[Due to the increasing size of the archives, each topic page now contains only the prior 365 days of content. Access to older stories is now solely through the Monthly Archive pages or the site search function.]
CMU study compares lifecycle GHGs of natural gas pathways for MHDVs; MD BEVs can deliver large reductions, but diesel hard to beat for Class 8
May 27, 2015
A study by Carnegie Mellon University researchers comparing life cycle greenhouse gas (GHG) emissions from different natural gas pathways for medium and heavy-duty vehicles (MHDVs) found that the GHG reduction potentials of the pathways vary sharply between non-Class 8 MHDVs (e.g., pick-up trucks, parcel delivery trucks, and box trucks), Class 8 transit buses, and Class 8 MHDVs (e.g., refuse trucks and tractor-trailers).
Battery-electric (BEVs), LPG, and CNG pathways could reduce life cycle GHG emissions for non-Class 8 MHDVs compared to the baseline petroleum fuels. Similarly, BEVs achieve emission reductions for transit buses. On the other hand, none of natural gas pathways, CNG, LNG, and F-T liquids, achieve any emission reductions per unit of freight-distance moved for Class 8 trucks compared to conventional diesel. The study is published in the ACS journal Environmental Science & Technology.
Lifecycle study finds fuel switching from diesel to natural gas could produce net climate damage absent reductions in CH4 emissions and improved vehicle efficiency
May 20, 2015
A study by a team from the Environmental Defense Fund, in collaboration with a colleague from the Lenfest Center for Sustainable Energy at Columbia University has found that while switching a heavy-duty truck fleet from diesel to natural gas has the potential to produce climate benefits, realizing that potential would require a combination of significant reductions well-to-wheels methane emissions (i.e., addressing leakage) and efficiency improvements in the natural gas vehicles themselves. Otherwise, fuel switching can produce net climate damages (more radiative forcing) for decades.
The results, published in an open access paper in the ACS journal Environmental Science & Technology, suggest that policymakers wishing to address climate change should use caution before promoting fuel switching to natural gas, the authors concluded.
U Toronto LCA suggests that with CNG as primary vehicle energy source, EVs best targeted at non-attainment areas
April 01, 2015
A team at the University of Toronto has examined the life cycle air emissions (climate change and human health) impact benefits and life cycle ownership costs of compressed natural gas (CNG) use directly in conventional vehicles (CV) and hybrid electric vehicles (HEV), and natural gas-derived electricity (NG-e) use in plug-in battery electric vehicles (BEV), using a gasoline-fueled conventional vehicle as a reference.
Among their findings, published in a paper in the ACS journal Environmental Science & Technology, are that policies should for the foreseeable future focus on the niche adoption of plug-in vehicles in non-attainment regions, as CNG vehicles are likely more cost-effective at providing overall life cycle air emissions impact benefits.
Mercedes-Benz C 350 e PHEV can reduce full lifecycle CO2 emissions up to 41% compared to gasoline-engined C 250
March 18, 2015
Compared to the gasoline-engined C 250, the Mercedes-Benz C 350 e plug-in hybrid (earlier post) can reduce full life-cycle (manufacture, use over 200,000 km and recycling) CO2 emissions by some 26% (9.6 tonnes) when charging with the European electricity mix and by up to 41% (15.1 tonnes) when charging with renewable power.
The analysis is outlined in the plug-in’s newly release “Life Cycle” brochure, the results of which have also been confirmed by TÜV Süd, a branch of the German Technical Inspection Agency. The new plug-in hybrid satisfies all criteria of an environmentally responsible product development pursuant to ISO standard TR 14062.
Study: natural gas heavy-duty trucking fleet could benefit economy, but has mixed environmental effects
February 20, 2015
Switching from diesel fuel to natural gas may hold advantages for the US heavy-duty trucking fleet, but more needs to be done to reach the full environmental benefits, according to a new white paper released by the Institute of Transportation Studies at the University of California, Davis, and Rice University.
The recent shale-driven emergence of natural gas as an abundant, inexpensive fuel in the US has raised the possibility of a “momentous shift” in the level of natural gas used in transportation. The cost advantage of natural gas over diesel fuel is particularly appealing for vehicles with a high intensity of travel and thus fuel use. In the paper, the team investigated the possibility that natural gas could be utilized to provide fuel cost savings, geographic supply diversity and environmental benefits for the heavy-duty trucking sector—and whether it can enable a transition to lower carbon transport fuels.
