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Lifecycle analysis

[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.]

Fraunhofer, KIT study finds CO2 mitigation potential of higher-range PHEVs greater than expected

November 29, 2017

In an open-access paper published in Scientific Reports, a team from Fraunhofer ISI and KIT (Karlsruhe Institute of Technology) has presented the first systematic overview of empirical findings on the electrification of vehicle mileage based on on actual PHEV (plug-in hybrid) and BEV (battery-electric vehicle) usage for the US and Germany. The team found that, contrary to common belief, a PHEV with about 60  km (37 miles) of real-world range currently electrifies as many annual vehicles kilometers as a BEV, despite having a much smaller battery.

Further, they found that when the higher CO2eq emissions generated during the production phase of BEVs compared to PHEVs (due to the much larger BEV battery) are included in the analysis, a PHEV today shows higher CO2eq savings then BEVs compared to conventional vehicles. For significant ongoing CO2eq improvements of PHEVs—and particularly of BEVs—the decarbonization of the electricity system needs to continue, the researchers said.

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UMTRI study shows wide global variability in GHG emissions from operating an EV

November 07, 2017

A team at the University of Michigan Transportation Research Institute (UMTRI) study has assessed the relative amounts of greenhouse-gas emissions from driving a battery-electric vehicle (BEV) compared with greenhouse-gas emissions from driving a traditional gasoline-powered vehicle in different countries of the world.

Indirect emissions from BEVs depend on the mix of fuel sources used to generate electricity; countries differ widely in their fuel-source mix. For example, Albania (which generates 100% of its electricity from hydroelectric power) would have an average 5,100.0 MPGghg (0.05 L/100 km) for a BEV; on the other extreme are Botswana and Gibraltar (which generate 100% of their electricity from coal and oil), each with 29.0 MPGghg (8.1 L/100 km). The corresponding value for the US is 55.4 MPGghg (4.2 L/100 km)—interestingly, close to the 54.5 mpge target for the US EPA’s current GHG regulations for 2025. The average for the world is 51.5 MPGghg (4.6 L/100 km).

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Study: expanding Brazilian sugarcane for ethanol could reduce global CO2 emissions by up to 5.6%

October 24, 2017

Vastly expanding sugarcane production in Brazil for conversion to ethanol could reduce current global CO2 emissions by as much as 5.6%, according to a new study by an international team led by researchers from the University of Illinois.

This would be a massive undertaking, involving the conversion of hundreds of thousands of square miles—at its most ambitious, more than the combined land area of Texas and California—to sugarcane fields. However, it could be accomplished without impinging on environmentally sensitive areas in Brazil and while allowing for the expansion of other agricultural crops and human needs, the researchers report in a paper in the journal Nature Climate Change. The carbon-related costs of converting the land to sugarcane fields were included in the analysis.

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Study finds air pollution and GHG costs of crude-by-rail nearly 2x pipeline costs; much larger than spill and accidents costs

October 11, 2017

Researchers from Carnegie Mellon University and the University of Pittsburgh have found that the air pollution and greenhouse gas costs of shipping crude by rail are nearly twice as large as those for oil pipelines. Further, their estimates of air pollution and greenhouse gas costs are much larger than estimates of spill and accidents costs—more than twice as big for rail and more than eight times as big for pipelines.

The findings of their study, published by the National Bureau of Economic research, suggest that the policy debate surrounding crude oil transportation has put too much relative weight on accidents and spills, while overlooking a far more serious source of external cost: air pollution and greenhouse gas emissions.

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Argonne updates GREET and AFLEET tools for transportation technologies analysis

Researchers at Argonne National Laboratory have released updates to two key tools for the analysis of advanced transportation technologies: GREET, used to assess greenhouse gases, regulated emissions and energy use in transportation; and AFLEET, used to calculate and compare the costs and environmental benefits of a broad range of alternative fuel technologies.

