grave” production process of commercial vehicle wheels—from bauxite mining to wheel manufacturing, through a truck wheel’s use phase and end-of-life, including recycling and land filling. The study incorporated the latest available information on energy and material consumption, greenhouse gas emissions and other environmental releases.
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Brazilian biofuels with LUC may have much higher non-GHG emissions than conventional gasoline and diesel
September 24, 2012
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| Comparisons of life-cycle emissions from LUC phase for (a) sugar cane ethanol and (b) soybean biodiesel. Credit: ACS, Tsao et al. Click to enlarge. |
When including Land Use Change (LUC) factors, Brazilian sugar cane ethanol and soybean biodiesel have much larger life-cycle emissions than conventional gasoline and biodiesel for six regulated, non-greenhouse gas (GHG) air pollutants, according to a study led by a team from the University of California, Merced. The pollutants are NMHC, CO, NOx, TPM, PM2.5 and SOx.
Even with the application of the “Green Ethanol Protocol”—which will eliminate sugar cane pre-harvest burning in the future—Brazilian biofuels including sugar cane ethanol and soybean biodiesel are still likely to have higher air pollution impacts than conventional fossil fuels due to the LUC effects if the LUC occurs as projected through 2020, according to the researchers. A paper on their work is published in the ACS journal Environmental Science & Technology.
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ICCT study finds European biofuel mandates without consideration of iLUC have a substantial probability of increasing net GHG emissions
September 18, 2012
A new study by Dr. Chris Malins of the International Council on Clean Transportation (ICCT) finds that without including indirect Land Use Change (iLUC) factors (or some other effective iLUC minimization approach), European biofuel mandates are unlikely to deliver significant greenhouse gas (GHG) emissions benefits in 2020, and have a substantial probability of increasing net GHG emissions.
In contrast, he found, the implementation of iLUC factors is likely to significantly increase the carbon savings from EU biofuel policy. With iLUC factors, it is likely that most permitted pathways would conform to the Renewable Energy Directive requirement for a minimum 50% GHG reduction compared to fossil fuels.
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German researches conclude EU rapeseed biodiesel extremely unlikely to meet current definition of sustainability
August 20, 2012
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| GHG emissions savings of rapeseed FAME compared to RED “typical” and “default” levels. Dashed line indicates RED threshold of 35%. Pehnelt and Vietze. Click to enlarge. |
In a new analysis of GHG emissions savings potential of rapeseed biodiesel produced in the EU, a pair of researchers from GlobEcon, an independent economics and politics research and consulting institute based in Jena, Germany, conclude that the GHG emissions saving values of rapeseed biodiesel stated by the EU “are more than questionable.”
“Given these striking differences as well as the lack of transparency in the EU’s calculations,” they write, “we assume that the EU seems to prefer ‘politically’ achieved typical and default values regarding rapeseed biodiesel over scientifically proven ones.” The findings are published as a Jena Economic Research Paper, a joint publication of the Friedrich Schiller University and the Max Planck Institute of Economics, Jena, Germany.
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Oil sands GHG lifecycle study using operating data finds lower emitting oil sands cases outperform higher emitting conventional crude cases; a call for more sophisticated tools and reporting
July 07, 2012
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| Well-to-wheel (WTW) greenhouse gas emissions for in situ SAGD and surface mining pathways generated employing GHOST/TIAX/ GHGenius combination and comparison with SAGD, mining and conventional crude oil literature pathways (all results are on a HHV basis). Xs show comparative results from literature. Credit: ACS, Bergerson et al. Click to enlarge. |
A new well-to-wheel (WTW) lifecycle analysis (LCA) by a team from the University of Calgary and the University of Toronto of greenhouse gas (GHG) emissions from transportation fuels produced from Canadian oil sands finds that, on a WTW basis, lower emitting oil sands cases can outperform higher emitting conventional crude cases.
The LCA, reported in the ACS journal Environmental Science & Technology, is the first based on confidential operating data from oil sands projects, the authors said. The wide range of potential emissions intensities for both oil sands and conventional crudes suggests that treating all oil sands or all conventional crudes as having the same emissions may lead to unintended consequences, according to the team. In addition, they note, the emissions associated with all of the petroleum sources will continue to change over time (e.g., a transition to heavier conventional oil, technology improvements, deteriorating reservoir conditions as the oil sands resource is further developed).
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California ARB posts LCFS pathway for biomethane from dry fermentation; -15.29 g CO2e/MJ, compared to +95.86 and +94.71 for gasoline and diesel
July 05, 2012
The California Air Resources Board (ARB) has posted a new Low Carbon Fuel Standard (LCFS) internal pathway for biomethane produced from the high solids anaerobic digestion (HSAD) (dry fermentation) of organic (food and green) wastes—with accommodations for small proportions of food-contaminated, non-recyclable (soiled) paper, and fats, oils, and greases (FOG) in the feedstock. The HSAD fuel carbon intensity is -15.29 g CO2e/MJ, compared to gasoline and diesel carbon intensities of 95.86 and 94.71g CO2e/MJ respectively.
The pathway, developed in partnership with CalRecycle, is based on a multi-stage, mesophilic process to produce biomethane for use as a vehicle fuel. The feedstock for this pathway is 40% food waste and 60% green waste. The carbon intensity analysis takes into account well-to-wheel emissions including avoided landfill and composting emissions and compost co-product credits for the displacement of synthetically produced fertilizer.
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Honda to begin reuse of rare earth metals extracted from used NiMH batteries before year end; targeting extraction from motors and Li-ion batteries as well
June 20, 2012
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| Flow of the reuse of rare earth metals Honda is striving to achieve. Click to enlarge. |
Honda Motor Co., Ltd., which has been extracting rare earth metals from used nickel-metal hydride batteries at the plant of Japan Metals & Chemicals Co., Ltd. from April of this year, plans to begin reusing the extracted metals before the end of 2012.
Honda will pursue the recycling of precious resources by reusing extracted rare earth metals not only for nickel-metal hydride batteries, but also for use in a wide range of parts. Further, in disassembly process of used nickel-metal hydride batteries, Honda is considering efforts to recover any residual voltage from the used nickel-metal hydride batteries and use it as regenerative voltage for the disassembly process.
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Univ of Toronto study details impacts of interaction between driving patterns and electricity generation for WTW energy use and GHG emissions for PHEVs
May 23, 2012
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| WTW GHG emissions of vehicles across driving patterns and PHEV charging scenarios. Solid portions represent GHG emissions associated with gasoline propulsion. Patterned portions represent GHG emissions associated with electric propulsion. (Solid left bar = hydro electricity scenario.) Credit: ACS, Raykin et al. Click to enlarge. |
A new study by researchers at the University of Toronto examines the impact of the interaction between driving patterns (distance and conditions) and the mode of electricity generation (e.g., coal, hydro, natural gas) on well-to-wheel (WTW) energy use and greenhouse gas (GHG) emissions of plug-in hybrid electric vehicles (PHEVs). Their paper is published is the ACS journal Environmental Science & Technology.
Driving patterns affect the WTW performance of PHEVs in two ways, they found. First, driving distance determines the proportions of electricity and gasoline consumed by the PHEV. Second, driving conditions impact the fuel efficiency of all vehicle technologies, but there are differences in the impact across technologies. Fuel efficiency, in turn, affects the magnitude of energy use and GHG emissions associated with each WTW stage.