New LCFS pathway applications show Abengoa cellulosic ethanol with CI of 29.52 and 23.36 g CO2e/MJ
February 06, 2015
California Air Resources Board (ARB) staff has posted thirteen new Low Carbon Fuel Standard (LCFS) fuel pathway applications to the LCFS public comments website. Among them are two pathways for cellulosic ethanol produced by Abengoa Bioenergy at its Hugoton, Kansas plant. One pathway uses corn stover for feedstock, the other uses wheat straw. The carbon intensity (CI) for corn stover cellulosic ethanol is estimated to be 29.52 g CO2e/MJ; for wheat straw ethanol, the CI is estimated to be 23.36 g CO2e/MJ. The 2015 LCFS compliance schedule target for gasoline and fuels used as a substitue for gasoline is 96.48 g CO2e/MJ.
Corn stover comprises the dried leaves, stalks, husk, and cobs left on the ground after the harvest of the corn crop. Wheat straw is the dried stalk of the wheat crop after the grain and chaff have been removed. The carbon intensities of both pathways include the GHG emissions impacts associated with the nutrients that must be applied to fields from which stover and straw have been removed to make up for the nutrients lost when residues are removed.
California ARB issues feedstock-only pathway for camelina-based fuels under LCFS; zero ILUC emissions results in very low CI fuels
February 05, 2015
The California Air Resources Board has issued Sustainable Oils Inc., a wholly owned subsidiary of Global Clean Energy Holdings, a feedstock-only pathway for the production of camelina-based fuels under the Low Carbon Fuel Standard (LCFS). The feedstock-only CI (carbon intensity) is 7.58 gCO2e/MJ.
A feedstock-only pathway allows a fuel producer interested in producing either biodiesel or renewable diesel from a camelina feedstock using Sustainable Oils’ proprietary seed varieties to combine the CI of this pathway for the production of a camelina oil feedstock with the carbon intensity components of the fuel producer’s specific fuel production and transportation processes. The feedstock-only pathway includes only the CI components for farming, agricultural chemicals, camelina transportation, and oil extraction.
Study finds wide range in GHG intensities and production costs of cellulosic ethanol from corn stover, switchgrass and miscanthus
February 04, 2015
A team led by researchers from the University of Illinois at Urbana-Champaign has developed an integrated framework to determine and to compare greenhouse gas (GHG) intensities and production costs of cellulosic ethanol derived from corn stover, switchgrass, and miscanthus grown on high and low quality soils for three representative counties in the Eastern United States.
In their study, published in the ACS journal Environmental Science & Technology they found that—compared to gasoline—the GHG savings from miscanthus-based ethanol ranged between 130% and 156% whereas that from switchgrass ranged between 97% and 135%. The corresponding range for GHG savings with corn stover was 57% to 95% and marginally below the threshold of at least 60% for biofuels classified as cellulosic biofuels under the Renewable Fuels Standard.
Thai researchers find waste chicken fat a good low-cost feedstock for renewable diesel
January 19, 2015
In a study investigating the effect of the water and free fatty acid (FFA) content in waste chicken fat from poultry processing plants on the production of renewable diesel (not biodiesel), researchers in Thailand have found that both higher FFA and water content improved the biohydrogenated diesel (BHD) yield.
In their paper, published in the ACS journal Energy & Fuels, they reported that the presence of water accelerated the breakdown of the triglyceride molecules into FFAs, while the presence of more FFAs also increased yield. Therefore, they concluded, waste chicken fat from food industries containing a high degree of FFAs and water content can be used as a low-cost feedstock for renewable diesel production without requiring a pretreatment process.
New version of Argonne lifecycle model for water footprint of biofuels now includes cellulosic feedstocks
January 16, 2015
Argonne National Laboratory released the newest version (3.0) of the online tool Water Assessment for Transportation Energy Resources (WATER) this week. This latest version of WATER allows, for the first time, biofuels manufacturers to analyze water consumption associated with use of cellulosic feedstocks such as residue left from lumber production and other wood-based resources. The new tool also provides analysis down to the county level in the US for the first time.