GREET. The first version of GREET was released in 1996. Since then, Argonne has continued to update and expand the model. The most recent GREET versions are the GREET1 2017 version for fuel-cycle analysis and GREET2 2017 version for vehicle-cycle analysis. The 2017 release of the suite of GREET (Greenhouse gases, Regulated Emissions, and Energy use in Transportation) models and associated documentation includes the following expansions and updates:

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T&E concludes that diesel cars emit more CO2 on a full lifecycle basis than gasoline cars

September 18, 2017

A new analysis by the NGO Transport & Environment (T&E) concludes that diesel cars emit more CO2 than equivalent cars on a full lifecycle basis—i.e., accounting for the emissions generated during production of the vehicle and the fuel.

According to the T&E analysis, an average diesel car produces emits 3.65 tonnes more CO2 than an equivalent gasoline car over its lifetime due to a more energy-intensive refining of the diesel fuel; more materials required in the production of heavier and more complex engines; higher emissions from biodiesel blended in the diesel fuel; and longer mileage because fuel is cheaper.

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Digging into the differences in carbon accounting for biofuels

August 24, 2017

The benefit to the climate of using biofuels as a substitute for fossil fuels has been sharply contested for years; much of the disagreement is based on the assumptions underlying the carbon accounting in the lifecycle analysis. The argument essentially boils down to whether or not biofuels are inherently carbon neutral because the CO2 released when they are burned is derived from CO2 uptake during feedstock growth.

A paper and subsequent formal comments and responses in the journal Climatic Change highlights the conceptual differences and the impact on policy. Professor John DeCicco at the University of Michigan Energy Institute has grown increasingly critical of the lifecycle analysis methods used to justify and administer biofuel policies. In a 2016 open-access paper in Climatic Change, he and his colleagues argued that once estimates for process emissions and displacement effects including land-use change are considered, US biofuel use to date is associated with a net increase rather than a net decrease in CO2 emissions. (earlier post)

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Stanford study finds energy requirements of super-giant oilfields can significantly increase over time

July 17, 2017

A new study finds that as some of the world’s largest oilfields age, the energy required to keep them operating can rise dramatically even as the amount of petroleum they produce drops. Failing to take the changing energy requirements of oilfields into account can cause oilfield managers or policymakers to underestimate the true climate impacts, Stanford scientists warn.

Mohammad Masnadi and Adam Brandt used decades-long time-series data from twenty-five globally significant oil fields (>1 billion barrels ultimate recovery) to model greenhouse gas (GHG) emissions from oil production as a function of time.Depletion requires increased energy expenditures in drilling, oil recovery, and oil processing. They found that volumetric oil production declines with depletion, but that this depletion is accompanied by significant growth—in some cases more than tenfold—in per-MJ GHG emissions.

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GLBRC research review concludes cellulosic biofuels can benefit the environment if managed correctly

June 30, 2017

Cellulosic biofuels could provide an environmentally sustainable way of meeting energy needs—but with a few important caveats, according to a new review of research by a team from the US Department of Energy-funded Great Lakes Bioenergy Research Center (GLBRC). Their paper is published in the journal Science.

Although not yet a market force, cellulosic biofuels are routinely factored into future climate mitigation scenarios because of their potential to both displace petroleum use and mitigate greenhouse gas emissions. Those benefits, however, are complicated by the need for vast amounts of land to produce cellulosic biofuels on a large scale.

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Study projects emission impacts of inexpensive, efficient EVs: 36% further reduction in LDV GHG by 2050, or 9% economy-wide

June 07, 2017

A new study by researchers at the University of Colorado at Boulder projects the emission impacts of the widespread introduction of inexpensive and efficient electric vehicles into the US light duty vehicle (LDV) sector. The work is reported in a paper in the ACS journal Environmental Science & Technology.

Under their optimistic scenario (OPT)—which is based on the assumption that EVs are market-competitive with gasoline vehicles, in particular after 2025—they find 15% and 47% adoption of battery electric vehicles (BEVs) in 2030 and 2050, respectively. Compared to the reference case, in which gasoline vehicles (ICEVs) remain dominant through 2050 (BAU), OPT results in 16% and 36% reductions in LDV greenhouse gas (GHG) emissions for 2030 and 2050, respectively, corresponding to 5% and 9% reductions in economy-wide emissions.