WATER adopts a water footprint methodology, and contains extensive climate, land use, water resource, and process water data. Version 3.0 of WATER thus can help biofuels developers gain a detailed understanding of water consumption of various types of feedstocks, aiding development of sustainable fuels that will reduce impact on limited water resources.
ASG life-cycle study finds aluminum Ford F-150 “Best Full-size Truck of 2015” from environmental and economic perspective
January 14, 2015
According to the latest annual life-cycle study from the Automotive Science Group (ASG), the all-new lightweight aluminum 2015 Ford F-150 leads the full-size light-duty truck competition in all environmental and economic performance areas; accordingly, ASG selected the F-150 as its Best Full-size Truck of 2015. According to ASG and the principles of ecological economics, environmental and economic considerations are equally important in determining a vehicle’s overall value. ASG’s proprietary vehicle rating platform—the Automotive Performance Index—analyzes both performance areas for a comprehensive vehicle assessment. ASG’s 2015 Study assessed 225 light-duty truck models.
Although the gasoline-fueled F-150 with 2.7L EcoBoost delivers 22 mpg (10.68 l/100 km) combined—1 mpg shy of RAM’s EcoDiesel—the F-150’s life-cycle environmental and economic performance “leaves RAM and others in the dust,” according to ASG. According to ASG, the 2015 F-150 holds the smallest life-cycle carbon footprint and lowest cost of ownership of any full-size truck in the North American market today. Ford has produced a lightweight aluminum-intensive truck that costs less and performs better than its conventional truck counterparts over the vehicle’s life-cycle, says Colby Self, managing director of ASG.
Mercedes-Benz B-Class Electric Drive reduces lifecycle CO2 emissions by as much as 64% compared to B 180 gasoline model
December 17, 2014
|CO2 emissions of the B-Class Electric Drive compared with the B 180 gasoline-engine variant [t/car]. Click to enlarge.|
The Mercedes-Benz B-Class Electric Drive (earlier post) delivers up to 64% lower CO2 emissions than the equivalent B 180 gasoline model (when charged with hydroelectricity), according to Mercedes-Benz and TÜV Süd. The 132 kW B Class Electric Drive has a range of some 200 km (124 miles). TÜV Süd has awarded the electric-drive Sports Tourer the environmental certificate in accordance with ISO standard TR 14062 based on a comprehensive life-cycle assessment of the B-Class Electric Drive.
Over its entire life cycle, comprising production, use over 160,000 kilometers (99,419 miles) and recycling, the B-Class Electric Drive produces emissions of CO2 that are 24% (7.2 tonnes – EU electricity mix) or 64% (19 tonnes – hydroelectricity) lower than those of the B 180, despite the higher emissions generated during the production process.
Lifecycle analysis of Amyris renewable jet from sugar cane finds “substantial potential” to mitigate GHG emissions, but a wide range of potential outcomes
November 25, 2014
|Monte Carlo results for the net life cycle emissions of the renewable jet fuel from sugar cane. Credit: ACS, Moreira et al.. Click to enlarge.|
Brazilian researchers evaluating the lifecycle GHG emissions of a renewable jet fuel produced from sugar cane in Brazil using Amyris’ proprietary technology platform (earlier post) found that the farnesane-based renewable fuel presents “a substantial potential” to mitigate the GHG emissions of the aviation sector. Their paper is published in the ACS journal Environmental Science & Technology.
In their base case, the researchers calculated a “rather optimistic” GHG footprint of 8.5g CO2eq/MJ; lifecycle emissions of fossil jet fuel usually lie within the 80−95g CO2eq/MJ range. However, they noted, the estimation is highly uncertain, with a number of factors—especially related to electricity exports, sugar cane farming itself, and agrochemicals production and use—significantly affect the outcome. The results of the Monte Carlo analysis indicate life cycle emissions of 21 ± 11 g CO2eq/MJ (mean ± SD), with substantial influence from the LUC factor.
Ecofys report concludes current European regulations underestimating GHG reductions
November 13, 2014
Substituting biofuels for marginal fossil-based liquid fuels results in the avoidance of significant GHG emissions that are not currently accounted for in the European Renewable Energy Directive (2009/28/EC), according to a new analysis by the consultancy Ecofys. The study was commissioned by the European Oilseed Alliance (EOA), the European Biodiesel Board (EBB) and the European Vegetable Oil and Proteinmeal Industry (FEDIOL).
The European RED and the Fuel Quality Directive (2009/30/EC) both assess the GHG benefits of biofuels by comparing the lifecycle emissions of biofuels to a “fossil comparator”. However, the Ecofys authors note, the current comparator does not reflect the increasing emissions of fossil fuels that are becoming more difficult to extract. In addition, they argue, biofuels should not just be compared to the average performance of gasoline or diesel but with the fossil fuels they most likely replace—i.e. those that are marginally “not produced”.
Study casting doubt on GHG benefits of corn stover ethanol draws sharp criticism by other researchers; Liska responds
October 30, 2014
A study published earlier this year in the journal Nature Climate Change that cast doubt on whether biofuels produced from corn residue could meet federal mandates for cellulosic biofuels to reduce greenhouse gas emissions by 60% compared to gasoline (earlier post) has drawn critical response published as correspondence in the same journal.
The study led by University of Nebraska-Lincoln assistant professor Adam Liska, funded through a three-year, $500,000-grant from the US Department of Energy, used carbon dioxide measurements taken from 2001 to 2010 to validate a soil carbon model that was built using data from 36 field studies across North America. Among their findings were that using corn crop residue to make ethanol and other biofuels reduces soil carbon and under some conditions can generate more greenhouse gases than gasoline.
Argonne releases GREET 2014 lifecycle analysis software; unified graphical toolbox and database
October 08, 2014
The GREET (The Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation Model) team at Argonne National Laboratory has released a new version of the widely used GREET lifecycle analysis tool, GREET 2014. GREET 2014 provides a fully graphical toolbox with which users can perform life cycle analysis simulations of alternative transportation fuels and vehicle technologies with just a few clicks.
GREET originally began development as an Excel spreadsheet back in 1996. As the detail and complexity of the tool has grown, the spreadsheet-based approach became unwieldy, the team said. As a result, the GREET team is now using the new software (called GREET.NET to differentiate from GREET Excel) as a new platform for life cycle assessment studies and database management. The new platform combines all the previous Excel spreadsheets in a single environment with a single database that is now easier to maintain and manage.
ORNL study finds best current use of natural gas for cars is efficient production of electricity for EVs
September 24, 2014
|Top: Components of well-to-wheels pathway. Middle: WTW efficiency for CNGVs. Bottom: WTW efficiency for EVs. Curran et al. Click to enlarge.|
A well-to-wheels analysis of the use of natural gas for passenger vehicles by a team of researchers from Oak Ridge National Laboratory (ORNL) has found that, with a high PTW (pump-to-wheels) efficiency and the potential for high electrical generation efficiency with NGCC (natural gas combined cycle) turbines, natural gas currently is best used in an efficient stationary power application for charging EVs.
However, they also noted, high PTW efficiencies and the moderate fuel economies of current compressed natural gas vehicles (CNGVs) make them a viable option as well. If CNG were to be eventually used in hybrids, the advantage of the electric generation/EV option shrinks. Their open access paper is published in the journal Energy.
US MARAD study finds marine use of natural gas substantially reduces some air pollutants and slightly reduces GHG emissions
August 26, 2014
A recently released total fuel cycle analysis for maritime case studies shows that natural gas fuels reduce some air quality pollutants substantially, and reduce major greenhouse gas (GHG) emissions slightly, when compared to conventional petroleum-based marine fuels (low-sulfur and high-sulfur). The study was released by the US Department of Transportation’s (DOT) Maritime Administration (MARAD) and was conducted through a cooperative partnership with the Maritime Administration, the University of Delaware and The Rochester Institute of Technology.
They also found that the upstream configuration for natural gas supply matters in terms of minimizing GHG emissions on a total fuel cycle basis, and that the current infrastructure for marine fuels may produce fewer GHGs. Continued improvements to minimize downstream emissions of methane during vessel-engine operations will also contribute to lower GHG emissions from marine applications of natural gas fuels.