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GM earns EPA ENERGY STAR Award for Environmental Leadership; energy use per vehicle in manufacturing down 10% YoY

April 12, 2017

General Motors earned a 2017 EPA ENERGY STAR Partner of the Year — Sustained Excellence award for continued leadership in protecting the environment through superior energy efficiency. GM’s commitment to reducing energy intensity saved $73 million in energy costs last year and avoided 388,000 metric tons of carbon emissions, equivalent to the electricity use of 57,000 US homes.

In the US, GM reduced energy use at its manufacturing facilities by 10% on a per-vehicle basis in 2016 compared to the previous year. Additional achievements include:

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ICCT: alternative jet fuels unlikely to deliver the bulk of GHG emission reductions needed by aviation

April 10, 2017

A new study by a team at the International Council on Clean Transportation (ICCT) has concluded that the large-scale deployment of alternative jet fuels (AJFs) and the ability of the aviation sector to mitigate greenhouse gas (GHG) emissions through their use will be capped by a number of factors: the sustainability and availability of feedstock; the production cost; and the extent to which those fuels will be commercialized.

Based on the study, the ICCT team suggests that while the use of AJFs can deliver some GHG savings, it is unlikely that AJF alone can meet the bulk of the GHG reductions projected to be needed. The authors recommended that ICAO stipulate a GHG reduction threshold in order for a given AJF to qualify under CORSIA (Carbon Offsetting and Reduction Scheme for International Aviation), and to include indirect emissions in its life-cycle accounting.

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TÜV lifecycle analysis shows Mercedes-Benz E 350 e PHEV cuts GHG footprint 44% compared to E 350 CGI; equivalent NOx

February 15, 2017

The Mercedes-Benz E 350 e plug-in hybrid (earlier post) has successfully completed the TÜV validation audit and received the Environmental Certificate. This award is based on a Life Cycle Assessment (LCA) in which the independent experts at TÜV Süd (the German Technical Inspection Authority) comprehensively assess the environmental impact of the passenger car over its entire life cycle.

The Mercedes-Benz E 350 e is rated with an NEDC fuel consumption of 2.1 l/100 km (112 mpg US), and electric energy consumption (NEDC) of 11.5 kWh/100 km. The LCA found total CO2 emissions around 44% lower than the previous E 350 CGI model, which has comparable performance data and a conventional engine, during its life cycle (material manufacture, production, driving for 250,000 kilometers (155,000 miles) calculated with certified consumption figures and recycling) when the hybrid model is charged externally with the European energy mix.

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USDA: US corn-based ethanol reduces GHG emissions by 43% compared to gasoline, with additional benefits projected through 2022

January 13, 2017

A new lifecycle analysis of corn ethanol released by the US Department of Agriculture (USDA) finds that GHG emissions associated with corn-based ethanol in the United States are about 43% lower than gasoline when measured on an energy-equivalent basis. Unlike other studies of GHG benefits, which relied on forecasts of future ethanol production systems and expected impacts on the farm sector, this study reviewed how the industry and farm sectors performed over the past decade to assess the current GHG profile of corn-based ethanol.

The new report, A Life-Cycle Analysis of the Greenhouse Gas Emissions of Corn-Based Ethanol, found greater lifecycle GHG benefits from corn ethanol than a number of earlier studies, driven by a variety of improvements in ethanol production, from the corn field to the ethanol refinery. Farmers are producing corn more efficiently and using conservation practices that reduce GHG emissions, including reduced tillage, cover crops and improved nitrogen management. Corn yields are also improving—between 2005 and 2015, US corn yields increased by more than 10%.

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WVU study fully characterizes pump-to-wheels methane emissions from HD natural gas vehicles and fueling stations

January 12, 2017

Researchers at West Virginia University have characterized pump-to-wheels methane emissions from heavy-duty (HD) natural-gas-fueled vehicles and the compressed natural gas (CNG) and liquefied natural gas (LNG) fueling stations that serve them. The study, published as an open-access paper in the ACS journal Environmental Science & Technology, greatly expands on very limited data on methane emissions from natural gas-fueled vehicles.

The WVU pump-to-wheels study is the first end-use paper in a collaborative scientific research series designed to measure and better understand the sources and amount of greenhouse-gas methane that is emitted across the natural gas supply chain.

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