U. Mich study: natural-gas-based ICE, BEV and FCV all show promise for environmental benefits relative to conventional ICE
August 19, 2014
Results of a lifecycle analysis by a team at the University of Michigan suggest that multiple types of natural gas-powered vehicles—i.e., natural-gas burning ICE vehicles; battery-electric vehicles (BEVs) recharged with gas-generated electricity; and fuel cell vehicles (FCVs) using hydrogen produced from natural gas—all show promise for reducing environmental impacts, energy demand and climate change impacts relative to conventional petroleum-fueled internal combustion engined vehicles for personal mobility.
Qiang Dai and Christian Lastoskie found that BEVs and FCVs in particular offer significant reductions in greenhouse gas emissions, especially if carbon capture and sequestration (CCS) technologies are implemented at the fuel conversion facilities. Their study appears in the ACS journal Energy & Fuels.
3rd generation Audi TT reduces full lifecycle GHGs by 11% compared to predecessor
August 18, 2014
|Lifecycle greenhouse gas emissions for 2nd and 3rd generation TTs. Click to enlarge.|
Audi’s new third-generation TT reduces life-cycle greenhouse gas emissions by 11% compared to its predecessor. This results in a reduction of around 5.5 tonnes of GHGs—CO2, methane, nitrous oxide and halogenated organic emissions—over its entire lifecycle. At the same time, Audi has increased the power output in the new TT by up to 14%.
A number of technologies have contributed towards the positive life cycle assessment of the Audi TT, including lightweight construction. Using an intelligent combination of materials, Audi engineers have, for the second time in a row, succeeded in reducing the car’s unladen weight.
U Mich professor finds fuel cycle analysis for evaluating CO2 impacts of liquid fuels is fatally flawed; calls for focus on CO2 removal
July 28, 2014
Fuel cycle analysis (FCA)—or “well-to-wheels analysis”—is a type of lifecycle analysis (LCA) that examines fuel products and their supply chains, and that has greatly influenced climate-related research priorities and public policies for transportation fuels.
However, in a major review of methods for evaluating the net CO2 impacts of liquid transportation fuels, Professor John DeCicco at the University of Michigan Energy Institute (UMEI) compared FCA to other methods of analysis, and found “flaws fatal enough to raise serious concerns about the role of FCA in shaping fuel-related CO2 mitigation strategies. Instead, DeCicco proposes “setting the lifecycle paradigm aside” and focusing on the problem of carbon dioxide removal.
Researchers propose CO2 recycling to improve Fischer-Tropsch GTL efficiency and reduce total CO2 emissions
June 21, 2014
|Overview of the CUGP processes. Credit: ACS, Zhang et al. Click to enlarge.|
Researchers in South Korea are suggesting two new carbon-dioxide-utilized Gas-to-Liquids processes (CUGP) to increase the overall efficiency of conventional Fischer-Tropsch GTL. In a paper in the ACS journal Environmental Science & Technology, they report that the two CUGP options increase carbon efficiency by 21.1−41.3% and thermal efficiency by 15.7−40.7%, with total CO2 emissions reduced by 82.0−88.4%, compared to different conventional F-T processes.
This results in a decrease in total CO2 emissions to less than 5g CO2/MJ F-T product, compared to a range of 27.0 to 36.2g CO2/MJ F-T product for the conventional processes.
MIT study finds significant economic and environmental benefits from designing US LDVs to use higher octane gasoline (98 RON)
May 29, 2014
In a companion study to an SAE paper presented in April (earlier post), researchers at MIT have quantified the net economic and CO2 emissions benefit that could be obtained by utilizing 98 RON gasoline in light-duty vehicles, based on reasonable assumptions for possible refinery changes and the evolution of the LDV fleet. The paper, they note, is the first modern, peer-reviewed publication to address the costs and benefits of introducing higher octane gasoline.
According to the analysis, published in the ACS journal Environmental Science & Technology, greater use of 98 RON gasoline in appropriately tuned vehicles could further reduce annual gasoline consumption in the US by 3.0–4.4%. Even accounting for the increase in refinery emissions from production of additional high-RON gasoline, net CO2 emissions are reduced by 19–35 Mt/y in 2040 (2.5–4.7% of total direct LDV CO2 emissions). The MIT team estimated the annual direct economic benefit to be $0.4–6.4 billion in 2040, and the annual net societal benefit—including the social cost of carbon—to be $1.7–8.8 billion in 2040.